Patent Application
20230209720
The present disclosure relates to fabrication and assembly of printed circuit boards including deposition of conductive traces and placement of components.
Modern electrical devices are comprised of semiconductor circuits integrated into small packages, passive components, Printed Wiring Board (PWB) and solder. The complete assembly is often referred as a Printed Circuit Board (PCB) or Printed Circuit Assembly (PCA). The manufacture of a traditional PCA is a multistep process that may include several specialized and often expensive machines. These highly specialized machines are directed to one operation during the PCA manufacture. For example, a typical PWB, is manufactured using a thin sheet of copper foil that is laminated to a non-conductive substrate. The copper thickness may be 1.4 mils (1 ounce) and the substrate is typically FR-4 with a substrate thickness of 62 mils. Other thicknesses and substrates are also available.
Referring to
Referring to
When complex circuits are manufactured especially for a small dimensional footprint, the complete board may contain multiple printed wiring boards stacked to allow copper lines to cross over each other while maintaining electrical isolation. Referring to
Highly specialized equipment is used to manufacture printed wiring boards in order to rapidly fabricate the boards at an economical cost. The etching equipment only performs one of several tasks optionally used to assemble a complete PCA. Once the printed wiring board is etched and drilled, the exposed copper traces are typically coated with solder, silver, nickel/gold, or some other anti-corrosion coating. The finished printed wiring board is then typically sent to another facility for assembly of electronic components onto the PWB. The attachment of electronic components, e.g., semiconductor and passive components, are made using a solder reflow process. In one typical process, solder paste is applied to the PWB using screen printing techniques. Once the solder is printed onto the board, the electrical components are positioned onto the board. Positioning the components is often referred as “pick-and-place”. Components may be manually placed, often with tweezers, or in high volume production, components may be placed with a computer controlled machine. Once the components are all positioned on the solder paste, the PCA is placed in an oven to melt (reflow) the solder paste which will permanently attach the components to the board. Because of the multiple machines and technologies involved, this complete process can often take up to 4 weeks to complete.
The process of determining routing of the conductive traces is often performed using a Computer Aided Design (CAD) software tool. When using CAD, an operator enters a schematic of a desired circuit including electrical components and package sizes. The CAD tool generates a set of files used as a mask when chemically etching each layer of the PWB. The same file is optionally used to control a Computer Numerically Controlled (CNC) milling machine when mechanically etching the PWB. When mechanically etching the PWB, the CNC milling machine removes copper along an outside edge of a desired conductive trace leaving behind a copper line that is electrically isolated from other conductive traces. The CAD tool output is in a file format that is typically Gerber. Gerber is an industry standard in the PWB industry which allows multiple vendors to share the same data without loss of information. The file format is optionally native to the CAD tool such as Eagle, OrCAD and Altium to name a few. In all cases, there is information for each layer of the PWB. During the layout process, the CAD tool will attempt to route the conductive traces based on a set of design rules which include the number of layers used in the PWB. For example, an entry in the CAD tool may be the use of a four-layer board which implies that there will be four independent layers of conductive traces. The CAD tool will route conductive traces to cross over each other while not making electrical contact. When the CAD tool knows that insulating layers exist between the multiple conductive layers and knowing that the insulating layers extend to the edges of the PWB, cross-overs are easily created by dropping the line from one layer of conductive traces to a second layer of conductive traces and moving across the layer and finally returning to the original side of the PWB. As an example, referring to
The conventional multilayer PCB production method is expensive and requires multiple machines to produce a multilayer PCB. Thus, a need exist for a single apparatus and method which can produce a completed circuit board and optionally populate the circuit board with components.
Apparatuses and methods for printing circuit boards using conductive and nonconductive materials, such as inks and epoxies, printed using print heads are available. Printing using such devices can result in printed traces being defective. This increase time and cost associated with such printing. Materials used in such printing also degrade with age which increases the possibility of defects occurring. Furthermore, environmental conditions can also affect the quality of printing done. Additionally, available materials may vary over time which also affects the printing quality if methods employed are not varied to compensate for material variations.
Accordingly, it is an object of the disclosure to provide a PCB production apparatus and method which provides for producing PCB's using ink and/or epoxy printing and optionally component placement which can overcome the disadvantages presented by adverse effects of material aging, environmental conditions, and material variations.
Briefly stated an apparatus and method are configured to print a circuit board using conductive and nonconductive printing materials in accordance with parameters. A database stores information correlating characteristics of printing materials with shelf life and/or age of the printing materials, and/or environmental conditions. The apparatus either prompts operator to make printing parameter adjustments or automatically optimizes printing parameters based on information stored in the database and the environmental conditions. The apparatus optionally further optimizes printing parameters based on age of a print head and positioning mechanisms.
A further embodiment of the present disclosure provides an apparatus for producing a printed circuit board on a substrate, has a table for supporting the substrate, a function head configured to effect printing conductive and non-conductive materials on the substrate, a positioner configured to effect movement of the function head relative to the table, and a controller configured to operate the function head and the positioner to effect the printing of conductive and non-conductive materials on the substrate. The apparatus optionally has a layout translation module configured to accept PCB multilayer circuit board files and convert multilayer circuit board layout data of the PCB multilayer circuit board files to printing data files for controlling the function head to print conductive material and nonconductive material onto the substrate to produce a printed circuit effecting functionality of the multilayer circuit board layout data.
In accordance with these and other objects of the disclosure, there is further provided an embodiment of the above described apparatus further having a component feed device disposed to present components for placement on the substrate with the substrate disposed on the table. The function head includes a component placement device configured to pick up the components and release the components. The controller is further configured to operate the component placement device, the function head and the positioner to effect placement the components on the substrate.
In a further embodiment of the present disclosure, an apparatus as described above is provided wherein the layout translation module is configured to accept the PCB multilayer circuit board files and convert component placement data of the PCB multilayer circuit board files to placement data files configured for controlling the function head and the component placement device to accept the components from the component feed device and place the components onto the substrate in accordance with the placement data files.
In yet a further embodiment of the present disclosure, an apparatus according to any of the above described embodiments is provided further comprising at least one heat source disposed to effect heating of the substrate with the substrate disposed on the table.
In another embodiment of the present disclosure there is provided a kit for printing a circuit on a substrate to produce a printed circuit board on a substrate. The kit comprises a conductive material print head containing a conductive material to be printed on the substrate, a nonconductive material print head containing a nonconductive material to be printed on the substrate, and a printing apparatus. The printing apparatus includes a table for supporting the substrate, a function head configured to accept installation, either simultaneously or one at a time, of the conductive material print head, or the nonconductive material printhead, and a positioner configured to effect movement of the function head and the table relative to one another. Further included is a controller configured to accept PWB data to operate the function head and the positioner to effect: printing on the substrate the nonconductive material when the function head has the nonconductive material print head installed; printing on the substrate of the conductive material to form printed conductors when the function head has the conductive material print head installed; and reprinting one or more of the printed conductors in response to test input indicating the one or more printed conductors fail testing.
A feature of the above embodiments includes the controller being configured to prompt an operator for the test input reflecting a status of a printed conductor. Another feature includes the controller operating a display of one or more of the printed conductors which is configured to prompt the operator for the test input corresponding to one or more of the printed conductors. Another optional feature provides for display presenting a diagram of the printed conductors.
Yet another feature of the above embodiments includes an electrical testing device having testing probe for test printed conductors at at least one point. The function head is configured to accept installation, either simultaneously or one at a time, of the conductive material print head, the nonconductive material printhead, or the testing probe. When the testing probe is installed in the function head, the controller operates the positioner and the function head to effect testing of the printed conductors to produce the test input indicating the one or more printed conductors fail testing and effect the reprinting of the one or more printed conductors in response to the test input. In an embodiment the testing probe and the conductive material printhead are simultaneously installed in the function head. In another embodiment the testing probe is integrated into the conductive material print head. A possible configuration includes the conductive material print head being an ink j et print head and the testing probe protruding from a bottom surface of the ink jet print head. In a further arrangement of the present disclosure the testing probe includes two probe contacts and the testing device effects a resistance measurement.
Still another embodiment of the present disclosure provides a kit for printing a circuit on a substrate to produce a printed circuit board on a substrate, wherein the kit comprises a conductive material print head containing a conductive material to be printed on the substrate, a nonconductive material print head containing a nonconductive material to be printed on the substrate, and a printing apparatus. The printing apparatus has a table for supporting the substrate, a function head configured to accept installation, either simultaneously or one at a time, of the conductive material print head, or the nonconductive material printhead. A positioner is configured to effect movement of the function head and the table relative to one another. A controller is configured to accept PWB data to operate the function head and the positioner to effect printing on the substrate the nonconductive material when the function head has the nonconductive material print head installed, printing on the substrate of the conductive material to form printed conductors and conductor pads when the function head has the conductive material print head installed; and generation of alignment structure data, based on the PWB data, which defines nonconductive alignment structures configured to align electrical components with the conductive pads when the components are installed on the conductive pads.
Further features of the above embodiment provide the nonconductive alignment structures including a nonconductive wall configured to surround the electrical components, or the nonconductive alignment structures including a nonconductive bosses configured to align the electrical components with the conductive pads. Aspects of this feature further provide that the nonconductive bosses are L-shaped, or crescent shaped, or round dots.
Still further aspects of the above embodiments of the present disclosure provide a controller is configured to accept data identifying areas of the substrate requiring stiffening and generate stiffening structure data for directing printing of the nonconductive material to form a stiffening support, and to operate the function head and the positioner to effect printing on the substrate the nonconductive material to form the stiffening structure when the function head has the nonconductive material print head installed.
Yet another embodiment of the present disclosure provides a kit for printing a circuit on a substrate to produce a printed circuit board on a substrate, with the kit comprising a conductive material print head containing a conductive material to be printed on the substrate, a nonconductive material print head containing a nonconductive material to be printed on the substrate, and a printing apparatus. The printing apparatus comprises a table for supporting the substrate, a function head configured to accept installation, either simultaneously or one at a time, of the conductive material print head, or the nonconductive material printhead, a positioner configured to effect movement of the function head and the table relative to one another, and a controller. The controller is configured to accept PWB data to operate the function head and the positioner to effect printing on the substrate the nonconductive material when the function head has the nonconductive material print head installed, and printing on the substrate of the conductive material to form printed conductors and conductor pads when the function head has the conductive material print head installed. The controller is further configured to accept data identifying areas of the substrate requiring stiffening and generate stiffening structure data for directing printing of the nonconductive material to form a stiffening support, and to operate the function head and the positioner to effect printing on the substrate the nonconductive material to form the stiffening structure when the function head has the nonconductive material print head installed.
In a further embodiment of the present disclosure there is provided a kit for printing a circuit to produce a printed circuit board which comprises print heads for printing materials. The print heads comprise a conductive material print head containing a conductive material as a conductive material to be printed, and a nonconductive material print head containing a nonconductive material as a nonconductive material to be printed. Further provided is a printing apparatus comprising a table for supporting the substrate, a function head configured to accept installations of the conductive material print head and the nonconductive material print head such that either one of the nonconductive material print head or the conductive material print head is carried on the function head at a given time, or both of the nonconductive material print head and the conductive material print head are simultaneously carried on the function head. Still further provided is a positioner configured to effect a movement of the function head and the table relative to one another. The kit includes a controller configured to accept circuit board parameter data defining a printed circuit board and to operate the function head and the positioner to effect: printing the nonconductive material when the function head has the nonconductive material print head installed to form printed conductive items; printing the conductive material when the function head has the conductive material print head installed to form printed nonconductive items, wherein the printed nonconductive items and the printed conductive items are defined by the circuit board parameter data. The controller also includes a parameter database storing data points comprising parameter data and being further configured to: produce a predicted performance of the printed conductive items for operator evaluation, prior to actual printing, by processing the stored parameter data based on the circuit board parameter data; accept operator input to provide revised circuit board parameter data and produce another predicted performance of the printed conductive items; and effect actual printing of the printed conductive items based on the revised circuit board parameter data.
In a still further embodiment of the above the parameter data base includes stored material quality parameters and material identifying data for available print materials, and the controller is configured to accept conductive material parameters of the conductive material to be printed including material identifying data of the conductive material to be printed.
Another feature of the above embodiment is provided wherein the circuit board parameter data includes design parameters defining the printed conductive items, the stored material quality parameters include past measured conductive parameters of past printed conductive items, and the controller is configured to provide the predicted performance of the printed conductive items based on the past measured conductive parameters.
Still further the above embodiment is optionally provided wherein the controller is configured to filter the past measured conductive parameters using the material identifying data of the conductive material to be printed and use resultant filtered past measured conductive parameters to provide the predicted performance of the printed conductive items. In a further variation the stored material quality parameters include material age parameters of available material used to print the past printed conductive items, the controller is configured to further filter the filtered past measured conductive parameters using the material identifying data included in the conductive material parameters of the conductive material to be printed and use resultant further filtered past measured conductive parameters to provide the predicted performance of the printed conductive items.
Yet another embodiment includes a variation of the above kit wherein the parameter data of the data points comprises fabrication slice parameters, material quality parameters of conductive materials used, and past measured design parameters of past printed conductive items, the circuit board parameters comprise design parameters and material quality parameters of the conductive material to be printed, and the controller is configured to process the process parameter data of the data points based on the design parameters of the circuit board parameters to produce optimized fabrication slice parameters.
Another embodiment of the above kit is provided wherein the material quality parameters of the data points include an material age parameter, the material quality parameters of the conductive material to be printed include a material to be printed age parameter, and the controller is further configured to process parameter data of the data points based on the design parameters of the circuit board parameters and the material to be printed age parameter to produce optimized fabrication slice parameters.
The above, and other objects, features and advantages of the present disclosure will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. The present disclosure is considered to include all functional combinations ofthe above described features and corresponding descriptions contained herein, and all combinations of further features described herein, and is not limited to the particular structural embodiments shown in the figures as examples. The scope and spirit of the present disclosure is considered to include modifications as may be made by those skilled in the art having the benefit of the present disclosure which substitute, for elements presented in the claims, devices or structures upon which the claim language reads or which are equivalent thereto, and which produce substantially the same results associated with those corresponding examples identified in this disclosure for purposes of the operation of this disclosure. Additionally, the scope and spirit of the present disclosure is intended to be defined by the scope of the claim language itself and equivalents thereto without incorporation of structural or functional limitations discussed in the specification which are not referred to in the claim language itself.
The foregoing is a summary and thus contains, by necessity, simplifications, generalizations, and omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Additional features and advantages of various embodiments of the present disclosure will be set forth in part in the non-limiting description that follows, and in part, will be apparent from the non-limiting drawings, or may be learned by practice of various embodiments. The objectives and other advantages of various embodiments will be realized and attained by means of the elements and combinations particularly pointed out in the description and appended claims.
In part, other aspects, features, benefits and advantages of embodiments of the present disclosure will be apparent with regard to the following description, appended claims and accompanying drawings wherein:
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities of ingredients, percentages or proportions ofmaterials, reaction conditions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the embodiments of the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a range of “1 to 10” includes any and all subranges between (and including) the minimum value of 1 and the maximum value of 10, that is, any and all subranges having a minimum value of equal to or greater than 1 and a maximum value of equal to or less than 10, e.g., 5.5 to 10.
It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural referents unless expressly and unequivocally limited to one referent. Thus, for example, reference to “a member” includes one, two, three or more members.
Reference will now be made in detail to various embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. While the embodiments of the present disclosure will be described in conjunction with the illustrated embodiments, it will be understood that they are not intended to limit the disclosure to those embodiments. On the contrary, the disclosure is intended to cover all alternatives, modifications, and equivalents, which may be included within the disclosure as defined by the appended claims.
The headings below are not meant to limit the disclosure in any way; embodiments under any one heading may be used in conjunction with embodiments under any other heading.
Referring to
Referring to
The function head 115 optionally mounts to the head mount 110 by mount screw 110c and is aligned by virtue of alignment cones 110a mating with alignment cavities 110b. Other mounting configurations may be adapted without departing from the scope of the present disclosure. The function head 115 has a function module 115a which is optionally configured to effect any or all of ink dispensing, epoxy dispensing, or component placement as is discussed below. The PCB production apparatus 100 is capable of printing circuit traces and/or performing pick-and-place attachment of electrical components. The PCB production apparatus 100 is optionally used for low-cost rapid prototyping and rapid manufacture of complete printed circuit assemblies.
As is elaborated upon below, an embodiment of the PCB production apparatus 100 comprises a function module 115a configured as a printing device for printing conductive material onto the substrate 105. The PCB production apparatus 100 is also optionally capable of positioning circuit components onto the substrate 105 in electrical connection to the conductive material with the function module 115a configured for component mounting as discussed below. In some applications, attachment of circuit components to the substrate 105 and conductive material may include application of a conductive epoxy and the function module 115a is optionally configured with the epoxy dispenser 130. An embodiment of the PCB production apparatus 100 is also capable of applying non-conductive epoxy at specific locations on the substrate 105. If heat curing is optionally used for proper operation of the conductive material and epoxy, an embodiment of the PCB production apparatus 100 optionally includes heater 118 which is a source of heat which is applied under the control of the controller 95. For lightweight and/or flexible substrates, an embodiment of the PCB production apparatus 100 optionally includes a substrate positioning/holding mechanism 121 for temporarily holding substrate 105 to table 104 which, in one embodiment, includes the vacuum source 107. The PCB production apparatus 100 optionally includes the imaging device 108 for implementing a scanning, or digitizing, function for creating a digital model of an arbitrary three dimensional structure for aiding in the positioning of the ink printing and component placement. A further embodiment of the PCB production apparatus 100 optionally includes a material printing function for printing plastic and/or metal structures for supporting and/or enclosing the PCA.
The controller 95 controls functions of the PCB production apparatus 100, including the movement of the head mount 110 relative to substrate 105, and is implemented by software and/or firmware which resides internal to the PCB production apparatus 100, external to the PCB production apparatus 100, or split between the two, where some functions reside external to the PCB production apparatus 100 and some functions reside internal to the PCB production apparatus 100. To aid in the readability of this document, all software and/or firmware references related to the operation of the PCB production apparatus 100 will be referred to as firmware. In some cases, firmware will be referring to an application module that is part of the complete the PCB production apparatus system software or the firmware will be referring to application modules that are optionally operated as stand-alone software applications. Firmware will reside in the controller 95 which is integrated into the PCB production apparatus 100. The controller 95 may be any of a microcontroller, a single board computer capable of producing signals to control the movement of head mount 110, or a standalone computer, such as but not limited to a PC, which has an I/O unit configured to control components of the PCB production apparatus 100 such as any one or combination of the x-axis motor 101a, the y-axis motor 102a, the z-axis motor 103a, the function head 115, the imaging device 108, and the pressure source 109.
It will be understood by those skilled in the art that the controller 95, although depicted as a module within the PCB production apparatus 100 in
Referring to
Conductive inks are typically silver and copper-based but could be of any ink that would provide reasonable conductivity for transfer of electrical signals across the conductive traces. An example of a commercially available silver-based conductive ink is Metalon HPS-021LV from Novacentrix. The HPS-021LV has a resistivity of 6.74 E-5 ohm-cm when the ink is cured at 125° C. There are several other manufacturers of conductive inks that are optionally used when printing conductive traces using the ink-printing mechanism 120 described in this disclosure.
The ink-printing mechanism 120 may include a nozzle or tip with an opening for the ink to flow through. The ink-printing mechanism 120 may be capable of having the tip replaced should a larger or smaller width line be required by the circuit.
Other commercially available conductive inks are capable of being printed using standard ink-jet printing techniques. These types of inks are typically based on nano-particles which allow the ink to be ejected from small holes characteristic of a standard ink-jet cartridge or piezeoelectric nozzle. Here the conductive ink is optionally filled in an ink-jet cartridge and the PCB production apparatus 100 controls the release of conductive ink onto the substrate 105.
Movement of the head mount 110 relative to the table 104, is controlled by the controller 95 based on information contained in a digital model or image of a desired conductive trace geometry or circuit layout. Details of the circuit layout is often contained in an industry-standard Gerber file or any other type of file which supports the desired geometry of the conductive traces. File types may include electronic image files including bitmaps (BMP), JPEGs, GIFs and TIFFs to name a few. The position of the head mount 110 is optionally manually controlled by the operator via the controller 95.
At any one time, embodiments of the function head 115 will contain at least one of the following PCB production mechanisms: the ink-printing mechanism 120 in a function head 115-1 of
The function head 115 optionally has a rotation motor 116 (dashed line representation) to rotate the pick-and-place mechanism 140 or the pick-and-place mechanism 140 includes the rotation motor 116 (dashed line representation) to implement a rotation feature to properly position the electrical component onto the substrate 105. Another embodiment has the rotation motor 116 (solid line representation) mounted outside of the function head module 115a, 115b, or 115c so as rotate the whole function head module 115a, 115b, or 115c. Alternatively, the rotation motor 116 (dashed line representation) may be mounted on the function head module 115a, 115b, or 115c so as to rotate the function head module 115a or 115b relative to the function head 115-3, 115-4, or 115-5.
In an embodiment, the function head 115b includes the ink-printing mechanism 120 and the pick-and-place mechanism 140. The function head module 115b optionally has a print mechanism rotation device 129 (dashed line representation) to rotate the printing mechanism 120 or the printing mechanism 120 includes the rotation device 129 (dashed line representation) to implement a rotation feature to orient a print head as discussed below with regard to circuit trace printing. The print head rotation device 129 is optionally embodied as motor but other actuating devices such as solenoids, voice coils or pneumatic actuators operating off the vacuum source may be used. The embodiment of the function head module 115b having the rotation motor 116 (solid line representation) mounted outside of the function head module 115a, 115b, or 115c so as rotate the whole function head module 115a, 115b, or 115c, is also optionally adapted to print head orientation.
The function head module 115b may include several ink-printing mechanisms, one for each printing type, including mechanisms for conductive ink printing, insulator ink printing and epoxy deposition to name a few. The individual printing and deposition mechanisms may share common parts such as a syringe motor or pressure sensor to name a few. In one configuration, the function head module 115b allows substitution of one ink type for another, such as a case when a syringe that contains the conductive ink is replaced with a syringe containing the insulating ink. Having the flexibility to replace ink containers may reduce the total cost of the PCB production apparatus 100.
In some applications, it may be beneficial to have a complete inking mechanism for each type of ink and epoxy. For example, some ink and epoxy products are two-part systems containing a base material and a catalyst. In this case, a separate mechanism is optionally used to apply the two parts to substrate 105. The epoxy may include conductive and non-conductive forms. Conductive epoxy is optionally used for making an electrical contact between the component and the conductive traces. Non-conductive epoxy is optionally used for holding components and devices to the surface of substrate 105 and the conductive traces.
The epoxy is optionally thermally conductive for applications requiring the dissipation of heat. The epoxy will be dispensed using an epoxy-printing mechanism. The epoxy-printing mechanism may be of the same type as the ink-printing mechanism. The epoxy-printing mechanism may be of a different type than the ink-printing mechanism. For example, the ink-printing mechanism may include an ink-jet technology while the epoxy-printing mechanism may include a syringe printing process. Another example may have the ink-printing mechanism using a single tip dispensing process while the epoxy-printing mechanism optionally uses a dual tip dispensing system when a two-part epoxy is optionally used. These are not the only combinations of dispensing types but are used here to describe some possible variations in dispensing techniques.
The substrate 105 is optionally of any type of non-conductive material to which the conductive traces may be firmly attached and cured. The substrate material may be rigid or flexible, for example and not limitation, fiberglass boards, paper, plastic, wood, glass, cloth, or skin. Referring to
The table 104 optionally also includes a three-dimensional form onto which substrate 104 will be held. The form is optionally a shape that is cylindrical, hemispherical, conical or rectangular to name a few, other shapes are also possible. The limitation in the shape form is only dictated by the flexibility of the PCB production apparatus 100 to printing ink onto a complex structure.
The table 104 may be fixed in location relative to an apparatus frame 92 or may physically move in one or more dimensions under the control of the firmware in order to aid in the printing of inks and insulators. The PCB production apparatus 100 as shown in
PCB production techniques produce conductive traces that follow a circuit pattern required for an electronic circuit with details defining the circuit pattern saved in an electronic file. The information contained in the pattern, also called the layout, may be recalled through the firmware from an electronic database and transferred to the apparatus controller 95 by the operator. In typical applications, the layout would be designed and saved using a separate Computer Aided Design (CAD) tool such as Cadence OrCAD, CadSoft Eagle and Mentor Graphics PADS to name a few. In an embodiment of the present disclosure, the CAD tool is optionally integrated as part of the PCB production apparatus firmware. The CAD tools may output the circuit layout in the form ofnative file types, Gerber, or some other standardized file type. For example, a Gerber file is a data file describing the physical layout of a single layer of a printed wiring board. These layout file types may also include Bitmaps (BMP), JPEGs, GIFs and TIFFs to name a few. The Gerber file is an industry standard used in the fabrication of chemically etched and mechanically etched printed wiring boards. To improve the readability of this document, the term Gerber will be used to describe any type of electronic file that describes the layout of a single layer of printed wiring board including vector and image based electronic files. However, it will be understood that the present disclosure includes any other file type defining a circuit layout when using the name Gerber unless explicitly limited to a Gerber file.
To completely describe a PCB, a set of Gerber files is often required including files that may define conductive and non-conductive features of the printed wiring board. These files may also include the physical location of individual components. In a multilayer printed wiring board, several Gerber files are required to describe each layer in the complete board. In general, the generic term “PCB file” will be used hereinafter to refer to a file describing circuit layout features directed to single or multilayer PCB to be manufactured using conventional methods, such as a Gerber file. The term “printed PCB file” will be used to refer to a file configured to control the PCB production apparatus 100 for producing a PCB using the method of the present disclosure for printing circuitry incorporating multiple layers using printing techniques.
Firmware of the controller 95 will optionally include a layout translation module (LTM) 152 to translate the PCB files into instructions for controlling a location of head mount 110 and each of the associated operations of the PCB production apparatus 100 including the ink-printing mechanism 120, epoxy-printing mechanism 130 and the pick-and-place mechanism 140. The LTM 152, implemented by PCB file translation-software, may reside external to the PCB production apparatus 100 or included as part of the firmware. When the translation-software is external to the PCB production apparatus 100, it may reside in a local personal computer, reside in a web-based tool or any other computing device capable of inputting electronic data files and performing the translation from layout of conventional PCB files to files for controlling the PCB production apparatus 100, hereinafter referred to as apparatus layout files (ALFs), which define the conductive and nonconductive geometries and traces to be produced by the PCB production apparatus 100. Taken a further step, the ALFs may subsequently be translated into apparatus control files (ACFs) which are commands for controlling the PCB production apparatus 100 to produce the PCB. The ACFs may be created “on the fly” from the ALFs to control the PCB production apparatus 100 in the manner that interpreters accept source code and effect program functions without first compiling source code.
In an alternative embodiment of the PCB production apparatus 100, the LTM 152 of
A Design Rule Checker module (DRCM) 154 is optionally employed to verify that the CAD file and/or printing instructions is compatible with control of the PCB production apparatus 100 and also within limits for printing conductive and non-conductive traces defined by limits of the PCB production apparatus 100, for example and not limitation, line width, line spacing and overlap. The DRCM 154 may also check the capability for printing conductive epoxy. In an embodiment, the DRCM 154 is included as an option in the CAD software tool. In another embodiment the DRCM 154 is included as part of the firmware so that the PCB production apparatus 100 can check files from CAD tools not specifically equipped to provide files for the PCB production apparatus 100.
In producing two-layer and multi-layer PWBs using the PCB production apparatus 100, it may be necessary to print insulating inks when two or more conductive lines must cross over each without making electrical contact. The insulating ink replaces the function of the built-in isolation achieved with substrate 52 shown in
The LTM 152 optionally creates a list oflocations where insulating ink is to be deposited onto the substrate 105 covering a first circuit feature and preventing electrical connection between the first circuit feature and those that cross over the first circuit feature. The list may include a width and length of the insulator geometry formed by printed insulating ink. Referring to
When examining conventional PCB files which contain layout geometry for two or more different conductive layers in a PWB, it is important to identify lines from separate layers that would cross over, intersect or overlay is some way when printed with conductive ink absent intervening board layer(s) of conventional PWBs. A standard Gerber file includes information contained in the header followed by a description of the geometry. For example, a single trace would have the following text-based file stored in the format of a Gerber file.
Referring to
There a several ways to determine overlap between traces from two or more layers. An imaging method is optionally used to convert the conductive trace 501 to a graphics or image file and compare the information contained in this image file to the information contain in another image file. Another method optionally employed is to mathematically determine the location of the overlap using mathematical techniques known in the industry which compare line segments for overlap or touching. Mathematical techniques must also include aperture inclusion wherein the width of the aperture that runs along the centerline of the trace including the extension beyond the endpoints of the line created by the radius of the aperture at each end.
Referring to
In operation 203, the coordinates of the intersection are determined based on the technique used to find the intersection. In an embodiment of operation 203, the area of the first overlap 503 is stored as another image file based on the total number of pixels and layout of the pixels. Another embodiment of operation 203 includes a technique to store the first overlap 503 in terms of a centroid, length and width. As not all overlaps are rectangular, as in the case when diagonal lines are present, the geometry of a complex overlap may be stored.
Once the overlap, i.e., intersection, is determined, operation 204 is effected wherein a new geometry for an insulator is created that matches or is slightly larger than the geometry of the overlap 503. When printing two conductive traces that should be electrically isolated, it is advantageous to oversize the overlap geometry to prevent the possibility that the two conductive traces will short together. Referring to
Referring to
Returning to
The insulator geometry operation 204 uses the overlap geometry determined using image-based techniques or mathematically techniques in operations 202 and 203. An example of the insulator geometry is the insulator patch 504 of
The creation of the insulator geometry of the insulating patch 504 is performed by the LTM 152 in operation 204 or is optionally performed in a software tool that routes the layout. Once the layout information for the insulating patch is determined, it is stored as an image file or as a Gerber file, for example purposes only as other known commercial standards for files defining multilayer circuit boards are optionally used by the PCB production apparatus 100 during the multilayer printing process. If the layout information is determined by the LTM 152, it is optionally used to directly control the printing-mechanisms in apparatus.
Another form of insulating two conductive layers is to print an entire region of insulating ink between the two conductive layers. Referring to
Referring to
Referring to
Referring to
Referring to
In printing two-layer and multi-layer PWBs using the PCB production apparatus 100, the need to print conductive connections between conductive traces arises. These connections replace the drilled vias, 60a and 60b, in a traditional PWB as described above in relation to
Typically optionally used by traditional PCB vendors, drilled via holes are often located at a center of a circular pad similar to the pads 72 of
Referring to
Another method optionally effected by the LTM 152 is to combine the layouts of first conductive trace 230 and first conductive pad 231 and second conductive trace 233 and second conductive pad 234 into a combined conductive trace and print both sets of conductive geometries at the same time in which the layout would not need the conductive pads and a continuous configuration having the outline shown in
Yet another method where there is no drill file but there is an image or a Gerber (or analogous type file) that shows the hole locations and the hole size the LTM is programmed to identify the location for the overlap between the two conductive layers. Another alternative operation includes the use of the pad geometries to not print the overlap area but instead print the diameter of the drill listed in the drill file. Although the total surface area printed between the two conductors is less using the drill file dimension, it suffices to provide and interconnection between layers.
In traditional multilayer PWB, a via hole is drilled through the entire stackup of conductive layers and substrates. To ensure the plating process adheres within the drilled hole, conductive circular pads are typically located on each conductive layer for each plated through hole to be drilled through thus allowing tolerance for the drilling alignment. In some traditional PWB applications, the via hole is only drilled through the layers that require direct electrical connection(s). These types of vias are called “blind-hole vias” and are typically more expensive to manufacture using traditional methods. Using the PCB production apparatus 100, printing the equivalent of a blind-hole via is easily created by only printing the electrical connection between those conductive traces. Using the PCB production apparatus 100, printing the equivalent of a blind-via would not add any additional cost to the printed PWB and is advantageous as it will reduce an amount of conductive ink that is to be printed by eliminating the typical circular pads, 231 and 234, from those layers that would have been used in a standard chemically etched PCB process. Instead, a configuration, as shown in
Software layout tools that generate Gerber files will also generate a drill file that contains information regarding plated-through-hole via connections between layers. Apparatus may use information in the drill file to determine the (x,y) locations where electrical connections are to be made and also where to create clearance holes in a non-conductive layer to allow these connections. Referring to
When printing conductive and non-conductive inks in order to connect first conductive trace 531 to second conductive trace 532 only on the area of via hole center (x5,y5), the process begins by identifying the (x5,y5) location of via hole using the drill file associated with the PWB. The second operation is to print first conductive trace 531.
The third operation in the process is to print insulating patch 530. Insulating patch 530 includes first clearance hole 533 which exposes a portion of first conductive trace 531 in the area of via hole center (x5,y5). Insulating patch 530 is optionally designed to cover all other conductive traces associated with the layer containing first conductive trace 531 or only a portion of other conductive traces associated with the layer containing first conductive traces. Alternatively, insulating patch 530 may contain other clearance holes associated with other connections between two conductive layers. Alternatively, insulating patch 530 can completely cover the substrate and all remaining conductive traces associated with the layer containing first conductive trace 531 with the exception of first clearance hole 533 which exposes a portion of first conductive trace 531 and any other clearance holes used to connect two layers.
The fourth operation in the process is to print second conductive trace 532 on top of insulating patch 530. As second conductive trace 532 overlaps first conductive trace 531 in the area of (x5, y5), there will be an electrical connection between first conductive trace 531 and second conductive trace 532. The diameter of first clearance hole 533 is optionally set to a nominal value determined automatically or entered by the operator. Alternatively, the diameter of first clearance hole 533 is optionally determined using pad diameter information contained in Gerber file 541 and/or Gerber file 542. In one case, the diameter of first clearance hole 533 will be set to the largest diameter of pad connected to first conductive trace 531 or second conductive trace 532. In another case, the diameter of first clearance hole 533 will be set to a diameter larger than the largest pad connected to first conductive trace 531 or second conductive trace 532. In this case, the diameter of first clearance hole 533 is optionally oversized to take up printing tolerances while still exposing the conductive ink associated with first conductive trace 531 and second conductive trace 532. Typically oversize diameters will be 10 mils larger than the largest pad connected to first conductive trace 531 or second conductive trace 532.
In an alternative embodiment of the PCB production apparatus 100, the LTM 152 of
To conserve ink, the GERBER file information may be used to create a framework of the original circuit trace. In this case, the translation software may find the center line or an edge line to print the conductive ink. By examining the GERBER file, the start and end points of a conductive line are optionally determined and the printed line width is optionally optimized to reduce the overall cost of the printed circuit.
Another way to conserve ink it to create a mesh in areas that were originally specified as solid conductive regions. For example
When printing inks, the function head 115 including the ink-printing mechanism 120 must move around the substrate under the control of the apparatus firmware. The LTM 152 analyzes the PCB file to create a configuration which is effective to move the function head with the minimum travel path. For example,
In the PCB production apparatus 100 that optionally includes a pick and place function, the function head 115 would include the pick-and-place mechanism 140. In one configuration, the pick-and-place mechanism 140 includes a vacuum pickup, vacuum tip, and/or suction cup, for temporarily holding an electrical component while the component is positioned onto the substrate. The pick-and-place mechanism 140, either in part or whole, may be detachable from the function head 115 in order to share common components with the ink-printing mechanism(s) 120. In the preferred configuration, the pick-and-place mechanism 140 is located adjacent to the printing mechanism(s). The function head 115 optionally has a rotation motor 116 to rotate the pick-and-place mechanism 140 or the pick-and-place mechanism 140 includes the rotation motor 116 to implement a rotation feature to properly position the electrical component onto the substrate 105. The minimum rotation capability would be 0-degrees and 90-degrees but other rotation angles may be possible. In one embodiment, or the function head 115 has the rotation motor 116 arranged to rotate the electrical component prior to placement on the substrate. Another embodiment has the rotation motor 116 arranged to rotate the entire function head module 115a.
The function head module 115b optionally includes a motor, a solenoid, field coil or other controllable actuator, or multiples thereof, set a distance between a selected one of the mechanisms 120, 130, or 140, and the table 104. For example, a solenoid may be used to lower a height of the ink-printing-mechanism 120 such that the insulator-printing mechanism 120′, pick-and-place mechanism 140 and epoxy-printing mechanism 130, will maintain a larger distance to the surface of the table 104.
The printing table 104 optionally includes the heater 118 embodied as a heating element to elevate the temperature of the substrate 105 in order to accelerate curing of inks and epoxies. For example, the Novacentrix HPS-021LV has a cure time of 30 minutes when the ink is held at 125 degrees-C. The apparatus-firmware would control the heating element in the printing table. The temperature control optionally employs a temperature sensor 118s which is monitored by the controller 95 for effecting correct curing of epoxies and inks
An ink-flow sensor 119 is optionally used to measure when the ink has begun to flow and has reached the substrate. The sensor 119 is optionally optically-based or measurement based. In an embodiment, a measurement based sensor 119 measures a resistance and/or capacitance between an ink dispensing tip and the substrate 105. For example, the dispensing tip is optionally metallic and with a sensor connected between the tip and the substrate, a relative change in the resistance and/or capacitance is measured with and without ink flowing between the tip and the substrate.
The pick-and-place mechanism 140 is optionally integrated in the PCB production apparatus 100 and operates in conjunction with a component feed mechanism 122. Referring to
Referring to
Referring to
In another configuration, a tray or trays 124a have a location that is fixed once the trays are inserted into the apparatus. In another configuration, a tray 124a may be ejected from the component feed mechanism 122 once the component is removed from the tray 124a. In this configuration a next tray 124a is optionally moved into the location of the tray 124a that was previously ejected. This configuration allows the pick-and-place mechanism 140 the option to pick up components in the same location.
Referring to
Referring to
In contrast to tray 124a, the multi-cavity tray, 124c or 124d, optionally has one or more sides open to aid the operator in placing the parts into the multi-cavity trays, 124c or 124d, which are shown as having one open side for exemplary purposes and are not so limited. The operator may manually place a part into the multi-cavity trays, 124c or 124d, and slide the component into a corner of the multi-cavity trays, 124c or 124d. Based on a location of a corner of tray 124a, or if more than one compartment, corners of the tray, 124c or 124d, the CMCM 127 is able to position the pick-and-place mechanism 140 near an appropriate corner in order to pick up the component. The operator may enter a location of each component into a table displayed on a computer screen or other visual interface device. The preferred location of the component on the tray is optionally determined by the CMCM 127. In this case, the CMCM 127 will display one or more of component identification, the associated compartment location, component orientation, and compartment corner for positioning the component. When guided by CMCM 127, there may be an ideal tray location for each part which improves the speed of the pick-and-place operation. For example, if the printed circuit includes a resistor located in the bottom region of the circuit and a capacitor in the upper region of the circuit, the ideal location for the resistor would be at the lower portion of the tray and the capacitor at the upper region of the tray. In this way, the movement of the pick-and-place mechanism 140 is controlled to reduce a total length of movement.
Referring to
In most integrated circuits having multiple pins, the package includes a marked feature to highlight the location of one of the pins, typically pin 1.
For components with two terminals, such as diodes, the “dot” convention is typically not used. In this case, components manufacturers rely on a variety of different marking schemes to describe the direction of current flow from anode to cathode. When placing this type of device onto a tray, an identifiable mark is optionally placed on the tray to aid the operator as to the proper orientation for the component. One such mark is optionally a typical schematic symbol for a diode. The CMCM 127 may also provide a graphical image or text based description of the proper orientation for the component when placed in the tray.
To eliminate the need for accurately placing a component into a tray for pickup by the pick-and-place mechanism 140, or when improved accuracy is needed when placing a component onto a substrate, optionally provided is the imaging device 108, such as a camera, for providing the CMCM 127 with a method to “visually” identify a components orientation and offset in order to rotate the component prior to placement onto the substrate 105 or to offset the component when placing the component on the substrate 105. The imaging device 108 is optionally located above, below or to the side of the component in the tray. The imaging device 108 is optionally located separate from the tray and the pick-and-place mechanism 140 will pick up the component from the tray and then move the component into the visual field of the imaging device 108. In this case, the imaging device 108 is optionally located above, below or to the side of the component as the pick-and-place mechanism 140 moves the component into the field of view of the imaging device 108.
An embodiment of PCB production apparatus 100 has a camera system as the imaging device 108 placed adjacent to the tray pointing upward. The pick-and-place mechanism 140 picks up the component from the tray and move the component over a camera lens. The camera image is passed to an algorithm to detect edges and/or a center of the component. Any rotation of the component relative to a desired position on the substrate 105 is corrected to within a given tolerance by the PCB production apparatus 100 prior to placement on the substrate 105. The pick-and-place mechanism 140 is optionally capable of rotating the component as discussed herein with regard to the rotation motor 116. In an advantageous embodiment, the pick-and-place mechanism 140 can rotate the part by at least 90 degrees. More preferably the pick-and-place mechanism 140 can rotate the part by at least 180 degrees. Even more preferably the pick-and-place mechanism 140 can rotate the component over a 360 degree angle. The camera is optionally any relatively low cost camera such as the LinkSprite JPEG 2MP Color Camera. As most cameras have a long focal point, a macro lens is optionally placed over the lens of the camera system in order to be able to focus the camera on the component which can be fairly close to the imaging system.
In another embodiment of the present disclosure, the operator manually places components onto the tray and then the pick-and-place mechanism 140 picks up the components and moves them to a separate location or “holding area” for temporary storage until they can be placed on the substrate 105 at a later time. One benefit to this action is that the operator may place all the necessary components into the apparatus during one step in the total print and assembly process. For example, by placing all the components into the PCB production apparatus 100 during the initial phase of the operation, all printing and component assembly can occur without any further intervention by the operator. Another benefit for the implementation of a holding area is to reduce the complexity of the tray system which optionally allows for a tray with a single compartment. Another benefit to the holding location is that a tape-and-reel system is optionally added to PCB production apparatus 100 where the tape and reel system only requires a single reel handling mechanism.
For the pick-and-place mechanism 140, the LTM 152 may also create a list of an order for which the components would be placed onto the substrate. The list may be provided to the operator prior to inserting the components into the PCB production apparatus 100. In this way the components may be inserted in the optimized order for facilitating the pick and place process. As another option would allow the operator to enter a list of components in an order in which the operator inserted the components into the PCB production apparatus 100. The component mounting control module (CMCM) 127, implemented by the controller 95 and shown in
In a standard PCB process using two or more conductive layers, it is possible to place and solder components to the outermost two layers on the PWB. As there is at least one insulating layer between these conductive layers, components are placed at or near the same (x,y) coordinates so there could be a some amount of overlap between the components without interfering with each other. When using PCB production apparatus 100, all components are placed on one layer of the substrate. For PCB production apparatus 100, the components are on one side and must be properly positioned so there is not overlap between the components and their respective pads.
Referring to
In an embodiment of the LTM 152, conductive traces are positioned to run under the components and these conductive traces will be printed on the same conductive layer as the connection pads. In cases where it is expected that the PWB will exposed to the environment, the LTM 152 will automatically create a PCB file, for example and not limitation, a Gerber file, that will include a non-conductive pad to completely cover the conductive line that is printed under the component so that the conductive line will not oxidize when exposed to the environment. The components and associated connection pads are spaced far enough apart so there is no overlap while also providing space for connecting conductive traces. For example, spacing connection pads by at least 30 mils will allow at least one conductive trace to be routed between two components assuming that a printed conductive trace has a minimum width of 10 mils and the spacing between conductive elements is a minimum of 10 mils on either side of a conductive line. The LTM 152 follows guidelines set for component spacing which may include using a default or operator-generated value for the component spacing.
In an alternative embodiment of the PCB production apparatus 100, the LTM 152 of
PCB production apparatus 100 optionally includes a plastic-extruder 123 for printing a plastic housing over the substrate. In one configuration, the plastic-extruder 123 is part of the function head 115. The plastic-extruder 123 is similar to 3-D printers available on the commercial market. The plastic-extruder 123 is optionally used to fabricate the substrate on which the conductive traces and components are placed. Printing the substrate allows for a variety of complex three dimensional shapes to be fabricated and also provides a more accurate placement of the components and printing the conductive and non-conductive traces as the same apparatus head is used for all types of material printing.
The outer surface of a complex three dimensional shape or form can be modeled and included as part of the printing and assembly process. The surface model would be used to position the ink-printing mechanism over the substrate. The surface model can be an electronic file that is used by the LTM for the printing and assembly process. The PCB production apparatus 100 may include an integrated surface scanner or digitizer, referred here as the surface-scanner, used to measure the three dimensional substrate and/or three dimensional substrate-form in order to create a model of the surface contour for any three dimensional object.
PCB production apparatus 100 may also have a mechanism for printing a protective coating over the surface of the circuit. In some applications, it may be important to protect the surface from scratches. In this case, a protective-ink mechanism 120 is included in PCB production apparatus 100, and may be part of the function head 115. Some protective coatings, such as the commercially available “Humiseal”, can provide a conformal coating and shield against moisture, humidity and chemicals. These coating materials may be of type acrylic, polyurethane, silicone to name a few.
PCB production apparatus 100 optionally includes the imaging device 108 embodied as a camera for identifying to orientation of components used during the pick-and-place process. For example, there may be a slight rotation of the parts in the component holder and when the pick-and-place mechanism 140 picks up the component, the camera is optionally used by the CMCM 127 to identify if the component is properly positioned for placement onto the substrate.
In addition to non-conductive substrates, the substrate material is optionally electrically conductive, semiconductive or metallic. When using these types of conductive or partially conductive substrates, the PCM 128 would first print a layer of insulating ink prior to printing the electrically conductive circuit traces using conductive ink. Substrates that are metallic and electrically conductive are optionally used to improve the thermal dissipation of high power electrical components and assemblies such as high power transistors and light emitting diode (LEDs). Printing a thin insulating layer between the electrically conductive circuit traces and the substrate may substantially improve the thermal performance of the circuit where excessive heat generated by the electrical components is transmitted through the thin layer of insulating material to the metallic substrate and dissipated away from the components. The technique of printing a thin layer of insulation ink over a metallic substrate would also be useful in applications that do not require high thermal dissipation but optionally uses a high strength substrate.
As discussed above, the PCB production apparatus 100 optionally includes a substrate-positioning/holding mechanism (SPHM) 121 to aid the operator in properly positioning the substrate 105 onto the printing table. The SPHM 121 may be a simple cross hair or grid located across the surface of the printing table. The SPHM 121 may be a raised edge or a combination of raised edges in which the operator can push the substrate 105 into the proper location known to the PCB production apparatus 100. The SPHM 121 may be useful to identify a common point for the PCB production apparatus 100 to use as an absolute reference to the circuit geometries that will be printed. The SPHM 121 is optionally removable and placed within the PCB production apparatus 100 once the substrate 105 is properly positioned. The SPHM 121 is optionally an optical-based or sensor-based sub-system to automatically locate edges of the substrate 105 once the substrate 105 is placed on the printing table. In this case, the position of the substrate 105 is optionally arbitrary and the PCB production apparatus 100 will automatically locate the substrate 105 on the printing table.
The PCB production apparatus 100 may include the SPHM 121 to temporarily hold the substrate 105 in place during the printing and assembly process. The substrate-holding mechanism 121 is optionally clips, weights or any object capable of temporarily holding the substrate 105 in position. The substrate-holding mechanism 121 may be a vacuum based sub-system which is optionally activated once the substrate 105 is properly positioned onto the printing table.
Substrates are not limited to planar, or flat, geometries. The substrate 105 can also be any three dimensional object which would support the conductive ink and/or associated circuit components. Any complex surface geometry is modeled and included as part of the printing and assembly process. The surface model would be used to position the ink-printing 120 over the substrate 105. PCB production apparatus 100 may include an integrated scanner or digitizer, referred to herein as the surface-scanner as one of the imaging devices 108, which is used to measure the three dimensional substrate 105 and/or three dimensional substrate-form in order to create a model of the surface contour for any three dimensional object.
When printing conductive inks using the ink printing mechanism 120 embodied as a syringe, inkjet, piezoelectric or other means of dispensing conductive inks onto a substrate 105, it may be desired to layer the ink in order to build up enough cross section for use in circuit applications requiring high electrical current. In order to constrain conductive traces to a narrow width while providing a thickness to the total cross section of the printed conductive line, an initial printing process using non-conductive inks provide support during the layering of the conductive ink. Referring to
Conductive Ink Printing without Drying the Print Surface.
When printing conductive inks using techniques such as syringe printing, inkjet printing, piezoelectric printing and others, it is important that the ink is not allowed to dry at or near the interface where the ink leaves the printing mechanism and the air. Often, a printing process pf the PCM 128 moves enough material to prevent clogging of the printing mechanism 120 or epoxy printing mechanism 130 but in applications where the printing mechanisms, 120 or 130, must move across a large distance, it is possible that the ink may dry at the air interface. One way to prevent drying would be to temporarily cover or cap the printing mechanism, 120 or 130 until the mechanism is at or near the desired printing site. Another technique would be to have a wiping mechanism that wipes a surface of the printing mechanism, 120 or 130, and removes dried ink from the printing mechanism, 120 or 130. The wiping action could include a moist surface to wet the dried ink enough to become fluid. It is known that many conductive inks, including silver nanoparticle inks, are water based. In this case wiping the printing mechanism, 120 or 130, with a damp sponge, cloth or other material prevents the printing mechanism, 120 or 130, from becoming permanently clogged. Thus, an embodiment of the PCB production apparatus 100 optionally has a clog prevention device 138 including one, or both, of a wiping mechanism or capping mechanism, which is controlled by the PCM 128.
Another embodiment of a method optionally employed to prevent the printing mechanism 120 from becoming clogged and implemented by the PCM 128 is to reduce the time between printing and not printing. In this case, the conductive traces are optionally printed in a preferred sequence in order to minimize the time when the printing mechanism is not printing. In a typical application, the printing mechanism's printing surface may have a dimension less than the circuit line dimension thus requiring the printing mechanism 120 to make several passes over the circuit in order to complete the circuit. For example,
If the horizontal spacing between the upper ends of lines EP1-EP2 and EP4-EP4 are too far enough apart, it may be possible that the ink would dry on the surface of the printing mechanism 120 creating a condition of clogging the holes in the printing. It would then be difficult to print the top of line EP3-EP4. In this case it may be optionally used to wipe the surface of the printing mechanism 120 prior to printing line EP3-EP4 or cover the printing mechanism 120 between the printing of line EP1-EP2 and line EP3-EP4 using the clog prevention device 138.
An embodiment of a method of printing directed to address ink drying examines the circuit and prints the circuit in a path that minimizes dead time between activating the printing mechanism 120. For example,
If the holes in the inkjet cartridge are spaced such that the deposited ink from one hole does not make contact to the deposited ink from an adjacent hole, one solution is an overlap process to offset the printing mechanism 120 equal to a distance less than a diameter of the hole in order to overlap the deposited ink between passes of the printing mechanism 120. This overlap process is optionally used in printing conductive ink, non-conductive ink and protective coatings. The overlap process is optionally used for printing processes requiring the deposition of an ink onto a substrate 105 using a syringe, inkjet, piezoelectric, spray or other inking process where the ink leaving a printing mechanism has a smaller dimension than a circuit feature.
Referring to
In an one embodiment of the PCM 128, printing conductive traces in the direction of current flow in the final circuit is addressed. Following the discussion of
To provide the flexibility to print along the direction of current flow, the printing mechanism 120 is rotated by the print head rotation device 129, or the rotation motor 116 rotating the function head 115, in order to align a nozzle plane to be perpendicular to the direction of current by the PCM 128. Alternatively, the printing mechanism 120 remains fixed and the substrate 105 is rotated by the table 104 being rotated by the table rotator 139, shown in
The PCM 128 controls printing diagonal conductive traces optionally uses a process to ensure that the resistance of the line is below an acceptable level. Printing diagonal conductive traces using any process that ejects ink from a small diameter hole or nozzle, may create limited connections or gaps between the printed dots on the substrate 105. For example,
In an embodiment of the present disclosure, component attachment uses deposition of an electrically conductive epoxy or other electrically conductive glue by the PCM 128. Types of conductive epoxy used, for example and not limitation, are MG Chemicals 8331S and Creative Materials 111-29. The printing of epoxy may be performed with a variety techniques including syringe printing, piezoelectric or other types of printing mechanisms. The location for epoxy deposition requires the identification of component pads by the LTM 152. One technique for locating the epoxy deposition is for the LTM 152 to use information contained in a standard PCB file (GERBER file) for a solder mask. The solder mask file provides the location and pad size used when performing a standard soldering operation for the components. This same file is optionally used for the epoxy printing.
Another method for obtaining the location for epoxy deposition may be accomplished by the LTM 152 using information about the components including the size and orientation of the component. For example, if a resistor of size 1206 is placed in a horizontal orientation, the package size and orientation is optionally used to determine the location of the epoxy deposition. This also includes an amount of epoxy optionally used for proper attachment. Additionally, the location for epoxy deposition is optionally determined by the LTM 152 using circuit features contained in the circuit file provided to the LTM 152. For example, conductive traces that end without connection typically require a connection to a component. These features are optionally used by the LTM 152 to produce instructions controlling the PCM 128 during the epoxy deposition process. As some epoxies are rated for a heat cure which often accelerates the curing process, the PCB production apparatus 100 is optionally equipped with a heater in the form of table heater 118. As some epoxies are rated for a UV cure, the PCB production apparatus 100 is optionally equipped with a UV heater 118a, shown in
The PCM 128 optionally implements deposition of solder paste by the techniques mentioned above for conductive epoxy. In one embodiment of the PCB production apparatus 100, solder paste is applied by the epoxy dispenser 130 to the printed circuit conductive traces prior to placement of the components. The solder paste would be applied using a syringe, piezoelectric or other printing mechanism. The application of solder paste to the substrate 105 uses either the ink printing mechanism 120 or the epoxy dispenser 130, developed for printing inks and epoxy. In another embodiment of the present disclosure, the PCB production apparatus 100 optionally uses a separate sub-system. As mentioned above, the PCB production apparatus 100 optionally includes an integrated heat source such as the UV heater 118a for effecting solder reflow.
It is optionally possible to apply the solder paste using a silk screen process where a solder mask is placed over the substrate 105, which includes the previously printed circuit features, and the solder is pulled across the solder mask to place the solder paste onto the conductive line. This process is fairly standard in the industry but is unique to a system that includes all the printing and attachment processes. The solder paste would be reflowed during a separate heating process of the substrate 105. As mentioned above, the PCB production apparatus 100 optionally includes an integrated heat source such as the UV heater 118a.
The PCM 128 optionally implements a process for deposition of non-conductive epoxy. For example, when attaching large components or with applications requiring a flexible substrate 105, attachment of components using a non-conductive epoxy aids the component attachment to the substrate 105. In an embodiment of the process, the deposition of non-conductive epoxy is done before the deposition of conductive epoxy or solder paste. Alternately, the non-conductive epoxy is deposited after the deposition of the conductive material. In either case, the deposition of conductive and non-conductive epoxies and/solder onto the substrate 105 occurs prior to the placement of the one or more components onto the substrate 105.
When printing a multilayered circuit, the process begins with two or more files containing the individual circuit conductive traces and features. These files are typical of a GERBER format but may be of any PCB file type that properly describes circuit features in each of the layers. In one embodiment of the LTM 152, the files are examined and the locations of the circuit crossovers are determined as discussed above. This identification process may be performed internal to the LTM 152 or external to the PCB production apparatus 100. Once locations of crossovers are identified, the LTM 152 optionally creates a new single layer circuit layout which combines all the circuit conductive traces and features from the layers with the exception of breaks or discontinuities at the location of the crossovers. This process may accelerate the printing process by producing a single layer board that is optionally printed in one pass of the printing mechanism. To produce the completed board, a secondary process of layering non-conductive and conductive layers only in the areas of the crossovers of cross-overs is implemented.
In a standard printed wiring board process, each layer is etched onto the surface of a laminated substrate. In this case the crossovers are electrically isolated by the non-conductive substrate material between the various layers. When creating a printed wiring board using a printing process as part of this disclosure, the various layers are compared and crossovers are identified. Once crossovers are identified, different layers are optionally combined into a single layer for printing. In this case, the crossover information is preserved and used during the secondary process.
Referring to
The next step is to reconnect the printed conductive traces that have a break. In one embodiment shown in
The process of printing conductive inks is optionally optimized to produce a line with a specified resistance. This technique not only produces an electrical connection between two points but also eliminates need to add a separate resistor to the printed circuit.
The function head 115 is optionally used during a calibration process to set to location of an absolute substrate or system position, i.e., table position. This location may be considered the (X, Y, Z)=(0, 0, 0) location or “home” location. Using a common function head 115, the calibration process may only need to be performed once for all inking, deposition, and pick-and-place functions. A Z-axis or vertical calibration is optionally performed periodically before and/or during the printing process or may be performed continuously by means of a sensor which monitors the top of the substrate and printed wiring board. The sensor may include a mechanical “feeler” or by optical means.
Referring to
Predefined built-in offsets for function heads are based on ideal mechanical dimensions of the printing mechanism 120, the epoxy mechanism 130, or the component placement mechanism. For example, the table 104 has an inherent zero position with relation to which operation points of the function heads are to be coordinated. The positioner 90 is optionally zeroed with respect to the inherent zero position such that the motors are operated to position the head mount 110 at a predetermined spatial relationship to the inherent zero position of the table 104. At this position, operating positions in each of the three axes of the positioner 90 are set to zero meaning that, when the controller 95 commands the positioner 95 to move to position 0, 0, 0, for example, it returns to the inherent zero position. This may be done either in the controller 95 as a final adjustment to commands or within the positioner 90.
Each of the function heads has an inherent built-in offset such that when the positioner actually moves the operation point of a given function head to the inherent origin, positions recognized by the positioner 90 and controller 95 will reflect the built-in offsets of the particular function head which will be called for clarity purposes, F1X, F1Y, and F1Z, wherein the designation F1 indicates the particular function head, i.e., function head “F1.” When the positioner 90 moves the operation point of the function head to the inherent origin, the controller 95 has directed the positioner to −F1X, −F1Y, and −F1Z. In operation, the controller 95 will make these adjustments in the final commands sent to the positioner 90 and the adjustments will be based on which function head is in use. Optionally, the function heads will include indicia which may be electronically or manually communicated to the controller 95 so that the controller 95 associates the particular function head with stored built-in offsets. This is optionally done by optically reading indicia on the function head using the imaging device 108, or electronically reading the indicia via any of hardwired, RF, such as for example and not limitation, an RFID tag, or infrared.
In practice, the actual built-in offsets will vary based on machining tolerances. If tolerances are wide enough in the particular application to producing a circuit board, use of the built-in offsets may be suffice an no further alignment is necessary. When tolerances are tighter, a calibration is done to effect accurate registration of the function heads with relation to either the substrate or the table.
An embodiment of an alignment method implemented by an alignment module (AM) 142 of the controller 95, shown in
Once the registration mark is made by the printing mechanism 120, the epoxy mechanism 130 is next operated to print an epoxy dot at the registration mark made by the ink printing mechanism 120 based on predefined built-in relative offsets between the printing mechanism 120 and the epoxy mechanism 130 and the substrate offsets. However, variations of function head dimensions, and the various mechanism included in the function head, will invariably result in a misalignment of the epoxy dot with the registration mark. In an embodiment of the PCB production apparatus 100, the imaging device 108 is mounted so as to view the registration mark and is read by the alignment module 142 of the controller 95. The X and Y offsets are then determined from the image and stored as head component offsets which are added to the built-in relative offsets of the mechanisms 120, 130, or 140. Alternatively, the offsets may be manually entered and confirmed. In subsequent operations the head component offsets and built-in offsets are used to effect operations.
The component placement mechanism 140 is also calibrated in a similar procedure wherein a standard component or a dummy component is placed by the component placement mechanism 140 so a predefined point of the standard or dummy component is to align with the registration. Head component offsets of the predefined point from the registration mark are then determined and entered, either automatically or manually.
Another embodiment of the above registration mark does not require printing an initial registration mark using the printing mechanism. Instead, a feature on the substrate 105, for example a corner or an indicia on the substrate is used in place of the registration mark. Each of the printing mechanism 120, the epoxy mechanism 130, and the component placement mechanism 140 will have the operation point thereof positioned aligned with the feature. The operation point is optionally, for example and not limitation, a tip of a syringe of the epoxy printing mechanism 130, a tip of a suction nozzle of the component placement device 140, or a print jet orifice or an alignment mark or protrusion of the ink printing mechanism 120. When each of the operations points are aligned with the feature, a position reading of the positioner is taken. If alignment is perfect, all the position readings will be same. However, variations in alignment will result in the readings being different. Several calibration option exist.
A first option is to use a relative offset correction that corrects align of the function head module operation points with respect to each other. One of the readings taken when the operation point of a selected function head is aligned with the feature is taken as a base line with the head component offset being the raw position readings from the positioner 90. The reading selected functions as a baseline taken as 0, 0, 0, i.e., a base origin, and then store differences between the position readings of the other function head components and that of the selected baseline component as head component offsets to be applied in future operations. Operations are then conducted with the selected function head using 0, 0, 0, as a head component offset, and the differences are stored as the head component offsets of the other function head components. Thus, the relative positions of the function head components are compensated for variations in mechanical dimensions.
Another approach is to store the position readings taken when the alignment with the feature is in place as the head component offsets with respect to the zeroed head mount position. These readings are then used as the head component offsets for each head components. In this method, the head component offsets subsume the built-in offsets of the various head components.
When printing a multilayer PWB using conductive and non-conductive inks, it may be necessary to maintain a relatively flat surface across the entire top of the PWB. For example,
When printing a non-conductive layer between two conductive layers in order to isolate the two conductive layers from making electrical contact, it may be necessary to over print non-conductive layer to guarantee that the non-conductive layer completely covers the first conductive layer or to increase the non-conductive layer height to a functional height required by the circuit. Keeping a count of the number of non-conductive layers printed would be necessary to calculate the approximate thickness of the total non-conductive layer. For example,
In
When creating circuits that require a high current capacity, the selection of a traditional PWB using chemical or mechanical etching processes is usually limited to selecting the thickness of the copper cladding on the FR4 board. Generally, copper clad boards are specified in ½ ounce, 1 ounce and 2 ounce copper thickness. For example, a 1 ounce copper clad board has a copper thickness of 1.4 mils. For the highest current capacity, the more expensive 2 ounce copper cladding is usually selected. The thicker cladding also requires more processing time and cost to chemically etch the PWB. In general, not all the wiring on the PWB requires high current capacity as circuits usually contain a mix of low and high current requirements. For example, a PWB designed for a motor control, would contain high current wiring for the motor drive and lower current wiring for the embedded microcontroller.
In order to reduce the cost of the PWB using printed method, apparatus 100 can print conductive layers with different amount of thicknesses.
In some cases, the outline of the finished PWB is not rectangular. When processing a PWB using traditional methods of chemically or mechanically etching the traces, the copper clad board starts as a square or rectangular form and then the finished PWB is mechanically cut to the desired shape. The shape, or outline, is either specified as another file included in the set of Gerber files, as an image file or can also be determined by examining the geometries of the conductive traces and moving some pre-determined distance from the outmost traces. This process often leads to some material waste especially when the final outline is irregularly shaped. Apparatus 100 can begin with the substrate previously cut to form or apparatus 100 can directly create the substrate by printing a layer of conductive or non-conductive material to the desired outline. Printing the substrate to the desired outline saves time and material by eliminating the need to cut the outline from the rectangular board and discard the waste.
Function heads for printing inks, epoxies and solder paste may include multiple nozzles for producing small dots. It is possible, especially in low-cost piezoelectric print heads and cartridges, that one or more of nozzles become clogged or stop functioning. It is necessary to identify non-functioning nozzle before printing a PWB. In one embodiment, a test pattern is printed on a substrate in order to identify if a nozzle is not functioning properly. The test pattern can be created by individually activating a nozzle and printing a small amount of material. In one embodiment, the operator examines the test pattern and determines which nozzle or nozzles are not functioning and enters the nozzle into the apparatus 100 interface. In another embodiment, apparatus 100 is configured with an optical system that automatically identifies nozzles that do not function. If a nozzle is identified as not working, apparatus 100 may notify the operator on a procedure to correct the problem.
When using integrated circuits with very close lead spacing or when printing two lines very close together, the functional print head may not be able to adequate separation between printed geometries and it may be possible that two printed geometries are not electrically isolated as intended. In this case, a laser or other optical means will be used to burn away portions of a printed geometry to improve the electrical isolation between these geometries. In certain high frequency application, it is important to maintain a controlled impedance of the printed conductive line. The impedance is determined by the line width and several characteristics of the non-conductive material around the printed line. If the conductive line is not the correct width or the width was intentionally printed wider than required, the laser can trim the line to the desired width. Another important property when transmitting high frequency signals along a printed transmission line, is that the majority of the signal current flows on the outside edges of the printed line. Having line edges that are uneven will increase the signal loss as the signal is transmitted through the line. In this case, the laser can be used to clean up the edges of the printed line in order to reduce the signal loss.
A low-cost laser system can use the laser contained in a Bluray disc read/write system though any laser system capable of removing the conductive material would work. In certain low-cost laser units, a focusing lens may be required to obtain a dot size small enough to create the required geometries. In one embodiment, the laser system is a functional head that can be detached from apparatus 100. In another embodiment, the laser is attached to apparatus 100 or may be part of the printing head. The alignment of the laser spot on the PWB may also be included as part of the calibration process mentioned earlier. In this case, a geometry is printed with some identifiable geometry and the laser burns a portion of the geometry to guarantee alignment between the printed geometry and the burned portion. If there is misalignment, the offset can be manually corrected by the operator or automatically corrected by optical means such as a camera mounted to apparatus 100.
In most PCA applications, it is necessary to connect the functional circuit to a battery. It is also often required to epoxy or solder some type of wire, connector or other interface to the PWB to complete the PCA. It is possible to use components based on surface mount technology for these connections but to improve the reliability of these connections, it may be important to utilize components based on “through-hole” technology. In this case, the printed conductive and non-conductive geometries must include a hole through at least a portion of the printed layers. When the PWB is complete, the metallic and possibly non-metallic, wire, tab or other protruding geometry would be pushed into the printed hole and epoxied or soldered into place. Another key feature of this process, is that many of the wires, tabs or other protruding geometries are not necessarily circular and using the printing process of apparatus 100, it is possible to create a hole that is conformal to the geometry of the connection point of the through-hole component. For example, a card edge connector, such as Sullins RBB10DHHN in a 20 pin through-hole connector where each metallic connector lead has a cross sectional geometry that is rectangular at 0.018 inches by 0.012 inches. When using traditional PWB fabrication, the manufacturer suggests drilling holes with 0.04 inches in diameter. With the printing process, the printed holes can be rectangular at approximately 0.025 inches by 0.020 inches.
Traditionally, solder masks are used to protect the conductive lines from oxidation and isolate closely-spaced conductive lines during the process of soldering components, and their associated electrical terminals, to the conductive traces. The traditional solder mask exposes the conductive traces in the areas of solder attachment. The traditional solder mask is generally very thin in height to prevent component tomb stoning during solder reflow operation. Referring to
When printing a PWB with conductive and non-conductive inks using apparatus 100, a non-conductive guide layer may be printed on top of the PWB for the purpose of assisting the placement of electrical component onto the PWB. For example,
The overlap of the first edge 704 can be determined by the geometry of the first conductive pads 702. For example, if the first conductive pads 702 have a geometry of 0.020-inch wide and using an overlap factor of a 10%, then the first edge 704 will overlap the first conductive pads 702 by 0.002-inch. Another option is printing the first edge 704 with a recess relative to the second non-conductive layer 703B thus placing the first edge 704 further away from electrical terminals 706. In this case, the electronic CAD/CAM file associated with the mask layer maintains a recess which by default is 0.002-inch using the Eagle tool.*
To aid in the placement of electrical component 705, the non-conductive guide layer 701 should have a height of at least 20% of the height of electrical component 705. More preferably, the height of non-conductive guide layer 701 should be at least 50% of the height of electrical component 705. For example, a 0602 SMT resistor with a height of 0.018-inch would result in a height of at least 0.0035-inch or more preferably, 0.0088-inch.
As shown in
Alternatively, non-conductive guide layer 701 or non-conductive guide layer 701-1 and non-conductive layer 703B can be printed together from one type of non-conductive material.
The non-conductive guide layers, 701 and 701-1, can be printed using piezoelectric printing methods, syringe printing or any printing technique that can provide an edge for locating electrical component 705 with the electrical terminals 706 in alignment with portions of the first conductive pads 702. In some cases, the location, size and/or edge type of the holes in the non-conductive guide layers, 701 and 701-1, is determined by the LTM 152 based on coordinates of the first conductive pads 702, or a solder mask file. Alternately a CAD tool, such as Eagle, KiCAD, or Altium, would create a Gerber file, or other electronic file, that contains the location, size and/or edge type of the geometry in the non-conductive guide layers, 701 and 701-1.??
In some cases, non-conductive guide layer 701, non-conductive guide layer 701-1 or non-conductive guide layer 701.2 may cover large portions of the PWB 699, PWB 699-1, PWB 699-2 or PWB 699-3 respectively. Alternatively a non-conductive guide layer 701-3 may cover only a portion of the PWB 699-4 as shown in
During printing of conductive traces using apparatus 100, it may be possible that good electrical connection may not be achieved throughout the entire printed trace. For example,
It is possible to direct apparatus 100 to overprint conductive trace 711 once the location of first break 711C is identified by the operator. It is important to note that manually testing the conductive trace immediately following the printing provides an advantage over traditional methods as conductive traces open to the environment immediately begin to oxidize and create a resistance between the conductive trace and the probe tips. The accuracy of the resistance measurement improves when the conductive traces are measured as close to fabrication as possible. Also, important to note, when measuring the electrical performance of a traditional etched multilayer PWB, if a fault is detected along a conductive trace that is embedded within the multilayered stack, repair is impossible as the PWB layers are all laminated together before electrical testing begins. Using Apparatus 100, it is possible to electrically test the performance of each conductive trace before the next layer is printed on top. This process will greatly improve the yield of functional multilayered boards.
The operator may be able to identify the location by visual inspection of conductive trace 711 or the operator may require an instrument that is capable of measuring electrical conductivity between first trace portion 711A and second trace portion 711B. One example of an instrument is an ohmmeter that is capable of measuring the resistance between two test points. In this case, the operator would place one ohmmeter lead on top of first trace portion 711A and a second ohmmeter lead on top of second trace portion 711B. The ohmmeter would report the electrical resistance between the two test points. If the electrical resistance is measured to be higher than expected across the first break 711C, the operator would identify the location using a computer interface to LTM 150. LTM 150 would then return to the location of break 711C and print another layer of conductive ink across the break establishing an adequate electrical connection. The operator would then have the option to retest the electrical connection and repeat the process if necessary.
Referring to the IPC-9252 Guidelines and Requirements for Electrical Testing of Unpopulated Printed Circuit Boards (hereby incorporated by reference), Section 4.4, states that “one hundred percent continuity and isolation electrical test is the confirmation that the actual electrical interconnect of conductive nodes matches a proven reference source, including but not limited to CAD/CAM digital data, master pattern artwork, or released drawings”. An electrical feature that is a continual conductive line may have several features including a variety of lines, pads and via holes. Together, all of these features are defined by a “net” and the information is typically stored in an electronic file such as a Gerber file. The “end of net” is a feature that is a termination point along a conductive net. In order to meet the guidelines contained in IPC-9252 for optimized net list testing.
Traditional test systems measure continuity between pairs of “end of net” features and are operated upon traditionally printed circuit boards following etching and laminating processes. For the example shown in
For example, single printed conductive trace 711 contains a segment that is 0.15″ across moving from first conductive termination 711D to the right angle bend 711F and also contains a segment that is 0.10″ from right angle bend 711F to second conductive termination 711E, The associated Gerber data contained in an electronic Gerber file would be as follows:
With this format, the line “X0Y0D2*” identifies first conductive termination 711D and line “G1X1 5000Y-10000D2*” identifies second conductive termination 711E. These two X-Y locations can be used for positioning test probes for measuring the electrical performance of the entire line following IPC-9252. The Gerber file presented above, the width of the conductive trace is identified by the size of the line aperture using “% ADD10R, 0.025X0.025*%”. In this case, the line width, and associated aperture is rectangular with dimension 0.025″ by 0.025″.
It is possible that CAD/CAM tools may produce a GERBER file that identifies the outside geometry of the conductive trace. For example,
The numeric values extracted from the Gerber commands are listed as absolute coordinates relative to the origin vertex 711-0 with units of “inches”. For example, second vertex 711-2 has a command line resulting in the vertex of X=0 inch and Y=−0.125 inch (0 inch, −0.125 inch). The points are determined by following the Gerber format described in the Ucamco document “The Gerber Format Specification” (hereby incorporated by reference). The following table shows the vertices and their associated x-y coordinates.
Identifying endpoints can be performed with several techniques such as taking differences between coordinates that have one coordinate the same. For example, first vertex 711-1 and second vertex 711-2 have the same x coordinate, and the difference in the y coordinate is 0.0250 inch which is the width of conductive trace 711 and could be recognized as an endpoint to the line. Third vertex 711-3 and sixth vertex 711-6 have the same x coordinate and the different in the y coordinate is 0.1125 inch which is larger than the line width so this can be assume to be a length of conductive trace. Another example with the same y coordinate is fifth vertex 711-5 and sixth vertex 711-6 has a difference in the x coordinate of 0.025 inch which could be an endpoint.
Optionally, using predetermined parameters regarding line widths, the endpoints are identified. Alternatively, the operator may input line widths. Yet another option is that the differences are examined and the line width is determined based on length to width ratios of conductors. Test probes would be placed a distance from the endpoint at least the radius of the test probe. For example, if the test probe has a conductive tip of diameter equal to 0.020 inches, then locating the test probe on top of conductive trace 711 at a distance of 0.010 inch from the endpoint associated with first vertex 711-1 and second vertex 711-2.
Referring to
Preferably, although not required, the LTM 150 organizes the conductive traces in lists corresponding to layers followed by nonconductive area layers to printed as required by either the input file data or the translated data produced by the LTM to facilitate producing the PWB by printing conductive and nonconductive material. That is, a group of conductive traces is printed and tested followed by the printing of nonconductive areas, with this printing sequence being repeated as necessary to complete the PWB. The term “list” is used figuratively in sense that conductive traces are designated for printing in a manner required for functionality of a resultant PWB
In operation 722 the apparatus 100 prints a conductive trace based on the geometry data processed which preferably arranged in a list of conductive traces to be printed during a sequence of conductive printings to be implemented. The conductive trace is printed using conductive ink on a non-conductive substrate or, on a non-conductive area previously printed by apparatus 100 using a non-conductive ink.
In operation 724, the apparatus pauses for the operator to visually inspect the printed conductive trace for breaks or other anomalies. The LTM 150 initiates display of information that the system is paused and questions whether the conductive trace passes visual inspection. The display of information may be on the display 106 which is either integral to the apparatus 100, or external to the apparatus 100 and connected directly or via a computer used to control or interface with the apparatus 100 as previously discussed. In operation 724 apparatus 100 accepts the operator input in the form of a continue command or a reprint command respectively corresponding to the conductive trace passing or failing visual inspection.
When the operator visually detects a flaw in the conductive trace the operator inputs the reprint command in decision operation 724 which directs the apparatus 100 to recall printing data for the last printed conductive trace and again print the conductive trace in operation 728. The process then moves back to operation 724 for visual inspection.
If the operator's visual inspection is acceptable the operator inputs continue in operation 724. It is advantageous to measure the electrical properties of printed conductive traces especially when traces are narrow and defects may not be visually apparent. Other times traces are relatively wide and visual inspection will suffice. The apparatus 100 is optionally set to either proceed to prompt for a resistance pass/fail input, prompt the operator for input as to whether the conductive traces is to be tested, or proceed directly to bypass the resistance test and move on to operation 732. When the apparatus 100 is previously set to perform the resistance testing, operation 726 directs flow to operation 730 based on the setting. Alternatively, the apparatus 100 may be set to prompt the operator as to whether each conductive trace is to be resistance tested in operation 726. A positive operator response directs flow to operation 730 while a negative operator response directs flow to operation 732. When the apparatus 100 is previously set to not perform the resistance testing, operation 726 directs flow to operation 730 based on the setting. It is further an option that the apparatus 100 is configured only for accepting visual confirmation of the conductive traces in which case a positive response in operation 724 results in flow proceeding directly to operation 732 as shown by the dashed flow line.
In operation 730 the apparatus 100 optionally displays an expected value of the resistance of the conductive trace to compare against the operator's measurement. The expected resistance may be calculated by LTM 150 having knowledge of the trace geometry and the conductivity of the conductive ink. The expected resistance may also be located in a database which is retrieved by LTM 150. The apparatus 100 pauses for the operator to manually measure the properties of the trace. The operator may use a basic ohmmeter to measure the resistance of the printed conductive trace. The apparatus 100 awaits confirmation of an acceptable resistance measurement.
Returning to
As an alternative to displaying an expected resistance, the apparatus 100 may simply await confirmation of an acceptable resistance measurement. An nominal value of resistance may simply be assumed for a conductive trace or traces as may be the case where circuitry has high impedance inputs and little current is used, or other situation where a low resistance connection is not required.
If the measured resistance is unacceptable, the operator provides a negative input in operation 730 and flow proceeds to operation 728 wherein that conductive trace is reprinted and flow then proceed to another inspection of the trace. If the operator determines that a reprint is not required, i.e., the resistance measurement is acceptable, flow proceeds to operation 732 wherein the apparatus 100 determines whether there are further conductive traces to be printed in the given group prior to printing of nonconductive material. As noted above, the LTM 150 optionally processes the PWB data to assemble groupings of conductive traces to be printed sequentially prior to a grouping of nonconductive areas to be sequentially printed, with the printing of sequences of conductive traces and sequences of nonconductive areas being repeated until the PWB is complete. If there remain further conductive traces in a grouping, or layer, to be printed, flow returns to operation 722 and a next conductive traces in a sequence is printed.
If the sequence, or layer, of conductive traces to be printed has been completed, operation 732 yields a negative outcome and flow proceeds to operation 734 wherein it is determined whether the processed PWB data next requires printing of nonconductive areas. If so, flow proceeds to operation 736 wherein the LTM 150 moves on to printing non-conductive areas as required. Printing non-conductive areas may be performed automatically after the resistance measurement or LTM 150 may request an input from the operator in order to continue processing the PWB. In a multi-layered PWB, LTM 150 proceeds to the next layer of conductive and non-conductive geometries based on operation 732-738, with operation continuing until the PWB is complete.
It should be noted that measuring electrical connection between two locations on a printed conductive trace can be measured using a variety of techniques. The ohmmeter is a standard measurement technique. Other techniques include applying a voltage and/or current at one location along the printed conductive trace and measuring the voltage and/or current at another location along the trace. The resistance can be determined by using the Ohm's law equation. The operator may also use other instrumentation to measure the electrical performance of the trace including capacitance, inductance, insertion loss, return loss, time domain reflectometry (TDR) or any other measurement technique that can verify that the printed conductive trace is capable of performing the intended function. Thus, while resistance is referenced above, other parameters may be substituted.
When a multilayer PWB is to be printed there may be numerous conductive traces on a single layer and there may be multiple layers. In such situation it may be advantageous to effect conductor testing in groups, or layers, rather than one at a time. Referring to
The process begins in operation 721-1 by the LTM 150 of the apparatus 100 accepting geometry data for a PWB including one or more layers of printed conductive traces and optionally layers of nonconductive material to be printed as discussed above with reference to operation 721. In the case where a multilayer PWB is to be produced the conductors to be printed are grouped in layers as are the nonconductive areas. The LTM 150 organizes the conductive traces in layers followed by nonconductive layers as required by either the input file data or the translated data produced by the LTM to facilitate producing the PWB by printing conductive and nonconductive material.
In operation 722-1 the apparatus 100 prints conductive traces of a layer, or a next layer, based on the geometry data. The conductive trace or traces are printed using conductive ink on a non-conductive substrate or, on a non-conductive area previously printed by apparatus 100 using a non-conductive ink or material. In operation 723 the apparatus displays a layer information on the display 106. Referring to
Referring again to
When the operator detects flawed traces and initiates a reprint in operation 725, flow proceeds to operation 728-1 wherein the LTM150 recalls the geometry data for the failed traces and operates the apparatus 100 to gain print the failed traces. Flow the proceeds back to operation 723 wherein the layer information screen 740 is again displayed. As an option, the display may only display rows for the previously failed conductors in the conductor data table 744. Alternatively, failed conductor rows may be highlighted for soliciting operator input. Still further the full table may be displayed but all conductors not previously indicated as failed may be displayed with the “Pass” indication being affirmative. Other methods may be adopted to simplify subsequent verification operations. As an alternative to displaying an expected resistance in the conductor data table 744, the apparatus 100 may simply await confirmation of an acceptable conductor review.
If the operator determines that a reprint is not required, i.e., the all conductors of the layer are acceptable, flow proceeds to operation 734-1 wherein the apparatus 100 determines whether there is a subsequent layer of nonconductive areas to be printed. If so, flow proceeds to operation 736-1 wherein the LTM 150 moves on to printing a layer of non-conductive areas as required. Alternatively, flow proceeds to operation 738-1 wherein it is determined whether there is further conductive layer to be printed. If so, flow proceeds back to operation 722-1 and another layer of conductors is printed. Similarly, following operation 736-1 printing a nonconductive layer, operation proceeds to operation 738-1.
When further conductive layers remain flow proceeds back to operation 722-1 wherein another layer of conductive traces is printed. Alternatively, no conductive trace layers remain to be printed, the PWB is complete and the process ends.
One type of traditional test system for testing the electrical continuity and electrical isolation of conductive traces is known as a Universal Grid system. These test systems use a single, double or quad-density grid pattern of test points assembled into a fixture and placed in contact with a fabricated PWB. For example, a single-density grid pattern has spacing of 0.1-inch by 0.1-inch resulting in a 100 points/inch-squared density. A quad-density grid has a density of 400 points/inch-squared. These systems are stand-alone and separate from the PWB fabrication equipment and assembly equipment. The universal grid system may make use of a test-file, such as an IPC-D-356 CAD/CAM file, for identifying the location of via holes and pads. These files identify if the feature is located at the top or the bottom of a chemically etched PWB. For a multi-layer PWB, the universal grid system may not be able to identify conductive line problems embedded within the stack-up and does not allow the operator the option to repair the conductive trace as the PWB as the PWB was previously laminated together during PWB fabrication. In this case, when a PWB conductive trace is found faulty, the entire PWB is typically discarded unless a jumper wire is attached external to the PWB. Another type of traditional test system is the Flying Probe-Type system. A flying probe system use robotic probes that are moved across the board for making contact with the conductive traces. Here again, the flying probe may not be able to identify conductive line problems within the multilayered stack-up or does not allow the operator the option to repair the conductive trace as the PWB was previous laminated together and no longer repairable.
Using apparatus 100 for printing a single layered, or multilayered PWB, it is possible to automatically test the electrical performance of a printed conductive trace and automatically correct the printed conductive trace which may include a break or undesired high resistance. Referring to
Referring to
As shown in
The functional portions of the electrical measurement unit 760 may be split with the probe rotation mechanism 763 and probe holder mechanism 762 being mounted to head mount 110 via the function head 115-6 while the electrical test instrument 761 is situated otherwise on the apparatus 100. First probe wire 765B would connect electrical test instrument 761 to first probe tip 765A. First probe wire 765B may include a connector to temporarily disconnect electrical test instrument 761 from first probe tip 765A. Probe holder mechanism 762 may also be temporarily mounted to function head 115 as a separate mechanism. If required, probe rotation mechanism 763 may also be temporarily mounted to function head 115 as a separate mechanism.
A further configuration includes measurement probes 765A and 765B being incorporated into the ink printing mechanism 120 since, as related below, the ink printing mechanism 120 need not make contact with the substrate 105 so the probes may protrude below the ink printing mechanism 120 and selectively make contact with printed conductors by means of vertical movement of the head mount 110. Rather than incorporate into the ink printing mechanism, the probe holder mechanism 762 may be mounted to the ink printing mechanism 120. If required, the probe rotation mechanism 763 may be mounted to ink printing mechanism 120.
Electrical test instrument 761 include types of two-wire and four-wire test systems for measuring the electrical performance of the printed conductive trace. Four-wire test systems are more accurate but require measurement of current and voltage separately. Electrical test instrument 761 also includes measurement types that are capable of measuring the electrical performance of the printed conductive trace which include capacitance, inductance, insertion loss, return loss, time domain reflectometry (TDR) or any other measurement technique that can verify that the printed conductive trace is capable of performing the intended function. For a basic resistance test between two test points, as shown in
Referring to
In the situation that the probe holder mechanism 762 has a probe separation d that is less than the length of a printed conductive trace, two or more electrical measurements are optionally effected as the first test probe 765A and the second test probe 765B are moved along the printed conductive trace in order to completely measure the electrical properties of the entire printed conductive trace. This technique can also be used to overprint a conductive trace until a desired trace resistance is measured using electrical test unit 760. Overprinting may be required for printed conductive traces that are expected to carry a large current during the PWB intended operation.
In an embodiment of the ink printing mechanism 120, the process for printing conductive traces using thermal and piezoelectric technologies results in a droplet of conductive ink being ejected from an electronically-controlled printing element. In both cases, the printing element does not need to be in contact with the surface of the substrate and has a spacing that is typically between 1-2 mm. This spacing allows the test probes to be located at a closer distance to the substrate which then can be lowered to make contact with the printed conductive ink for continuity testing. Referring to
Referring to
The LTM 150 controls the position any of the ink printing mechanism, 120 or 120-1, in the vertical direction to provide an appropriate spacing required for printing onto substrate 105. Then conductive ink printing mechanism 120 ejects ink droplet 775 onto the substrate 105. The process continues as the head mount, either the dual function head 115-8 or the print-test head mount 115-7, is moved across the substrate 105 until a series of contiguous droplets create conductive trace 773. Testing the electrical performance is achieved with the probes holder mechanism 762 in the dual function head module 115e or the print-test head 120-1.
Reprinting a conductive trace results in printing over the original trace with the same or similar geometry. LTM 150 may automatically reprint the conductive trace if the measured resistance is above an operator-entered or calculated value. The calculated value for trace resistance can be automatically determined by LTM 150 knowing the printed trace geometry and the sheet resistivity of the printed conductive ink. When the apparatus 100 is configured for automated testing and correction it may carry either the dual function head 115-8 or the print-test head 115-7. This allows printing and testing to be done without reconfiguring the function head. Alternatively, the apparatus 100 may effect printing the conductive traces using the function head 115-1 (shown in
Various configurations have been depicted in this description and accompanying drawing for carrying and mounting a printhead, syringe dispenser, extruder, measurement device, and combinations thereof to a head mount 110. These configurations are to be considered examples and are not intended to limit the scope of this disclosure or appended claims. Other configurations for mounting devices effecting any of the functionalities disclosed herein may be adapted to the actualization of apparatus 100 and processes described herein. In the following processes wherein the apparatus 100 alternates between printing conductive traces and effecting measurement of the trace it will be accepted that any of the above noted configurations for effecting the functions of printing and measuring may be employed. For purposes of clarity, discussion of effecting exchanges of the printing function head module 115a for the measurement function head module 115e will be omitted and statement of the effected function is presumed to include such exchange if required by the configuration of the apparatus 100.
Processes are next described wherein the apparatus effects printing conductive traces and correcting flawed traces. The processes shown starts after a substrate 105 is loaded onto the table 104 or is formed on the table 104 by the apparatus 100 printing the substrate using nonconductive material or extruding nonconductive material to form a substrate. In these processes it is assumed that the probe separation d does not always permit and entire conductive trace to be tested in one measurement. However, it is possible that the probe holder mechanism 762 is adjustable with sufficient range for testing entire conductors. This depends on the PWB size and the range of the probe holder mechanism. Hence, it is understood that given sufficient range, operations to test entire conductors need only adjust the probe separation d to accommodate endpoints of the conductor. Thus it is implicit in the processes describe that if such range is available, each measurement operation constitutes adjusting the range and testing the entire conductor. Subsequent operations directed to testing the entire conductor in segments, or portions, are therefore obviated.
Referring to
When operation 814 yields a positive result flow proceeds to operation 816 wherein it is determined whether further conductive traces exist in the trace list to be printed. An affirmative result directs flow back to operation 804 and the next conductive trace is printed. A negative result ends the sub-process with all the traces described in the trace list having been printed, tested, and corrected if necessary.
Referring to
Once the printing data is prepared flow proceeds to the conductor printing and correction process 800 detailed above. As discussed this operation prints and test conductors as they are printed. A conductor is printed, then tested, and corrected if necessary. Each conductor of the list of conductive traces is thus printed and verified by measurement. After completion, flow proceeds to operation 844 wherein it is determined if nonconductive areas are to be printed next and operation 848 is effected to print the nonconductive areas if necessary. Alternatively, flow proceeds to operation 848 wherein it determined if there is another conductor layer or conductors in a further list to be printed. It is possible that a list does not comprise a complete layer, as portions of layers may be printed as a group. If further printing is required flow proceeds back to operation 842 wherein a next list of conductors is prepared for printing. If operation 848 yields a negative result, then all the conductive and nonconductive areas have been printed and the PWB is now ready to accept populating with components.
Referring to
When all printed traces of the layer or group are tested, operation 864 directs flow to operation 868 wherein a determination is made as to whether there are failed conductive traces. As positive result directs flow to operation 870 wherein the apparatus proceeds to reprint the failed conductive traces. Where the conductive traces are tested in segments, reprinting may be limited to reprinting only the failed segments. Once the reprinting is complete flow proceeds back to operation 854 wherein testing is again conducted. If no failures have been detected the sub-process is complete, all conductors of the group or layer have been successfully printed, and flow returns to a process calling the sub-process.
Referring to
After all conductors of a layer or group from the list have been successfully printed, flow proceeds to operation 882 wherein it is determined whether there are nonconductive areas to be printed after the last group or layer of conductive traces has been printed. If there are flow proceeds to operation 884 wherein the apparatus 100 prints the nonconductive areas as required by the processed PWB data. When no nonconductive areas are to be printed, or all nonconductive areas are printed, flow proceeds to operation 886 wherein it is determined whether there are further conductor layers or groups to be printed, and if so flow proceeds back to operation 842 and a next list is prepared to be operated upon by the conductor layer printing and correction process 850.
Printing conductive and non-conductive inks on a flexible substrate provides a means for positioning the final PCB assembly into a non-planar configuration. Over-flexing the substrate can cause damage to the printed conductive lines, printed non-conductive lines, electrical circuit components and a component attachment point to the printed conductive lines. Traditional methods for providing localized stiffness to a flexible substrate include a separate process of bonding rigid materials, such as glass/epoxy board or polyimide film, to one side on the PWB substrate. For this disclosure, the process for creating localized rigidity involves printing conductive and/or non-conductive materials during the fabrication of the PWB.
At locations where substrate flexing would cause damage to the PWB and associated epoxy and/or solder connections, printing a non-conducting material, such as non-conductive ink or thermoplastic, would increase the rigidity of the flexible substrate and prevent potential damage. For example,
A multitude of parameters are involved in printing a PWB. The parameters affect the quality of the PWB printed. In order to maximize the quality of a printed PWB controlling the parameters is desirable. Measuring environmental parameters before and/or during the printing and curing of conductive and non-conductive materials is useful to determining how the environment affects the manufacturing process and how environmental factors interact with the conductive and/or nonconductive materials before, during, and/or after the printing process. Additionally, differing printed materials have different characteristics which dictate printing parameters best suited for the given material. Furthermore, PWB designs have varying specifications and targets which also impact printing parameters best suited to the PWB. An embodiment of the present invention is directed to controlling at least some of the parameters affecting quality and also automating the control of at least some of the parameters.
The apparatus 100 is optionally equipped to measure printed quality of conductive materials and optimize the print quality of conductive and non-conductive materials based on one or more environmental factors. Referring to
The humidity sensor 118h is optionally attached to any of the positioner 90, the electrical measurement unit 760, or any convenient location on, in or near the apparatus 100 in order to measure humidity levels surrounding the PWB. In some applications, the apparatus 100 is placed inside a closed chamber and in this case, the humidity sensor 118h is placed inside the closed chamber in order to measure the humidity levels surrounding the PWB.
Referring to
Further optionally provided to the controller 95 is a print parameter adjustment module (PPAM) 935m which is software or firmware implementing an operator printing parameter adjustment interface and adjustments to be made to printing parameters used to print a PWB. For simplicity, the term “PWB” will be used to refer to printing either a circuit on a pre-existing board, or printing both a substrate (board for supporting printed conductive traces) and a circuit on the substrate. The PPAM 935m effects processes taking data from one or more of the temperature sensor 118t, humidity sensor 118h, and/or the pressure sensor 118p, and data representing a configuration and or environment of the apparatus 100, and further referencing “parameter set” data from the PPD 935d and parameters included in PWB file data or operator inputted data to provide prediction of performance of printed features and optionally optimization and implementation printing parameters for printing of a PWB. In the following discussion the term “prediction” means predicting a performance of a “printed feature” (i.e., conductive trace, insulator, substrate or other items previously discussed that are printed using apparatus 100) built using a given parameter set for the printed feature. The term “optimization” means finding parameters based on processing of stored data points and selecting and processing parameters of the store data points to achieve a desired result as is dictated by design parameters. The term “data point” refers to a set of some or all parameters and measured results that are stored in the PPD 935d and associated with a given printed feature (conductive trace, insulative layer, or other printed structure) or material. The term “parameter set” is used herein to refer to the following parameters categories: fabrication slice parameters; environmental conditions parameters; material quality parameters and design target parameters. These parameters are described below and shown in a “Parameter Set” of
The PPD 935d and the PPAM 935m are shown included in the controller 95, however it is to be understood that one or both of the PPAM 935m and PPD 935d are optionally implemented outside the controller 95 by another computer and optionally another storage device interconnected to the controller 95 directly or by any means of data communication including one or more of, but not limited to, wireless communication, a local network, or a wide area network (WAN) which may or may not include the internet. In such a configuration calculated printing parameters are sent to the controller 95 for use in printing a PWB. Operation of PPAM 935m, in conjunction with the PPD 935d, is discussed below.
Referring to
The ink-printing-mechanism (conductive) 120 and the insulator-printing mechanism 120′ are inkjet print heads which may be supplied with either conductive or nonconductive inks held in an ink reservoir which supplies a print head. Integrated printing mechanism have the print head integrated with the reservoir as a single unit. Referring to
An ink management system has the reservoir and the print head separate but functionally connected. In other words, the reservoir may be interchanged in the ink management system configuration. Referring to
The propellent device in the above configurations is optionally a thermoelectric print head (nozzles use heat to eject ink) 949-0 or a piezoelectric print head (nozzles have a piezoelectric element that changes size when voltage is applied to push ink out) 949-10. For reference and not limitation, the inkjet systems typically are used for materials having viscosities under around 20 centipoids (cps), but optional configurations may be used for materials having viscosities in the range of about 100-1000 cps.
The epoxy-printing mechanism 130 (epoxy is a non-limiting example) is not limited to epoxy but may generally be used for printing materials with viscosities not suited for inkjet print heads. Henceforth, to better convey the subject matter the term “extruder” is used in place of epoxy-printing mechanism. It is to be understood that extruder configurations related herein may be used apply, for example and not limitation, any of epoxy, conductive ink or other conductive material, nonconductive ink or other nonconductive material, or solder paste. Referring to
The extruders, 949-20 and 949-21, each comprises a plunger (not shown) that applies pressure to the material in the extruder reservoir 949-26 using the actuator 949-22 to extrude material onto the PWB. The extruders, 949-20 and 949-21, are designed to easily swap materials. In the pressure sense extruder 949-20, the plunger pressure sensor 958-24 is incorporated therein to measure the pressure being applied to the material to thereby providing pressure feedback. Monitoring the pressure over time provides means to determined material flow rate and amount. Optionally provided is the travel sense extruder 949-22 configuration without pressure feedback which instead measures advancement or retraction of a the plunger using the plunger travel sensor. The travel distance over time provides a mean to determine flow rate and amount. The extruders, 949-20 and 949-21, are used for materials with viscosities up to about 1000000 cps (1000 Kcps or 1 Mcps).
All print heads and extruders clog and the varying types have attributes suited for different applications. The thermoelectric print heads 949-0 are less expensive and easy to replace, but are not suited for as wide a range of materials as the piezoelectric print heads 949-10. The piezoelectric print heads 949-10 are expensive but are suited for a wider range of materials. Integrated inkjet printheads, 948-0 and 948-2, are easier to use for small prints, less expensive, and less complicated than the ink management system configurations 948-4 and 948-6. The ink management systems, 948-4 and 948-6, are better for huge prints or lots of printing but are more expensive and complicated than the integrated inkjet print heads 948-0 and 948-2. As used herein the term “print head,” unless further specified, for purposes of simplicity in this description is intended to generically refer to any of the printing mechanisms shown
Depending on whether a thermoelectric or a piezoelectric printing mechanism employed, different parameters apply. Each type has a “firing waveform”—the electrical signal (voltage vs time) that is used to push one or more droplets of ink out of a single nozzle. The parameters are presented below as examples and not limitations. These parameters are measured and/or controlled during the printing operation and are also optionally stored in the PPD 935d in correlation with other printing parameters for use as future references when adjusting the printing parameters.
For the thermoelectric print head 949-0 a “firing waveform,” is typically defined by a firing voltage (˜8-15V) and a firing pulse duration (nano to micro seconds). The material operating temperature while in the print head is in a rage of about ˜30-70 C. This temperature is measured by the temperature sensor 949-2 in the silicon of the print head and can be controlled by either: (a) the heater 949-4 which is embedded in the silicon or (b) firing the thermoelectric nozzles 949-8 or (c) running current through firing elements of the thermoelectric nozzles 949-8 such that they heat up but do not fire. There is a minimum temperature because some materials might not jet below the minimum, and there is a maximum because heat from firing the nozzles leaks into the material and some materials will breakdown above a certain temperature.
For the piezoelectric print head 949-10, a firing waveform is typically more complicated than that of the thermoelectric print head 949-0 and can have several pulses at different durations and voltages and can produce multiple drops as a result. For example and not limitation, a waveform with 2 pulses might produce a single 8 pL drop, but a waveform with 3 pulses might produce an 8 pL drop and a 4 pL drop that combine to produce an effective 12 pL drop. The material operating temperature is typically in a range of about 30 to 90 C and is measure by a temperature sensor 949-2 at the print head 949-10. The temperature is not influenced too much by the piezoelectric print head 949-10 and is more controlled by the heater 949-4 disposed external at the reservoir 949-6 along with the temperature sensor 949-2 sensor which monitors and controls the material temperature at the reservoir 949-6.
For the pressure sense extruder 949-20 a “working pressure” provides pressure feedback which is a pressure measurement parameter used for controlling material distribution. For the travel sense extruder 949-21 a “pre-extrusion amount” and a “retraction amount” is optionally used as a parameter instead of working pressure using the plunger travel sensor 958-25 to senses a travel distance of the plunger and thus displacement. Another parameter for the syringe extrusion head is “Flow Speed,” which is how fast material is flowing out of the head when it is flowing. The flow speed is inferred from either pressure feedback sensing or the plunger travel distance and a time period.
A starting point for fabricating a PWB using apparatus 100 is a PWB CAD file. A designer uses a CAD tool to design a PCB (printed circuit board) which produces the PWB CAD. As discussed previously, various CAD tools exist. For the sake of simplicity, a GERBER format file is referred to in this specification but this is not a limitation as the present invention may be adapted to other formats using methods known to those skilled in the art. The printed circuit board is composed of one or more “layers” of conductive traces. CAD tools currently only deal with the conductive layers and use drill files to specify interconnects between layers. These will be referred to herein as “CAD Layers” and “Drill Files.” As explained previously, the layout translation module 152 imports the “CAD Layers” and “Drill Files” to create a series of “Fabrication Layers.”
In order to best convey the process involved, a hypothetical PWB example is next described. Each of the fabrication layers contains all the information about conductive, insulating and/or other material needed to build that layer. For a typical “4-layer board” (what a traditional PCB manufacturer would call a 4-layer board) there are the following files:
The layout translation module 152 imports all of those files and converts them into 4 or more “fabrication layers”, shown below chronologically in build order but physically upside down:
Each “fabrication layer” is divided into one or more “fabrication slices.” A “fabrication slice” is the design information needed to build something with a specific material, e.g., inter alia, conductive ink, nonconductive ink, or epoxy. Continuing with the previous example of the “4 layer board,” the following fabrication slices are produced:
The PPD 935d stores numerous parameters and the PPAM 935m performs processes utilizing the stored parameters and parameters measured in process. These parameters are collectively referred to as “the parameter set.” Referring to
1. Fabrication Slice Parameters;
2. Environmental Condition Parameters;
3. Material Quality Parameters; and
4. Design Target Parameters.
In an embodiment the apparatus 100 including the PPAM 935m and PPD 935d, the PPAM 935m optionally adjusts one or more fabrication slice parameters, optionally measures one or more of the environmental condition parameters, optionally reads or receives one or more material quality parameters, and performs adjustments to meet the design target parameters.
Each fabrication slice has a fabrication slice parameter set comprised of 2 categories of parameters: (1) material and hardware parameters; and 2) process parameters. For a given slice, the fabrication slice parameter set is comprised of the following:
“Environmental Condition Parameters” are parameters which define the conditions of the surroundings of the apparatus 100 and comprise the following:
The material quality parameters characterize the individual materials printed by the apparatus 100 to fabricate the PWB and comprise:
Still further design parameters are used in the fabrication of a PWB and comprise what are optionally termed the “Design Targets” or “Design Specification” or “Design Tolerances” and vary depending on the layer and/or type of material being printed and the printed feature to be printed. Examples of these parameters are shown below in relation to the material involved.
While a given collection of parameters comprising the parameter set is detailed above, it is to be understood by those skilled in that the present invention does not require that each of the above parameters be included in processes detailed herein. Likewise, the above collection of parameters is not to be considered closed ended, as the present invention optionally includes further parameters characterizing any one or more of fabrication parameters, environmental conditions, material qualities, or design parameters. As used herein the term “nonconductive material,” unless further contextually qualified, will be used to refer insulating materials whether configured as an ink, epoxy or other hardening substance. For purposes of simplicity herein, the term “printing material,” unless further contextually qualified, will be used to refer to any of conductive or resistive material, insulating or nonconductive material. For purposes of simplicity herein, the term “conductive material,” unless contextually qualified, will be used to refer to any of conductive or resistive material wherein “resistive material” is intended to refer to materials having a resistivity suited for printing resistive features.
Testing procedures are used to determine various material and hardware parameters. In an embodiment of the invention the testing procedures include printing a test swath of printing material and determining its quality. The test swath is created by firing all nozzles of a print head in rapid succession to create a printed “block.” In the following description the term “material agnostic” is used to mean that a process applies to any material and the term “material specific” is used to mean that the process is directed to measurements, observations, and qualities that are specific to the material being tested.
A test swath is printed to preferably have the following material agnostic characteristics;
Minimum and maximum operating temperature parameters (material agnostic) are typically supplied by a material manufacturer. However, these parameters may be determined by testing preferably using best nozzle firing voltage and timing for the material. The temperature on the print head is measured and test swaths are printed using increasing temperature until the material under test begins to be deposited. This is the minimum temperature. Temperature is continued to be increased until material is no longer being deposited and that temperature is the maximum temperature.
Substrate operating temperature (material agnostic) is determined by printing swathes at different temperatures and evaluating the swaths. If the material is “beading up” (forming small droplets) then the temperature should increase (or you put down less material).
A distance between drops (material agnostic) is evaluated by printing swaths at different temperatures and varying the drop distance at each of the temperatures. The swaths at each temperature are evaluated to see if the material is “beading up” (forming small droplets). If this occurs then the distance should be increased. If there are visible gaps between the material then the distance should decrease.
A UV curing profile (material specific) is usually supplied by the material manufacturer. When it is not test swaths are printed using optimal parameters determined as discussed above. For nonconductive ink, i.e., dielectric (insulating) ink, the test swaths are printed using sets of test curing profiles and are examined for a smooth, consistent result. There should not be ridges on top (minor ridges are ok, deep trenches are not), the material should not be wet when touched, and a specific thickness is achieved.
The final thermal curing profile (material specific) which may not be manufacturer supplied, is determined by using a set of test final thermal curing profiles on test swaths which preferably produced using an optimal intermediate curing profile. For conductive ink resistance is measured as heating is increased. The measured resistance should decrease slowly and then reach a point, an optimal final curing profile, where there is no significant gain by further heating. The material should not be wet when touched (if so, it needs more heat or more time). The material should not crack when curing (if so, it needs less heat or more time at a lower temperature).
An intermediate curing profile (material specific) is generally not be supplied by the material manufacturer. As layers of ink are stacked, improper cures on a lower layer cause issues inside the board. For conductive inks, multiple layers are printed with multiple types of ink stacked on top of each other. A set of intermediate test profiles are used. Testing begins a high temperature and short time. If the layers crack and/or bubble the temperature is reduced and time increased until layers stop cracking/bubbling and the material reaches appropriate levels of conductivity.
The term “pass” used herein refers to one pass of a print head applying a material. Multiple passes of the print head may be required to achieve acceptable results. An optimal number of passes (material specific) for conductive ink is determined by measuring the resistance of a specific trace, and if too low increase the number of passes until it does not improve significantly.
For determining an optimal number of passes for insulating ink, the configuration of insulating ink printed (i.e., printed by varying test number of passes) is sandwiched between printings of conductive ink. A bottom conductive trace is first printed followed printing test numbers of passes of insulating ink and a final printing of a top conductive trace on top of the printed pass(es) of insulating ink. Resistance between the top and bottom conductive traces is then measure. If the resistance is too low, the number passes is increased to an optimal number whereat a sufficient level of insulation is achieved and increasing the number of passes produces no necessary improvement.
It is to be further understood that the above procedure is optionally used to measure a dielectric constant of the insulative material. The electrical measurement unit 760 is optionally equipped to apply signals testing a resultant capacitance of the test structure printed above and calculate a dielectric constant based on a measured capacitance and physical dimensions of the test structure. Various insulative materials may be chosen based on their dielectric constant.
A description of tests used to obtain parameters of materials used in the fabrication of a PWB is provided above. The tests use the best parameters so far determined for a material to run subsequent test. The above described tests can be run iteratively and (technically) in any order. A preferable order is presented above. However, one skilled in the art may vary the order after obtaining an adequate initial set of parameters.
In a further embodiment of the present invention the above test processes are automatically performed by the apparatus using processes optionally incorporated into the PPAM 936 along with operator input regarding evaluation characteristics not automatically obtainable. For example, the operator may need to input data such as material type, lot number, etc. if it is not automatically available. The machine stores the parameters. Automation of the tests permits timely incorporation of parameters for new materials. The environmental conditions used default to “standard office environment conditions.” For the purposes of this disclosure the “Standard Office Environment” is taken to be: Temperature: 18-23 C; Relative Humidity: 30-50%; Pressure: 1013.25 milliBar (plus or minus 10 milliBar); Lighting: 300-500 lux (from an artificial light source). Alternatively, the apparatus stores specific environmental parameters such as temperature, pressure and/or humidity using available sensors. Alternatively, the operator may enter the environmental parameters.
For performance prediction, specific test circuits are fabricated and measured by the machine. The resulting measurements are stored in a flexible but detailed format so they can be applied to other things. For each “conductive fabrication slice” there is a set of conductive traces. Each conductive trace is broken into conductive segments for measurement. Each of those segments is measured and the result is stored. This produces a large collection of data points. Each data point has a measured width, measured resistance, specified x,y coordinate and is stored in three of the four parameter groups (Fabrication Slice Parameters, Environmental Conditions, Material Quality; which is everything except the Design Targets). The the system uses the data to predict performance based on the past data.
The tests presented above are for storing parameters for characterizing various materials used in the fabrication of a PWB. The stored parameters are used to optimize parameters used in the fabrication of a PWB using specific materials of the materials characterized. In summary, the above characterization tests accomplish the following:
The PPAM 935m effects an optional operator selected function that optimizes printing parameters when printing a PWB with a known material that has been characterized by the tests described above. For example, the temperature sensor 118t and the humidity sensor 118h provide data to the PPAM 935m which determines that the printing parameter values permit proper curing of the conductive and/or non-conductive printed materials. It is known in the industry that when printing conductive materials, such as silver nano-particle inks, cure temperatures below 120° C. often result in poor electrical conductivity.
In multilayer printing applications requiring the printing of conductive and non-conductive materials, cure temperatures over 120° C. can cause warping or other deformation of the PWB. In this case, lowering the temperature during the sintering process for a conductive trace will improve the flatness of the multilayer board with an associated decrease in the electrical conductivity of the conductive traces. Moderating the temperature through the cure process has a huge impact on an overall performance of a multilayer build.
Referring to
Optimizing Print Quality with Material and Hardware Aging.
Conductive and non-conductive materials degrade with age. Typically, these materials are given a shelf life specification as a benchmark for the operator to know when the materials need to be replaced. Often the specified shelf life is assuming that the material was properly stored, for example, in a refrigerated environment. If the material is not properly stored, the shelf life will be decreased but absent actual use there is no way of knowing if the material is still useable in printed PWB.
In a further embodiment of the apparatus 100, configurations utilizing the PPAM 935m are optionally provided to ascertain the age of the conductive material and/or the nonconductive material that is being used. In one configuration a manufacture date and optionally other meta-data is stored inside a memory chip on or within a print cartridge. This allows the apparatus to read the date automatically without operator intervention. An interface between the chip and the apparatus may be implemented by any of direct electrical contact, or wirelessly via Bluetooth, optical means such as an IR interface, or an RFID.
In another configuration wherein a cartridge does not have a memory chip, there is provided a QR code, a barcode, text, or another optically scannable message on the cartridge. Referring to
There are situations where a cartridge is not provided with a means of indicating its manufacture date or age since manufacture. Thus, in still another optional configuration, the apparatus is configured to accept manual entry of one or more indicia including but not limited to a manufacture date, lot number, product code, or other indicia permitting access to data containing an indication of a manufacture date. Where the manufacture date is not directly provided, the PPAM 935m is optionally configured to access a manufacturer's database either through a local network or a wide area network including the internet whereby a manufacture date may be access via use of any of the aforesaid indicia on the cartridge.
Still further, there exists the situation where a cartridge manufacture date is unknown and means are not provided with the cartridge to ascertain the manufacture date. For such a situation in the case of the cartridge containing conductive ink, the PPAM 935m is configured to conduct measurement of a printed test trace to provide information on an expected shelf life under current conditions. In one embodiment, the apparatus 100 provided with the electrical measurement unit 760 and the PPAM 935m, prints a test trace on a test trace coupon and measures the characteristics of a printed test coupon. The PPAM 935m then compares measured print characteristic to characteristics for a like material stored in the PPD 935d and determines an estimate of the manufacture date and/or remaining lifetime of the material. The apparatus 100 then displays the estimated manufacture date and/or an indication of the quality of the material before proceeding with a PWB fabrication.
In another embodiment, the PPAM 935m operates the electrical measurement unit 760 to record over time a measured performance, such as resistance or conductance, of an installed conductive material being used to produce a set of PWBs and creates, in the PPD 118d, an installed material history database (IMHD) containing electrical performance over time data for the installed material. Optionally, the dielectric constant of nonconductive material is also tested as described further herein. Test are optionally periodically made of nonconductive material over the material life span to store data indicating its aging behavior. The PPAM 935m then uses the IMHD to estimate the remaining lifetime of the installed material and displays indicia indicating a remaining lifetime and/or quality of the installed material. In the embodiment of the apparatus 100 containing the PPAM 935m, the PPD 935d, and the electrical measurement unit 760, the IMHD is optionally automatically created without requiring operator intervention when testing PWB builds. If the conductive material in use is degraded to the point where continuing use is unacceptable, the PPAM 935m alerts the operator. This process permits significant time and cost savings in comparison to current systems where a processed PWB would be moved to a separate test system in order to check the quality of the PWB.
In a further embodiment, PPAM 935 uses the IMHD to automatically adjust the printing parameters to take into account the installed material's age and degradation level. If the material falls below a certain performance threshold the operator is presented with a warning where the operator can choose one of several options, including but not limited to, replacing the old installed material with new materials, initiating automatic adjustment of the printing parameters, or manually adjusting the print parameters to compensate for the degraded installed print materials.
For example, when apparatus 100 is configured with function head 115 having printing mechanisms 120 or 130 respectively containing an inkjet cartridge which releases conductive or non-conductive ink, ink droplets released will have an expected volume, or mass, of material that is deposited with each drop. There are several factors in the performance of the ink deposition that degrades over time. As stated above, the conductive or nonconductive ink inside a cartridge has a limited shelf life and the quality of the printed ink will decrease over time. Additionally, as inkjet cartridges and print heads age the amount of ink deposited may decrease over time. For example, a new thermoelectric print cartridge filled with new silver nanoparticle ink can output one gram of ink using approximately 20 million drops of ink. An older cartridge containing older ink will deposit less material per drop and it can take 35 million drops of ink to the achieve the one gram of ink. This degradation can be directly measured as weight, or indirectly, using apparatus 100 with electrical measurement unit 760, and the PPAM 935m taking a measurement of the resistance of a printed trace.
In one embodiment, the PPD 935d includes the IMHD having a database containing resistance measurements as a function of the age of the print cartridge and associated ink and the PPAM 935m optimizes print parameters in accordance with the database. For example, the PPAM 935m predicts the performance of a printed trace based on the calculations from the database. The PPAM 935m automatically adjust a number of print layers required to achieve a certain level of performance in the PWB. Alternatively, the PPAM 935m may also display a warning to the operator that the PWB performance may be degraded and allow the operator to continue the current printing process, adjust the number of printed layers or replace the print head and/or ink.
When printing non-conductive inks, photo-initiator-based or UV-curable inks can significantly degrade over time. Fresh UV-curable inks can reach a satisfactory level of solidification within seconds if they are fresh and handled properly. Old UV-curable inks can take up to 10 times longer to cure. In one embodiment, the PPD 118d includes the IMHD having a cure time database containing cure time as a function of the age of a print cartridge of nonconductive ink. The PPAM 935m periodically checks the age of the non-conductive ink and optimizes the curing parameters. Apparatus 100 can automatically adjust the curing time of the UV-curable inks required to achieve a certain level of performance in the PWB. Apparatus 100 may also display a warning to the operator that the PWB curing time will increase and allow the operator to either continue the current printing process, adjust the curing time or replace the print head and/or ink.
Several hardware components contained in apparatus 100 can also degrade over time and require periodic maintenance or replacement. For example, heater 118 for heat sensitive curing will slowly degrade until they can no longer reach temperatures high enough to cure the printed material. Temperature sensor 118t can used to sense the achievable heater temperature and adjust the power delivered to the heating element. Apparatus 100 can create a database of the measured temperature as a function of age of the heater 118t. The database may also include the required power to drive heater 118t. Apparatus 100 may also use the database to extrapolate the time to when the heater 118t will need to be replaced. Under a maintenance option, apparatus 100 can display the current state of the heater and may also include the expected lifetime of the heater 118t before replacement is needed.
Another component contained in apparatus 100 is the UV heater 118a required to cure the UV-curable inks UV heater 118a is typically a series of UV LEDs that activate the curing process of non-conductive inks UV heater 118a will also degrade over time resulting in a lower amount of UV energy being emitted from the element. Apparatus 100 can compensate for the reduction of emitted energy by increasing the amount of power delivered to the element. Apparatus 100 may use a database of the required power delivered to the UV heater 118a as a function of time to compensate for the age of the heater. Apparatus 100 may use the database to extrapolate the expected lifetime of UV heater 118a. Under a maintenance option, apparatus 100 can display the current state of the UV heater 118a and may also include the expected lifetime of the UV heater 118a before replacement is needed.
Apparatus 100 also contains a positioning system which includes x-axis motor 101a, y-axis motor 102b and z-axis motor 103c. The axis motors, and associated hardware, position the function head 115 and table 105 relative to one another for printing the PWB. The positioning system components degrade over time and quality of the printing calibration will also degrade. For example, a new calibrated positioning system will properly print a 200 um wide conductive trace, However, with age degradation the positioning system will begin to print that same trace to a width of 400 um. Apparatus 100 optionally uses a database of the printed line width degradation as a function of time to compensate for the expected increase in line width. Apparatus 100 optionally automatically adjusts the printed line width based on the database information or apparatus 100 may display that the line width will be outside a previously set threshold.
Referring to
In operation 950-4 the apparatus 100 displays a performance prediction display. Details of operation 950-4 are shown in further provided in the flowchart of
In another optional embodiment of the invention, operation is limited to prediction of design parameters without optimization of fabrication slice parameters. In that embodiment operation 950-4′ replaces operation 950-4 and is detailed in a flow chart of
Once the operator has completed the setup and configuration operation, including selecting one of automated optimization or manual adjustment of one or more of fabrication slice parameters, environmental condition parameters, or material quality parameters, the flow proceeds to a build and measure operation 950-6. During the operations the apparatus is optionally controlled by the PPAM 935m which runs via the PCM 128 a build of the PWB in accordance with the parameters either automatically or manually determined in the project setup and configuration operation 950-4 or 950-4′. The build and measure operation 950-6 is further detailed in the flowchart of
Upon completion of the build and measure operation 950-8 flow proceeds to a store results operation 950-10. In this operation the PPAM 935m takes the measurement results from the build and measure operation 950-6, and the parameters set in the project setup and configuration operation 950-4 and stores the parameters used and measurements taken in the PPD 935d for future reference as data points in PWB fabrications employing like materials and parameters.
In an embodiment of the present invention, the apparatus 100 is optionally set to a full automation mode wherein the operations described herein are automatically implemented without the need for operator intervention unless predicted design parameters do not satisfy design parameters uploaded or previously input by the operator. In such operation displays of parameter set data, including predicted design parameters and optimized design parameters, are optionally omitted. In other words, the PWB build and measure operation 950-6 is performed without the need for the operator to accept predicted design parameters and/or optimized parameters or initiate the build and measure operation 950-6 during the project setup and configuration operations of flow charts of
Referring to
In an embodiment of the present invention the PPAM 935m performs optimization of process parameters to provide a set of initial process parameters and an initial prediction of performance results. This process is shown in the flow chart of
Options are provided to the operator permitting examination of selected features of the CAD file. For example, the operator is able select other specific traces contained in the CAD file such as, for example and not limitation, one or more of matched traces, high conductance traces, or nonconductive features using the “SELECT TRACE” button. The PPAM 935m calculates the trace or feature characteristics, displays same, and presents the operator with options for adjusting printing parameters. As stated above the display shown in
Referring again to
When determining the initial performance prediction, the PPAM 935m automatically performs optimization and arrives at an initial set of operation parameters. This process is detailed in
Optimization further optionally includes minimizing production time while meeting the design parameters. Reducing production time is primarily controlled by the fabrication slice parameters, such as curing profiles and the number passes required to meet the design parameters. In minimizing production time data points the K nearest data points are ordered and selected based on minimizing production time.
When further automatic optimization is selected, the flow proceeds to operation 952-5 wherein the operator is given the option to modify at least one of filtering criteria to better correlate to the current build, build material selection (material quality parameters), or design parameters including but not limited to resistance values, and/or tolerances. The operator is also optionally allowed to modify design parameters which may have been overly stringent. The flow return to the operation 952-1 wherein optimization procedure is then run again with the modifications made by the operator held constant during the optimization.
The operator may select manual adjustment which proceeds with operator manually adjusting at least process parameters 952-6. This is done by further displays and the operator manually entering parameters. The flow return to the operation 952-1 wherein optimization procedure is then run again with the modifications made by the operator held constant during the optimization and the optimization being limited to providing predicted results with process parameters held constant. Alternatively, the operator may decide that the predicted results do not sufficiently meet requirements and that the build should be re-evaluated.
In an optional embodiment of the invention, the PPAM 935m is configured to only effect prediction of design parameters based on previously entered fabrication slice parameters, and environmental condition parameters and material quality parameters. In this embodiment the flow chart of
In the embodiment of the apparatus 100 wherein a fully automated mode is implemented, the decision presented in operation 953-2 is automated such that if the predicted design parameters meet requirements, flow automatically proceeds to the build and measure operation 950-6. If the requirements are not met, the operator is alerted, failed requirements are optionally displayed, and the operator can elect to effect adjustment or abort the build.
Parameter optimization for conductive traces is directed to minimizing resistance to meet a target parameter. The resistance formula for a traces is expressed as follows:
Resistance=effective_resistivity*length/(width*depth)
Length is controlled by the design parameter and other effects from various parts of the process are negligible. Width is controlled by the design parameter. At small scales (near the resolution limit of the print head) the width can be affected by the process parameters:
An embodiment of performance prediction is preferably done utilizing the statistics of subject matter, but an alternative is to use a single predicted value. Statistical distributions are refined for various scenarios. The primary parameter predicted is trace resistance. Trace resistance prediction uses the same equation used for optimization:
Resistance=effective_resistivity*length/(width*depth)
In practice, it is preferable that every printed segment is stored in the PPD 935d with all of the parameters that were used to build it and the resultant measured resistance. Every stored segment has an effective resistivity. In predicting resistances, a portion or all of the past measured conductive traces are used to predict the distribution of predicted resistance. A median of the distribution is the expected value for the prediction.
As the apparatus is used for many builds of PWB's, the PPD 935d grows to include a large number of data points, i.e., printed trace parameters and measured resistances. In an embodiment, the PPAM 935m further refines the prediction by filtering out unrelated samples. For example, without filtering all the conductive materials will be included in the prediction which is not ideal since most of the conductive materials will not be the same as the material being used in the build. Thus, filtering is used to remove samples made from materials from a different manufacturer or samples made from a different material.
A process is optionally used wherein filtering is based on material and age which permits evaluation of performance changes for a material over time. The process for example optionally includes, filtering first to obtain all data points for a given material type “X” from manufacturer “Y.” Then filtering is done for varying age ranges of the filtered results to determine performance changes of the material with time, for example effective resistivity or preferred curing profiles. Filtering is also optionally done for the given material “X” at a certain age while varying the filtering for the manufacture to evaluate how performance changes from one manufacturer to another.
An additional level of filtering is optionally done by looking at quantitative features and removing samples having a parameter beyond a certain amount. For example, only look at samples that have the same number of passes (plus or minus some percent). Or samples having a length that is within a given percentage of the design trace length or design resistance.
When performing an optimization, filtering for material quality is optionally effected. Data points for any material that is from a different manufacturer than being used in the current build are removed. Similarly, data points for any material that is a different product is removed. Typically, data points in the filtered results for materials of a different age or lot number are retained. However, if there is a sharp change in performance of the materials at specific ages then filtering will be done to group data points by age and keep only those groups within a desired range of the age of the material being used in the build. Similarly, filtering is optionally done if a particular lot number shows a very different performance than other lots. In that case, filtering is used to group data points by lot number and keep only those within the same lot number group.
In view of the above, the present invention provides filtering optionally performed at varying levels such that data points for “Product A” should not be used to predict how “Product B” will perform. Additionally, materials from different manufacturers are also distinct and do not predict how the others will perform. Still further, material (product) of a given lot number (or batch of material that this sample is part of) should perform similarly to the same material (product) of different lot numbers, but there may be slightly different results. If results are significantly different (beyond a pre-determined percentage), filtering based on lot number may be optionally implemented. The PPAM 935m is optionally configured to periodically filter based on the lot numbers to determine when such optionally filtering is to be effected.
The apparatus 100 is typically in a lab environment (i.e. “Standard office conditions”) which has relatively stable lighting, temperature, humidity, and pressure conditions so filtering on environmental conditions is optional. However, there are scenarios in which the apparatus 100 is used in different environments. For those scenarios conditions can vary a lot and filtering based on environmental conditions is invoked. This is optionally done automatically based on results from environmental sensors of the apparatus 100. In those scenarios, each of the environmental conditions are compared against performance (i.e. Temperature vs Effective Resistivity). If there is a significant change (an operator selectable predetermined amount) in performance (for example, a 50% increase in effective resistivity at temperatures below 20 C, but “regular” performance at temperatures above 20 C) then those threshold values are used to filter groups and the current environmental measurements are used to filter groups of data points to use for prediction. For example and not limitation, there would be a “<20 C” filtered group and a “>=20 C” filtered group; if the current temperature is 25 C then the “>=20 C” filtered group is used in the prediction and the other groups are ignored.
Most fabrication slice parameters are handled like the environmental conditions; they are compared against performance and any location where there is a significant change in performance is used as a group threshold. Things in the same group as the current setup are used in the prediction.
In an embodiment of the present invention, a prediction model is used wherein it is optionally targeted to have around 100 data points from the stored parameter set. The number of targeted data points may be varied within the scope of the present invention. If there are more than 100 data points, the data is filtered so that it includes more relevant data. Filtering is preferably done in the following order: Material Quality first, Environmental Conditions second, and Fabrication Slice Parameters last. This order may also be varied within the scope of the invention. If the filtering process produces a number of data points that falls too low then the filtering process is set less strict. Once the data points are filtered, the resultant filtered data points are used to compute a performance criteria of a given feature. For example, an average resistance as a function of trace segment width and trace segment length.
The processing to predict characteristics includes about 20 parameters. All of the data points are put in a N dimensional space (20 dimensional space). To predict a performance point the point is put into the N-dimensional space and nearest K data points, hence neighbors, are found. As used herein “data points” refer to data sets in general, and “neighbor” is used to refer to data points having a relative location to a reference point. A median or mean is then found for the nearest K neighbors to compute a predicted value.
Finding neighbors in an N-dimensional space is a process known to those skilled in the art. In the interest of an understanding of the present disclosure, a non-limiting simplified hypothetical explanation is presented. Every point on a two-dimensional map can be represented as a pair of numbers: an x,y coordinate. The x value represents the distance of the point from the origin horizontally. The y value represents the distance of the point from the origin vertically. To compute the distance between point A (at xa, ya) and point B at (xb, yb) we use: distance=sqrt((xa−xb)**2+(ya−yb)**2) [NOTE: ( )*2 means “to square” or multiply the thing by itself, i.e. x**2 x*x; sqrt means to take the square root]. If we move from a 2-dimensional map to a 3-dimensional space with x, y,z coordinates then the distance formula becomes: distance=sqrt((xa−xb)**2+(ya−yb)**2+(za−ab)**2). When dealing with multidimensional space this extends to an arbitrary number of dimensions. So to compute the distance from a point in N-dimensional space to another point in N-dimensional space we first compute the difference between the selected point and the other point in each dimension, then square that number, then add all the squared numbers, then take the square root of the sum.
In the embodiment of the present invention discussed herein there are several values which have specific numeric values but there are also some values that do not. For non-numeric values we must convert them to a number or remove them from the analysis. The filtering operations previously mentioned help with this by providing evaluations which can be given a number. After we have a data set with only numeric values we then “normalize” the numbers so that they are all between 0 and 1. For each dimension: find the minimum and maximum values along that dimension; then divide each number by that range. This helps ensure that everything is considered equally. Once normalized the data points are ready to be searched.
The PPAM 935m searches for the K-nearest neighbors around a current data set of input parameters ((Fabrication Slice Parameters, Environmental Conditions, Material Quality), basically what is near the operating point that the operator has selected. The cleaned and normalized saved data (as described in the previous paragraph) is used and a distance from the current data set operating point to every other point in that set is computed. This will result in a list of {distance, data point} pairs. That list is then sorted by distance so the smallest distance is first. Then the first K elements of that list are taken as the K nearest neighbors.
The above example is simplified and non-limiting as those skilled in the art of statistics/software/machine learning will realize there are more optimized ways to perform the computation. Therefore, it is to be understood that such optimizations are considered to be within the scope of the present invention.
Predicting the performance of the printed PWB based on environmental factors allows an operator to chose for either open or closed loop fabrication. Apparatus 100 optionally provides the operator with the option to automatically optimize the print parameters across the complete board or select the option to only adjust certain printed traces for higher or lower electrical performance. This option is provided via the “ADVANCED OPTIONS” button shown in
Referring to
PWB Parameter Prediction and/or Optimization.
Referring to
The concept of “layer” is a result of the translation of traditional PCB CAD files which are organized in layers. The LTM 152 converts these files to “slices” as related above. Hence, when printing a PWB the apparatus 100 operates on a slice basis and the “layer” terminology is vestigial from the traditional PCB CAD files. However, it is retained here for purposes of reference. Thus, a number of slices per layer may optionally be used in the processing, and the slices are organized according to a PCB CAD layer they were derived from. Optionally, reference to layers may be omitted and slices merely arranged in continuous order from bottom up.
In operation 958-3 layer parameter processing begins and a number of layers present in the parameter set is stored. Operation 958-4 begins slice parameter processing and a number of slices in the instant layer is stored. Operation 958-6 performs filtering on the data points for slice parameters. As noted previously, the slice is a term given to printing a single material to produce items represented in the slice. Hence, all printing done for a slice with be one of conductive material, nonconductive material, or resistive material. Thus, filtering at this stage is based on the selected material. Operation 958-8 begins item processing for producing individual items of the slice, with the number of items of the slice being stored. Breaking down processing to include item level processing is optional. Since a given slice is produced using a single material, processing parameter selection for use across all items of the slice may be sufficient. However, a greater level of prediction and/or optimization may be achieved by processing item by item because significant differences may exist in the design parameters between items in a single slice. For example, high conductance traces may exist for power handling along side traces carrying signal which do not require high conductance. In the interest of more selective processing for more directed results, filtering is optionally conducted on an item by item basis in operation 958-10 using the design parameters of the items.
In operation 958-12 it is determined whether data point models exist for the item. As a result of the filtering in operation 958-10 and an unusual item design parameters no data points may exist. In such case a default set of parameters is applied in operation 958-18. However, once it is verified that sufficient data points exist, the K nearest data points in the previously described multi-dimensional space are found in operation 958-14. If fewer than K data points exist, optionally the operator is prompted to reduce the number K and the actual number of available data points may be shown.
Optionally provided is a selection of a mode of operation. Operation 958-13 examines whether optimization or prediction is the selected mode of operation. If optimization is the selection then flow proceeds to operation 958-16p wherein process parameters are optimized. Alternatively, if prediction is the selected mode, then flow proceeds to operation 958-16d wherein resultant design parameters (one or more of conductance, resistance, dielectric constant, mechanical strength, or nominal resistance) are predicted based on existing fabrication slice parameters, environmental condition parameters and material quality parameters and test results stored in the PPD 935d.
In operation 958-16p either a mean or median is taken of process parameters of the K nearest data points and used as optimized process parameters for the item. Hence the process parameters for the item are optimized because the data points used for the process parameters are also those that are the nearest neighbors of the data point of the desired design parameters. Using the K nearest data points, predicted design parameters are determined by taking the mean or median of the stored design parameters of the K nearest data point which have been found from actual measurements previously discussed. Optionally, optimization may extend further to other parameters of the parameter set that maybe modified such as the aforementioned hidden parameters.
It will be understood that the above optimization procedure is optionally modified to a purely prediction procedure in the case of manually entered parameters in operation 952-6 of
Processing continues to operation 958-20 where it is determined if all items of the slice have been optimized and if not the item count is incremented in operation 958-21 and flow proceeds back to operation 958-8. If all items of the slice are optimized, or have predicted design parameters calculated, flow proceeds to operation 958-22 wherein it is determined if all slices of the layer have been operated on and if not the slice count is incremented in operation 958-24 and flow proceeds back to operation 958-4. If all slices of the layer are operated on flow proceeds to operation 958-26 wherein it is determined if all layers of the PWB build have been operated on and if not the layer count is incremented in operation 958-28 and flow proceeds back to operation 958-3. Once all layers are operated on the PWB optimization or design parameter prediction is complete.
Referring to
In operation 960-6 the PCM 128 prints the items of the given slice in accordance with the parameter sets of the respective items which also includes effecting the intermediate and final curing profiles. As noted previously, optionally a parameter set may apply to an entire slices with all items of the slice being printed using the parameter set of the slice. Following curing, in operation 960-8 the apparatus 100 operates using the electrical measurement unit 760 to measure items printed and store measurement results along with the associated parameter set in the PPD 935d. In operation 960-10 the measurement results are compared with the design parameters and variation from design parameters are examined in operation 960-12. If the measured results do not meet the design parameters the operator is optionally notified and a repair process is initiated, with or without operator intervention, wherein operation proceeds to the decision operation 960-14.
A repair count is kept and incremented each time a repair process for an item is initiated. The apparatus is optionally equipped with optical interface device 118o which scans the PWB build to determine if the build is repairable. Known video processing procedures are used to determine if certain criteria are met, such as, for example and not limitation, warping or other deformation, or printing inconsistent with normal operation. If operation 960-14 determines the criteria are met the build is aborted and flow proceeds to operation 960-20 wherein the operator is notified. In an embodiment the operator is optionally given the opportunity to remedy the situation and initiate the repair process of operations 960-16 and 960-18 or proceed to operation 960-24 whereby another slice build is initiated.
In operation 960-14 it is examined whether the repair count has exceeded a predetermined maximum value and if so flow proceeds again to operation 960-20. If the maximum value is not exceeded flow proceeds to operation 960-16 and the repair count is incremented and flow proceeds to operation 960-18 wherein a repair is initiated. Following completion of the operation 960-18 flow proceeds to operation 960-8 wherein measurements are again taken to verify effectiveness of the repair.
In operation 960-18 parameters of the slice is reduced to include only parameters of failed traces. The repair process 960-18 then, optionally, comprises one of the following alternative embodiments:
Operation 960-12 verifies that measurement result meets design parameter requirements, and the results are optionally stored as a data point in the PPD 935d. Flow proceeds to operation 960-22 wherein a slice count is examined to determine if all slices have been built. If slices remain to be built flow proceeds to operation 960-24 wherein the slice count is incremented and flow returns to operation 960-4. If all slices are built flow proceeds to operation 960-26 wherein a layer count is examined to determine if all layers have been built. If layers remain to be built flow proceeds to operation 960-28 wherein the layer count is incremented and flow returns to operation 960-2. When it is determined that all layers are built in operation 960-26 the PWB build is done.
While particular embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from this disclosure and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of this disclosure. The true spirit and scope is considered to encompass devices and processes, unless specifically limited to distinguish from known subject matter, which provide equivalent functions as required for interaction with other elements of the claims and the scope is not considered limited to devices and functions currently in existence where future developments may supplant usage of currently available devices and processes yet provide the functioning required for interaction with other claim elements. Furthermore, it is to be understood that the disclosure is solely defined by the appended claims. It is understood by those with skill in the art that unless a specific number of an introduced claim element is recited in the claim, such claim element is not limited to a certain number. For example, introduction of a claim element using the indefinite article “a” or “an” does not limit the claim to “one” of the element. Still further, the following appended claims can contain usage of the introductory phrases “at least one” and “one or more” to introduce claim elements. Such phrases are not considered to imply that the introduction of a claim element by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim element to disclosures containing only one such element, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an”; similarly, the use in the claims of definite articles does not alter the above related interpretation indefinite articles such as “a” or “an”.
This application is a continuation-in-part of and claims priority to application Ser. No. 16/773,944, filed Jan. 27, 2020, which is a continuation-in-part of application Ser. No. 15/175,014, filed Jun. 6, 2016, and now issued as U.S. Pat. No. 10,548,231, which is a continuation-in-part of application Ser. No. 14/392,408, which is a national stage application filed Jun. 1, 2016 of international patent application PCT/US2014/067986, filed Dec. 1, 2014, and claims priority to U.S. provisional patent application No. 62/053,796, filed Sep. 23, 2014, and U.S. provisional patent application No. 61/910,210, filed Nov. 29, 2013. This application incorporates by reference all materials of PCT/US2014/067986 and provisional applications Nos. 62/053,796, and 61/910,210 referenced above. Material of the provisional, PCT, national stage and prior CIP filings is intended only to augment the present disclosure and wording in the provisional or PCT applications is not to be interpreted as limiting this disclosure or requiring any material in the provisional applications as critical, indispensable, or a requirement unless so stated herein.
| Number | Date | Country | |
|---|---|---|---|
| 61910210 | Nov 2013 | US | |
| 62053796 | Sep 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16773944 | Jan 2020 | US |
| Child | 18114940 | US | |
| Parent | 15175014 | Jun 2016 | US |
| Child | 16773944 | US | |
| Parent | 14392408 | Jun 2016 | US |
| Child | 15175014 | US |
