Patent Application
20130044448
The present invention relates generally to the art of electronic devices and, more specifically, to a method for mounting electronic components to a circuit board, an electric circuit board and/or an electric circuit board arrangement.
During assembly of electronic devices, components need to be interconnected to the circuit board and to other components. Some components, such as, for example, leaded devices, are placed onto the top of a circuit board pad and soldered to the substrate using reflow soldering. Other components, such as, for example, integrated circuits (ICs), are often wire bonded to a substrate. Many ICs and semiconductors require both active side and passive side connectivity. The bottom side of the device is often a ground connection or common node. In these cases, the assembly process can be complex, since two sides of the component, e.g., top and bottom, need to be attached to the substrate.
Currently, wire bonding and ultrasonic ribbon bonding are used to attach active side terminals to a substrate while simultaneously needing a conductive adhesive or soldering process for common node or ground connections. Flip chip and direct chip attach processes often use sequential soldering processes for both top and bottom side nodes.
Current methods require multiple manufacturing sequences to interconnect the top and bottom sides of the component. The required board real estate is typically large since wire bonds need encapsulated or overmolded post assembly. However, the known multi-step soldering processes are time consuming and require complex structures to connect the top and bottom sides of the die to the substrate.
Current approaches require that each side or edge of a die be connected at different steps in the assembly process. For example, a die with a back side ground first requires that a conductive material, such as, for example, silver filled epoxy, be placed on a substrate and the die placed onto the epoxy and cured. The top side connections are then made in a series of other assembly steps, such as, for example, wire bonding. Finally, the assembly is encapsulated to protect the wire bonds.
The present invention is directed toward overcoming one or more of the above-identified problems.
It is an object of the invention to provide a method for mounting a component to an electric circuit board, which particularly allows for an attachment of the top and bottom of the component.
A further object is to provide an electric circuit board comprising a component, particularly with the top and bottom ends of the component attached to the electric circuit board.
A further object is to provide an electric circuit board arrangement comprising a plurality of electric circuit boards and at least one component, particularly with the top and bottom ends of the component attached to an electric circuit board.
These and other objects are achieved by the features of the independent claim(s). The other claims, the description and the drawing include favorable embodiments of the invention.
A method for mounting a component an electric circuit board is proposed wherein the method comprises the steps of:
The cavity may be a pocket extending partially in the electric circuit board or may be a through-hole extending from top to bottom surface of the electric circuit board.
The proposed method is particularly useful in surface mount technologies (SMT) where components, particularly electric components, are mounted to an electric circuit board. During SMT assembly, components need to be interconnected to the circuit board and other components. Traditionally, multilayer circuit boards are formed in which layer to layer connections are created by metalized vias and copper plating. Components such as discrete capacitors and the like are assembled to the top and bottom of the electric circuit board by soldering processes.
Advantageously, the invention allows for the simultaneous interconnection of two sided, or top and bottom, metalized components, such as, for example, a die. In addition, the component may be placed in such a way that allows for a three dimensional use of the electric circuit board and space above the component. The inventive method replaces complex and expensive multiple sequential interconnections for top and bottom metal components. The invention removes the need to sequential assembly steps when connecting front and back side metalized components (such as, for example, a die) to a substrate (such as, for example, an electric circuit board).
The component may be an electric device having an end and side terminal, such as chip resistors and capacitors and the like. The component's terminals can be electrically connected to the electric circuit board in one process step. Alternatively, the component may be a device without external terminals, for instance an inductance such as an RFID transponder or the like.
In conventional electric circuit boards, the required board real estate made by conventional methods is larger than in the proposed method, since conventional wire bonds require encapsulated or overmolded post assembly. Multi-step soldering processes are time consuming and require complex structures to connect the top and bottom sides of the component to the electric circuit board.
The proposed method allows for simplification of processes, simultaneous bulk or mass assembly, top and bottom side soldering of two sided die components, use of the space above the embedded component for other assemblies, miniaturization, and low cost assembly methods as well as high yield and reliable processes.
According to a favorable development, the inventive method may further comprise the step of arranging the cavity adjacent at least one through-hole or via in the electric circuit board. Advantageously, the inventive method may further comprise the step of providing the at least one through-hole or via with an electrical conducting plating and connecting the component mechanically and/or electrically to the plating. Favorably, the metallic plating of the through-hole or via can be used as an electrical connection for connecting the terminals of the component to one or more electric contact pads of the electric circuit board. The through-hole penetrates the electric circuit board so that electrical connections to the component can be provided at the top as well as at the bottom surface of the electric circuit board. Alternatively, a via is a blind hole so that electric electrical connections to the component can be provided at the surface of the electric circuit board from where the via is accessible.
According to a favorable development, the inventive method may further comprise the step of coupling the component to the at least one circuit board by at least one of reflow soldering, solder wave, selective solder, and/or solder fountain. Advantageously, simultaneous bulk or mass assembly, and particularly top and bottom side soldering of two sided die components, can performed.
According to a favorable development, the inventive method may further comprise the step of arranging the component flush with at least one surface of the at least one electric circuit board or flush with a surface of a plating arranged at the at least one electric circuit board. Expediently, the space above the embedded component can be used for other assemblies. This allows for reduction of the required real estate of the electric circuit board.
According to another aspect of the invention, an electric circuit board is proposed, the electric circuit board comprising:
It is of advantage that a compact device can be provided which allows for miniaturization of the device. Electrical connections can be established in one process step.
The cavity may be a pocket extending partially in the electric circuit board or may be a through-hole extending from the top to bottom surface of the electric circuit board.
According to a favorable embodiment, the at least one component may be an electric device, particularly a device with top and bottom and/or side terminals. Electric connections to the component's terminals can be established by using, for example, metallic plating of through-holed and/or vias in the electric circuit board. Particularly, the cavity may be arranged adjacent one or more through-holes or vias. Expediently, the number of through-holes corresponds to the number of terminals of the component.
According to a favorable embodiment, the at least one component may be arranged flush with respect to a surface of the electric circuit board or may be arranged flush with respect to a surface of a plating on the electric circuit board. The arrangement is compact, as the space over the component may be used for arranging other components, such as, for example, electrical components at the surface of the electric circuit board.
According to another aspect of the invention, a method for making an electric circuit board arrangement is proposed, comprising the steps of:
During SMT assembly, components need to be interconnected to the circuit board and to other components. Traditionally, multilayer circuit boards are formed in which layer to layer connections are created by metalized vias and copper plating. Components, such as, for example, discrete capacitors, are assembled to the top and bottom of the circuit board by soldering processes. This invention uses the concept of stacking individual circuit boards on top of each other, and creating interconnects by soldering aligned features on each board. In particular, the present invention uses components embedded in the electric circuit boards to allow adjoined stacking of electric circuit boards. Stacked electric circuit boards allow unique three dimensional circuit configurations and provide higher assembly density and shape conformity than traditional SMT products.
The present invention provides a method for the simultaneous interconnection of two or more independent circuit boards. This allows high component density and effective use of volume within unconventional three dimensional shapes. It removes post SMT processes needed in standards three dimensional PCB methods (PCB=Printed Circuit Board), such as, for example, folding. The use of rigid materials fastened together in multiple layers provides increased robustness. The inventive method replaces multiple sequential interconnections for top and bottom metal components.
Currently, multilayer circuit boards are formed by traditional drill and plating of vias and through-holes to connect layers and surface mounting components on the top and bottom of the PCB. Embedding components inside PCBs is being done at board manufacture, however, it is an expensive and complicated process and the components cannot be changed or repaired once the board is laminated. The present invention allows for the use of lower cost high density circuit layer and uses an inexpensive and simple approach to embed components in the boards. Current methods for utilizing volume within three dimensional shapes involve folding flexible PCB material, which requires complicated process steps, and are more difficult and expensive to manufacture.
Particularly, current methods require multiple manufacturing sequences to interconnect the top and bottom sides of the component. Multi-step soldering processes are time consuming and require complex structures to connect the top and bottom sides of the die to the substrate.
Current approaches require components to be placed into the laminated structure of the electric circuit board during PCB manufacturing. This can potentially lead to component damage as lamination press temperatures and pressures are high. In addition, once the components are embedded in the laminate, they cannot be changed, reworked or probe tested directly. The present invention describes an alternative method for embedding components by using a stacked board structure and standard assembly processes.
The present invention allows for simplification of processes for embedding components, simultaneous bulk or mass assembly of two circuit boards, top and bottom side soldering of two sided dies, use of the space inside a board to embed components, miniaturization, low cost assembly methods, and the ability to utilize unconventional volume shapes.
According to a favorable development, the inventive method further comprises arranging the cavity adjacent at least one through-hole or via in the electric circuit board. A compact arrangement is achieved. Use can be made of existing electrical connections. Electric connections to the component's terminals can be established by using metallic plating of through-holed and/or vias in the electric circuit board. Particularly, the cavity may be arranged adjacent one or more through-holes or vias. Expediently, the number of through-holes corresponds to the number of terminals of the component.
According to a favorable development, the inventive method further comprises providing the at least one through-hole or via with an electrical conducting plating and connecting the component mechanically and/or electrically to the plating. A compact arrangement is achieved. Use can be made of existing electrical connections.
According to a favorable development, the inventive method further comprises coupling the component to the circuit board by at least one of reflow soldering, solder wave, selective solder, and/or solder fountain. Low cost assembly methods can be used.
According to a favorable development, the inventive method further comprises interconnecting the electric circuit boards by reflow soldering. Simultaneous bulk or mass assembly of two or more circuit boards and low cost assembly methods can be used.
According to another aspect of the invention, an electric circuit board arrangement is proposed, comprising at least one electric circuit board which comprises:
The present invention allows for simplification of processes for embedding components, simultaneous bulk or mass assembly of two circuit boards, top and bottom side soldering of two sided dies, use of the space inside a board to embed components, miniaturization, low cost assembly methods, and the ability to utilize unconventional volume shapes.
The cavity may be a pocket extending partially in the electric circuit board or may be a through-hole extending from top to bottom surface of the electric circuit board.
According to a favorable development, the one or more electric circuit boards may be coupled by solderable terminations of the component. A very compact design is achieved as well as simultaneous bulk or mass assembly of two or more circuit boards.
According to a favorable development, edges of the electric circuit boards may be arranged in a staggered arrangement. The stack of electric circuit boards can have unusual or unconventional volume shapes.
Further features, aspects, objects, advantages, and possible applications of the present invention will become apparent from a study of the exemplary embodiments and examples described below, in combination with the Figures, and the appended claims.
The present invention together with the above-mentioned and other objects and advantages may best be understood from the following detailed description of the exemplary embodiments, but not restricted to the embodiments, wherein is shown in:
In the drawings, like elements are referred to with equal reference numerals. The drawings are merely schematic representations, and are not intended to portray specific parameters of the invention. Moreover, the drawings are intended to depict only typical embodiments of the invention and, therefore, should not be considered as limiting the scope of the invention.
On a top surface 16 of the electric circuit board 10, two parallel through-holes 20 extending through body 12 of the electric circuit board 10 are arranged which are equipped with metallic platings 22 inside the through-holes 20 and on top of surface 16, as well as on the opposite back surface 18. By way of example, terminals 14 are arranged for placing and soldering electric components to surface 16 of the electric circuit board 10. The through-holes 20 can be pin through-holes, for instance, which are provided for mounting pins of leaded components to the electric circuit board 10.
The inventive method involves creating a cavity 40 in the electric circuit board 10 by a tool 30, such as an ablation or mechanical tool, e.g., a mill. The cavity 40 forms a pocket having a bottom 42 in body 12 of the electric circuit board 10 and is created between two or more adjacent plated through-holes 20 in the electric circuit board 10.
A component 50 is then placed into the cavity 40 (see
The cavity 40 becomes a mechanical resting place or placeholder for the component 50 during soldering. The component 50 may be placed into the cavity 40 by an automated process or by hand. The attachment process for terminals (not shown) on the component 50 can be created by a variety of methods, including, but not limited to, wave or bulk solder processes, printed solder and/or by using conductive adhesive.
Cavity 40 forms a pocket which is deep enough to accommodate the component 50 so that the component 50 is flush with top surface 16 of the electric circuit board 10 (
A solder print process can accomplish the electric connection between component 50 and the plating 22 of the through-holes 20. Alternatively, the solder 60 can be dispensed on the respective regions. The component 50 is placed into the cavity 40 and then the electric circuit board 10 is printed by traditional stencil or screen printing to deposit solder paste onto the terminal/plated through-hole regions (
A subsequent reflow process will cause the solder 60 to spread into the through-holes 20 and onto attachment pads of component 50 (
Reflow soldering is a process in which the solder paste 60, typically a sticky mixture of powdered solder and flux, is used to temporarily attach one or several electrical components to their contact pads, after which the entire assembly is subjected to controlled heat, which melts the solder, permanently connecting the electric joint. Heating may be accomplished, for example, by passing the assembly through a reflow oven or under an infrared lamp or by soldering individual joints with a hot air pencil or the like.
For a simple approach, the component 50, once placed into the cavity 40, may be passed over a molten wave or selective solder wave. The solder 60 wets the plating 22 of the through-holes 20 and moves into gaps between component 50 and adjacent plating 22 and reacts with and attaches to terminal pads (not shown in the Figures) of component 50 that are adjacent to the plated through-holes 20. Surface tension and capillary flow pulls the solder 60 into the through-holes 20 and the solder wetting force allows the solder 60 to flow onto the metal plating 22 to the component 50, as indicated in
The wave approach may require the use of a non-conductive adhesive to prevent the component from falling out of the pocket during soldering. A reflow retaining fixture could also be used to retain component 50 in the cavity 40 during soldering.
The component 50 has a terminal pad 52 on one main surface and two terminals 54 on the opposite main surface. By placing component 50 on edge in the cavity 40, the terminals 52, 54 are aligned with the respective through-holes 20 on each side of component 50 (one adjacent to terminal 52 and one adjacent to each of terminals 54). Component 50 is accommodated in the cavity 40 so that one side surface is flush with surface 24 of the plating 22 of the through holes 20.
In
To summarize, a simplification of the manufacturing process of the electric circuit board 10 can be achieved. The inventive method allows for simultaneous bulk or mass assembly. Top and bottom side soldering of two-sided dies can be achieved simultaneously. Low cost assembly methods and high yield and reliable processes can be employed to manufacture SMT devices.
The electric circuit board arrangement 200 comprises a multitude of individual electric circuit boards 300, 400, 500 stacked on top of each other and electrically connected by way of through-hole soldering. Solder paste 60 is reflowed to create electrical connections between the individual electric circuit boards 300, 400, 500. Within the individual bodies of the electric circuit boards 300, 400, 500, some of the multiple through-holes 320, 420, 520 are interconnected by metallic paths 302, 402, 502.
During SMT assembly, components need to be interconnected to the electric circuit boards 300, 400, 400 and to other components. Traditionally, multilayer circuit boards are formed in which layer to layer connections are created by metalized vias and copper plating. Components such as, for example, discrete capacitors, resistors and the like, are assembled to the top and bottom of the circuit board by soldering processes. According to this aspect of the invention, the individual electric circuit boards 300, 400, 500 are stacked on top of each other, and interconnects are created by soldering aligned features on each electric circuit board 300, 400, 500. Solder is indicated by reference numeral 60.
The present invention uses the embedded component concept as described in the preceding embodiments to allow adjoined stacking of boards. The stacked electric circuit board arrangement 200 allows for unique three dimensional circuit configurations and provides higher assembly density and shape conformity than traditional SMT products.
The method according to this aspect of the invention allows for simultaneous interconnection of two or more independent electric circuit boards 300, 400, 500. This concept allows high component density and effective use of the volume within unconventional three dimensional shapes. It removes post SMT processes needed in standards three dimensional PCB methods (PCB=Printed Circuit Board), such as, for example, folding. The use of rigid materials for the individual electric circuit boards 300, 400, 500 fastened together in multiple layers provides increased robustness of the arrangement. The inventive method replaces multiple sequential interconnections for top and bottom metal components.
Currently, multilayer electric circuit boards are formed by traditional drill and plating of vias and holes to connect layers and surface mounting components on the top and bottom of the PCB. Embedding components inside PCBs is being done at board manufacture. However, it is an expensive and complicated process and the components cannot be changed or repaired once the PCB is laminated. The present invention allows for the use of lower cost high density circuit layer and uses an inexpensive and simple method to embed components in the individual electric circuit boards. Current methods for utilizing volume within three dimensional shapes involve folding flexible PCB material, thus requiring complicated process steps, and are more difficult and expensive to manufacture.
Current methods require multiple manufacturing sequences to interconnect the top and bottom sides of the component. Multi-step soldering processes are time consuming and require complex structures to connect top and bottom sides of the die to the substrate.
Current approaches require components to be placed into the laminated structure of the board during PCB manufacturing. This can potentially lead to component damage as lamination press temperatures and pressures are high. In addition, once the components are embedded in the laminate, they cannot be changed, reworked or probe tested directly. The inventive method describes an alternative method for embedding components by using a stacked electric circuit board arrangement 200 and standard assembly processes.
Electrical connections between the individual electric circuit boards 300, 400, 500 can be established for instance by a board-to-board connection tab (
Alignment of the individual electric circuit boards 300, 400, 500 can be made by, for example, automated visual inspection or even by simple tooling pins 26, as shown in
The assembly of stacked electric circuit boards 300, 400, 500 is processed once in a reflow process, creating a high density, rigid three dimensional electric circuit.
To summarize, the invention allows, among other things, for simplification of processes for embedding components, simultaneous bulk or mass assembly of two or more circuit boards, and top and bottom side soldering of two sided dies. Use can be made of the space inside a board to embed components. Miniaturization of the arrangement, as well as low cost assembly methods, is possible. The invention also has the ability to utilize unconventional volume shapes.
It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teachings of the disclosure. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternate embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof. Additionally, the disclosure of a range of values is a disclosure of every numerical value within that range.
This patent application claims the benefit of co-pending U.S. Provisional Patent Application No. 61/524,774, filed on Aug. 18, 2011, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61524774 | Aug 2011 | US |
