Printing conductive patterns (e.g., conductive wires) on substrates (e.g., a circuit board) may leave faulty disconnections or poor connections (i.e., faults) that compromise functionality and lifetime of the conductive patterns. To repair the faults, the substrates may be reloaded into a printing machine and the printing may be re-done or the faults manually rewritten with a conductive pen. However, these methods are not only time consuming but also unreliable and expensive.
In general, in one aspect, the invention relates to a method for detecting faults in a conductive circuitry. The method comprises: printing the conductive circuitry on top of a substrate using a printing head; heating the conductive circuitry with a heat source; scanning the heated conductive circuitry with a non-contact thermal detector; detecting, with the non-contact thermal detector and concurrently with the printing of the conductive circuitry, the faults where the printing head failed to print; and reprinting the faults with the printing head.
In general, in one aspect, the invention relates to a non-transitory computer readable medium (CRM) storing instructions that causes a print server to perform an operation for detecting faults in a conductive circuitry embodied therein. The operation comprises: printing the conductive circuitry on top of a substrate using a printing head; heating the conductive circuitry with a heat source; scanning the heated conductive circuitry with a non-contact thermal detector; detecting, with the non-contact thermal detector and concurrently with the printing of the conductive circuitry, the faults where the printing head failed to print; and reprinting the faults with the printing head.
In general, in one aspect, the invention relates to a system for detecting faults in a conductive circuitry. The system comprises: a memory; and a computer processor connected to the memory. The computer processor causes a print unit coupled to the system to: print the conductive circuitry on top of a substrate using a printing head; heat the conductive circuitry with a heat source; scan the heated conductive circuitry with a non-contact thermal detector; detect, with the non-contact thermal detector and concurrently with the print of the conductive circuitry, the faults where the printing head failed to print; and reprint the faults with the printing head.
Other aspects of the invention will be apparent from the following description and the appended claims.
Specific embodiments of the invention will now be described in detail with reference to the accompanying figures. Like elements in the various figures are denoted by like reference numerals for consistency.
In the following detailed description of embodiments of the invention, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.
In general, embodiments of the invention provide a method, a non-transitory computer readable medium (CRM), and a system for detecting and correcting faulty-printed conductive circuits (i.e., conductive pattern) on a substrate (e.g., a circuit board) concurrently with a process of printing the conductive circuit on the substrate. When a printing system prints a conductive pattern (e.g., conductive lines that may connect circuit elements of a circuit board) with a printing head on a substrate, any type of errors in the printing process (e.g., low level of conductive ink, incorrect pressure in a supply tank to the printing head, an error in the printing head, contamination on the substrate, or cracks in the substrate) may occur. These errors may leave areas of poor connections (i.e., faults) on the substrate that were not part of the originally-designed conductive pattern.
In one or more embodiments of the invention, the buffer (101) may be implemented in hardware (i.e., circuitry), software, or any combination thereof. The buffer (101) is configured to store a printing-pattern file (102) of the conductive pattern. In one or more embodiments, the printing-pattern file (102) may include a design of the conductive pattern and print instructions. The printing-pattern file (102) may be an image and/or a graphic (e.g., a stereolithography (STL) format, a virtual reality model language (VRML) format file, an additive manufacturing file (AMF) format, etc.). The printing-pattern file (102) may be obtained (e.g., downloaded, created locally, etc.) from any source.
In one or more embodiments of the invention, the printing engine (103) may be implemented in hardware (i.e., circuitry), software, or any combination thereof. The printing engine (103) may be coupled to a printing head that prints the conductive pattern based on the printing-pattern file (102) on a substrate. In one or more embodiments, the detection system (104) may be implemented in hardware (i.e., circuitry), software, or any combination thereof. The detection system (104) detects the faults in the conductive pattern. Upon receiving information about the faults (e.g., the locations of the faults) from the detection system (104), the printing engine (103) reprints the faults.
In one or more embodiments of the invention, the detection system (104) may include a heating unit that heats the conductive pattern to radiate a thermal signal profile (e.g., infrared (IR) waves). The detection system (104) may also include a non-contact thermal detector (e.g., an IR camera) that can scan the conductive pattern in a non-contact mode (i.e., no physical contact between the thermal detector and the conductive pattern) in concurrent (i.e., simultaneously) with the printing of the conductive pattern. This captures the thermal signal profile of the conductive pattern. In the thermal signal profile of the conductive pattern the faults do not radiate or have a weaker radiation in comparison with correctly-printed areas of the conductive pattern because the faults have no conductive material or have less conductive material than the correctly-printed areas. Thus, the faults may be detected and located on the substrate.
In one or more embodiments of the invention, the non-contact thermal detector may be a thermal sensor array (i.e., an array of thermal sensors or thermal sensor pixels that are arranged side-by-side). The thermal sensor array may be any one of a thermal IR, line-scanner, fiber optic thermometer, etc.
In one or more embodiments of the invention, after locating a fault, the printing head may move to the location of the fault and reprint the conductive pattern in that location. The printing head may pause the printing of the circuit pattern immediately after a fault is located and moves to the location of the fault to reprint the conductive pattern in that location. Alternatively, the printing head may complete printing a part or the whole conductive pattern and then move back to the location of the fault to reprint in that location.
In one or more embodiments of the invention, artificial intelligence (AI) or machine learning techniques may be used to improve the detection of the faults. For this purpose, common failure patterns (e.g., failure patterns for a specific printer type, a specific printing material formulation, etc.) may be collected and analyzed to prepare a common failure pattern database. For example, by using a specific type of substrate, printer, or printing materials at a specific ambient temperature or in a specific altitude, the faults may be more likely to happen toward specific locations of the substrate. The AI and machine learning techniques may modify printing techniques based on the information stored in the common failure pattern database that includes results of the analysis of the common failure patterns in these conditions to better eliminate the faults.
In one or more embodiments of the invention, detection and reprinting of the faults concurrently with the printing prevents printing-rework post-processes that may be expensive, time consuming, and unreliable. In addition, bonding wires to a reworked conductive pattern may be challenging. Moreover, because printing materials may vary from batch to batch, repairing the faults manually or in a printing-rework post-process may create non-uniform conductive patterns.
The processes described above in reference to
Although the system (100) is shown as having three components (101, 103, 104), in other embodiments of the invention, the system (100) may have more or fewer components. Further, the functionality of each component described above may be split across components. Further still, each component (101, 103, 104) may be utilized multiple times to carry out an iterative operation.
Referring to
In STEP 210, as discussed above in reference to
In one or more embodiments of the invention, the printing materials may have both highly electrical and thermal conductive characteristics, such as silver nanoparticles, copper nanoparticles, indium tin oxide (ITO) particles, graphene flakes, etc.
In one or more embodiments of the invention, the substrate materials may have both highly electrical and thermal insulating characteristics, such as glass, a polymer (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc.), and polychlorinated biphenyl (PCB). The substrate materials may be either optically transparent or opaque for visible wavelength (400 nm-750 nm). For the case of a non-contact thermal detector being underneath the substrate, the substrate materials may be transparent in a range of IR wavelength (e.g., an IR range between 1-14 μm).
In one or more embodiments of the invention, the printing head deposits the printing materials in a pattern of lines. In one or more embodiments, the pattern of lines in the conductive pattern may have a width as thin as a few microns or as wide as a few millimeters.
In STEP 215, as discussed above in reference to
In STEP 220, as discussed above in reference to
In one or more embodiments of the invention, the non-contact thermal detector may have a resolution of a few microns.
In STEP 225, as discussed above in reference to
In STEP 230, as discussed above in reference to
In STEP 240, as discussed above in reference to
In one or more embodiments, as discussed above in reference to
In one or more embodiment of the invention, the printing head may pause the printing of the conductive pattern immediately after locating the fault and move to the location of the fault to reprint the conductive pattern in that location. Alternatively, the printing head may complete printing a part or the whole conductive pattern and then move back to the location of the fault to reprint the conductive pattern in that location.
In one or more embodiments of the invention, STEPS 205-240 of
In one or more embodiments of the invention, to increase a temperature of the conductive pattern (330, 530) with respect to a temperature of the substrate (310, 510), the heating unit (350, 550) heats the conductive pattern (330, 530).
In one or more embodiments of the invention, the non-contact thermal detector (340, 540) scans a thermal signal profile of the conductive pattern (330, 530) and detects the faults (331, 531) based on a heat profile of the conductive pattern (330. 530).
In one or more embodiment of the invention, the non-contact thermal detector (340, 540) may be disposed in such a way that moves and scans across the print direction (i.e., a length-wise direction across a length of the substrate (310, 510)) while being synchronized with movements of the printing head (320, 520). For example, the printing head (320, 520) and the non-contact thermal detector (340, 540) may be disposed on a lever (e.g., a rigid holder that holds the printing head (320, 520) and the non-contact thermal detector (340, 540)) in such a way that a distance between the printing head (320, 520) and the non-contact thermal detector (340, 540) along the print direction is constant as the printing head is printing.
In one or more embodiments of the invention, the conductive pattern (330, 530) may include multiple intentional gaps (332, 532) between conductive lines (i.e., gaps that appear in the printing-pattern file) in the conductive pattern (330, 530). To prevent mistakenly capturing the intentional gaps (332, 532) as faults (331, 531), the non-contact thermal detector (340, 540) may stop scanning (e.g., turn scanning ON and OFF, pause the scanning, etc.) at the intentional gaps (332, 532). Alternatively, there may be a device (e.g., a computer with instructions) that interfaces the non-contact thermal detector (340, 540) and the printing head (320, 520) that excludes the thermal signal profile of the intentional gaps (332, 532) from the reprinting process.
As seen in
In one or more embodiments of the invention, mathematical calculations on the thermal signal profile such as first order derivative of the thermal signal profile may be used to locate the fault (331). Mathematical calculations may be used when a signal to noise ratio of the thermal signal profile is high. For example,
As seen in
In one or more embodiments of the invention, the heating units (550A, 550B) at the ends of the substrate (510) may be designed in such a way that by switching both of the heating units (550A, 550B) to ON, the temperature gradient across the printing line may be modified (e.g., in to a uniform temperature along the print direction).
One of ordinary skill in the art will appreciate that other mathematical methods (e.g., higher order derivatives of the thermal signal profile) may be used to determine the locations of the faults.
Embodiments of the invention may be implemented on virtually any type of computing system, regardless of the platform being used. For example, the computing system may be one or more mobile devices (e.g., laptop computer, smart phone, personal digital assistant, tablet computer, or other mobile device), desktop computers, servers, blades in a server chassis, or any other type of computing device or devices that includes at least the minimum processing power, memory, and input and output device(s) to perform one or more embodiments of the invention. For example, as shown in
Software instructions in the form of computer readable program code to perform embodiments of the invention may be stored, in whole or in part, temporarily or permanently, on a non-transitory computer readable medium such as a CD, DVD, storage device, a diskette, a tape, flash memory, physical memory, or any other computer readable storage medium. Specifically, the software instructions may correspond to computer readable program code that when executed by a processor(s), is configured to perform embodiments of the invention.
Further, one or more elements of the aforementioned computing system (700) may be located at a remote location and be connected to the other elements over a network (712). Further, one or more embodiments of the invention may be implemented on a distributed system having a plurality of nodes, where each portion of the invention may be located on a different node within the distributed system. In one embodiment of the invention, the node corresponds to a distinct computing device. Alternatively, the node may correspond to a computer processor with associated physical memory. The node may alternatively correspond to a computer processor or micro-core of a computer processor with shared memory and/or resources.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.