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Rapid Response Computer Aided Manufacture of Printed Wiring Boards The maintenance activities of the Department of Defense have a serious problem in maintaining military electronic systems. Many of these systems are so long lived that the original manufacturers no longer support them with spare parts. Printed wiring boards, which form the basic building blocks of electronic systems, are a particular problem, since they are custom made for each individual circuit. Complicating the problem is the fact that some of the critical components are no longer manufactured, requiring that the PWB be further customized to accommodate equivalent components that are available. Digital printing of conductive traces on conventional laminate and polymer film circuit substrates could facilitate testing and qualification of potential modifications and upgrades of existing systems. Once the design is frozen, the technology could provide spare parts on demand in quantities of one to a few hundred or a few thousand, easily and inexpensively. Digital printing of electronic wiring boards is ideally fitted to supply the need for large numbers of spare parts in a crisis. The objective of this program is to demonstrate and install a computer-automated alternative to the conventional plate-and-etch technology for producing printed wiring boards. The process is based on newly developed metallo-organic decomposition chemistry for direct, additive metallization of holes and printing of circuit traces. The new technology, named ParmodÒ, has been used to prepare demonstration circuits with pure copper conductors on laminate substrates which are believed to be the equivalent of conventional plate-and-etch circuits. In Phase I, samples were prepared by screen-printing the traces, together with a process whereby the through holes were given a uniform coating of ParmodÒ copper metallization. This approach has provided circuits with promising performance. It has the potential for digital interfacing with the CAD design function by direct write of the screens needed to print the traces, the hole metallization, the solder mask and the labels. Adhesive coatings for applying ParmodÒ to rigid substrates were evaluated and a suitable adhesive and application technique were demonstrated. A test vehicle in current demand for military maintenance was identified and samples were prepared for functional testing as well as accelerated life testing to evaluate their suitability for military use. Additional samples have been subjected to accelerated life testing and thermal shock testing. The results show that ParmodÒ has good prospects for successful implementation as a flexible manufacturing system for military and commercial applications. A stepwise program to introduce the ParmodÒ technology to DoD maintenance activities based on the successful results of Phase I is recommended. This would be Phase II of the original vision of this project. It is recommended that these Phase II efforts be combined with other research efforts being conducted by CTMA or other DoD programs, if possible. A potential DoD project that could be a vehicle for further efforts of this process would be the investigations on Mesoscopic Integrated Conformal Electronics (MICE) program. By integrating the Phase II efforts into a program such as MICE, it is possible that some of the economic issues could be resolved. If these further efforts could be realized within the scope of a program such as MICE, the benefits of this overall program would be:
Program Manager: Mike Gnam, mikeg@ncms.org, (734) 995-4971
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