PLASTIC-ENCAPSULATED MICROCIRCUIT RELIABILITY AND COST-EFFECTIVENESS STUDY

This study evaluates the reliability and cost-effectiveness of using c ommercial plastic-encapsulated microcircuits (PEM) in a typical milita ry system, with a view to increasing their acceptability in military a pplications. The cost comparison indicates an average 6-fold decrease in cost when commercial devices are used. Assurance testing did not re veal any special problems with commercial parts. Thus, if commercial P EM were proven to be sufficiently reliable for an intended military ap plication, large cost savings would be gained by using them instead of hermetic packages. The 4.5-sigma enhanced inspection program and the process-control methods suggested here would enhance the manufacturing yield of the PLGR (precision lightweight global positioning system re ceiver) by encouraging improvements in the manufacturing process while simultaneously cutting the cost of a 100% rescreen to qualify the fin al product. Neither the requirements assurance tests (including the st ep-stress test-analyze-and-fix test), nor the reliability demonstratio n test, nor the operational test, showed more failures than are typica l for any new development, and no problems unique to PEM were observed . Thus, the use of PEM did not lead to any special problems that cause d PLGR-use specifications to be violated. Complete failure analysis of the isolated parts is in progress, and the results will help to under stand the specific reliability issues involved with the use of PEM in military systems. These issues can then be addressed to improve the ac ceptability of such devices in future military applications.