Evaluating plastic assembly processes for high reliabilityapplications using HAST and assembly test chips

摘要

We demonstrate the use of HAST and Assembly Test Chips (ATCs) toevaluate the susceptibility of epoxy molding compounds to moistureinduced corrosion of Al conductors. We show that the procedure issufficiently sensitive to discriminate between assembly processes usedby different molding facilities. Our data show that the location in timeof the “knee” in the failure distribution is dependent onmaterial properties of the epoxy. Reducing the failure rate in the earlyor “extrinsic” region of the time-failure distribution iskey to achieving high reliability. We examine the failure modes in theextrinsic region for test chips encapsulated with a number of highquality molding compounds in an attempt to better understand this region