Novel Failure Mechanism and Anomalous Acceleration Factor on a Beam-Lead IC

In this paper, we identify a previously unreported corrosion mechanism as a primary cause of field failure in a particular beam-lead sealed-junction IC design. This mechanism has been reproduced under laboratory bias-humidity-temperature (BHT) test conditions. We determine an acceleration factor for this mechanism by comparing the failure distribution obtained in BHT tests with that from a field tracking study. Because a previously published reliability model for BHT aging of beam-lead ICs grossly overestimates this observed acceleration factor, it appears that this model does not adequately describe the corrosion mechanism discussed in this paper.