COMMERCIAL PLASTIC ENCAPSULATED MICROCIRCUITS FOR NAVAL AVIATION APPLICATIONS

To determine the effects of uncontrolled long-term dormant storage on plastic encapsulated microcircuits, the Applied Physics Laboratory eva luated 92 commercial samples, some as old as 28 years, from multiple m anufacturers and technologies. The presumption is that if old parts ha ve not degraded after 20 or 30 years of uncontrolled long-term dormant storage, then vastly superior current products will survive similar p eriods under similar conditions. Results from destructive physical ana lysis revealed that only two plastic encapsulated microcircuits, both 28 years old, exhibited corrosion. Regardless of age, C-mode scanning acoustic microscopy revealed delaminated areas in most parts, suggesti ng that this technique might not be a good method for screening plasti c encapsulated microcircuits. No direct relationship was found between corrosion and moisture content. in addition, oxygen plasma etching wa s found to be a very effective method for performing destructive physi cal analysis on plastic encapsulated microcircuits.