Commercial Plastic Encapsulated Microcircuits for Naval Aviation Applications

o determine the effects of uncontrolled long-term dormant storage on plastic encapsulated microcircuits, the Applied Physics Laboratory evaluated 92 commercial samples, some as old as 28 years, from multiple manufacturers and technologies. The presumption is that if old parts have not degraded after 20 or 30 years of uncontrolled long-term dormant storage, then vastly superior current products will survive similar periods under similar conditions. Results from destructive physical analysis 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, suggesting that this technique might not be a good method for screening plastic encapsulated microcircuits. No direct relationship was found between corrosion and moisture content. In addition, oxygen plasma etching was found to be a very effective method for performing destructive physical analysis on plastic encapsulated microcircuits. (