Plastic Encapsulated Microcircuits (PEMS) offer advantages of size, weight, cost, and availability. The traditional barrier to their use in highly reliable systems ha been their perceived lower reliability in space and aerospace applications. In spite of his perception, the space and aerospace electronics industries have begun to reconsider the use of PEMs due to 1) improvements in reliability of PEMs, as evidenced by their use in the automotive industry; 2) improved methods of accelerated testing and deterministic reliability prediction: 3) awareness that factors other than "part reliability" are more important than previously thought; and 4) concerns that many hermetic part types may not be available for future designs of space systems.

For high-reliability applications, PEMs cannot be implemented in product designs and parts lists simply by replacing military part numbers with their commercial counterparts. The entire system of parts specifications, qualification, screening, and control needs to be modified to accommodate the unique features of PEMs.