Reliable Application of Plastic Encapsulated Microcircuits for Small Satellites

Advances in electronics technology - more than in any other field - have enabled small satellites to perform important missions. But electronics (and its associated software) still represents the principal cost driver for many satellites. A key to reducing the cost of flight electronics - as well as improving reliability is to fly the most recent, most capable integrated circuits (ICs). The most desirable, state-of-the-art ICs for lightsat applications usually appear first in plastic, non-hermetic packages. Use of these plastic-encapsulated microcircuits (PEMs) for high reliability space hardware has traditionally been forbidden because of the perceived reliability risk due to moisture penetration, contamination, internal damage from thermal cycling, and other concerns. Yet the reality of today's aerospace market is that many desirable ICs will never be made available in hermetic packages. Fortunately, over the last decade, manufacturers have significantly improved the reliability of PEMs. The Applied Physics Laboratory (APL) examined the use of PEMs for spaceflight application, taking into account reliability, board design, parts storage, fabrication, thermal, radiation, contamination, failure analysis, and other issues important to lightsat designers. This paper summarizes APL's findings and outlines the conditions under which some PEMs can be safely used in space. Case studies are cited to show that, paradoxically, use of a slightly less reliable plastic part can sometimes improve the overall reliability of small satellite subsystems.