Electronic Part Failure Rates in Space Environments

Much conjecture exists regarding the special effects of space environments as reliability stressors on common electronic parts. To understand the unique risks associated with these additional factors, it is useful to envision their presence as superimposed sources of activation energy. This, in turn, demands a general mathematical model for part failure rate synthesis which relates statistical risk with energy level. Such a mathematical model has been developed and is worthy of close examination from the view-point of additional space environment risks. Thus, an energy level concept affords mathematical equations from which the statistical risks in ``unproven´´ operational environments can be inferred from an extrapolation of a wealth of conventional operational experience. This paper contends that advances in the art of space material test and evaluation must have their roots in a comprehensive understanding of terrestrial tests and statistical failure rate criteria. Any useful comprehension must be based upon a rank order of part stressors where ground environment factors are essential prerequisites. Once examined from an energy viewpoint, failure tendencies and their underlying material mechanisms can be usefully depicted mathematically using energy as a helpful common denominator. It remains then to deliberate upon the appropriate material test evidences to establish tables of part usage risk for space environments with the same level of completeness as has been established for terrestrial operating conditions.