CHALLENGES USING LEGACY PARTS IN NEW MISSION CRITICAL APPLICATIONS CASE STUDIES OF HERMETIC ISSUES FOUND IN FULLY QUALIFIED PARTS MANUFACTURED IN THE 1990's

摘要

Military contractors regularly design in electronic components that were manufactured and reliability screened from previous programs. Over the past several years a number of these efforts have encountered problems when reliability re-screening demonstrated high moisture content in excess of specifications, putting missions in jeopardy. Several manufacturers of these parts contacted Pernicka Corporation to help determine the cause of the failures and identify parts that could be used in mission critical application. This paper will discuss case studies of a large number of parts, some of which were manufactured as long ago as 1996, that initially failed moisture specifications upon re-screening. The discussion will include the causes and mechanisms of the failures and the method used to validate which parts met or exceeded hermitic and moisture requirements. One of the tools used in the evaluations is the recently approved Cumulative Helium Leak Detection (CHLD) method. A brief overview of the method and how it was successful in qualifying parts will be included in the paper.