Comparison of reliability enhancement tests for electronic equipment

Techniques for fast and effective reliability enhancement testing of electronic equipment intended for use in harsh operating environments have been investigated. In particular, studies have been made of (i) a step-stress, swept-sine on random vibration profile (with combined thermal/humidity cycling) test, and (ii) a variety of tests utilising rapid thermal cycling and tri-axis vibration. The methodology is based on using established products, namely aerospace engine transient pressure units and automotive engine management units, for which considerable field reliability data exists, to assess the effectiveness of the tests at finding relevant faults. Our principal conclusions are as follows: (i) combining test variables is more effective than using them in isolation, (ii) triaxis vibration can lead to relevant failures very quickly provided the test is well designed and (iii) rapid thermal cycling is not particularly useful for products of the type studied here.