Storage Failure Mechanism Analysis and a Prior Information Prediction of Optocouplers Based on Failure Mechanism Verification Tests

Abstract

The effectiveness of an accelerated storage test depends on the consistency between the failure mechanism of the product in an accelerated storage environment and that in a natural storage environment. Therefore, before performing an accelerated storage test, information of the failure mechanism of the product, thus the measurable parameters characterizing the degradation and the upper limit of the acceleration stress is necessary to be determined. To address these problems, a stepwise temperature stress accelerated degradation test of a missile optocoupler was designed and conducted. The failure mechanism of the optocoupler was determined based on physical failure theory and physical and chemical analysis. The test results showed that the optocouplers had three failure modes in storage, which were degradation failure caused by forward voltage drop rise and leakage and sudden failure caused by burst open circuit. The key performance parameters were the forward voltage drop and the reverse leakage current. The upper limit temperature of the accelerated storage test was 120 °C. The above results provide a reasonable basis for future degradation modeling and accelerated storage test design to accurately assess optocoupler storage life.