Use of highly accelerated life test (HALT) to determine reliability of multilayer ceramic capacitors

Interpretation of highly accelerated life test (HALT) failure data requires the use of the correct statistics. Wiebull and log-normal distributions were compared to the exponential distribution. While the exponential is a special case of the Wiebull, the log-normal was found to be sensitive to secondary populations which have a significant influence on the early life of the capacitor. These populations may have predicted lifetimes up to 20 years, and are thus significant. The effect of increased temperature and voltage on the acceleration factors normally used by industry is investigated. From these, criteria for burn-in and failure rate determination can be determined which would provide the user with a measure of reliability of the product being used. Some of the factors which affect the results can be related to process conditions so that a measure of manufacturing process capability is also obtained