Accelerated life tests of ceramic capacitors

Multilayer capacitors prepared from three different ceramics were tested under highly accelerated conditions of both voltage and temperature. Three types of breakdown were encountered: avalanche, fast thermal degradation, and diffusion or wearout. The goal was to determine whether data from highly accelerated life tests could be used to plot failure curves that would match those obtained at rated voltage and temperature conditions. Thus, the emphasis was on the wearout mode. The voltage accelerations were as high as 80% of the electric breakdown, and yielded voltage exponents between three and five. The temperatures were as high as 250°C. There was an activation energy for the temperature acceleration that closely matched that of the leakage current. Fast thermal degradation was encountered only at the high corner of the temperature-voltage matrix, and was easily recognized. It was found that data equivalent to that for a 1000-hour slightly accelerated life test can be generated in less than one day