Accelerated Life Testing of Capacitors

One of the problems facing the designer of modern electronic communication systems is the ultimate reliability to be achieved under service conditions. The required level of reliability together with the unavoidable complexity of present-day equipment calls for components having extremely low failure rates. Evaluation of the failure rates of such magnitude in the laboratory or pilot plant is practically impossible within a reasonable length of time and with a reasonable number of components. One way to meet this problem is the artificial reduction of the time to failure. This reduction of time or, in other words, the acceleration of life must be realistic to be of any value, which presents many problems in actual life testing. In recent years several papers have been published concerning statistical methods applied to life tests showing an exponential distribution of time to failure. These methods have been used as the basis for the design of an experiment to explore the acceleration obtainable in testing capacitors of recent design. Some results of this experiment estimating acceleration factors corresponding to increases in applied voltages and ambient temperatures are presented.