Methods of reliability design of semiconductor power devices

Reliability design of semiconductor power devices requires a classification of operating modes, calculation of the reliability indicators for each class, and convertibility from set of operating modes to another, either in the same class or in another one. There are noncyclic and cyclic modes of operation, the probability of failure free operation or the failure rate in noncyclic modes depending foremost on the mean temperature of the device and the applied voltage. Cyclic operation is characterized by temperature cycles, pulse cycles, current overloads, or combinations thereof. Appropriate relations for the reliability indicators as functions of the corresponding variables are established for each type of operating mode.