Influence of Power Cycling Test Methodology on the Applicability of the Linear Damage Accumulation Rule for the Lifetime Estimation in Power Devices

The lifetime of power semiconductor devices, operating under a given mission profile and subjected to power cycling stress, is conventionally estimated under the assumption of linear damage accumulation rule, that is the application of the Miner's rule. To this purpose, lifetime models must be properly defined allowing to take into account for the relevant parameters of power cycling stress. This work shows how to estimate a cumulative distribution function in the case of an arbitrary temperature swing profile, starting from the statistical distribution at constant power cycling conditions. It is found that the accuracy of the linear damage accumulation rule is related to the experimental methodology adopted for power cycling tests. A detailed experimental activity is carried out on packaged IGBT devices, providing useful guidelines for the definition of lifetime models to be adopted in the Miner's rule.