Sensitivity Analysis of Simulation-Based Lifetime Extrapolation in the Low Temperature Swing Regime for Power Modules Stressed in Power Cycling Tests

Nowadays, lifetime modelling of power modules in DC-power cycling tests relies more and more on simulation based methods due to the improved ruggedness of the modules. Especially for low-load collectives which occur frequently in practice, simulations are indispensable, because load cycle testing affords too much time. Consequently, the estimated lifetime becomes sensitive to the respective modelling strategy. This sensitivity with respect to the material model for the large area substrate solder connecting the baseplate and substrate of a powermodule, and the cyclic stabilization behavior of the stress-strain hysteresis is investigated. The specific material models are the viscoplastic Chaboche and Anand models. For the parameter identification an accelerated approach is used. Lifetimes in the low load temperature regime are estimated using an energy-based model for lifetime estimation. Results show that the Chaboche model represents the experimental data better compared to the Anand model. Furthermore, the sensitivity study reveals that the material model has a huge influence on the extrapolation of lifetime. The Chaboche model yields higher lifetimes compared to the Anand model. Lastly, it is shown that the stabilization behavior interacts with the load and material model and significantly influences the lifetime.