Analytical reliability performance maps for bond wire interfaces in power modules under cyclic thermomechanical loads

Reliability of power modules based on Insulated Gate Bipolar Transistors (IGBTs) is majorly challenged by thermomechanical fatigue, especially at the wirebond-chip interface where lift-off failure mechanisms commonly occur. This paper introduces a novel analytical model tailored to the geometry and material properties of the wirebond-chip interface to rapidly predict reliability performance maps highlighting different zones of expected elastoplastic behaviors under thermomechanical cycling. The model integrates a thermomechanical stress formulation with a Dugdale Cohesive Zone Model to capture plastic zone development at the interface and applies the Lower Bound Shakedown Theorem to identify elastoplastic behaviors without having to perform full cyclic incremental finite element simulations. The proposed analysis enables classification of cyclic behaviors into elastic, shakedown, and alternating plasticity regimes, providing a deeper understanding of the transition to low cycle fatigue at the shakedown/alternating plasticity boundary. Analytical predictions are compared to 2D finite element analyses, which confirm the ability of the model to capture key features like plastic strain evolution and its stabilization. The proposed modular model serves as a rapid and adaptable tool for early-stage reliability assessment as a function of geometric, material, and loading parameters.