Thermomechanical Reliability of Bond Wires in Power Modules Subjected to Power Cycling

In the context of the expanding automotive market, power modules have emerged as key components, driving the need for compact devices, enhanced thermal management, and higher power density. These modules, which offer considerable benefits over discrete components, are subjected to thermomechanical stresses throughout their life cycle, primarily due to active power cycling and passive temperature cycling, which can induce various failure modes. This paper focuses on the reliability of power modules under the specific conditions of power cycling. The effect of varying wire number and diameter on the thermomechanical response and reliability of power modules is assessed through a combination of experimental reliability tests and finite element method simulations. It has been demonstrated that the robustness of power modules, in terms of the number of cycles before failure, is significantly improved by a greater number of wires with lower diameter. This comprehensive analysis of bond wire reliability under power cycling conditions offers valuable insights into their failure mechanisms, contributing to the enhancement of power module design and reliability. This work is particularly pertinent as the industry moves towards increased reliance on power modules, especially for EVs, where power electronics reliability is paramount.