Mathematical Formulation with Finite Element Simulation for Thermo-Mechanical Stress Analysis in Power Electronic Modules

Abstract

The strong thermo-mechanical loading of power electronic modules due to high power dissipation and thermal cycling produces stress concentration, resulting in lower operational reliability. This paper introduces a mathematical modeling and finite element simulation model that is coupled to predict temperature field and thermo-mechanical stresses in multilayer power electronic modules. A three-dimensional transient finite element model in which there are about 185,000 tetrahedrals and 248,000 nodes is used to solve the governing transient heat conduction and linear thermoelastic equations. There was simulation with power dissipation of 20 W to 100 W and ambient temperature of 25 °C. Junction temperature reached the maximum of 54.8 °C (132.6 °C) and von Mises stress reached the maximum of 68.4 Mpa (186.7 Mpa). Mesh convergence achieved a numerical variation of less than 1.5% and model validation by comparison with published finite element studies had an average prediction error of 3.1%. The presented framework offers a reliable and computationally efficient instrument to assess reliability and optimize thermal design of the latest power electronic modules.