2D Finite Element analysis of IGBT solder joint

2D and strip/slice Finite Element models for IGBT substrate mount-down solder joints are compared with full 3D models for the fatigue lifetime analysis of the solder joints. Cyclic temperature loading is applied to the solder joint structures and volume weighted equivalent plastic work density per temperature cycle in solder joints is calculated for all the models. Results show that 2D and slice models yield much lower values than the 3D model. As the models´ geometry and material properties change, damage indicator values of the 3D models change linearly with the values of the 2D models but the coefficients of the linear equation are not the same for all the design variables. It can be concluded that if a lifetime model for IGBT solder joints is obtained using 2D finite Element analysis, it would be much limited in accuracy and predictive power in reliability analysis and design.