Height Optimization for a Medium-Voltage Planar Package

Due to the thin structure employed in planar packaging, the high electric field intensity may occur inside the power module, leading to degradation of the dielectric performance. To resolve this issue, the Metal-Posts-Interconnected Parallel Plate Structure (MPIPPS) is used to reduce the high field concentration in the power module. However, the high bonding joint in MPIPPS will cause high thermo-mechanical stress in the solder layers. In this paper, a methodology to optimize the joint height based on the trade-off between thermo-mechanical performance and dielectric performance of the power module is proposed. The impact of the joint height on thermo-mechanical stress and dielectric performance of the module is investigated quantitatively using ANSYS and Maxwell simulations. The results show that with 0.4 mm joint height and Nusil R-2188 encapsulation, the power module can achieve 3 kV breakdown voltage. The experimental results agree with the simulation results.