Planar Power Module With Low Thermal Impedance and Low Thermomechanical Stress

In recent years, there has been growing demand to increase the power density in power modules. Therefore, the thermal management of power modules has become more and more critical. In this paper, we show that conventional single-sided power module with wire-bond connection cannot achieve both good steady-state and transient thermal performance under high heat transfer coefficient conditions. The plate-bonded power module has been proposed to resolve this issue. However, the thick copper plate embedded in the power module induces large thermomechanical stress during temperature cycling, leading to poor reliability. To reduce the thermomechanical stress without significantly compromising the thermal performance, a trenched copper plate power module is designed and presented. A parametric study shows that the maximum von Mises stress and plastic strain in the solder layer can be reduced by 18.7%, and 67.8%, respectively, if the single piece of copper plate is replaced by a 3 x 3 trenched copper plate.