Modeling and analysis of mesh pattern influences on DBC thermal cycling reliability

Abstract

CTE mismatch between direct bonding copper (DBC) layers results in excessive thermal stress, causing the fatigue cracks and delamination after long time run, which deteriorate the reliability of DBC and the power module in the end. A method of designing mesh patterns on DBC is proposed in this paper to release the thermal stress. At the same time, the comprehensive analysis of the relationship between the mesh patterns and the DBC reliability is made. The finite element method is used to simulate the distributions and variations of thermal stress on DBC with different mesh patterns. Both the theoretical and experimental results prove the function of the thermal stress release for the mesh on DBC. Furthermore, the meshes on the edge or corner, and with smaller size are most effective. In experiment, compared with the DBC without mesh, the thermal cycling lifetime for the DBC with the optimized mesh pattern could be improved by 15 times.