Power semiconductor device technology needs highly efficient heat dissipation system having a chip bonding layer with high thermal conductance and reliability. This paper reports on 3D thermal stress profile and deformation with multi-physics solver for the system having Ag sintered bonding layer as a new chip attachment technology. The results clarified the reliability properties under thermal cycling test for Ag sintering chip attachment. It was found that the maximum stress value of Ag sintered bonding layer is lower than that of conventional solder layer, and the stress is concentrated at the upper edges for both Ag sintered and conventional solder bonding layers. DCB substrate model where the upper Cu layer thickness is thicker than the lower Cu layer thickness, showed the downward convex warp by the contraction difference between two Cu layers.