DBC substrate in Si- and SiC-based power electronics modules: Design, fabrication and failure analysis

In this paper, the failure mechanisms of the direct bonding copper (DBC) substrate under the condition of temperature cycling are studied. The cyclic temperature considered ranges from -40°C to 200°C. Furthermore, finite element method is used to optimize the DBC substrate structure in order to reduce the thermal stress and improve the reliability and fatigue life of power modules. Various factors are taken into account to optimize the DBC substrate, such as the thicknesses of copper layer, with or without dimples on copper layer, and the angle of copper coating. The simulation results showed that thinner copper layer thickness, smaller copper coating angle, or copper layer with dimples could decrease the plastic strain at the edge of the substrate, which make the DBC substrate have a longer lifetime under temperature cycling condition.