Bonding Strength Test and Tensile Failure Study for Direct Plated Copper Ceramic Substrate

Bonding strength between the metal layer and the ceramic of ceramic substrate affects the packaging reliability of power devices. In this paper, the bonding strength of direct plated copper ceramic substrate (DPC) was tested by the tensile method, and the micro-morphology of DPC fracture surface and the elemental composition of DPC cross-section were analyzed. The results show that the average tensile strength is 11.78 MPa, but the fracture position of DPC in tensile test is the ceramic beneath metal layer. The fracture surface morphology of DPC conforms to the brittle fracture characteristics of ceramic. The micro-morphology of the cross-section of DPC and the EDS detection indicate that titanium atoms of the transition layer diffuse to the ceramic side and the copper side, which improves the bonding strength between the metal layer and the ceramic of DPC. In addition, the existence of ceramic pores makes ceramic prone to crack and brittle fracture when the metal layer of DPC is subjected to external tension. The study demonstrates that the bonding strength between the metal layer and the ceramic of DPC is higher than 11.78 MPa, and the weak part of DPC is the ceramic beneath the metal layer.