US Patent 7579677 Semiconductor device and method for manufacturing thereof

In a power semiconductor device, a joint between the power semiconductor element and frame plated with Ni is composed of a laminated structure comprising, from the power semiconductor element side, an intermetallic compound layer having a melting point of 260° C. or higher, a Cu layer, a metal layer having a melting point of 260° C. or higher, a Cu layer and an intermetallic layer having a melting point of 260° C. or higher. The structure of the joint buffers the stress generated by the secondary mounting and temperature cycle at the bond for the semiconductor element and the frame having a large difference in thermal expansion coefficient from each other.