Thermally Stable Bonding of SiC Devices with Ceramic Substrates: Transient Liquid Phase Sintering Using Cu/Sn Powders

A high–temperature–resistant bond withstanding up to 415°C for SiC power devices is realized at 260°C with a Cu/Sn powder paste and an electroless nickel plated Si 3 N 4 /Cu circuit substrate. The bond was formed by using transient liquid phase sintering (TLPS). The bond strength tested at 300°C increases with increasing aging time at 300°C, from the original 40 MPa to 50 MPa after aging at 300°C for 200 h. This is attributed to phase transformation from Cu 6 Sn 5 formed during TLPS to Cu 3 Sn in the bond during aging. We observed an η–(Cu,Ni) 6.26 Sn 5 phase at the interface between the TLPS Cu–Sn bond and Ni(P) layer. The interface between the TLPS Cu–Sn bond and Si 3 N 4 /Cu/Ni(P)/Ag substrate exhibits very high stability, characterized by a very slow Ni(P) layer consumption rate and Ni 3 P growth rate. The TLPS Cu-Sn bond on a 5 μm-thick electroless plated nickel layer is expected to have a life time beyond 10 5 h during storage at 300°C.