Intermetallic compound transformation and mechanical strength of Ni-Sn transient liquid phase sinter-bonded joints in an extreme high-temperature environment

In this study, the transformation of the intermetallic phase and high-temperature durability of the 30Ni-70Sn (wt%) transient liquid phase sinter-bonded (TLPS) joints at an extremely high temperature of 500 degrees C were investigated. After a heat treatment at 500 degrees C for 50 h, all remaining Ni particles were consumed to form the Ni-rich Ni3Sn intermetallic phase. Compared to the as-bonded joint, the bond strength of the TLPS joints aged at 500 degrees C increased by approximately 2-3 times; the joints had superior mechanical strength values. All Ni3Sn intermetallic compound joints without remaining Ni particles enhanced joint integrity and improved the mechanical strength of the TLPS joints. The Ni-Sn TLPS bonded joints had metallurgically stable interfacial microstructures. We propose that micro-sized Ni-Sn TLPS paste will be a promising alternative to expensive Au-based hard solder alloys and Ag sinter pastes for high-temperature power electronic applications.