Cu–Sn and Ni–Sn transient liquid phase bonding for die-attach technology applications in high-temperature power electronics packaging

Power electronics modules in electric vehicles and hybrid electric vehicles, particularly those containing next-generation power semiconductor devices such as silicon carbide and gallium nitride are operated at high temperatures exceeding 200 °C. Consequently, the reliability requirements for such modules have become highly stringent and new packaging materials and technologies are required to meet the demands of power electronic modules. Some good candidates for high temperature applications include high-temperature solders such as Au–20Sn, Ag or Cu sinter pastes, and transient liquid phase (TLP) bonding materials. In particular, the TLP bonding technology is suitable for use in high temperature environments owing to its low cost and simplicity of the bonding process. In this study, the feasibility of Cu–Sn and Ni–Sn TLP bonding technologies as die-attach methods for power electronics packaging applications is examined. The results of the study indicate that the Cu–Sn and Ni–Sn TLP bonding processes transform the joints fully into Cu₆Sn₅/Cu₃Sn and Ni₃Sn₄ intermetallic compounds (IMCs), respectively. Further, the mechanical strength and reliability of the two TLP bonding joints are reduced owing to the formation of brittle IMCs.