Pressureless Transient Liquid Phase Sintering Bonding of Sn-58Bi with Ni Particles for High-Temperature Packaging Applications

Transient liquid-phase sintering (TLPS) with nickel and Sn-58Bi was investigated for high-temperature packaging applications such as silicon carbide die attachment to direct bonded copper for a power module. Nickel was mixed with various ratios of Sn-58Bi (70, 80, and 90 wt%), which was then mixed with flux by a paste mixer to prevent oxidation and create a printable state. Thermal behaviors of three kinds of TLPS pastes were evaluated by a differential scanning calorimeter. The bonding temperature was 180, 200, and 220 °C for 90 min in air. The mechanical properties were examined by a bond tester. Shear strength increased with the temperature and Sn-58Bi weight ratio. The microstructures were observed by a scanning electron microscope. To investigate the atomic composition of the TLPS joints, an electron probe micro analyzer was used. Our results show that TLPS of nickel and Sn-58Bi is applicable for high-temperature packaging applications with reasonable cost, high re-melting temperature, and robust bonding.