Microstructure and aging resistance of the joints between SAC305 solder and thermoelectric materials with different diffusion barriers

The microstructure and aging resistance of SAC305 soldering joints with different diffusion barriers in thermoelectric application were investigated in this paper. Results indicate that the SACPNi joints (SAC305 solder and p-type (Bi,Sb)₂Te₃ thermoelectric materials with Ni diffusion barrier) exhibit more defects when increasing the aging temperature and time. However, there were less defects observed in the SACPSB joints (SAC305 solder and p-type (Bi,Sb)₂Te₃ thermoelectric materials with Sn-58Bi alloy diffusion barrier) when aging temperature and time increased. This result indicated that, for p-type (Bi,Sb)₂Te₃ thermoelectric materials, the diffusion barrier of hot-dipping Sn-58Bi alloy was more preferable than electroless plating nickel in the application of joining p-type thermoelectric materials and the Cu substrates with SAC305 solder.