Interfacial Intermetallic Compounds of Bi2Te3/Cu joint using SAC305 solder and nano-Ag paste

Sn-3Ag-0.5Cu(SAC305) solder and nano-Ag paste were used as bonding materials to combine Bi2Te3-based thermoelectric materials with Cu or ENIG-Cu electrodes. To investigate the thermal stability of the Bi2Te3/bonding material interface, heat treatment was performed at 200 °C for 0, 100, 200, and 500 h. Bi2Te3/bonding material interface properties were analyzed through compositional identification and morphological observation. Intermetallic compounds (IMCs) were formed under SAC305 and nano-Ag paste applied conditions. The IMC morphology change was observed with annealing time. The IMCs phase composition was confirmed by qualitative analysis. SnTe IMC was confirmed at the interface where SAC305 was applied, and Ag2Te IMC was confirmed at the interface where nano-Ag paste was applied. Also, the fracture mode was checked by shear test. This study confirms the effect of IMC composition and morphology on bond strength with increasing annealing time.