Solid-Liquid Interdiffusion Bonding of Copper Using Ag-Sn Layered Films

抄録

Newly developed bonded materials and fabrication processes are expected to firmly bond copper leads to SiC chips for application in next generation power modules. Solid-liquid interdiffusion bonding of copper was performed using Ag-Sn layered films. Microstructural development and mechanical properties of bond layers were investigated. The bond layer grew at the thin film interfaces because of the solid-liquid interdiffusion. Cu₆Sn₅ and Ag₄Sn or Ag₃Sn phases were formed at the initial bonding stage, and subsequently, Cu₃Sn formed between the Cu₆Sn₅ and Cu as both bond time and temperature increased. Finally, the bond layer was primarily composed of Ag₄Sn and Cu₃Sn. The hardness and Young’s modulus of Ag₄Sn were much lower than those of Cu₃Sn. The growth of the Cu₃Sn layer that formed between Ag₄Sn and Cu could be limited by optimizing the design of the faying surface.