Formation mechanism and orientation of Cu_3Sn grains in Cu-Sn intermetallic compound joints

摘要

The formation mechanism and orientation of Cu_3Sn grains in Cu-Sn intermetallic compound (IMC) joints formed on polycrystalline and (100), (111) single crystal Cu substrates at 300℃ were investigated. The results showed that when IMC joints were composed of Cu_3Sn and Cu_6Sn_5 phases, columnar Cu_3Sn grains grew in clusters at the expense of Cu_6Sn_5 phase. In addition, the Cu_3Sn grains growth direction was parallel to the Cu_6Sn_5 grain boundaries in the middle layer of the IMC joints. When the Cu_3Sn grains from the opposite sides contacted each other, grain growth stopped. Some small equiaxed Cu_3Sn grains were found both at the Cu/Cu_3Sn interfaces and in the Cu_3Sn contact areas in the middle of the joints. A preferred orientation of Cu_3Sn (100) crystal plane being parallel to the Cu substrate was found, which was unrelated to the orientation of Cu substrates.