Growth mechanism of Cu-Sn full IMC joints on polycrystalline and single crystal Cu substrate

Growth mechanisms of Cu-Sn IMC joints bonded at 300°C on polycrystalline and single crystal Cu substrates were investigated by Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD) technology. The results showed that the prism-type Cu₆Sn₅ grains formed on single crystal Cu substrate in the initial stage grew into the scallop-type Cu₆Sn₅ grains by grain rotation and merge mechanism with the proceeding of the bonding. In addition, the scallop-type Cu₆Sn₅ grains didn´t have preferred orientation. The columnar Cu₃Sn grains grew in clusters at the expense of Cu₆Sn₅ along direction of the adjacent Cu₆Sn₅ grains grain boundaries. The orientation of Cu₃Sn was unrelated to that of Cu or Cu₆Sn₅, but had preferred orientations of Cu₃Sn (100) parallel to the Cu substrate.