Effect of adding Ce on interfacial reactions between Sn-3.0Ag-0.5Cu solder and Cu substrate

Abstract

The formation and the growth of Cu-Sn intermetallic compound (IMC) layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu₆Sn₅ IMC is observed at the interface between solder and Cu substrate in all conditions. After aging for 120 h, the Cu₃Sn IMC is then obtained. With increasing aging time, the scalloped Cu₆Sn₅ structure changes to a plate structure. The Cu₃Sn film always forms with a relatively planar interface. By adding a small amount of the rare earth element Ce (only 0.1%, mass fraction) into the Sn-3.0Ag-0.5Cu solder alloy, the growth rate of the Cu-Sn IMC at the interface of solder alloy system is decreased. When the time exponent is approximately 0.5, the growth of the IMC layer is mainly controlled by a diffusion over the studied time range.

Keywords

intermetallic compound / interface / Sn-3.0Ag-0.5Cu solder / rare earth element