Interfacial Reaction between Sn and Cu-Ti Alloy (C1990HP)

Abstract

The interfacial reaction between pure tin and substrate with the composition of Cu-4.3 at% Ti (C1990HP) was investigated using the reaction couple technique from 240 °C until 270 °C in the range 0.5~4.0h. The SEM images show the Cu6Sn5 and small precipitated Ti2Sn3 phase formed at the Sn/C1990HP interface. In addition of Ti substantially increased the amount of intermetallic compound (IMC) at the interface which separated parts of Cu6Sn5 compounds with the inner region containing more Ti than the outer. The existence of Sn/C1990HP on the liquid/solid state reaction indicates that spalling occurred with changes in reaction time and temperature. With increased reaction temperature and time, the grain produced an abnormal condition resulting in Cu6Sn5 not accumulating at the interface and spalling into the solder in addition to grain ripening and an increase in total layer thickness. The hexagonal prism-shaped Cu6Sn5 phase is found on the top of the C1990HP substrate when the Cu6Sn5 layer detaches. The reaction phase formation, detachment, and split mechanisms are proposed in this study.