Interfacial Reactions in Sn-xZn-Cu/Cu Couples during Soldering
The microstructure evolution and the growth behavior of intermetallic compounds (IMCs) at Sn-xZn-2Cu/Cu (x=6.5, 8.8, 10 and 12, wt%) interfaces during soldering were investigated. The results indicate that planar Cu5Zn8 layer is formed at each interface of Sn-8.8Zn-2Cu/Cu, Sn-10Zn- 2Cu/Cu and Sn-12Zn-2Cu/Cu couples for all soldering time. However, for Sn-6.5Zn-2Cu/Cu couple, it is Cu5Zn8 phase that formed at the interface within shorter soldering time (1 h and 4 h), but the interfacial reaction products become a double layer structure of Cu6Sn5 phase (near Cu substrate) and CuZn phase (near solder) for longer soldering time (25 h and 49 h). The thickness of IMC layers in all couples increases exponentially with the soldering time. It is also found that for the same soldering time, the thickness of IMC layers increases with increasing Zn content in the solder.
M.K. Lei, X.P. Zhu, K.W. Xu and B.S. Xu
N. Zhao et al., "Interfacial Reactions in Sn-xZn-Cu/Cu Couples during Soldering", Key Engineering Materials, Vols. 373-374, pp. 543-546, 2008