논문 : Sn-3.5wt.%Ag- 1wt.%Zn 땜납과 Cu 기판간의 미세조직 및 계면반응

This study examined the effects of adding Zn to Sn-3.5Ag solder on the microstructure changes and behavior of interface reaction of the solder joint with Cu substrate. The solder/Cu joints were examined with microscope to observe the characteristics of microstructure changes and interfacial reaction layer with aging treatment for up to 120 days at 150℃. Results of the microstructure changes showed that the microstructures were coarsened with aging treatment, while adding 1%Zn suppresses coarsening microstructures. The Sn-3.5Ag/Cu had a fast growth rate of the reaction layer in comparison with the Sn-3.5Ag-1Zn at the aging temperature of 150℃. Through the SEM/EDS analysis of solder joint, it was proved that intermetallic layer was Cu_6Sn_5 phase and aged specimens showed that intermetallic layer grew in proportion to t^1/2, and the precipitate of Ag_6Sn occur to both inner layer and interface of layer and solder. In case of Zn-containing composite solder, Cu_6Sn_5 phase formed at the side of substrate and Cu-Zn-Sn phase formed at the other side in double layer. It seems that Cu-Zn-Sn phase formed at solder side did a roll of banrier to suppress the growth of the Cu_6Sn_5 layer during the aging treatment.