한국주조공학회

Interfacial reaction and mechanical properties between Sn-Zn-X ternary al1oys(X : 3wt.%In, 4wt.%Bi) and Cu-substrate were studied. Cu/solder joints were subjected to aging treatments for up to 5odays to see interfacial reaction at 100°C and then were examined changes of microstructure and interfacial compound by optical microscopy, SEM and EDS. Cu/solder joints were aged to 3odays and then loaded to failure at cross head speed of 0.3 mm min" to measure tensile strength. According to the results of the solderability test, additions of In and Bi in the Sn-9wt.%Zn solder improve the wetting characteristics of the alloy and lower the melting temperature. Through the EDS and XRD analysis of Cu/Sn-9wt.%Zn solder joint, it was con~ eluded that the intermetallic compound was the 7-Cu5Zn3 phase. Cu-Zn intermetallics at Cufsolder interfaces played an important role in both the microstructure evolution and failure of solder joints. Cu/solder joint strength was decreased by aging treatment, and those phenomenon was closely related to the thickening of intermetallic layer at Cu/solder joints.