Effect of Sb Addition on Microstructure and Shear Strength of Sn-3.0Ag-0.5Cu Solder Ball Joints

Abstract

The effect of a small amount of Sb addition to Sn-3.0Ag-0.5Cu (mass%) solder on microstructures and impact properties of the solder ball joint was investigated. Cross-sectional microstructural observation revealed that scalloped Cu6Sn5 is formed at the solder/Cu interface, and Cu3Sn is formed at the interface between Cu6Sn5 and Cu with aging. It was confirmed that the growth of the reaction layer is suppressed by the addition of Sb. Moreover, the result of the impact ball shear test showed that the decrease in impact properties with aging can be suppressed in Sn-3.0Ag-0.5Cu-1.5Sb (mass%). It was also suggested that the suppression of linear crack propagation at the Cu3Sn/Cu6Sn5 interface is effective to prevent the reduction of absorbed energy.