Influence of Sb on the Performance and Interfacial Behavior of SnBiAg-xSb/Cu Solder Joints

In this work, SnBiAg-xSb solder alloys (where x = 0, 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, and 2.5 wt.%) were prepared by compression and annealing treatment following water cooling. The microstructure of the SnBiAg-xSb alloy became finer due to the addition of a small amount of Sb. When the Sb content exceeded 1.0 wt.%, the effect of grain refinement decreased, and the grain gradually became coarser with the addition of Sb. As the Sb content increased, the tensile strength of SnBiAg-xSb solder alloys gradually increased while elongation decreased, which was attributed to the solution strengthening of Sb and subsequent microstructural changes. SnBiAg-0.5Sb showed the best elongation at break, reaching a value of 119.12%. Sb increased the starting temperature of the solder during solidification and cooling, expanding the range of the mushy temperature zone. The addition of a small quantity of Sb had a minimal effect on the solder’s wettability. The bonding performance of SnBiAg-xSb solder joints before and after aging was studied, and it was found that SnBiAg-2.0Sb solder joints had the strongest bonding strength.