Effects of Pb content on solidification behavior and microstructure on mixed solder alloy

The influence of different Pb content on solidification behavior, formation and evolution of microstructure in mixed solder alloy were investigated. It has been shown that the onset temperature of DSC cooling curve decreased with increasing of Pb content or decreasing of solder ball´s volume. When Pb content in solder alloy reached 21.90wt.%, the solidification behavior of mixed solder alloy was dominated by eutectic Sn-Pb alloy. The addition of Pb resulted in the coarsening of dentritic β-Sn in solder matrix significantly, and the addition of Pb resulted in the formation of a low melting temperature Sn-Ag-Pb ternary eutectic alloy easily.