Influence of ZnO nano-particles addition on thermal analysis, microstructure evolution and tensile behavior of Sn-5.0Â wt% Sb-0.5Â wt% Cu lead-free solder alloy

Sn-5 wt%Sb-0.5 wt%Cu (plain SSC505) and Sn-5 wt%Sb-0.5 wt%Cu-0.5 wt% ZnO (SSC-ZnO) composite solder alloys have been studied. The variation in thermal behavior, microstructure and tensile characteristics associated with mixing of 0.5 wt% ZnO nano-metric particles to plain SSC505 solder were investigated. A slight increment in the melting temperature [ΔTm=0.89 °C] was recorded using differential scanning calorimetry (DSC) after addition of ZnO. X-Ray diffraction (XRD) analysis confirmed the existence of β-Sn, SbSn and Cu6Sn5 intermetallic compounds (IMCs) beside some of ZnO planes in SSC-ZnO composite solder. Field emission scanning electronic microscope (FE-SEM) investigation of SSC-ZnO composite solder revealed a homogenous uniform distribution, size refinement of IMCs and β-Sn grains. Addition of ZnO nano-metric particles into the plain SSC505 enhanced the yield stress σYS by ~12% and improved the ultimate tensile strength σUTS by ~13%. In addition, adding ZnO nano-metric particles was found to be effective for reducing ductility by ~43% of the plain solder due to the refinement of β-Sn grains within SSC-ZnO composite solder.