Tensile creep characteristics of Sn-3.5Ag-0.5Cu (SAC355) solder reinforced with nano-metric ZnO particles

Recently, nano-composite solders have been developed in the electronic packaging materials industry to improve the mechanical response of solder joints to be used in service under different conditions. In this study mechanical mixing has been used to disperse nano-metric ZnO particles in Sn-3.5Ag-0.5Cu (SAC355) solder at 420 °C for 2 h. In comparison with SAC355 solder, addition of nano-metric ZnO particles effectively suppressed the formation and restricted the volume fraction of the Ag3Sn and Cu6Sn5 intermetallic compound particles, lowering grain sizes and controlled the growth of β-Sn grains in the matrix. An improvement in tensile creep resistance of the reinforced SAC355 composite is noticed. This improvement seems to be due to its effect in structural refinement and makes the composite solder to display a large creep life time. The addition of nano-metric ZnO particles keeps the melting temperature nearly at the SAC355 level, indicating that the composite solder is fit for the existing soldering process.