Dynamic mechanical properties and parameters of constitutive model for lead-free solder

The dynamic mechanical properties of Sn-Ag lead-free solders have been studied by means of a split Hopkinson pressure bar (SHPB) at various strain rates. Tests were conducted at room temperature and under uniaxial compressive conditions. It is shown that the Sn-Ag lead-free solders are viscoplastic materials, which are sensitive to the strain rate at higher strain rate. It is found that the materials´ dynamic yield stress largely falls into a linear relation to the strain rate in logarithm scales. Phenomenological dynamic constitutive equation was then established following Cowper-Symonds model. The dynamic mechanical prosperities and effects of strain-rate of lead-free solder discussed explain that Sn-Ag solder is attractive to the electronic industry.