Effect of electric current on fracture and constitutive behavior of SN-Ag-Cu solder joints

The effect of electric current density on the tensile fracture property of 96.5SN-3.0Ag-0.5Cu (in wt.%) solder joints was studied. Experimental results indicate that the mechanical property was profoundly affected by the electric current due to electromigration. The variation of ductility, plasticity and rupture strain was revealed by the stress-strain curves obtained from experimental studies. Based on the mechanism of elastic-plasticity and damage, a unified creep-plastic-damage constitutive model with variables of plastic strain, damage threshold and inelastic dissipation was developed. The relationship of damage parameters and electric current time has been determined from experimental and numerical analysis. In general, the proposed model can predict mechanical behaviors of solder under current density with reasonable accuracy.