The influence of imposed electric current on the tensile fracture behavior of micro-scale Cu/Sn-3.0Ag-0.5Cu/Cu solder joints

The fracture behavior of microscale lead-free Sn-3.0Ag-0.5Cu solder joints under electrotensile load was characterized, in comparison with those under pure tensile load. Experimental results show that under electrotensile load the stress-strain and strain-time curves of joints exhibit three distinct stages, i.e., the fast deformation stage at the beginning of loading, linear deformation stage and the accelerating fracture stage. No significant difference in strain feature between the electrotensile loaded joint and pure tensile loaded joint was observed. The solder joints under electrotensile loading and tensile loading exhibit the same fracture mechanism at the same thickness-to-diameter ratio of joints, while the fracture strength of solder joints under electrotensile load is decreased greatly compared with that under pure tensile load, even lower than that of the bulk solder. Moreover, the orientation of β-Sn grains may tend to rearrange along the direction of current stressing under electrotensile loading.