In-situ observation of fracture behavior of Sn-3.0Ag-0.5Cu lead-free solder during three-point bending tests in ESEM

The effect of microstructure and corrosion on fracture behavior of Sn-3.0Ag-0.5Cu (SAC305) solder alloy was in-situ studied at three-point bending test using environmental scanning electron microscopy (ESEM). The results showed that the microcracks initiated at the Sn boundaries in the β-Sn region for commercial SAC305 solder. For furnace-cooled SAC305 solder, cracks preferred to initiating and propagating along Sn boundaries and Sn/Ag3Sn interface. Ag3Sn plates were easily broken during the bending test. The fracture behavior was significantly affected by corrosion. The most vulnerable area to fracture is the corroded region of the specimen.