Effects of aging time on interfacial fracture behaviors of Sn3.5Ag0.5Cu/Cu joints

The effects of the intermetallic compound (IMC) microstructure on the tensile strength and the fracture behavior of Sn3.5Ag0.5Cu/Cu solder joints are investigated. The soldered samples are isothermally aged at 150°C for 0, 72, 288, 500 hours, respectively, and then are tested at the strain rate of 2×10^-4 s^-1 at room temperature in air. The experimental results show that with the increase of the isothermal aging time, the IMC layer thickness increases, and the roughness of the solder/IMC interface decreases. The tensile strength of the solder joint decreases with either increasing IMC thickness or increasing solder/IMC interfacial roughness, and the fracture mode migrates from ductile fracture in bulk solder to brittle fracture in the IMC layer with increasing aging time.