Microstructure and performance evolution of SnPbSb solder joint under γ-ray irradiation and thermal cycling

The requirements of miniaturization and light-weighting in the manufacture of satellite have placed much emphasis on the property of its electronic materials. To comprehend the reliability evolution of solder joint in electronic components exposed to cosmic environment, the effect of γ-ray irradiation and thermal cycling on the microstructure and performance of SnPbSb solder joints was studied. The results indicated that micro-voids and micro-cracks formed in solder matrix and the mechanical property of solder joint was decreased with the increasing irradiation time, while the thickness of intermetallic compound layer (IML) in solder joints was hardly changed. Moreover, these micro-voids and micro-cracks partly vanished during the thermal cycling process due to the migration of atoms, but the thickness of IML was greatly increased which caused the further decrease of the mechanical property of solder joint. Fracture analysis indicated that the effect of irradiation and/or thermal cycling on the fracture type of solder joint was inconspicuous, but the ductility was slightly changed in different conditions.