Effect of gamma-ray irradiation on microstructure and mechanical property of Sn63Pb37 solder joints

Abstract

In order to meet the reliability requirement of solder joints for future small satellite, the effect of γ-ray irradiation on the microstructure and mechanical property of Sn63Pb37 solder joints was investigated by scanning electron microscope observation and mechanical testing. The results showed that γ-ray irradiation possessed few influence on the thickness and morphology of intermetallic compound layer of Sn63Pb37/Cu. But the mechanical properties of solder joints were reduced with micro-voids and micro-cracks appearing in Pb-based solid solution during irradiation process. Energetic electrons created by γ-ray through Compton Effect, generated dislocated atoms which eventually resulted in the formation of microscopic defects and the decrement of mechanical property. After 960 h γ-ray irradiation at the dose rate of 0.25 Gy(Si)/s, the shear force of Sn63Pb37 solder joints was decreased by 11.47%. Compared with as-soldered joint, the ductility of irradiated solder joints was reduced with more unobvious shear dimples and lower impact toughness.