Effect of electron irradiation on microstructural evolution and mechanical properties of Sn3Ag0.5Cu solder joints

Abstract

Power electronic devices face harsh radiation environments in deep space exploration. It is significant to study the reliability of solder joints of electronic devices in radiation environments. The effect of electron irradiation on the microstructure and mechanical properties of Sn3Ag0.5Cu (SAC305) Ball Grid Array (BGA) solder joints was investigated in this work. The results show that the central position of the SAC305 solder joint surface was damaged after electron irradiation. Then the surface of the solder joints was remelted. The shear strength of solder joints increases as the electron irradiation dose rises. When the electron irradiation dose reaches 80 Mrad, the shear strength of the solder joint is enhanced by 8.62% compared with that of the unirradiated sample. After irradiation, the number of dimples on the fracture surface of solder joints increases and the depth of dimples decreases. Geant4 simulation results show that the surface of solder joint is subject to more severe electron impact than the inside of solder joint is. The interaction between electrons and solder joints is the primary reason for the surface remelting of solder joints.