The effect of loading rate on the shear behavior of BGA solder joints under board-level

Abstract

This paper mainly studies the influence of loading rate on the shear mechanical properties of BGA solder joints, four kinds of solders (SAC305, SAC0307, SAC0307-0.07La and SAC0307-0.07La-0.05Ce) were prepared by means of experiment. The results show that the shear strength of the solder joints in the single board structure was increased with the increase of shear rate, but the shear strength of high-silver solder joints(SAC305) of board-level structure was increased first and then decreased with the increase of loading rate, while the shear strength of low-silver solder joints of board-level structure was increased with the increase of loading rate. In terms of plastic deformation, the fracture displacement of the solder joints in the two structures was both decreased with the increase of the loading rate. Especially, the fracture displacement of high-silver solder joints in the board-level structure decreases was the largest, but the low-silver solder joints with rare earth elements had a good impact load performance. It can be concluded from the fracture analysis that the fracture mode of high-silver solder joints in the board-level structure was changed from mixed mode of ductile and brittle fracture to brittle fracture with the increase of shear rate, while the low-silver solder joints was changed from ductile fracture to mixed-mode of ductile and brittle fracture. Furthermore, the fracture position of the solder joints with rare earth elements in the board-level structure was always in the bulk solder, and with the increase of loading rate, it would shift to the direction of the IMC but still arose in the bulk solder and the mode was still ductile fracture.