Although the research on Sn-Ag-Cu based high reliability solder alloy has been extensive, there is a lack of reports about the shear strength and fracture mode of the solder joints at different strain rates. In this research, the Sn-Ag-Cu solder pastes with different compositions, named SAC305 and Innolot, were printed on the Ni(P)/Au surface-finished substrates and reflowed to form BGA solder joints. The shear properties at different shear rates were tested using the DAGE 4000 HS bondtester, and the shear curves, shear strengths, and fracture energies were calculated and analyzed. The microstructure and fracture surface of the solder joint interface were characterized by metallographic microscope and scanning electron microscope (SEM). The results show that the difference in alloy compositions leads to a change in the thickness and distribution of the intermetallic compound layer at the solder joint interface. With an increase of the shear rate, the shear strengths of SAC305 and Innolot alloy solder joints increase accordingly in general, and the fracture mode of the solder joints shifts from the ductile fracture in the solder joint matrix to the brittle fracture of the intermetallic compound at the interface. Due to the strengthening effect caused by the addition of alloy elements, the shear strength of Innolot alloy is greatly improved, giving rise to the plastic damage. |