Experiment and Numerical Simulation of Shear Creep of Cu/SAC305/Cu Microscale Solder Joints

Based on the dynamic mechanical analyzer（DMA Q800, TA-Instruments）, the shear creep of Cu/Sn-3.0Ag-0.5Cu/Cu lead-free microscale solder joints with a diameter of 400 μm and a height of 250 μm was studied under constant stress（10 MPa） and different temperatures（100 ℃, 110 ℃, 120 ℃）, and a constant temperature（100 ℃） under different stresses（8 MPa, 10 MPa, 12 MPa）. Then, the finite element analysis software ABAQUS was adopted to simulate the shear creep under the same conditions as the experiment. The experiment results show that the activation energy（Q） of SAC305 solder joint is 114.5 kJ/mol under the shear stress of 10 MPa, and the shear creep stress index n is 6.12 at 100 ℃. The simulation results show that the activation energy is 105.49 kJ/mol under 10 MPa, and the shear creep stress index is 6.67 at 100 ℃.According to the creep activation energy and creep stress index, the shear creep mechanism is mainly the lattice diffusion mechanism. In addition, the shear creep fracture pass through the solder matrix and close to the SAC305 solder/IMC interface region, and the fracture is typical ductile fracture.