Optimal design of SnAgCu-CNT solder lap-shear specimen under thermal cycles with FEM

In this study, multi-walled carbon nanotubes were successfully incorporated into Sn95.5Ag3.8CuO.7 solder to synthesize novel lead-free composite solders. The paper presents a numerical approach to track the shear stress and creep strain behaviors at the solder joint in lap-shear specimen subject to thermal process. Some notches with different sizes and shapes are designed on the substrate next to the solder. In the investigation, using FEM, the distribution of shear stress and creep strain is simulated and compared under the same conditions but different notch designs. The analytical results show that the distribution of shear stress and creep strain embodies obvious periodicity. The shear stress varies nearly in-phase with the temperature while creep strain does out of phase with temperature. The triangular and round notches are helpful to uniform the range of shear strain. In triangular and round notch designs, notch size does little to affect the distribution of creep strain.