High Energy Impact Resistance of Sb-Sn Lead-Free SMT Joint

It is believed that lead-free solders will replace conventional lead-tin solders in the electronic interconnection technology. For the lead-free solders, the soldering process should be compatible to the lead-tin solders using the surface mount technology but with different conditions such as high reflow temperature. In this paper, surface mount solder joints were thermally aged under various conditions to investigate for the growth of the intermetallic compound layer. Afterwards a shear test was carried out and decrease in the shear strength of the solder joint was found. A Hopkinson bar was employed to perform three-point bend test on the PCB. to impose dynamic loading on the solder joints. Four strain rates ranging from 3500 to 7300 s^-1 were used and the joint was completely destroyed when the strain rate is higher than 8600 s^-1. Finally, a shear test was performed to examine the change in the strength of the solder joints and it was found that the shear strength decreased with increasing strain rate.