An in-situ experimental and simulation study on the electromigration behavior of SAC305 solder joints

As the current density increases in electronic devices, electromigration has become a significant factor affecting the reliability of solder joints. In this study, the electromigration characteristics of Sn3.0Ag0.5Cu (SAC305) solder joints were investigated with in-situ experiments and finite element simulation methods. As the duration of current flow rose from 0 to 100 h, the thickness of the intermetallic compound (IMC) at the anode of solder joint S1 increased from 6.86 mu m to 26.55 mu m, and the thickness of the IMC at the cathode decreased from 5.22 mu m to 0.75 mu m. The thickness of the IMC at the anode of solder joint S3 increased from 4.91 mu m to 23 mu m, and the thickness of the IMC at the cathode decreased from 6.83 mu m to 0.58 mu m. The upper side of the solder point S2 is connected to the Cu wire through which current flows, and electromigration occurs in the horizontal direction, resulting in the formation of a void in the upper right corner of the solder point. The simulation results show that current concentration occur at the corners of solder joints S1 and S3, resulting in an increase of the current density in this area. When electrons move horizontally from the upper surface of the solder joint S2, the solder joint atoms migrate from one side to the other and form voids. The voids further increase the local current density around them and intensifies electromigration in this region. This research is of significance for the design of high-reliability packaging structure.