| dc.description.abstract | Abstract
In modern high-power devices, the growing number of input/output ports demands complex heterogeneous material combinations. Effective thermal management during reflow is crucial to prevent chip damage. Therefore, low-temperature soldering processes provide a promising solution to minimize thermal stress on solder joints, common in high-temperature processes. The utilization of hybrid solders, specifically Sn-Ag-Cu (SAC) and Sn-Bi alloys, can significantly reduce processing temperatures, presenting a feasible alternative.
This study intends to investigate the electromigration phenomena in hybrid low-temperature solder joints (SAC305 ball/Sn-56.8Bi-1.0Ag-0.2Cu paste). samples were subjected to a current density of 0.8 and 1.0×103 A/cm² at 60°C, with current stress measured at intervals of 0, 5, 10, and 20 days to observe thermal migration effects. By examining the changes in the thickness and morphology of intermetallic compounds (IMCs) at the solder/Cu interfaces post-electrification and heating, it was found that IMC coarsening occurred at the SAC305/solder interface on the cathode and anode cold ends. Meanwhile, At the hot end of the SB102/Cu interface, IMC growth was inhibited by the accumulation of Bi atoms, which appeared as blocky Bi-rich phases, showing no significant changes. These changes were more significant under higher current densities compared to lower ones. Furthermore, due to thermal migration, Bi atoms diffused from the hot end towards the cold end, initially leading to the coarsening of Bi above the IMC interface at the hot end. These Bi atoms subsequently dispersed into the SAC305 forming small particles.
This research focuses on the size and distribution of Bi particles at the SAC305 ball and Sn-56.8Bi-1.0Ag-0.2Cu paste interface, as well as the IMC evolution at the cathode and anode ends of the composite solder system. We will discuss the impact of thermal migration and current application on the diffusion mechanisms, contributing to the reliability enhancement of composite soldering technology in future electronic manufacturing industries. | en_US |