Investigation of Electromigration in Cu-Sn Interfaces under the Condition of High-Current Pulses

As electronic devices become more compact and power-dense, the reliability of solder joints, particularly those using lead-free solders such as $\mathbf{S n - 3. 5 A g}$, faces significant challenges due to electromigration (EM) and intermetallic compound (IMC) growth. This study investigates the effects of high-current pulses ($100-200 \mathrm{~A}$) on $\mathrm{Cu}-\mathrm{Sn}$ solder joints, focusing on the impact of Fe nanoparticle (NP)-doped flux on mitigating electromigration under accelerated conditions. Solder joints were subjected to pulsed current stressing at a sample temperature of approximately $75^{\circ} \mathrm{C}$, and the resulting microstructural changes were examined. Results showed significant IMC growth, particularly at the anode side of solder joints, with morphological transitions from scalloped to planar IMC structures. After pulsed current stressing, some joints exhibited IMC degradation at the cathode side. The influence of Fe NP doping on EM effects was less clear, with variability in the microstructural response observed across different solder bridges. These results demonstrate that pulsed high-current loading induces distinct microstructural changes and is a viable approach for studying accelerated electromigration.