Electromigration

Cross-scale simulation of diffusion-induced void evolution under electromigration and random vibration reliability of Sn58Bi solder joints

With the continuous miniaturization and increasing power density of electronic packaging, solder joints are exposed to higher current densities and more severe thermal-electrical coupling conditions, which accelerate electromigration-induced void formation. Once formed, these void defects can further amplify stress concentration under random vibration loading, significantly increasing the risk of premature failure in electronic interconnections. In this study, a cross-scale simulation method combining phase-field simulation and finite element modeling (FEM) simulation was adopted. First, phase-field simulation of the void evolution inside the solder joints under the thermal-electrical coupling at the mesoscopic scale was carried out, and the atomic diffusion driven by chemical potential gradient and electric field was taken into consideration. Then the obtained solder joint models containing the voids were imported into the finite element analysis software for the macroscale prediction of stress and strain distribution under random vibration. The research results showed that under the influence of current, the voids formed at the corner of the current inlet and expanded along the interface between solder and copper pad. Random vibration simulation results demonstrated that void-containing solder joints generate a maximum equivalent stress of 68.7 MPa and a maximum tangential strain of 4.37×10 -4 . These values represent 2.7-fold and 1.6-fold increases respectively compared to void-free solder joints. In addition, the size effect significantly reduces solder joint reliability, with diminished joint dimensions directly correlating to decreased reliability.