Electromigration behavior of the Cu/Au/SnAgCu/Cu solder combination

The electromigration behavior of the Cu/Au/SnAgCu/Cu combination was investigated under 10³ A/cm² of current stressing at ambient temperature. The Au layer, when it acts as a cathode, was consumed continuously, and no significant compound was found at the interface. Meanwhile, Cu₆Sn₅ was formed at the anodic Cu layer, and the thickness of the compound increased with increasing time. The Au atoms were found to be trapped in Cu₆Sn₅ within the solder matrix. The AuSn₄ compound precipitated while attaching to Cu₆Sn₅ at the Cu₆Sn₅/solder interface. The thermomigration effect was found to be insignificant in this work as no obvious reaction occurred at the cathode/anode sides or in the solder matrix without current stressing.