Effect of trace Al on growth rates of intermetallic compound layers between Sn-based solders and Cu substrate

► 1 wt% Al has been added into Sn, Sn-3.5Ag (SA) and Sn-3.8Ag-0.7Cu (SAC) solders. ► A significant reduction in IMC growth was observed in the SAC-1Al/Cu system. ► A layer of η2 (AlCu) to δ (Al2Cu3) IMC was found to evolve at the solder/Cu interface.