Sequential interfacial reactions of SAC305 solder joints with thin ENEPIG surface finishes

摘要

Sequential interfacial reactions of Sn-3.0Ag-0.5Cu solder on a new multilayer metallization, ENEPIG (electroless nickel-electroless palladium-immersion gold) with a 0.1-mu m-thin Ni(P) layer (thin-ENEPIG), during reflowing were evaluated in this study. After 20-second reflow process, layer-shaped (Au,Cu)Sn-4 intermetallic compounds formed at the interface, and thin Ni and Pd layers underneath the Au layer remained unreacted on the polycrystalline Cu substrate. On the other hand, Au, Pd, and Ni tri-layers in the thin ENEPIG layer were exhausted and (Cu, Ni)(6)Sn-5 intermetallic compounds formed at the interface after reflowing for 30 seconds.