Interfacial reaction and mechanical reliability between Sn-3Ag-0.5Cu alloy and ultrathin-Ni(P)-type Au/Pd(P)/Ni(P)/Cu metallization pad

Abstract Recently, a Au/Pd(P)/Ni(P) surface finish with an ultrathin Ni(P) thickness ( x P)/Ni(P)/Cu metallization pad, where the thicknesses of Au/Pd( x P)/Ni(P) were 0.08 μm/0.13 μm/0.13 μm and x were 0 wt%, 1–2 wt%, and 4–6 wt%. We found that the growth morphologies of intermetallic compounds (IMCs) at the Sn-3Ag-0.5Cu/Au/Pd( x P)/Ni(P)/Cu joints strongly depended on x and reflow number. The shear resistance of the solder joints could be greatly enhanced by reducing x , especially for one reflow; however, this difference was nearly alleviated after multiple reflows. This investigation provided valuable information about the role of P in the Sn-3Ag-0.5Cu/Au/Pd(P)/Ni(P)/Cu reaction system and the strategy to enhance the solderability of the Au/Pd(P)/Ni(P) surface finish.