Wetting kinetics and wettability enhancement of Pd added electrolytic Ni surface with molten Sn-3.0Ag-0.5Cu solder

Sequential wetting reactions of molten Sn-3.0Ag-0.5Cu solder on electrolytic Ni and Ni-xPd (x=4 and 10 wt%) surface finish were investigated using the in situ monitoring of force-time measurement via the wetting balance. Significantly different kinetics was documented and the correlation between the characteristic wetting stages and the formation of interfacial intermetallic compounds were addressed and discussed. Besides, the addition of Pd tends to decrease the wetting time while increase the wetting force during soldering reaction. The wetting enhancement may be attributed to the drop of activation energy as well as interfacial tension and the change in microstructure of intermetallic compounds between solder and substrates. (C) 2012 Elsevier B.V. All rights reserved.