Wetting Kinetics and the Interfacial Interaction Behavior between Electroless Ni–Cu–P and Molten Solder

Abstract

Formation of intermetallic compounds and wetting kinetics between an electroless Ni–Cu–P deposit and molten solder were investigated. The microstructure and phase of the interface were investigated with the aid of scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Intermetallic compounds Ni₃Sn₄ and Ni₃Sn₂ were formed between Ni–Cu–P deposit and solder with Cu existing in the intermetallic layer. The contact angles of molten solder on a Ni–Cu–P deposit, measured with the sessile drop method, decrease with increasing temperature and time. The activation energy for wetting of molten solder on a Ni–Co–P deposit was estimated to be 193.7 kJ mol^-1.