“…During the soldering process, this Ni(P) metallization reacts with the solder (usually a Sn-based alloy), forming an interfacial layer of intermetallic phases, comprising, e.g., Ni 3 Sn 4 1,2 if no Cu is involved, (Cu,Ni) 6 Sn 5 (for Cu contents of 0.7 wt.% or more in the solder 3,4 ), and (Cu,Ni) 3 Sn 4 (for 0.5 3 or 0.2 4 wt.% Cu in the solder), or even both (for 0.5 wt.% Cu 4 ). The original Ni(P) layer will also start to crystallize due to Ni depletion and formation of Ni 3 P. 1,3 Thus, depending on the concentration of P in the layer and the composition of the solder, different IMC layers can be formed during soldering.…”