Effect of Pulse-Plated Nickel Barriers on Tin Whisker Growth for Pure Tin Solder Joints
We investigate the influence of pulse-plated Ni barriers, compared to direct current (DC)-plated Ni barriers, on the growth of Sn whiskers in laminated Cu/Ni/Sn samples. The results indicate that the pulse-plated Ni barriers exhibit much better resistance to Sn whisker growth than the DC-plated Ni barriers, i.e., when exposed to ambient of 60°C and 93% relative humidity (RH) for 40 days only a few small hillocks were observed as opposed to the long whiskers and large nodules of Sn for the DC-plated Ni barriers. The underlying mechanisms are addressed based on the texture characteristics of the plated Ni and Sn layers and the formation of intermetallic compounds.