FAQ

Q: Specifing Nickel Underplate

A: Question: Can you indicate what Ni-plating is most efficient for this system with regard to roughness, ductility and wear resistance of the contact. For the moment we are discussing about bright or semi-bright Ni (1-2 microns), but we don’t know all about the influences of brighteners on the mentioned aspects.

Answer: Electroplated gold coatings for electrical contact applications should always be applied over a sulfamate nickel underplate. A sulfamate nickel underplate provides a diffusion barrier that will inhibit the diffusion of base metal constituents (i.e. copper, zinc, etc.) to the surface of the gold where they can oxidize. A sulfamate nickel underplate will also serve as a mechanical support for the gold coating and increase it’s durability. The thickness of this sulfamate nickel underplate should be at least 1.3 micros (50 micro inches). Bright nickel deposits, while they are generally harder than sulfamate nickel, can contain relatively large amounts of co-deposited organic materials that can be detrimental to other function requirements of electrical contacts such as solderability. Generally, bright nickel is not used as an underplate in connector applications.