Nickel phosphorus alloys as electrical contact material - Part I. Engineering properties of deposits from neutral ammoniacal bath.

Since a 40 year life is no longer an overall criterion for electrical contacts, there has been a relaxation in electrical requirements in some project designs which allows contact resistance (C.R.) values up to 50m-ohm. This is an area where non-precious metal deposits may be able to replace gold. One promising candidate is the nickel phosphorus alloy (Ni/P). A neutral pH (7.5-8.0) ammoniacal plating bath has been developed that produces low phosphorus content (2 atomic %) gray colored Ni/P deposits that have favorable low C.R. (2-7m-ohm) after exposure to several accelerated tests. The wear resistance and the internal stress of the Ni/P deposit are comparable to those of the typical hard gold plate used on plug-in type electrical connectors.