ABSTRACT
This chapter explores finishes and coatings that are used on the contacts of separable electronic connectors. The terms “finishes” and “coatings” mean any material that is applied to a substrate. Thus, it includes electrolytic and electroless deposits, clad metals, fused metal layers, weldments, and materials from physical processes such as ion implantation and vacuum evaporation. Intrinsic porosity in electrodeposited coatings originates in occluded foreign materials such as oxide particles in the substrate surface, even after rigorous cleaning. Plating is much more deeply entrenched, having been practiced for some metals since long before the birth of the electronic connector. There are numerous captive and independent plating organizations that are supplied by many chemical and process equipment firms. Thermal diffusion has been studied in some detail for gold platings and, more recently, palladium-based finishes. Electroless plating involves the use of a chemical reducing agent in solution which provides the electrons for converting metal ions to the elemental form.
