Connector contacts: corrosion inhibiting surface treatments for gold-plated finishes

Studies were conducted to evaluate the performance of a large number of coatings, treatments, and platings for their effects on porous gold contacts under a variety of environmental stresses including corrosion resistance in a Class II FMG environment. The results showed that very few of these coatings gave satisfactory performance over a wide range of environmental conditions. Very few gave satisfactory corrosion inhibition. These included a number of materials previously reported to be useful for corrosion protection including gold flashed palladium-nickel. Several coatings were identified which did give long term corrosion protection and satisfactory performance at both high and low temperatures. Most notable among these were mixtures of a 6-ring polyphenylether and a microcrystalline wax in a volatile solvent. Low concentrations of these additions were shown to be important to avoid contact resistance increases at low temperatures and after thermal ageing. It was concluded that coatings can offer the best alternative for corrosion protection of porous gold. However, coatings must be matched to a knowledge of application conditions, since most coatings will not give satisfactory performance over a wide range of environmental conditions.