Adhesion coefficients of plated contact materials

Adhesion (sticking) of sealed contacts may cause serious problems in certain applications. Adhesion occurs when two surfaces are pressed together under a purely normal load or under combined normal and shear forces. An experimental apparatus has been designed and constructed so that the coefficient of adhesion can be measured accurately in a controllable and reproducible manner. This paper reports measurements of adhesion coefficients σ of different plated materials in sealed contact applications. The values of σ are reproducible within 3%. It has been found that ruthenium- and rhodium-plated contacts and soft diffused gold contacts yield the minimum coefficient of adhesion.