Adhesion properties and surface analyses of monolayers of n-dodecanethiol self-assembled on galvanic gold

Galvanic gold is an important protective final layer in most low‐level electrical contacts for high‐reliability applications. Despite the chemical inertia of gold, it is widely admitted that adding an organic layer (polyphenyl esters, perfluorinated polyethers) to such surfaces minimizes friction and wear during insertion and extraction operations, as well as prevents corrosion. In a recently published work on nickel surfaces we have shown that a single monolayer of mercaptan exhibits outstanding antifriction and antiwear properties. Here we report the first results an adhesion, friction and spectroscopic characteristics of n‐dodecanethiol monolayers built on galvanic gold. Based on several works showing the relation between adhesion and friction, we study two parameters: the static friction coefficient at the onset of sliding, and the dynamic friction coefficient during motion. The system used to conduct the study is a ball (CuBe)–plane (CuZn) set‐up where both the ball and the underlying metallic plane have a final electrodeposited gold layer (∽2 μm). Two types of modification of the gold‐finished plane by n‐dodecanethiol are compared: direct immersion of the surface as received, and immersion of the surface after UV–ozone exposure. Results of the adhesion and friction experiments are correlated with detailed XPS surface analyses of the modified surfaces with n‐dodecanethiol. © 1998 John Wiley & Sons, Ltd.