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 ch emical inertia of gold, it is widely admitted that adding an organic l ayer (polyphenyl esters, perfluorinated polyethers) to such surfaces m inimizes 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 f irst results an adhesion, friction and spectroscopic characteristics o f 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 (similar to 2 mu m). Two types of modification of the gold- finished plane by n-dodecanethiol are compared: direct immersion of th e surface as received, and immersion of the surface after UV-ozone exp osure. Results of the adhesion and friction experiments are correlated with detailed XPS surface analyses of the modified surfaces with n-do decanethiol. (C) 1998 John Whey & Sons, Ltd.