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Abstract
Conductive anodic filament (CAF) formation has been studied for a number of years, but the mechanism of its formation has not previously been defined. In 2002, Ready identified CAF as atacamite, Cu^sub 2^(OH)^sub 3^Cl. Electrochemical studies have shown that both CuCl and CuCl^sup -^^sub 2^ participate in the formation of Cu^sub 2^(OH)^sub 3^Cl, with the predominating species being CuCl. This paper proposes a mechanism for CAF formation based on x-ray photoelectron spectroscopy. The data show that CuCl is the precursor to the formation of Cu^sub 2^(OH)^sub 3^Cl in the presence of oxygen and water. Earlier, Meeker and Lu Valle had proposed that CAF failure is best represented by two competing reactions: the formation of a copper chloride corrosion compound (now identified as Cu^sub 2^(OH)^sub 3^Cl) and the formation of innocuous trapped chlorine compounds. Since no evidence of any trapped chloride compounds has been found, we propose that the formation of CAF is best represented by a single nonreversible reaction. [PUBLICATION ABSTRACT]