The Effect of a Brightener on the Initial Electrocrystallization Stage of Gold

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Abstract
The effect of the addition of a brightener, trivalent arsenic ions, to a gold-sulphite plating solution on the structure and the internal stress was investigated. The addition caused an increase in the number and a decrease in the lateral size of the crystallites which constituted the initial stage of epitaxial electrocrystallization. This effect is explained in terms of the additive acting as a nucleating agent as well as blocking lateral growth. The additive affected the internal stress because the smaller lateral size of the crystallites resulted in a higher tensile value of the intrinsic stress when they coalesced to form a deposit layer. The higher coalescence stress was superimposed on an extrinsic one resulting from the mismatch of the substrate and deposit crystal lattices. The extrinsic stress was compressive in gold deposits on copper and slightly tensile when a silver substrate was employed.