An investigation on the performance of gold layer based cyanide-free HAuCl4 electroplating process under different power conditions

Abstract

Gold electroplating experiment was carried out by cyanide-free chloroauric acid-based (HAuCl4-based) electroplating process in this paper. Smooth, uniform and golden thick gold layers can all be obtained after 6 h under DC, UD and PR condition. With the changing of power, the macroscopic characteristics and structure of gold layers change obviously. Sample has the best luster under PR condition. SEM images show that microstructure of gold layers vary at different power condition. AFM images show that gold layer under PR condition has the lowest surface roughness. After polishing, samples obtained under DC and UD condition have different densities of pores, while the pores are almost invisible under PR condition. XRD tests show under DC power supply, sample has no obvious orientation. The texture coefficient of (220) crystal plane of gold plating under UD condition can reach to 62.5%, and that of (200) crystal plane under PR condition can reach up to 98.9%. Texture of each sample calculated by XRD data can be verified by EBSD. Gold layer under PR condition has the highest hardness, which can reach up to 98.05 × 10−2 GPa. Gold layer under PR condition possess a number of advantages over the other powers. For pure hard gold, HAuCl4-based baths is a suitable alternative to cyanide-based baths.