Improving the performance of silver coating deposited on copper through corrosion inhibitors

Abstract

Immersion silver plating is an important surface finishing technique in the integrate circuit industry. However, it often results in silver coatings with poor compactness and adhesion due to the significant difference in potentials between silver and copper. The corrosion inhibitors of copper, rather than complexing agents of silver ions, were used to improve the immersion plated silver coating performance on copper. It was found the combined use of benzotriazole and imidazole could regulate the erosion rate of the copper substrate and improve the quality of the silver coating. The effects of different inhibitors concentrations on surface morphology, elemental composition, corrosion resistance, hardness, and conductivity of the silver coating were studied. The results indicated the optimal concentration of the combined inhibitors was 0.058 mol∙L-1, which enhanced the compactness, crystallinity, and overall performance of the silver coating by passivating the copper surface and regulating the silver deposition process.