Session 2: Metal Finishing: Past, Present, and Future
Understanding the benefits achieved by using synthetically manufactured copper & silver salts for the cyanide free electroplating of busbars.
General Surface Finishing
Usage of copper is very much common to the manufacturers of busbars because of their conductive and mechanical properties. To reduce the cost user’s in this subcontinent have shifted to feasible, substitute aluminum as base material. Bot copper & aluminum with time gets oxidized. Oxidized layer on metal base is not as conductive as the bare metal. As metal oxidizes it will slowly become less conductive and eventually begin to weaken, flake and fall apart.
Electroplating of busbars helps to keep cleaner contact surface by preventing corrosion. The traditional electroplating processes used in this application are as under:
• Copper plating
• Silver plating
• Tin plating
Copper & Silver are plated extensively plated using established cyanide containing baths. But, increased personal safety and health consciousness coupled recent ROHS, OSHA, EPA directives have led to more interest towards the usage of cyanide free electrolytes. Cyanide free chemistries for both copper & silver plating are reported by researchers since years, but these processes could not eventually got commercially accepted due to lower tolerance towards metallic impurities, poor colour stability (turning into blackish yellow tint on storage of the plated silver deposit) & also, inadequate deposit adhesion. Processes are developed & commercialized to produce finer grained copper & silver deposits utilizing cyanide free chemistries. Tolerance towards impurities of such silver plating proposition is found to be improved significantly. In addition silver deposit from this chemistry is brighter in appearance. Main differentiators for these processes are the copper & silver complexes which are synthetically manufactured utilizing copper & silver salts for respective systems. Analytical findings e.g. coating morphology, deposit hardness, internal stress, adhesion tests, etc. of such innovative propositions for both cyanide free alkaline copper & silver-plating processes are presented in this paper.