Copper Plating
Although electroless plating is typically associated with nickel plating, copper plating is another very common usage of that plating method. Used for more than three decades, electroless copper plating is utilized in a wide range of applications and industries including: industrial manufacturing, in which copper plating is utilized to add additional conductivity to low-conductance materials; electronics, where it is used as a less-expensive alternative to gold and silver on electrical devices such as printed circuit boards (PCBs); military, for the plating of ammunition such as frangible core bullets; power distribution, in which plating is used to provide better conductivity of power to commercial, industrial and residential buildings; and HVAC, used for plating of systems components such as bearings, pipe hooks and more. Copper plating can be used either as the final plating material or as a primary coating for secondary coatings such as tin, silver, gold and nickel.
There are four basic sub-processes that make up electroless copper plating: cleaning, activation, acceleration and deposition. In the cleaning phase, the copper is cleaned with a cleaner/conditioner (typically containing an alkaline solution) that functions to remove organics from the copper as well as to condition the copper for better uptake of the catalyst, or reactive chemical agent. The next phase is activation. In this phase, activation occurs as the result of a catalyst, typically something like hydrochloric acid or tin or sodium chloride. The copper is then immersed into a bath of the catalyst and other chemicals, such as palladium chloride. The acceleration phase is combined with the activation phase, and is an accelerant is also introduced into the bath. The accelerant is typically a chemical such as fluoboric acid or sulfuric acid with hydrazine. The accelerant functions to remove the remnants of the catalyst. The last phase of the process is the actual deposition of the copper. In this phase, there can be two types of electroless baths: a heavy deposition bath and a light deposition bath. While for heavy deposition baths, copper electrolytic plating may occur after further processing, light deposition baths require copper electrolytic plating to occur immediately afterwards.
