Striking Bath of Copper Sulfite Complex for Copper Deposition

In recent years, the development of non-cyanide baths for electroplating of various metals has been demanded for the purpose of preventing water pollution in our country. However, since no suitable striking baths for copper have been found, cyanide baths have still been employed till now. For the settlement of this problem, many kinds of inorganic and organic copper complexes were examined for the use in the striking bath with respect to the adhesion of deposit film, the price and toxicity of the compound, easy treatment of the waste liquor, etc. As a result, sodium sulfitocuprate was selected among them. Its molecular formula was determined at first, and then, various conditions of electroplating were investigated on a bath containing that compound as the principal component. This striking bath was slightly deficient in stability; but a good copper deposit was formed on the steel surface under considerably low current densities.