Aqueous alkanesulphonic acid solution for the deposition of copper

摘要

The invention relates to an aqueous alkanesulphonic acid solution, preferably a methanesulphonic acid solution containing copper salts for the electrolytic deposition of smooth copper coatings having a uniformly matt appearance and high flexural elongation (breaking elongation), which can be coated with strongly adhering resists, to circuit boards coppered (copper-plated) by means of said solution and to their fabrication. To achieve the required characteristics of the copper coatings, the copper plating baths are admixed with additional organic sulphur compounds other than alkanesulphonic acids and their copper salts. It was found that advantageous organic sulphur compounds included sulphonic acids, their salts or sulphates. The salts employed of the sulphonic acids are preferably the alkali metal, alkaline earth metal and ammonium sulphonates.