Etching objects made of copper and a less noble metal, especially brass

摘要

Objects made of copper and brass are etched with aqueous persulfate solutions containing organic complex formers together with (in)organic sulfur compounds and/or nitrogen compounds to inhibit the over-etching of brass and increase the current yield in subsequent regeneration of persulfate by anodic oxidation. A process for etching objects made of copper and a less noble metal, especially copper and brass, with subsequent regeneration of the etching solution comprises etching in an aqueous persulfate-containing solution followed by cathodic reduction to precipitate the dissolved copper and anodic oxidation to convert sulfate back into persulfate, using an etching solution which contains organic or inorganic sulfur compounds and/or organic or inorganic sulfur-free nitrogen compounds to increase the current yield in anodic oxidation. The concentration of the additive(s) is increased so that a higher current yield is accompanied by a decreased rate of erosion of the less noble metal during etching, and the etching solution also contains an organic complex former.