US Patent 10260000 Etching of plastic using acidic solutions containing trivalent manganese

A method of preparing a solution capable of etching a platable plastic. The method comprises the steps of: (a) providing an electrolyte comprising a solution of manganese(II) in a solution of 9 to 15 molar sulfuric acid or phosphoric acid to an electrolytic cell; (b) applying a current to the electrolytic cell, wherein the electrolytic cell comprises an anode and a cathode; and (c) oxidizing the electrolyte to form manganese(III) ions, wherein the manganese(III) ions form a metastable sulfate complex. Thereafter, a platable plastic may be immersed in the metastable sulfate complex for a period of time to etch the platable substrate prior to subsequent plating steps.