NON-SMUTTING ACID ETCHANT RINSE FOR ALUMINUM CONTAINING AT LEAST 20PPM OF FERRIC ION

摘要

Abstract of the DisclosureProblems with previously known aqueous acidic rinsingsolutions for aluminum after shaping while using surfacelubricants are avoided by use of a solution comprisingwater and (A) orthophosphoric acid in an amount to give astoichiometric equivalent of 3.0 to 50 g/L as PO4-3, (B)an aluminum ion sequestrant component in an amount of 0.01to 10.0 g/L; and (C) 20 to 170 ppm of ferric ion.Preferably the solution also contains 0.1 to 1.0 g/L ofH2O2, NO2-1 ions, or a mixture thereof to reoxidize ferrousions formed by reduction of ferric ions during use of thesolution and thus maintain the concentration of ferric ionsabove 20 ppm at all times. The solution may also containsurfactant and up to 10 g/L of dissolved aluminum ions.