| abstract |
A nickel-chromium alloy etching composition comprising sulfuric acid, a source of chloride ions, including hydrochloric acid or sodium, potassium or ammonium chloride, and a sulfur compound comprising a sulfur atom with an oxidation state between −2 to +5, such as thiosulfate, sulfide, sulfite, bisulfite, metabisulfite and phosphorus pentasulfide that can efficiently remove nickel-chromium alloy in the presence of copper circuits is disclosed. |