GB905047A - Chemical plating of copper and copper-lead alloys - Google Patents

Abstract

A chemical copper or copper-lead alloy plating bath comprises in an alkaline solution, preferably with a pH value more than 9, at least one complexing agent selected from the group consisting of soluble salts, e.g. sodium, of lactic, glycollic, mallic and citric acids; a copper or copper and lead ion source such as solutions of copper chloride, nitrate, acetate or sulphate, or with lead oxide, basic carbonate, nitrate or acetate; and a reducing agent selected from the group consisting of formaldehyde, its linear polymers, e.g. paraformaldehyde, and complexes thereof; with or without a proteinaceous stabilizing agent selected from the group consisting of gelatine, egg albumin, casein, dextrin and agar agar. Preferably, the alkaline solution contains 15 to 40 g./l. of alkali metal hydroxide, e.g. NaOH, 50 to 200 g./l. of complexing agent, 10 to 40 g./l. of ion source, e.g. CuSO4.5H2O, and the equivalent of 50 to 200 ml./l. of 37% formalin for the reducing agent, with or without 0.05 to 1.0 g./l. of gelatine. Air or oxygen may be bubbled through the bath which may or may not be stirred and/or subjected to high-frequency vibrations. The bath is suitable for depositing copper or copper-lead alloy on to an etched steel base.