Copper stainproofing technique
AssigneeOlin Corporation
InventorsArvind Parthasarathi, Ned W. Polan
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Abstract
The present invention relates to a technique for improving the tarnish and oxidation resistance of copper and copper base alloy materials. The technique of the present invention involves immersing the copper or copper base alloy material in a dilute aqueous chromic acid-phosphoric acid solution. After emerging from the chromic acid-phosphoric acid solution, the copper or copper base alloy material is preferably rinsed with a dilute aqueous caustic solution and dried. Copper and copper base alloy materials treated in accordance with the present invention have particular utility in printed circuit applications.
Claims20
A process for imparting tarnish and oxidation resistance to copper and copper alloy foil material, said process comprising:
- applying a dilute aqueous chromic acid-phosphoric acid solution to said material, said solution having a concentration of chromic acid in the range of about 0.02 grams per liter to about 1 gram per liter and a concentration of phosphoric acid in the range of about 0.02 grams per liter to about 1 gram per liter.
A treatment for imparting improved tarnish and oxidation resistance to copper and copper alloy material, said treatment comprising a stainproofing solution containing from about 0.02 grams per liter to about 1 gram per liter of chromic acid, from about 0.02 grams per liter to about 1 gram per liter of phosphoric acid and the balance essentially water.
A process for imparting tarnish and oxidation resistance to copper and copper alloy foil material having a plurality of dendritic particles on at least one surface, said process comprising:
- applying a dilute aqueous chromic acid-phosphoric acid solution to said material having said plurality of dendritic particles, said solution having a concentration of chromic acid in the range of from about 0.02 grams per liter to about 1 gram per liter and a concentration of phosphoric acid in the range of from about 0.2 grams per liter to about 1 gram per liter,
- whereby application of said dilute aqueous chromic acid-phosphoric acid solution to said material does not significantly dissolve said dendritic particles.
Dependencies are inferred from the claim text.