Method for the manufacture of capacitive electronic discs
AssigneeRCA Corporation
InventorMarshal L. Whitehurst
Life of this patent
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Abstract
A method for passivating the surface of a recorded metal substrate in which the substrate is immersed for 5-30 minutes in a 35.degree. C.-85.degree. C. aqueous bath containing from about 5 to 30 g/l of an alkaline cleaner and from about 2.5 to 20 g/l of sodium dichromate, potassium dichromate, sodium permanganate, potassium permanganate, or mixtures thereof.
Claims11
The method for the passivation of the surface of a recording substrate comprised of a metal selected from the group consisting of copper, nickel or silver which comprises immersing said substrate into an aqueous mixture containing from about 5 to 30 g/l of a mild alkaline cleaner consisting essentially of trisodium phosphate, tetrasodium pyrophosphate or mixtures thereof and from about 2.5 to 20 g/l of an oxidizing agent selected from a group consisting of sodium dichromate, potassium dichromate, sodium permanganate, potassium permanganate, and mixtures thereof, said aqueous mixture being maintained at a temperature between 35.degree. C. and 85.degree. C. and the time of immersion being maintained between 5 and 30 minutes.
In the method for the manufacture of record stampers for use in the molding of capacitive electronic discs wherein a copper substrate is recorded with the information desired to be molded into the disc and is thereafter electroplated to provide a replica to be used as a master for the manufacture of the stampers, the improvement which comprises passivating the surface of the recorded copper substrate by immersing the substrate into an aqueous bath containing 5 to 30 g/l of a mild alkaline cleaner consisting essentially of trisodium phosphate, tetrasodium pyrophosphate or mixtures thereof and 2.5 to 20 g/l of an oxidizing agent selected from the group consisting of sodium dichromate, potassium dichromate, sodium permanganate, potassium permanganate, and mixtures thereof, said aqueous bath being maintained during time of immersion at a temperature between 35.degree. C. and 85.degree. C. and said time of immersion being maintained between 5 and 30 minutes.
Dependencies are inferred from the claim text.