Method of generating precious metal-reducing patterns

USRE29015E · kind E · reissue

Assignee

• Western Electric Company, Inc. · US

Inventors

• Michael Anthony De Angelo · Ewing Township, US
• Donald J. Sharp · Albuquerque, US

Key dates

• Filing date: Dec 4, 1975
• Grant date: Oct 26, 1976
• Expiry date: Dec 4, 1995

Classification

• Technology area (CPC —): General

Abstract

A pattern capable of reducing thereon a precious metal is generated on a suitable substrate by first coating selected portions of the substrate with a solution, called a photopromoter, which contains a metal salt. The metal salt possesses two characteristics: PA1 (a) the oxidation state of the salt (i.e., of the metal ion) is alterable (either increasable or decreasable) by exposure of the salt to radiation of the proper wavelength; and PA1 (b) in either the original or the altered oxidation state (but not in both states) the salt is capable of reducing a precious metal, e.g., a metal of the platinum group such as palladium, platinum or rhodium, from a salt thereof. The photopromoter-coated substrate is next selectively exposed to the proper wavelength radiation to produce a pattern of the photopromoter salt capable of reducing the precious metal. The remainder of the salt is incapable of reducing the precious metal. The pattern may then be exposed to a solution containing a salt of the precious metal to reduce thereon the precious metal. Ultimately, the precious metal pattern may be used to reduce electrolessly a metal, such as copper, to produce a metallic pattern, such as an ele…