Fry's Metals, Inc.

Alpha Metals, Inc.

Other

Enthone Incorporated

Peter Thomas McGrath

Andrew McIntosh Soutar

Eric Yakobson

Abayomi I Owei

Andrew David Price

Saeed Sardar

Abayomi Owei

A process used during manufacture of printed circuit boards comprises protecting metal pads and/or through-holes to provide a tarnish-resistant and solderable coating. In the method, the pads and/or through-holes are bright-etched, metal plated, preferably by an immersion process, and treated with a tarnish inhibitor. The tarnish inhibitor may be incorporated into the immersion plating bath. The metal plating is usually with silver or bismuth and the pads and/or through-holes comprise copper.

Solderability enhancement by silver immersion printed circuit board manufacture

In PCB manufacture, the pads and/or through-holes of a bare board are protected prior to mounting of other components by a silver plating process. The silver plate is applied from a plating composition by a replacement process in which silver ions oxidized copper and deposit a layer of silver at the surface. In the aqueous plating composition the silver ions are maintained in solution by the incorporation of a multidentate complexing agent. The compositions may contain a silver tarnish inhibitor and are free of reducing agent capable of reducing silver ions to silver metal, halide ions and substantially free of non-aqueous solvent. Surface mounted components can be soldered direct to the silver coated contact using any commercially available solder. Silver does not deposit onto solder mask, but only onto metal which is less electropositive than silver. REEXAMINATION RESULTS The questions raised in reexamination proceedings Nos. 90/012,336 and 90/009,934, filed Jun. 4, 2012 and Aug. 3, 2011 respectively, have been considered, and the results thereof are reflected in this reissue patent which constitutes the reexamination certificate required by 35 U.S.C. 307 as provided in 37 CFR 1.570(e) forreexaminations, and/or the reexamination certificate required by 35 U.S.C. 316 as provided in 37 CFR 1.997(e) forreexaminations.

Process for silver plating in printed circuit board manufacture

In PCB manufacture, the pads and/or through-holes of a bare board are protected prior to mounting of other components by a silver plating process. The silver plate is applied from a plating composition by a replacement process in which silver ions oxidized copper and deposit a layer of silver at the surface. In the aqueous plating composition the silver ions are maintained in solution by the incorporation of a multidentate complexing agent. The compositions may contain a silver tarnish inhibitor and are free of reducing agent capable of reducing silver ions to silver metal, halide ions and substantially free of non-aqueous solvent. Surface mounted components can be soldered direct to the silver coated contact using any commercially available solder. Silver does not deposit onto solder mask, but only onto metal which is less electropositive than silver.

Printed circuit board manufacture

Copper-containing surfaces, such as a copper surface for use in an electrical circuit, are protected by the provision of a bismuth metal coating immersion-plated from a moderately to strongly acidic plating bath. The plating bath preferably contains dissolved bismuth, halide, and a sulfur-containing ligand as a complexing agent that promotes adhesion of the bismuth coating. The bath may be formed from a concentrate system combined with water. The concentrate system may be a two-component system having an acidic first component containing the bismuth, halide, and sulfur-containing ligand, and an alkaline second component containing an additional complexing agent (e.g., EDTA salt). Tarnish resistance of the plated bismuth can be improved by the application of an alkaline composition to neutralize residual acid. Plating thickness can be enhanced by pre-cleaning the surface to be plated with a pre-cleaner containing nitric acid.

Bismuth coating protection for copper

A post-treatment method for copper on printed circuit boards is disclosed. The method comprises forming a cupric-based organometallic conversion coating on a copper surface of a printed circuit board, and then converting the cupric-based organometallic conversion coating to a cuprous-based organometallic conversion coating. The resulting cuprous-based organometallic conversion coating is desirable in that it improves copper to dielectric bond integrity.

Post-treatment for copper on printed circuit boards

A process for copper coating printed circuit boards is disclosed. The process includes a treating step in which a metal surface is contacted with an adhesion promotion composition material. The adhesion promotion material includes 0.1 to 20% by weight hydrogen peroxide, an inorganic acid, an organic corrosion inhibitor and a surfactant.

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Mission Viejo, CA, United States of America

Peter Thomas McGrath