Akaline cyanide-free Cu-Zu strike baths and electrodepositing processes for the use thereof
AssigneeLeaRonal, Inc.
InventorsRobert Stavitsky, Basil D. Lovelock
Life of this patent
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Abstract
Alkaline cyanide-free copper strike baths are provided for the purposes of electrodepositing a copper-zinc alloy strike coating unto a metal based substrate so as to prevent immersion coating by the copper on the metal substrate and thereby provide a basis for the subsequent addition to the substrate of composite electrodeposits which are blister free and highly adherent. Electrochemical coating processes for employing such strike baths and the resulting products are disclosed.
Claims33
An alkaline cyanide-free strike bath capable of electrodepositing a copper-zinc alloy onto a substrate comprising zinc and consisting essentially of, dissolved in chelated form therein, copper, zinc, and chelating agent for said copper and zinc,
- said bath having a pH of about 7.5 to 12.0,
- each of said copper and zinc being present in amounts of about 1 to 15 grams/liter, and
- said chelating agent being capable of chelating divalent metal ions and being selected from the group consisting of organic phosphonic acids, organic phosphonates, pyrophosphates, polyphosphates, aminocarboxylic acids, 1,3-diketones, amino alcohols, aromatic heterocyclic bases, phenols, oximes, Schiff bases, tetrapyrroles, sulfur compounds, polyethylenimine, polymethacryloylacetone, and poly(p-vinylbenzyliminodiacetic acid) and derivatives and mixtures thereof, and being present in excess of the amount thereof required to completely complex the amount of copper and zinc present therein.
An alkaline cyanide-free strike bath capable of electroplating a copper-zinc alloy onto a substrate comprising zinc and without forming immersion coating comprising, dissolved in chelated form therein, copper, zinc and chelating agent for said copper and zinc,
- each of said copper and zinc being present in an amount of about 1 to 15 grams/liter, and
- said chelating agent being capable of chelating divalent metal ions and being only selected from the group consisting of pyrophosphates, organic phosphonic acids, organic phosphonates, polyphosphates, aminocarboxylic acids, 1,3-diketones, amino alcohols, aromatic hetrocyclic bases, phenols, oximes, Schiff bases, tetrapyrroles, sulfur compounds, polyethylenimine, polymethacryloylacetone, and poly(p-vinylbenzyliminodiacetic acid) and derivatives and mixtures thereof, and being present in excess of the amount thereof required to completely complex the copper and zinc values present therein, and
- said strike bath having a pH of about 7.5 to 12.0.
In a multistep electroplating process for electroplating a metal substrate comprising zinc with a copper coating without forming an immersion coating which process includes the step of electrodepositing an initial copper containing strike coating onto said substrate from an alkaline strike bath having a pH of about 7.5 to 12.0 and which is free of cyanide and glucoheptonic acid and salts thereof, the improvement which comprises adding zinc to said strike bath to prevent or retard the plating of copper on said substrate by immersion.
An alkaline cyanide-free strike bath having a pH of about 7.5 to 11 and capable of electrodepositing a copper-zinc alloy onto a substrate comprising zinc without forming an immersion coating and consisting essentially of, dissolved in chelated form therein, copper, zinc and chelating agent for said copper and zinc,
- each of said copper and zinc being present in an amount of about 1 to 15 grams/liters and said coper and zinc being present in a weight ratio to each other, in elemental form, of about 2 to 1 of copper to 0.5 to 1 of zinc, and
- said chelating agent being capable of chelating divalent metal ions and being a phosphorous containing compound selected from the group consisting of pyrophosphates, polyphosphates, organic phosphonates, and organic phosphonic acids.
Dependencies are inferred from the claim text.