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US 4,121,982 AGranted
Gold alloy plating bath and method
AssigneeAmerican Chemical & Refining Company Incorporated
InventorsWilliam L. Moriarty, Augustus Fletcher
Life of this patent
Estimating the term…
Abstract
An aqueous bath for electroplating a gold/silver alloy includes a water soluble electrolyte such as potassium pyrophosphate, gold and silver present as their respective alkali metal cyanides, and a water soluble brightener system. The water soluble brightener system comprises a selenium compound containing selenium in the -2 valance state and a polyethyleneimine compound. The bath has a pH of about 8 to 10 and may include tetraethanolamine borate ester to decrease the tensile stress of the electrodeposit.
Claims19
In a bath for electroplating a gold/silver alloy, the combination comprising an aqueous solution of:
- (a) at least one water soluble electrolyte selected from the class consisting of alkali metal salts of boric acid, citric acid, phosphoric acid, pyrophosphoric acid and tartaric acid present in a quantity at least sufficient to render the bath electrically conductive for electroplating gold and silver therefrom;
- (b) gold ion provided by an alkali metal gold cyanide, said gold being present in an amount from 1 gram per liter up to that provided by saturation of said bath with said alkali metal gold cyanide;
- and
- (c) silver ion provided by an alkali metal silver cyanide, said silver being present in an amount from 1/2 gram per liter up to that provided by saturation of said bath with said alkali metal silver cyanide;
- and
- (d) a water soluble brightener system comprising selenium ion provided by a water soluble selenium compound containing selenium in the -2 oxidation state and a water soluble ethyleneimine compound, said selenium ion being present in the amount of about 0.1 to 0.5 ppm selenium for each gram per liter of silver ion, and said ethyleneimine compound being present in the amount of about 4 to 75 ppm ethyleneimine compound for each gram per liter of gold ion;
- said bath having a pH of about 8 to 10.
4 more elements
In a bath for electroplating a gold/silver alloy, the combination comprising an aqueous solution of:
- (a) about 10 to 600 grams per liter of at least one of a water soluble electrolyte selected from the class consisting of alkali metal salts of:
- boric acid, citric acid, phosphoric acid, pyrophosphoric acid and tartaric acid;
- (b) 0 to about 140 grams per liter of tetraethanolamineborate ester;
- (c) about 1.5 to 50 grams per liter of gold ion provided by an alkali metal gold cyanide;
- (d) about 1 to 26 grams per liter of silver ion provided by an alkali metal silver cyanide;
- and
- (e) a water soluble brightener system comprising about 0.125 to 8 ppm of selenium provided by a water soluble compound containing selenium in the -2 oxidation state, and about 12 to 1800 ppm of polyethyleneimine, said polyethyleneimine being present in the amount of about 8 to 36 ppm for each gram of gold ion;
- said bath having a pH of about 8 to 10.
5 more elements
In a bath for electroplating a gold/silver alloy, the combination comprising an aqueous solution of:
- (a) about 37.5 to 150 grams per liter of at least one of a water soluble electrolyte selected from the class consisting of alkali metal salts of:
- boric acid, citric acid, phosphoric acid, pyrophosphoric acid and tartaric acid;
- (b) up to about 37.5 grams per liter of tetraethanolamineborate ester;
- (c) about 6 to 12.5 grams per liter of gold ion provided by an alkali metal gold cyanide;
- (d) about 4 to 6.5 grams per liter of silver ion provided by an alkali metal silver cyanide;
- and
- (e) a water soluble brightener system comprising about 0.5 to 2 ppm of selenium provided by a water soluble compound containing selenium in the -2 oxidation state, and about 50 to 450 ppm of polyethyleneimine, said bath having a pH of about 8 to 10.
4 more elements
In the method of electroplating gold/silver deposits upon a workpiece, the steps comprising:
- A. immersing a workpiece having an electrically conductive surface into an aqueous bath having a pH of about 8 to 10 and comprising:
- (1) at least one water soluble electrolyte selected from the class consisting of alkali metal salts of boric acid, citric acid, phosphoric acid, pyrophosphoric acid and tartaric acid present in a quantity at least sufficient to render the bath electrically conductive for electroplating gold and silver therefrom;
- (2) gold ion provided by an alkali metal gold cyanide, said gold being present in an amount from 1 gram per liter up to that provided by saturation of said bath with said alkali metal gold cyanide;
- (3) silver ion provided by an alkali metal silver cyanide, said silver being present in an amount from 1/2 gram per liter up to that provided by saturation of said bath with said alkali metal silver cyanide;
- and
- (4) a water soluble brightener system comprising selenium ion provided by a water soluble selenium compound containing selenium in the -2 oxidation state and a water soluble ethyleneimine compound, said selenium ion being present in the amount of about 0.1 to 0.5 ppm selenium for each gram per liter of silver ion, and said ethyleneimine compound being present in the amount of about 4 to 75 ppm ethyleneimine compound for each gram per liter of gold ion;
- B. maintaining the temperature of said bath at 26.degree.-44.degree. C.;
- C. applying an electrical potential across said workpiece and an anode inert to said bath, said potential providing a current density of about 6-18 amperes per square foot;
- and
- D. removing the electroplated workpiece from said bath.
7 more elements
In the method of electroplating gold/silver deposits upon a workpiece, the steps comprising:
- A. immersing a workpiece having an electrically conductive surface into an aqueous bath having a pH of about 8 to 10 and comprising:
- (1) about 37.5 to 150 grams per liter of at least one of a water soluble electrolyte selected from the class consisting of alkali metal salts of:
- boric acid, citric acid, phosphoric acid, pryophosphoric acid and tartaric acid;
- (2) up to about 37.5 grams per liter of tetraethanolamineborate ester;
- (3) about 6 to 12.5 grams per liter of gold ion provided by an alkali metal gold cyanide;
- (4) about 4 to 6.5 grams per liter of silver ion provided by an alkali metal silver cyanide;
- and
- (5) a water soluble brightener system comprising about 0.5 to 2 ppm of selenium provided by a water soluble compound containing selenium in the -2 oxidation state, and about 50 to 450 ppm of polyethyleneimine;
- B. maintaining the temperature of said bath at 26.degree.-44.degree. C.;
- C. applying an electrical potential across said workpiece and an anode inert to said bath, said potential providing a current density of about 6-18 amperes per square foot;
- and
- D. removing the electroplated workpiece from said bath.
9 more elements
Dependencies are inferred from the claim text.