# US 2021/0172082 A1 · Acidic aqueous binary silver-bismuth alloy electroplating compositions and methods

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- Number: US 2021/0172082 A1
- Document ID: US20210172082A1
- Status: Published application
- Kind: A1
- Application number: 16/708,783
- Filed: 2019-12-10
- Published: 2021-06-10
- Earliest claimed: 2019-12-10
- Applicants: Rohm and Haas Electronic Materials LLC
- Inventors: Miguel A. Rodriguez; Michael Lipschutz; Jamie Y.C. Chen; Youngmin Yoon
- Web page: https://patentgrep.com/patent/US20210172082A1

## CPC

- C25D 3/46: of silver
- C25D 3/64: containing more than 50% by weight of silver
- C22C 5/06: Alloys based on silver
- C25D 3/52: characterised by the organic bath constituents used
- C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

Aqueous acid binary silver-bismuth alloy electroplating compositions and methods enable electroplating silver rich binary silver-bismuth deposits. The aqueous acid binary silver-bismuth alloy electroplating compositions include 5-membered heterocyclic nitrogen compounds with a thiol functionality which enable deposition of the silver rich binary silver-bismuth alloys. The silver rich silver-bismuth deposits are matte to semi-bright, uniform and have a low coefficient of friction.

## Claims

### Claim 1

A binary silver-bismuth alloy electroplating composition comprising a source of silver ions, a source of bismuth ions, and a 5-membered aromatic heterocyclic nitrogen compound having a general formula:
wherein Q1-Q4 can be a substituted or unsubstituted nitrogen or a substituted or unsubstituted carbon with the proviso that at least two of Q1-Q4 are nitrogen, wherein substituent groups include, but are not limited to, (C1-C4)alkyl, amino group, aminoalkyl group, carboxyl, carboxy(C1-C4)alkyl or alkylsulfonate, and a pH of less than 7.

### Claim 2 (depends on 1)

The binary silver-bismuth alloy electroplating composition of claim 1, wherein the 5-membered aromatic heterocyclic nitrogen compound is selected from the group consisting of 3-mercapto-1,2,4-triazole, 3-amino-1,2,4-triazole-5-thiol, 3-amino-5-mercapto-1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2,4-triazole, 1H-imidazole-2-thiol, salts of the 5-membered aromatic heterocyclic nitrogen compounds, and mixtures thereof.

### Claim 3 (depends on 1)

The binary silver-bismuth alloy electroplating composition of claim 1, further, comprising a thioether or mixtures thereof.

### Claim 4 (depends on 3)

The binary silver-bismuth alloy electroplating composition of claim 3, wherein the thioether is a hydroxy bis-sulfide compound.

### Claim 5 (depends on 1)

The binary silver-bismuth alloy electroplating composition of claim 1, further comprising an aliphatic thiol terminal compound or mixtures thereof.

### Claim 6 (depends on 5)

The binary silver-bismuth alloy electroplating composition of claim 5, wherein the aliphatic thiol terminal compound is selected from the group consisting of thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, cysteine, mercaptosuccinic acid, 3-mercapto-1-propanesulfonic acid, 2-mercaptoethanesulfonic acid, salts of the thiol terminal compounds, and mixtures thereof.

### Claim 7

A method of electroplating a binary silver-bismuth alloy on a substrate comprising:
a) providing the substrate;
b) contacting the substrate with a binary silver-bismuth alloy electroplating composition comprising a source of silver ions, a source of bismuth ions, and a 5-membered aromatic heterocyclic nitrogen compounds having general formula:
wherein Q1-Q4 can be a substituted or unsubstituted nitrogen or a substituted or unsubstituted carbon with the proviso that at least two of Q1-Q4 are nitrogen, wherein substituent groups include, but are not limited to, (C1-C4)alkyl, amino group, aminoalkyl group, carboxyl, carboxy(C1-C4)alkyl or alkysulfonate, and a pH of less than 7; and
c) applying an electric current to the binary silver-bismuth alloy electroplating composition and substrate to electroplate a binary silver-bismuth deposit on the substrate.

### Claim 8 (depends on 7)

The method of claim 7, wherein the 5-membered aromatic heterocyclic nitrogen compound is selected from the group consisting of 3-mercapto-1,2,4-triazole, 3-amino-1,2,4-triazole-5-thiol, 3-amino-5-mercapto-1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2,4-triazole, 1H-imidazole-2-thiol, salts of the 5-membered aromatic heterocyclic nitrogen compounds, and mixtures thereof.

### Claim 9 (depends on 7)

The method of claim 7, wherein the binary silver-bismuth alloy electroplating composition further comprises a thioether or mixtures thereof.

### Claim 10 (depends on 7)

The method of claim 7, wherein the binary silver-bismuth electroplating composition further comprises an aliphatic thiol terminal compound or mixtures thereof.

### Claim 11

An article comprising a binary silver-bismuth alloy layer adjacent a surface of a substrate, wherein the binary silver-bismuth alloy layer comprises 90% to 99.8% silver and 0.2% to 10% bismuth, and has a coefficient of friction of 1 or less.