Acidic aqueous binary silver-bismuth alloy electroplating compositions and methods

Patent metadata

Field	Value
Publication number	US-2021172082-A1
Application number	US-201916708783-A
Country	US
Kind code	A1
Filing date	Dec 10, 2019
Priority date	Dec 10, 2019
Publication date	Jun 10, 2021
Grant date	—

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.

First claim

What is claimed is:

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 Q 1 -Q 4 can be a substituted or unsubstituted nitrogen or a substituted or unsubstituted carbon with the proviso that at least two of Q 1 -Q 4 are nitrogen, wherein substituent groups include, but are not limited to, (C 1 -C 4 )alkyl, amino group, aminoalkyl group, carboxyl, carboxy(C 1 -C 4 )alkyl or alkylsulfonate, and a pH of less than 7.

2 . 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.

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

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

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

6 . 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.

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 Q 1 -Q 4 can be a substituted or unsubstituted nitrogen or a substituted or unsubstituted carbon with the proviso that at least two of Q 1 -Q 4 are nitrogen, wherein substituent groups include, but are not limited to, (C 1 -C 4 )alkyl, amino group, aminoalkyl group, carboxyl, carboxy(C 1 -C 4 )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.

8 . 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.

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

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

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.

Assignees

• Rohm & Haas Elect Mat

Inventors

• Rodriguez Miguel A
• Lipschutz Michael
• Chen Jamie Y C
• Yoon Youngmin

Classifications

• C25D3/64 Primary

  containing more than 50% by weight of silver · CPC title

• C22C5/06

  Alloys based on silver · CPC title

• C25D3/46 Primary

  of silver · CPC title

• C25D3/52

  characterised by the organic bath constituents used · CPC title