Acid aqueous binary silver-bismuth alloy electroplating compositions and methods

Patent metadata

Field	Value
Publication number	US-11434577-B2
Application number	US-202017008691-A
Country	US
Kind code	B2
Filing date	Sep 1, 2020
Priority date	Oct 17, 2019
Publication date	Sep 6, 2022
Grant date	Sep 6, 2022

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 thiol terminal aliphatic compounds having carboxyl or sulfonic groups which enable deposition of silver rich binary silver-bismuth alloys having deposits which 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 thiol terminal aliphatic compound chosen from one or more of 2-mercaptopropionic acid, 3-mercaptopropionic acid, cysteine, mercaptosuccinic acid, 3-mercapto-1-propanesulfonic acid, 2-mercaptoethanesulfonic acid and salts of the thiol terminal compounds, and a pH of less than 7.

2. The binary silver-bismuth alloy electroplating composition of claim 1 , further comprising one or more hydroxy bis-sulfide compounds.

3. The binary silver-bismuth alloy electroplating composition of claim 1 , further comprising one or more acids or salts thereof.

4. The binary silver-bismuth alloy electroplating composition of claim 1 , further comprising one or more pH adjusting agents.

5. The binary silver-bismuth alloy electroplating composition of claim 1 , wherein the pH is from 0 to 6.

6. 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 thiol terminal aliphatic compound 2-mercaptopropionic acid, 3-mercaptopropionic acid, cysteine, mercaptosuccinic acid, 3-mercapto-1-propanesulfonic acid, 2-mercaptoethanesulfonic acid and salts of the thiol terminal compounds, 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.

7. The method of claim 6 , wherein the binary silver-bismuth alloy electroplating composition further comprises one or more dihydroxy bis-sulfide compounds.

8. The method of claim 6 , wherein the binary silver-bismuth electroplating composition further comprises one or more acids and salts thereof.

9. The method of claim 6 , wherein the binary silver-bismuth alloy electroplating composition further comprises one or more pH adjusting agents.

10. The method of claim 6 , wherein the binary silver-bismuth alloy electroplating composition has a pH of 0 to 6.

Assignees

• Rohm & Haas Elect Mat

Inventors

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

Classifications

• C25D7/00

  Electroplating characterised by the article coated · CPC title

• C25D3/64 Primary

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

• C25D21/12

  Process control or regulation (controlling or regulating in general G05) · CPC title