Electroplating solutions

Patent metadata

Field	Value
Publication number	US-12442099-B2
Application number	US-202118250487-A
Country	US
Kind code	B2
Filing date	Dec 16, 2021
Priority date	Dec 18, 2020
Publication date	Oct 14, 2025
Grant date	Oct 14, 2025

Abstract

The invention relates to an aqueous electroplating solution for alkaline electroplating, comprising: [M(NH3)4]2+ ions, wherein M is selected from the group consisting of Pd or Pt; and organic anions selected from the group consisting of bicarbonate, carbonate, or a mixture thereof; wherein the following species, if present, are present in the following amounts: alkali metals in an amount of less than 5 g/L; compounds comprising phosphorus in an amount of less than 5 g/L; compounds comprising boron in an amount of less than 5 g/L. The invention also relates to an electroplating bath comprising the electroplating solution, and a method of forming a metal layer on a substrate by electroplating using the electroplating solution.

First claim

The invention claimed is:

1. An electroplating bath comprising a cathode and an anode which are both at least partially submerged in an electrolyte, wherein the electrolyte is an aqueous electroplating solution comprising
[Pt(NH 3 ) 4 ] 2+ ions; and organic anions selected from the group consisting of bicarbonate, carbonate, or a mixture thereof;
wherein the molar ratio of Pt: (bicarbonate+carbonate) is approximately 1:2; and
wherein the following species, if present, are present in the following amounts:
alkali metals in an amount of less than 5 g/L;
compounds comprising phosphorus in an amount of less than 5 g/L;

compounds comprising boron in an amount of less than 5 g/L.

2. The electroplating bath as claimed in claim 1 , wherein the concentration of Pt in the solution is 1 to 30 g/litre, on a metal basis.

3. The electroplating bath as claimed in claim 1 , wherein the pH of the solution is 8 to 14.

4. The electroplating bath as claimed in claim 1 , wherein the solution comprises a pH adjusting agent selected from the group consisting of ammonia, urea, an alkylammonium hydroxide, ammonium hydroxide, ammonium bicarbonate and ammonium carbonate.

5. The electroplating bath as claimed in claim 1 , wherein the content of alkali metals in the solution is less than 0.1 g/L.

6. A method of forming a metal layer on a substrate by electroplating, wherein electroplating is carried out using a bath comprising a cathode and an anode which are both at least partially submerged in an electrolyte, wherein the electrolyte is an aqueous electroplating solution comprising
[Pt(NH 3 ) 4 ] 2+ ions; and organic anions selected from the group consisting of bicarbonate, carbonate, or a mixture thereof;
wherein the molar ratio of Pt: (bicarbonate+carbonate) is approximately 1:2; and
wherein the following species, if present, are present in the following amounts:
alkali metals in an amount of less than 5 g/L;
compounds comprising phosphorus in an amount of less than 5 g/L;

compounds comprising boron in an amount of less than 5 g/L.

7. The method as claimed in claim 6 , wherein electroplating is carried out at a temperature of 80° C. or more.

8. The method as claimed in claim 6 , wherein electroplating is carried out at a temperature of 60 to 100° C. or more and a pH of 8 to 14.

9. The method as claimed in claim 6 , wherein the bath is replenished with fresh electroplating solution as required.

10. The method as claimed in claim 6 , wherein a pH adjusting agent is added to the bath as required.

11. The method as claimed in claim 6 , wherein the cathode provides the substrate to be coated.

12. The method as claimed in claim 6 , comprising a step of pausing electroplating and increasing the temperature of the electrolyte in order to purge the bath of residual organic anion.

13. The method as claimed in claim 6 , wherein the cathode acts as the substrate and is selected from jewellery, a medical component or an aviation component.

14. The method as claimed in claim 6 , wherein the concentration of Pt in the solution is 1 to 30 g/litre, on a metal basis.

15. The method as claimed in claim 6 , wherein the pH of the solution is 8 to 14.

16. The method as claimed in claim 6 , wherein the solution comprises a pH adjusting agent selected from the group consisting of ammonia, urea, an alkylammonium hydroxide, ammonium hydroxide, ammonium bicarbonate and ammonium carbonate.

17. The method as claimed in claim 6 , wherein the content of alkali metals in the solution is less than 0.1 g/L.

Assignees

• Johnson Matthey Plc

Inventors

• Boardman Alan

Classifications

• C25D3/50 Primary

  of platinum group metals · CPC title

• C25D7/005

  Jewels; Clockworks; Coins · CPC title

• C25D3/52 Primary

  characterised by the organic bath constituents used · CPC title