Environmentally friendly gold electroplating compositions and methods

Patent metadata

Field	Value
Publication number	US-2016145756-A1
Application number	US-201414549571-A
Country	US
Kind code	A1
Filing date	Nov 21, 2014
Priority date	Nov 21, 2014
Publication date	May 26, 2016
Grant date	—

Abstract

Gold electroplating compositions are substantially free of many environmental toxins to provide an environmentally friendly pure gold electroplating composition. The substantially pure gold electroplating compositions may electroplate gold over a broad current density range to deposit bright to matte gold layers on various types of electronic components and decorative articles.

First claim

What is claimed is:

1 . A gold electroplating composition comprising one or more sources of gold ions from gold-cyanide salts, one or more sources of phosphate ions, one or more sources of phosphonic acids or salts thereof, sodium potassium tartrate and one or more sources of antimony (III) ions, the gold electroplating composition is free of free-cyanide.

2 . The gold electroplating composition of claim 1 , wherein the gold-cyanide salts are chosen from potassium gold cyanide, sodium gold cyanide, and ammonium gold cyanide.

3 . The gold electroplating composition of claim 1 , wherein the one or more sources of phosphate ions are chosen from phosphoric acid, sodium dihydrogenate phosphate and potassium dihydrogenate phosphate.

4 . The gold electroplating composition of claim 1 , wherein the one or more phosphonic acids have a formula:

wherein n is an integer from 2 to 3, M 1 and M 2 may be the same or different and are chosen from hydrogen, ammonium, lower alkyl amine or an alkali metal cation and Z is a radical equal in valence to n and is a linear or branched, substituted or unsubstituted (C 1 -C 12 )alkyl or an N-substituted (C 2 -C 3 )alkyl wherein the Z radical has a carbon atom linked to a phosphorus atom of formula (I).

5 . The gold electroplating composition of claim 1 , wherein the one or more sources of antimony (III) ions are chosen from potassium antimony tartrate, sodium antimony tartrate, antimony sulfate and antimony chloride.

6 . The gold electroplating composition of claim 1 , wherein the gold electroplating composition is substantially free lead, arsenic, thallium, hydrazine and sulfites.

7 . A method of electroplating gold comprising:
a. providing a gold electroplating composition comprising one or more sources of gold ions from gold-cyanide salts, one or more sources of phosphate ions, one or more sources of phosphonic acids or salts thereof, sodium potassium tartrate and one or more sources of antimony (III) ions, the gold electroplating composition is substantially free of free-cyanide; b. contacting a substrate with the gold electroplating composition; and c. electroplating gold on the substrate using direct current or pulse current at a current density of 0.03 ASD or greater.

8 . The method of electroplating gold of claim 7 , wherein the current density is from 1 ASD to 50 ASD.

9 . The method of electroplating gold of claim 7 , wherein the gold-cyanide salts are chosen from potassium gold cyanide, sodium gold cyanide, and ammonium gold cyanide.

10 . The method of electroplating gold of claim 7 , wherein the one or more sources of phosphate ions are chosen from phosphoric acid, sodium dehydrogenate phosphate and potassium dehydrogenate phosphate.

11 . The method of electroplating gold of claim 7 , wherein the one or more phosphonic acids have a formula:

wherein n is an integer from 2 to 3, M 1 and M 2 may be the same or different and are chosen from hydrogen, ammonium, lower alkyl amine or an alkali metal cation and Z is a radical equal in valence to n and is a linear or branched, substituted or unsubstituted (C 1 -C 12 )alkyl or an N-substituted (C 2 -C 3 )alkyl wherein the Z radical has a carbon atom linked to a phosphorus atom of formula (I).

12 . The method of electroplating gold of claim 7 , wherein the one or more sources of antimony (III) ions are chosen from potassium antimony tartrate, sodium antimony tartrate, antimony sulfate and antimony chloride.

13 . The method of electroplating gold of claim 7 , wherein the gold electroplating composition is substantially free of free-cyanide, lead, arsenic, thallium, hydrazine and sulfites.

14 . The method of electroplating gold of claim 7 , wherein the substrate is a printed circuit board, a contact for a connector, switch or decorative article.

Assignees

• Rohm & Haas Elect Mat

Inventors

• Foyet Adolphe
• Clauss Margit
• Buchs Reto

Classifications

• C25D3/62

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

• C25D3/48 Primary

  of gold · CPC title

• C25D5/18

  Electroplating using modulated, pulsed or reversing current · CPC title

• C25D7/00

  Electroplating characterised by the article coated · CPC title

• C25D7/005

  Jewels; Clockworks; Coins · CPC title