Gold electroplating solution and method

Patent metadata

Field	Value
Publication number	US-2016208401-A1
Application number	US-201614996412-A
Country	US
Kind code	A1
Filing date	Jan 15, 2016
Priority date	Jan 16, 2015
Publication date	Jul 21, 2016
Grant date	—

Abstract

A gold electroplating solution includes a gold (III) cyanide compound, a chloride compound, and hydrochloric acid. The gold (III) cyanide compound is potassium gold (III) cyanide, ammonium gold (III) cyanide, or sodium gold (III) cyanide. The chloride compound is potassium chloride, ammonium chloride, or sodium chloride. Various structures may be made with the gold electroplating solution having a gold layer deposited directly on the stainless steel (SST) layer using a photolithography process. Such structures include a gold pattern having a discontinuous pattern, a bond pad region having one or more traces on the opposite side of the dielectric layer, a gimbal having gold bond pads, and a bonding joint having an electrical interface including a gold layer.

First claim

1 . A gold electroplating solution comprising:
a gold (III) cyanide compound, the gold (III) cyanide compound being at least one of potassium gold (III) cyanide, ammonium gold (III) cyanide, and sodium gold (III) cyanide; a chloride compound, the chloride compound being at least one of potassium chloride, ammonium chloride, and sodium chloride; and hydrochloric acid.

2 . The solution of claim 1 , wherein the gold (III) cyanide compound is one of potassium gold (III) cyanide, ammonium gold (III) cyanide, and sodium gold (III) cyanide; and the chloride compound is one of potassium chloride, ammonium chloride, and sodium chloride; wherein if the gold (III) cyanide compound is potassium gold (III) cyanide, then the chloride compound is potassium chloride; if the gold (III) cyanide compound is ammonium gold (III) cyanide, then the chloride compound is ammonium chloride; and if the gold (III) cyanide compound is sodium gold (III) cyanide, then the chloride compound is sodium chloride.

3 . The solution of claim 2 , wherein the gold (III) cyanide compound is potassium gold (III) cyanide and the chloride compound is potassium chloride.

4 . The solution of claim 1 , wherein the solution has a pH between about 0 and about 1.

5 . The solution of claim 4 , wherein the solution has a pH between about 0.7 and about 0.9.

6 . The solution of claim 1 , wherein a concentration of the gold (III) cyanide compound is between about 1.0 grams of gold per liter of solution and 3.0 grams of gold per liter of solution, and a concentration of chloride anions is between about 0.30 moles per liter of solution and 0.60 moles per liter of solution.

7 . The solution of claim 6 , wherein a concentration of the gold (III) cyanide is between about 1.8 grams of gold per liter of solution and 2.2 grams of gold per liter of solution, and a concentration of chloride anions is between about 0.45 moles per liter of solution and 0.55 moles per liter of solution.

8 . The solution of claim 1 , wherein the solution is free of ethylenediamine hydrochloride.

9 . The aqueous solution of claim 1 , wherein the solution is free of oxidizing acids.

10 . The aqueous solution of claim 9 , wherein the solution is free of nitric acid.

11 . A method of producing an electrodeposited gold pattern directly onto a stainless steel surface, the method comprising:
creating a photoresist pattern on the stainless steel surface; cleaning portions of the stainless steel surface not covered by the photoresist pattern; immersing the stainless steel surface in a gold electroplating solution, wherein the gold electroplating solution includes:
a gold (III) cyanide compound, the gold (III) cyanide compound being one of potassium gold (III) cyanide, ammonium gold (III) cyanide, and sodium gold (III) cyanide;
a chloride compound, the chloride compound being one of potassium chloride, ammonium chloride, and sodium chloride; and
hydrochloric acid,
wherein if the gold (III) cyanide compound is potassium gold (III) cyanide, then the chloride compound is potassium chloride; if the gold (III) cyanide compound is ammonium gold (III) cyanide, then the chloride compound is ammonium chloride, and if the gold (III) cyanide compound is sodium gold (III) cyanide, then the chloride compound is sodium chloride; and
applying a voltage between an anode within the gold electroplating solution and the stainless steel surface to generate a current from the anode to the stainless steel surface to electroplate gold from the gold electroplating solution onto the stainless steel surface.

12 . The method of claim 11 , wherein the gold (III) cyanide compound is potassium gold (III) cyanide and the chloride compound is potassium chloride.

13 . The method of claim 12 , further comprising adding sufficient hydrochloric acid to the gold electroplating solution such that the gold electroplating solution has a pH between about 0 and about 1.

14 . The method of claim 13 , further comprising adding sufficient hydrochloric acid to the gold electroplating solution such that the gold electroplating solution has a pH between about 0.7 and about 0.9.

15 . The method of claim 12 , further comprising maintaining a concentration of potassium gold (III) cyanide in the gold electroplating solution between about 1.0 grams of gold per liter of solution and 3.0 grams of gold per liter of solution, and maintaining a concentration of chloride anions in the gold electroplating solution between about 0.30 moles per liter of solution and 0.60 moles per liter of solution.

16 . The method of claim 15 , further comprising maintaining a concentration of potassium gold (III) cyanide in the gold electroplating solution between about 1.8 grams of gold per liter of solution and 2.2 grams of gold per liter of solution, and maintaining a concentration of chloride anions in the gold electroplating solution between about 0.45 moles per liter of solution and 0.55 moles per liter of solution.

17 . The method of claim 11 , wherein cleaning the stainless steel surface includes an oxygen plasma cleaning process.

18 . The method of claim 11 , wherein the voltage generates a continuous direct current, and wherein the continuous direct current produces a current density at the stainless steel surface of between 1 ampere per square decimeter and 40 amperes per square decimeter.

19 . The method of claim 11 , wherein the voltage generates a pulsed direct current.

20 . The method of claim 19 , where the pulsed direct current produces a time averaged current density at the stainless steel surface of between 1 ampere per square decimeter and 40 amperes per square decimeter.

21 . The method of claim 11 for depositing gold on a stainless steel surface of a disk drive head suspension, an optical image stabilization suspension, or a medical device.

Assignees

• Hutchinson Technology

Inventors

• Swanson Kurt C
• Riemer Douglas P
• Fank Steven A

Classifications

• C25D5/36

  of iron or steel · CPC title

• C25D5/02

  Electroplating of selected surface areas · CPC title

• C25D3/48 Primary

  of gold · CPC title

• C25D7/00

  Electroplating characterised by the article coated · CPC title

• C25D5/611

  Smooth layers · CPC title