IP Library › Granted Patent US 7,591,956
Granted Patent B2
US 7,591,956 · App. 11/416,729 · Granted Sep 22, 2009

Method and composition for selectively stripping nickel from a substrate

View Patent ↗
Loading inventors, assignments & file history…
Monitor This Case
Get email alerts when status or documents change.
Order Certified Copies
Most orders are placed with the USPTO same day — all within 24 business hours.
Order via The Patent Place →
Pre-filled with this patent's details
Quick Facts
Patent No.
US 7,591,956
App. No.
11/416,729
Granted
Sep 22, 2009
Kind
B2
Abstract

A method of stripping nickel from a printed wiring board comprises providing a printed wiring board with a nickel deposit on a surface and contacting the nickel deposit with phosphate ions and an oxidizer. An aqueous solution comprises ammonium ions, phosphate ions and an oxidizing agent present in amounts effective to strip nickel. An aqueous solution comprises about 1% to about 10% by weight hydrogen peroxide and about 5% to about 30% by weight of an ammonium phosphate. A method of pre-treating a copper substrate comprises providing a printed wiring board having a copper substrate and contacting the copper substrate with phosphate ions, and an oxidizer. A method of neutralizing permanganate on a printed wiring board comprises providing a printed wiring board with a permanganate residue on the printed wiring board and contacting the permanganate residue with phosphate ions, and an oxidizer.

Claims (36)

1. A method of stripping nickel from a printed wiring board, comprising:

providing a printed wiring board comprising a nickel deposit on a copper surface; and

contacting the nickel deposit with

phosphate ions, and

an oxidizer;

wherein said contacting step occurs at a pH between about 2.3 and about 5.0 and under conditions effective to remove at least a portion of the nickel deposit from the copper surface without damaging a soldermask on the printed wiring board.

2. The method of claim 1 wherein said copper surface is bright after said contacting step.

3. The method of claim 1 wherein said copper surface is uniform after said contacting step.

4. The method of claim 1 wherein said copper surface is ready for re-working after said contacting step.

5. The method of claim 1 wherein said nickel deposit comprises electroless nickel.

6. The method of claim 1 further comprising subsequently depositing nickel on said copper surface.

7. The method of claim 1 wherein said copper surface is not significantly etched after said contacting step.

8. The method of claim 1 further comprising contacting said nickel deposit with ammonium ions.

9. The method of claim 1 wherein said phosphate ions are provided in an aqueous solution at a concentration of at least about 10 g/L.

10. The method of claim 1 wherein said oxidizer is provided in an aqueous solution at a concentration of about 15 to about 100 g/L.

11. The method of claim 1 wherein said contacting step occurs at a temperature between about 0 and about 100° C.

12. The method of claim 1 wherein the duration of said contacting step is from about 5 to about 600 minutes.

13. The method of claim 1 wherein said phosphate ions, and oxidizer are provided in the form of a single solution.

14. The method of claim 1 wherein said contacting step is carried out by forming a bath of phosphate ions and peroxide in aqueous solution and immersing said nickel deposit in said bath.

15. The method of claim 1 wherein said conditions are effective to remove substantially all of said nickel deposit from at least a portion of said copper surface.

16. The method claim of 15 further comprising contacting said copper surface with an etching solution.

17. The method of claim 1 wherein said oxidizer is selected from the group consisting of peroxides, persulfates and nitric acid.

18. A method of pre-treating a copper substrate comprising:

providing a printed wiring board comprising a copper substrate; and

contacting the copper substrate with

phosphate ions, and

an oxidizer;

wherein said contacting step occurs at a pH between about 2.3 and about 5.0 and under conditions effective to brighten the copper substrate without damaging a soldermask on the printed wiring board.

19. The method of claim 18 further comprising contacting said copper substrate with ammonium ions.

20. A method of neutralizing permanganate on a printed wiring board comprising:

providing a printed wiring board with a permanganate residue on the printed wiring board; and

contacting the permanganate residue with

phosphate ions, and

an oxidizer;

wherein said contacting step occurs at a pH between about 2.3 and about 5.0 and under conditions effective to neutralize the permanganate without damaging a soldermask on the printed wiring board.

21. The method of claim 20 further comprising contacting said permanganate residue with ammonium ions.

Assignments (11)
CHANGE OF NAME Recorded Feb 15, 2019
From: OMG ELECTRONIC CHEMICALS, LLC
To: MACDERMID ENTHONE AMERICA LLC
Reel/Frame 048356/0593 →
PATENT SECURITY AGREEMENT Recorded Feb 1, 2016
From: OMG ELECTRONIC CHEMICALS, LLC
To: BARCLAYS BANK PLC, AS COLLATERAL AGENT
Reel/Frame 037662/0086 →
TERMINATION AND RELEASE OF SECURITY INTEREST IN PATENTS Recorded Oct 28, 2015
From: PNC BANK
To: OMG ELECTRONIC CHEMICALS, LLC
Reel/Frame 036985/0566 →
SECURITY AGREEMENT Recorded Sep 12, 2013
From: OM GROUP, INC.; OMG ELECTRONIC CHEMICALS, LLC; OMG AMERICAS, INC.; EAGLEPICHER TECHNOLOGIES, LLC; EAGLEPICHER MEDICAL POWER, LLC
To: PNC BANK
Reel/Frame 031208/0876 →
RELEASE OF SECURITY INTEREST Recorded Sep 5, 2013
From: BANK OF AMERICA, N.A.
To: OM GROUP, INC.; EAGLEPICHER TECHNOLOGIES, LLC; EAGLEPICHER MEDICAL POWER, LLC; OMG AMERICAS, INC.; OMG ELECTRONIC CHEMICALS, LLC
Reel/Frame 031169/0976 →
SECURITY AGREEMENT Recorded Aug 12, 2011
From: OM GROUP, INC., A DELAWARE CORPORATION; COMPUGRAPHICS U.S.A. INC., A DELAWARE CORPORATION; CYANTEK CORPORATION, A DELAWARE CORPORATION; OMG AMERICAS, INC., A OHIO CORPORATION; OMG ELECTRONIC CHEMICALS, LLC, A DELAWARE LIMITED LIABILITY COMPANY; OMG ENERGY HOLDINGS, INC., A DELAWARE CORPORATION; OMG HARKO HOLDINGS, LLC, A DELAWARE LIMITED LIABILITY COMPANY; EAGLEPICHER MEDICAL POWER, LLC, A DELAWARE LIMITED LIABILITY COMPANY; EAGLEPICHER TECHNOLOGIES, LLC, A DELAWARE LIMITED LIABILITY COMPANY; EPEP HOLDING COMPANY, LLC, A DELAWARE LIMITED LIABILITY COMPANY
To: BANK OF AMERICA, N.A., AS COLLATERAL AGENT
Reel/Frame 026740/0353 →
PATENT RELEASE AGREEMENT Recorded Aug 10, 2011
From: PNC BANK, NATIONAL ASSOCIATION, AS ADMINISTRATIVE AGENT
To: OM GROUP, INC., A DELAWARE CORPORATION; OMG AMERICAS, INC., A OHIO CORPORATION; OMG ELECTRONIC CHEMICALS, INC., A DELAWARE LIMITED LIABILITY COMPANY; COMPUGRAPHICS U.S.A. INC., A DELAWARE CORPORATION; OMG ENERGY HOLDINGS, INC., A DELAWARE CORPORATION; EAGLEPICHER TECHNOLOGIES, LLC, A DELAWARE LIMITED LIABILITY COMPANY; EPEP HOLDING COMPANY, LLC, A DELAWARE LIMITED LIABILITY COMPANY; EAGLEPICHER MEDICAL POWER, LLC, A DELAWARE LIMITED LIABILITY COMPANY
Reel/Frame 026727/0485 →
CHANGE OF NAME Recorded Aug 11, 2010
From: OMG ELECTRONIC CHEMICALS, INC.
To: OMG ELECTRONIC CHEMICALS, LLC
Reel/Frame 024812/0920 →
SECURITY AGREEMENT Recorded Mar 11, 2010
From: OM GROUP, INC.; OMG AMERICAS, INC.; OMG ELECTRONIC CHEMICALS, INC.; COMPUGRAPHICS U.S.A. INC.; OM HOLDINGS, INC.; OMG ENERGY HOLDINGS, INC.; EAGLEPICHER TECHNOLOGIES, LLC; EPEP HOLDING COMPANY, LLC; EAGLEPICHER MEDICAL POWER, LLC
To: PNC BANK, NATIONAL ASSOCIATION
Reel/Frame 024066/0130 →
MERGER Recorded Jan 14, 2009
From: ELECTROCHEMICALS INC.; OMG FIDELITY, INC.
To: OMG ELECTRONIC CHEMICALS, INC.
Reel/Frame 022105/0163 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Jul 31, 2006
From: BERNARDS, ROGER F.; BOWERS, JOSEPH S.
To: ELECTROCHEMICALS, INC.
Reel/Frame 018105/0479 →