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US4448648A
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Trivalent chromium electroplating baths
Assignee: International Business Machines Corp
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Filing: 1982-11-01
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Granted: 1984-05-15
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Expires: 2002-11-01
Abstract
Abstract A trivalent chromium electroplating solution containing trivalent chromium ions, a complexant, a buffer and a sulphur species having S--O or S--S bonds. The complexant is selected to give the chromium complex a stability constant, K 1 , in the range 10 6 <K 1 <10 12 M -1 .
Inventors
- 👤 Donald J. Barclay
- 👤 William M. Morgan
- 👤 James M. Vigar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 08:45
CPC Classifications
C; C25; C25D; C25D3/00; C25D3/02; C25D3/56; C25D3/04; C25D3/06
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
71 words
A chromium electroplating electrolyte containing a source of trivalent chromium ions, a complexant, a buffer and a sulphur species selected from the group consisting of thiosulphates, thionates, polythionates and sulfoxylates for promoting chromium deposition, the complexant being selected so that the stability constant K 1 of the reaction between the chromium ions and the complexant is in the range 10 6 <K 1 <10 12 M -1 at about 25° C.
Claim 2
Dependent Claim
71 words
A chromium electroplating electrolyte containing a source of trivalent chromium ions, a complexant, a buffer and a sulphur species selected from the group consisting of thiosulphates, thionates, polythionates and sulfoxylates for promoting chromium deposition, the complexant being selected so that the stability constant K 1 of the reaction between the chromium ions and the complexant is in the range 10 6 <K 1 <10 12 M -1 at about 25° C.
Claim 3
Dependent Claim
25 words
An electrolyte as claimed in claim 1 in which the complexant is selected from aspartic acid, iminodiacetic acid, nitrilotriacetic acid, 5-sulphosalicylic acid or critic acid.
Claim 4
Dependent Claim
24 words
An electrolyte as claimed in claim 2 in which the source of chromium is chromium sulphate, and including conductivity ions selected from sulphate salts.
Claim 5
Dependent Claim
26 words
An electrolyte as claimed in claim 3 in which the sulphate salts are a mixture of about 0.5 M sodium and about 1 M potassium sulphate.
Claim 6
Dependent Claim
14 words
An electrolyte as claimed in claim 4 in which the buffer is boric acid.
Claim 7
Dependent Claim
14 words
An electrolyte as claimed in claim 3 in which the buffer is boric acid.
Claim 8
Dependent Claim
14 words
An electrolyte as claimed in claim 2 in which the buffer is boric acid.
Claim 9
Dependent Claim
14 words
An electrolyte as claimed in claim 1 in which the buffer is boric acid.
Claim 10
Dependent Claim
89 words
A bath for electroplating chromium comprising an anolyte separated from a catholyte by a perfluorinated cation exchange membrane, and the catholyte consisting of a source of trivalent chromium ions, a complexant, a buffer and a sulphur species selected from the group consisting of thiosulphates, thionates, polythionates and sulfoxylates for promoting chromium deposition, the complexant being selected so that the stability constant K 1 of the reaction between the chromium ions and the complexant is in the range 10 6 <K 1 <10 12 M -1 at about 25° C.
Claim 11
Dependent Claim
89 words
A bath for electroplating chromium comprising an anolyte separated from a catholyte by a perfluorinated cation exchange membrane, and the catholyte consisting of a source of trivalent chromium ions, a complexant, a buffer and a sulphur species selected from the group consisting of thiosulphates, thionates, polythionates and sulfoxylates for promoting chromium deposition, the complexant being selected so that the stability constant K 1 of the reaction between the chromium ions and the complexant is in the range 10 6 <K 1 <10 12 M -1 at about 25° C.
Claim 12
Dependent Claim
14 words
A bath as claimed in claim 9 in which the anolyte comprises sulphate ions.
Claim 13
Dependent Claim
18 words
A bath as claimed in claim 10 including a lead or lead alloy anode immersed in said anolyte.
Claim 14
Dependent Claim
18 words
A bath as claimed in claim 9 including a lead or lead alloy anode immersed in said anolyte.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-05-15 | 1987-11-14 | 1988-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-15 | 1991-11-14 | 1992-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-15 | 1995-11-14 | 1996-05-15 | $7700.00 | Window Closed / Lapsed |