US4238300A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gold electroplating process
Assignee: AT&T Inc
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Filing: 1979-05-25
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Granted: 1980-12-09
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Expires: 1999-05-25
Abstract
Abstract Electrolytic deposition of gold results in the formation of undesirable reducible gold III species in the electroplating bath which interfere with the current efficiency and make the prediction of gold thickness based on applied current impossible. Addition of a small quantity of hypophosphorous acid to the plating bath when the current efficiency has dropped below a certain minimum, chemically reduces accumulated gold III species and scavenges dissolved oxygen. Thus, the current efficiency is restored to about 100%. The hypophosphorous acid treatment is particularly advantageous in a phosphate buffered bath because no foreign ions are introduced into the solution.
Inventors
- 👤 Kei Yoshida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:12
CPC Classifications
C; C25; C25D; C25D3/00; C25D3/02; C25D3/48
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
42 words
A method of manufacturing an article by steps comprising electrolytically depositing gold from a gold plating bath onto said article, characterized by adding hypophosphorous acid to said bath, with the pH of said bath being in the range of 6 to 10.
Claim 2
Independent Claim
42 words
A method of manufacturing an article by steps comprising electrolytically depositing gold from a gold plating bath onto said article, characterized by adding hypophosphorous acid to said bath, with the pH of said bath being in the range of 6 to 10.
Claim 3
Dependent Claim
36 words
The method of claim 1 further characterized in that about 0.06-0.10 M (Vol.) hypophosphorous acid is added and said bath is heated to a temperature of at least 70 degrees C. for at least three hours.
Claim 4
Dependent Claim
41 words
The method of claim 1 further characterized in that said bath comprises an aqueous solution of a gold alkali metal cyanide and at least one buffer selected from the group of alkali metal and alkaline earth metal primary and secondary phosphates.
Claim 5
Independent Claim
30 words
The method of claims 1, 2, or 3 further characterized by monitoring the accumulation of gold III species and adding said hypophosphorous acid when said accumulation reaches a predetermined value.
Claim 6
Independent Claim
32 words
The method of claims 1, 2, or 3 further characterized by monitoring the current efficiency of said bath and adding said hypophosphorous acid when said current efficiency reaches a predetermined minimum value.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-09 | 1984-06-09 | 1984-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-09 | 1988-06-09 | 1988-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-09 | 1992-06-09 | 1992-12-09 | $7700.00 | Window Closed / Lapsed |