US4424241A
Expired / Lapsed
US
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Electroless palladium process
Assignee: AT&T Inc
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Filing: 1982-09-27
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Granted: 1984-01-03
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Expires: 2002-09-27
Abstract
Abstract A process is described for electrolessly plating palladium metal on a variety of surfaces including palladium surfaces. The process involves use of a special electroless plating bath which is sufficiently stable for practical commercial use and yields excellent plating results. The plating bath contains a palladium salt and organic ligand. A narrow class of reducing agents is used including formaldehyde. The bath is made acid generally by the addition of nitric acid or hydrochloric acid. The process yields plating rates of about 6 microinches per minute and plating thicknesses in excess of 1 micrometer.
Inventors
- 👤 Joseph A. Abys
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 14:54
CPC Classifications
C; C23; C23C; C23C18/00; C23C18/16; C23C18/31; C23C18/42; C23C18/44
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
99 words
A process for electrolessly plating palladium on a catalytically active surface comprising the step of wetting said surface with an electroless palladium plating bath comprising reducing agent characterized in that the electroless palladium plating bath comprises a. source of palladium in the concentration range from 0.001 to 1.0 molar; b. sufficient acid so the pH of the bath is less than 2, and; c. reducing agent consisting essentially of at least one compound selected from the group consisting of formaldehyde, formic acid, hypophosphoric acid and trimethoxyborohydride, said reducing agent present in the concentration range from 0.001 to 2.0 molar.
Claim 2
Dependent Claim
99 words
A process for electrolessly plating palladium on a catalytically active surface comprising the step of wetting said surface with an electroless palladium plating bath comprising reducing agent characterized in that the electroless palladium plating bath comprises a. source of palladium in the concentration range from 0.001 to 1.0 molar; b. sufficient acid so the pH of the bath is less than 2, and; c. reducing agent consisting essentially of at least one compound selected from the group consisting of formaldehyde, formic acid, hypophosphoric acid and trimethoxyborohydride, said reducing agent present in the concentration range from 0.001 to 2.0 molar.
Claim 3
Dependent Claim
71 words
The process of claim 1 in which the electroless palladium plating bath additionally comprises organic ligand, said organic ligand consisting essentially of at least one compound selected from the group consisting of monocarboxylic acids with up to 10 carbon atoms, dicarboxylic acids with up to 10 carbon atoms, sulfonic acids with up to 10 carbon atoms, sulfanilic acid and sulfamic acid and the organic has concentration between 0.001 and 1.0 molar.
Claim 4
Dependent Claim
30 words
The process of claim 2 in which the organic ligand consists essentially of at least one compound selected from the group consisting of oxalic acid, tartaric acid and citric acid.
Claim 5
Dependent Claim
16 words
The process of claim 3 in which the concentration range is from 0.1 to 0.5 molar.
Claim 6
Dependent Claim
35 words
The process of claim 1 in which the source of palladium consists essentially of at least one compound selected from the group consisting of palladium chloride, palladium bromide, palladium nitrate, palladium sulfate and palladium hydroxide.
Claim 7
Dependent Claim
26 words
The process of claim 5 in which the concentration range of the source of palladium in terms of metallic palladium is between 0.01 and 0.2 molar.
Claim 8
Dependent Claim
19 words
The process of claim 1 in which the pH of the electroless palladium plating bath is less than 1.5.
Claim 9
Dependent Claim
13 words
The process of claim 7 in which the pH is less than 1.0.
Claim 10
Dependent Claim
23 words
The process of claim 1 in which the acid is selected from the group consisting of nitric acid, hydrochloric acid and sulfuric acid.
Claim 11
Dependent Claim
12 words
The process of claim 1 in which the reducing agent is formaldehyde.
Claim 12
Dependent Claim
18 words
The process of claim 10 in which the concentration of reducing agent is between 0.01 and 1.0 molar.
Claim 13
Dependent Claim
43 words
The process of claim 1 in which the electroless palladium plating bath additionally comprises organic additive, said organic additive consisting essentially of at least one compound selected from the group consisting of saccharin, cumarin, and phenolphthalein with concentration between 0.001 and 0.1 molar.
Claim 14
Dependent Claim
14 words
The process of claim 12 in which the organic additive consists essentially of saccharin.
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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) | 1987-01-02 | 1987-07-04 | 1988-01-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-02 | 1991-07-04 | 1992-01-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-02 | 1995-07-04 | 1996-01-03 | $7700.00 | Window Closed / Lapsed |