Patent US4394223A successfully refreshed from Google Patents.
US4394223A
Expired / Lapsed
US
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Tin and gold plating process
Assignee: United States Department of the Air Force
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Filing: 1981-10-06
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Granted: 1983-07-19
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Expires: 2001-10-06
Abstract
Abstract A process used for plating a substrate in which the etching of the substrate's copper cladding is terminated early leaving a thin layer of copper. Resist material is then selectively placed upon this thin layer of copper in such a manner that will result in those areas of the circuit to be electroplated being connected. Etching is then resumed to completion, resulting in electrical isolation of those portions of the circuit that are not to be electroplated. Gold electroplating followed by electroless tin plating of the remainder of the circuit can then be performed followed by a final etching to remove the electrical shorts.
Inventors
- 👤 R. Dean Hall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:12
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/22; H05K3/24; H05K3/243; C; C25; C25D; C25D5/00; C25D5/02; H05K3/02; H05K3/06; H05K3/061; H05K2201/00; H05K2201/03; H05K2201/0332; H05K2201/0388; H05K2201/0391; H05K2203/00; H05K2203/03; H05K2203/0369; H05K2203/05; H05K2203/0562; H05K2203/0574; H05K2203/058; H05K2203/0597; H05K2203/07; H05K2203/0703; H05K2203/072; H05K2203/0723; H05K2203/073; H05K2203/14; H05K2203/1476; H05K3/062; H05K3/241; H05K3/242; H05K3/40; H05K3/4007
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
198 words
A method for plating two metals onto a copper clad substrate comprising the steps of: a. defining, by utilizing photoresist material, a circuit pattern on the copper cladding which results in protected copper and unprotected copper; b. etching away the unprotected copper until only a thin layer of copper remains; c. applying resistive material on selected areas of the thin layer of copper in such a manner that first portions of the circuitry to be plated with a first metal are connected to one another via the resistive material while other portions of the circuitry not to be plated with said first metal are not connected via the resistive material to said first portion; d. etching away to completion the unprotected copper and then removing all photoresist and resistive material; e. applying resistive material to said selected areas of copper in order to protect them from plating; f. electroplating said first portions of the circuitry with said first metal; g. electroless plating said other portions of the circuit with a second metal by immersing the entire substrate in a plating bath; and h. removing all resistive material and then etching away the remainder of the thin copper layer.
Claim 2
Independent Claim
198 words
A method for plating two metals onto a copper clad substrate comprising the steps of: a. defining, by utilizing photoresist material, a circuit pattern on the copper cladding which results in protected copper and unprotected copper; b. etching away the unprotected copper until only a thin layer of copper remains; c. applying resistive material on selected areas of the thin layer of copper in such a manner that first portions of the circuitry to be plated with a first metal are connected to one another via the resistive material while other portions of the circuitry not to be plated with said first metal are not connected via the resistive material to said first portion; d. etching away to completion the unprotected copper and then removing all photoresist and resistive material; e. applying resistive material to said selected areas of copper in order to protect them from plating; f. electroplating said first portions of the circuitry with said first metal; g. electroless plating said other portions of the circuit with a second metal by immersing the entire substrate in a plating bath; and h. removing all resistive material and then etching away the remainder of the thin copper layer.
Claim 3
Dependent Claim
28 words
The method of claim 1, wherein a further step consists of tinning sidewalls of said first portion adjacent to said selected areas where the resistive material was removed.
Claim 4
Dependent Claim
11 words
The method of claim 2, wherein said first metal is gold.
Claim 5
Dependent Claim
11 words
The method of claim 3, wherein said second metal is tin.
Claim 6
Dependent Claim
36 words
The method of claim 1 or 4, wherein a further step between steps (f) and (g) consists of applying resistive material to said first metal in order to protect it from plating by said second metal.
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) | 1986-07-18 | 1987-01-17 | 1987-07-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-18 | 1991-01-17 | 1991-07-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-18 | 1995-01-17 | 1995-07-19 | $7700.00 | Window Closed / Lapsed |