US5501761A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for stripping conformal coatings from circuit boards
Assignee: AT&T Inc
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Filing: 1994-10-18
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Granted: 1996-03-26
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Expires: 2014-10-18
Abstract
Abstract In preparation for removing a protective adherent covercoat from a circuit board that is to be repaired, the surface integrity of the coating is altered (for example, by making incisions therein). Subsequently, the coated circuit board is subjected to supercritical carbon dioxide in a processing chamber. Following this process, the coating is easily lifted from the board.
Inventors
- 👤 Jeffrey J. Evans
- 👤 Leslie A. Guth
- 👤 Urmi Ray
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:23
CPC Classifications
B; B29; B29C; B29C63/00; B29C63/0004; B29C63/0013; H; H05; H05K; H05K3/00; H05K3/22; H05K3/28; H05K3/284; B29C2793/00; B29L; B29L2031/00; B29L2031/34; B29L2031/3425; Y; Y10; Y10S; Y10S156/00; Y10S156/918; Y10S156/919; Y10S156/922; Y10T; Y10T156/00; Y10T156/11; Y10T156/19; Y10T29/00; Y10T29/49; Y10T29/49718; Y10T29/49721; Y10T29/49723; Y10T29/49725; Y10T29/49726; Y10T29/49815; Y10T29/49821
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
36 words
A method for removing a conformal coating from a circuit board, said method comprising the steps of locally thinning said coating, and then subjecting said coated circuit board in a processing chamber to supercritical carbon dioxide.
Claim 2
Independent Claim
36 words
A method for removing a conformal coating from a circuit board, said method comprising the steps of locally thinning said coating, and then subjecting said coated circuit board in a processing chamber to supercritical carbon dioxide.
Claim 3
Dependent Claim
19 words
A method as in claim 1 wherein said thinning step comprises forming at least one incision in said coating.
Claim 4
Dependent Claim
43 words
A method as in claim 2 wherein carbon dioxide is introduced into said chamber, the pressure within said chamber is established between 1073 and 5000 pounds per square inch and the temperature within said chamber is established between 31 and 70 degrees Celsius.
Claim 5
Dependent Claim
30 words
A method as in claim 3 wherein the pressure within said chamber is established at 1500 pounds per square inch and the temperature therein is established at 40 degrees Celsius.
Claim 6
Dependent Claim
14 words
A method as in claim 4 wherein said coating comprises a high-molecular-weight polymer material.
Claim 7
Dependent Claim
16 words
A method as in claim 2 wherein said incisions are made by a mechanical cutting tool.
Claim 8
Dependent Claim
15 words
A method as in claim 6 wherein said mechanical cutting tool comprises a razor knife.
Claim 9
Dependent Claim
15 words
A method as in claim 2 wherein said incisions are made by a laser beam.
Claim 10
Dependent Claim
17 words
A method as in claim 8 wherein said incisions are made by a programmed scanning laser beam.
Claim 11
Dependent Claim
24 words
A method as in claim 2 wherein the depths of the incisions made in said coating are less than the thickness of said coating.
Claim 12
Dependent Claim
19 words
A method as in claim 2 wherein said incisions are made only in a localized portion of said coating.
Claim 13
Dependent Claim
24 words
A method as in claim 4 wherein the coated circuit board is subjected to supercritical carbon dioxide in said chamber for about 45 minutes.
Claim 14
Dependent Claim
26 words
A method as in claim 12 wherein, after the circuit board is removed from said processing chamber, the coating is lifted from the board with tweezers.
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) | 1999-03-26 | 1999-09-25 | 2000-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-03-26 | 2003-09-25 | 2004-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-03-26 | 2007-09-25 | 2008-03-26 | $7700.00 | Window Closed / Lapsed |