US4089704A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removal of RTV silicon rubber encapsulants
Assignee: AT&T Inc
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Filing: 1976-12-27
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Granted: 1978-05-16
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Expires: 1996-12-27
Abstract
Abstract Disclosed is a method of removing silicone rubber encapsulating material from micro-electronic circuits. The encapsulant is broken down molecularly and removed by a solution of tetramethyl-ammonium hydroxide which is diluted with an alcohol such as 2-propanol. It was found that this stripping solution causes minimal swelling of the encapsulant and leaves no significant residue which cannot be removed by standard rinsing.
Inventors
- 👤 John Herbert Heiss, Jr.
- 👤 John Robert Wylie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:42
CPC Classifications
C; C08; C08J; C08J11/00; C08J11/04; C08J11/10; C08J11/18; C08J11/28; H; H10; H10W; H10W74/00; H10W74/01; C08J2383/00; C08J2383/04; H05; H05K; H05K3/00; H05K3/22; H05K3/28; H05K3/288; Y; Y02; Y02W; Y02W30/00; Y02W30/50; Y02W30/62
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
39 words
In a process for fabricating circuits formed in an insulating substrate, the method of removing silicone rubber encapsulants formed over said circuit comprising the step of applying to said encapsulant a solution consisting of tetramethylammonium hydroxide, methanol and 2-propanol.
Claim 2
Dependent Claim
39 words
In a process for fabricating circuits formed in an insulating substrate, the method of removing silicone rubber encapsulants formed over said circuit comprising the step of applying to said encapsulant a solution consisting of tetramethylammonium hydroxide, methanol and 2-propanol.
Claim 3
Dependent Claim
18 words
The method according to claim 1 wherein the temperature of the solution is within the range 25°-55° C.
Claim 4
Dependent Claim
25 words
The method according to claim 1 wherein the concentration by volume of tetramethylammonium hydroxide and methanol to 2-propanol lies within the range 1:10 to 1:20.
Claim 5
Dependent Claim
18 words
The method according to claim 2 wherein the temperature of the solution is within the range 36°-40° C.
Claim 6
Dependent Claim
29 words
The method according to claim 1 wherein the circuit is successively immersed in different baths of said solution and thereafter rinsed by immersing in a material comprising isopropyl alcohol.
Claim 7
Dependent Claim
154 words
In a process for fabricating circuits formed on an insulating substrate, the method of removing silicone rubber encapsulants comprising siloxanes with methoxy end groups formed on said circuit comprising the steps of: immersing the circuit in a first solution consisting of tetramethylammonium hydroxide, methanol and 2-propanol with a concentration by volume of tetramethylammonium hydroxide and methanol to 2-propanol within the range 1:10 to 1:20 at a temperature within the range 36°-40° C for a period of time within the range 2-6 hours; removing said circuit from said first solution and immersing in a second solution of the same composition at a temperature within the range 36°-40° C for a period of time within the range 1-2 hours in order to remove any residue remaining after immersion in said first solution; and removing said circuit from said second solution and immersing in third and fourth solutions comprising isopropyl alcohol in order to rinse said circuit.
Claim 8
Dependent Claim
154 words
In a process for fabricating circuits formed on an insulating substrate, the method of removing silicone rubber encapsulants comprising siloxanes with methoxy end groups formed on said circuit comprising the steps of: immersing the circuit in a first solution consisting of tetramethylammonium hydroxide, methanol and 2-propanol with a concentration by volume of tetramethylammonium hydroxide and methanol to 2-propanol within the range 1:10 to 1:20 at a temperature within the range 36°-40° C for a period of time within the range 2-6 hours; removing said circuit from said first solution and immersing in a second solution of the same composition at a temperature within the range 36°-40° C for a period of time within the range 1-2 hours in order to remove any residue remaining after immersion in said first solution; and removing said circuit from said second solution and immersing in third and fourth solutions comprising isopropyl alcohol in order to rinse said circuit.
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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) | 1981-05-15 | 1981-11-14 | 1982-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-15 | 1985-11-14 | 1986-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-15 | 1989-11-14 | 1990-05-16 | $7700.00 | Window Closed / Lapsed |