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Patent US4787957A successfully refreshed from Google Patents.
US4787957A
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Desmear and etchback using NF3 /O2 gas mixtures
Assignee: Versum Materials US LLC
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Filing: 1987-09-25
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Granted: 1988-11-29
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Expires: 2007-09-25
Abstract
Abstract The present invention is directed to a method for plasma desmear and etchback of epoxy and polyimide materials from a multilayered or double sided printed circuit board using a plasma gas composition in the range of 20-45% NF 3 , the remainder being O 2 .
Inventors
- 👤 John A. Barkanic
- 👤 Donna M. Reynolds
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:23
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/46; C; C09; C09K; C09K13/00; C09K13/04; C09K13/08; H05K3/0011; H05K3/0055; H05K3/10; H05K3/18; H05K2203/00; H05K2203/09; H05K2203/095
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
96 words
In a method for desmearing printed circuit boards using a plasma gas desmearing medium produced between a pair of electrodes in an evacuated chamber wherein the material being desmeared is selected from the group consisting of epoxy and polyimide, the improvement comprising desmearing with a plasma comprising a gas mixture of 20-45% NF 3 the remainder being O 2 wherein the chamber is evacuated to a pressure in the range of 1000 to 3000 milli-Torr, and wherein the power density used to create the plasma is in the range of 0.08 to 0.25 wat/cm 2 .
Claim 2
Dependent Claim
96 words
In a method for desmearing printed circuit boards using a plasma gas desmearing medium produced between a pair of electrodes in an evacuated chamber wherein the material being desmeared is selected from the group consisting of epoxy and polyimide, the improvement comprising desmearing with a plasma comprising a gas mixture of 20-45% NF 3 the remainder being O 2 wherein the chamber is evacuated to a pressure in the range of 1000 to 3000 milli-Torr, and wherein the power density used to create the plasma is in the range of 0.08 to 0.25 wat/cm 2 .
Claim 3
Dependent Claim
12 words
The method of claim 1 wherein the material being desmeared is epoxy.
Claim 4
Dependent Claim
18 words
The method of claim 1 wherein the temperature of the plasma is in the range of 80°-140° C.
Claim 5
Dependent Claim
15 words
The method of claim 1 wherein the temperature of the plasma is approximately 100° C.
Claim 6
Dependent Claim
21 words
The method of claim 1 wherein the gas mixture comprises 25 to 40% NF 3 the remainder being O 2 .
Claim 7
Dependent Claim
19 words
The method of claim 1 wherein the gas mixture comprises approximately 35% NF 3 and 65% O 2 .
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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) | 1991-11-29 | 1992-05-30 | 1992-11-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-29 | 1996-05-30 | 1996-11-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-29 | 2000-05-30 | 2000-11-29 | $7700.00 | Window Closed / Lapsed |