Patent US4497687A successfully refreshed from Google Patents.
US4497687A
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Aqueous process for etching cooper and other metals
Assignee: PSI Star Inc
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Filing: 1983-12-20
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Granted: 1985-02-05
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Expires: 2003-12-20
Abstract
Abstract Nitrogen dioxide process for etching copper and other metals, using water as a catalyst/solvent. In one disclosed embodiment, a film of water is formed on the surface of the metal, and the water-covered metal is exposed to gaseous NO 2 to dissolve the metal. In another embodiment, the metal is exposed to an aqueous solution of NO 2 or HNO 3 in water, either by immersion or by spraying, to remove the metal.
Inventors
- 👤 Norvell J. Nelson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:24
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/10; C23F1/12; C23F1/14; C23F1/16; H; H05; H05K; H05K3/00; H05K3/02; H05K3/06; H05K3/067
Claims Analysis
Total Claims: 47
Claim 1
Independent Claim
37 words
In a process for etching copper, the steps of: forming a film of water on the surface of the copper, and exposing the water-covered copper to gaseous NO 2 for a time sufficient to dissolve the copper.
Claim 2
Dependent Claim
37 words
In a process for etching copper, the steps of: forming a film of water on the surface of the copper, and exposing the water-covered copper to gaseous NO 2 for a time sufficient to dissolve the copper.
Claim 3
Dependent Claim
46 words
The process of claim 1 wherein the film of water is formed on the copper by applying a mixture of water and an additive which serves both as a surfactant and as an inhibitor of etching in a direction parallel to the surface of the copper.
Claim 4
Dependent Claim
11 words
The process of claim 2 wherein the additive comprises a polymer.
Claim 5
Dependent Claim
23 words
The process of claim 3 wherein the polymer is selected from the group consisting of a water-soluble polyacrylamide, a carboxymethyl-cellulose, and poly(acrylic acid).
Claim 6
Dependent Claim
13 words
The process of claim 3 wherein the polymer comprises a cationic water-soluble polyacrylamide.
Claim 7
Dependent Claim
12 words
The process of claim 2 wherein the additive is a cationic surfactant.
Claim 8
Dependent Claim
73 words
In a process for removing copper from a printed circuit board having a substrate beneath the copper and etch resist material covering a portion of the copper to be retained, contacting the board with an aqueous solution of NO 2 or HNO 3 , and including a sufficient quantity of a dissolved copper salt in the solution to prevent attack of the substrate or the etch resist material as the copper is removed.
Claim 9
Dependent Claim
73 words
In a process for removing copper from a printed circuit board having a substrate beneath the copper and etch resist material covering a portion of the copper to be retained, contacting the board with an aqueous solution of NO 2 or HNO 3 , and including a sufficient quantity of a dissolved copper salt in the solution to prevent attack of the substrate or the etch resist material as the copper is removed.
Claim 10
Dependent Claim
32 words
The process of claim 7 wherein the copper salt is selected from the group consisting of Cu(NO 3 ) 2 , CuSO 4 , copper (II) tetrafluoroborate, CuCl 2 and combinations thereof.
Claim 11
Dependent Claim
42 words
catalyst/solvent for use in the etching of copper with gaseous NO 2 , comprising a mixture of water and an additive which serves as a surfactant and as an inhibitor of etching in a direction parallel to the surface of the copper.
Claim 12
Dependent Claim
42 words
catalyst/solvent for use in the etching of copper with gaseous NO 2 , comprising a mixture of water and an additive which serves as a surfactant and as an inhibitor of etching in a direction parallel to the surface of the copper.
Claim 13
Dependent Claim
11 words
The catalyst/solvent of claim 9 wherein the additive comprises a polymer.
Claim 14
Dependent Claim
24 words
The catalyst/solvent of claim 10 wherein the polymer is selected from the group consisting of a water-soluble polyacrylamide, a carboxymethyl-cellulose, and poly (acrylic acid).
Claim 15
Dependent Claim
13 words
The catalyst/solvent of claim 10 wherein the polymer comprises a cationic water-soluble polyacrylamide.
Claim 16
Dependent Claim
42 words
In a process for etching a metal on a substrate: exposing the metal to an aqueous solution of NO 2 or HNO 3 containing a sufficient quantity of a metal nitrate to prevent etching of the substrate as the metal is dissolved.
Claim 17
Dependent Claim
42 words
In a process for etching a metal on a substrate: exposing the metal to an aqueous solution of NO 2 or HNO 3 containing a sufficient quantity of a metal nitrate to prevent etching of the substrate as the metal is dissolved.
Claim 18
Dependent Claim
25 words
The process of claim 13 wherein the metal is selected from the group consisting of copper, vanadium, manganese, iron, cobalt, nickel, palladium, and alloys thereof.
Claim 19
Dependent Claim
18 words
The process of claim 13 wherein the nitrate contained in the solution is Cu(NO 3 ) 2 .
Claim 20
Dependent Claim
20 words
The process of claim 13 wherein the nitrate contained in the solution is a nitrate of the metal being etched.
Claim 21
Dependent Claim
87 words
In a process for etching copper having a lead-tin solder mask covering a portion thereof, the steps of: forming a film of water on the surface of the copper by applying an aqueous solution containing a surfactant, an additive which inhibits etching of the copper at a direction parallel to the surface and a phosphate which prevents etching of the solder mask, and exposing the water-covered copper to gaseous NO 2 for a time sufficient to dissolve the copper which is not covered by the solder mask.
Claim 22
Dependent Claim
87 words
In a process for etching copper having a lead-tin solder mask covering a portion thereof, the steps of: forming a film of water on the surface of the copper by applying an aqueous solution containing a surfactant, an additive which inhibits etching of the copper at a direction parallel to the surface and a phosphate which prevents etching of the solder mask, and exposing the water-covered copper to gaseous NO 2 for a time sufficient to dissolve the copper which is not covered by the solder mask.
Claim 23
Dependent Claim
16 words
The process of claim 17 wherein the aqueous solution contains both phosphoric acid and another phosphate.
Claim 24
Dependent Claim
66 words
In a process for removing copper from a printed circuit board having a substrate beneath the copper and a lead-tin solder mask covering a portion of the copper, contacting the board with an aqueous solution of NO 2 or HNO 3 , a sufficient quantity of a dissolved copper salt to prevent etching of the substrate, and a phosphate to prevent etching of the solder mask.
Claim 25
Dependent Claim
66 words
In a process for removing copper from a printed circuit board having a substrate beneath the copper and a lead-tin solder mask covering a portion of the copper, contacting the board with an aqueous solution of NO 2 or HNO 3 , a sufficient quantity of a dissolved copper salt to prevent etching of the substrate, and a phosphate to prevent etching of the solder mask.
Claim 26
Dependent Claim
15 words
The process of claim 19 wherein the aqueous solution contains phosphoric acid and another phosphate.
Claim 27
Dependent Claim
39 words
A catalyst/solvent for use in the etching of copper with gaseous NO 2 , comprising a mixture of water, a phosphate, a surfactant and an additive which inhibits etching in a direction parallel to the surface of the copper.
Claim 28
Dependent Claim
39 words
A catalyst/solvent for use in the etching of copper with gaseous NO 2 , comprising a mixture of water, a phosphate, a surfactant and an additive which inhibits etching in a direction parallel to the surface of the copper.
Claim 29
Dependent Claim
11 words
The catalyst/solvent of claim 21 including phosphoric acid and another phosphate.
Claim 30
Dependent Claim
41 words
In a process of etching a metal having a lead-tin solder mask covering a portion thereof: exposing the metal to an aqueous solution of NO 2 or HNO 3 containing a metal nitrate and a phosphate to dissolve the exposed metal.
Claim 31
Dependent Claim
41 words
In a process of etching a metal having a lead-tin solder mask covering a portion thereof: exposing the metal to an aqueous solution of NO 2 or HNO 3 containing a metal nitrate and a phosphate to dissolve the exposed metal.
Claim 32
Dependent Claim
15 words
The process of claim 23 wherein the aqueous solution contains phosphoric acid and another phosphate.
Claim 33
Dependent Claim
82 words
In a process for removing copper from a printed circuit board having a substrate beneath the copper and etch resist material covering a portion of the copper to be retained, contacting the board with an aqueous solution of NO 2 or HNO 3 , a sufficient quantity of a dissolved copper salt to prevent attack of the substrate or the etch resist material as the copper is removed, and a polymer additive which prevents undercutting of the copper as it is etched.
Claim 34
Dependent Claim
82 words
In a process for removing copper from a printed circuit board having a substrate beneath the copper and etch resist material covering a portion of the copper to be retained, contacting the board with an aqueous solution of NO 2 or HNO 3 , a sufficient quantity of a dissolved copper salt to prevent attack of the substrate or the etch resist material as the copper is removed, and a polymer additive which prevents undercutting of the copper as it is etched.
Claim 35
Dependent Claim
24 words
The process of claim 25 wherein the polymer is selected from the group consisting of a water-soluble polyacrylamide, a carboxymethyl-cellulose, and poly (acrylic acid).
Claim 36
Dependent Claim
13 words
The process of claim 25 wherein the polymer comprises a cationic water-soluble polyacrylamide.
Claim 37
Dependent Claim
50 words
The process of claim 25 wherein the aqueous solution comprises 0.5-2.0 units by weight of 10%-100% HNO 3 in water, 2.5-10 units by weight of 0.1-1.0% solution of a water-soluble acrylamide polymer in water, and 11-44 units by weight of a 10-60% solution of Cu(NO 3 ) 2 in water.
Claim 38
Dependent Claim
32 words
In an aqueous solution for etching copper: NO 2 or HNO 3 , a dissolved copper salt, a surfactant and an additive to inhibit undercutting of the copper as it is etched.
Claim 39
Dependent Claim
32 words
In an aqueous solution for etching copper: NO 2 or HNO 3 , a dissolved copper salt, a surfactant and an additive to inhibit undercutting of the copper as it is etched.
Claim 40
Dependent Claim
14 words
The solution of claim 29 wherein the surfactant and the additive are a polymer.
Claim 41
Dependent Claim
24 words
The solution of claim 30 wherein the polymer is selected from a group consisting of a water-soluble polyacrylamide, a carboxymethyl-cellulose, and poly (acrylic acid).
Claim 42
Dependent Claim
12 words
The solution of claim 29 wherein the solution also contains a phosphate.
Claim 43
Dependent Claim
15 words
The solution of claim 29 wherein the solution also contains phosphoric acid and another phosphate.
Claim 44
Dependent Claim
72 words
In a process for removing a selected portion of copper from a printed circuit board having a substrate beneath the copper and a mask covering another portion of the copper: contacting the board with an aqueous solution of NO 2 or HNO 3 , a sufficient amount of a dissolved copper salt to prevent etching of the substrate, a surfactant and an additive which inhibits undercutting of the copper beneath the mask.
Claim 45
Dependent Claim
72 words
In a process for removing a selected portion of copper from a printed circuit board having a substrate beneath the copper and a mask covering another portion of the copper: contacting the board with an aqueous solution of NO 2 or HNO 3 , a sufficient amount of a dissolved copper salt to prevent etching of the substrate, a surfactant and an additive which inhibits undercutting of the copper beneath the mask.
Claim 46
Dependent Claim
21 words
The process of claim 34 wherein the mask comprises a lead-tin solder mask, and the aqueous solution also includes a phosphate.
Claim 47
Dependent Claim
15 words
The process of claim 35 wherein the solution contains both phosphoric acid and another phosphate.
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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) | 1988-02-05 | 1988-08-06 | 1989-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-05 | 1992-08-06 | 1993-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-05 | 1996-08-06 | 1997-02-05 | $7700.00 | Window Closed / Lapsed |