US4420367A
Expired / Lapsed
US
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Method for etching a recrystallized aluminum foil for electrolytic capacitors
Assignee: Siemens AG
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Filing: 1982-04-15
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Granted: 1983-12-13
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Expires: 2002-04-15
Abstract
Abstract Method for etching a recrystallized aluminum foil for electrolytic capacitors by carrying out an electrolytic tunnel formation in a first etching stage, characterized by the feature that the further etching for tunnel enlargement takes place chemically in one or several etching stages.
Inventors
- 👤 Gunter Locher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:56
CPC Classifications
H; H01; H01G; H01G9/00; H01G9/004; H01G9/04; H01G9/048; H01G9/055; C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/16; C23F1/20; C25; C25F; C25F3/00; C25F3/02; C25F3/04
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
71 words
Method for etching a recrystallized aluminum foil for electrolytic capacitors which comprises subjecting the recrystallized aluminum foil in a first etching stage to electrolytic tunnel formation to form a tunnel structure in the aluminum, and subsequently subjecting the aluminum foil with the tunnel structure from the first etching stage in at least one further non-electrolytic etching stage in a solution free of halogen ions to effect tunnel enlargement by chemical etching.
Claim 2
Dependent Claim
71 words
Method for etching a recrystallized aluminum foil for electrolytic capacitors which comprises subjecting the recrystallized aluminum foil in a first etching stage to electrolytic tunnel formation to form a tunnel structure in the aluminum, and subsequently subjecting the aluminum foil with the tunnel structure from the first etching stage in at least one further non-electrolytic etching stage in a solution free of halogen ions to effect tunnel enlargement by chemical etching.
Claim 3
Dependent Claim
16 words
Method according to claim 1, wherein the tunnel formation is carried out with constant anode potential.
Claim 4
Dependent Claim
27 words
Method according to claim 1, wherein the tunnel formtion is carried out with a current density which approaches the current density course in time for potentiostatic etching.
Claim 5
Dependent Claim
35 words
Method according to claim 1 or claim 2 or claim 3, wherein the further non-electrolytic etching takes place in said solution free of halogen ions maintained within the range of 40° C. to 95° C.
Claim 6
Dependent Claim
23 words
Method according to claim 1 or claim 2 or claim 3, wherein the further non-electrolytic etching takes place with solutions containing nitrate ions.
Claim 7
Dependent Claim
37 words
Method according to claim 1 or claim 2 or claim 3, wherein the further non-electrolytic etching takes place with solutions containing a nitrate selected from the group consisting of HNO 3 and Al(NO 3 ) 3 .
Claim 8
Dependent Claim
66 words
Method according to claim 1 or claim 2 or claim 3, wherein the further non-electrolytic etching takes place with solutions containing a nitrate selected from the group consisting of HNO 3 and Al(NO 3 ) 3 , and in which the concentration of the solutions are 1% by weight to 30% by weight HNO 3 and 0.2 mol/liter to 2 mol/liter Al(NO 3 ) 3 .
Claim 9
Dependent Claim
25 words
Method according to claim 1, wherein the further non-electrolytic etching is carried out in several baths with Al dissolution rates which are reduced in steps.
Claim 10
Dependent Claim
22 words
Method according to claim 8, wherein the stepwise reduction of the Al dissolution rate is accomplished with bath temperatures reduced in steps.
Claim 11
Dependent Claim
22 words
Method according to claim 8, wherein the stepwise reduction of the Al dissolution rate is accomplished with both concentrations reduced in steps.
References Cited (Backward Citations)
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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) | 1986-12-12 | 1987-06-13 | 1987-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-12 | 1991-06-13 | 1991-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-12 | 1995-06-13 | 1995-12-13 | $7700.00 | Window Closed / Lapsed |