US4169026A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Etchant for electrolytic etching of a ferrite for a magnetic head and method of producing a magnetic head
Assignee: Panasonic Holdings Corp
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Filing: 1978-07-10
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Granted: 1979-09-25
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Expires: 1998-07-10
Abstract
Abstract An etchant comprising an electrolytic liquid which comprises sulfuric acid as a main component and water in such amount that the weight ratio of sulfuric acid to water is between 9:1 and 2:1. The ferrite surface having been electrolytically etched by using this etchant is smooth. Thus, this etchant makes it possible to etch a ferrite to a large depth, and thereby easily shape a ferrite by electrolytic etching, e.g. to define the track width of a magnetic head.
Inventors
- 👤 Tatsuro Kikuchi
- 👤 Kenichi Fujimura
- 👤 Hyogo Hirohata
- 👤 Tetsuo Hino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 01:46
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/12; H01F1/34; C; C25; C25F; C25F3/00; C25F3/02; G; G11; G11B; G11B5/00; G11B5/127; G11B5/187; G11B5/193
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
147 words
A method of producing a magnetic head, comprising: preparing a pair of ferrite blocks joined together by glass to form a magnetic gap therebetween; coating an etching resist on one surface of the joined pair of ferrite blocks to leave at least a part of the joint portion between the two ferrite blocks on said one surface uncoated with the etching resist; contacting the ferrite blocks with an etchant comprising an electrolytic liquid which comprises sulfuric acid as a main component and water in such amount that the weight ratio of sulfuric acid to water is between 9:1 and 2:1, so as to electrolytically etch said uncoated part of the joint portion of the two ferrite blocks on said one surface to partially remove the joint portion of the ferrite blocks and thereby define a magnetic track width of the magnetic head; and removing the etching resist.
Claim 2
Independent Claim
147 words
A method of producing a magnetic head, comprising: preparing a pair of ferrite blocks joined together by glass to form a magnetic gap therebetween; coating an etching resist on one surface of the joined pair of ferrite blocks to leave at least a part of the joint portion between the two ferrite blocks on said one surface uncoated with the etching resist; contacting the ferrite blocks with an etchant comprising an electrolytic liquid which comprises sulfuric acid as a main component and water in such amount that the weight ratio of sulfuric acid to water is between 9:1 and 2:1, so as to electrolytically etch said uncoated part of the joint portion of the two ferrite blocks on said one surface to partially remove the joint portion of the ferrite blocks and thereby define a magnetic track width of the magnetic head; and removing the etching resist.
Claim 3
Dependent Claim
32 words
A method of producing a magnetic head according to claim 1, wherein said one surface of the joined ferrite blocks is the surface perpendicular to the working surface of the magnetic head.
Claim 4
Dependent Claim
31 words
A method of producing a magnetic head according to claim 1, wherein said one surface of the joined ferrite blocks is the surface involving the working surface of the magnetic head.
Claim 5
Dependent Claim
47 words
A method of producing a magnetic head according to claim 1 wherein said electrolytic liquid additionally contains 1/6 to 3 weight parts of an additive selected from the group consisting of glycerine, ethyleneglycol, dioxane and triethylenetetramine on the basis of one weight part of said electrolytic liquid.
Claim 6
Independent Claim
99 words
A method of producing a magnetic head, comprising the steps of: (a) preparing a pair of ferrite blocks by grinding a surface on each of said ferrite blocks, a deformed layer being produced on each of said surfaces by said grinding step; (b) electrolytically etching each of said surfaces in an electrolytic liquid which comprises sulfuric acid as a main component and water in such amount that the weight ratio of sulfuric acid to water is between 9:1 and 2:1, so as to remove said deformed layer; and (c) joining said ferrite blocks with said surfaces facing each other.
Claim 7
Independent Claim
99 words
A method of producing a magnetic head, comprising the steps of: (a) preparing a pair of ferrite blocks by grinding a surface on each of said ferrite blocks, a deformed layer being produced on each of said surfaces by said grinding step; (b) electrolytically etching each of said surfaces in an electrolytic liquid which comprises sulfuric acid as a main component and water in such amount that the weight ratio of sulfuric acid to water is between 9:1 and 2:1, so as to remove said deformed layer; and (c) joining said ferrite blocks with said surfaces facing each other.
Claim 8
Dependent Claim
50 words
A method of producing a smooth surface on a ferrite according to claim 5 wherein said electrolytic liquid additionally contains 1/6 to 3 weight parts of an additive selected from the group consisting of glycerine, ethyleneglycol, dioxane and triethylenetetramine on the basis of one weight part of said electrolytic liquid.
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) | 1982-09-24 | 1983-03-26 | 1983-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-09-24 | 1987-03-26 | 1987-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-09-24 | 1991-03-26 | 1991-09-25 | $7700.00 | Window Closed / Lapsed |