Patent US4512862A successfully refreshed from Google Patents.
US4512862A
Expired / Lapsed
US
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Method of making a thin film insulator
Assignee: International Business Machines Corp
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Filing: 1983-08-08
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Granted: 1985-04-23
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Expires: 2003-08-08
Abstract
Abstract In magnetic heads it is often necessary to place conductive films on a ferrite substrate. If the ferrite is conductive, an insulative film is required between the ferrite substrate and the conductive film. A thin insulative film can be formed on a surface of the ferrite substrate by alternately dipping the substrate in solutions containing particles of silica and alumina.
Inventors
- 👤 Eugene B. Rigby
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 09:03
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B41/45; C04B41/50; C04B41/5025; C04B41/52; C04B41/80; C04B41/81; C04B41/85; C04B41/87; C04B41/89; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/12; H01F1/14; H01F1/16; H01F1/18; H01F1/34; H01F1/342; H01F1/344
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
228 words
A process for forming a thin insulative coating on a substrate having an electrical surface charge in an acidic solution comprising the steps of: preparing an up to 5% by weight silica solution containing particles of SiO 2 in the range between 50 Å and 400 Å, said solution having a pH in the range between 2 and 5 and a first charge; preparing an approximately 1% by weight alumina solution containing alumina particles of approximately 50 Å size, said alumina solution having a pH in the range between 2 and 5 and a second charge opposite to said first charge; dipping said substrate into the one of said solutions having a charge opposite to said surface charge and, thereafter, alternately dipping said substrate into said prepared solutions to form at least one layer of particles from each charged solution to thereby form alternate silica and alumina layers on said substrate, said alternating layers being formed until a coating thickness of at least 1000 Å is obtained; and sealing the coated surface of said dipped substrate by (a) heating said substrate, or (b) dipping said substrate in a hydrolized orthosilicate solution, washing said dipped substrate and subsequently heating said substrate to a temperature between 250° to 350° C., or (c) dipping said substrate in a heated sodium silicate solution, washing said dipped substrate and subsequently heating said substrate.
Claim 2
Dependent Claim
228 words
A process for forming a thin insulative coating on a substrate having an electrical surface charge in an acidic solution comprising the steps of: preparing an up to 5% by weight silica solution containing particles of SiO 2 in the range between 50 Å and 400 Å, said solution having a pH in the range between 2 and 5 and a first charge; preparing an approximately 1% by weight alumina solution containing alumina particles of approximately 50 Å size, said alumina solution having a pH in the range between 2 and 5 and a second charge opposite to said first charge; dipping said substrate into the one of said solutions having a charge opposite to said surface charge and, thereafter, alternately dipping said substrate into said prepared solutions to form at least one layer of particles from each charged solution to thereby form alternate silica and alumina layers on said substrate, said alternating layers being formed until a coating thickness of at least 1000 Å is obtained; and sealing the coated surface of said dipped substrate by (a) heating said substrate, or (b) dipping said substrate in a hydrolized orthosilicate solution, washing said dipped substrate and subsequently heating said substrate to a temperature between 250° to 350° C., or (c) dipping said substrate in a heated sodium silicate solution, washing said dipped substrate and subsequently heating said substrate.
Claim 3
Dependent Claim
230 words
A process for forming a thin insulative coating on a conductive ferrite substrate having an electrical surface charge in an acidic solution comprising the steps of: preparing an up to 2% by weight silica solution containing spherical particles of SiO 2 of between about 150 Å and 400 Å, said solution having a pH in the range between 3.5 and 4.5 and a first charge; preparing an approximately 1% by weight alumina solution containing alumina particles of approximately 50 Å size, said alumina solution having a pH in the range between 3 and 5 and a second charge opposite to said first charge; dipping said substrate into the one of said solutions having a charge opposite to said surface charge and, thereafter, alternately dipping said substrate into said prepared solutions to form at least one layer of particles from each charged solution to thereby form alternate silica and alumina layers on said substrate, said alternating layers being formed until a coating thickness of at least 1000 Å is obtained; and sealing the coated surface of said dipped substrate by (a) heating said substrate, or (b) dipping said substrate in a hydrolized orthosilicate solution, washing said dipped substrate and subsequently heating said substrate to a temperature between 250° to 350° C., or (c) dipping said substrate in a heated sodium silicate solution, washing said dipped substrate and subsequently heating said substrate.
Claim 4
Dependent Claim
230 words
A process for forming a thin insulative coating on a conductive ferrite substrate having an electrical surface charge in an acidic solution comprising the steps of: preparing an up to 2% by weight silica solution containing spherical particles of SiO 2 of between about 150 Å and 400 Å, said solution having a pH in the range between 3.5 and 4.5 and a first charge; preparing an approximately 1% by weight alumina solution containing alumina particles of approximately 50 Å size, said alumina solution having a pH in the range between 3 and 5 and a second charge opposite to said first charge; dipping said substrate into the one of said solutions having a charge opposite to said surface charge and, thereafter, alternately dipping said substrate into said prepared solutions to form at least one layer of particles from each charged solution to thereby form alternate silica and alumina layers on said substrate, said alternating layers being formed until a coating thickness of at least 1000 Å is obtained; and sealing the coated surface of said dipped substrate by (a) heating said substrate, or (b) dipping said substrate in a hydrolized orthosilicate solution, washing said dipped substrate and subsequently heating said substrate to a temperature between 250° to 350° C., or (c) dipping said substrate in a heated sodium silicate solution, washing said dipped substrate and subsequently heating said substrate.
Claim 5
Dependent Claim
14 words
A process as defined in claim 1 wherein said substrate is a conductive ferrite.
Claim 6
Dependent Claim
13 words
A process as defined in claim 2 wherein said ferrite is manganese-zinc ferrite.
Claim 7
Dependent Claim
28 words
A process as defined in claim 1, 2, 3 or 4 wherein said substrate has a positive electrical surface charge and said silica solution has a negative charge.
Claim 8
Dependent Claim
27 words
A process as defined in claim 1, 2, 3 or 4 further comprising the step of sputtering an alumina layer over said sealed surface of said substrate.
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) | 1988-04-22 | 1988-10-22 | 1989-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-22 | 1992-10-22 | 1993-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-22 | 1996-10-22 | 1997-04-23 | $7700.00 | Window Closed / Lapsed |