US3725836A
Expired / Lapsed
US
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Thick film varistor and method for making the same
Assignee: Panasonic Holdings Corp
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Filing: 1971-05-25
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Granted: 1973-04-03
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Expires: 1991-05-25
Abstract
Abstract A thick film varistor having a thick film of finely divided particles of zinc oxide dispersed in a glass frit which bonds the particles together. Electrodes are provided on the thick film. The varistor is made by preparing a paste of the zinc oxide particles, the frit, and a liquid vehicle, and applying the paste to an insulating base. The paste is heated to evaporate the liquid vehicle and then melt the particles of frit to bond the particles of zinc oxide together. Thereafter the electrodes are applied. Alternatively, one electrode can be applied to the insulating base, the thick film formed thereon, and a second electrode applied to the surface of the thick film.
Inventors
- 👤 M Aoki
- 👤 Y Iida
- 👤 M Wada
- 👤 K Nishimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 06:30
CPC Classifications
H; H01; H01C; H01C17/00; H01C17/06; H01C17/065; H01C17/06506; H01C17/06513; H01C17/06533; H01C17/06546; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49082; Y10T29/49099
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
74 words
A thick film varistor consisting essentially of a thick film having 30 to 95 weight percent of finely divided particles of zinc oxide dispersed in 5 to 70 weight percent of glass frit and a pair of electrodes applied to said thick film, said finely divided particles of zinc oxide being obtained by heating zinc oxide powder at a temperature of 1100* to 1500*C and crushing the heated zinc oxide into finely divided particles.
Claim 2
Dependent Claim
36 words
A thick film varistor as claimed in claim 2, wherein said glass frit consists essentially of a glass selected from the group consisting of borosilicate glass, lead borosilicate glass, zinc leadborate glass and bismuth borosilicate glass.
Claim 3
Dependent Claim
42 words
A thick film varistor as claimed in claim 3, wherein said zinc leadborate glass consists essentially of 55 to 85 weight percent of lead oxide, 10 to 25 weight percent of boron oxide and 5 to 20 weight percent of zinc oxide.
Claim 4
Dependent Claim
22 words
A thick film varistor as claimed in claim 2, wherein at least one of said two electrodes is a silver paint electrode.
Claim 5
Dependent Claim
64 words
A thick film varistor as claimed in claim 5, wherein said silver paint electrode consists essentially of 50 to 95 weight percent of silver powder and 5 to 50 weight percent of glass frit, said glass frit consisting essentially of 60 to 80 weight percent of bismuth oxide, 10 to 20 weight percent of boron oxide and 10 to 20 weight percent of silica.
Claim 6
Independent Claim
104 words
A method for making a thick film varistor comprising providing a varistor paste comprising, as solid ingredients, 30 to 95 weight percent of finely divided particles of zinc oxide and 5 to 90 weight percent of finely divided particles of glass frit dispersed in a liquid vehicle; applying said varistor paste to an insulating base; heating the applied varistor paste to evaporate said liquid vehicle and to melt said finely divided particles of glass frit, whereby the melted glass frit bonds said finely divided particles of zinc oxide together and forms a thick film upon hardening; and providing said thick film with two electrodes.
Claim 7
Dependent Claim
31 words
A method for making a thick film varistor as claimed in claim 7, wherein said varistor paste is applied to an insulating base having one of said two electrodes formed thereon.
Claim 8
Dependent Claim
44 words
A method for making a thick film varistor as claimed in claim 7, wherein said finely divided particles of glass frit consist essentially of a member selected from the group consisting of borosilicate glass, lead borosilicate glass, zinc leadborate glass and bismuth borosilicate glass.
Claim 9
Dependent Claim
46 words
A method for making a thick film varistor as claimed in claim 9, wherein said zinc leadborate glass consists essentially of 55 to 85 weight percent of lead oxide, 10 to 25 weight percent of boron oxide and 5 to 20 weight percent of zinc oxide.
Claim 10
Dependent Claim
45 words
A method for making a thick film varistor as claimed in claim 7, wherein said finely divided particles of zinc oxide are made by heating zinc oxide powder at a temperature of 1100* to 1500*C and crushing the heated zinc oxide into finely divided particles.
Claim 11
Dependent Claim
42 words
A method for making a thick film varistor as claimed in claim 11, wherein said zinc oxide powder has incorporated therein 0.1 to 8 mole percent of a member selected from the group consisting of bismuth oxide, lead oxide and barium oxide.
Claim 12
Dependent Claim
26 words
A method for making a thick film varistor as claimed in claim 7, wherein at least one of said two electrodes is a silver paint electrode.
Claim 13
Dependent Claim
67 words
Amethod for making a thick film varistor as claimed in claim 13, wherein said silver paint electrode consists essentially of 50 to 95 weight percent of silver powder and 5 to 50 weight percent of glass frit, said glass frit consisting essentially of 60 to 80 weight percent of bismuth Oxide, 10 to 20 weight percent of boron oxide and 10 to 20 weight percent of silica.
References Cited (Backward Citations)
US3052573A
Cited
US3220881A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |