US5234641A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making varistor or capacitor
Assignee: Kyocera Avx Components Corp
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Filing: 1988-05-06
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Granted: 1993-08-10
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Expires: 2008-05-06
Abstract
Abstract A method of manufacturing an improved visitor or capacitor, and the resultant improved varistor or capacitor is described. In accordance with the method the ceramic layers of the varistor are formed by providing at least two strata separated by a boundary layer which resists grain growth thereacross. The ceramic body is sintered under temperature conditions sufficiently low that grain growth within the strata defining the ceramic layers is restricted to the strata such that grain growth across the boundary material is minimized. By this method the ceramic layers have a predictable number of grain boundaries between adjacent electrodes.
Inventors
- 👤 Truman Rutt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:08
CPC Classifications
H; H01; H01G; H01G9/00; H01C; H01C7/00; H01C7/10; H01C7/102; H01C7/12; H01G4/00; H01G4/002; H01G4/018; H01G4/06; H01G4/08; H01G4/12
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
148 words
In the method of forming a monolithic ceramic varistor or capacitor of the type comprising alternate layers of ceramic material having electrodes interposed there between, adjacent said electrodes being electrically isolated from each other and alternate said electrodes being connected to each other, the improvement which comprises forming a green ceramic preform of a plurality of stacked layers of green ceramic, said layers comprising a plurality of discreet strata said strata including ceramic particles in an organic binder, the ratio of binder to ceramic in said strata being greater at the surfaces of said strata than at the interior of said strata, thereafter heating said preform to drive off said binder, and thereafter sintering said preform at sintering temperatures sufficiently high to fuse said ceramic particles into grains, said temperatures being sufficiently low as to resist the formation of grains merging across the boundaries between adjacent said strata.
Claim 2
Dependent Claim
148 words
In the method of forming a monolithic ceramic varistor or capacitor of the type comprising alternate layers of ceramic material having electrodes interposed there between, adjacent said electrodes being electrically isolated from each other and alternate said electrodes being connected to each other, the improvement which comprises forming a green ceramic preform of a plurality of stacked layers of green ceramic, said layers comprising a plurality of discreet strata said strata including ceramic particles in an organic binder, the ratio of binder to ceramic in said strata being greater at the surfaces of said strata than at the interior of said strata, thereafter heating said preform to drive off said binder, and thereafter sintering said preform at sintering temperatures sufficiently high to fuse said ceramic particles into grains, said temperatures being sufficiently low as to resist the formation of grains merging across the boundaries between adjacent said strata.
Claim 3
Dependent Claim
44 words
The method in accordance with claim 1 wherein said layers are formed by first forming planar sheets of said green ceramic comprised of ceramic particles and binder, each said sheet defining a stratum, and stacking a plurality of said sheets to form said layer.
Claim 4
Dependent Claim
46 words
The method in accordance with claim 1 wherein said layers are formed by forming a first sheet of said ceramic particles and binder to define a stratum, and depositing on said first sheet a liquid mass of ceramic particles and binder to define a second stratum.
Claim 5
Dependent Claim
24 words
The method in accordance with claim 3 and including the step of leveling said liquid mass which has been deposited on said first sheet.
Claim 6
Dependent Claim
27 words
The method in accordance with claim 4 wherein said depositing step is carried out by spraying said mixture of ceramic particles and binder on said first sheet.
Claim 7
Dependent Claim
25 words
The method in accordance with claim 4 wherein said leveling step is performed by passing said sheet carrying said liquid mass beneath a leveling mechanism.
Claim 8
Dependent Claim
16 words
The method in accordance with claim 6 wherein said leveling step is performed by a doctor-blade.
Claim 9
Dependent Claim
24 words
The method in accordance with claim 4 wherein said leveling step is performed by passing said sheet and liquid mass beneath a leveling roller.
Claim 10
Dependent Claim
52 words
The method in accordance with claim 1 wherein said layers are formed by extruding a liquid mass of said ceramic particles and binder to form a sheet, causing said binder to at least partly solidify to define a first said stratum, and thereafter forming a second said stratum atop said first stratum.
Claim 11
Dependent Claim
85 words
The method in accordance with claim 1 and including the step of partially separating the layers of said preform by areas of organic material in the areas to be occupied by said electrodes said areas of organic material extending to margins of said preform, causing said organic material to be driven off by said heating and sintering steps to define voids between said layers in the areas previously occupied by said organic material, and thereafter introducing conductive material into said voids to form said electrodes.
Claim 12
Dependent Claim
44 words
The method in accordance with claim 1 and including the step of partially separating the layers of said preform by areas of conductive materials in the areas to be occupied by said electrodes, said areas of conductive material extending to margins of said preform.
Claim 13
Independent Claim
75 words
The method of manufacturing a varistor or capacitor including a dielectric layer of layers having electrodes covering at least major portions of the opposite surfaces of said layer or layers which comprises forming said layer or layers of a plurality of green ceramic strata, adjacent said strata having a grain growth barrier interposed therebetween, and sintering said layer or layers under heating temperatures sufficiently low as to minimize the growth of grains across said barriers.
Claim 14
Independent Claim
75 words
The method of manufacturing a varistor or capacitor including a dielectric layer of layers having electrodes covering at least major portions of the opposite surfaces of said layer or layers which comprises forming said layer or layers of a plurality of green ceramic strata, adjacent said strata having a grain growth barrier interposed therebetween, and sintering said layer or layers under heating temperatures sufficiently low as to minimize the growth of grains across said barriers.
Claim 15
Dependent Claim
42 words
The method in accordance with claim 12 and including the step of forming said layer by first forming strata comprised of ceramic particles suspended in an organic binder material and stacking a plurality of increments of said strata under heat and pressure.
Claim 16
Dependent Claim
24 words
The method in accordance with claim 13 wherein said strata include higher binder concentrations at the major surfaces thereof then in the interior thereof.
Claim 17
Dependent Claim
48 words
The method in accordance with claim 12 wherein said layer is formed by first providing a stratum comprised by ceramic particle suspended in a binder, and thereafter spreading atop said first stratum a layer of ceramic particles suspended in a liquid comprised of organic binder materials and solvent.
Claim 18
Independent Claim
132 words
The method of forming a varistor or capacitor device comprised of at least one ceramic layer, the major portion of the opposed surfaces of said layer being covered by electrodes, the grain size distribution between the upper and lower surfaces throughout said layer being maintained within a predetermined range which is less than the distance between said upper and lower surfaces comprising forming a green ceramic preform comprised of a plurality of distinct green strata, said strata including ceramic particles, the surface of adjacent portions of said strata including barriers inhibiting grain growth there across, thereafter sintering said preform to form said layer, said sintering being carried out at a temperature sufficiently high to fuse said ceramic particles but sufficiently low to resist the formation of ceramic particles extending across said barriers.
Claim 19
Independent Claim
132 words
The method of forming a varistor or capacitor device comprised of at least one ceramic layer, the major portion of the opposed surfaces of said layer being covered by electrodes, the grain size distribution between the upper and lower surfaces throughout said layer being maintained within a predetermined range which is less than the distance between said upper and lower surfaces comprising forming a green ceramic preform comprised of a plurality of distinct green strata, said strata including ceramic particles, the surface of adjacent portions of said strata including barriers inhibiting grain growth there across, thereafter sintering said preform to form said layer, said sintering being carried out at a temperature sufficiently high to fuse said ceramic particles but sufficiently low to resist the formation of ceramic particles extending across said barriers.
Claim 20
Dependent Claim
18 words
The method of claim 16 wherein said barriers comprise areas of mixed ceramic particles and heat fugitive binders.
Claim 21
Dependent Claim
12 words
The method of claim 17 wherein said binder is an organic material.
Claim 22
Dependent Claim
28 words
The method of claim 18 wherein the surface adjacent areas of said strata include a higher binder to ceramic concentration than the areas intermediate said surface adjacent areas.
Claim 23
Dependent Claim
12 words
The method of claim 16, wherein said barriers comprise a surface coating.
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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) | 1996-08-09 | 1997-02-08 | 1997-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-09 | 2001-02-08 | 2001-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-09 | 2005-02-08 | 2005-08-10 | $7700.00 | Window Closed / Lapsed |