US4349496A
Expired / Lapsed
US
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Method for fabricating free-standing thick-film varistors
Assignee: General Electric Co
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Filing: 1981-03-26
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Granted: 1982-09-14
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Expires: 2001-03-26
Abstract
Abstract A free-standing, thick-film varistor is fabricated by screen printing on a smooth aluminum oxide substrate an unfired standard varistor powder mixed with a suitable organic carrier and heating the printed varistor at high temperature (1000° C.-1400° C.). The fabricated varistor adheres lightly to the insulating substrate and may be easily separated therefrom. The insulating substrate may be reused.
Inventors
- 👤 Lionel M. Levinson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:05
CPC Classifications
H; H01; H01C; H01C17/00; H01C17/06; H01C17/065; H01C17/06506; H01C17/06513; H01C17/06533; H01C17/06546
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
74 words
A method of fabricating a free-standing, thick-film varistor comprising the steps of: mixing unsintered metal oxide varistor powder with a carrier material to form a paste; applying a substantially uniform thin film of said paste onto a surface of an aluminum oxide substrate; sintering said thin paste film on said aluminum oxide substrate to form a varistor material; and separating said varistor material from said aluminum oxide substrate to form said free-standing, thick-film varistor.
Claim 2
Independent Claim
74 words
A method of fabricating a free-standing, thick-film varistor comprising the steps of: mixing unsintered metal oxide varistor powder with a carrier material to form a paste; applying a substantially uniform thin film of said paste onto a surface of an aluminum oxide substrate; sintering said thin paste film on said aluminum oxide substrate to form a varistor material; and separating said varistor material from said aluminum oxide substrate to form said free-standing, thick-film varistor.
Claim 3
Dependent Claim
54 words
The method of claim 1 wherein said varistor powder comprises ZnO as the primary constituent, Bi 2 O 3 , and at least one other material selected from the group consisting of Co 2 O 3 , MnO 2 , Sb 2 O 3 , BaCO 3 , and H 3 BO 3 .
Claim 4
Dependent Claim
50 words
The method of claim 1 or 2 wherein said step of sintering comprises the step of heating said thin paste film applied to said aluminum oxide substrate at a temperature of between about 1000° C. and about 1400° C. for a time of between about five minutes and five hours.
Claim 5
Dependent Claim
20 words
The method of claim 1 wherein said substrate comprises Al 2 O 3 having a purity of approximately 99 percent.
Claim 6
Dependent Claim
63 words
The method of claim 1 wherein said varistor powder comprises 0.5 mole percent of each of Bi 2 O 3 , Co 2 O 3 , MnO 2 , and SnO 2 , 1 mole percent of Sb 2 O 3 , 0.1 mole percent of BaCO 3 , 0.2 mole percent of H 3 BO 3 , and the remainder being ZnO.
Claim 7
Dependent Claim
55 words
The method of claim 1 or 2 wherein said varistor powder is mixed with sufficient quantities of a carrier material to form a material having a viscosity suitable for screen printing, and wherein said step of applying comprises the step of screen printing said unsintered varistor powder on a surface of said aluminum oxide substrate.
Claim 8
Dependent Claim
21 words
The method of claim 1 wherein at least one electrode is screen printed on said varistor subsequent to said sintering step.
Claim 9
Independent Claim
72 words
A method of fabricating a free-standing, thick film varistor, comprising the steps of: screen printing an unsintered metal oxide varistor powder on a smooth aluminum oxide substrate; sintering said screen printed varistor powder in air at a temperature of between approximately 1000° C. and 1400° C. for a time of between approximately five minutes and 5 hours to form a varistor material; and separating said varistor material from said aluminum oxide substrate.
Claim 10
Independent Claim
72 words
A method of fabricating a free-standing, thick film varistor, comprising the steps of: screen printing an unsintered metal oxide varistor powder on a smooth aluminum oxide substrate; sintering said screen printed varistor powder in air at a temperature of between approximately 1000° C. and 1400° C. for a time of between approximately five minutes and 5 hours to form a varistor material; and separating said varistor material from said aluminum oxide substrate.
Claim 11
Dependent Claim
54 words
The method of claim 8 wherein said varistor powder comprises ZnO as the primary constituent, Bi 2 O 3 , and at least one other material selected from the group consisting of Co 2 O 3 , MnO 2 , Sb 2 O 3 , BaCO 3 , and H 3 BO 3 .
Claim 12
Dependent Claim
20 words
The method of claim 8 wherein said substrate comprises Al 2 O 3 having a purity of approximately 99 percent.
Claim 13
Dependent Claim
63 words
The method of claim 8 wherein said varistor powder comprises 0.5 mole percent of each of Bi 2 O 3 , C 2 O 3 , MnO 2 , and SnO 2 , 1 mole percent of Sb 2 O 3 , 0.1 mole percent of BaCO 3 , 0.2 mole percent of H 3 BO 3 , and the remainder being ZnO.
Claim 14
Dependent Claim
29 words
The method of claim 8 wherein said varistor powder is mixed with sufficient quantities of a carrier material to form a material having a viscosity suitable for screen printing.
Claim 15
Dependent Claim
16 words
The method of claim 12 wherein said carrier material comprises ethyl cellulose dissolved in pine oil.
Claim 16
Dependent Claim
38 words
The method of claim 12 wherein said screen printed varistor is heated at a temperature between approximately 100° C. and 200° C. for a sufficient length of time to evaporate said carrier material prior to said sintering step.
Claim 17
Dependent Claim
21 words
The method of claim 8 wherein at least one electrode is screen printed on said varistor subsequent to said sintering step.
Claim 18
Dependent Claim
39 words
The method of claim 15 wherein said sintered varistor is heated at a temperature of between about 500° C. and 850° C. for a time of up to one hour to thereby bond said electrode to said sintered varistor.
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) | 1985-09-13 | 1986-03-15 | 1986-09-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-09-13 | 1990-03-15 | 1990-09-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-09-13 | 1994-03-15 | 1994-09-14 | $7700.00 | Window Closed / Lapsed |