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US4020234A
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High-alumina content compositions containing BaO-MgO-SiO2 glass and sintered ceramic articles made therefrom
Assignee: International Business Machines Corp
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Filing: 1975-11-07
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Granted: 1977-04-26
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Expires: 1995-11-07
Abstract
Abstract The compositions of the present invention comprise alumina and minor proportions of a ternary glass sintering aid from the system: BaO-MgO-SiO 2 . The compositions can be sintered in a reducing atmosphere to provide ceramics which find particular utility in electrical devices, e.g., in multilayer ceramic sandwiches. The compositions are particularly amenable to formation by doctor blade slip casting techniques.
Inventors
- 👤 Richard A. Gardner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 01:27
CPC Classifications
H; H01; H01G; H01G4/00; H01G4/002; H01G4/018; H01G4/06; H01G4/08; H01G4/12; H01G4/129; C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; H01G4/1209; Y; Y10; Y10T; Y10T428/00; Y10T428/25; Y10T428/252; Y10T428/256; Y10T428/257; Y10T428/259
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
135 words
In a sintered multilayer ceramic sandwich comprising a plurality of ceramic layers separated by internal conductive metallization, the improvement wherein said ceramic layers consist essentially of a sintered alumina and material sinterable in a reducing atmosphere without blistering or mottling consisting essentially of alumina and a pre-fused ternary glass sintering aid from the system: BaO-MgO-SiO 2 said sintering alumina ceramic material having a dielectric constant of at most 9.5, which permits adequate speeds upon use in computer circuitry, and a dissipation factor less than 0.005, said ternary glass sintering aid being selected from compositions within the area bounded by A-B-C in the Figure, which points A-B-C represent the following compositions: ______________________________________
Point Mol % BaO Mol % MgO Mol % SiO.sub.2
______________________________________
A 15.0 15.0 70.0
B 43.5 17.5 39.0
C 17.5 43.5 39.0
______________________________________
Claim 2
Dependent Claim
135 words
In a sintered multilayer ceramic sandwich comprising a plurality of ceramic layers separated by internal conductive metallization, the improvement wherein said ceramic layers consist essentially of a sintered alumina and material sinterable in a reducing atmosphere without blistering or mottling consisting essentially of alumina and a pre-fused ternary glass sintering aid from the system: BaO-MgO-SiO 2 said sintering alumina ceramic material having a dielectric constant of at most 9.5, which permits adequate speeds upon use in computer circuitry, and a dissipation factor less than 0.005, said ternary glass sintering aid being selected from compositions within the area bounded by A-B-C in the Figure, which points A-B-C represent the following compositions: ______________________________________
Point Mol % BaO Mol % MgO Mol % SiO.sub.2
______________________________________
A 15.0 15.0 70.0
B 43.5 17.5 39.0
C 17.5 43.5 39.0
______________________________________
Claim 3
Dependent Claim
15 words
The sintered multilayer ceramic sandwich of claim 1 containing at least 80 wt. % alumina.
Claim 4
Dependent Claim
15 words
The sintered multilayer ceramic sandwich of claim 2 containing at least 90 wt. % alumina.
Claim 5
Dependent Claim
18 words
The sintered multilayer ceramic sandwich of claim 3 where the alumina is at least 99.5 wt. % alpha-alumina.
Claim 6
Dependent Claim
18 words
The sintered multilayer ceramic sandwich of claim 2 where the alumina is at least 95 wt. % alpha-alumina.
Claim 7
Dependent Claim
20 words
The sintered multilayer ceramic sandwich of claim 5 where the alumina has a particle size of 3 to 4 microns.
Claim 8
Dependent Claim
22 words
The sintered multilayer ceramic sandwich of claim 5 where the alumina has a surface area of less than 15 mg 2 /g.
Claim 9
Dependent Claim
22 words
The sintered multilayer ceramic sandwich of claim 1 where the alumina has a particle size of about 0.2 to about 10 microns.
Claim 10
Dependent Claim
23 words
The sintered multilayer ceramic sandwich of claim 1 where the alumina has a surface area of less than about 18 m 2 /g.
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) | 1980-04-25 | 1980-10-25 | 1981-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-25 | 1984-10-25 | 1985-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-25 | 1988-10-25 | 1989-04-26 | $7700.00 | Window Closed / Lapsed |