Patent US3854965A successfully refreshed from Google Patents.
US3854965A
Expired / Lapsed
US
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Method of manufacture of alumina substrate with improved smoothness and electrical properties
Assignee: Fujitsu Ltd
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Filing: 1973-02-22
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Granted: 1974-12-17
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Expires: 1993-02-22
Abstract
Abstract An alumina substrate with improved surface smoothness and electrical properties is provided by the addition of small quantities of magnesium oxide and chromium oxide to alumina powder, slip casting and firing at a temperature of 1550 to 1670*C.
Inventors
- 👤 K Niwa
- 👤 Y Anzai
- 👤 K Hashimoto
- 👤 H Yokoyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:42
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; H; H05; H05K; H05K1/00; H05K1/02; H05K1/03; H05K1/0306
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
77 words
A METHOD OF MANUFACTURE OF AN ALUMINA SUBSTRATE WITH IMPROVED SURFACE SMOOTHNESS AND ELECTRICAL PROPERTIES, COM PRISING THE STEPS OF MAKING A MIXTURE POWDER CONTAINING MAGNESIUM OXIDE OF 0.1 TO 0.4 WT. %, CHROMIUM OXIDE OF 0.0001 TO 0.05 WT. % AND A REMAINDER OF ALUMINA POWDER, PRODUCING A SLIP FROM THE MIXTURE POWDER; FORMING A GREEN SHEET BY CASTING THE SLIP; AND FIRING THE GREEN SHEET AT A TEMPERATURE IN THE RANGE OF 1550 TO 1670*C.
Claim 2
Independent Claim
77 words
A METHOD OF MANUFACTURE OF AN ALUMINA SUBSTRATE WITH IMPROVED SURFACE SMOOTHNESS AND ELECTRICAL PROPERTIES, COM PRISING THE STEPS OF MAKING A MIXTURE POWDER CONTAINING MAGNESIUM OXIDE OF 0.1 TO 0.4 WT. %, CHROMIUM OXIDE OF 0.0001 TO 0.05 WT. % AND A REMAINDER OF ALUMINA POWDER, PRODUCING A SLIP FROM THE MIXTURE POWDER; FORMING A GREEN SHEET BY CASTING THE SLIP; AND FIRING THE GREEN SHEET AT A TEMPERATURE IN THE RANGE OF 1550 TO 1670*C.
Claim 3
Dependent Claim
21 words
A method of manufacture of an alumina substrate as claimed in claim 1, wherein the green sheet is fired in hydrogen.
Claim 4
Dependent Claim
50 words
A method of manufacture of an alumina substrate as claimed in claim 1, wherein the slip is produced from the alumina powder by the addition of a deflocculent, a solvent of methyl ethyl ketone, methyl alcohol and n-butyl alcohol, a plasticizer of dibutyl phthalate, and a binder of polyvinyl butyral.
Claim 5
Dependent Claim
33 words
A method of manufacture of an alumina substrate as claimed in claim 1, wherein the alumina powder consists of gamma -alumina powder of 30 wt % or less and residual Alpha -alumina powder.
Claim 6
Dependent Claim
46 words
A metHod of manufacture of an alumina substrate as claimed in claim 1, wherein magnesium oxide of 0.25 wt. % and chromium oxide of 0.02 to 0.03 wt % are added to the alumina powder and the green sheet is fired at a temperature of 1600*C.
Claim 7
Dependent Claim
94 words
A method of manufacture of an alumina substrate as claimed in claim 1, wherein the slip is produced by adding to 100 parts by weight of alumina powder, 0.8 to 1.5 parts by weight of a deflocculent, a solvent of 20 to 30 parts by weight of methyl ethyl ketone, 10 to 20 parts by weight of methyl alcohol and 8 to 12 parts by weight of n-butyl alcohol, a plasticizer of 0.5 to 1.2 parts by weight of dibutyl phthalate and a binder of 5.5 to 9.5 parts by weight of polyvinyl butyral.
Claim 8
Dependent Claim
23 words
A method of manufacture of an alumina substrate as claimed in claim 4, wherein gamma -alumina powder of 10 wt % is added.
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) | 1977-12-16 | 1978-06-17 | 1978-12-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-16 | 1982-06-17 | 1982-12-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-16 | 1986-06-17 | 1986-12-17 | $7700.00 | Window Closed / Lapsed |