Patent US5277702A successfully refreshed from Google Patents.
US5277702A
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Plately alumina
Assignee: Saint Gobain Ceramics and Plastics Inc
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Filing: 1993-03-08
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Granted: 1994-01-11
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Expires: 2013-03-08
Abstract
Abstract A novel platey alumina with essentially no aggregates, fines or fragments has been obtained. This product proves very advantageous in lapping substrate wafers for microelectronic applications. A process for making such products is also described.
Inventors
- 👤 Theresa R. Thibault
- 👤 Edward L. Glavin, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 10:04
CPC Classifications
C; C01; C01F; C01F7/00; C01F7/02; C09; C09K; C09K3/00; C09K3/14; C09K3/1409; C09K3/1418; C01F7/021; C01F7/022; C01F7/023; C09C; C09C1/00; C09C1/62; C09C1/64; C01P; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/20; C01P2004/51; C01P2004/60; C01P2004/61; C01P2006/00; C01P2006/10
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
48 words
Platey alumina powder consisting essentially of individual euhedral platey alumina grains having diameters between 3 and 20 microns which has a D 50 /D 94 less than 1.45 and a D 3 /D 50 less than 1.6 and contains less than 5% of fragments of platey alumina particles.
Claim 2
Dependent Claim
48 words
Platey alumina powder consisting essentially of individual euhedral platey alumina grains having diameters between 3 and 20 microns which has a D 50 /D 94 less than 1.45 and a D 3 /D 50 less than 1.6 and contains less than 5% of fragments of platey alumina particles.
Claim 3
Dependent Claim
19 words
Platey alumina powder according to claim 1 in which the D 50 /D 94 ratio is less than 1.4.
Claim 4
Dependent Claim
22 words
Platey alumina powder according to claim 1 in which at least 90% of the particles have sizes between 6 and 12 microns.
Claim 5
Dependent Claim
26 words
Platey alumina powder with a D 50 of 9 microns and no particles larger than 12 microns, having a bulk density of less than 1.35 g/cc.
Claim 6
Dependent Claim
26 words
Platey alumina powder with a D 50 of 9 microns and no particles larger than 12 microns, having a bulk density of less than 1.35 g/cc.
Claim 7
Dependent Claim
59 words
Platey alumina powder consisting essentially of individual, euhedral, platey alumina particles having a D 50 between 6 and 12 microns, a D 3 /D 50 of less than 1.6. a D 50 /D 94 of less than 1.4, which is essentially free of fines and aggregates and which contains less than 5% of fragments of such platey alumina particles.
Claim 8
Dependent Claim
59 words
Platey alumina powder consisting essentially of individual, euhedral, platey alumina particles having a D 50 between 6 and 12 microns, a D 3 /D 50 of less than 1.6. a D 50 /D 94 of less than 1.4, which is essentially free of fines and aggregates and which contains less than 5% of fragments of such platey alumina particles.
Claim 9
Dependent Claim
89 words
A process for the production of a platey alumina lapping powder which comprises: a. providing a platey alumina product containing from about 10 to about 30% by weight of aggregates; b. classifying the platey alumina product into a coarse fraction and a fine fraction containing particles smaller than 6 microns; c. wet milling the coarse fraction until the particle size of the powder has reached a D 50 of from about 6 to about 12; and d. separating and removing a fraction with particle sizes less than 3 microns.
Claim 10
Dependent Claim
89 words
A process for the production of a platey alumina lapping powder which comprises: a. providing a platey alumina product containing from about 10 to about 30% by weight of aggregates; b. classifying the platey alumina product into a coarse fraction and a fine fraction containing particles smaller than 6 microns; c. wet milling the coarse fraction until the particle size of the powder has reached a D 50 of from about 6 to about 12; and d. separating and removing a fraction with particle sizes less than 3 microns.
Claim 11
Dependent Claim
32 words
A process according to claim 6 in which the aggregate-containing platey alumina is obtained by lightly dry milling an as-produced, calcined, platey alumina product till the percentage of aggregates has been reduced.
Claim 12
Dependent Claim
19 words
A process according to claim 6 in which, after the wet-milling operation, particles smaller than 6 microns are removed.
Claim 13
Dependent Claim
59 words
A process according to claim 6 in which, after the wet-milling, at least part of the fines are separated in an operation in which the slurry of alumina in water discharged from the wet milling operation is allowed to settle to form a water layer and a slurry layer, and a fines component is removed with the water layer.
Claim 14
Dependent Claim
37 words
A process according to claim 9 in which the fines separation after the wet-milling also includes air-classification after the milled slurry has been separated, dried and lightly milled to break up any loose aggregates formed during drying.
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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) | 1997-01-10 | 1997-07-12 | 1998-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-01-10 | 2001-07-12 | 2002-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-01-10 | 2005-07-12 | 2006-01-11 | $7700.00 | Window Closed / Lapsed |