Plately alumina
AssigneeSt. Gobain/Norton Industrial Ceramics Corp.
InventorsTheresa R. Thibault, Edward L. Glavin, Jr.
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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.
Claims10
Platey alumina powder consisting essentially of individual euhedral platey alumina grains having diameters between 3 and 20 microns which has a D.sub.50 /D.sub.94 less than 1.45 and a D.sub.3 /D.sub.50 less than 1.6 and contains less than 5% of fragments of platey alumina particles.
Platey alumina powder with a D.sub.50 of 9 microns and no particles larger than 12 microns, having a bulk density of less than 1.35 g/cc.
Platey alumina powder consisting essentially of individual, euhedral, platey alumina particles having a D.sub.50 between 6 and 12 microns, a D.sub.3 /D.sub.50 of less than 1.6. a D.sub.50 /D.sub.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.
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.sub.50 of from about 6 to about 12;
- and
- d. separating and removing a fraction with particle sizes less than 3 microns.
Dependencies are inferred from the claim text.