Chemical strengthening process for disks used in disk drive data storage devices
AssigneeInternational Business Machines Corporation
InventorsNathan Ellis Jacobson, Terry Lee Jensen, Rick Allan Sprague
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Abstract
A salt mixture used for chemical strengthening of data recording disks is subjected to sub-micron filtration prior to use to remove certain impurities. Preferably, glass disks are chemically strengthened by ion exchange in a bath of molten sodium nitrate and potassium nitrate. A salt fresh mixture is prepared by starting with high-grade bulk salt in the intended proportions, melting the salt, and filtering the salt in a stainless steel filter, which is preferably approximately 2 micron or smaller. Filtration removes trace amounts of certain contaminants. The salt mixture thus prepared is then used for chemical strengthening of disks in the conventional manner.
Claims20
A method for manufacturing a disk substrate for a rotating disk drive data storage device, comprising the steps of:
- forming a disk substrate of a chemically strengthenable material to a desired shape and surface finish;
- filtering a molten salt composition with a filter having a filter media size of 10 microns or less to remove impurities from said molten salt composition, thereby producing a filtered molten salt composition;
- and
- chemically strengthening said disk substrate by immersion in said filtered molten salt composition.
A method for chemically strengthening a disk substrate for a rotating disk drive data storage device, comprising the steps of:
- filtering a molten salt composition with a filter having a filter media size of 10 microns or less to remove impurities from said molten salt composition, thereby producing a filtered molten salt composition;
- and
- chemically strengthening a disk substrate formed of a chemically strengthenable material by immersion in said filtered molten salt composition.
Dependencies are inferred from the claim text.