Method of surface-finishing glass substrate for magnetic disks and glass substrate for magnetic disks
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United States of America Patent
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Feb 7, 2012
Grant Date -
Oct 21, 2010
app pub date -
Mar 24, 2008
filing date -
May 30, 2007
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Abstract
An inner peripheral edge of a toroidal glass substrate for a magnetic disk is subjected to mechanical polishing in such a manner that the surface roughness is no greater than 9 nm in terms of Rmax. Then, the inner peripheral edge is subjected to chemical polishing to remove at least 2 μm of a surface layer. The inner peripheral edge has a non-conventional mirror-finished surface obtained by mechanical polishing. Thus, sufficient ring strength is obtained even when the chemical polishing depth is smaller than in the past. A polishing depth of less than 5 μm is sufficient.
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