US 12,437,781 B2
Glass sheet for fabricating magnetic recording media and method of fabricating magnetic recording media
Shoji Suzuki, San Jose, CA (US); and Mary Grace Shieh, San Jose, CA (US)
Assigned to Western Digital Technologies, Inc., San Jose, CA (US)
Filed by Western Digital Technologies, Inc., San Jose, CA (US)
Filed on Sep. 28, 2022, as Appl. No. 17/955,403.
Prior Publication US 2024/0101463 A1, Mar. 28, 2024
Int. Cl. G11B 5/73 (2006.01); C03B 33/04 (2006.01); G11B 5/84 (2006.01)
CPC G11B 5/73921 (2019.05) [G11B 5/8404 (2013.01); C03B 33/04 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A glass sheet configured to be cut into a plurality of glass substrates for magnetic recording disks, comprising:
a first surface,
wherein, for surface features of the first surface with a feature wavelength of 60 to 500 micrometers (μm), a root mean square of a surface topography of the surface features determined using a surface analysis on the first surface with incident and reflected light is given as a microwaviness, and
wherein a maximum value of the microwaviness of any arbitrary region of the first surface is between 1.2 nanometers (nm) and 2.8 nm, inclusive of 1.2 nm and 2.8 nm, and
wherein the microwaviness is based on the root mean square of the surface topography of the surface features determined using displacement data generated by the surface analysis on the first surface with a filter applied for a frequency range corresponding to the feature wavelength of 60 to 500 μm.