Magnetic disk drive having a surface coating on a magnetic disk
View Patent ↗A magnetic disk is produced with improved yield by forming a DLC protective film by a d.c. magnetron sputtering process conducted in a sputtering atmosphere containing oxygen. The magnetic disk carries a lubricating film on the DLC film wherein a fluorocarbon resin constituting the lubricating film contains photocrosslinking groups. A lubricating film having non-polar end groups is also disclosed.
1. A method of making a magnetic disk, comprising the steps of:
coating a disk surface with a lubricating layer comprising molecules having a photocrosslinking functional group;
causing a crosslinking in said molecules by applying an optical radiation to said lubricating layer,
wherein said step of causing said crosslinking is conducted by applying a substantially monochromatic far-ultraviolet radiation with a wavelength corresponding to an absorption wavelength of said photocrosslinking functional group as said optical radiation such that a bonding ratio is 85.5% or more in said coated lubricating layer,
wherein said lubricating layer is excited optically in an ambient containing oxygen with a concentration of 10 ppm or less,
wherein said far-ultraviolet radiation has a half-height width of 15 nm or less by a Xe 2 excimer radiation having a wavelength of 172 nm,
wherein a source of said far-ultraviolet radiation is disposed with a separation distance of about 5 nm from said disk surface.
2. A method as claimed in claim 1 , wherein said photocrosslinking functional group is selected from the group consisting of: an alkenyl group, an alkenyl halide group, an aryl halide group, an aryl azide group, piperonyl group and epoxy group.
3. A method as claimed in claim 1 , wherein said step of causing said crosslinking is conducted while applying heat to said lubricating layer.
4. A method as claimed in claim 1 , wherein said lubricating layer is formed of a resin having a molecular weight of 1200 or more in terms of the molecular weight of polystyrene.
5. The method as claimed in claim 1 , wherein exposure of said lubricating layer to said far-ultraviolet radiation is conducted such that a contact angle of 116 degrees or more is achieved for water on said lubricating layer.
6. The method as claimed in claim 1 , wherein said lubricating layer has a thickness of 2.5 nm or less.
7. The method as claimed in claim 1 , wherein said photocrosslinking functional group comprises a CF 3 group.
8. A method of making a magnetic disk, comprising the steps of:
coating a disk surface with a lubricating layer comprising molecules having a photocrosslinking functional group; and
causing a crosslinking in said molecules by applying an optical radiation to said lubricating layer;
wherein said step of causing said crosslinking is conducted by applying a substantially monochromatic far-ultraviolet radiation with a wavelength corresponding to an absorption wavelength of said photocrosslinking functional group as said optical radiation such that a bonding ratio is 85.5% or more in said coated lubricating layer;
wherein there is provided a carbon film having a thickness of 8 nm or less as an underlayer of said lubricating layer provided underneath said lubricating layer,
wherein said lubricating layer is excited optically in an ambient containing oxygen with a concentration of 10 ppm or less,
wherein said far-ultraviolet radiation has a half-height width of 15 nm or less by a Xe 2 excimer radiation having a wavelength of 172 nm,
wherein a source of said far-ultraviolet radiation is disposed with a separation distance of about 5 nm from said disk surface.
9. A method as claimed in claim 8 , wherein said photocrosslinking functional group is selected from the group consisting of: an alkenyl group, an alkenyl halide group, an aryl halide group, an aryle azide group, piperonyl group, and epoxy group.
10. A method as claimed in claim 8 , wherein said step of causing said crosslinking is conducted while applying heat to said lubricating layer.
11. A method as claimed in claim 8 , wherein said lubricating layer is formed of a resin having a molecular weight of 1200 or more in terms of the molecular weight of polystyrene.
12. The method as claimed in claim 8 , wherein said lubricating layer has a thickness of 2.5 nm or less.
13. The method as claimed in claim 8 , wherein said photocrosslinking functional groupcomprises a CF 3 group.
14. A method of making a magnetic disk, comprising the steps of:
coating a disk surface with a lubricating layer comprising molecules having a photocrosslinking functional group;
causing a crosslinking in said molecules by applying an optical radiation to said lubricating layer; and
dipping said lubricating layer in a solvent;
wherein said step of causing said crosslinking is conducted by applying a substantially monochromatic far-ultraviolet radiation with a wavelength corresponding to an absorption wavelength of said photocrosslinking functional group as said optical radiation such that a bonding ratio is 85.5% or more in said coated lubricating layer,
wherein there is provided a carbon film having a thickness of 8 nm or less as an underlayer of said lubricating layer provided underneath said lubricating layer,
wherein said lubricating layer is excited optically in an ambient containing oxygen with a concentration of 10 ppm or less,
wherein said far-ultraviolet radiation has a half-height width of 15 nm or less by a Xe 2 excimer radiation having a wavelength of 172 nm,
wherein a source of said far-ultraviolet radiation is disposed with a separation distance of about 5 nm from said disk surface.
15. A method as claimed in claim 14 , wherein said photocrosslinking functional group is selected from the group consisting of: an alkenyl group, an alkenyl halide group, an aryl halide group, an aryl azide group, piperonyl group and epoxy group.
16. A method as claimed in claim 14 , wherein said step of causing said crosslinking is conducted while applying heat to said lubricating layer.
17. A method as claimed in claim 14 , wherein said lubricating layer is formed of a resin having a molecular weight of 1200 or more in terms of the molecular weight of polystyrene.
18. The method as claimed in claim 14 , wherein said lubricating layer has a thickness of 2.5 nm or less.
19. The method as claimed in claim 14 , wherein said photocrosslinking functional group comprises a CF 3 group.