Hard disk double lubrication layer
View Patent ↗Systems and methods are illustrated for manufacturing hard disks with double lubrication layers that allow minimization of a HDD head DFH touchdown point while maintaining good tribology performance for HDD reliability. An exemplary hard disk includes a magnetic recording layer, a carbon overcoat, and a double lubrication layer: a bonded lubrication layer and a mobile lubrication layer. The bonded lubrication layer includes a high conformity and high density first lubricant. The mobile layer include a high lubricity lubricant that promotes HDI reliability.
1. A hard disk lubrication layer, comprising:
a first lubrication layer bonded on a carbon overcoat of the hard disk, the first lubrication layer comprising a lubricant with chemical structure:
wherein Rc is a center connection structure with a connection number p, Re is a functional end group, and Rf is a fluorocarbon chain; and
a second lubrication layer on the first lubrication layer, wherein the second lubrication layer is a mobile layer comprising a lubricant with chemical structure:
Re—Rf—Re
wherein Re is a functional end group and Rf is a fluorinated chain;
wherein the first lubrication and the second lubrication layer comprise different lubricants;
wherein the center connection structure Rc is selected from the group consisting of (Rc1 through Rc14):
wherein the fluorocarbon chain Rf of the first lubrication layer is selected from the group consisting of (Rf3 through Rf6):
(R c )—CH 2 CF 2 O—(CF 2 CF 2 O) m —(CF 2 O) n —CF 2 CH 2 — ( m,n= 5˜25) R f3 :
(R c )—CH 2 CF 2 O—(CF 2 CF 2 O) p —CF 2 CH 2 — ( p= 10˜40) R f4 :
(R c )—CH 2 CF 2 O—(CF 2 CF 2 CF 2 O) q —CF 2 CH 2 — ( p= 5˜25) R f5 :
(R c )—CH 2 CF 2 O—(CF 2 CF 2 CF 2 CF 2 O) r —CF 2 CH 2 — ( r= 5˜25) R f6 :
wherein the functional end group Re of the lubricant of the first lubrication layer is selected from the group consisting of (Re1 through Re6):
wherein the functional end group Re of the lubricant of the second lubrication layer is selected from the group consisting of (Re1 through Re6):
2. The hard disk lubrication layer of claim 1 , wherein the first lubrication layer comprises per-fluoro-poly-ether (PFPE) lubricant.
3. The hard disk lubrication layer of claim 1 , wherein the thickness of the first lubrication layer is 5 Å to 10 Å.
4. The hard disk lubrication layer of claim 1 , wherein the thickness of the second lubrication layer is 2 Å to 4 Å.
5. A hard disk drive comprising:
a disk drive base;
a spindle motor attached to the disk drive base and configured to support a disk for rotating the disk with respect to the disk drive base surface; and
a rotatable disk, comprising:
a carbon overcoat on a magnetic recording layer;
a first lubrication layer bonded on a carbon overcoat of the hard disk, the first lubrication layer comprising a lubricant with chemical structure:
wherein Rc is a center connection structure with a connection number p, Re is a functional end group, and Rf is a fluorocarbon chain; and
a second lubrication layer on the first lubrication layer, wherein the second lubrication layer is a mobile layer comprising a lubricant with chemical structure:
Re—Rf—Re
wherein Re is a functional end group and Rf is a fluorinated chain; and
wherein the first lubrication and the second lubrication layer comprise different lubricants;
wherein the center connection structure Rc is selected from the group consisting of (Rc1 through Rc14):
wherein the fluorocarbon chain Rf of the first lubrication layer is selected from the group consisting of (Rf3 through Rf6):
(R c )—CH 2 CF 2 O—(CF 2 CF 2 O) m —(CF 2 O) n —CF 2 CH 2 — ( m,n= 5˜25) R f3 :
(R c )—CH 2 CF 2 O—(CF 2 CF 2 O) p —CF 2 CH 2 — ( p= 10˜40) R f4 :
(R c )—CH 2 CF 2 O—(CF 2 CF 2 CF 2 O) q —CF 2 CH 2 — ( p= 5˜25) R f5 :
(R c )—CH 2 CF 2 O—(CF 2 CF 2 CF 2 CF 2 O) r —CF 2 CH 2 — ( r= 5˜25) R f6 :
wherein the functional end group Re of the lubricant of the first lubrication layer is selected from the group consisting of (Re1 through Re6):
wherein the functional end group Re of the lubricant of the second lubrication layer is selected from the group consisting of (Re1 through Re6):
6. The hard disk drive of claim 5 , wherein the first lubrication layer comprises per-fluoro-poly-ether (PFPE) lubricant.
7. The hard disk drive of claim 5 , wherein the thickness of the first lubrication layer is 5 Å to 10 Å.
8. The hard drive of claim 5 , wherein the thickness of the second lubrication layer is 2 Å to 4 Å.
9. A method of lubricating a hard disk comprising a carbon overcoat, comprising:
creating a first lubrication layer on top of the carbon overcoat, the first lubrication layer comprising a lubricant with chemical structure:
wherein Rc is a center connection structure with a connection number p, Re is a functional end group, and Rf is a fluorocarbon chain; and
creating a second lubrication layer on top of the first lubrication layer wherein the second lubrication layer is a mobile layer comprising a lubricant with chemical structure:
Re—Rf—Re
wherein Re is a functional end group and Rf is a fluorinated chain; and
wherein the first lubrication and the second lubrication layer comprise different lubricants;
wherein the center connection structure Rc is selected from the group consisting of (Rc1 through Rc14):
wherein the fluorocarbon chain Rf of the first lubrication layer is selected from the group consisting of (Rf3 through Rf6):
(R c )—CH 2 CF 2 O—(CF 2 CF 2 O) m —(CF 2 O) n —CF 2 CH 2 — ( m,n= 5˜25) R f3 :
(R c )—CH 2 CF 2 O—(CF 2 CF 2 O) p —CF 2 CH 2 — ( p= 10˜40) R f4 :
(R c )—CH 2 CF 2 O—(CF 2 CF 2 CF 2 O) q —CF 2 CH 2 — ( p= 5˜25) R f5 :
(R c )—CH 2 CF 2 O—(CF 2 CF 2 CF 2 CF 2 O) r —CF 2 CH 2 — ( r= 5˜25) R f6 :
wherein the functional end group Re of the lubricant of the first lubrication layer is selected from the group consisting of (Re1 through Re6):
wherein the functional end group Re of the lubricant of the second lubrication layer is selected from the group consisting of (Re1 through Re6):
10. The method of claim 9 , wherein creating the first lubrication layer comprises:
coating the disk with a first solution comprising a first lubricant and a fluorosolvent; and
applying a bonding treatment to the disk to bond the first lubricant to the disk.
11. The method of claim 10 , wherein coating the disk with the first solution comprises:
dipping the disk into the first solution; and
removing the disk from the first solution at a first predetermined speed.
12. The method of claim 11 , wherein applying a bonding treatment comprises exposing the disk to UV light or heating the disk in a chamber.
13. The method of claim 11 , wherein creating the second lubrication layer comprises:
removing the non-bonding first lubricant from the disk using a strip solvent; and
coating the disk with a second solution comprising a second lubricant and a fluorosolvent.
14. The method of claim 13 , wherein coating the disk with the second solution comprises:
dipping the disk into the second solution; and
removing the disk from the second solution at a second predetermined speed.
15. The method of claim 14 , wherein the first and second predetermined speeds are between 1 mm/second and 2 mm/second.
16. The method of claim 9 , wherein the disk is a sputtered magnetic disk and the thickness of the carbon overcoat is between 10 Å and 30 Å.
17. The method of claim 9 , wherein creating the first lubrication layer comprises:
coating the disk with a vaporized first lubricant; and
applying a bonding treatment to the disk to bond the first lubricant to the disk; and wherein creating the second lubrication layer comprises:
removing the non-bonding first lubricant from the disk using a strip solvent; and
coating the disk with a vaporized second lubricant.