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1. WO2021061237 - MAGNETIC RECORDING APPARATUS COMPRISING DISK WITH REDUCED THICKNESS AND REDUCED DISK FLATNESS

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[ EN ]

WHAT IS CLAIMED IS:

1. A disk for a magnetic recording apparatus, comprising:

a substrate comprising a first surface and a second surface, wherein the substrate has a substrate thickness SI;

a first coating layer disposed over the first surface of the substrate, wherein the first coating layer has a first coating layer thickness Cl; and

a second coating layer disposed over the second surface of the substrate, wherein the second coating layer has a second coating layer thickness C2, wherein the disk has a disk thickness Dl,

wherein the disk thickness Dl includes the substrate thickness SI, and wherein a maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is a function of the square of the disk thickness Dl.

2. The disk of claim 1, wherein the disk thickness Dl includes the substrate thickness SI, the first coating layer thickness Cl and the second coating layer thickness C2.

3. The disk of claim 1, wherein the maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is a function of the square of a first ratio that includes the disk thickness Dl.

4. The disk of claim 3,

wherein a numerator of the first ratio includes the disk thickness Dl, and wherein a denominator of the first ratio is a thickness between 0.2 millimeter (mm) and 1 millimeter (mm).

5. The disk of claim 1,

wherein the substrate has a substrate Young’s modulus value El, and

wherein the maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is a function of (i) the square of a first ratio that includes the disk thickness Dl, and (ii) a second ratio that includes the substrate Young’s modulus value El.

6. The disk of claim 5,

wherein a numerator of the second ratio is the substrate Young’s modulus value El, and

wherein a denominator of the second ratio is in a range of about 60-80 gigapascals

(Gpa).

7. The disk of claim 5,

wherein the disk comprises a thickness of approximately 0.5 millimeter (mm) or less, wherein the disk comprises a flatness of approximately 20 micrometers (pm) or less, wherein the maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is 0.43 micrometer (pm), and

wherein the substrate Young’s modulus value El for the substrate is approximately 68 gigapascals (Gpa).

8. The disk of claim 5,

wherein the disk comprises a thickness of approximately 0.5 millimeter (mm) or less, wherein the disk comprises a flatness of approximately 20 micrometers (pm) or less, wherein the maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is 0.60 micrometer (pm), and

wherein the substrate Young’s modulus value El for the substrate is approximately 95 gigapascals (Gpa).

9. The disk of claim 1, wherein the maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is a function of

wherein Ei is a substrate Young’s modulus value for the substrate,

wherein Eo is a substrate Young’s modulus value for a particular substrate, wherein Di is a disk thickness for the disk,

wherein Do is a disk thickness for a particular disk comprising the particular substrate, and

wherein MTDo is a maximum thickness difference between a first particular coating layer thickness Clo and a second particular coating layer thickness C2o for the particular disk.

10. The disk of claim 9,

wherein the disk thickness D1 equals the substrate thickness SI, and

wherein Do is a disk thickness equals the substrate thickness of the particular substrate.

11. The disk of claim 1 ,

wherein the first coating layer thickness Cl has a thickness in a range of 12-30 micrometers (pm), and

wherein the second coating layer thickness C2 has a thickness in a range of 12-30 micrometers (pm).

12. The disk of claim 1, further comprising a magnetic recording layer disposed over the first coating layer, wherein the magnetic recording layer is configured to store information.

13. The disk of claim 1, wherein the first coating layer and the second coating layer comprises nickel phosphorous (NiP).

14. The disk of claim 13, wherein the substrate comprises glass.

15. The disk of claim 1, wherein the substrate comprises aluminum.

16. The disk of claim 15, wherein the substrate further comprises a material selected from the group consisting of magnesium, zinc, glass and combinations thereof.

17. A magnetic storage device configured to store information, comprising:

a disk comprising:

a substrate comprising a first surface and a second surface, wherein the substrate has a substrate thickness SI,

a first coating layer disposed over the first surface of the substrate, wherein the first coating layer has a first coating layer thickness Cl; and

a second coating layer disposed over the second surface of the substrate, wherein the second coating layer has a second coating layer thickness C2,

wherein the disk has a disk thickness Dl,

wherein the disk thickness Dl includes the substrate thickness SI, and wherein a maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is a function of the square of the disk thickness Dl, and

a slider configured to glide over a surface of the disk.

18. The magnetic storage device of claim 17, wherein the disk thickness Dl includes the substrate thickness SI, the first coating layer thickness Cl and the second coating layer thickness C2.

19. The magnetic storage device of claim 17, wherein the maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is a function of the square of a first ratio that includes the disk thickness Dl.

20. The magnetic storage device of claim 17, wherein the maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is a function


wherein Ei is a substrate Young’s modulus value for the substrate,

wherein Eo is a substrate Young’s modulus value for a particular substrate, wherein Di is a disk thickness for the disk,

wherein Do is a disk thickness for a particular disk comprising the particular substrate, and

wherein MTDo is a maximum thickness difference between a first particular coating layer thickness Clo and a second particular coating layer thickness C2o for the particular disk.

21. The magnetic storage device of claim 17,

wherein the disk thickness Dl equals the substrate thickness SI, and

wherein Do is a disk thickness equals the substrate thickness of the particular substrate.

22. A method for fabricating a disk for a magnetic recording apparatus, comprising: providing a substrate comprising a first surface and a second surface, wherein the substrate has a substrate thickness SI,

forming a first coating layer over the first surface of the substrate, wherein the first coating layer has a first coating layer thickness Cl; and

forming a second coating layer over the second surface of the substrate, wherein the second coating layer has a second coating layer thickness C2, wherein the disk is fabricated such that the disk has a disk thickness Dl, wherein the disk thickness Dl includes the substrate thickness SI, and wherein the second coating layer is formed over the second surface such that a maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is a function of the square of the disk thickness Dl.

23. The method of claim 22, wherein the disk thickness Dl includes the substrate thickness SI, the first coating layer thickness Cl and the second coating layer thickness C2.

24. The method of claim 22, wherein the maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is a function of the square of a first ratio that includes the disk thickness Dl.

25. The method of claim 24,

wherein a numerator of the first ratio includes the disk thickness Dl, and wherein a denominator of the first ratio is a thickness between 1 millimeter (mm) and 0.2 millimeter (mm).

26. The method of claim 22,

wherein the substrate has a substrate Young’s modulus value El, and

wherein the second coating layer is formed over the second surface such that the maximum thickness difference between the first coating layer thickness Cl and the second coating layer thickness C2 is a function of (i) the square of the first ratio that includes the disk thickness Dl, and (ii) a second ratio that includes the substrate Young’s modulus value El.

27. The method of claim 26,

wherein a numerator of the second ratio is the substrate Young’s modulus value El, and

wherein a denominator of the second ratio is in a range of about 60-80 gigapascals

(Gpa).

28. The method of claim 22, wherein the second coating layer is formed over the second surface such that the maximum thickness difference between the first coating layer thickness

Cl and the second coating layer thickness C2 is a function of MTD ,


wherein Ei is a substrate Young’s modulus value for the substrate,

wherein Eo is a substrate Young’s modulus value for a particular substrate, wherein Di is a disk thickness for the disk,

wherein Do is a disk thickness for a particular disk comprising the particular substrate, and

wherein MTDo is a maximum thickness difference between a first particular coating layer thickness Clo and a second particular coating layer thickness C2o for the particular disk.

29. The method of claim 28,

wherein the disk thickness Dl equals the substrate thickness SI, and

wherein Do is a disk thickness equals the substrate thickness of the particular substrate.

30. The method of claim 22, further comprising forming a magnetic recording layer over the first coating layer, wherein the magnetic recording layer is configured to store information.