WO2006022443A1 - Magnetic disk substrate and production method of magnetic disk - Google Patents

Magnetic disk substrate and production method of magnetic disk Download PDF

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Publication number
WO2006022443A1
WO2006022443A1 PCT/JP2005/016049 JP2005016049W WO2006022443A1 WO 2006022443 A1 WO2006022443 A1 WO 2006022443A1 JP 2005016049 W JP2005016049 W JP 2005016049W WO 2006022443 A1 WO2006022443 A1 WO 2006022443A1
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WO
WIPO (PCT)
Prior art keywords
magnetic disk
production method
glass substrate
substrate
value
Prior art date
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Ceased
Application number
PCT/JP2005/016049
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French (fr)
Inventor
Hiroyuki Machida
Katsuaki Aida
Kazuyuki Haneda
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Resonac Holdings Corp
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Showa Denko KK
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Filing date
Publication date
Application filed by Showa Denko KK filed Critical Showa Denko KK
Priority to US11/660,684 priority Critical patent/US20070243421A1/en
Publication of WO2006022443A1 publication Critical patent/WO2006022443A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
    • B24B37/042—Lapping machines or devices; Accessories designed for working plane surfaces operating processes therefor
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C19/00—Surface treatment of glass, not in the form of fibres or filaments, by mechanical means
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
    • G11B5/8404—Processes or apparatus specially adapted for manufacturing record carriers manufacturing base layers

Definitions

  • This invention relates to a magnetic disk substrate and a production method of a magnetic disk.
  • Magnetic disk devices have made remarkable progress, as external storage devices of computers, owing to their superior cost/performance ratio and further growth is expected.
  • a magnetic head flies a predetermined height above a substrate surface when the magnetic disk rotates. This height has become smaller, with the recent requirement for a higher recording density, and the magnetic force of the magnetic head operates on only a small area of a magnetic thin film layer on the substrate and this makes it possible to achieve a higher density.
  • the danger of mis-operations of the devices, due to contact between the magnetic head and the substrate surface has become higher.
  • the flatness of the surface of the magnetic disk is important.
  • An aluminum type substrate has been used in the past as a substrate of a magnetic disk which is mounted in the magnetic disk device, but glass substrates, made of chemically tempered glass and crystallized glass, have gradually gained a wider application because they have high impact resistance and can more easily be made flat.
  • the aluminum type substrate can easily provide a magnetic disk having excellent magnetic characteristics but involves the problem of flatness because it suffers plastic deformation during a mechanical process such as polishing.
  • the glass substrate can be easily made flat because it has high surface hardness and does not involve the plastic deformation described above.
  • Japanese Unexamined Patent Publication (Kokai) No. 2002- 92867) Another method sets the surface roughness of the glass substrate and its microwaviness to a predetermined range/relation (Japanese Unexamined Patent Publication (Kokai) No. 2002-163818) . Further, a glass substrate in which microwaviness of the surface has a cycle of 0.1 to 5 mm and amplitude of 0.1 to 1 nm has been proposed (Japanese Unexamined Patent Publication (Kokai) No. 2000- 207737) .
  • the invention provides a method capable of efficiently polishing a glass substrate so that its degree of flatness (TIR value) becomes 5 ⁇ m or below.
  • the invention provides the following inventions.
  • a production method of a magnetic disk substrate by polishing a glass substrate by lapping by using a lap plate characterized in that plate accuracy is set to 180 ⁇ m or below and polishing is carried out until a degree of flatness (TIR value) of the glass substrate becomes 5 ⁇ m or below.
  • the present invention provides a method capable of efficiently conducting polishing so that a degree of flatness (TIR value) of a glass substrate is 5 ⁇ m or below.
  • lapping accuracy is set to 180 ⁇ m or below and polishing is carried out until the degree of flatness (TIR value) of the glass substrate becomes 5 ⁇ m or below when the glass substrate is polished by lapping by using a lap plate.
  • Amorphous, chemically tempered or crystallized glass that has generally been used for the magnetic disk substrate, can be used as the glass substrate in the invention.
  • glasses such as soda lime, aluminosilicate, lithium silicate, lithium aluminosilicate, aluminoborosilicate glasses, and so forth.
  • the chemically tempered glass glass that is brought into contact with a molten salt at a high temperature to cause ion exchange of alkali ions in the glass with different kinds of alkali ions in the molten salt and is tempered by the compressive stress is suitable.
  • the crystallized glass are those which are obtained by re-heating glass under a controlled condition and precipitating and growing a large number of fine crystals .
  • Such glass substrates are generally selected from the range of about 0 . 1 to about 2 mm.
  • polishing of the glass substrate is carried out by lapping using a lap plate until the degree of flatness (TIR value) is 5 ⁇ m or below, preferably 4 ⁇ m or below and further preferably 3 ⁇ m or below.
  • Lapping is defined as a pre-process to polishing.
  • lapping is carried out by abrading the glass substrate surface and the plate through free abrasives dispersed in water, etc.
  • fixed abrasives such as diamond pellets or a diamond plate are used.
  • the abrasives are aluminum oxide, zirconium oxide, silicon carbide and so forth, but aluminum oxide is suitable from the aspect of a polishing speed, etc.
  • lapping itself is carried out in a customary manner but it is necessary to set plate accuracy to 180 ⁇ m or below. Adjustment of plate accuracy itself can be done in a customary manner.
  • plate accuracy is selected to preferably 150 ⁇ m or below, further preferably to 80 ⁇ m or below and most preferably 50 ⁇ m or below.
  • the degree of flatness (TIR value) of the resulting glass substrate can be easily set to 5 ⁇ m or below by setting plate accuracy to 180 ⁇ m or below.
  • This degree of flatness (TIR value: Total Indicated Run ⁇ out) represents the measurement result of top/valley indicating the difference between the highest point and the lowest point on the substrate surface with respect to a plane that is most optimally fit.
  • an end face of the glass substrate on the inner circumferential side facing an inner diameter hole and an end face on the outer circumferential side are respectively chamfered to give chamfer portions.
  • the end faces of the glass substrate on both inner and outer circumferential sides processed in this way are subjected to polishing into mirror surfaces.
  • the main surface of the glass substrate is finally polished to a mirror surface.
  • the glass substrate is washed and dried in a customary manner and a magnetic disk glass substrate can be acquired.
  • the microwaviness value of the glass substrate can be easily reduced to 0.5 nm or below, preferably 0.3 nm or below.
  • This microwaviness value means that having a corrugation substrate surface, a cycle in the order of mm and amplitude in the order of nm. It is measured by using an "OPTIFLAT" (product of ADE Phase Shift Co.) (filter 5mm) and is expressed by a Wa value.
  • the cycle of the microwaviness as the measurement object is 0.1 to 5 mm.
  • the resulting magnetic disk substrate is used for the production of a magnetic disk in a customary manner. For example, texturing for forming texture grooves in a head traveling direction is first applied to the substrate, whenever necessary. Next, a base film made of a Cr alloy is formed by sputtering on this substrate. A magnetic recording layer made of a Co base alloy is formed to a thickness of about 10 to about 100 nm on this base film. A protective film of carbon, or the like, is preferably formed further on this magnetic recording layer to improve corrosion resistance, sliding resistance, etc. Hydrogenated carbon formed by sputtering or diamond-like carbon by CVD, for example, is formed to a film thickness of about 1 to about 50 nm as this carbon.
  • Perfluoropolyether or a product obtained by esterifying or amidating the terminals of the former is diluted with a solvent and is applied by spraying, dipping, spin coating, etc to a film thickness of about 0.5 to about 5 nm as a lubrication layer to the surface of this carbon protective film, and durability, reliability, etc can be further improved.
  • the head floating height on the magnetic disk can be decreased (low glide height) .
  • the head floating height on the magnetic disk is expressed by a glide avalanche value and by a floating height value of an inspection head when a protuberance portion of the magnetic disk starts impinging against the inspection head.
  • a glide avalanche value of 5.5 nm or below, preferably 5 nm or below and further preferably 3 nm or below can be obtained, for example.
  • Glide avalanche value glide height tester
  • the relation between the rotating speed of the magnetic disk and the head floating height was measured in advance. While the inspection head was kept fixed at an arbitrary radius position, the rotating speed of the magnetic disk was gradually changed. When a signal from the inspection head became high, the floating height could be determined from the rotating speed at that time. The rise point was defined as the glide avalanche value.
  • Example 1 A 2.5-in. lithium silicate type crystallized glass substrate was lapped. The plate accuracy was set to 150 ⁇ m by using diamond abrasives.
  • the glass substrate was processed at a number of revolutions of a plate of 15 rpm and a processing pressure of 100 g/cm 2 (about 9,806 Pa) until a predetermined thickness could be obtained.
  • a processing pressure of 100 g/cm 2 about 9,806 Pa
  • an end face on the inner circumferential side facing an inner diameter hole and an end face on the outer circumferential side were chamfered, respectively.
  • the main surface of the glass substrate was finally polished to a mirror surface.
  • the glass substrate was dried and the microwaviness and the degree of flatness (TIR) were measured. As a result, the microwaviness was 0.375 nin and the degree of flatness (TIR) was 4.98 ⁇ m.
  • Example 2 On the resulting glass substrate were formed serially by sputtering at a substrate temperature of 200°C a Cr film as a base layer to 60 nm, a COi 3 Cr 6 Pt 3 Ta alloy film as a magnetic recording layer to 20 nm and a diamond-like carbon film as a protective layer to 10 nm. Furthermore, a perfluoropolyether lubrication layer was applied by dipping to a thickness of 3 nm, giving a magnetic disk. The glide avalanche value of this magnetic disk was 5.5 nm.
  • Example 2 Example 2:
  • a glass substrate and a magnetic disk were produced in the same way as in Example 1 with the exception that plate accuracy was set to 60 ⁇ m.
  • the microwaviness of the glass substrate was 0.250 nm and its degree of flatness (TIR) was 2.30 ⁇ m.
  • TIR degree of flatness
  • the glide avalanche value of the magnetic disk was 5.0 nm. Comparative Example 1:
  • a glass substrate and a magnetic disk were produced in the same way as in Example 1 with the exception that plate accuracy was set to 750 ⁇ m.
  • the microwaviness of the glass substrate was 0.909 nm and its degree of flatness (TIR) was 10.04 ⁇ m.
  • TIR degree of flatness
  • the glide avalanche value of the magnetic disk was 6.25 nm. Comparative Example 2 :
  • a glass substrate and a magnetic disk were produced in the same way as in Example 1 with the exception that plate accuracy was set to 325 ⁇ m.
  • the microwaviness of the glass substrate was 0.744 nm and its degree of flatness (TIR) was 6.30 ⁇ m.
  • TIR degree of flatness
  • the glide avalanche value of the magnetic disk was 5.75 nm.
  • the invention provides a method capable of efficiently polishing a glass substrate so that its degree of flatness (TIR value) is 5 ⁇ m or below.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)
  • Magnetic Record Carriers (AREA)

Abstract

To reduce a head floating height on a magnetic disk, the invention provides a production method for a magnetic disk substrate capable of efficiently polishing the glass substrate until the degree of flatness (TIR value) of the glass substrate becomes 5 μm or below. The invention relates to a production method, for a magnetic disk substrate, by polishing a glass substrate by lapping by using a lap plate, characterized in that plate accuracy is set to 180 μm or below and polishing is carried out until a degree of flatness (TIR value) of the glass substrate becomes 5 μm or below. A magnetic disk is obtained by forming a magnetic recording layer on this magnetic disk substrate.

Description

DESCRIPTION
MAGNETIC DISK SUBSTRATE AND PRODUCTION METHOD OF
MAGNETIC DISK
CROSS-REFERENCES TO RELATED APPLICATIONS
This application is an application filed under 35 U.S.C. §111 (a) claiming benefit pursuant to 35 U. S.C. §119 (e) of the filing date of Provisional Application No. 60/606,416, filed September 2, 2004, pursuant to 35 U.S.C. §111 (b) .
TECHNICAL FIELD
This invention relates to a magnetic disk substrate and a production method of a magnetic disk.
BACKGROUND ART
Magnetic disk devices have made remarkable progress, as external storage devices of computers, owing to their superior cost/performance ratio and further growth is expected. In the magnetic disk devices, a magnetic head flies a predetermined height above a substrate surface when the magnetic disk rotates. This height has become smaller, with the recent requirement for a higher recording density, and the magnetic force of the magnetic head operates on only a small area of a magnetic thin film layer on the substrate and this makes it possible to achieve a higher density. On the other hand, the danger of mis-operations of the devices, due to contact between the magnetic head and the substrate surface, has become higher. To reduce the head floating height (to reduce the glide height) , the flatness of the surface of the magnetic disk is important.
An aluminum type substrate has been used in the past as a substrate of a magnetic disk which is mounted in the magnetic disk device, but glass substrates, made of chemically tempered glass and crystallized glass, have gradually gained a wider application because they have high impact resistance and can more easily be made flat. In other words, the aluminum type substrate can easily provide a magnetic disk having excellent magnetic characteristics but involves the problem of flatness because it suffers plastic deformation during a mechanical process such as polishing. In contrast, the glass substrate can be easily made flat because it has high surface hardness and does not involve the plastic deformation described above.
Various studies have been made in the past to reduce the head floating height of the magnetic disk. For example, a method that selects surface roughness of a polishing pad so that microwaviness of the glass substrate reaches a specific value has been proposed
(Japanese Unexamined Patent Publication (Kokai) No. 2002- 92867) . Another method sets the surface roughness of the glass substrate and its microwaviness to a predetermined range/relation (Japanese Unexamined Patent Publication (Kokai) No. 2002-163818) . Further, a glass substrate in which microwaviness of the surface has a cycle of 0.1 to 5 mm and amplitude of 0.1 to 1 nm has been proposed (Japanese Unexamined Patent Publication (Kokai) No. 2000- 207737) .
DISCLOSURE OF INVENTION
To reduce the head floating height of the magnetic disk, the invention provides a method capable of efficiently polishing a glass substrate so that its degree of flatness (TIR value) becomes 5 μm or below.
To solve the problems described above, the invention provides the following inventions.
(1) A production method of a magnetic disk substrate by polishing a glass substrate by lapping by using a lap plate, characterized in that plate accuracy is set to 180 μm or below and polishing is carried out until a degree of flatness (TIR value) of the glass substrate becomes 5 μm or below.
(2) The production method of a magnetic disk substrate as described in (1) , wherein plate accuracy is 150 μm or below. (3) The production method of a magnetic disk substrate as described in (2), wherein plate accuracy is 80 μm or below.
(4) The production method of a magnetic disk substrate as described in (3) , wherein plate accuracy is 50 μm. (5) The production method of a magnetic disk substrate as described in any of (1) through (4), wherein the degree of flatness (TIR value) of the glass substrate is 4 μm or below.
(6) The production method of a magnetic disk substrate as described in (5) , wherein the degree of flatness (TIR value) of the glass substrate is 3 μm or below.
(7) The production method of a magnetic disk substrate as described in any of (1) through (6), wherein a microwaviness value of the glass substrate is 0.5 nm or below.
(8) The production method of a magnetic disk substrate as described in (7), wherein the microwaviness value of the glass substrate is 0.3 nm or below.
(9) A production method of a magnetic disk characterized in that a magnetic recording layer is formed on the magnetic disk substrate as described in any of (1) through (8) .
(10) The production method of a magnetic disk as described in (9), wherein a glide avalanche value of the magnetic disk is 5.5 nm or below.
(11) The production method of a magnetic disk as described in (9), wherein a glide avalanche value of the magnetic disk is 3 nm or below.
(12) Α magnetic disk substrate for a magnetic disk, produced by a production method according to any of claims 1 through 8. (13) A magnetic disk produced using a magnetic disk substrate according to any of claims 9 through 11.
To reduce a head floating height of a magnetic disk, the present invention provides a method capable of efficiently conducting polishing so that a degree of flatness (TIR value) of a glass substrate is 5 μm or below.
BEST MODE FOR CARRYING OUT THE INVENTION In the production method of a magnetic disk substrate according to the invention, lapping accuracy is set to 180 μm or below and polishing is carried out until the degree of flatness (TIR value) of the glass substrate becomes 5 μm or below when the glass substrate is polished by lapping by using a lap plate.
Amorphous, chemically tempered or crystallized glass, that has generally been used for the magnetic disk substrate, can be used as the glass substrate in the invention. Examples are glasses such as soda lime, aluminosilicate, lithium silicate, lithium aluminosilicate, aluminoborosilicate glasses, and so forth. As the chemically tempered glass, glass that is brought into contact with a molten salt at a high temperature to cause ion exchange of alkali ions in the glass with different kinds of alkali ions in the molten salt and is tempered by the compressive stress is suitable. Examples of the crystallized glass are those which are obtained by re-heating glass under a controlled condition and precipitating and growing a large number of fine crystals . Concrete examples are an Al2O3-SiO2-Li2O type , a B2O3-Al2O3-SiO2-Li2O type , and so forth . The thickness of such glass substrates is generally selected from the range of about 0 . 1 to about 2 mm.
In the invention, polishing of the glass substrate is carried out by lapping using a lap plate until the degree of flatness (TIR value) is 5 μm or below, preferably 4 μm or below and further preferably 3 μm or below. Lapping is defined as a pre-process to polishing. Generally, in the case of amorphous and chemical tempered glass, lapping is carried out by abrading the glass substrate surface and the plate through free abrasives dispersed in water, etc. In the case of the crystallized glass, fixed abrasives such as diamond pellets or a diamond plate are used. Examples of the abrasives are aluminum oxide, zirconium oxide, silicon carbide and so forth, but aluminum oxide is suitable from the aspect of a polishing speed, etc. In the invention, lapping itself is carried out in a customary manner but it is necessary to set plate accuracy to 180 μm or below. Adjustment of plate accuracy itself can be done in a customary manner. Such plate accuracy is selected to preferably 150 μm or below, further preferably to 80 μm or below and most preferably 50 μm or below.
When lapping is conducted in the invention as described above, the degree of flatness (TIR value) of the resulting glass substrate can be easily set to 5 μm or below by setting plate accuracy to 180 μm or below. This degree of flatness (TIR value: Total Indicated Run¬ out) represents the measurement result of top/valley indicating the difference between the highest point and the lowest point on the substrate surface with respect to a plane that is most optimally fit.
After lapping is applied as described above, an end face of the glass substrate on the inner circumferential side facing an inner diameter hole and an end face on the outer circumferential side are respectively chamfered to give chamfer portions. The end faces of the glass substrate on both inner and outer circumferential sides processed in this way are subjected to polishing into mirror surfaces. Subsequently, the main surface of the glass substrate is finally polished to a mirror surface. Thereafter, the glass substrate is washed and dried in a customary manner and a magnetic disk glass substrate can be acquired.
By this polishing, the microwaviness value of the glass substrate can be easily reduced to 0.5 nm or below, preferably 0.3 nm or below. This microwaviness value means that having a corrugation substrate surface, a cycle in the order of mm and amplitude in the order of nm. It is measured by using an "OPTIFLAT" (product of ADE Phase Shift Co.) (filter 5mm) and is expressed by a Wa value. The cycle of the microwaviness as the measurement object is 0.1 to 5 mm.
The resulting magnetic disk substrate is used for the production of a magnetic disk in a customary manner. For example, texturing for forming texture grooves in a head traveling direction is first applied to the substrate, whenever necessary. Next, a base film made of a Cr alloy is formed by sputtering on this substrate. A magnetic recording layer made of a Co base alloy is formed to a thickness of about 10 to about 100 nm on this base film. A protective film of carbon, or the like, is preferably formed further on this magnetic recording layer to improve corrosion resistance, sliding resistance, etc. Hydrogenated carbon formed by sputtering or diamond-like carbon by CVD, for example, is formed to a film thickness of about 1 to about 50 nm as this carbon. Perfluoropolyether or a product obtained by esterifying or amidating the terminals of the former is diluted with a solvent and is applied by spraying, dipping, spin coating, etc to a film thickness of about 0.5 to about 5 nm as a lubrication layer to the surface of this carbon protective film, and durability, reliability, etc can be further improved.
When a magnetic disk is produced by using the magnetic disk substrate obtained in this way by the method of the invention, the head floating height on the magnetic disk can be decreased (low glide height) . The head floating height on the magnetic disk is expressed by a glide avalanche value and by a floating height value of an inspection head when a protuberance portion of the magnetic disk starts impinging against the inspection head. When the magnetic disk is produced by using the magnetic disk glass substrate according to the invention, a glide avalanche value of 5.5 nm or below, preferably 5 nm or below and further preferably 3 nm or below, can be obtained, for example.
Though the invention' will be explained in further detail with reference to Examples thereof, the invention is not limited to these Examples unless the invention exceeds the gist thereof.
In Examples, measurement of microwaviness and a degree of flatness (TIR value) of the substrate, plate accuracy and a glide avalanche value were carried out by using the following measuring apparatuses.
(1) Microwaviness: "OPTIFLAT" (product of ADE Phase Shift
Co. )
Cycle of waviness 0.1 to 5 mm (2) Degree of flatness (TIR value) : Laser interference meter type measuring instrument "Zygo" GPI-XP (product of
Zygo Co. )
(3) Plate accuracy: commercial plate flatness meter
(4) Glide avalanche value: glide height tester As for the measurement of the glide avalanche value, the relation between the rotating speed of the magnetic disk and the head floating height was measured in advance. While the inspection head was kept fixed at an arbitrary radius position, the rotating speed of the magnetic disk was gradually changed. When a signal from the inspection head became high, the floating height could be determined from the rotating speed at that time. The rise point was defined as the glide avalanche value. Example 1: A 2.5-in. lithium silicate type crystallized glass substrate was lapped. The plate accuracy was set to 150 μm by using diamond abrasives. The glass substrate was processed at a number of revolutions of a plate of 15 rpm and a processing pressure of 100 g/cm2 (about 9,806 Pa) until a predetermined thickness could be obtained. Next, an end face on the inner circumferential side facing an inner diameter hole and an end face on the outer circumferential side were chamfered, respectively. After the resulting end faces on both inner and outer circumferential sides were polished to mirror surfaces, the main surface of the glass substrate was finally polished to a mirror surface. After being washed, the glass substrate was dried and the microwaviness and the degree of flatness (TIR) were measured. As a result, the microwaviness was 0.375 nin and the degree of flatness (TIR) was 4.98 μm. On the resulting glass substrate were formed serially by sputtering at a substrate temperature of 200°C a Cr film as a base layer to 60 nm, a COi3Cr6Pt3Ta alloy film as a magnetic recording layer to 20 nm and a diamond-like carbon film as a protective layer to 10 nm. Furthermore, a perfluoropolyether lubrication layer was applied by dipping to a thickness of 3 nm, giving a magnetic disk. The glide avalanche value of this magnetic disk was 5.5 nm. Example 2:
A glass substrate and a magnetic disk were produced in the same way as in Example 1 with the exception that plate accuracy was set to 60 μm. The microwaviness of the glass substrate was 0.250 nm and its degree of flatness (TIR) was 2.30 μm. On the other hand, the glide avalanche value of the magnetic disk was 5.0 nm. Comparative Example 1:
A glass substrate and a magnetic disk were produced in the same way as in Example 1 with the exception that plate accuracy was set to 750 μm. The microwaviness of the glass substrate was 0.909 nm and its degree of flatness (TIR) was 10.04 μm. On the other hand, the glide avalanche value of the magnetic disk was 6.25 nm. Comparative Example 2 :
A glass substrate and a magnetic disk were produced in the same way as in Example 1 with the exception that plate accuracy was set to 325 μm. The microwaviness of the glass substrate was 0.744 nm and its degree of flatness (TIR) was 6.30 μm. On the other hand, the glide avalanche value of the magnetic disk .was 5.75 nm.
INDUSTRIAL APPLICABILITY To reduce a head floating height on a magnetic disk, the invention provides a method capable of efficiently polishing a glass substrate so that its degree of flatness (TIR value) is 5 μm or below.

Claims

1. A production method for a magnetic disk substrate by polishing a glass substrate by lapping using a lap plate, characterized in that plate accuracy is set to 180 μm or below and polishing is carried out until a degree of flatness (TIR value) of said glass substrate becomes 5 μm or below.
2. The production method of a magnetic disk substrate according to claim 1, wherein plate accuracy is 150 μm or below.
3. The production method of a magnetic disk substrate according to claim 2, wherein plate accuracy is 80 μm or below.
4. The production method of a magnetic disk substrate according to claim 3, wherein plate accuracy is 50 μm or below.
5. The production method of a magnetic disk substrate according to any of claims 1 through 4, wherein the degree of flatness (TIR value) of said glass substrate is 4 μm or below.
6. The production method of a magnetic disk substrate according to claim 5, wherein the degree of flatness (TIR value) of said glass substrate is 3 μm or below.
7. The production method of a magnetic disk substrate according to any of claims 1 through 6, wherein a microwaviness value of said glass substrate obtained by polishing is 0.5 nm or below.
8. The production method of a magnetic disk substrate according to claim 7, wherein the microwaviness value of said glass substrate is 0.3 nm or below.
9. A production method of a magnetic disk characterized in that a magnetic recording layer is formed on said magnetic disk substrate according to any of claims 1 through 8.
10. The production method of a magnetic disk according to claim 9, wherein a glide avalanche value of said magnetic disk is 5.5 nm or below.
11. The production method of a magnetic disk according to claim 9, wherein a glide avalanche value of said magnetic disk is 3 nm or below.
12. A magnetic disk substrate for a magnetic disk, produced by a production method according to any of claims 1 through 8.
13. A magnetic disk produced using a magnetic disk substrate according to any of claims 9 through 11.
PCT/JP2005/016049 2004-08-27 2005-08-26 Magnetic disk substrate and production method of magnetic disk Ceased WO2006022443A1 (en)

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JP2004-248568 2004-08-27
US60641604P 2004-09-02 2004-09-02
US60/606,416 2004-09-02

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US7855002B2 (en) * 2005-12-15 2010-12-21 Showa Denko K.K. Magnetic disk substrate and magnetic recording medium thereof
CN102653074A (en) * 2011-03-01 2012-09-05 旭硝子株式会社 Method for polishing glass plate
CN103456321A (en) * 2010-02-01 2013-12-18 旭硝子株式会社 Glass substrate for magnetic recording medium

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JP4411331B2 (en) * 2007-03-19 2010-02-10 信越化学工業株式会社 Silicon substrate for magnetic recording medium and manufacturing method thereof
JP2009134802A (en) * 2007-11-29 2009-06-18 Furukawa Electric Co Ltd:The Glass substrate for magnetic disk and magnetic disk device
US8603350B2 (en) * 2009-07-17 2013-12-10 Ohara Inc. Method of manufacturing substrate for information storage media
JP5307094B2 (en) * 2009-09-30 2013-10-02 Ｈｏｙａ株式会社 Information recording medium substrate glass blank, information recording medium substrate, information recording medium manufacturing method, and information recording medium substrate glass blank manufacturing apparatus
CN106297833B (en) * 2009-12-29 2019-03-08 Hoya株式会社 The manufacturing method and glass substrate for disc of glass substrate for disc
US20180245638A1 (en) * 2017-02-28 2018-08-30 Caterpillar Inc. Method for coating a component
JP7113157B1 (en) * 2022-03-30 2022-08-04 古河電気工業株式会社 Magnetic disk and substrate for magnetic disk
US12437781B2 (en) 2022-09-28 2025-10-07 Western Digital Technologies, Inc. Glass sheet for fabricating magnetic recording media and method of fabricating magnetic recording media

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002092867A (en) * 2000-09-21 2002-03-29 Hoya Corp Method of manufacturing glass substrate for information recording medium and method of manufacturing information recording medium
JP2002163818A (en) * 2000-10-19 2002-06-07 Hoya Corp Substrate for information recording medium, information recording medium and method for controlling substrate surface in information recording medium

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020009602A1 (en) * 2000-03-13 2002-01-24 Hoya Corporation Method and apparatus of fabricating glass molded article, method of fabricating glass substrate, and information recording medium
JP2003160348A (en) * 2001-11-21 2003-06-03 Nippon Sheet Glass Co Ltd Glass substrate for information recording medium and its manufacturing method

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002092867A (en) * 2000-09-21 2002-03-29 Hoya Corp Method of manufacturing glass substrate for information recording medium and method of manufacturing information recording medium
JP2002163818A (en) * 2000-10-19 2002-06-07 Hoya Corp Substrate for information recording medium, information recording medium and method for controlling substrate surface in information recording medium

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7855002B2 (en) * 2005-12-15 2010-12-21 Showa Denko K.K. Magnetic disk substrate and magnetic recording medium thereof
CN103456321A (en) * 2010-02-01 2013-12-18 旭硝子株式会社 Glass substrate for magnetic recording medium
CN102653074A (en) * 2011-03-01 2012-09-05 旭硝子株式会社 Method for polishing glass plate

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