JPH09326115A - Magnetic disk device and production of magnetic disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high recording density and to improve reliability by using a magnetic disk substrate effective for low floating of a magnetic head. SOLUTION: The magnetic disk substrate 1 formed by subjecting the surface of an aluminum alloy to nickel-phosphorus plating, polishing and texturing is used. A ground surface film 2 consisting of Cr, etc., a magnetic film 3 consisting of a Co alloy, a protective film 4 consisting of carbon thickness., and a fluorine lubricating film 5 are formed on the surface of the substrate 1. The substrate 1 has a undulating shape having a wavelength of the length below the external shape size in the longitudinal direction of the slider of the magnetic head for reading and writing information from and to a magnetic disk and a rough shape of a wavelength of <=1/3 the wavelength of this undulating shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device used for a storage device and the like and a method of manufacturing a magnetic disk used for the same.

[0002]

2. Description of the Related Art Conventionally, as a magnetic disk substrate, an aluminum alloy surface is plated with nickel-phosphorus, and the surface is polished, and the surface of the substrate is roughened by texturing using abrasive grains. There is. The concavo-convex shape is formed substantially concentrically with respect to the substrate, and the convex portion has a continuous ridge shape. As a conventional technique relating to texture processing, for example, Japanese Patent Application Laid-Open No. 3-125325 can be cited. This publication describes a technique for preventing sticking by further providing a crossing angle with respect to a ridge portion formed on substantially concentric circles to form unevenness.

[0003]

In order to increase the recording capacity of the magnetic disk device, it is required to reduce the flying height (flying height) of the magnetic head, for example, to make it narrower than 100 nm. The surface roughness of the textured surface is
The surface state is slightly larger than the surface roughness of the processed surface obtained by polishing the nickel-phosphorus plated surface. Therefore, in order to reduce the flying height, it is necessary to reduce the surface roughness of the textured surface. However, since the magnetic disk substrate has undulations with a wavelength longer than this surface roughness, the flying height was not as small as the measured value of the surface roughness.

The prior art described above has a problem in that it is difficult to reduce the flying height of the magnetic head because the surface roughness and the undulation of a longer wavelength than that are not taken into consideration.

A first object of the present invention is to provide a magnetic disk device capable of improving recording density and reliability by lowering the flying height of a magnetic head. A second object of the present invention is to provide a method of manufacturing a magnetic disk suitable for manufacturing the magnetic disk of such a magnetic disk device.

[0006]

In order to achieve the first object, the magnetic disk device of the present invention has a magnetic disk substrate used for the magnetic disk device for reading and writing information from and on the magnetic disk. The magnetic head slider has a wavy shape having a wavelength of a length equal to or less than the outer dimension of the slider in the longitudinal direction, and a roughness shape having a wavelength of 1/3 or less of the wavelength of the waviness.

The wavelength of the waviness is less than or equal to the outer dimension of the slider of the magnetic head in the longitudinal direction, and is preferably 10 μm or more. The longitudinal direction of the slider generally corresponds to the circumferential direction of the magnetic disk. Further, the roughness shape is preferably ⅓ or less of the wavelength of the above waviness, and preferably 20 nm or more.

The amplitude of the waviness is 1 to 6 nm.
Is preferable, and the range of 1 to 5 nm is more preferable. The surface roughness Rp of the roughness shape is 1
To 8 nm, preferably 2 to 8 nm
More preferably, it is within the range.

Further, in order to achieve the second object,
The method for manufacturing a magnetic disk of the present invention is one in which a processing tape is pressed against a magnetic disk substrate, and when texture processing is performed using abrasive grains, a processing tape having periodic irregularities in its lateral direction is used. Due to this unevenness, a wavy shape having a wavelength equal to or smaller than the outer dimension of the slider of the magnetic head in the longitudinal direction is formed on the magnetic disk substrate.

In the case of periodic irregularities in the lateral direction of the processing tape, both the concave portions and the convex portions extend in the longitudinal direction of the tape. The concave portions and the convex portions may extend straight in the longitudinal direction of the tape, or may extend at a certain angle. The pitch of the irregularities is preferably equal to or smaller than the outer dimension of the slider of the magnetic head in the longitudinal direction.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a magnetic disk used in the present invention. As described above, the surface of the magnetic disk substrate 1 which has been subjected to nickel-phosphorus plating on the surface of the aluminum alloy, polished, and textured by the method to be described later in detail is provided with a base film 2 of Cr or the like, a magnetic film 3 of a Co alloy, carbon or the like. The protective film 4 and the fluorine-based lubricating film 5 are formed. The surface shape of the magnetic disk substrate after forming the magnetic film or the protective film does not change because the substrate shape before film formation remains. Therefore, when the protrusion is formed on the substrate, the shape of the protrusion on the surface of the magnetic disk is defined.

FIG. 10 is a perspective view of the magnetic disk device of the present invention. Stacking several magnetic disks 80,
Magnetic heads 81 are arranged facing the respective surfaces. The magnetic head 81 is positioned on the magnetic disk 80 by the drive mechanism 82.

First, the flying property of the magnetic head 6 with respect to the magnetic disk 1'will be described with reference to FIG. FIG.
As shown in (a), the shape 9 of the magnetic disk 1 ′ with respect to the magnetic head 6 is the wavy shape 7 of the wavelength L (see FIG.
(B)) and a roughness profile 8 with a shorter wavelength (see FIG. 2).
It is considered that it is formed by the overlapping shape with (b)).

In order to reduce the clearance between the magnetic disk 1'and the magnetic head 6, the surface shape of the magnetic disk 1'is as shown in FIG.
A method of setting it to 0, or a method of combining a shape 11 having an extremely small waviness amplitude and a method of reducing roughness as shown in FIG.

The magnetic disk may have a CSS zone for contact start / stop of the magnetic head separately from the data zone. However, the above-mentioned waviness and roughness may be applied to the data zone.

Next, a method of processing the shape of the magnetic disk substrate will be described with reference to FIG. The processing tape 14 is pressed by the rubber roller 15 onto the magnetic disk substrate 1 that has been nickel-phosphorus plated and polished, the diamond slurry is dropped on the processing tape 14 to rotate the magnetic disk 1, and the processing tape 14 is fed. A processing load is applied to form a substantially concentric circular texture.

In the groove processing called texture on the magnetic disk substrate, the abrasive particles are scratched by the pressing and relative sliding of the abrasive particles to the magnetic disk, and are formed as a surface shape. It is considered that the mechanical action of the abrasive grains as the working liquid is affected by the particle diameter of the abrasive grains, the pressing pressure, and the supporting rigidity of the working tape that supports the abrasive grains. The pressing pressure of fine abrasive grains is not determined only by the load applied to the entire polishing cloth, but microscopically determined by the hardness of the polishing cloth supporting the abrasive grains.

Further, pay attention to the surface shape of the processing tape. The surface shape of the processing tape has unevenness, and the unevenness of the tape surface causes a difference in mechanical processing action, and the difference in the processing amount is transferred to the substrate shape to form a waviness shape and a roughness shape. The magnetic disk substrate can be formed into a smoother shape than before by reducing the difference in the amount of processing.

A model for forming the surface shape of the magnetic disk substrate will be described with reference to FIG. Consider a shape forming model in which the surface shape 16 of the processed tape is transferred to the texture shape 17.
Abrasive grains of diamond slurry are held on the processing tape 14 to form grooves on the surface of the substrate. It is considered that the surface shape 16 of the processing tape 14 causes a difference in support rigidity of the abrasive grains, and the waviness shape of the processing tape 14 is transferred to the waviness shape of the magnetic disk substrate.

FIG. 5 shows the waviness shape transferability to the processed tape-shaped magnetic disk substrate. The processed tape was embossed to form a surface shape 18 having a pitch of 300 μm as shown in the plan view and the sectional view of FIGS. 5 (a) and 5 (b). The undulation shape of this textured surface was investigated. The waviness of the processed surface is WYKO TOP of an optical shape measuring instrument.
It was measured using O-3D. FIG. 5 (d) shows the Fourier-transformed power spectrum of the wavy shape (FIG. 5 (c)) of the magnetic disk substrate. 300 μm of processed tape
As shown in Fig. 5 (d), the embossed shape of the pitch is 30
It is transferred to the substrate as a undulating shape with a pitch of 0 μm, as shown in FIG.
A shape including periodicity with an amplitude of 5 nm shown in (c) is formed.

In this way, the waviness of the processed tape can be transferred to the waviness of the magnetic disk substrate. That is, it was found that the surface shape of the magnetic disk substrate was formed by unevenly pressing the abrasive grains into the magnetic disk substrate.

FIG. 6 shows the influence of the working abrasive grain size on the waviness of the substrate. There is a correlation between the average abrasive grain size of the processing slurry and the waviness amplitude under a constant processing load of 1.5 kg.
It can be seen that miniaturization of the abrasive grains is effective in reducing the substrate waviness amplitude.

FIG. 7 shows the influence of the processing load and the average abrasive grain size on the waviness of the substrate. The processing load and the average abrasive grain size have a correlation with the substrate waviness amplitude. In order to reduce the substrate waviness amplitude, a method of reducing the processing load or a method of refining the abrasive grains is effective.

As shown in FIG. 8A, description will be given of a case where the groove shape of the processed tape is an embossed shape having an angle with respect to the processing tape feeding direction during processing. In this case, the power spectrum obtained by Fourier series conversion of the waviness shape of the magnetic disk substrate (FIG. 8B) is shown in FIG. 8C.
Shown in As can be seen from the power spectrum, the periodic waviness disappears, and the waviness of the magnetic disk substrate has an amplitude of 3 nm or less, and the waviness is smoothed.

FIG. 9 shows the relationship between the waviness amplitude and the surface roughness of the magnetic disk substrate according to the conventional processing method and the present invention.
The waviness of the substrate is measured by the optical surface profilometer WYKO.
By using TOPO-3D manufactured by Co., Ltd. and using an objective lens of 1.5 times, a 6.7 mm square area was quantified. A stylus surface roughness meter, Thera Hobson Nanostep, was used for surface roughness profile measurement, and the measurement length was 80 μm, and the wavelength was 8
The surface roughness shape within 0 μm was quantified. The magnetic disk manufactured by the conventional processing method has a waviness amplitude of 5 nm to 9 nm and a surface roughness profile Rp of 10 nm to 18 nm. The magnetic disk of the present invention has a waviness amplitude of 1 nm to 6 n.
m, surface roughness profile Rp 1 nm to 8 nm.

A magnetic disk was manufactured using these magnetic disk substrates, and the flying property of the magnetic head was measured. The result is shown in FIG. It is shown that the magnetic disk of the present invention has a smooth shape that is favorable for low flying height.

Although an aluminum alloy is used for the substrate in the above embodiment, substantially the same effect can be obtained by using, for example, a substrate obtained by plating glass with nickel phosphorus.

[0028]

As described above, the magnetic disk device of the present invention can improve the high recording density and the reliability by using the magnetic disk substrate effective for lowering the flying height of the magnetic head. . Further, the magnetic disk manufacturing method of the present invention reduces the waviness of the magnetic disk substrate,
The undulation shape and surface roughness shape could be controlled on the order of nanometer. By using this magnetic disk substrate, a magnetic disk effective for lowering the flying height of the magnetic head could be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of a magnetic disk used in the present invention.

FIG. 2 is an explanatory diagram of flying of a magnetic head with respect to a magnetic disk.

FIG. 3 is a schematic diagram of a magnetic disk substrate processing apparatus to which the present invention is applied.

FIG. 4 is an explanatory view of forming a surface shape of a magnetic disk substrate according to the present invention.

5A and 5B are a plan view and a sectional view of a processed tape used in the present invention, a shape explanatory view thereof, and a shape explanatory view of a magnetic disk substrate.

FIG. 6 is a diagram showing the relationship between the average abrasive grain size of the slurry and the waviness amplitude of the magnetic disk substrate.

FIG. 7 is a diagram showing the relationship between the processing load and the waviness amplitude of the magnetic disk substrate.

FIG. 8 is a plan view of a processed tape used in the present invention, a shape explanatory view thereof, and a shape explanatory view of a magnetic disk substrate.

FIG. 9: Waviness amplitude and surface roughness Rp of magnetic disk substrate
Relationship diagram with.

FIG. 10 is a configuration diagram of an embodiment of a magnetic disk device of the present invention.

FIG. 11 is a diagram showing the relationship between the waviness and roughness of the magnetic disk and the flying height of the magnetic head.

[Explanation of symbols]

 1 ... Magnetic disk substrate 1 ', 80 ... Magnetic disk 2 ... Underlayer film 3 ... Magnetic film 4 ... Protective film 5 ... Lubrication film 6, 81 ... Magnetic head 7 ... Wavy shape 8 ... Roughness shape 9, 10, 11 ... Shape 14 ... Processing tape 15 ... Rubber roller 16 ... Surface shape of processing tape 17 ... Texture shape 18 ... Surface shape 82 ... Drive mechanism

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Kikuchi 2880 Kozu, Odawara City, Kanagawa Stock Company Hitachi Storage Systems Division

Claims (3)

[Claims] 1. A magnetic disk device comprising a magnetic disk, a magnetic head for reading / writing information from / to the magnetic disk, and a drive mechanism for positioning the magnetic head on the magnetic disk. A data zone of a substrate of the magnetic disk. The magnetic disk has a wavy shape having a wavelength of a length equal to or less than the outer dimension of the slider of the magnetic head in the longitudinal direction, and a roughness shape having a wavelength of 1/3 or less of the wavelength of the waviness. apparatus. 2. The amplitude of the waviness is in the range of 1 to 6 nm, and the surface roughness Rp of the roughness is 1 to 8.
2. The magnetic disk device according to claim 1, wherein the magnetic disk device has a range of nm. 3. A method of manufacturing a magnetic disk, comprising: a step of preparing a magnetic disk substrate; and a step of pressing a processing tape against the magnetic disk substrate and performing texture processing using abrasive grains. Forming a waviness shape having a wavelength equal to or smaller than the outer dimension in the longitudinal direction of the slider of the magnetic head for reading and writing information on the magnetic disk by the unevenness. And a method for manufacturing a magnetic disk.