JPH11144238A - Manufacturing method of magnetic recording medium - Google Patents

Abstract

(57) [Summary] (With correction) [PROBLEMS] In manufacturing a magnetic recording medium, different textures are formed in a substrate portion serving as a CSS region and a substrate portion serving as a data recording region. SOLUTION: When texture processing is performed on a substrate 1 by a slurry grinding method, different abrasive grains are supplied to a substrate portion serving as a CSS region and a substrate portion serving as a data recording region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium in which a magnetic recording layer is formed on a substrate after texturing. In particular, the present invention relates to an improved texture processing method.

[0002]

2. Description of the Related Art In recent years, magnetic recording media such as magnetic disks have been widely used as external storage devices with the development of information processing technologies such as computers. The most widely used magnetic disk consists of a non-magnetic plating of Ni-P on an aluminum alloy substrate, an underlayer of Cr or the like, a magnetic layer of a Co-based alloy, and a carbonaceous protective layer. A magnetic recording layer is formed.

[0003] With the increase in the density of the magnetic disk, the distance between the magnetic disk and the magnetic head, that is, the flying height is becoming smaller and smaller, and recently, 0.10 µm or less is required. In addition, miniaturization has been promoted in parallel with the increase in the density of the magnetic disk, and the motor for rotating the spindle has become smaller. As a result, there is a possibility that the torque of the motor is insufficient, and a phenomenon that the magnetic head does not fly while being fixed to the magnetic disk surface at the time of startup is caused.
Also, during operation, the magnetic head comes in contact with the magnetic disk,
Normal rotation may be hindered due to frictional resistance.

[0004]

As means for preventing these phenomena from occurring, a surface treatment called texture processing for forming fine irregularities on the substrate surface of a magnetic disk has been performed. As a texture processing method, a tape grinding method using a fixed abrasive type polishing tape (Japanese Patent Application Laid-Open No. 1-86320) or a slurry grinding method using a slurry containing free abrasive particles adhered to the polishing tape (Japanese Patent Application Laid-Open No. No. 147518) is known.

[0005] The magnetic disk is composed of two parts having different functions, an inner peripheral part called a CSS area and an outer peripheral part called a data recording area. The CSS area is a starting point of the magnetic head, and it is preferable that the unevenness formed by the texture processing is relatively large in order to overcome the static friction and smoothly start the magnetic head. On the other hand, in the data recording area, it is desirable that the irregularities formed by the texture processing be as small as possible, as long as normal rotation is not hindered by adsorption of the magnetic head and the magnetic disk. An object of the present invention is to provide a method for manufacturing a magnetic recording medium having different textures in a CSS area and a data recording area with high productivity.

[0006]

According to the present invention, there is provided a method of manufacturing a magnetic recording medium in which a substrate is textured and a magnetic recording layer is formed on the substrate. Is performed while supplying slurry containing abrasive grains thereto, and by making the abrasive grains in the slurry different between a substrate portion serving as a CSS region and a substrate portion serving as a data recording region of a magnetic recording medium, C
A magnetic recording medium having a texture suitable for each of the SS area and the data recording area can be manufactured with high productivity.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, as the substrate, any substrate that can be used as a substrate for a magnetic recording medium can be used. Most commonly, an aluminum alloy surface is mirror-finished, and an electroless plating layer of a non-magnetic metal, for example, a Ni-P alloy or a Ni-Cu-P alloy, is formed on the aluminum alloy to a thickness of about 5 to 20 μm. The surface is further mirror-finished to have a surface average roughness Ra of 50 ° or less, preferably 30 ° or less by polishing.

In the present invention, the substrate is textured by a slurry grinding method using a polishing tape and a slurry containing abrasive grains. In this method, a texture is formed on a substrate by bringing a polishing tape into contact with a substrate and supplying a slurry containing abrasive grains to the substrate while rotating the substrate. In the present invention, two types of slurries each containing different abrasive grains are used, and one of them is supplied to a substrate portion serving as a CSS region of a magnetic recording medium, and the other is supplied to a substrate portion serving as a data recording region.

Conventional abrasives such as alumina, silicon carbide and diamond can be used as the abrasive grains. The grain size of the abrasive grains is preferably about 0.1 to 5 μm. As described above, the texture of the data recording area is preferably finer than that of the CSS area.
It is preferred to supply abrasive particles of smaller particle size. For example, CS
The average grain size (D50) is 1.7 in the portion of the substrate which becomes the S region.
μm abrasive grains are supplied, and abrasive grains having an average particle diameter of 1.0 μm are supplied to a substrate portion serving as a data recording area. At this time, it should be noted that the slurry supplied to the substrate portion serving as the CSS region does not move to the substrate portion serving as the data recording region. If this movement occurs, the texture of the data recording area will not be as fine as desired.

One means for preventing the slurry supplied to the substrate portion serving as the CSS region from moving to the substrate portion serving as the data recording region is to minimize the supply amount of the slurry and supply the slurry onto the polishing tape. In that part. According to the study of the present inventors, C
The supply amount of the slurry to the substrate portion to be the SS region is set to about 0.
03 ml / cm ² min or less, ie, normal diameter 9
In the case of a magnetic disk having a diameter of 5 mm, a central opening having a diameter of 25 mm, and a CSS region having a radius of 16.5 mm to 19.5 mm from the center, a slurry supply rate of 0.1 ml / min or less, for example, 0.05 to 0.1 mm. If it is 1 ml / min,
The slurry does not move to the data recording area.

In order to continuously supply such a very small amount of slurry onto the polishing tape, as shown in FIG. 1, the slurry is supplied to a head tank by a slurry pump to overflow the excess, and The tip of the slurry supply pipe from above to the polishing tape may be brought into contact with the polishing tape. According to this method, the supply amount of the slurry to the polishing tape can be easily controlled by adjusting the height of the head tank without pulsation of the supply amount as in the case of directly supplying by the pump. .
The supply position of the slurry on the polishing tape is slightly inside the CSS region in consideration of the bleeding of the slurry.

On the other hand, the slurry supplied to the substrate portion serving as the data recording region may move to the substrate portion serving as the CSS region. Therefore, the slurry may be supplied to the substrate portion serving as the data recording area by the slurry supply method in the ordinary slurry grinding method. However, if a large amount of slurry is directly supplied onto the polishing tape, the water in the polishing tape becomes excessive, and the slurry supplied to the portion that becomes the CSS region may move to the portion that becomes the data recording region. It costs. Normally, at least 0.1 ml / mi per 1 cm ^{2 of the} substrate portion serving as the data recording area
A slurry of n, preferably at least 0.17 ml / min, is provided directly on the substrate.

In the present invention, texture processing can be performed according to a conventional method, except that different abrasive grains are supplied in a slurry state to a portion serving as a CSS region and a portion serving as a data recording region of the substrate. FIG. 1 shows an example of a typical texture processing method. In FIG.
Polishing is performed by pressing four polishing tapes 2 with contact rollers 3 on both the front and back surfaces of the disk substrate rotating at 300 rpm. The contact roller 3 is shown in FIG.
As shown in FIG. 2B, the pressing cylinder 4 presses the polishing tape 2 against the surface of the substrate 1 with a predetermined force. The polishing tape 2 is 0.1 to 10 m in the direction of arrow B.
Running slowly at m / sec, the substrate is polished while always in contact with the new tape surface. Polishing tape 2
Is reciprocating (vibrating) at a rate of 50 times / min or more, preferably 100 to 5000 times / min in the direction of arrow C due to the reciprocating motion of the contact roller 3, and as a result, the striations ( The polishing marks) form an intersection angle (cross angle) of about 10 to 40 °. The tip of the slurry supply nozzle 5 is in contact with the inner part of the polishing surface of the polishing tape 2, that is, the part that contacts the CSS area of the substrate, and a small amount of slurry for polishing the CSS area is used. Is always supplied onto the polishing tape 2. On the other hand, a slurry for polishing a portion to be a data recording area of the substrate is supplied directly onto the substrate 1 via the slurry supply nozzle 6. The abrasive grain concentration of the slurry is 0.05 to 1.0% by weight for each slurry.
And the slurry usually contains a grinding oil and other conventional auxiliaries.

The surface condition of the substrate after the texture processing greatly depends on the grain size of the abrasive grains used.
The average roughness Ra is 65 ° and the maximum protrusion height is 280 ° in a portion to be the SS region, and the average roughness Ra is 45 ° and the maximum protrusion height is 150 ° in the portion to be the data recording region.
The textured substrate may be further subjected to a texture finishing process if desired, whereby the characteristics of the magnetic disk finally obtained can be further improved. This texture finishing may be performed using free abrasive grains as described above, or may be performed using a fixed abrasive type polishing tape such as a white alumina type or green carbon type. If desired, only polishing with a polishing tape without using abrasive grains may be performed, but in this case, the effect is naturally small. This texture finish processing
Surface average roughness R formed by the above texture processing
This operation is to reduce the maximum projection roughness Rp by crushing or otherwise removing projections such as burrs and burrs on the substrate surface without substantially changing a and the cross angle.

A magnetic recording layer is then formed on the substrate that has been subjected to the above-described texture processing and, if desired, texture finishing processing, to obtain a magnetic recording medium. The formation of the magnetic recording layer may be carried out by a conventional method. Usually, an underlayer, a magnetic layer, and a protective layer are sequentially formed by sputtering, and a lubricant is applied on the protective layer to form a lubricating layer. The underlayer is usually formed of chromium and has a thickness of about 50 to 2000 °. The magnetic layer is made of Co-Cr, Co-Ni, Co-Cr-
It is preferable to use a Co-based alloy such as X, Co-Ni-X, or Co-WX. In the above, X is Li,
Si, Ca, Ti, V, Cr, Ni, As, Y, Zr,
Nb, Mo, Ru, Rh, Ag, Sb, Hf, Ta,
W, Re, Os, Ir, Pt, Au, La, Ce, P
At least one element selected from the group consisting of r, Nd, Pm, Sm, and Eu. The thickness of the magnetic layer is 100 to 1
It is about 000Å. The protective layer is preferably carbonaceous, and is usually sputtered with carbon as a target under an atmosphere of a rare gas such as argon or helium, or in the presence of a small amount of hydrogen to form an amorphous carbon film or hydrogenated carbon. A film or the like is formed. The thickness of the protective layer is about 50 to 500 °. As the lubricant applied to the protective layer, a perfluoropolyether-based lubricant may be used so as to have a thickness of about 10 to 20 °.

[0016]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. Example 1 A substrate for a magnetic disk having a diameter of 95 mm in which a Ni-P electroless plating layer was formed on an aluminum alloy was textured by the method shown in FIG. To a substrate portion (19.5 to 21.5 mm from the center) serving as a CSS region, diamond abrasive grains having an average particle diameter of 2 μm were supplied as slurry to a polishing tape at a rate of 0.05 ml / min. Diamond abrasive grains having an average particle size of 0.5 μm were directly supplied as slurry to the substrate portion serving as a recording area at a rate of 10 ml / min. The surface average roughness (Ra) of the substrate after the texture processing is about 3 in the substrate portion serving as the CSS region.
0 to 65 ° (the average roughness decreases from the inner side to the outer side), and about 30 ° in the substrate portion serving as the data recording area.

Example 2 A substrate was textured in the same manner as in Example 1 except that the diamond abrasive grains supplied to the substrate portion serving as the data recording area were changed to those having an average particle diameter of 1 μm. The surface average roughness (Ra) of the obtained substrate was about 45 to 65 ° in the substrate part serving as the CSS area and about 45 ° in the substrate part serving as the data recording area.

Example 3 A slurry of diamond abrasive particles having an average particle diameter of 2 μm was formed on a polishing tape in a substrate portion serving as a CSS region by 0.1 ml /
min, and diamond abrasive grains having an average particle diameter of 1 μm were directly supplied as slurry at a rate of 10 ml / min to the substrate portion serving as a data recording area on the substrate.
The substrate was textured in the same manner as in Example 1.
The surface average roughness (Ra) of the obtained substrate was 19
Approximately 65 ° at a position of 25 mm, approximately 55 ° at a position of 21 mm, 2
It changed to about 45 ° at the position of 3 mm, and the average roughness of the inner part of the data recording area was deteriorated.

[Brief description of the drawings]

FIG. 1A is a front view of an example of an apparatus used for polishing a substrate in the present invention. (B): side view of the device of FIG. 1 (a).

FIG. 2 is an example of a slurry supply device used for polishing a substrate portion serving as a CSS region in the present invention.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 polishing tape 3 contact roller 4 holding cylinder 5 slurry supply nozzle 6 slurry supply nozzle 7 slurry head tank 8 slurry circulation pump 9 slurry tank

Claims (6)

[Claims] In a method of manufacturing a magnetic recording medium, wherein a substrate is subjected to texturing and a magnetic recording layer is formed thereon, the texturing is performed by bringing a polishing tape into contact with a rotating substrate and including abrasive grains. By performing while supplying the slurry, and by making the abrasive grains in the slurry different between the substrate portion serving as the CSS region and the substrate portion serving as the data recording region of the magnetic recording medium, the texture formed in each portion is different. The method characterized by making it. 2. The method according to claim 1, wherein the abrasive particles supplied to the substrate portion serving as the CSS area have a larger particle diameter than the abrasive particles supplied to the substrate portion serving as the data recording region. . 3. The abrasive grain supplied to a substrate portion serving as a CSS area and the abrasive grain supplied to a substrate portion serving as a data recording area are both diamonds. Method. 4. The supply of abrasive grains to each substrate portion,
A slurry containing abrasive grains is supplied to a polishing tape on a substrate portion to be a CSS area, and a slurry containing abrasive grains is directly supplied onto a substrate to a substrate portion to be a data recording area. The method according to claim 1. 5. The method according to claim 4, wherein the supply amount of the slurry containing the abrasive grains to the substrate portion serving as the CSS region is 0.03 ml / cm ² · min or less. 6. A supply rate of slurry containing abrasive grains to a substrate portion to be a data recording area is 0.1 ml / cm ² · min.
The method according to claim 4 or 5, wherein