JPH05290368A - Manufacture of magnetic disk - Google Patents

Abstract

PURPOSE:To obtain a magnetic disk having good durability by subjecting a nonmagnetic substrate to grinding with a polishing tape of a fixed abrasive grain type, then to texturing by using a slurry prepd. by mixing and dispersing abrasive grains for grinding having prescribed properties with and into a grinding liquid. CONSTITUTION:The magnetic disk is produced by texturing the surface of the nonmagnetic substrate, then laminating a magnetic layer thereon. The nonmagnetic substrate is subjected to >=1 times of the grinding by the polishing tape formed by fixing the abrasive grains for grinding to a tape and is then further subjected to >=1 times of the grinding while the slurry prepd. by mixing the abrasive grains for grinding having the Knoop hardness ranging from 1000 to 6000 with the polishing liquid and stirring the liquid mixture is dropped between the buff tape and the magnetic disk as the texturing method at the time of such production. The magnetic disk with which the low floating of a magnetic head is possible and which is good on both characteristics of a gliding characteristic and weatherability is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic disk used in a fixed magnetic disk device, and more specifically, fine processing on the surface of a magnetic disk using a polishing tape which is fixed abrasive and a slurry which is free abrasive. The present invention relates to a method for manufacturing a magnetic disk which is improved in durability and has low glide height characteristics.

[0002]

2. Description of the Related Art Generally, a magnetic disk has a non-magnetic surface made of an aluminum alloy or the like hardened by an alumite treatment or a nickel-phosphorus electroless plating treatment, and the surface thereof is ground to a predetermined roughness, and then a magnetic layer is formed. It is manufactured by successively forming an underlayer for improving the characteristics of 1, a magnetic layer and a protective layer, and further providing a lubricating layer.

The magnetic disk thus manufactured is mounted on a fixed magnetic disk device used as an external storage device, and information is recorded while the magnetic head is levitating on the magnetic disk which is rotating at high speed. Alternatively, reproduction is performed. Therefore, it is required that the surface of the magnetic disk does not have a protrusion having a height that hinders stable running of the magnetic head, that is, good glide characteristics.
In the advanced information society of recent years, a magnetic disk having a higher recording density is required, and in order to achieve this, it is necessary to reduce the distance between the magnetic layer of the magnetic disk and the magnetic head, that is, the magnetic disk. Smoothing of the surface is desired.

On the other hand, in the magnetic disk device, in order to stably maintain a minute gap between the head and the magnetic disk, the magnetic head comes into contact with the magnetic disk and stops when the magnetic disk is stopped. A so-called contact start / stop (CSS) method in which the vehicle slides on the surface and runs floating is adopted. This C.
S. S. The method requires durability that can maintain a sliding friction coefficient between the magnetic disk and the magnetic head, which is generated at the time of starting and stopping the magnetic disk device, to be sufficiently small.

For this reason, microtexturing is formed on the non-magnetic surface layer on the substrate, and texturing is performed to reduce the friction coefficient between the magnetic disk and the magnetic head. As such a texturing method, generally, a tape / tape texturing method in which a magnetic disk is ground in multiple stages using a polishing tape, or after performing polishing with a polishing tape in the first stage, In the second stage, a tape / diamond slurry texturing method is used in which grinding is performed using a slurry in which diamond powder is dispersed.

[0006]

However, in such a conventional method of manufacturing a magnetic disk by texturing, the distance between the magnetic layer of the magnetic disk and the magnetic head is made as small as possible in order to achieve high density. Due to this restriction, protrusions on the surface of the magnetic disk have been removed, and texturing processing for a smoother surface condition has been made. However, it is difficult to obtain stable durability with such a magnetic disk having a smooth surface, and as a result, good glide characteristics and durability characteristics are sufficiently obtained for a low flying height head. It has been difficult to produce a satisfactory magnetic disk.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, the slurry type free abrasive grains have a Knoop hardness of 1000 to 6000.
It was found that a magnetic disk having good low glide characteristics and sufficient durability can be manufactured by using a grinding abrasive grain in the range of, and the present invention has been completed. It was

The present invention will be described below with reference to the drawings.

FIG. 1 shows a part of a sectional view of an apparatus in which the present invention can be implemented. Reference numeral 1 denotes a magnetic disk substrate to which the texturing process of the present invention is applied. Examples of the non-magnetic substrate in the present invention include aluminum, aluminum alloys,
Ceramics, glass, or the like can be used, and an alumite treatment layer or a surface coating layer of nickel-phosphorus alloy or the like may be further provided on the surface thereof.

In the case of grinding with fixed abrasives, the polishing tape 2 is used while discharging the grinding liquid from the discharge port 3 of the grinding liquid, and in the case of grinding with free abrasives, the buff tape. Grinding is performed by using 2 ', while discharging the slurry in which the abrasive grains are mixed and dispersed in the grinding liquid from the slurry discharge port 3'. Reference numeral 4 denotes a pressure rubber roller for pressing the polishing tape or the buff tape into pressure contact with the substrate surface.

In the actual manufacture of the magnetic disk substrate, two texturing units may be used to continuously grind with fixed abrasive grains and grind with loose abrasive grains.

In the method of manufacturing a magnetic disk substrate according to the present invention, the apparatus shown in FIG. 1 is used, and a polishing tape 2 which is a fixed abrasive having abrasive particles adhered to the tape is used. Discharge into the gap between the substrate and the polishing tape,
Grinding is performed while pressing the polishing tape on the disk substrate by the pressing rubber roller 4. The average grain size of the abrasive grains of the polishing tape at this time may be, for example, 0.5 to 9.0 μm, and particularly preferably, the average grain size of the abrasive grains is 1.0 to 4. The thickness is 0 μm. Further, as the material of the abrasive grains, one or more kinds selected from alumina, silicon carbide, diamond and the like may be used. The grinding with the fixed abrasive may be performed once or more, but preferably Ra in the radial direction at a position of 21 mm from the center of the disk substrate.
Is adjusted to fall within the range of 90 to 120 angstroms, and particularly preferably adjusted to fall within the range of 90 to 100 angstroms.

Subsequently, the abrasive grains are mixed with a grinding fluid and stirred,
While the slurry liquid, which is free abrasive grains uniformly dispersed, is discharged from the discharge port 3'between the magnetic disk substrate and the buff tape 2 ', the pressure rubber roller 4 presses the disk substrate to perform grinding.

The abrasive grains used in the slurry here are:
Knoop hardness is in the range of 1000 to 6000, preferably
It is in the range of 2000 to 5000. The Knoop hardness referred to in the present invention means that a pyramidal diamond indenter is brought into contact with the surface of the object to be measured, and after light weight is applied,
It is determined by measuring the size of the diamond-shaped depressions formed on the surface of the object to be measured.

As such abrasive grains, for example, boron nitride, silicon carbide, aluminum oxide and the like used as industrial materials are suitable.

As the grinding liquid, a water-soluble grinding liquid containing a surfactant or the like or a non-water-soluble grinding liquid is used, and the concentration of the grinding abrasive particles may be dispersed at 0.05 to 100 g / l.
Particularly, 0.1 to 10 g / l is preferable.

The discharge amount of the slurry liquid is 1.0 to 200 ml
It should be within the range of 10 / min, but especially 10 to 80 ml
/ Min is preferable.

As the buff tape, a non-woven fabric capable of supporting abrasive grains or a flexible material such as flocked fabric may be used. The grinding with the free abrasive grains may be performed once or more, but it is preferable that the Ra in the radial direction at a position of 21 mm from the center of the disk substrate be within a range of 50 to 85 angstroms, particularly preferably 60. Adjust to within ~ 75 Å.

After that, a magnetic disk may be manufactured by laminating an underlayer, a magnetic recording layer, a protective layer and the like on a textured non-magnetic substrate by a sputtering method or the like. A liquid lubricating layer can be further applied, if necessary.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 A disk substrate made of an aluminum alloy and having a diameter of 3.5 inches was subjected to electroless plating with a nickel-phosphorus alloy, and subsequently, the centerline average roughness Ra of this nickel-phosphorus surface layer was 20 to 25. It was mirror-polished to have an angstrom.

Next, a polishing tape 2 (manufactured by Mypox Co., Ltd., manufactured by Mypox Co., Ltd.) was prepared by adhering alumina abrasive grains having an average particle size of 3 μm to the tape on the surface layer of nickel-phosphorus alloy of this substrate using the apparatus shown in FIG. Name "TOY- # 4000"), and the tape is attached to the disk substrate 1 by a pressing rubber roller 4.
Grinding fluid diluted with pure water to 5% by volume (manufactured by Mypox, trade name "SuperLube No. 65Y")
While the tape was being fed while being dripped from the discharge port 3, the disk was rotated and ground. By the grinding process using the fixed abrasive grains, Ra in the radial direction at a position 21 mm from the center of the disk substrate was adjusted to 90 to 100 angstroms.

Then, subsequently, on the same surface of the disk substrate, the Knoop hardness is 3100 to 340 with an average particle diameter of 1 μm.
Grinding liquid made by diluting silicon carbide of 0 to 5% by volume with pure water (manufactured by Mypox, trade name "SuperLube No. 65
Y ”), a slurry of free abrasive grains stirred and dispersed at a concentration of 0.4 g / l at a discharge rate of 20 ml / min.
Buff tape 2 '(Chiyoda Co., Ltd., trade name "SPD 2501-EG") made of woven blanket while dripping from
Grinding is performed in the same manner as in the case of the polishing tape, and Ra in the radial direction at a position of 21 mm from the center of the disk substrate is used.
Was adjusted to 60-75 angstroms.

The hardness of the abrasive grains used here is determined based on the Knoop hardness measurement method. A pyramidal diamond indenter is brought into contact with the surface of the object to be measured, and a light weight is applied to the surface of the object to be measured. It was determined by measuring the size of the diamond-shaped depressions formed in the. The length of the diagonal of the indentation is 7.11: 1, and the length in the longitudinal direction is L.
When assuming (m), the hardness when the weight P (g) is applied is obtained by the following calculation formula.

Knoop hardness = 14.22 × P / L A Cr underlayer 2 was formed on this disk substrate by sputtering.
000 Å, Co-Cr-Ta (Cr: 1
2 atomic%, Ta: 2 atomic%, balance Co) magnetic layer 500
An angstrom and a C protective layer of 200 angstrom were sequentially laminated, and a perfluoropolyether-based liquid lubricant was applied to a thickness of 20 angstrom by a dipping method to manufacture a magnetic disk.

Example 2 21 mm from the center of the disk substrate by grinding with fixed abrasives using a polishing tape having an average particle size of 3 μm as in Example 1.
After adjusting the radial direction Ra at 90 to 100 angstroms, the Knoop hardness is 4400 to 4800 with an average particle size of 1 μm on the same surface of the disk substrate.
Grinding is performed by using a slurry that is free abrasive grains in which boron nitride is dispersed by stirring.
The Ra in the radial direction at the position of mm was adjusted to 60 to 75 angstroms, and an underlayer, a magnetic layer, a protective layer and a lubricant layer were formed by the same method as in Example 1 to prepare a magnetic disk.

Comparative Example 1 In the same manner as in Example 1, 21 m from the center of the disk substrate was obtained by grinding with fixed abrasive grains using a polishing tape having an average particle size of 3 μm.
After adjusting the radial direction Ra at the m position to 90 to 100 angstroms, a polishing tape which is a fixed abrasive having an average particle diameter of 2 μm (manufactured by Mypox, trade name “FOY- # 60”).
00 ") is similarly used to grind with fixed abrasive grains to adjust Ra in the radial direction at a position of 21 mm from the center of the disk substrate to 60 to 75 angstroms, and the underlayer is formed in the same manner as in Example 1. , Magnetic layer, protective layer,
A lubricant layer was formed to produce a magnetic disk.

Comparative Example 2 Grinding with fixed abrasives using a polishing tape having an average particle size of 3 μm, as in Example 1, was performed from the center of the disk substrate to 2
After adjusting Ra in the radial direction at a position of 1 mm to 90 to 100 angstroms, grinding is performed using a slurry that is free abrasive grains in which diamond powder having an average particle size of 1 μm and a Knoop hardness of 6500 to 8000 is stirred and dispersed. Then, Ra in the radial direction at a position of 21 mm from the center of the disk substrate was adjusted to 60 to 75 angstroms, and the underlayer, magnetic layer, protective layer, and
A lubricant layer was formed to produce a magnetic disk.

The surface roughness, the number of glide hits at a glide height of 0.075 μm, and the continuous sliding friction characteristics were examined for the magnetic disks having various surface shapes prepared by the above-mentioned Examples and Comparative Examples.

The surface roughness was measured with a stylus radius of 0.5 μm by a diamond stylus method using a fine shape measuring instrument model ET-30HK manufactured by Kosaka Laboratory Ltd.

The glide hit characteristic was measured by an RX2000 magnetic disk tester manufactured by Hitachi Electronics Engineering Co., Ltd., using a glide head equipped with a piezo element.
One side was measured within a radius of 20 to 44 mm from the center of the magnetic disk substrate when traveling at a flying height of 0.075 μm.

The continuous sliding friction characteristic was measured by using a wear tester manufactured by Kubota Comps Co., Ltd., with a vertical load of 9.0 g, a position of 21 mm from the center of the magnetic disk substrate, and a rotational speed of 100 rp with the magnetic head in contact with the disk surface.
It was rotated at m and the dynamic friction coefficient was measured at 1 rpm after conducting a continuous sliding test for 3 hours.

Table 1 shows the surface roughness, the number of glide hits, and the coefficient of dynamic friction.

[0034]

[Table 1] As shown in Table 1, Ra in the radial direction is adjusted within the range of 60 to 75 angstroms for both the discs of Examples and Comparative Examples. Comparing the numbers of glide hits with each other, the number of hits was 0 in both Examples 1 and 2, showing excellent glide characteristics. On the other hand, in the result of the comparative example, the comparative example 1 by the tape / tape method
The number of hits is about 90 to 130, and tape /
The result of Comparative Example 2 using the diamond slurry method also has a very large number of hits of about 70 to 90, which is a serious problem in practical use.

On the other hand, the friction coefficient after the continuous sliding test for 3 hours is 0.29 in both Examples 1 and 2 and Comparative Examples 1 and 2.
It is within the range of 0.41, which is a practically satisfactory value,
It is shown that good durability is obtained.

[0036]

As described above, according to the present invention, a non-magnetic substrate is ground with a fixed-abrasive-type polishing tape, and then the abrasive grains having a Knoop hardness in the range of 1000 to 6000 are used as a grinding liquid. By performing a texturing process that uses a slurry that is free abrasive grains mixed and dispersed in the magnetic disk, it is possible to reduce the flying height of the magnetic head, and to obtain a magnetic disk with good glide characteristics and durability. It can be manufactured.

[Brief description of drawings]

FIG. 1 shows a cross-sectional view of a portion of an apparatus in which the present invention may be implemented.

[Explanation of symbols]

 1 ... Magnetic disk substrate 2 ... Polishing tape 2 '... Buff tape 3 ... Grinding liquid discharge port 3' ... Slurry discharge port 4 ... Pressurizing rubber roller

Claims (1)

[Claims] 1. A method of manufacturing a magnetic disk comprising a non-magnetic substrate, a surface of which is subjected to texturing, and a magnetic layer of which is further laminated. With tape
Knoop hardness of 1000 after grinding more than once
To 6000, grinding slurry is mixed and stirred in a grinding liquid, and a slurry is dripped into a gap between the buff tape and the magnetic disk, and a grinding process is further performed once or more. ..