JPH0817054A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To remove abnormal protrusions on the surface of a magnetic recording medium. CONSTITUTION:A magnetic layer is formed on a carbon substrate to produce a magnetic recording medium. This magnetic recording medium and an abrasive tape are brought into contact with each other under 0.1-5kg/cm<2> pressure and the magnetic recording medium and/or the abrasive tape is allowed to run at 10-200m/min relative speed.

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 recording medium.

[0002]

BACKGROUND OF THE INVENTION In a magnetic disk system, in consideration of reproduction output, it is advantageous that the distance (flying height) between a magnetic recording medium and a magnetic head is small, that is, the spacing loss is small. In other words, it is desirable that the magnetic disk surface be smooth. Therefore, the surface of the magnetic disk is finished with a polishing tape after forming a protective layer or applying a lubricant.

For example, in the manufacturing process of a magnetic disk medium, after the surface of the magnetic disk medium is processed by using a polishing tape, the polishing tape is used to effectively remove only the fine projections existing on the surface. Peripheral speed 250m / mi
Proposed is a method for producing a magnetic disk medium in which the tape processing pressure is not less than n and not more than 50 g / mm ^2.
No. 134, Japanese Patent Publication No. 2-10486).

By the way, in recent years, carbon, particularly glassy carbon, has been proposed as a substrate material for magnetic disks instead of Al alloy or glass (Japanese Patent Publication No. 63-46004, Kobe Steel Technical Report, Vo139, No4, pp35 to 3).
8, 1989). That is, since this substrate has excellent features such as lightness, smoothness, heat resistance, and conductivity, it is attracting attention as a substrate that can be used for high-density recording.

However, when the technique proposed in Japanese Patent Laid-Open No. 59-148134 is applied to such a magnetic disk made of a carbon substrate, the removal of the fine protrusions has not been effectively performed.

[0006]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a technique capable of removing abnormal protrusions on the surface of a magnetic recording medium. An object of the present invention is a method for producing a magnetic recording medium in which a magnetic layer is provided on a carbon substrate, and the magnetic recording medium provided with the magnetic layer and a polishing tape are used in an amount of 0.1 to 5 kg.
Abutting with a force of / cm ² and a relative speed of 10 to 200 m / m
This is achieved by a method for manufacturing a magnetic recording medium, which comprises running a magnetic recording medium and / or a polishing tape in the in.

A polishing tape is brought into contact with the surface of the present invention with a force of 0.1 to 5 kg / cm ² , and the relative speed is 1
Before the step of running the magnetic recording medium and / or the polishing tape at 0 to 200 m / min to remove the abnormal protrusions existing on the surface, the magnetic recording medium has its basic structure already configured. For example, a step of forming a magnetic layer on a carbon substrate by dry plating such as vapor deposition or sputtering, a dry plating means such as vapor deposition or sputtering on the magnetic layer, or a protective layer by dipping or spin coating. A magnetic recording medium is configured through the steps of providing the magnetic recording medium, and the magnetic recording medium is subjected to an operation of removing abnormal protrusions existing on the surface. Further, before providing the magnetic layer, a magnetic recording medium is manufactured through a step of providing an underlayer on a carbon substrate by dry plating means such as vapor deposition or sputtering means.

Incidentally, it is preferable to employ dry plating means for film formation. That is, the dry plating means is more likely to obtain a high-quality magnetic film than the wet plating means. Further, the composition of the magnetic film can be easily changed, and the design of the magnetic film can be easily changed. A lubricant is usually applied to the surface of the magnetic recording medium. This lubricant is usually only provided by applying a lubricant solution, and the surface profile (projections) does not change before and after the lubricant is applied. Work to remove the protrusion is performed. Although the work of removing the abnormal protrusion may be performed after applying the lubricant, in view of the fact that the lubricant is wiped off by this work, the lubricant must be applied again. Absent. Therefore, normally, the work of removing the abnormal protrusion is performed before the lubricant is provided.

Then, through the above steps, the abnormal protrusions left on the surface of the magnetic recording medium are removed. As a result, the flying height of the magnetic head can be reduced and the spacing loss can be reduced, which is preferable in terms of reproduction output. In the present invention, the conventional technology is used as it is for the configuration of the magnetic layer on the substrate. That is, a base layer (base film) provided on the substrate,
The conventional techniques can be used as they are for the structures of the magnetic layer (magnetic film), the protective layer (protective film), the lubricating layer (lubricating film), and the like. For example, the techniques described in JP-A-5-18952, JP-A-5-137822, JP-A-5-217169 and JP-A-5-289496 can be used.

The magnetic recording medium of the present invention has a substrate made of carbon. That is, even if the present invention is applied to a magnetic recording medium other than the carbon substrate, the abnormal protrusion cannot be removed. The substrate of this magnetic recording medium of the present invention is composed of carbon, and particularly preferably glassy carbon. Such a carbon material is more elastic than the Al alloy substrate and has a linear expansion coefficient of 1/7.
It has the characteristic that the thermal conductivity is 1/25. Since there is a large difference in the grindability of the protrusions,
It is presumed that the result was different from that of the magnetic recording medium using the 1-alloy substrate.

Such a carbon material is a carbon material obtained by carbonizing a thermosetting resin, a carbon material obtained by carbonizing a resin modified to be thermoset by copolymerization, cocondensation, etc., a cured or carbon material. There are carbon materials and the like obtained by significantly hindering crystallization by a chemical treatment in the process of crystallization. Then, such a carbon substrate is subjected to a predetermined texture treatment before film formation. For example, texture processing is performed by means such as tape polishing and electrolytic polishing. Then, a substrate having Ra of about 10 to 300Å and Rp / Ra (Ra = center line average roughness, Rp = center line height) of about 2 to 15 is obtained.

After the base film, the magnetic film, the protective film, etc. are provided on this substrate, the work of removing the abnormal projection of the present invention is performed. At this time, a polishing tape is used. The polishing tape used in the present invention includes Al ₂ O ₃ and Si.
C, ZrO ₂ , diamond, cerium oxide, SiO ₂
Particle size of 0.1 to 10 μm (preferably 0.2 to 2 μm)
The abrasive grain m) provided on a flexible support (base film) with an organic binder is used.

Then, such an abrasive tape is magnetically recorded.
0.1 to 5 kg / cm on the surface of the medium ²(Preferably 0.
5-2 kg / cm²) Force is applied, and relative at the outermost circumference
Speed (relative speed at the fastest position) is 10-200m /
Sliding at min (preferably 30 to 100 m / min)
By doing so, the abnormal protrusion is removed. The pressure is
0.1 kg / cm²If less than, the removal property of abnormal protrusions is
On the contrary, 5 kg / cm²If it exceeds the range, processing scratches are likely to occur
Cause an error. And the relative speed is 10m /
If it is less than min, the productivity is low, and if it exceeds 200 m / min
Variation will increase and the abnormal protrusions on the entire surface will be uniform.
Hard to remove.

The present invention will be described below with reference to specific examples.

[0015]

[Example] Texture processing is performed and Ra is about 21 ±.
1.7Å, Rp about 285 ± 86Å, plate thickness 0.635m
A glassy carbon substrate having a diameter of 1.8 inches and a diameter of 1.8 inches was prepared. The physical properties of this glassy carbon are as follows. Density 1.8 g / cm ³ , Young's modulus 35 GPa,
Thermal conductivity 3.5 to 3.8 W / m ° C, linear expansion coefficient 3.5
× 10 ^-6 / ° C.

For this glassy carbon substrate, A
D under the condition of r gas pressure of 2 mTorr and substrate temperature of 200 ° C
Using a C magnetron sputter device, deposit the underlying Cr film
The thickness is set to 0 nm, and then a Co-Cr-Pt magnetic film is formed to 50 nm.
nm thickness was provided. Then, a carbon protective film having a thickness of 15 nm was formed on the Co—Cr—Pt magnetic film. A burnisher (Hitachi DECO SB3251-05) was used for the magnetic disk obtained as described above, and a polishing tape (WA10000 SFO manufactured by Mypox) was used.
Y-B, WA8000 SFO Y-B) and Table-1
Since the work was performed under the conditions shown in, the results are also described.

Table-1 Relative speed Surface roughness after working pressure Glaiter error (m / min) (kg / cm ² ) Ra (Å) Rp (Å) Ito test characteristics Example 1 25 0.5 20 ± 1.6 210 ± 20 ○ ○ Example 2 50 0.75 20 ± 1.8 220 ± 20 ○ ○ Example 3 100 2.0 20 ± 1.5 225 ± 22 ○ ○ Example 4 150 4.0 18 ± 1.6 231 ± 36 ○ ○ Example 5 50 0.5 19 ± 1.8 180 ± 18 ○ ○ Example 6 70 0.75 21 ± 1.6 195 ± 22 ○ ○ Example 7 150 1.0 21 ± 2.2 220 ± 27 ○ ○ Comparative Example 1 50 10.0 18 ± 1.6 160 ± 18 ○ × Comparative Example 2 300 0.5 21 ± 2.5 275 ± 80 × ○ * Examples 1 to 4 and Comparative Examples 1 and 2 are WA 10000SFOY
-B polishing tape is used * Examples 5 to 7 are WA 8000 SF
OY-B polishing tape used * Relative speed is the relative speed at the sliding contact part between the rotating magnetic disk (outermost position) and the running polishing tape * Processing pressure is the pressure when the polishing tape is pressed against the magnetic disk (It was calculated by dividing the total pressure by the footprint area (area in which the medium was stopped, the tape was run, and the scratched area).) * The Ra of the magnetic disk surface before processing was 21 ± 1.7.
Å, Rp is 285 ± 86 Å * Processing time is set so that the total number of rotations of the magnetic disk is 50.

* Glitter height characteristic is Proquip
This was carried out using a MG150T apparatus manufactured by Co., Ltd. and a 50% slider head. ∘ indicates 80% or more of those passing a flying height of 1.2μ inches without collision × indicates 50% or less of those passing a flying height of 1.2μ inches without collision * Error characteristics are Proquip Recording density of 4 using 70% slider head with MG150T device
It was evaluated under the condition of 5 to 50 KFCZ.

A circle indicates that the number of missing errors of less than 16 bits is 15 or less and a circle indicates that the number of missing errors is over 45 / side. As can be seen from this, in the present embodiment, the abnormal protrusions on the surface are effectively removed, and it is understood that an error hardly occurs.

That is, since only the minute protrusions on the surface of the magnetic disk are removed, the surface property is improved, the spacing loss can be reduced as much, and it is also preferable from the viewpoint of reproduction output.

[0021]

According to the present invention, abnormal projections on the surface of the magnetic recording medium can be effectively removed, errors are unlikely to occur, and reproduction output is high.

Claims (3)

[Claims] 1. A method for manufacturing a magnetic recording medium comprising a magnetic layer provided on a carbon substrate, wherein the magnetic recording medium provided with the magnetic layer and a polishing tape are 0.1 to 5 kg /.
Contact with a force of cm ² and a relative speed of 10 to 200 m / mi
A method of manufacturing a magnetic recording medium, comprising: running a magnetic recording medium and / or a polishing tape at n. 2. A step of providing a magnetic layer on a carbon substrate by dry plating means, a step of providing a protective layer on the magnetic layer by dry plating means, and after the protective layer is provided,
The polishing tape is brought into contact with the surface with a force of 0.1 to 5 kg / cm ² , and the magnetic recording medium and / or the polishing tape is run at a relative speed of 10 to 200 m / min to remove abnormal protrusions existing on the surface. The method of manufacturing a magnetic recording medium according to claim 1, further comprising: 3. The method for producing a magnetic recording medium according to claim 2, further comprising the step of providing an underlayer on the carbon substrate by dry plating before the magnetic layer is provided.