JPH04195715A - Perpendicular magnetic recording medium - Google Patents

Abstract

PURPOSE:To eliminate a curl and obtain a sufficiently high playback output by a method wherein a metal thin film having a Young's modulus not less than 25.4X10<5> (kg.cm<-2>) is formed on the rear surface of a polymer film which is opposite to the magnetic recording surface. CONSTITUTION:A metal thin film 3 having a Young's modulus not less than 2.5X10<5> (kg.cm<-2>) is formed on the rear surface of a polymer film 2 which is opposite to the magnetic recording surface. As the film 3 has a high Young's modulus, a curl can be controlled with a thickness not larger than a half of the thickness of a conventional correction film. With this constitution, the curl can be eliminated while the low rigidity of the medium as a whole is maintained, so that an optimum application to a head can be obtained and the playback output of a perpendicular magnetic recording medium can be increased.

Description

Detailed Description of the Invention A3.Objective of the Invention [Field of Industrial Application] The present invention relates to perpendicular magnetic recording using a continuous magnetic thin film for perpendicular magnetic recording in which a magnetic recording layer is formed on a polymer film. It's about the medium.

[Conventional technology]

In recent years, with the demand for higher density magnetic recording, there has been active research into so-called continuous magnetic media in which the magnetic recording layer is formed only of magnetic materials.

Since the magnetic recording layer of continuous magnetic media manufactured by vacuum evaporation, sputtering, or plating is a thin film, longitudinal recording is a hot topic, and a dramatic increase in recording density is expected, especially in perpendicular magnetic recording. Research and development is underway to commercialize various products such as magnetic tape and magnetic disks.

A CoCr alloy film or the like is used as the magnetic recording layer of a perpendicular magnetic recording medium. Since perpendicular magnetic recording media can record and reproduce data at high densities even when using a ring head, they are compatible with currently commercially available systems, and are being considered for application as an extension of commercially available systems.

A conventional perpendicular magnetic recording medium is shown in FIG. A thin film for perpendicular magnetic recording such as a CoCr alloy is formed as a magnetic recording layer to a thickness of 0.2 to 0.3 μm on a heat-resistant polymer film 2 by sputtering or the like. Further, the same material is deposited on the back surface of the polymer film opposite to the recording/reproducing surface to form a film of 0.2 μm to 0.3 μm to form a back surface correction layer 3 for preventing curling of the medium.

- Measurement of curl is to measure the deviation of the edge of the medium on the extension of the plane of the central metal hub attachment part, as shown in FIG. In the case of magnetic recording media with 2" disks, the standard is
As shown in the figure, the curl is 0mm inside 2+u from the end.
0.4 for the plane! It is below I11.

However, the magnetic recording medium produced in this way has a problem of low output during recording and reproduction when a commercially available driver is used. The output was reduced to about one-half, which was a practical problem. (See Figure 5) [Problems to be Solved by the Invention] The present invention provides a perpendicular magnetic recording medium in which a thin film for perpendicular magnetic recording is formed as a magnetic recording layer, which is less likely to curl and which can be reproduced at a sufficiently high level using a commercially available driver. The present invention aims to provide a perpendicular magnetic recording medium that can provide high output.

1. Structure of the Invention [Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventor has developed a method using Young's modulus as a curl correction film provided on the back surface of the medium, as shown in FIG. We would like to show that by forming a metal thin film with a thickness of 25.4 x 105 [kg-cm-2] or more, it is possible to improve the reproduction output with almost no curling. That is, the present invention provides a perpendicular magnetic recording medium in which a magnetic recording layer of a magnetic thin film is formed on a polymer film by vapor deposition, sputtering, ion plating, or the like. This is a perpendicular magnetic recording medium characterized by forming a metal thin film having a Young's modulus of 25.4×105 [kg-cm-2] or more on the back surface.

[Effect]

Spacing loss is one of the causes of reducing the reproduction output of magnetic recording media. It is desirable that the head and medium contact each other during recording and reproduction, as shown in Figure 4(a), so that the curvatures of the head and medium match and the head and medium are in close contact. In the case of a perpendicular recording medium, the thickness of the entire medium including the base polymer film, magnetic recording layer, and back correction layer is thick and rigid, so the contact between the medium and the head is as shown in Figure 4 (b). As a result, the spacing becomes large and the adhesion between the head and the medium becomes poor, resulting in a reduction in reproduction output. If the back correction layer on the back side of the polymer film is made thinner in order to lower the rigidity, curling cannot be controlled and performance that meets the standards cannot be obtained.

Therefore, the present inventor used materials with high Young's modulus such as Ir, Os, Cr, Bi, W, Ru, etc. for back surface curl correction.
Films of No, Be, Rh, etc. were formed. Since these films have a high Young's modulus, curl can be controlled with a film thickness less than half that of conventional correction films.

The stiffness of the media, which causes spacing loss, affects the overall thickness of the media. However, by using the back surface correction film of the present invention, the curl can be removed while the rigidity of the entire medium remains low. Therefore, it has been found that the reproduction output of a perpendicular magnetic recording medium can be increased by obtaining the optimum contact condition with the head.

〔Example〕

Examples according to the present invention and comparative examples will be described in detail below with reference to the drawings. The embodiment of the present invention is the first embodiment of the present invention.
As shown in the figure, a magnetic recording layer 1 for perpendicular magnetic recording is formed on a polymer film 2, and a protective film 4 is formed on the surface thereof. A back surface correction layer 3 is formed on the back surface of the polymer film 2 in order to correct curls. The conditions for producing media for Comparative Examples and Examples are shown below.

(Comparative example) A 0.3 μm thick layer of CoC, which is a magnetic recording layer 1 for perpendicular magnetic recording, was formed on a polymer film 2 of a polyimide film with a thickness of 30 μm as a base by an RF magnetron method.
Form a r (Cr: 17 wt$, Co: bal) film,
A protective film 4 of C was formed thereon to a thickness of 20 angstroms. A CoCr film was similarly formed on the back surface of the polymer film 2 as a back surface correction layer 3. The sputtering pressure at this time was 0.1 [Pa], and the RF power density was 2.74
[w/Cm2], the distance between the target and the substrate is 90!
l! It was set as l. A can device was used for sputtering.

(Example 1) In a comparative example, an Ir film of 0.1 μm was formed as a back correction layer on the back side of a polymer film. (Example 2) In a comparative example, an Os film was formed as a back correction layer on the back side of a polymer film. (Example 3) In a comparative example, a Cr film of 0.1 μm was formed as a back correction layer on the back side of a polymer film (Example 4) In a comparative example, a Cr film of 0.1 μm was formed on the back side of a polymer film as a back correction layer. A 0.1 μm Bi film was formed as a correction layer (Example 5) In a comparative example, a 0.1 μm W film was formed as a back correction layer on the back side of a polymer film (Example 6) In a comparative example, a 0.1 μm layer of Ru film was formed as a back correction layer on the back surface of the polymer film (Example 8). In the example, a 0.1 μm thick Be film was formed as a back correction layer on the back side of the polymer film (Example 9). In the comparative example, a 0.1 μm thick Rh film was formed on the back side of the polymer film as a back correction layer. A 2-inch disk was punched out from the medium material prepared under the conditions of the comparative example and Examples 1 to 9, and a 2-inch floppy disk was prepared, and the electromagnetic conversion characteristics were evaluated.

FUJIX-HR5 was used as the recording/playback system at this time.
000 was used.

FIG. 5 shows the recording frequency characteristics of a commercially available medium using metal magnetic powder, a comparative example, and Example 1.

FIG. 6 shows the output ratio at 10 MHz in Examples 1 to 9 with respect to commercially available media. It can be seen that all of Examples 1 to 9 have reproduction outputs that are more than twice that of commercially available media using metal magnetic powder.

Table 1 shows the Young's modulus of the metal thin film used for the back surface correction layer of this example. From the results in Table 1, Young's modulus is 25.4
A medium with a high reproduction output has been obtained by using a metal film with a thickness of 105 kg-cm-2 or more as the backside correction layer.

Table 1 In this example, the backside correction layer contains Ir, Os, Cr,
Bi, W.

Although films of Ru, Mo, Be, Rh, etc. were used, films with a Young's modulus of 25.4×105 [kg-C-12] or more may be made of a single metal or an alloy thereof, and are not affected by the material. Further, in this embodiment, a 2'' medium was described, but a 3.5'' medium or tape may also be used, and the effect was obtained regardless of the shape.

C1. Effects of the Invention [Effects of the Invention] As described above, according to the present invention, a perpendicular magnetic recording medium with significantly increased reproduction output and no curling can be provided.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating the configuration of a perpendicular magnetic recording medium according to the present invention. FIG. 2 is an explanatory diagram illustrating the curl measurement method for a 2" disk. FIG. 3 is an explanatory diagram illustrating the structure of a conventional perpendicular magnetic recording medium. FIG. 4 is an explanatory diagram illustrating the contact between the head and the medium. Fig. 4(a) shows a state in which the head and medium are in close contact, and Fig. 4(b) shows a state in which the spacing is large and the adhesion is poor. Fig. 5 shows a commercially available magnetic recording medium and a conventional magnetic recording medium. perpendicular magnetic recording medium,
1 and 2 show the recording frequency characteristics of the reproduction output of the perpendicular magnetic recording medium according to the present invention. FIG. 6 is a diagram showing the reproduction output ratio of a commercially available magnetic recording medium and a perpendicular magnetic recording medium of each embodiment according to the present invention. 1... Magnetic recording layer, 2... Polymer film, 3...
Back correction layer, 4...protective film, 5...medium, 6...head, 7...metal hub. Patent applicant Tokin Co., Ltd. Figure 7 Figure 2 Figure 3 Figure 4 (Q) (b) Figure 5 Figure 6 Storehouse

Claims (1)

[Claims] 1. In a perpendicular magnetic recording medium in which a magnetic recording layer of a magnetic thin film is formed on a polymer film by vapor deposition, sputtering, ion plating, etc., a .4×10^5[k
A perpendicular magnetic recording medium characterized by forming a metal thin film having a Young's modulus of 1 g·cm^-^2] or more.