JPH04238116A - Magnetic disk - Google Patents

Abstract

PURPOSE:To improve durability while well assuring electromagnetic conversion characteristics by imparting texture traces of prescribed angles to the surface of a rigid substrate. CONSTITUTION:This disk is constituted by providing a magnetic layer 4 on the rigid substrate and imparting the texture traces having 5 to 30 deg. angle circumferentially on the surface of the substrate. For example, the disk is obtd. by forming the above-mentioned texture traces on the surface of an Ni-P plating film 2 formed on an aluminum substrate 1, then successively depositing an underlying layer 3 consisting of a Cr film, etc., a layer 4 consisting of a Co-Ni-C film, etc., a protective layer 5, and a lubricant layer 6 thereon. The surface of the layer 4 has fine rugged shapes if the disk is formed in such a manner and, therefore, the contact area with a magnetic head decreases and the friction force with the disk decreases.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk used as a storage medium in a hard disk drive.

0002

[Prior Art] For example, disk-shaped magnetic disks that can be randomly accessed are widely used as storage media for hard disk devices such as computers. , magnetic disks (hard disks) whose substrates are made of hard materials such as aluminum are used.

In such magnetic disks, a non-magnetic underlayer having a certain degree of hardness is usually provided between the magnetic layer (recording layer) and the substrate in order to withstand shocks caused by contact with the magnetic head. It is formed. This nonmagnetic underlayer can increase the hardness of the substrate, and can also improve the adhesion between the substrate and the magnetic layer to prevent problems such as the magnetic layer falling off.

In such a structure, the properties of the lower layer greatly influence the properties of the upper layer, so severe physical, chemical, and mechanical conditions are imposed on each of these functional films. Particularly in recent years, the flying height of magnetic heads has tended to be reduced (lower flying height) for the purpose of higher density recording, and with this, serious problems such as signal errors, dropouts, and even head crashes have become a problem. It has become. In order to avoid these problems, it is extremely important to improve the uniformity, adhesion, and smoothness of each functional film mentioned above.
Therefore, it is required that the surface of the substrate on which these are formed be extremely smooth.

However, if the surface of the substrate is too smooth, there is a risk that the magnetic head and the disk will stick together, resulting in deterioration of durability. Therefore, before forming the magnetic layer, the surface of the substrate is subjected to a texture treatment (a treatment for finely roughening the substrate surface). As a result, fine irregularities imparting shape magnetic anisotropy are formed on the surface of the substrate, and the magnetic layer formed on the substrate is made irregular accordingly.

[0006]

In the texturing process for roughening the surface of a substrate, the shape of the surface of the textured substrate greatly influences its squareness, durability, and the like. Therefore, it is important to find a surface shape that improves durability while ensuring good electromagnetic conversion characteristics.

[0007] For example, until now it has generally been said that the above-mentioned texture treatment is performed only in the circumferential direction, but it is difficult to say that this is sufficient to achieve both electromagnetic conversion characteristics and durability. The present invention was proposed in view of the above circumstances, and an object of the present invention is to provide a magnetic disk that has excellent durability while ensuring good electromagnetic conversion characteristics.

[0008]

[Means for Solving the Problems] As a result of intensive research in order to achieve the above-mentioned object, the present inventors have provided texture marks in the circumferential direction of a magnetic disk, and have provided texture marks in a certain manner in the circumferential direction. The inventors discovered that the contact area between the magnetic head and the surface of the medium can be reduced by forming texture marks in an angular direction, leading to the completion of the present invention.

That is, the present invention provides a magnetic disk in which a magnetic layer is provided on a rigid substrate, in which texture marks forming an angle of 5 to 30 degrees with respect to the circumferential direction are provided on the surface of the rigid substrate. It is characterized by this.

0010

[Operation] By forming a magnetic layer on a rigid substrate on which texture marks are formed on the surface at an angle of 5 to 30 degrees with respect to the circumferential direction, the thickness of the magnetic layer is adjusted according to the surface shape of the rigid substrate. The surface becomes uneven. Now, if we consider the case where a magnetic head is brought into contact with a magnetic disk that has texture marks applied only in the circumferential direction, the magnetic disk and magnetic head will be in a line contact state, and there will be some degree of friction between them as they run. occurs.

On the other hand, when a magnetic head is brought into contact with the magnetic disk of the present invention, the convex portion in the circumferential direction is separated by diagonal texture marks, so that a state close to point contact occurs, and the magnetic head The contact area between the magnetic disk and the magnetic disk is extremely small. Therefore, the frictional force against the magnetic disk is reduced, and the damage to the magnetic disk is also reduced, so that durability can be improved. Further, since the inclination angle of the diagonal texture marks is 5 to 30 degrees, sufficient shape magnetic anisotropy is ensured in the circumferential direction, and the electromagnetic conversion characteristics are not deteriorated.

0012

EXAMPLES The present invention will be explained below with reference to specific examples, but it goes without saying that the present invention is not limited to these examples. In the magnetic disk of this embodiment, as shown in FIG. Layer 4 is formed.

The Ni--P plating film 2 is formed on an aluminum substrate 1.
This is provided for the purpose of increasing the surface hardness of the Ni-P plating film 2 and ensuring adhesion to the magnetic layer 4. Therefore, in hard disks, the aluminum substrate 1 with the Ni-P plating film 2 formed on the surface is used as a rigid substrate. be handled. Further, the base layer 3 made of a Cr film is formed by depositing a magnetic layer 4 on the base layer 3.
It is provided to control crystallinity etc. when forming by sputtering etc., and has the effect of improving magnetic properties (eg coercive force etc.).

As the magnetic layer 4 formed on the underlayer 3, any conventionally known magnetic material can be used, but in this embodiment, a Co--Ni--Cr film formed by sputtering is used. Further, on this magnetic layer 4, a protective film 5 using carbon and a lubricant layer 6 are sequentially laminated.

In the magnetic disk constructed as described above, the surface of the rigid substrate, that is, the surface of the Ni--P plating film 2 formed on the aluminum substrate 1, has the following properties as shown in FIG.
Texture marks are provided in the circumferential direction and in a direction forming a predetermined angle θ with respect to the circumferential direction (the tangential direction of the circumference). The above angle θ is as follows: +θ is the angle made clockwise with respect to the circumferential direction, and −θ is the angle made counterclockwise with respect to the circumferential direction.
It should be within the range of ±5 to 30 degrees with respect to the circumferential direction.

Depending on the surface shape of the Ni--P plating film 2 provided with such texture marks, the base layer 3 is
The surface of the magnetic layer 4 is made to have fine irregularities. The surface roughness due to the texture treatment is set at a center line average roughness Ra of 50 to 50 for the purpose of improving the squareness and lowering the coefficient of friction of the magnetic layer 4 with respect to the magnetic head.
The thickness is preferably 500 Å. If it is out of these ranges, the squareness will deteriorate and noise will increase, and the effective coefficient of friction of the magnetic layer 4 with respect to the magnetic head will increase, resulting in decreased durability.

In the magnetic disk constructed as described above, fine irregularities are formed on the surface of the magnetic layer 4 according to the surface shape of the textured Ni--P plating film 2, so that a good Shape magnetic anisotropy improves squareness. Furthermore, when a magnetic head is brought into contact with this magnetic disk, the contact area with the magnetic head is reduced, so the durability of the magnetic disk is improved due to a reduction in the coefficient of friction.

[0018] Such a magnetic disk is manufactured as follows. First, a Ni--P plating film 2 is formed on an aluminum substrate 1 by electroless plating. Then, while rotating the aluminum substrate 1, a texture treatment is applied to the surface of the Ni--P plating film 2. At this time, by appropriately changing the rotational speed of the aluminum substrate 1, the swinging speed of the wrapping tape, and the running speed of the wrapping tape,
The angle θ of the texture marks formed on the surface of the Ni-P plating film 2 with respect to the circumferential direction of the aluminum substrate 1 can be adjusted. By this texture treatment, texture marks are provided on the surface of the Ni--P plating film 2 in the circumferential direction and at an angle of 5 to 30 degrees with respect to the circumferential direction.

Next, a base layer 3 made of a Cr film is deposited on the textured Ni--P plating film 2 by sputtering using a Cr target. Subsequently, a magnetic layer 4 is formed on the underlayer 3 by sputtering using a Co-Ni-Cr alloy as a target. This sputtering can also be performed continuously with the sputtering for forming the base layer 3 described above. Note that sputtering conditions may be selected as appropriate.

Furthermore, a protective film 5 made of carbon is formed on the magnetic layer 4 by continuous sputtering, and a lubricant layer 6 is further deposited on the protective film 5 to obtain a magnetic disk. Note that in the magnetic disk of this embodiment, the magnetic layer 4
Co-
Although a Ni-Cr film was used, other methods include a ferromagnetic metal thin film formed by electrolytic plating, electroless plating, or ion plating, or a magnetic film formed by applying a magnetic paint mainly composed of magnetic powder and a binder. Any conventionally known magnetic material such as a film can be used.

The magnetic anisotropy ratio of the magnetic disk obtained as described above was investigated. FIG. 3 shows the magnetic anisotropy ratio (vertical axis) when the angle θ (horizontal axis) of the texture marks formed on the surface of the Ni-P plating film 2 with respect to the circumferential direction of the aluminum substrate 1 is changed. ) represents a change in The magnetic anisotropy ratio is the ratio of the magnetic anisotropy in the circumferential direction to the magnetic anisotropy in the radial direction of the magnetic disk, and here it is expressed as the ratio of the coercive force HC in the radial direction and the circumferential direction. . As a result, Figure 3
As shown in , the higher the uniformity of the circumferential component, the larger the magnetic anisotropy ratio becomes, but when the angle θ to the circumferential direction is 3
It was found that even in the case of 0°, a sufficiently large magnetic anisotropy ratio is exhibited.

Next, a magnetic disk (comparative example) was prepared using the same method as the magnetic disk of this example, except that texture marks were added only in the circumferential direction for comparison with the magnetic disk of this example. When the durability of each was examined using , the results shown in FIG. 4 were obtained. From Figure 4, compared to the case where texture marks are applied only in the circumferential direction, durability is clearly improved when texture marks are applied at an angle of 5 to 30 degrees to the circumferential direction. It was found that there was very little damage to the surface of the magnetic disk.

[0023]

As described above, in the present invention, texture marks are provided on the surface of the rigid substrate at an angle of 5 to 30 degrees with respect to the circumferential direction, so that it is difficult to bring the magnetic head into contact with the magnetic disk. When this happens, the contact area of the magnetic disk with the magnetic head becomes extremely small. Therefore, damage to the magnetic disk due to friction with the magnetic head is suppressed, and durability is improved. In addition, since the texture marks are formed at an angle of 5 to 30 degrees with respect to the circumferential direction of the rigid substrate, sufficient shape magnetic anisotropy can be ensured, resulting in excellent electromagnetic conversion characteristics. A magnetic disk can be obtained.

[Simple drawing explanation]

FIG. 1 is a sectional view showing the structure of a magnetic disk to which the present invention is applied.

FIG. 2 is a plan view showing the surface shape of a textured aluminum substrate.

FIG. 3 is a characteristic diagram showing the magnetic anisotropy ratio when the angle θ of the texture marks formed on the surface of the aluminum substrate is changed with respect to the circumferential direction of the aluminum substrate.

[Fig. 4] C of a magnetic disk with texture marks applied only in the circumferential direction of the substrate and a magnetic disk with texture marks applied at an angle of 5 to 30 degrees with respect to the circumferential direction.
It is a characteristic diagram showing the relationship between the number of SS and the coefficient of friction.

[Explanation of symbols]

1...Aluminum substrate 2...Ni-P plating film 4...Magnetic layer

Claims (1)

[Claims] 1. A magnetic disk comprising a magnetic layer provided on a rigid substrate, characterized in that the surface of the rigid substrate is provided with texture marks forming an angle of 5 to 30 degrees with respect to the circumferential direction. magnetic disk.