JPH06103564A - Magnetic disk - Google Patents

Abstract

PURPOSE:To lower sliding resistance by increasing the hardness of a contact.start.stop (CSS) region. CONSTITUTION:The prescribed range on the inner side in the diametral direction of a disk 1 is formed as the CSS region 2 having a contact state with a magnetic head. A prescribed region on the outer side of the diametral direction of the region 2 is formed as a data region 3 to be subjected to information processing by the magnetic head. A ground layer and magnetic layer having a relatively low hardness forming the region 2 are formed to the thickness smaller than the thickness of the ground layer and magnetic layer having the low hardness forming the region 3 and, therefore, the hardness over the entire part of the region 2 is formed higher than the hardness over the entire part of the region 3, thereby, the CSS characteristics are improved. The sliding resistance between the magnetic head and the magnetic disk is lowered as the disk is formed in such a manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk mounted in a magnetic storage device used as an external storage device of a computer or the like, in which information is recorded / reproduced / erased by a relative moving magnetic head.

[0002]

2. Description of the Related Art Generally, a magnetic storage device such as a flexible disk device (FDD) or a hard disk device (HDD) is widely used as an external storage device such as a computer. And, in these FDD, HDD, etc.,
A magnetic head for recording / reproducing / erasing information,
A magnetic disk is mounted which moves relative to the magnetic head and stores predetermined information at a desired position.

Explaining the HDD, when the HDD is not movable, the magnetic disk is stopped and the magnetic disk and the magnetic head are in contact with each other.
When information processing such as recording, reproducing, and erasing of information is performed on the magnetic disk, the magnetic disk is rotated to bring the magnetic disk and magnetic head in contact with each other. Levitate a desired amount, move the magnetic head to a predetermined position on the magnetic disk,
It is so-called CSS (contact start stop) in which a predetermined signal is sent from a magnetic head to a magnetic disk to perform desired information processing.

Explaining the magnetic disk, the magnetic disk is formed by sequentially forming an appropriate underlayer, a magnetic layer, and a protective layer on an annular substrate made of an appropriate non-magnetic material such as glass. Has been done. A predetermined area on the inner side of the magnetic disk on the axial center side is a CSS area where the magnetic disk and the magnetic head are in contact with each other, and the magnetic head floats and runs outside the CSS area in the radial direction. An appropriate data area for processing is formed.

That is, as described above, the structure of the CSS area and the data area is a multilayer structure of the same structure in which an appropriate underlayer, magnetic layer and protective layer are sequentially formed on the annular substrate. The area is divided according to the presence / absence of contact between the magnetic disk and the magnetic head.

Here, the stopped state and the flying running state of the magnetic head will be further described.

When the magnetic disk is stopped, the magnetic head is in contact with the surface of the magnetic disk with a predetermined contact force by the spring pressure of a head supporting member called a gimbal plate which supports itself.

Then, when the HDD is operated, the magnetic disk starts to rotate in a state of being in contact with the magnetic head. Further, as the rotational speed of the magnetic disk increases, the lift force due to the air flow generated on the surface of the magnetic disk increases, and when this lift force becomes larger than the contact force of the magnetic head with respect to the magnetic disk, the magnetic head gently moves from the surface of the magnetic disk. It floats and floats on the magnetic disk while maintaining a desired flying height determined by the shape of the magnetic head, the contact force, and the peripheral speed of the magnetic disk.

That is, the magnetic head slides and rubs the surface of the magnetic disk until just before the magnetic head starts to fly over the magnetic disk. For this reason,
Either the surface of the magnetic disk, the medium facing surface of the magnetic head that contacts the magnetic disk, or both wear due to sliding resistance, and in some cases the frictional force increases abnormally, causing surface destruction of the magnetic disk ( In some cases, the contents recorded on the magnetic disk could not be read out due to a surface crash). In addition, when the sliding resistance (friction force) between the magnetic head and the magnetic disk increases abnormally to a value equal to or higher than the rotational torque of the magnetic disk, the magnetic disk does not rotate and the HDD cannot start. there were.

Further, the surface of the magnetic head which is in contact with the magnetic disk is mirror-finished, and the surface of the magnetic head is also mirror-finished. Adhesion is caused by the contact between the mirror surfaces. There is also a problem in that the HDD may be stuck due to adsorption, leading to a failure of the HDD.

Therefore, in order to solve such a problem, a non-uniform fine unevenness called a texture is conventionally provided on the surface of a substrate of a magnetic disk by machining or chemical etching to form a magnetic disk and a magnetic head. A magnetic disk has been proposed in which the contact area of the contact portion of the magnetic disk is reduced. Furthermore, recently, a magnetic disk in which a projection of a predetermined shape is formed on the surface of the substrate of the magnetic disk by using photolithography called photolithography can control the shape and position of the projection. ,
It has been proposed and put into practical use for reasons such as stability of quality such that the same product can always be stably manufactured.

[0012]

However, in the above-mentioned conventional magnetic disk, since the unevenness is formed on the surface of the magnetic disk, the number of processing steps for creating the unevenness is increased and the quality of the unevenness is largely maintained. However, there is a problem in that the labor cost is increased and the economic burden is increased.

Further, since the data area and the CSS area have the same structure although the required functions are different, there is a problem that the improvement of the functions of the CSS area is limited. It was

The present invention has been made in view of these points, and overcomes the above-mentioned problems in the conventional ones.
An object is to provide a magnetic disk having a simple structure and excellent characteristics in the CSS area.

[0015]

In order to achieve the above-mentioned object, a magnetic disk of the present invention comprises a data area in which at least a magnetic layer and a protective layer are sequentially formed on a surface of a substrate,
It has a CSS area harder than the hardness of the data area.

[0016]

The present invention is based on the following facts discovered by the present inventors in the research of magnetic storage devices such as magnetic heads and magnetic disks, which have been earnestly studied for many years.

That is, the CSS characteristics correlate with the mechanical characteristics of the CSS region, in particular, the hardness, and the higher the hardness, the better the CSS characteristics.

Generally, the relationship between the magnetic head and the magnetic disk is such that the contact area is controlled by a non-uniform fine structure called a texture in terms of CSS characteristics and the surface of the magnetic disk is reduced in order to reduce the flying characteristics. It is necessary to reduce the roughness. Here, it has been clarified that the increase in the contact area with the increase in the number of CSSs is due to the flattening due to the deformation of the magnetic disk rather than the wear of the magnetic disk. This factor has a great influence as the flying height decreases, that is, the surface roughness of the magnetic disk decreases.

The present invention uses the above-mentioned fact in a magnetic disk. According to the magnetic disk of the present invention having the above-mentioned structure, the hardness of the CSS area of the magnetic disk is
Since it can be made harder, CSS for magnetic disks
The characteristics of the region can be improved.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

1 and 2 show a first embodiment of a magnetic disk according to the present invention, FIG. 1 is a plan view showing an essential part of the entire magnetic disk, and FIG. 2 is a constitution of the essential part. FIG.

As shown in FIG. 1, the magnetic disk 1 of this embodiment is formed in an annular shape having an appropriate thickness as in the conventional case. A predetermined area on the inner side in the radial direction is a CSS area 2 that is in contact with a magnetic head (not shown).
A predetermined area outside the S area 2 in the radial direction is a data area 3 where information processing is performed by a magnetic head (not shown).

As shown in FIG. 2, the magnetic disk 1 includes one of the substrates 4 which is made of metal, glass, resin, aluminum alloy, Ni-P plated, or any other suitable material in an annular shape. An appropriate underlayer 5, magnetic layer 6, and protective layer 7 having a predetermined thickness are sequentially formed on the front surface or both front and back surfaces. Each of these layers 5, 6 and 7 is formed of chromium (C
A relatively low hardness Cr layer or the like is used as the material of r), and a cobalt (Co) alloy-based magnetic layer of the relatively low hardness is used as the magnetic layer 6. Carbon (C) having a relatively high hardness as the protective layer 7
Etc. are used.

Further, the CSS area 2 is a data area 3
Unlike the above, it is not necessary to have the magnetic recording characteristics of the same performance as the data area 3. That is, as long as it has magnetic recording characteristics for servo signal processing, the thicknesses of the underlayer 5a and the magnetic layer 6a in the CSS area 2 are the same as those in the data area 3.
Is formed thinner than the underlying layer 5b and the magnetic layer 6b.

Therefore, the CSS area 2 of this embodiment is
The thickness of each of the layers 5a, 6a, 7 in FIG. It is said that. Then, each layer 5 in the data area 3
The thicknesses of b, 6b and 7 are, for example, 7 times the thickness of the underlayer 5b.
The magnetic layer 6b has a thickness of about 0 to 1000 angstroms.
Is about 500 angstroms, and the thickness of the protective layer 7 is about 300 angstroms.

The underlayer 5 and the magnetic layer 6 at the boundary between the CSS region 2 and the data region 3 are connected while continuously changing their thicknesses.

A method of manufacturing the magnetic disk 1 of this embodiment will be described.

The method of manufacturing the magnetic disk 1 of this embodiment is as follows.
Each layer 5, 6, and 7 is formed on the substrate 2 by a known thin film forming method such as sputtering as in the conventional case. And
Only when the base layer 5 and the magnetic layer 6 are formed on the substrate 2, the portion to be the CSS region is appropriately masked.

Next, the operation of this embodiment having the above-mentioned structure will be described.

According to the magnetic disk 1 of this embodiment, the CS
The underlayer 5a and the magnetic layer 6a having a relatively low hardness formed in the S region 2 are formed to be thinner than the underlayer 5b and the magnetic layer 6b having a relatively low hardness formed in the data region 3. Therefore, the hardness of the CSS area 2 as a whole can be made harder than the hardness of the data area 3 as a whole, and the CSS characteristics of the CSS area 2 can be improved.

The underlayer 5a and the magnetic layer 6a formed in the CSS region 2 are better as they are thinner, and may be removed as an extreme example. When the boundary portion is formed by continuously changing the thickness, a magnetic head (not shown) is brought into contact with C.
The followability when flying from the SS area 2 to the data area 3 is improved. It should be noted that the magnetic head is not particularly limited to this embodiment as long as it has a shape capable of ensuring the followability during flying of the magnetic head.

A lubricating layer containing a fluorine-containing lubricant such as perfluoropolyether may be provided on the surface of the protective layer 7.

Next, the operation of this embodiment will be further described by exemplifying a concrete experimental example.

Experimental Example 1 The conventional CSS region (data region 3) has a hardness of 100, for example, a thin film hardness meter (manufactured by NEC Corporation: MHA-40).
0) to about 25 GPa and the thickness of the underlayer 5a and the magnetic layer 6a in the CSS region 2 of this embodiment to be thin so that the hardness of the CSS region 2 is 150 (up by 50%), for example, the thin film hardness. Total (Made by NEC Corporation: MHA
As a comparative experiment, an experiment was conducted to investigate the relationship between the number of CSS times and the frictional force, using the magnetic disk 1 of about -400) at about 38 GPa. The frictional force is measured by using a load cell with the frictional force (sliding resistance with the magnetic head) when the magnetic disk is rotated once at a rotation speed of 1 rpm after performing CSS a predetermined number of times. Is.

The experimental results are shown in FIG. As is clear from the results of this experiment, it was found that the magnetic disk 1 of the present invention was stable with almost no increase in frictional force with respect to the increase in the number of CSSs, as compared with the conventional magnetic disk.

As described above, by increasing the hardness of the CSS region 2, the CSS characteristics can be improved, so that the surface of the magnetic disk, such as a conventional magnetic disk, has fine unevenness called fine texture. It is not necessary to strictly control the height, and the economic burden can be reliably reduced.

It should be noted that it is not denied that the surface of the magnetic disk 1 of the present embodiment is provided with uneven fine irregularities called texture.

FIG. 4 shows a second embodiment in which the magnetic disk of the present invention is used for the HDD system magnetic disk which does not require performance such as magnetic recording characteristics or servo signal magnetic recording characteristics in the CSS area 2a. In the magnetic head 1a of the present embodiment, one surface of the substrate 4 which is annularly made of an appropriate material such as metal, glass, resin, aluminum alloy Ni-P plated, Alternatively, the CSS area 2a and the data area 3 which are made of different materials and have different structures are formed on both front and back surfaces.

The CSS area 2a is formed on the substrate 4.
From an underlayer 5c made of a suitable hard material such as SiC, W, diamond-like carbon, and Ti having a thickness of about 1500 angstroms, and an appropriate hard material such as C having a thickness of about 300 angstroms. The protective layer 7 is formed in that order.

The data area 3 has a thickness of 1000 on the substrate 4, similar to the data area of a conventional magnetic disk.
An underlayer 5b made of a suitable material having a relatively low hardness such as Cr having a thickness of about angstroms, and a magnetic layer 6b made of a suitable material having a relatively low hardness such as a Co alloy system having a thickness of about 500 angstroms. A protective layer 7 made of an appropriate material having a relatively high hardness such as C of about 300 angstroms is sequentially formed. The other structure is the same as that of the magnetic disk 1 of the first embodiment described above.

The base layer 5c formed in the CSS region 2a may be made of any material that does not affect the magnetic properties, is easy to deposit, and has a high hardness. It is not limited.

Next, the operation of this embodiment having the above-mentioned structure will be described.

According to the magnetic disk 1a of this embodiment, C
Since the thickness of the underlayer 5c formed in the SS region 2a is made equal to the thickness of the underlayer 5b and the magnetic layer 6b formed in the data region 3, the surface of the CSS region 2a and the surface of the data region 3 are different from each other. The CSS area 2a can be made to be flush with each other, and the hardness of the CSS area 2a can be made harder than that of the data area 3, so that the CSS characteristics of the CSS area 2 can be improved. Then, the CSS area 2a
The data area 3 and the data area 3 are formed so that their surfaces are flush with each other, and the CSS of the magnetic head (not shown) described above.
It is possible to ensure the smoothness of the floating running at the boundary between the area 2a and the data area 3.

Next, the operation of this embodiment will be further described by exemplifying a concrete experimental example.

Experimental Example 2 The conventional CSS area (data area 3) has a hardness of 100, for example, a thin film hardness meter (manufactured by NEC Corporation: MHA-40).
0), the hardness of the CSS region 2a is set to 300 (300% increase) by using a magnetic disk having a hardness of about 25 GPa and a hard material for the underlayer 5c of the CSS region 2a of the present embodiment, for example, a thin film hardness tester. (Made by NEC Corporation: MHA
Magnetic disk 1a of about 75 GPa at -400)
As a comparative experiment, an experiment was conducted to investigate the relationship between the number of CSSs and the frictional force. The frictional force is measured by using a load cell with the frictional force (sliding resistance with the magnetic head) when the magnetic disk is rotated once at a rotation speed of 1 rpm after performing CSS a predetermined number of times. Is.

The experimental results are shown in FIG. As is clear from the results of this experiment, it was found that the magnetic disk 1 of the present invention was stable with almost no increase in frictional force with respect to the increase in the number of CSSs, as compared with the conventional magnetic disk.

Even with such a configuration, the above-mentioned first
The same effect as that of the embodiment can be obtained.

The present invention is not limited to the above embodiment, but can be modified as necessary.

[0049]

As described above, according to the magnetic disk of the present invention, by increasing the hardness of the CSS area of the magnetic disk where the magnetic head and the magnetic disk come into contact,
It has extremely excellent effects such as reduction of sliding resistance between the magnetic head and the magnetic disk.

[Brief description of drawings]

FIG. 1 is a plan view showing an essential part of an entire first embodiment of a magnetic disk according to the present invention.

FIG. 2 is an enlarged vertical sectional view showing the configuration of the main part of FIG.

FIG. 3 is a diagram showing the relationship between the number of CSS times and the frictional force in the first embodiment.

FIG. 4 is a view similar to FIG. 2 showing a second embodiment of the magnetic disk according to the present invention.

FIG. 5 is a diagram showing the relationship between the number of CSS times and frictional force in the second embodiment.

[Explanation of symbols]

 1, 1a Magnetic disk 2, 2a CSS area 3 Data area 4 Substrate 5, 5a, 5b, 5c Underlayer 6, 6a, 6b Magnetic layer 7 Protective layer

Claims (1)

[Claims] 1. A magnetic disk comprising a data area in which at least a magnetic layer and a protective layer are sequentially formed on a surface of a substrate, and a CSS area harder than the hardness of the data area.