JPH06259911A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To improve the sliding reliability of the magnetic disk device by lessening the attraction of a magnetic head to a thin-film type magnetic disk by a lubricant used for this magnetic disk. CONSTITUTION:The slider 10 of the magnetic head of the magnetic disk device using the magnetic disk of the thin-film type stuck with the lubricant on the surface in order to lessen the wear of the magnetic disk and the magnetic head and the slider surface side of a recording and reproducing element part 11 fixed to the end of the slider 10 are coated by a fluorocarbon film 12 having the property to make these parts hardly wettable with water. As a result, the magnetic head is hardly attracted to the magnetic disk even if the lubricant absorbs the moisture in the air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device having high reliability of sliding between a magnetic disk and a magnetic head.

[0002]

2. Description of the Related Art FIG. 6 is a sectional view showing the structure of a general magnetic disk device. In the figure, in the conventional magnetic disk device, a magnetic head 4 for generating a recording signal magnetic field supported by a light weight suspension spring 3 is arranged on the surface of a magnetic disk 2 mounted on a spindle 1. It is configured. The positioning control of the magnetic head 4 with respect to the magnetic disk 2 is performed by moving the magnetic head 4 to a target track position on the surface of the magnetic disk 2 by the servo motor 5.

FIG. 7 is a cross-sectional view showing the relationship between the magnetic head and the surface of the magnetic disk in an example of a conventional magnetic disk device, and FIG. 7 (a) shows the state when the magnetic disk is stationary (when not in operation). FIG. 7B shows the state when the magnetic disk is rotating (during operation).

From the viewpoint of the reliability of the magnetic disk device, it is desirable that the magnetic head and the magnetic disk are not in contact with each other during high speed rotation. Therefore, in most cases, FIG.
The method shown in (a) and (b) is adopted.

That is, when the magnetic disk is stationary, the magnetic head 4 shown in FIG. 6 is pressed against the surface of the magnetic disk 2 by the suspension spring 3 as shown in FIG. 7A. Has become. Further, when the magnetic disk is rotating, as shown in FIG. 7B, the slider 10 is levitated by the airflow 6 generated by the rotation of the magnetic disk 2, and the recording / reproducing element unit 11 is moved to the magnetic disk 2 by the airflow 6. It is in a state of being levitated from above the surface of the sheet through a predetermined levitating spacing 7. This is Contact Start
It is called the Stop (CSS) method.

In order to improve the storage capacity of a magnetic disk device, which has been increasingly demanded in recent years, while improving the encoding technology for recording / reproducing signals, the magnetic field formed on the surface of the magnetic disk 2 is being improved. It has been attempted to thin the recording medium to increase the coercive force and to narrow the spacing 7 to improve the linear recording density for the recording medium.

Although the narrowing of the floating spacing is effective for improving the recording density, the magnetic head is used for a magnetic disk which is rotating at a high speed to read / write a recording signal (in operation). Are more likely to come into contact with each other, causing the recorded data to be destroyed and increasing the risk of impairing the reliability of the magnetic disk device.

Therefore, conventionally, by increasing the smoothness of the surface of the magnetic disk 2 to reduce the frequency of contact with the magnetic head 4 during the operation of the apparatus, or by applying the lubricant 8 to the surface of the magnetic disk 2 in advance. A method of suppressing the deterioration of the reliability of the device due to the narrowing of the spacing 7 is implemented by reducing the frictional resistance in the case of contact and preventing the wear of the magnetic disk 2 and the magnetic head 4.

[0009]

In a magnetic disk used in a conventional magnetic disk device, a carbon-based protective film is applied to a metal thin film medium, and an alumina filler is applied to a coating medium. The durability against abrasion is increased to improve the sliding reliability. Further, in order to improve the sliding stability when the magnetic disk is rotated at a high speed, a liquid lubricant of perfluoropolyether type having a low vapor pressure is used.

In the case of a coating type magnetic disk, the lubricant 8 adhered to the disk surface enters the micropores 9 existing in large numbers on the disk surface.
Serves as a supply source of the lubricant 8 to the disk surface. On the other hand, in the case of a thin film type magnetic disk, since the surface is smoothed and the micropores 9 are not present, the lubricant 8 adhered to the disk surface exists only on the surface of the magnetic disk.

Therefore, when the levitation spacing of the magnetic head is narrowed in the magnetic disk drive employing the thin film magnetic disk, the lubricant 8 absorbs moisture in the air as compared with the coating type magnetic disk. Then, the magnetic head is likely to be attracted to the magnetic disk.

If the magnetic disk is rotated while the magnetic disk 2 and the magnetic head 4 are attracted, the magnetic disk may not rotate or the suspension spring supporting the magnetic head may be broken.

Further, even if the magnetic head and the magnetic disk are started to rotate, the frictional resistance between the magnetic head and the magnetic disk becomes large, and the levitation operation until the predetermined levitation spacing is obtained becomes extremely unstable. The magnetic head 4 is easily worn due to friction.

Therefore, it is not always appropriate to increase the amount of the lubricant applied to the surface of the magnetic disk as a means for improving the sliding characteristics.

In the above method of increasing the smoothness of the surface of the magnetic disk to reduce the contact frequency of the rotating magnetic disk with the magnetic head, when a lubricant is present on the smooth disk surface, The absorption of the lubricant between the magnetic head and the magnetic disk becomes remarkable due to the moisture absorption of the lubricant when the disk is stationary (when not in operation). Therefore, CS
The reliability of the S-type levitation operation may be reduced, and the magnetic disk and the magnetic head may be worn at the start of rotation of the magnetic disk.

In JP-A-63-64684, a slider of a magnetic head is coated with a material having a low surface energy such as PTFE (the atomic composition ratio of carbon and fluorine is 1: 2). In order to prevent dust from adhering to the non-contact surface of the slider, a thin film is deposited on the non-contact surface of the slider. No consideration is given to prevention.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to use a magnetic disk having a smooth surface for narrowing the levitation spacing.
Another object of the present invention is to provide a magnetic disk device which prevents the magnetic head from being attracted to the magnetic head due to a lubricant used by being attached to the magnetic disk and which improves the sliding reliability of the magnetic disk device.

[0018]

In order to achieve the above object, the present invention provides a magnetic disk having a magnetic recording layer formed on a substrate, and a slider contacting the surface of the magnetic disk when the magnetic disk stands still. In a magnetic disk device including a magnetic head having a surface, an adsorption prevention film made of a non-hydrophilic material that is hard to wet with water is formed on the slider surface of the magnetic head.

In this magnetic disk device, the slider surface of the magnetic head contacts the surface of the magnetic disk when the device is not in operation (when the magnetic disk is stationary), and the device is in operation (when the magnetic disk rotates at high speed). Uses a so-called CSS method of floating above the surface of the magnetic disk, and a lubricant that reduces frictional resistance is attached to the surface of the magnetic disk.

Further, carbon fluoride (CF _X ) is adopted as the non-hydrophilic material, and the atomic composition ratio of the fluorine atom (F) to the carbon atom (C) of the carbon fluoride (CF _X ) is as described in the above publication. (Teflon (registered trademark) with X = 2.0), X = 0.3 to 1.0, and the thickness of the adsorption preventing film was 3 to 100 nm.

[0021]

The operation based on the above configuration will be described.

According to the inventors of the present invention, as a result of detailed examination of the adsorption phenomenon between the magnetic disk and the magnetic head, the above-mentioned phenomenon can be controlled by controlling the wetting state of water, which is the main cause of adsorption, to the magnetic head. I found that I could solve the problem.

An oxide material is usually used as a material forming the slider of the magnetic head. Since the oxide material has a large surface energy, the lubricant having a small surface energy adhered to the disk surface is likely to be easily transferred to the slider surface of the magnetic head when the magnetic disk is stationary and in contact with the magnetic head. Has become.

In this state, if water is present in the vicinity of the contact area, the water (72 erg / cm ² ) will become a lubricant (20 erg / cm ² ).
Since the surface energy is larger than that of the above, since the moisture is repelled by the lubricant at the beginning, the influence of adsorption due to the condensation of moisture in the air does not clearly appear.

However, when it is in contact with water for a long time, the condensed water gradually replaces the lubricant on the slider surface with the lapse of time, and the attraction force of the slider surface of the magnetic head to the magnetic disk surface increases. Was observed. It should be noted that water replaces the lubricant mainly because the interaction with the slider material is larger than that of the water, but the detailed mechanism is not clear.

As a result of studying various material systems on the basis of the above, by forming a material having poor wettability on water on the slider surface, the lubricant and water in the contact portion between the stationary magnetic disk and the magnetic head and the water are mutually interacted. It was found that it is possible to prevent an increase in the attraction force between the magnetic disk and the magnetic head due to the action.

Preferably, a thin film of carbon fluoride having a small surface energy (chemical formula CF _X : x = 1.0 to 0.3) is formed on the slider surface of the magnetic head as a material that is hard to be wetted by water, thereby preventing adsorption. Can be easily achieved.

Further, since the sliding characteristics of the magnetic head are improved by forming this thin film, the reliability of the magnetic disk device can be greatly improved as compared with the conventional one.

[0029]

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

Embodiment 1 FIG. 1 is a cross-sectional view showing an embodiment of a magnetic head coated with an adsorption prevention film in a magnetic disk device of the present invention. In this embodiment, a thin film type magnetic head is used. The magnetic head comprises a slider 10 and a recording / reproducing element section 11 located at the end of the slider 10. The read / write element unit 11 is a thin film process (Jo
urnal Applied Physics 61 (8), pp4157-4162 (1987)) to form an inductive type thin film head element.

After the thin-film magnetic head is formed, carbon fluoride is used as a target material on the surface of the magnetic head facing the magnetic disk, that is, the slider surface (the lower side of the drawing), and the sputtering method is used. By depositing to a thickness of 100 nm, the carbon fluoride film 12 as an adsorption prevention film is formed by coating.

The conditions of the adsorption test for the magnetic head shown in FIG. 1 are as follows.

For the magnetic disk, the surface of the aluminum substrate is plated with nickel-phosphorus alloy and then processed and polished,
A cobalt-chromium based magnetic medium, which is a magnetic recording medium, is formed into a thin film with a thickness of 60 nm by a sputtering method, and a 40 nm carbon protective film is formed on the surface in contact with the magnetic head. Prepare a predetermined number of sheets with Ra = 5 nm.

Then, a perfluoropolyether type lubricant is adhered to each of the above magnetic disks by a dipping method to prepare magnetic disks having lubricants having different adhesion thicknesses. The thickness of the lubricant is 2 to 30 nm, and the thickness is controlled by changing the concentration of the dip solution.

As the magnetic head, a magnetic head having a carbon fluoride film with a thickness of 30 nm deposited on the slider surface is prepared.

The magnetic head is placed on the surface of an unused magnetic disk of each lubricant film thickness, and the magnetic head is in contact with the surface of the magnetic disk which is stationary (non-operating state). 24 in a constant temperature bath at 90 ° C and 90% relative humidity
After holding for a period of time, the force applied when starting to rotate at 1 rpm from the stationary state is measured as the adsorption strength, and at the same time, the friction coefficient is also measured.

For comparison with this embodiment, a magnetic head not coated with a carbon fluoride film is also
The same measurement as above is performed.

FIG. 2 is a graph showing the adsorption preventing effect of this embodiment (Example 1) and a comparative example thereof. The film thickness of the lubricant adhered to the surface of the magnetic disk and the adsorbing strength of the magnetic head in contact therewith are shown in FIG. Represents the relationship. In the figure,
The film thickness of the carbon fluoride film deposited on the magnetic head is 30 nm, which is the same as in FIG.

In the figure, the vertical axis represents the adsorption strength between the magnetic disk and the magnetic head measured as described above, and the horizontal axis represents the perfluoropolyether attached to the surface of the magnetic disk.
The film thickness of the telluride lubricant is shown. The black circles represent the values measured by the conventional magnetic head not having the carbon fluoride film as the adsorption preventing film, and the white squares represent the values measured by the character head of this embodiment.

As shown in FIG. 2, in the case of using a magnetic head whose slider surface is covered with a carbon fluoride film, regardless of the film thickness of the lubricant, the adsorption strength with respect to the magnetic disk is higher than in the conventional case. Get smaller. Further, since it exhibits excellent stability over time, it is possible to improve the sliding reliability of the CSS flotation type magnetic disk device for a long period of time.

FIG. 3 shows the relationship between the film thickness of the adsorption prevention film, that is, the carbon fluoride film, and the adsorption strength. In the figure, the film thickness of the lubricant attached to the magnetic disk is 15
nm, the atomic composition ratio of carbon atoms and fluorine atoms of the fluorocarbon covering the magnetic head is approximately 1: 1.

As shown in FIG. 3, even if the carbon fluoride film deposited on the magnetic head is an extremely thin film, the effect of preventing adsorption is recognized, but the practical film thickness is about 3 nm or more. Recommended.

Further, if the film thickness is made too thick, it will lead to a large levitation spacing, which is not practical.
The upper limit is about 100 nm. However, in the case of a magnetic disk device capable of increasing the floating spacing, it is possible to make the film thickness of the carbon fluoride film larger.

Example 2 In this example, a fluorocarbon target material having a different CF composition was used to form a film thickness on a stabilized zirconia slider.
A 30 nm thick carbon fluoride film is formed by sputtering.

FIG. 4 is a graph showing the adsorption prevention effect of this embodiment (Embodiment 3), showing the relationship between the atomic composition ratio of the fluorocarbon CF _x constituting the adsorption prevention film, that is, the value X and the adsorption strength. Show.

To obtain this graph, a fluorocarbon target material having different atomic composition ratios of carbon atoms and fluorine atoms was used, and a sputtered film of fluorocarbon having a thickness of 30 nm was formed on each magnetic head. , Its composition EP
After analysis by MA, the magnetic head was held under the same conditions as in Example 1 (temperature: 35 ° C., relative humidity: 90%), and the relationship between the adsorption strength of the magnetic head after 24 hours was examined.

As shown in FIG. 4, when a small amount of F enters C, the effect of preventing the adsorption of the magnetic head is exhibited, but the composition region where the adsorption preventing effect is clearly exhibited is fluorinated carbon CF _x . X = 0.3 to 1. Further, the more desirable composition region for practical use is X = 0.8 to 1.

Example 3 Next, although not shown, as Example 3, a thin film magnetic head using Al ₂ O ₃ —TiC instead of the stabilized zirconia of Examples 1 and 2 and a bulk magnetic head of MnZn ferrite were used. Also, regarding the thickness of the lubricant applied to the magnetic disk,
A confirmation test of the adsorption prevention effect was conducted in the same manner as in Example 1 with a thickness of 15 nm and a film thickness of the carbon fluoride film coated on the magnetic head set to 20 nm. For comparison, the same test was performed on a magnetic head having no carbon fluoride film as in Example 1.

As a result, Al ₂ having a carbon fluoride film was formed.
O ₃ -TiC thin adsorption strength of the magnetic head is 0.7 times the adsorption strength of the conventional Al ₂ O ₃ -TiC thin film magnetic head having no carbon fluoride film, for also MnZn ferrite bulk magnetic head 0.85 It was confirmed that they were improved twice.

Example 4 In this example, a durability test was conducted in order to confirm the effect in an actual magnetic disk device.

FIG. 5 is a graph showing the results of the durability test for Example 4. In the figure, the vertical axis is the normalized friction coefficient showing the ratio of the friction coefficient after the durability test to the friction coefficient (1) measured before the durability test (initial value), and the horizontal axis is the target of the durability test. It is the identification number of the six sets of samples that became.

In this durability test, the magnetic disk device of the present invention having a magnetic head made of stabilized zirconia coated with a carbon fluoride film having a thickness of 20 nm and the conventional magnetic disk device having no magnetic carbon film were used. Six magnetic disk devices were prepared for each. At this time, in any of the magnetic disk devices, the friction coefficient when the magnetic disk was rotated at 1 rpm was measured in advance. A lubricant with a thickness of 8 nm was attached to each magnetic disk.

After performing a CSS sliding test 10,000 times on each magnetic disk device, the friction coefficient when the magnetic disk was rotated at 1 rpm was measured. As a result, the normalized friction coefficient shown by a black circle in FIG. 5 was obtained for the magnetic disk device of the present invention, and the normalized friction coefficient shown by a white square in FIG. 5 was obtained for the conventional magnetic disk device.

That is, the friction coefficient of the magnetic disk device of the present invention was 1.15 times the initial value on average, and the friction coefficient of the conventional magnetic disk device was 1.3 times the same. From this, it was confirmed that the magnetic disk device of the present invention can obtain higher sliding reliability than the conventional one.

In the above Examples 1 to 5, stabilized zirconia and Al were used as the base material of the magnetic head.
An example using three types of slider materials of ₂ O ₃ -TiC and Mn-Zn ferrite has been described, but if there is adhesion to carbon fluoride, a slider material for magnetic heads other than these three types is used. It goes without saying that it can also be applied to.

Further, since the adsorption strength and sliding characteristics are substantially determined by the characteristics of the slider portion of the magnetic head, even if the adsorption prevention film is applied only to the slider portion, it is applied to both the slider portion and the recording / reproducing element portion. Even if it is adhered, the same effect can be obtained. The same effect can be obtained when an MR element (magnetoresistive element) is used instead of the electromagnetic induction type element for reading out the magnetic head magnetic sensing element.

[0057]

As described above in detail, by using the magnetic disk device of the present invention, by forming the adsorption preventing film made of a non-hydrophilic member which is hard to be wetted by water on the slider surface of the magnetic head, It is possible to prevent the attraction force between the magnetic disk and the magnetic head from increasing due to the interaction between the lubricant and water at the contact portion between the stationary magnetic disk and the magnetic head.

As a result, at the start of rotation of the magnetic disk in the magnetic disk device, the suspension spring supporting the magnetic head and the magnetic disk can be prevented from being worn, and the magnetic head can be smoothly moved to the floating state. C
The effect that the sliding reliability of the SS floating type magnetic disk device can be improved is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a magnetic head to which an adsorption prevention film is applied in a magnetic disk device of the present invention.

FIG. 2 is a graph showing the adsorption prevention effect of the first embodiment of the magnetic disk device of the present invention.

FIG. 3 is a graph showing the adsorption prevention effect of the second embodiment of the magnetic disk device of the present invention.

FIG. 4 is a graph showing the adsorption preventing effect of the third embodiment of the magnetic disk device of the present invention.

FIG. 5 is a graph showing a result of an endurance test on a magnetic disk device according to a fifth embodiment of the present invention.

FIG. 6 is a cross-sectional view showing the configuration of a general magnetic disk device.

FIG. 7 is a cross-sectional view showing a relationship between a magnetic head and a magnetic disk surface in an example of a conventional magnetic disk device.

[Explanation of symbols]

 1 Spindle 2 Magnetic Disk 3 Lightly Loaded Suspension Spring 4 Magnetic Head 5 Servo Motor 6 Air Flow 7 Levitation Spacing 8 Lubricant 9 Micropore 10 Slider 11 Recording / Reproducing Element 12 Carbon Fluoride Film

Claims (1)

[Claims] 1. A magnetic disk device comprising: a magnetic disk having a magnetic recording layer formed on a substrate; and a magnetic head having a slider surface which comes into contact with the surface of the magnetic disk when the magnetic disk is stationary. A magnetic disk device, wherein an adsorption preventing film made of a non-hydrophilic material which is hard to get wet is formed on the slider surface of the magnetic head.