JPH08212541A - Magnetic disk - Google Patents

Abstract

PURPOSE: To obtain a magnetic disk not causing the attraction of the slider of a magnetic head to the disk and prolonging the service life of the slider of the magnetic head. CONSTITUTION: The surface of a magnetic disk is roughened so that the difference between the average height of the resultant ruggedness and the peak height (Rp) is regulated to 100-500Å and the ratio of the difference between the average height and the valley (Rv) to that between the average height and the peak height (Rp) is regulated to 0.3-1.0.

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 for data storage means such as a computer.

[0002]

2. Description of the Related Art There is a hard disk drive device as a data storage means of a computer or the like. In order to obtain excellent high-density magnetic recording characteristics as a medium used in this hard disk drive, a cobalt alloy was deposited on the surface of a magnetic thin film medium substrate by a thin film forming technique such as vapor deposition, sputtering, plating, or ion plating. Things have been developed. As these magnetic thin film medium substrates, an aluminum alloy substrate which is mirror-finished after alumite treatment or an aluminum alloy substrate which is mirror-finished after NiP plating treatment,
Alternatively, a mirror-finished glass substrate is used. However, recently, as hard disk drive devices have become smaller and lighter, magnetic head contact start / stop type hard disk drive devices have become necessary, and the lubricity and durability of the disk surface and the contact head・ Problems such as adsorption between discs are becoming more important.

[0003]

In a contact start / stop type hard disk drive device,
A hard disk drive device having a magnetic disk with a mirror-finished surface condition has a large friction coefficient between the magnetic disk and the magnetic head when the magnetic disk is started or stopped, and the magnetic disk or the magnetic head is damaged, so-called head crash. May occur. In order to reduce the friction coefficient which causes this problem and improve durability, measures such as coating the surface of the magnetic disk with a solid lubricant or a liquid lubricant have been taken. However, the value Rp from the deepest valley of the unevenness of the surface to the maximum peak after mirror finishing
When a liquid lubricant or moisture adsorbing water vapor in the atmosphere is trapped between the surface of the magnetic disk treated with v of 200 Å or less and the magnetic head due to a capillary phenomenon and the hard disk drive is stopped, the magnetic disk and the magnetic head are stopped. May cause strong adsorption phenomenon to each other. This adsorption phenomenon exerts a strong load on the magnetic head and the flexure that is the magnetic head support at the time of starting the magnetic disk drive device, causing damage to the magnetic head and the flexure and causing a strong scratch on the surface of the magnetic disk. Further, these phenomena may cause a head crash, which may render the magnetic disk drive device unusable. Therefore, in order to avoid the adsorption phenomenon between the magnetic head and the magnetic disk, it is conceivable to roughen the surface state of the magnetic disk so as not to adsorb. But,
If surface treatment is simply applied to roughen the surface state, protrusions may be partially generated as shown in FIGS. 4 and 6, and the flying stability of the magnetic head deteriorates. As a result, reproduction output decreases, In some cases, problems such as a decrease in signal-to-noise and an increase in the number of errors could occur.

[0004]

In order to solve the above problems, the magnetic disk of the present invention has a roughened surface, and the value Rp from the average to the maximum peak of the unevenness of the rough surface and the unevenness of the surface. The ratio Rp / Rv with the value Rv from the average to the deepest valley is set in the range of 0.3 to 1.0, and the height of the apex of the convex portion from the average line of the unevenness is set in the range of 100 to 500Å. .

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention has a magnetic layer on a substrate, and the surface on which magnetic recording is performed is made rough so that the highest protrusion of the rough surface is obtained. The difference between the height of the convex portion and the average height of the unevenness should be in the range between 100Å and 500Å, and the difference between the height of the highest convex portion of the rough surface and the average height of the unevenness By setting the ratio of the difference between the height of the lowest concave portion of the rough surface and the average height of the concave and convex to be in the range of 0.3 to 1.0, the surface of the magnetic disk can be appropriately adjusted. The rough surface eliminates the attraction between the magnetic disk and the magnetic head, and the high protrusions are partially eliminated to stabilize the floating of the magnetic head.

Embodiments of the present invention will be described below. FIG. 1 is a sectional view of a main part of a magnetic disk according to an embodiment of the present invention. An aluminum alloy substrate 1 having a diameter of 3.5 inches was coated with a NiP plating film 2 of 20 μm. This N
By lapping and polishing the iP-plated aluminum alloy substrate 1, a 3.5-inch diameter aluminum alloy substrate 1 having a surface precision with a value Rpv from the deepest valley of the surface irregularities to the maximum peak is 200 Å or less. Multiple sheets were prepared. The surface of each of the 3.5-inch aluminum alloy substrates 1 is further lapped using compounds having different grain sizes, and the value Rpv from the deepest valley to the maximum peak and the average line to the maximum peak of the surface shape are obtained. A sample having a value Rp, a value Rv from the average line of the surface shape to the deepest valley, or a ratio Rp / Rv thereof having different values was prepared. After that, the magnetic thin film 3 and the protective film 4 were deposited on each sample by the sputtering method, and the lubricating film 5 was further covered. In addition, a plurality of aluminum alloy substrates 1 different from the above sample are prepared, and polishing is performed in the circumferential direction of the aluminum alloy substrate 1 in the same manner as the above surface processing, and the surface roughness is the same as above. Samples having different values were prepared, and a sputtered film was deposited and a lubricating film 5 was coated. The disk surface of the present embodiment thus formed has a structure as shown in FIGS.

FIG. 2 is a graph showing the result of measuring the state of the unevenness of the surface view in the embodiment of the present invention.
That is, in FIG. 2, a 0.1 × 2.5 μm stylus is moved on the aluminum alloy substrate 1, and the vertical movement of the stylus is taken as the vertical axis.
The horizontal axis is the movement parallel to the plane. FIG. 3 is a graph showing the relationship between the measurement result of the state of the unevenness of the surface and the maximum value average value minimum value of the unevenness. Furthermore, among the sample discs prepared by the above processing method, a plurality of discs having substantially the same Rpv and different Rp / Rv ratios were selected, and defects on the respective disc surfaces were detected by acoustic elastic (Acoustic).
c Elastic) elements were counted by a vanish head provided on a slider made of AlTiC. The result at that time is shown in FIG. As is clear from FIG. 8, when Rp / Rv is 1.0 or less, the number of defects is small. In addition, Rp at this time is 500Å as shown in FIG.
Must be: Furthermore, the above R
Examining the number of times that no abnormalities occurred by repeating contact start stop (hereinafter abbreviated as CSS) for disks with different p / Rv, if Rp / Rv is 0.3 or less as shown in FIG. Less than 20,000 times,
When it is 0.3 to 1.0, it is 20,000 times or more, and when it is 1.0 or more, it is 20,000 times or less. Therefore, it is understood that Rp / Rv must be set to 0.3 to 1.0 in order to make the CSS count 20,000 times or more. Then, when the number of times that an abnormality did not occur by repeating CSS for disks having different Rp values is checked, as shown in FIG.
When SS is less than 20,000 times and Rp is 100Å ~ 500Å, CS
When S is 20,000 times or more and Rp is 500 Å or more, CSS is 20,000 times or less. Therefore, it was also found that the Rp had to be in the range of 100Å to 500Å in order to make the CSS 20,000 times or more. Furthermore, when Rp becomes 100Å or less,
Due to the adsorbed water, the disk and the head adsorbed to each other, causing damage due to the head crash. Also, Rp is 50
If surface treatment is performed using a rough abrasive of 0 Å or more, abnormal protrusions may occur as shown in Fig. 9, causing the slider to float in an unstable state, causing the disc to stop rotating. Then, when the slider comes into contact with the disk, the slider and the disk may hit hard, eventually resulting in a head crash when the CSS count is 20,000 or less.

Next, an embodiment will be described in which the NiP plated film 2 on the surface of the disk is mirror-finished, and then polishing is performed while rotating the disk. FIG. 12 is a graph showing the results of measuring the surface irregularities of the magnetic disk of the present invention along the circumferential direction, and FIG. 13 is a graph showing the results of measuring the surface irregularities of the magnetic disk along the radial direction. Here, the height of the unevenness was measured by bringing the stylus into contact with the surface of the disk by moving the stylus with the surface of the disk by moving the stylus with the stylus relative to the disk. Many samples were created in this way, and the Rp in the radial direction of this sample was 1
Fig. 1 shows the results of examining the relationship between the Rp in the circumferential direction and the number of CSSs by selecting those within the range of 00Å to 500Å.
4 shows. As is clear from FIG. 14, Rp in the circumferential direction
It was found that the CSS number was improved to 60,000 or more when the value was 150 Å or less.

Although the magnetic thin film 3 is formed by the sputtering method in the present embodiment, the same effect can be obtained by forming the magnetic thin film 3 by the plating method or the like.

[0010]

As described above, the magnetic disk of the present invention is
The surface is made rough so that the difference between the average height and the maximum height of the unevenness of the rough surface is in the range of 100 Å to 500 Å, and the average height and the minimum height for the difference between the average height and the maximum height are the same. Since the height difference ratio of the magnetic head is set to be in the range of 0.3 to 1.0, the slider of the magnetic head does not stick to the magnetic disk, and the slider of the magnetic head does not become magnetic during contact start / stop. The slider of the magnetic head has a long life because it does not crash on the disk surface.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a magnetic disk according to an embodiment of the present invention.

FIG. 2 is a graph showing the results of measuring the state of unevenness on the same surface view.

FIG. 3 is a graph showing the relationship between the measurement results of unevenness on the surface and the average value of the highest value and the lowest value of the unevenness.

FIG. 4 is a graph showing the results of measuring the state of irregularities on the surface of a conventional magnetic disk.

FIG. 5 is a graph showing the results of measuring the state of irregularities on the surface of the magnetic disk of the present invention.

FIG. 6 is a cross-sectional perspective view of a main part of a conventional magnetic disk.

FIG. 7 is a cross-sectional perspective view of a main part of a magnetic disk according to an embodiment of the present invention.

FIG. 8 is a graph showing the relationship between the number of defects and the ratio of the maximum value and the minimum value of unevenness.

FIG. 9 is a graph showing the relationship between the maximum unevenness and the number of defects.

FIG. 10 is a graph showing the relationship between the number of CSS times and the ratio of the maximum value and the minimum value of the unevenness.

FIG. 11 is a graph showing the relationship between the maximum value of unevenness and the number of CSS times.

FIG. 12 is a graph showing the results of measuring the surface irregularities of the magnetic disk of the present invention along the circumferential direction.

FIG. 13 is a graph showing the results of measuring the surface irregularities of the magnetic disk along the radial direction.

FIG. 14 is a graph showing the relationship between the maximum number of irregularities and the number of CSS times.

[Explanation of symbols]

 1 Aluminum alloy substrate 2 NiP plating film 3 Magnetic thin film 4 Protective film 5 Lubrication film

Claims (1)

[Claims] 1. A magnetic layer is provided on a substrate, and a surface on which magnetic recording is performed is made rough so that the difference between the height of the highest projection of the projections of the rough surface and the average height of the unevenness is 100Å to 5
The average height of the concave portions and the concave portion of the concave portions of the rough surface with respect to the difference between the height of the highest convex portion of the convex portions of the rough surface and the average height of the concave and convex portions of the convex portion of the rough surface. A magnetic disk, characterized in that the ratio of the height difference between the two is in the range of 0.3 to 1.0.