JPH05128468A - Levitation type magnetic head - Google Patents

Abstract

(57) [Summary] [Object] To prevent the magnetic head from adsorbing to the magnetic disk and reduce damage to the magnetic disk during CSS, thereby improving the durability of the magnetic head and the magnetic disk. [Structure] A plurality of grooves 8 are formed on an air bearing surface 7 of a floating magnetic head. The groove 8 is composed of a groove substantially in the traveling direction of the slider and a groove intersecting the groove at an angle of 2 to 15 degrees, and the center line average roughness of the air bearing surface is set to 20 to 100Å.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floating magnetic head for a magnetic disk device.

[0002]

2. Description of the Related Art Magnetic disk devices have been used in a wide range of fields for the purpose of storing data, but in recent years, high density magnetic recording has been remarkably advanced along with miniaturization and large capacity. In order to achieve magnetic recording, it is necessary to narrow the recording / reproducing gap and the track width in the floating magnetic head. In addition, magnetic disks have high coercive force,
Thinning is in progress. The structure of a conventional floating magnetic head will be described below with reference to FIG. Figure 3
1 is a perspective view of a conventional flying type magnetic head, in which a magnetic head core is provided at a rear portion of an air bearing surface 11 of a slider 9 formed of a non-magnetic material.
12 is fixed with an adhesive 14 such as glass. Air bearing surface 1
The processing method of 0 and 11 is a wet lapping method using fine diamond abrasive grains, and mirror finishing is performed so that the center line average roughness is 20 Å or less. The operation of the conventional floating magnetic head configured as described above will be described below.
In the current magnetic disk device, the magnetic disk starts to rotate at the time of startup, and when a certain speed is reached, the magnetic head receives buoyancy and floats at a constant flying height, and performs recording / reproduction. When stopped,
The rotation speed of the magnetic disk decreases, the flying height of the magnetic head gradually decreases, and the magnetic disk comes into contact with the magnetic disk and stops. This method is called contact start stop (CSS). Currently, this CSS method is about 0.2 μm
A low flying height is achieved.

[0003]

However, the above-mentioned C
The SS method has a tribological problem. One is CS
When S is repeated, the magnetic disk or the magnetic head is damaged by the contact / sliding between the magnetic head and the magnetic disk,
The magnetic head may not be able to fly normally (hereinafter referred to as head crash). In addition, the magnetic head may be attracted to the magnetic disk while the magnetic disk is stopped, making it difficult for the magnetic disk to rotate when the magnetic disk drive device starts up (hereinafter referred to as sticking). The magnetic head will be damaged or the magnetic disk will not rotate. As a method for preventing a head crash, a magnetic disk has conventionally been coated with a lubricant, but conversely sticking tends to occur. Therefore, in order to prevent this sticking, the surface of the magnetic disk is subjected to surface roughening treatment (texturing) of tens to hundreds of Å to reduce the true contact area of the magnetic disk of the magnetic head. However, when the flying height of the magnetic head becomes smaller when the spacing accompanying the high-density magnetic recording becomes smaller, the sliding distance becomes longer as the time required for the magnetic head to fly above the magnetic disk during CSS becomes longer. There is a problem that the durability of the magnetic recording disk is deteriorated. Therefore, it is necessary to reduce the surface roughness of the magnetic disk in order to shorten the sliding distance, but if the surface roughness of the magnetic disk is reduced,
Since the direct contact area between the magnetic head and the magnetic disk increases, there arises a problem that the magnetic head sticks to the magnetic disk while the magnetic disk is stopped. The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a levitation type magnetic head in which the magnetic head does not stick to the magnetic disk when the durability of the magnetic disk deteriorates or is stopped. is there.

[0004]

In order to achieve the above object, the present invention forms a plurality of grooves on the air bearing surface of a floating magnetic head, and the grooves are approximately in the direction of travel of the slider and the grooves. It is composed of grooves intersecting at 2 to 15 degrees (hereinafter, the angle of the intersecting grooves is referred to as an intersection angle), and the center line average roughness of the air bearing surface is set to 20 to 100Å.

[0005]

According to the present invention, by adopting the above-mentioned structure, the real contact area between the magnetic head and the magnetic disk can be reduced, the magnetic head can be prevented from being attracted to the magnetic disk, and the magnetic head and the magnetic disk can be used during CSS. By reducing the frictional force between them, damage to the magnetic disk by the magnetic head can be reduced, and the durability of the magnetic head and the magnetic disk can be improved.

[0006]

1 is a perspective view of a floating magnetic head according to an embodiment of the present invention, and FIG. 2 is an enlarged plan view of an air bearing surface of a floating magnetic head of this embodiment. In this floating magnetic head, as shown in FIG. 1, a magnetic head core 4 is fixed to an air bearing surface 3 of a slider 1 made of a non-magnetic material in the rear portion with an adhesive 6 such as glass. The air bearing surface is wet-lapped with 1/8 μm diamond abrasive grains and the center line average roughness is 10Å
After that, while rotating the disc with the polishing sheet at an arbitrary number of rotations, slide the magnetic head under a constant load,
As shown in FIG. 2, a plurality of grooves 7 were formed on the air bearing surface. The groove intersects with the groove in the traveling direction of the slider at an angle of 6 degrees, and the center line average roughness of the air bearing surface is 30Å. The groove intersecting the moving direction of the slider is formed by swinging the magnetic head in the radial direction of the disk.
The conventional floating magnetic head has the same structure as that of this embodiment, but the air bearing surface is wet-lapped with 1/8 μm diamond abrasive grains to have a center line average roughness of 10Å. .. In this embodiment, a flying magnetic head having an air bearing surface width of 550 μm (Example 1) and a flying magnetic head having a width of 350 μm (Example 2) were used.

Next, the variation of the static friction coefficient (Δμs) and the variation of the dynamic friction coefficient (μk) were measured for the air bearing surface widths of 550 μm and 350 μm of the floating magnetic head formed as described above. Tables 1 and 2 show the results when the air bearing surface width of the floating magnetic head was 550 μm and when the air bearing surface width was 350 μm.

[0008]

[Table 1]

[0009]

[Table 2]

The change amount (Δμs) of the coefficient of static friction is
The change amount of the static friction coefficient of the magnetic head with the magnetic disk before and after the environmental history was used. As for the environmental history condition, the beginning is
The test was carried out under the conditions of 20 ° C. and 50%, 65 ° C. and 80% for 2 hours, left for 24 hours, and then returned to 20 ° C. and 50% for 2 hours. The amount of change (μk) in the coefficient of kinetic friction was calculated after CSS was performed 20000 times.
This is a measurement of the dynamic friction coefficient between the magnetic head and the magnetic disk when the magnetic disk was rotated at 1 rpm. Here, the flying height of the floating magnetic head having an air bearing surface width of 550 μm is about 0.2 μm, and the flying height of a floating magnetic head having an air bearing surface width of 350 μm is about 0.1 μm.

As a magnetic disk, an aluminum substrate is plated with Ni-P and further textured. An underlayer of Cr, a magnetic layer of Co alloy, and a protective layer of carbon are sputtered in this order, and a lubricant is further applied to about 20Å. A magnetic disk with a centerline surface roughness (Ra) of about 100Å is used for a magnetic head with an air bearing surface width of 550 μm, but a sufficient flying guarantee is provided for a magnetic head with an air bearing surface width of 350 μm. Therefore, a magnetic disk having a centerline surface roughness (Ra) of the texture of about 70Å is used. As shown in Table 1, in the magnetic head having the flying height of 0.2 μm and the air bearing surface width of 550 μm, the dynamic friction coefficient μk is small in both Example 1 and Conventional Example 1, and the variation Δμs of the static friction coefficient is Conventional Example 1 Shows a slight adsorption tendency, but is not a problem. However, as shown in Table 2, in the magnetic head having a flying area of 350 μm, the second embodiment has a much smaller Δμs than the second conventional example. In Conventional Example 2, since the center line surface roughness (Ra) of the texture of the magnetic disk was reduced, the actual contact area between the magnetic head and the magnetic disk was increased, but in Example 2, a deep groove was formed on the air bearing surface. This is probably because the actual contact area between the magnetic head and the magnetic disk did not become so large. Moreover, the dynamic friction coefficient of Example 2 is much smaller than that of Conventional Example 2. In Conventional Example 2, since the center line surface roughness (Ra) of the texture of the magnetic disk was reduced, the actual contact area between the magnetic head and the magnetic disk was increased, but in Example 2, a deep groove was formed on the air bearing surface. As a result, since the actual contact area between the magnetic head and the magnetic disk did not become so large, the frictional force between the magnetic head and the magnetic disk during CSS becomes small, and the damage of the magnetic head to the magnetic disk becomes small. It is considered that the durability of the disc has improved.

In the levitation type magnetic head of Example 2 (350 μm), the center line surface roughness (Ra) of the air bearing surface is 10Å, 20
Magnetic heads of Å, 100Å and 200Å were created. Next, using each of the above floating magnetic heads, the static friction coefficient variation (Δμs) and the dynamic friction coefficient were measured under the same conditions and methods as in Tables 1 and 2.
(μk) was measured. The results are shown in Table 3.

[0013]

[Table 3]

The center line surface roughness of the groove on the air bearing surface is 20 to 100Å
In (-), the true contact area between the magnetic head and the magnetic disk is small, so even if CSS is repeated, the coefficient of dynamic friction μk
Hardly rises. This is because the actual contact area between the magnetic head and the magnetic disk is reduced, and the frictional force between the magnetic head and the magnetic disk during CSS is reduced.
The damage to the magnetic disk of the magnetic head is reduced,
It is considered that the durability of the magnetic head and the magnetic disk is improved. Further, even if it is left under high temperature and high humidity, the magnetic head and the magnetic disk hardly adsorb. It is considered that this is also because the true contact area between the magnetic head and the magnetic disk was reduced due to the deep groove on the air bearing surface. 10Å ()
Then, when CSS is repeated, the coefficient of dynamic friction μk increases.
This is because the actual contact area between the magnetic head and the magnetic disk has increased, and the frictional force between the magnetic head and the magnetic disk during CSS has increased, resulting in greater damage to the magnetic head and the magnetic disk. It is thought that the durability of the is deteriorated. Further, the magnetic head and the magnetic disk are attracted to each other under high temperature and high humidity. It is also considered that this is because the groove is too shallow and the actual contact area between the magnetic head and the magnetic disk becomes large. In addition, 200Å
In (), since the true contact area between the magnetic head and the magnetic disk is small, the magnetic head and the magnetic disk are not adsorbed under high temperature and high humidity, but the CSS repeatedly crashes. It is considered that this is because the groove was too deep and the flying state of the magnetic head became unstable, and the magnetic head damaged the magnetic disk.

Next, in the levitation type magnetic head of Example 2 (350 μm), the crossing angle of the groove line on the air bearing surface was 0 degree (a), 2 degrees.
Magnetic heads of (b), 15 degrees (c) and 30 degrees (d) were created. Using the above floating magnetic heads, the static friction coefficient variation (Δμs) and dynamic friction coefficient were measured under the same conditions and methods as in Tables 1 and 2.
(μk) was measured. The results are shown in Table 4.

[0016]

[Table 4]

When the crossing angle of the groove lines is 2 to 15 degrees (b) to (c), the true contact area between the magnetic head and the magnetic disk is small, so that the dynamic friction coefficient μk hardly increases even if CSS is repeated. This is because the true contact area between the magnetic head and the magnetic disk is reduced, and the frictional force between the magnetic head and the magnetic disk during CSS is reduced, so that the magnetic head is less damaged and the magnetic head and the magnetic disk are reduced. It is thought that the durability of is improved. When the crossing angle is 0 degrees (a) and 30 degrees (d), an abnormal protrusion is generated on the air bearing surface due to the surface processing. Therefore, the abnormal protrusion wears the carbon protective film of the magnetic disk, and the magnetic head and the magnetic head are damaged. It is considered that the durability of the disk has deteriorated. Also,
The magnetic head may be a monolithic type, a composite type, a thin film type, or the like. Further, in this embodiment, the groove is formed on the entire air bearing surface of the floating magnetic head, but the groove may be formed only in the vicinity of the gap.

[0018]

As is apparent from the above embodiment, the present invention forms a plurality of grooves on the air bearing surface of a floating magnetic head with a predetermined crossing angle and center line average roughness. The real contact area is reduced, and as a result, the magnetic head is prevented from being attracted to the magnetic disk, and the frictional force during CSS is further reduced. Therefore, the damage of the magnetic head to the magnetic disk is reduced, and the durability of the magnetic head and the magnetic disk is significantly improved. Further, the reduction of the frictional force between the magnetic head and the magnetic disk makes it possible to reduce the spacing and realize a high recording density. Further, since the attraction between the magnetic head and the magnetic disk can be reduced, since a small motor having a low torque can be used, it is possible to reduce the size and weight of the magnetic disk device.

[Brief description of drawings]

FIG. 1 is a perspective view of a floating magnetic head according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view of an air bearing surface of a floating magnetic head according to an embodiment of the present invention.

FIG. 3 is a perspective view of a conventional floating magnetic head.

[Explanation of symbols]

1, 9 ... Slider, 2, 3, 7, 10, 11 ... Air bearing surface,
4, 12 ... Magnetic head core, 5, 13 ... Gap, 6,
14 ... Adhesive, 8 ... Groove.

Claims (3)

[Claims] 1. A levitation type magnetic head having a plurality of grooves on an air bearing surface, wherein the grooves are composed of a groove substantially in a traveling direction of a slider and a groove intersecting the groove at 2 to 15 degrees. The magnetic head is a floating magnetic head. 2. The center line average roughness of the air bearing surface is 20 to 100.
The flying magnetic head according to claim 1, wherein the magnetic head is Å. 3. A floating magnetic head, wherein a plurality of grooves are formed only on a part of the floating surface.