Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2002-12-17
2004-02-10
Ometz, David L. (Department: 2653)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S236700
Reexamination Certificate
active
06690544
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a magnetic disk apparatus and manufacturing techniques therefor and in particular to a method of manufacturing a low flying height thin-film magnetic head having non-linear rails as well as the shape/structure of a magnetic head slider. More particularly, the present invention is concerned with a processing method of removing particulates re-deposited during a dry-etching process of ceramics and the like of a low etching rate and hence a thin-film magnetic head suited for ensuring stably a low flying height while preventing head crash and a method of manufacturing the same.
BACKGROUND ART
Recording density of the magnetic disk apparatus increases rapidly from year to year, which in turn brings about necessarily a demand for reduction in the flying height of the magnetic head.
FIG. 10
is a view for illustrating a flying state of a magnetic head, wherein magnetic head
1
includes a floating surface
2
, a tapered portion
4
, a magnetic element
5
, an air-stream entraps end
7
and an air-stream exit end
8
and is supported by a leaf spring
10
. The floating surface
2
is formed with rails
3
. When a magnetic disk is not rotated, the magnetic head
1
and the magnetic disk
11
are placed in the state where they are in contact with each other. When a rotation speed of the magnetic disk has attained a predetermined value, an air bearing slider mechanism is formed by an air stream
40
entering from the air-stream entrance end
7
, flowing along the rails
3
and leaving the head from the air-stream exit end
8
, whereby a floating force is generated and thus the flying height
12
is determined by coaction of a push-down force exerted by the leaf spring
10
an the floating force. It is one of the important problems to decrease not only the flying height
12
but also variation or difference in the flying height ascribable to difference between the peripheral velocities of inner and outer peripheries of the magnetic disk.
FIG. 11
is a view showing a conventional magnetic head slider known heretofore and a processing method for the same. The conventional magnetic head slider is provided with linear rails
3
which are formed heretofore by a machining process carried out by using a grinding wheel
27
.
FIG. 14
shows relations between the peripheral velocity and the flying height. In the case where the linear rails are employed, the flying height is within a range of ca. 140 to 200 nm when the disk is operated at the peripheral velocity ranging from 15 to 35 m/s, wherein difference of the flying height between the inner and outer peripheries of the disk amounts to ca. 60 nm, which means that the flying height has a great dependency on the peripheral velocities. Furthermore, in the case where the linear rails are employed, the width of the rail and the flying height bear a proportional relation to each other, and it is desirable to decrease the rail width in order to reduce the flying height. However, in the portion at which the magnetic elements
5
are formed, as can be seen in
FIG. 11
, the rail width needs to accommodate the width of the magnetic element
5
. Consequently, limitation is necessarily imposed onto the diminution of the rail width.
Such being the circumstances, an inclined surface referred to as the chamfered portion is formed at each of corner portions of the rails
3
along which the aforementioned air stream flows in an effort to realize reduction of the flying height as well as suppression of the variation thereof, as is disclosed in U.S. Pat. No. 4,673,996. The inclined surface is so implemented that the angle formed relative to the floating surface is from 0.5 degree to 2 degrees and that the ratio of the area occupied by the chamfered portion to the area of the rail is from 12.5 to 22.5%. As an example of the chamfered portion, there can be mentioned one having a width on the order of 10 &mgr;m and a height of 2 &mgr;m.
Furthermore, by decreasing the width of a portion of the rail
3
, reduction of the flying height as well as suppression of the variation thereof is realized, as is disclosed in Japanese Unexamined Patent Application Publication No. 103406/1988. Additionally, by providing at a corner portion of the rail
3
along which the air stream flows an inclined surface having a width increasing gradually from the entrance end toward the exit end, reduction of the flying height as well as suppression of the variation thereof is realized, as is disclosed in Japanese Unexamined Patent Application Publication No. 188479/1992. By providing the chamfered portion in this manner, the flying height can be reduced so as to fall within a range of ca. 80 to 120 nm at the peripheral velocity of 15 to 35 m/s and at the same time the variation or difference in the flying height between the inner and outer peripheries of the disk is suppressed to ca. 40 nm.
In recent years, as the most effective means for reducing the flying height, there are increasingly adopted a method of using the rails of non-linear shape, as is disclosed in Japanese Unexamined Patent Application Publication No. 276367/1992. An example of the magnetic head having the non-linear rails is shown in FIG.
12
. In the case where the non-linear rails of this type are employed, the flying height can be suppressed to a low level within a range of ca. 60 to 75 nm when the disk is operated at the peripheral velocity ranging from 15 to 35 m/s, wherein difference of the flying height between the inner and outer peripheries of the disk is reduced to ca. 15 nm, as can be seen in FIG.
14
. The rails of the non-linear shape can ensure the flying height reducing effect equivalent to or more than that attained by the structure in which the chamfered portion is formed in the linear rail, as described above, and is very effective particularly for suppressing the variation of the flying height ascribable to the difference in the peripheral velocity between the inner and outer peripheries of the disk. Accordingly, by forming the chamfered portion in the rail of the non-linear shape which by itself exhibits the desired effect equivalent to or more than the linear rail provided with the chamfered portion, it is expected that the floating characteristic can further be enhanced. Thus, in view of the flying height and the excellent stability as realized, it is necessarily required to distinguish strictly the rail of the linear shape provided with the chamfered portion and the rail of the non-linear shape provided with the chamfered portion from each other. In the current state of the art, the structure in which the rail of the non-linear shape is provided with the chamfered portion is not known. By employing the rail of the non-linear shape, there can be achieved sufficiently the effects of reducing the flying height and suppressing the variation of the flying height, and it is expected that the floating characteristic can further be improved by providing a minute chamfered portion, which in turn however means that realization of optimal geometry of the chamfered portion requires fine and high-precision process when compared with the head having the rails of the linear shape.
In addition to the floating characteristic improving effect described above, provision of the chamfered portion can provide the additional effects mentioned below, as disclosed in Japanese Unexamined Patent Application Publication No. 9656/1985. As can be seen in
FIG. 10
, the flying height at the air-stream exit end
8
is small when compared with the flying height at the airstream entrance end
7
, and thus the air-stream exit end
8
is more likely to contact the magnetic disk
11
. For this reason, it is desired that the geometry of the air-stream exit end
8
of the magnetic head
1
be smooth for protecting not only the magnetic disk
11
but also the magnetic head itself against injury. To this end, the chamfered portion is provided. In order to realize the effects mentioned above with the rails of the non-linear shape, there-is demanded realization of the non-linear rails strictly w
Agari Hiroshi
Akamatsu Kiyoshi
Chiba Hiromu
Fujisawa Masayasu
Hira Yasuo
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