Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-08-23
2003-10-21
Heinz, A. J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Core
C029S603160
Reexamination Certificate
active
06636381
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film magnetic recording head for use in, for example, a flying magnetic head, and more particularly, to a thin-film magnetic head which is capable of reducing the track width, preventing write fringing, and reducing magnetic saturation, and a production method for the head.
2. Description of the Related Art
FIG. 12
is a partial front view showing the structure of a conventional thin-film magnetic head (inductive head), and
FIG. 13
is a partial sectional view of the thin-film magnetic head, taken along line XIII—XIII in
FIG. 12
, as viewed from the directions of the arrows.
Referring to
FIGS. 12 and 13
, a lower core layer
1
is made of a magnetic material, such as permalloy, and a nonmagnetic gap layer
7
is formed thereon.
As shown in
FIG. 13
, a coil layer
5
is formed on the gap layer
7
via an organic insulating layer
4
made of a polyimide, a resist, or the like.
An organic insulating layer
6
made of a polyimide, a resist, or the like is formed on the coil layer
5
, and an upper core layer
3
made of a magnetic material, such as permalloy, is formed on the organic insulating layer
6
.
As shown in
FIG. 12
, a leading end portion
3
a
of the upper core layer
3
opposes the lower core layer
1
via the gap layer
7
, and the width thereof is limited to a track width Tw. A base end portion
3
b
of the upper core layer
3
is magnetically connected to the lower core layer
1
.
In the inductive head shown in
FIGS. 12 and 13
, when a recording current is applied to the coil layer
5
, a recording magnetic field is induced in the lower core layer
1
and the upper core layer
3
, and a magnetic signal is recorded on a recording medium, such as a hard disk, by a leakage magnetic field from between the leading end portion
3
a
of the upper core layer
3
and the lower core layer
1
.
With future increase in recording density, it is necessary to reduce the track width.
As described above, the track width Tw is regulated by the width of the leading end portion
3
a
of the upper core layer
3
(see FIG.
12
). The upper core layer
3
is formed by so-called flame plating.
In flame plating, a resist layer is first applied over the entire surface where the upper core layer
3
is to be formed, and a pattern of the upper core layer
3
is formed on the resist layer by exposure and development. Subsequently, the pattern is plated with a magnetic material, and the resist layer is removed, thereby finishing the upper core layer
3
having the shape shown in
FIGS. 12 and 13
.
The resolution of the resist layer is greatly concerned with the wavelength of the light used for exposure and development. The resolution can be improved by shortening the wavelength.
However, the resolution has, of course, its limits, and it is impossible to perform patterning when the track width Tw regulated by the width of the leading end portion
3
a
of the upper core layer
3
is smaller than the resolution limit. Accordingly, it is difficult for the inductive head with the structure shown in
FIGS. 12 and 13
to reduce the track width with future increase in recording density.
When the track width Tw is reduced, the volume of the leading end portion
3
a
of the upper core layer
3
is decreased, and magnetic saturation becomes pronounced with an increase in recording frequency. This degrades the recording characteristics.
In the inductive head shown in
FIGS. 12 and 13
, a leakage magnetic field produced between the lower core layer
1
and the leading end portion
3
a
of the upper core layer
3
protrudes from the track width Tw, that is, so-called write fringing is prone to occur.
When write fringing occurs, the track position on a recording medium cannot be detected precisely, an tracking servo error is caused, and the recording characteristics are degraded.
Write fringing is prone to be caused when the lower core layer
1
protrudes from the track width Tw, as shown in
FIG. 12
, and the distance between the protruding portion of the lower core layer
1
and the leading end portion
3
a
of the upper core layer
3
is short.
Japanese Unexamined Patent Application Publication No. 10-143817 discloses the structure of an inductive head which effectively prevents write fringing described above.
However, the invention disclosed in the above publication makes the production procedure troublesome. That is, the production procedure includes a process of removing the portion of the gap layer
7
protruding from the track width Tw shown in FIG.
12
. While an appropriate distance can be formed between the lower core layer
1
and the leading end portion
3
a
of the upper core layer
3
by etching the surface of the lower core layer
1
, which is exposed by removing the portion of the gap layer
7
, by ion milling, magnetic powders adhere to both side faces of the leading end portion
3
a
and the like. A process of removing the adhering powders is also required.
Furthermore, the disclosed invention does not allow reduction in track width and prevention of magnetic saturation.
SUMMARY OF THE INVENTION
The present invention solves to the above conventional problems, and an object of the present invention is to provide a thin-film magnetic head which is capable of reducing the track width, preventing write fringing, and reducing magnetic saturation, and a production method for the head.
According to an aspect of the present invention, there is provided a thin-film magnetic head including upper and lower core layers, and a track width regulating section disposed between the upper and lower core layers so as to have a width shorter than those of the upper and lower core layers, wherein the track width regulating section is composed of a lower pole layer connected to the lower core layer, an upper pole layer connected to the upper core layer, and a gap layer disposed between the lower pole layer and the upper pole layer, or is composed of an upper pole layer connected to the upper core layer and a gap layer disposed between the upper pole layer and the lower core layer, and an inclined face is formed on the upper surface of the lower core layer extending on both sides of the track width regulating section so as to be inclined away from the track width regulating section in the track width direction in order to gradually increase the distance from the upper core layer.
As described above, the track width regulating section, whose width in the track width direction is regulated by the track width, is formed between the upper, core layer and the lower core layer. The upper pole layer magnetically connected to the upper core layer is formed in the track width regulating section. Since the inclined face inclined in the direction away from the upper core layer is formed on the upper surface of the lower core layer extending from both sides of the track width regulating section, an appropriate distance is ensured between the upper pole layer and the lower core layer, and write fringing can be effectively prevented.
The width of the upper core layer formed on the upper pole layer is larger than the track width. This adequately reduces magnetic saturation adjacent to the leading end portion of the upper core layer.
In a production method which will be described later, the width of the track width regulating section (=the track width) can be made smaller than the resolution obtained by the wavelength of the light used for exposure and development of a resist, which allows the track width to be reduced with future increase in recording density.
Preferably, the track width to be regulated by the width of the track width regulating section is 0.4 &mgr;m or less. This value is smaller than the resolution obtained when the i-line is used during exposure and development of the resist. More preferably, the track width is set at 0.2 &mgr;m or less.
Preferably, an inclination angle &thgr;
1
of the inclined face formed on the upper surface of the lower core layer with respect to the track width direction ranges fro
Gochou Hideki
Kobayashi Kiyoshi
Koyama Akira
Sato Kiyoshi
Yamada Minoru
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Heinz A. J.
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