Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-08-04
2003-02-04
Heinz, A. J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06515825
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin film magnetic recording head used for, for example, a floating magnetic head. More particularly, the present invention relates to a thin film magnetic head intended to decrease inductance to be made adaptable to higher recording frequencies, and a method of manufacturing the same.
2. Description of the Related Art
FIG. 18
is a partial front view showing the structure of a conventional thin film magnetic head (inductive head).
FIG. 19
is a partial sectional view of the thin film magnetic head shown in
FIG. 18
taken along line XIX—XIX, as viewed from the direction of arrows.
In
FIGS. 18 and 19
, the bottom core layer
1
is made of a magnetic material such as permalloy or the like. An insulating layer
9
is formed on the bottom core layer
1
. The insulating layer
9
has a trench
9
a
which is formed in the height direction (the Y direction shown in
FIG. 18
) from the air bearing surface (referred to as “ABS” hereinafter) facing a recording medium to have an inner width dimension equal to the track width Tw.
Also, a bottom pole layer
3
magnetically connected to the bottom core layer
1
, a gap layer
4
and a top pole layer
5
magnetically connected to a top core layer
6
are formed in the trench
9
a
by plating in turn from the bottom.
As shown in
FIG. 19
, a coil layer
7
patterned in a spiral shape is provided on the portion of the insulating layer
9
, which is located at the back of the trench
9
a
formed in the insulating layer
9
in the height direction (the Y direction shown in FIG.
19
).
The coil layer
7
is covered with an organic insulating layer
8
of resist or the like. The top core layer
6
is formed on the organic insulating layer
8
. The front end
6
a
of the top core layer
6
is magnetically connected to the top pole layer
5
. The base end
6
b
is magnetically connected to the bottom core layer
1
.
In the inductive head shown in
FIGS. 18 and 19
, when a recording current is supplied to the coil layer
7
, a recording magnetic field is induced in each of the top and bottom core layers
1
and
6
. A magnetic signal is recorded on a recording medium such as a hard disk by a leakage magnetic field between the bottom pole layer
3
and the top pole layer
5
magnetically connected to the bottom core layer
1
and the top core layer
6
, respectively.
In the inductive head shown in
FIGS. 18 and 19
, the bottom pole layer
3
, the gap layer
4
and the top pole layer
5
are locally formed with the track width Tw near the ABS (the surface facing the recording medium). This type of inductive head is adaptable to narrower tracks.
The method of manufacturing the inductive head shown in
FIGS. 18 and 19
is described below. First, the insulating layer
9
is formed on the bottom core layer
1
. The trench
9
a
having the track width Tw is formed in the insulating layer
9
with a predetermined length from the ABS in the height direction.
Next, the bottom pole layer
3
, the gap layer
4
and the top pole layer
5
are continuously formed by plating in the trench
9
a
. The coil layer
7
is patterned on the portion of the insulating layer
9
, which is located at the back of the trench
9
a
formed in the insulating layer
9
.
Furthermore, the coil layer
7
is covered with the organic insulating layer
8
. The top core layer
6
is formed by frame plating to extend from the top pole layer
5
to the organic insulating layer
8
to complete the inductive head shown in
FIGS. 18 and 19
.
It is necessary to decrease the inductance of the inductive head with track narrowing accompanying increases in recording density and recording frequency in future. In order to decrease the inductance, the magnetic path formed from the bottom core layer
1
to the top core layer
6
must be shortened. Thus, the width dimension T
1
of the coil layer
7
formed between the front end
6
a
and the base end
6
b
of the top core layer
6
must be decreased. By decreasing the width dimension T
1
of the coil layer
7
, the length of the top core layer
6
can be shortened to realize a short magnetic path.
A possible method of decreasing the width dimension T
1
of the coil layer
7
without changing the number of the turns of the coil layer
7
is one in which the coil layer
7
is formed in a laminated structure comprising two layers.
However, in the structure of the thin film magnetic head shown in
FIGS. 18 and 19
, even when the coil layer
7
has a simple two-layer laminated structure, the magnetic path cannot be shortened so that it is made adaptable to higher recording frequency in future, thereby causing difficulties in appropriately decreasing inductance.
This is because the coil layer
7
is formed on the thick insulating layer
9
. As shown in
FIG. 18
, the insulating layer
9
has a thickness H
5
which is more than the total thickness H
6
of the bottom pole layer
3
, the gap layer
4
and the top pole layer
5
. Therefore, assuming that the surface of the top pole layer
5
is a reference plane, the coil layer
7
is formed on the insulating layer
9
nearer the top core layer
6
than the reference plane, as shown in FIG.
19
.
Therefore, with the coil layer
7
having a two-layer laminated structure, the width dimension T
1
of the coil layer
7
can be decreased, but the height from the top of the bottom core layer
1
to the top of the insulating layer
8
formed to cover the coil layer
7
is substantially increased. As a result, the magnetic path cannot be much shortened, and the inductance cannot be appropriately decreased.
In the inductive head having the structure shown in
FIG. 19
, with the coil layer
7
having two-layer laminated structure, the thickness dimension H
1
of the organic insulating layer
8
formed to cover the coil layer
7
is increased. Thus, the organic insulating layer
8
significantly rises from the surface of the top pole layer
5
as the reference plane.
Therefore, the top core layer
6
cannot be easily formed by frame plating to extend from the top pole layer
5
to the organic insulating layer
8
, thereby causing the problem of making it impossible to form the top core layer
6
, particularly the portion near the front end
6
a
thereof, in a predetermined shape.
SUMMARY OF THE INVENTION
The present invention has been achieved for solving the above problems. An object of the invention is to provide a thin film magnetic head in which the magnetic path can be shortened to decrease inductance, and a method of manufacturing the thin film magnetic head.
A thin film magnetic head of the present invention comprises a bottom core layer, a top core layer, and a track width control portion located between the bottom and top core layers on the surface facing a recording medium and having a controlled dimension in the direction of the track width. The track width control portion comprises a gap layer magnetically insulating at least one of the bottom and top pole layers connected to the bottom and top core layers, respectively, from each of the pole layers, or one of the core layers from the corresponding one of the pole layers. When the junction surface between the track width control portion and the top core layer is the reference plane, a coil layer for inducing a recording magnetic field in the bottom and top core layers is located at the back of the track width control portion in the height direction. The upper surface of the coil layer is located nearer the bottom core layer than the reference plane. Furthermore, an insulating layer is provided between the reference plane and the bottom core layer. The coil layer is buried in the insulating layer. The top core layer is formed to extend from the track width control portion to the insulating layer so that the base end of the top core layer is magnetically connected to the bottom core layer.
In the present invention, in order to manufacture the thin the thin film magnetic head adaptable to future increases in recording density and recording frequency, particularly, the form
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