Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-10-04
2004-02-24
Ometz, David L. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06697219
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording thin film magnetic head used with, for example, a flying magnetic head and, more particularly, to a thin film magnetic head adapted to reduce inductance and capable of handling higher recording frequencies, and a manufacturing method for the same.
2. Description of the Related Art
FIG. 27
is a partial front view showing a construction of a conventional thin film magnetic head or inductive head, and
FIG. 28
is a partial sectional view of the thin film magnetic head cut along the line XXVIII—XXVIII shown in FIG.
27
and viewed from the direction of an arrow.
Reference numeral
1
shown in
FIGS. 27 and 28
denotes a lower core layer formed of a magnetic material, such as Permalloy. An insulating layer
9
is deposited on the lower core layer
1
.
The insulating layer
9
includes a groove
9
a
having an inner width represented by a track width Tw, the groove
9
a
extending in a height direction or Y direction in the drawing, from a surface facing a recording medium (hereinafter referred to as “ABS” which stands for air bearing surface).
In the groove
9
a
, a lower magnetic pole layer
3
magnetically connected to the lower core layer
1
, a gap layer
46
, and an upper magnetic pole layer
5
magnetically connected to an upper core layer
48
are deposited by sequentially plating in this order from bottom.
Referring to
FIG. 28
, a spirally formed coil layer
7
is provided on the insulating layer
9
in a portion in the height direction or the Y direction in the drawing from the groove
9
a
formed in the insulating layer
9
.
The coil layer
7
is covered by a coil insulating layer
47
formed of a resist or the like, and an upper core layer
48
is deposited on the coil insulating layer
47
. The upper core layer
48
is magnetically connected with the upper magnetic pole layer
5
at a distal end portion
48
a
and also magnetically connected to the lower core layer
1
at a proximal end portion
48
b.
In the inductive head shown in
FIGS. 27 and 28
, when recording current is supplied to the coil layer
7
, a recording field is induced in the lower core layer
1
and the upper core layer
48
. Magnetic signals are recorded in a recording medium, such as a hard disc, by a leakage field from between the lower magnetic pole layer
3
magnetically connected to the lower core layer
1
and the upper magnetic pole layer
5
magnetically connected to the upper core layer
48
.
In the inductive head shown in
FIGS. 27 and 28
, a lower magnetic pole layer
3
locally formed over the track width Tw, the gap layer
46
, and the upper magnetic pole layer
5
are provided in the vicinity of the surface facing the recording medium. This type of inductive head permits a narrower track.
The following will describe a manufacturing method for the inductive head shown in
FIGS. 27 and 28
. First, the insulating layer
9
is deposited on the lower core layer
1
, then the groove
9
a
having the track width Tw is formed in the insulating layer
9
for a predetermined length in the height direction (depth direction) from the surface facing the recording medium (air bearing surface).
In the groove
9
a
, the lower magnetic pole layer
3
, the gap layer
46
, and the upper magnetic pole layer
5
are continuously plated, then the coil layer
7
is pattern-deposited on a portion of the insulating layer
9
that is located behind (in the height direction) from the groove
9
a
formed in the insulating layer
9
.
The coil layer
7
is covered by a coil insulating layer
47
, and the upper core layer
48
is formed from the top of the upper magnetic pole layer
5
to cover the coil insulating layer
47
by the flame plating process. This completes the inductive head shown in
FIGS. 27 and 28
.
For a trend toward higher recording densities and higher recording frequencies, it is necessary to reduce a track width and the inductance of an inductive head.
In order to reduce inductance, a magnetic path formed via the upper core layer
48
from the lower core layer
1
must be made shorter. This requires that a width T
1
of the coil layer
7
formed from the distal end portion
48
a
to the proximal end portion
48
b of the upper core layer
48
be reduced. Reducing the width T
1
of the coil layer
7
allows the upper core layer
48
to be shortened so as to achieve a shorter magnetic path.
A method for forming the coil layer
7
by two layers could be applied to decrease the width T
1
of the coil layer
7
without changing the number of turns of the coil layer
7
.
In the construction of the thin film magnetic head shown in
FIGS. 27 and 28
, however, the magnetic path cannot be made sufficiently shorter to be able to handle higher recording frequencies in the future merely by providing the coil layer
7
with the double-layer construction. This makes it difficult to achieve an appropriate reduction in inductance.
A reason for the difficulty mentioned above is that the coil layer
7
is deposited on the insulating layer
9
having a thick film. Referring to
FIG. 27
, the insulating layer
9
has a film thickness H
5
, and the film thickness H
5
is larger than or substantially identical to a total film thickness H
6
of the lower magnetic pole layer
3
, the gap layer
46
, and the upper magnetic pole layer
5
. Therefore, as shown in
FIG. 28
, when a junction surface between the upper magnetic pole layer
5
and the upper core layer
48
is defined as a reference plane, the coil layer
7
deposited on the insulating layer
9
is positioned more closely to the upper core layer
48
than the reference plane.
Hence, adopting the double-layer construction directly to the coil layer
7
would lead to an extremely large height from the upper surface of the lower core layer
1
to the upper surface of the coil insulating layer
47
covering the coil layer
7
even though the width T
1
of the coil layer
7
can be reduced. As a result, the magnetic path cannot be shortened much, making it impossible to accomplish an appropriate reduction in inductance.
If the double-layer construction is simply applied to the coil layer
7
in the inductive head having the construction illustrated in
FIG. 28
, then a thickness H
1
of the coil insulating layer
47
covering the coil layer
7
increases, resulting in an extremely large bulge of the coil insulating layer
47
when the upper surface of the upper magnetic pole layer
5
is defined as the reference plane.
Accordingly, it becomes difficult to pattern-form the upper core layer
48
from above the upper magnetic pole layer
5
to cover the coil insulating layer
47
by the flame plating process, posing a problem in that a portion in the vicinity of the distal end portion
48
a
of the upper core layer
48
cannot be formed into a predetermined shape.
If the width T
2
of each conductor of the coil layer
7
is decreased, and a height H
2
of each conductor is increased, then there should be no change in the volume of the coil layer, thus avoiding an increase in a coil resistance value. Furthermore, in this case, since the width T
2
of each conductor can be reduced, the width T
1
of the entire coil layer
7
can be reduced, permitting a further reduction in inductance by making a magnetic path even shorter.
On the other hand, however, another problem arises in that the increased height H
2
of each conductor inevitably leads to an even larger bulge of the coil insulating layer
47
covering the coil layer
7
, preventing the upper core layer
48
from being formed with high accuracy.
SUMMARY OF THE INVENTION
The present invention has been made with a view toward solving the problems, and it is an object of the present invention to provide a thin film magnetic head that permits a narrower track and reduced inductance by making a magnetic path shorter, and a manufacturing method for the same.
According to one aspect of the present invention, there is provided a thin film magnetic head comprising: a lower core layer; an upper core layer; and a recording porti
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Ometz David L.
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