Dynamic magnetic information storage or retrieval – Head – Coil
Reexamination Certificate
2001-10-15
2004-04-13
Letscher, George J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Coil
C360S125330
Reexamination Certificate
active
06721130
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to thin-film magnetic heads that are used for magnetic recording of, for example, magnetic hard discs. In particular, the present invention relates to a thin-film magnetic head which meets requirements for high recording density and frequency, and a method for manufacturing the thin-film magnetic head.
2. Description of the Related Art
A known thin-film magnetic head is formed on a substantially rectangular slider
61
made of a nonmagnetic material, as shown in FIG.
1
. In
FIG. 20
, a recording head of the known thin-film magnetic head is formed such that first and second coil layers
59
and
60
, which have a laminated structure in two layers, are disposed between an upper core layer
56
and a lower core layer
57
opposing each other.
In
FIG. 20
, an upper magnetic-pole layer
63
and a lower magnetic-pole layer
51
sandwich a magnetic gap layer
62
, the upper magnetic-pole layer
63
and the lower magnetic-pole layer
51
being disposed at ends of the upper core layer
56
and the lower core layer
57
, respectively, and magnetically connected thereto.
The first coil layer
59
is disposed toward the lower core layer
57
from a reference plane S
5
, which is the interface where the upper magnetic layer
63
and the upper core layer
56
are joined to each other. The first coil layer
59
is covered with an insulation layer
64
of which a surface is disposed at the reference plane S
5
.
The second coil layer
60
is formed on the surface of the insulation layer
64
which is disposed at the reference plane S
5
.
Width and thickness of a coil conductor of the second coil layer
60
equal the width and thickness of the coil conductor of the first coil layer
59
, respectively.
A first organic insulation-layer
58
covers the second coil layer
60
and forms an inclined face
58
a
toward a magnetic-disc-opposing face
61
b
of the slider
61
. The inclined face
58
a
of the first organic insulation-layer
58
gradually separates from the magnetic-disc-opposing face
61
b
along the inclination in a film-thickness direction from the reference plane S
5
.
The upper core layer
56
covers the second coil layer
60
with the first organic insulation layer
58
therebetween. An end of the upper core layer
56
extends from the inclined face
58
a
of the first organic insulation layer
58
to an upper face of the upper magnetic-pole layer
63
.
The upper core layer
56
is formed, as shown in
FIG. 21
, such that a conductive primary coat
70
for plating is deposited by sputtering on the first organic insulation layer
58
, the primary coat
70
is coated with a resist
71
, and the resist
71
is formed by photolithography into a resist frame corresponding to the shape of the upper core layer
56
.
In an exposure step of photolithography for forming the resist frame, exposure light is irregularly reflected at the primary coat
70
deposited on the inclined face
58
a
of the first organic insulation layer
58
.
When an angle formed between the inclined face
58
a
of the first organic insulation-layer
58
and the reference plane S
5
is large, a major part of the irregularly reflected exposure light leaks toward the magnetic-disc-opposing face
61
b
, whereby there is a risk in that portions of the resist
71
which must be shielded are exposed.
When the angle formed between the inclined face
58
a
of the first organic insulation-layer
58
and the reference plane S
5
is large, the resist frame cannot be formed in a shape as it is designed, and it is difficult to form the upper core layer
56
correctly in desired position and shape.
When the angle formed between the inclined face
58
a
of the first organic insulation-layer
58
and the reference plane S
5
is large, the thickness of the first organic insulation-layer
58
is significantly reduced at corners at the outer and inner peripheries of the second coil layer
60
, whereby there is a risk of a short circuit between the second coil layer
60
and the upper core layer
56
. When the distance between the second coil layer
60
and the upper core layer
56
is increased without changing the shape of the second coil layer
60
in order to avoid short circuit between the second coil layer
60
and the upper core layer
56
, the length of a magnetic path in the upper core layer
56
is increased; therefore, it is difficult to cope with high-frequency recording.
In the known thin-film magnetic head, the thickness of a coil conductor of the first coil layer
59
equals the thickness of the coil conductor of the second coil layer
60
. Therefore, when the coil conductor of the second coil layer
60
is thick, the coil conductor of the first coil layer
59
becomes also thick. In this case, when the insulation layer
64
covering the first coil layer
59
is thin, there is a risk in that the first coil layer
59
is exposed from the insulation layer
64
, whereby there is a risk in that a short circuit occurs between the first coil layer
59
and the second coil layer
60
.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a reliable thin-film magnetic head.
The thin-film magnetic head of the present invention comprises a lower core layer; an upper core layer opposing the lower core layer; an upper magnetic-pole layer disposed between the upper core layer and the lower core layer and joined to the upper core layer; a magnetic gap layer disposed between the upper magnetic-pole layer and the lower core layer; a first coil layer disposed at the lower core layer side of an interface between the upper core layer and the upper magnetic-pole layer, which are joined to each other; and a second coil layer disposed at the upper core layer side of the interface. The thickness of a coil conductor of the first coil layer is smaller than the thickness of a coil conductor of the second coil layer.
With this arrangement, the first coil layer can be formed at a sufficiently large distance from the interface between the upper magnetic-pole layer and the upper core layer by reducing the thickness of the coil conductor of the first coil layer, whereby a reliable thin-film magnetic head is obtainable, in which insulation between the first and second coil layers is ensured. In the thin-film magnetic head according to the present invention, the interface between the upper magnetic-pole layer and the upper core layer can be lowered because the first coil layer is disposed at a sufficiently large distance from the interface, whereby the thickness of the upper magnetic-pole layer can be reduced. By reducing the thickness of the upper magnetic-pole layer, magnetic fluxes can flow efficiently from the upper core layer to the magnetic gap layer; therefore, the thin-film magnetic head can cope with high recording density.
The width of the coil conductor of the second coil layer may be smaller than the width of the coil conductor of the first coil layer.
By increasing the thickness and reducing the width of the coil conductor of the second coil layer, a proper number of windings can be provided in a reduced area without increasing DC resistance in the coil conductor. Therefore, the length of the upper core layer from a part of the second coil layer in the vicinity of a coil center thereof to the periphery of the second coil layer can be reduced, whereby the length of a magnetic path is reduced, thereby providing a thin-film magnetic head having low inductance and capable of high-frequency recording.
When the thickness of the first coil layer is reduced corresponding to the reduction of thickness of the upper magnetic-pole layer in accordance with requirements for high recording density, DC resistance in the first coil layer is maintained at a low level by increasing the width of the coil conductor of the first coil layer. Therefore, a thin-film magnetic head can be provided, in which power loss in the first coil layer is suppressed.
The distance between each winding of the coil conductor of the second coil layer may be smalle
Gochou Hideki
Kobayashi Kiyoshi
Takahashi Toru
Yazawa Hisayuki
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