Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
1999-06-30
2002-08-20
Kiliman, Leszek (Department: 1773)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S690000, C428S690000, C428S690000, C428S690000, C428S900000, C360S112000, C360S125020, C360S125330, C360S125330, C324S252000
Reexamination Certificate
active
06436560
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head of the type having a recording head and a reproducing head separately and used for a magnetic recording/reproducing device and a magnetic disc device using the magnetic head.
2. Description of the Related Art
One of the magnetic heads of the type having a recording head and a reproducing head separately is a magnetic head using a magnetoresistance effect element (hereinafter referred to as “MR element”). The MR element uses the characteristics that resistance changes in response to a change in the intensity of magnetic field and its reproducing output does not depend on the running speed of a magnetic recording medium, but depends only on the amount of magnetic flux of a magnetic signal. Therefore, the MR element can produce a sufficient reproducing output even if the running speed is low and hence has an advantage in increasing the recording density of a magnetic recording device and in reducing the size thereof.
The magnetic head of this kind is disclosed in IEEE Transaction on Magnetics, Vol. 26, page 1689, 1990, for example.
The magnetic head has increased the number of turns of coil in order to write by an intense magnetic field and to produce a large reproducing output and an insulating film for insulating the coil has been formed in multiple layers. Japanese Unexamined Patent Publication No. Hei 3-156714 discloses a technology for covering the whole multiple insulating films by the other insulating film in order to eliminate a level difference produced by the multiple insulating films.
On the other hand, in order to improve the areal recording density of magnetic recording, it will be necessary in the future to extensively increase a track density as well as a linear recording density. This requires that the track of a magnetoresistance effect head (hereinafter referred to as “MR head”) be formed in still narrower width and with higher accuracy.
The conventional magnetic head described above is not sufficient in the accuracy of a zero throat level position because it has the other insulating film covering the whole multiple insulating films for insulating the coil. In this connection, a throat level portion means a portion from the air bearing surface of a magnetic core to the tip end of interlayer insulating films for vertically separating an upper magnetic core from a lower magnetic core more than the thickness of a write gap. A zero throat level position means the tip end position of the insulating film nearest to the air bearing surface of the magnetic core among the interlayer insulating films.
On the other hand, the structure having no other insulating film covering the whole insulating films for insulating the coil has the following problem. The upper magnetic core is formed by a method comprising the steps of forming an underlying layer for plating on the insulating film for insulating the coil, forming a frame thereon by a photoresist, and electroplating the space thereof with a conductive film. However, when a frame pattern is formed, the light from a pattern exposure system is reflected by the underlying layer for plating at the level difference portion of the insulating film to produce halation. The photoresist of the unnecessary portion is exposed to the light. Therefore, for example, there exists a problem that a part of the magnetic core forming a track is not formed in a desired shape and that the accuracy of a track width is not sufficient.
Next, the conventional magnetic head will be described with reference to drawings.
FIG. 1A
is a plan view of an upper magnetic core and
FIG. 1B
is a cross sectional view showing a part of the magnetic head. In
FIG. 1B
, a first layer insulating film
7
is formed on a write gap film
20
and a second layer insulating film
9
a
for protecting a coil
8
is formed thereon and a third layer insulating film
9
b
for protecting the coil
8
is formed thereon and further an upper magnetic core
10
is formed thereon via an underlying layer
25
for plating.
The upper magnetic core
10
is formed by the use of a pattern formed from a positive photoresist (not shown) on the underlying layer
25
for plating formed on the third layer insulating film
9
b
formed on the second layer insulating film
9
a
formed on the first layer insulating film
7
.
As shown in
FIG. 1A
, if the position Pa where the upper magnetic core
10
spreads is located on the level difference portion of the second layer insulating film
9
a
or to the right hand side in the drawing, that is, in the direction away from the air bearing surface
36
, a depression is produced in the side of the resist pattern of the track portion
10
a
(in
FIG. 1A
, a left portion from the position Pa where the upper magnetic core spreads) by the reflecting light from the underlying film
25
for plating to produce a spreading portion
10
b
at the track portion
10
a
of the upper magnetic core
10
, when the photoresist is exposed to the light.
In the structure like this, since the portion where the magnetic flux of the upper track is to be contracted is expanded, the magnetic characteristics deteriorate. Further, when the air bearing surface is formed, if the track portion corresponding to the air bearing surface is expanded, there are produced variations in the width of the track of the air bearing surface
36
.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a magnetic head having good magnetic characteristics and improved accuracy in the width of a track on an air bearing surface.
It is another object of the present invention to provide a magnetic disc device using the magnetic head like this.
In order to achieve the object, the magnetic head in accordance with the present invention comprises a magnetoresistance effect type head for reproducing and an induction type head for recording and has two or more interlayer insulating films vertically separating an upper magnetic core from a lower magnetic core more than the thickness of a write gap. The position where the upper magnetic core spreads from a track portion is located nearer to an air bearing surface than the tip end position nearest to the air bearing surface among the tip end positions of the insulating films which are formed on the insulating film determining the zero throat level position and have level differences to each other.
If the insulating film which is formed on the insulating film determining the zero throat level position and has a level difference is one layer, it is essential only that the position where the upper magnetic core spreads from the track portion is located in front of (to the air bearing surface side of) the tip end position, that is, the tip position of the level difference, of the insulating film. If two or more insulating films with a level difference to each other are arranged, it is required only that the position where the upper magnetic core spreads from the track portion should be located in front of the tip end position of the insulating film whose tip end position is nearest to the air bearing surface.
The position where the upper magnetic core spreads may be located on the insulating film determining the zero throat level or nearer to the air bearing surface side, that is, directly on the write gap film. However, it is desirable that it is located about 0.5 &mgr;m or more behind the air bearing surface, that is, to the zero throat level side.
Further, in order to achieve the second object of the present invention, the magnetic disc device in accordance with the present invention comprises a rotatable magnetic recording medium having an information recording layer, a drive motor for rotating the magnetic recording medium at high speeds, a control means for controlling the rotation of the drive motor, a magnetic head provided with an electromagnetic converter for writing or reading information into or from the recording layer and movable on the recording layer of the magnetic recording medium. The magnetic head is used as this magnet
Kaneyama Koji
Kato Atsushi
Shiraki Kiyonori
Hitachi , Ltd.
Kiliman Leszek
Mattingly Stanger & Malur, P.C.
LandOfFree
Magnetic head and magnetic disk device using the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic head and magnetic disk device using the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic head and magnetic disk device using the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2962452