Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-09-13
2003-01-07
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06504687
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to thin-film magnetic heads, and more particularly, relates to a thin-film magnetic head having improved abrasion-resistance in a face opposing a recording medium.
2. Description of the Related Art
Since thin-film magnetic heads having magnetoresistive devices can better meet the need for the further narrowing of tracks compared with conventional bulk-type magnetic heads, thin-film magnetic heads in various forms have been applied to sliding-type magnetic heads which slide relative to a tape medium having high writing density and to floating-type magnetic heads which move relative to a magnetic disk without contacting therewith.
A sliding-type magnetic head having a conventional thin-film magnetic head will be described with reference to the figures.
FIG. 15
is a perspective view of a conventional sliding-type magnetic head,
FIG. 16
is a plan view of a major portion of the sliding-type magnetic head observed from an opposing face opposing a recording medium side, and
FIG. 17
is a cross-sectional view taken along the line XVII—XVII in FIG.
16
.
A sliding-type magnetic head B shown in
FIG. 15
is formed in an overall block shape, in which half-cores (substrates)
202
and
203
in the form of blocks are adhered to each other at side edge surfaces thereof with an in-core layer
5
therebetween. One side surface of a block formed of the half-cores
202
and
203
is fixed on a mounting plate
201
by adhesive so that a small portion of the block formed of the half-cores
202
and
203
protrudes out from the edge of the mounting plate
201
.
One surface of the sliding-type magnetic head B protruding out from the mounting plate
201
is processed so as to have a curved convex shape, and the surface having the curved convex shape is used as a sliding face
206
sliding on a magnetic recording medium such as a magnetic tape.
As shown in
FIGS. 16 and 17
, a writing head (hereinafter referred as to an inductive head)
210
for writing and a thin-film magnetic head
211
for reading, provided with a magnetoresistive device, are embedded in the in-core layer
205
.
The thin-film magnetic head
211
is composed of a lower shield layer
101
, a lower insulating layer
104
, a magnetoresistive device (hereinafter referred to as an MR device)
105
, an upper insulating layer
106
, and an upper shield layer
107
, which are sequentially formed on the half-core
202
.
As shown in
FIG. 16
, the edge faces of the lower shield layer
101
, the lower insulating layer
104
, the MR device
105
, the upper insulating layer
106
, and the upper shield layer
107
are exposed at the sliding face
206
sliding on a magnetic recording medium.
A reading magnetic gap G is formed by the lower insulating layer
104
and the upper insulating layer
106
.
The upper shield layer
107
and the lower shield layer
101
are composed of, for example, a nickel-iron (NiFe) alloy; the upper shield layer
107
is formed by plating, and the lower shield layer
101
is formed by sputtering.
In addition, the upper insulating layer
106
and the lower insulating layer
104
are composed of, for example, Al
2
O
3
, and are formed by sputtering.
In the structure shown in
FIGS. 16 and 17
, the upper shield layer
107
is also used as a lower core layer for the inductive head
210
formed on the upper shield layer
107
, a writing gap layer
110
is formed on the lower core layer (the upper shield layer)
107
, a coil layer
111
patterned so as to be planar and spiral is formed on the writing gap layer
110
, the coil layer
111
is surrounded with a coil insulating layer
112
, and a front portion
113
a
of an upper core layer
113
formed on the coil insulating layer
112
opposes the lower core layer
107
at a minute distance therefrom with the writing gap layer
110
therebetween at the sliding face
206
. A base portion side
113
b
of the upper core layer
113
is magnetically coupled with the lower core layer
107
. In addition, a protective layer
116
is formed over the upper core layer
113
. Numeral reference
108
in
FIG. 17
indicates electrodes for detection connected to the MR device
105
, and the electrodes
108
are connected to both sides of the MR device
105
.
The sliding-type magnetic head B is produced by, for example, the steps as described below. The in-core layer
205
is first formed by sequentially forming the thin-film magnetic head
211
and the inductive head
210
by a thin-film formation technique on the half-core
202
, and the other half-core
203
is then adhered to the in-core layer
205
so as to form the core block. Subsequently, one surface of the core block is polished by a polishing tape having a polishing powder composed of diamond or the like dispersed thereon so as to form the sliding face
206
having a curved convex shape, whereby the sliding-type magnetic head B is obtained.
However, in the sliding-type magnetic head B, since the upper and the lower shield layers
107
and
101
, which sandwich the upper and lower insulating layers
106
and
104
, are formed of a NiFe alloy having relatively low hardness, when the core block is polished by the polishing tape, the surfaces of the upper and the lower shield layers
107
and
101
, which are polished, may be stretched, and as a result, sags D in the form of a tongue may be formed as shown in FIG.
16
. In some cases, the sags D in the form of a tongue may extend from, for example, the upper shield layer
107
to the MR device
105
or the lower shield layer
101
, and hence, there is a problems in that short-circuiting between the upper and the lower shield layers
107
and
101
and the MR device
105
may occur.
In addition, when the sliding-type magnetic head B slides relative to a magnetic tape or the like in order to read the magnetic writing information, the sliding face
206
of the head is actually polished by the magnetic tape, and in a manner similar to that described above, the shield layers
107
and
101
may be stretched so as to form the sags D.
Furthermore, recently, in order to respond to the need for higher magnetic writing density, the distance between the upper and the lower shield layers
107
and
101
, i.e., the magnetic gap G, must be reduced. Accordingly, the upper and the lower insulating layers
106
and
104
tend to be thinner, and in this case, even when smaller sags are formed, the shield layers
107
and
101
are readily brought into contact with each other, whereby there is a problem in that short-circuiting is more likely to occur.
SUMMARY OF THE INVENTION
Taking the problems described above into consideration, an object of the present invention is to provide a thin-film magnetic head having a structure which prevents short-circuiting, in which, even if sags in a shield layer are formed when a sliding face sliding relative to a recording medium is polished, the sags do not reach an MR device or another shield layer.
To these ends, the present invention employs the following structure.
A thin-film magnetic head according to the present invention comprises a laminate comprising a magnetoresistive device for reading information by moving relative to a magnetic recording medium, insulating layers provided on both sides of the magnetoresistive device in the thickness direction thereof, and shield layers provided on each insulating layer, and a substrate on which the laminate is provided, in which the magnetoresistive device, the insulating layers, and the shield layers are exposed at an opposing face opposing a recording medium, wherein at least one of the shield layers in contact with the insulating layers comprises a magnetic layer and a rigid layer which is harder than the magnetic layer and is in contact with the insulating layer.
In the thin-film magnetic head described above, since at least one of the two shield layers with the magnetoresistive device provided therebetween is composed of a magnetic layer and a rigid layer, and since it is exposed at the opposing face opposing a recording medium, t
Miyatake Akira
Umetsu Eiji
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Evans Jefferson
LandOfFree
Thin-film magnetic head having abrasion-resistant face... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thin-film magnetic head having abrasion-resistant face..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin-film magnetic head having abrasion-resistant face... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3058114