Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
1999-12-28
2003-01-07
Hudspeth, David (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06504677
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to a high data rate magnetic write head and more particularly to a multi-layer stitched magnetic write head design.
(2) Description of the Related Art
Magnetic read heads, often referred to as inductive read heads, must be designed in such a way that the magnetic flux extends across the air bearing surface into the magnetic media as much as possible. A cross section view of a conventional magnetic read/write head is shown in FIG.
1
. As shown in
FIG. 1
a magnetic sensor
16
is placed adjacent to the air bearing surface
30
of the head between a first ferromagnetic shield
10
and a second ferromagnetic shield
18
ferromagnetic shield.
The second ferromagnetic shield
18
also serves as the first pole piece
18
for the write portion of the head. A first non-magnetic gap layer
20
is formed on the first pole piece
18
and determines the gap
12
between the first pole piece
18
and the second pole piece
26
at the plane of the air bearing surface (ABS)
30
. A second non-magnetic gap layer
22
is formed on the first non-magnetic gap layer
20
beginning a first distance
32
away from the ABS plane
30
. The beginning of the second non-magnetic gap layer
22
defines the point where the gap
12
between the first pole piece
18
and the second pole piece
26
begins to widen. A layer of wiring
28
, imbedded in a layer of insulating material
24
, is formed on the second non-magnetic gap layer
20
. An additional insulation layer
25
may be used to provide a smoother surface on which to form the second pole piece
26
. The second pole piece is formed over the first non-magnetic gap layer, the second non-magnetic gap layer, and the additional insulation layer
25
. It is advantageous to have the first distance
32
as small as possible in order to have the optimum distribution of magnetic flux.
U.S. Pat. No. 5,805,391 to Chang et al. describes a write head with a recessed stitched yoke on a planar portion of an insulation layer defining the zero throat height, or the point where the gap between pole pieces begins to widen. A second pole piece if formed of two pole piece components stitched together, or placed in contact to reduce the non-magnetic gap between the two pole components to zero.
U.S. Pat. No. 5,802,700 to Chen et al. describes a method of making a planarized thin film magnetic write head with submicron trackwidth.
U.S. Pat. No. 5,878,481 to Feng et al. describes a pole trimming method of forming a magnetic transducer structure.
SUMMARY OF THE INVENTION
In the design of magnetic write heads for high track per inch or low trackwidth applications it is important to have the throat height as small as possible. The throat height is the distance from the ABS end of the poles to point where the non-magnetic gap between the poles begins to widen, reference number
32
in
FIG. 1. A
stitched pole design can be used to improve the throat height but it is also necessary to have a recessed yoke design. The recessed yoke design provides a separation between the second pole piece, reference number
26
in
FIG. 1
, and the air bearing surface at the point where the second pole piece curves to provide an increased non-magnetic gap width.
It is a principle objective of this invention to provide a magnetic write head having multi-layer stitched poles, a small throat height, a recessed yoke design, and a planar top surface.
It is another principle objective of this invention to provide a magnetic write head having multi-layer stitched poles, a small throat height, and a recessed yoke design.
These objectives are achieved by using a multi-layer stitched pole design. A non-magnetic gap layer is formed on a layer of ferromagnetic material. A first pole piece is then formed on the non-magnetic gap layer. A notch is formed in the first pole piece to define the throat height. A second pole piece, recessed from the first pole piece is then formed making contact with the first pole piece. A third pole piece, recessed from the second pole piece is formed making contact with the second pole piece. The first, second, and third pole pieces form a stitched pole since there are regions of zero non-magnetic gap between the first pole piece and the second pole piece and between the second pole piece and the third pole piece. The notch in the first pole piece defines the throat height, the recessed second and third pole pieces form a recessed yoke, and the structure can be made planar.
REFERENCES:
patent: 5245493 (1993-09-01), Kawabe et al.
patent: 5802700 (1998-09-01), Chen et al.
patent: 5805391 (1998-09-01), Chang et al.
patent: 5828533 (1998-10-01), Ohashi et al.
patent: 5878481 (1999-03-01), Feng et al.
patent: 6104576 (2000-08-01), Santini
patent: 6111724 (2000-08-01), Santini
patent: 6163436 (2000-12-01), Sasaki et al.
patent: 6191916 (2001-02-01), Sasaki
patent: 6204997 (2001-03-01), Sasaki
Chen Mao-Min
Han Cherng-Chyi
Ackerman Stephen B.
Castro Angel
Headway Technologies Inc.
Hudspeth David
Prescott Larry J.
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