Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
1999-05-26
2002-06-04
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06400526
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to magnetic data storage systems, more particularly to thin film read/write heads, and most particularly to a write element with an impedance tailored to be able to match the impedance of a shorten connector between a pre-amp chip and the write element, allowing for both higher data transfer rates and higher storage capacities.
Magnetic disk drives are used to store and retrieve data for digital electronic apparatuses such as computers. In
FIGS. 1A and 1B
, a magnetic disk data storage system
10
includes a sealed enclosure
12
, a disk drive motor
14
, and a magnetic disk, or media,
16
supported for rotation by a drive spindle S
1
of motor
14
. Also included are an actuator
18
and an arm
20
attached to an actuator spindle S
2
of actuator
18
. A suspension
22
is coupled at one end to the arm
20
, and at its other end to a read/write head or transducer
24
. The transducer
24
typically includes an inductive write element with a sensor read element (which will be described in greater detail with reference to FIG.
2
). As the motor
14
rotates the magnetic disk
16
, as indicated by the arrow R, an air bearing is formed under the transducer
24
causing it to lift slightly off of the surface of the magnetic disk
16
, or, as it is sometimes termed in the art, to “fly” above the magnetic disk
16
. Data bits can be written to and read from a magnetic “track” as the magnetic disk
16
rotates. Also, information from various tracks can be read from the magnetic disk
16
as the actuator
18
causes the transducer
24
to pivot in an arc as indicated by the arrows P. The width of a track is sometimes called the “trackwidth.” Narrower trackwidths allow a greater number of tracks to be placed on a magnetic disk
16
, thereby increasing its total storage capacity. The design and manufacture of magnetic disk data storage systems is well known to those skilled in the art.
FIG. 2
depicts a magnetic read/write head
24
of the prior art including a read element
26
and a write element
28
. Surfaces of the read element
26
and write element
28
also define a portion of an air bearing surface ABS, in a plane
29
, which can be aligned to face the surface of the magnetic disk
16
(see FIGS.
1
A and
1
B). The read element
26
includes a first shield
30
, an intermediate layer
32
, which functions as a second shield, and a read sensor
34
that is located within a dielectric medium
35
between the first shield
30
and the second shield
32
. The most common type of read sensor
34
used in the read/write head
24
is the magnetoresistive (AMR or GMR) sensor which is used to detect magnetic field signals from a magnetic medium through changing resistance in the read sensor.
The write element
28
is typically an inductive write element which includes a first pole
38
and the intermediate layer
32
, which functions as a second pole. A second pole pedestal
42
is connected to a second pole tip portion
45
of the second pole. The first pole
38
and the second pole
32
are attached to each other by a backgap portion
40
, with these three elements collectively forming a yoke
41
with the second pole pedestal
42
. The area around the first pole tip portion
43
and a second pole tip portion
45
near the ABS is sometimes referred to as the yoke tip region
46
. A write gap
36
is formed between the first pole
38
and the second pole pedestal
42
in the yoke tip region
46
, and is formed from a non-magnetic electrically insulating material. This non-magnetic material can be either integral with or separate from (as shown here) a first insulation layer
47
that lies between the first pole
38
and the second pole
32
, and extends from the yoke tip region
46
to the backgap portion
40
.
Also included in write element
28
is a conductive coil layer
48
, formed of multiple winds
49
. The conductive coil
48
is positioned within a coil insulation layer
50
that lies below the first pole
38
. The coil insulation layer
50
thereby electrically insulates the coil layer
48
from the first pole
38
and insulates the multiple winds
49
from each other, while the first insulation layer
47
electrically insulates the winds
49
from the second pole
32
.
An inductive write head such as that shown in
FIG. 2
operates by passing a writing current through the conductive coil layer
48
. Because of the magnetic properties of the yoke
41
, a magnetic flux can be induced in the first and second poles
38
and
32
by a write current passed through the coil layer
48
. The write gap
36
allows the magnetic flux to fringe out from the yoke
41
(thus forming a fringing gap field) and to cross a magnetic recording medium that is placed proximate the ABS.
FIG. 3
shows an alternative magnetic write element
25
of the prior art including two conductive coil layers
60
and
62
. The overall structure of magnetic write element
25
is similar to write element
28
and includes a first pole
38
, a second pole
32
, a backgap
40
, a second pole pedestal
42
, a write gap
36
, and a first insulation layer
47
. The primary differences between this prior art write element
25
and write element
28
of
FIG. 2
is the additional write gap layer
27
of which the write gap
36
is part, and the arrangement of two stacked coil layers
60
and
62
rather than a single coil layer
48
.
In write element
25
the write gap layer
27
may be formed of a non-magnetic electrically insulating material disposed above the first insulation layer
47
. A first coil layer
60
is formed of first multiple winds
64
disposed above the write gap layer
27
. The first multiple winds
64
are insulated from one another, and covered by, a second insulation layer
65
. A second coil layer
62
is formed of second multiple winds
66
disposed above the second insulation layer
65
. The second multiple winds are insulated from one another, and covered by, a third insulation layer
67
. The first multiple winds
64
and the second multiple winds
66
are both formed of electrically conductive materials. The second insulating layer
65
and the third insulating layer
67
are both formed from non-magnetic electrically insulating materials. The second insulating layer
65
insulates the first coil layer
60
from the first pole
38
and from the second coil layer
62
. The third insulating layer
67
insulates the second coil layer
62
from the first pole
38
.
The write element
25
with two coil layers
60
and
62
has certain advantages over the write element
28
with one coil layer
48
. Stacking multiple coil layers permits write element
25
to be more compact, shortening the distance from the backgap
40
to the second pole pedestal
42
, a distance sometimes referred to as the yoke length YL. A shorter yoke length permits a shorter flux rise time, the length of time necessary for the fringing gap field across the write gap
36
to rise to its maximum intensity from its minimum intensity when an electric current is passed through the coil winds. The rate at which data may be written to a magnetic disk
16
increases as the flux rise time decreases. Therefore, a shorter yoke length allows higher data recording rates to be achieved.
Unfortunately, stacking multiple coil layers in a write element can be a disadvantage as well. Multiple coil layers can increase another parameter, sometimes referred to as the stack height SH, the distance between the top surface of the first pole
38
and the top of the second pole
32
. The increased topography of the write element created by a larger stack height can make the formation of the first pole
38
more difficult, leading to both decreased performance and lower yields.
FIG. 4
shows a head gimbal assembly (HGA) according to the prior art. The head gimbal assembly includes a base
21
attached to a load beam
23
. The load beam
23
includes an arm
20
attached between the base
21
and a suspension
22
. The suspension
22
is attached to the arm
20
at a first end and is atta
Corona Carlos
Crue, Jr. Billy W.
Shi Zhupei
Thomas Mark D.
Carr & Ferrell LLP
Read-Rite Corporation
Tupper Robert S.
Watko Julie Anne
LandOfFree
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