Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-01-23
2004-09-07
Tugbang, A. Dexter (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603070, C029S603120, C029S603130, C029S603140, C029S603160, C029S603180, C300S013000, C300S013000, C216S013000, C216S024000, C216S091000
Reexamination Certificate
active
06785955
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to magnetic recording, and more particularly to a method and system for providing a writer with improved performance due to the properties of the coil.
BACKGROUND OF THE INVENTION
Inductive writers are typically used to write data to recording media. Inductive writers can be broken into two types based on how their zero-throat position is defined. The zero throat for an inductive writer is the position at which the first and second poles begin to diverge at the back edge of the write gap. For example,
FIG. 1
depicts one conventional inductive writer
10
with a pedestal defined zero throat. The conventional writer
10
is typically part of a merged head that includes both a reader (not shown) and the conventional writer
10
. The conventional writer
10
includes a first pole
12
having a pedestal
14
, a first insulator
16
, a coil
18
, a second insulator
20
, a second pole
22
and a write gap
24
defined by the insulator-filled space between the first pole
12
and the second pole
22
. The first pole
12
and the second pole
22
are coupled through layer
21
. Although the coil
18
is shown as having six turns, typically the coil has another number of turns. As can be seen in
FIG. 1
, the pedestal
14
diverges from the front of the second pole
22
at the position marked by the arrow
23
. At this position, a portion of the first insulator
16
is flush with the pedestal
14
. Also at this point, the pedestal
14
draws away from the second pole
22
. Thus, the zero throat is defined by the pedestal
14
. The coil
18
typically has a pitch of approximately, 1.5 micros, with the narrowest width of the turns as 1.1-1.2 microns with a turn separation of 0.3-0.4 microns. When a current is driven through the coil
18
, magnetic field is concentrated at the write gap
24
by the poles
12
and
22
. The edge of the writer
10
near the write gap
24
is at the air-bearing surface (“ABS”), in proximity to the media. Thus, the conventional writer
10
can write to the media.
FIGS. 2A and 2B
depict conventional writers
10
′ and
10
″, respectively, in which the zero throat position is defined by the second insulator
20
′ and
20
″, respectively. Portions of the conventional writers
10
′ and
10
″ are analogous to portions of the conventional writer
10
depicted in FIG.
1
. Consequently, portions of the conventional writers
10
′ and
10
″ are labeled similarly. For example, the conventional writers
10
′ and
10
″ include a first pole
12
′ and
12
″, respectively. As can be seen in
FIG. 2A
, the second pole
22
′ separates from the first pole
12
′ due to the second insulator
20
′ at the position marked by the arrow
23
′. Similarly, in
FIG. 2B
, the second pole
22
″ separates from the first pole
12
″ due to the second insulator
20
″ at the position marked by the arrow
23
″. Thus, the conventional writer
10
′ and
10
″ define the zero throat position using the second insulator. The conventional writers
10
′ and
10
″ function in the same manner as the conventional writer
10
. The conventional writer
10
″ differs from the conventional writer
10
′ in that the coil
18
″ is sinked, residing on a depression in the first insulator
16
″.
FIG. 3A
depicts a flow-chart of a conventional method
50
for providing the conventional writers
10
and
10
′. The first pole is provided, via step
52
. The first insulator and pedestal are provided, via steps
54
and
56
, respectively. The first insulator and pedestal are then planarized, via step
58
. The write gap layer is then provided, via step
60
. The coil is provided, via steps
62
through
66
. A layer of photoresist is provided on the write gap, via step
62
. The photoresist is then patterned to provide a mask, via step
64
. The apertures in the mask are over locations on the first insulator where the coil will be plated. Thus, portions of the mask remaining indicate the spaces between the turns of the coil. The coil is then deposited, via step
66
. Typically, the coil is plated in step
66
. The coil typically has a pitch of no less than 1.5 microns, with spaces between the turns of the coil accounting for approximately 0.3-0.4 of the pitch. The second insulator and second pole are then provided, via steps
68
and
70
, respectively. Depending upon whether the writer is a conventional pedestal defined zero throat writer
10
or a conventional second insulator defined zero throat writer, the second insulator may diverge from the write gap differently.
FIG. 3B
depicts a conventional method
80
for providing the writer
10
″ in which the coil
18
″ is sinked. The first pole is provided, via step
82
. The first insulator is provided, via step
84
. The first insulator provided in step
84
is very thin, allowing the coil to be provided for the writer to be sinked such that the bottom of the coil is lower than the top of the pedestal, as in the writer
10
″. The pedestal is then provided, via step
86
. The pedestal is built up in step
86
such that the top of the pedestal is higher than the top of the first insulator. The write gap layer is then provided, via step
88
. The coil is provided, via steps
90
through
94
. A layer of photoresist is provided on the write gap, via step
90
. The photoresist is then patterned to provide a mask, via step
92
. The apertures in the mask are over locations on the first insulator where the coil will be plated. Thus, portions of the mask remaining indicate the spaces between the turns of the coil. The coil is then deposited, via step
94
. Typically, the coil is plated in step
94
. The coil typically has a pitch of no less than 1.5 microns, with spaces between the turns of the coil accounting for approximately 0.3-0.4 of the pitch. The second insulator and second pole are then provided, via steps
96
and
98
, respectively. Depending upon whether the writer is a conventional pedestal defined zero throat writer
10
or a conventional second insulator defined zero throat writer, the second insulator may diverge from the write gap differently.
Although the conventional writers
10
,
10
′ and
10
″ function, one of ordinary skill in the art will readily realize that there are several drawbacks to the conventional writers
10
,
10
′ and
10
″. The second insulator defined zero throat writers
10
′ and
10
″ have poorer overwrite performance than the conventional pedestal defined zero throat writer
10
. Thus, it is more difficult to overwrite data using the conventional writers
10
′ and
10
″ than the conventional writer
10
. This is particularly true for low currents driven in the coil
18
,
18
′ and
18
′. In addition, the writer
10
has a better controlled track width than the conventional writers
10
′ and
10
″ because the second insulator
20
, which has a significant topography, is located farther from the edge of the conventional writer
10
that will be at the ABS. Thus, for many applications, the conventional writer
10
is preferred over the conventional writers
10
′ and
10
″.
However, one of ordinary skill in the art will readily realize that there are also drawbacks to the conventional writer
10
. The conventional writer
10
has an apex angle. The apex angle is the angle the second pole
22
makes at the zero throat. This apex angle must be accounted for when placing the coil
18
in the writer
10
. The front turn of the coil
18
must be placed far enough away from the zero throat, and thus from the ABS, to ensure that the coil
18
is insulated from the second pole
22
. This also ensures that the track width can be controlled for the second pole
22
. Placing the coil
18
farther from the ABS reduces the efficiency of the combination of the coil
18
and poles
12
and
22
in providing a high magnetic field ne
Chen Benjamin
Chen Yingjian
Hiner Hugh Craig
Shi Xizeng
Sin Kyusik
Kim Paul
Sawyer Law Group LLP
Tugbang A. Dexter
Western Digital (Fremont) Inc.
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