Title: Method of lapping medium-opposing surface in thin-film magnetic head
Abstract: A thin-film magnetic head is formed on a support and is provided with a reproducing head part, a recording head part, and a heater for generating heat upon energization. A medium-opposing surface S of the magnetic head is polished while energizing the heater or recording head part.
Patent Number: 6,945,847 Issued on 09/20/2005 to Ota, et al.
| Inventors:
|
Ota; Norikazu (Tokyo, JP);
Kamigama; Takehiro (Tokyo, JP);
Oyama; Nobuya (Tokyo, JP);
Koide; Soji (Tokyo, JP);
Sasaki; Tetsuro (Tokyo, JP)
|
| Assignee:
|
TDK Corporation (Tokyo, JP)
|
| Appl. No.:
|
790794 |
| Filed:
|
March 3, 2004 |
Foreign Application Priority Data
| Mar 04, 2003[JP] | P2003-057436 |
| Current U.S. Class: |
451/7; 451/54 |
| Intern'l Class: |
B24B 049/00; B24B 001/00 |
| Field of Search: |
451/7,5-10,53-54,41
360/317,126
29/603.08,603.13,603.07
|
References Cited [Referenced By]
U.S. Patent Documents
| 6074283 | Jun., 2000 | Maeda et al.
| |
| 6414818 | Jul., 2002 | Tanimoto et al.
| |
| 6604989 | Aug., 2003 | Yanagida et al.
| |
| 2001/0013997 | Aug., 2001 | Sasaki et al.
| |
| 2002/0155794 | Oct., 2002 | Fatula et al.
| |
| 2004/0027728 | Feb., 2004 | Coffey et al.
| |
| 2004/0154159 | Aug., 2004 | Sasaki et al.
| |
| 2004/0235394 | Nov., 2004 | Ota et al.
| |
| 2004/0259474 | Dec., 2004 | Oyama et al.
| |
Primary Examiner: Wilson; Lee D.
Attorney, Agent or Firm: Oliff & Berridge, PLC
Claims
1. A method of lapping a medium-opposing surface in a thin-film magnetic head,
the method comprising the steps of:
providing the thin-film magnetic head formed on a support, the thin-film magnetic
head comprising a magnetoresistive device for reproducing, an inductive electromagnetic
transducer for writing, and a heater for generating heat when energized; and
polishing a medium-opposing surface of the thin-film magnetic head while energizing
the heater.
2. A method of lapping a medium-opposing surface in a thin-film magnetic head
according to claim 1, wherein the magnetoresistive device, inductive electromagnetic
transducer, and heater are laminated successively from the support side in the
thin-film magnetic head.
3. A method of lapping a medium-opposing surface in a thin-film magnetic head
according to claim 1, wherein the heater is disposed on a surface of the thin-film
magnetic head opposite from the support.
4. A method of lapping a medium-opposing surface in a thin-film magnetic head
according to claim 1, the method comprising the steps of:
cutting the support so as to form a bar including thin-film magnetic heads arranged
in a row; and
polishing medium-opposing surfaces of the thin-film magnetic heads in the bar
while energizing the heater.
5. A method of lapping a medium-opposing surface in a thin-film magnetic head
according to claim 4, the method comprising the steps of:
electrically connecting a plurality of heaters of the thin-film magnetic heads
to each other; and
polishing the medium-opposing surfaces of the thin-film magnetic heads while
energizing all the heaters in the bar with a single power supply.
6. A method of lapping a medium-opposing surface in a thin-film magnetic head
according to claim 4, wherein a plurality of heaters of the thin-film magnetic
heads in the bar are energized individually.
7. A method of lapping a medium-opposing surface in a thin-film magnetic head
according to claim 1, the method comprising the steps of:
cutting the support so as to form a bar including thin-film magnetic heads arranged
in a row;
cutting the bar so as to form a plurality of head sliders each having a thin-film
magnetic head;
mounting the head slider to an arm member so as to form a head gimbal assembly;
and
polishing the medium-opposing surface of the thin-film magnetic head in thus
obtained state while energizing the heater.
8. A method of lapping a medium-opposing surface in a thin-film magnetic head,
the method comprising the steps of:
providing the thin-film magnetic head formed on a support, the thin-film magnetic
head comprising a magnetoresistive device for reproducing and an inductive electromagnetic
transducer for writing; and
polishing a medium-opposing surface of the thin-film magnetic head while energizing
the electromagnetic transducer to produce a heat effect.
9. A method of lapping a medium-opposing surface in a thin-film magnetic head
according to claim 8, the method comprising the steps of:
cutting the support so as to form a bar including thin-film magnetic heads arranged
in a row; and
polishing medium-opposing surfaces of the thin-film magnetic heads in the bar
while energizing the electromagnetic transducer.
10. A method of lapping a medium-opposing surface in a thin-film magnetic head
according to claim 9, the method comprising the steps of:
electrically connecting a plurality of electromagnetic transducers of the thin-film
magnetic heads to each other; and
polishing the medium-opposing surfaces of the thin-film magnetic heads while
energizing all the electromagnetic transducers in the bar with a single power supply.
11. A method of lapping a medium-opposing surface in a thin-film magnetic head
according to claim 9, wherein a plurality of electromagnetic transducers of the
thin-film magnetic heads in the bar are energized individually.
12. A method of lapping a medium-opposing surface in a thin-film magnetic head
according to claim 8, the method comprising the steps of:
cutting the support so as to form a bar including thin-film magnetic heads arranged
in a row;
cutting the bar so as to form a plurality of head sliders each having a thin-film
magnetic head;
mounting the head slider to an arm member so as to form a head gimbal assembly;
and
polishing the medium-opposing surface of the thin-film magnetic head in thus
obtained state while energizing the electromagnetic transducer.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of lapping a medium-opposing surface
in a thin-film magnetic head.
2. Related Background Art
In general, a head gimbal assembly (HGA) is constructed by attaching a head slider
formed with a thin-film magnetic head to a leading end of a flexible arm member
such as a suspension. This head gimbal assembly is built into a hard disk drive
and carries out recording/reproducing with respect to a hard disk which is a recording
medium. At the time of recording/reproducing, an airflow accompanying the rotation
of the hard disk occurs under the thin-film magnetic head, thereby levitating the
thin-film magnetic head. As the hard disk attains a higher density, the gap between
the thin-film magnetic head and hard disk, i.e., head flying height, has been decreasing
to 10 nm, which currently seems to be the limit.
Under such circumstances, in a combination thin-film magnetic head in which
a magnetoresistive device for reproducing and an inductive electromagnetic transducer
for writing are laminated in this order on a support, a coil constituting the electromagnetic
transducer will generate heat when the inductive electromagnetic transducer is
energized. Then, the thin-film magnetic head will thermally expand in the vicinity
of the electromagnetic transducer in a surface opposing a recording surface of
the hard disk in the thin-film magnetic head, i.e., medium-opposing surface (ABS;
Air Bearing Surface), thereby projecting toward the hard disk. As a consequence,
the gap between the thin-film magnetic head and hard disk may decrease, thereby
causing the thin-film magnetic head and hard disk to crush against each other.
Therefore, the flying height of the thin-film magnetic head must be kept such that
the thin-film magnetic head and hard disk do not crush against each other even
when the vicinity of the electromagnetic transducer thermally expands. Hence, it
has been difficult for the thin-film magnetic head to fully achieve low levitation.
Known as examples of techniques for achieving lower levitation of the thin-film
magnetic head by preventing such a state from happening include one in which the
leading end part of an overcoat layer on the medium-opposing surface side in the
thin-film magnetic head is partly shaved to yield a step, and one in which the
glass transition temperature of a coil constituting the electromagnetic transducer
is set to about 70 to 100° C., so as to lower the Young's modulus, thereby
reducing the thermal stress occurring in the coil part (see, for example, Japanese
Patent Application Laid-Open No. 2000-306215).
SUMMARY OF THE INVENTION
However, the conventional techniques mentioned above may not fully restrain
the medium-opposing surface from projecting, and thus are hard to realize further
lower levitation in the thin-film magnetic head from now on.
While the inventors have been studying the forming of a heater for adjusting
the gap between a magnetoresistive device and a hard disk within the thin-film
magnetic head (publicly unknown), the problem mentioned above may occur in this
case as well.
It is an object of the present invention to provide a method of lapping a medium-opposing
surface in a thin-film magnetic head, which can prevent a thin-film magnetic head
and a hard disk from crushing against each other and thereby achieve lower levitation
in the thin-film magnetic head.
In a first aspect, the present invention provides a method of lapping a medium-opposing
surface in a thin-film magnetic head, the method comprising the steps of preparing
a thin-film magnetic head formed on a support, the thin-film magnetic head comprising
a magnetoresistive device for reproducing, an inductive electromagnetic transducer
for writing, and a heater for generating heat when energized; and polishing the
medium-opposing surface of the thin-film magnetic head while energizing the heater.
At the time of actual recording onto a hard disk, the electromagnetic transducer
of the thin-film magnetic head generates heat upon energization. As a consequence,
layers surrounding the electromagnetic transducer expand, whereby the medium-opposing
surface projects. In this aspect of the present invention, before the thin-film
magnetic head is built into the hard disk drive, the heater provided with the thin-film
magnetic head is caused to generate heat, so as to expand the medium-opposing surface
in the vicinity of the electromagnetic transducer, and thus expanded part is polished.
Therefore, even if the medium-opposing surface is expanded when the electromagnetic
transducer is energized at the time of actual recording onto the hard disk, the
flying height of the thin-film magnetic head can be set to an appropriate value.
This can prevent the thin-film magnetic head and hard disk from crushing against
each other, thereby realizing lower levitation in the thin-film magnetic head.
At the time of actual recording/reproducing with respect to the hard disk, the
heater may be used to generate heat, so as to adjust the distance between the magnetoresistive
device and hard disk. However, the heat from the heater may cause unintended parts
of the thin-film magnetic to expand thermally. Even in such a case, the lapping
method in accordance with this aspect of the present invention can eliminate the
unintended expanding parts beforehand.
Preferably, in this aspect of the present invention, the magnetoresistive
device, inductive electromagnetic transducer, and heater are laminated successively
from the support side in the thin-film magnetic head. When the electromagnetic
transducer is energized at the time of actual recording/reproducing with respect
to the hard disk, the electromagnetic transducer generates heat, so as to expand
its surroundings, thereby projecting the medium-opposing surface. Therefore, in
the medium-opposing surface at the time of recording/reproducing with respect to
the hard disk, the vicinity of the electromagnetic transducer comes the closest
to the hard disk.
In this aspect of the present invention, the heater is disposed not in the vicinity
of the magnetoresistive device but of the electromagnetic transducer, and is heated,
so as to expand the medium-opposing surface near the electromagnetic transducer,
whereas thus expanded part is polished. As a consequence, even if the medium-opposing
surface expands when the electromagnetic transducer is energized at the time of
actual recording onto the hard disk, the flying height of the thin-film magnetic
head can be set to an appropriate value. Therefore, the thin-film magnetic head
and hard disk can more reliably be prevented from crushing against each other.
The heater may be disposed on a surface of the thin-film magnetic head opposite
from the support. This makes it unnecessary for the heater to be formed within
the thin-film magnetic head, thus facilitating the making of the thin-film magnetic head.
The method may comprise the steps of cutting the support so as to form a bar
including thin-film magnetic heads arranged in a row; and polishing medium-opposing
surfaces of the thin-film magnetic heads in the bar while energizing the heater.
This makes it possible to lap a plurality of medium-opposing surfaces of thin-film
magnetic heads at once, which improves the working efficiency.
In this case, the method may comprise the steps of electrically connecting a
plurality
of heaters of the thin-film magnetic heads to each other; and polishing the medium-opposing
surfaces of the thin-film magnetic heads while energizing all the heaters in the
bar with a single power supply. This can polish a plurality of medium-opposing
surfaces of thin-film magnetic heads at once by fewer pieces of energizing equipment.
A plurality of heaters of the thin-film magnetic heads in the bar may be energized
individually. This allows the medium-opposing surfaces of the thin-film magnetic
heads to change their amounts of expansion separately from each other, thus making
it possible to adjust amounts of polishing in the individual thin-film magnetic
heads. Also, a step of placing the wiring necessary for connecting heaters to each
other and the like can be omitted, whereby the making of the thin-film magnetic
head becomes easier.
The method may comprise the steps of cutting the support so as to form a bar
including thin-film magnetic heads arranged in a row; cutting the bar so as to
form a plurality of head sliders each having a thin-film magnetic head; mounting
the head slider to an arm member so as to form a head gimbal assembly; and polishing
the medium-opposing surface of the thin-film magnetic head in thus obtained state
while energizing the heater. This can polish the medium-opposing surface of the
thin-film magnetic head in a state closer to the case actually mounted in the hard
disk drive, whereby optimal amounts of polishing can be carried out in the individual
thin-film magnetic heads. Therefore, the thin-film magnetic head and hard disk
can more reliably be prevented from crushing against each other.
In a second aspect, the present invention provides a method of lapping a medium-opposing
surface in a thin-film magnetic head, the method comprising the steps of preparing
a thin-film magnetic head formed on a support, the thin-film magnetic head comprising
a magnetoresistive device for reproducing and an inductive electromagnetic transducer
for writing; and polishing the medium-opposing surface of the thin-film magnetic
head while energizing the electromagnetic transducer.
At the time of actual recording onto a hard disk, the electromagnetic transducer
of the thin-film magnetic head generates heat upon energization. As a consequence,
layers surrounding the electromagnetic transducer expand, whereby the medium-opposing
surface projects. In this aspect of the present invention, before the thin-film
magnetic head is built into the hard disk drive, the electromagnetic transducer
is caused to generate heat, so as to expand the medium-opposing surface in the
vicinity of the electromagnetic transducer, and thus expanded part is polished.
Therefore, even if the medium-opposing surface is expanded when the electromagnetic
transducer is energized at the time of actual recording onto the hard disk, the
flying height of the thin-film magnetic head can be set to an appropriate value.
This can prevent the thin-film magnetic head and hard disk from crushing against
each other, thereby realizing lower levitation in the thin-film magnetic head.
The method may comprise the steps of cutting the support so as to form a bar
including thin-film magnetic heads arranged in a row; and polishing medium-opposing
surfaces of the thin-film magnetic heads in the bar while energizing the electromagnetic
transducer. This makes it possible to lap a plurality of medium-opposing surfaces
of thin-film magnetic heads at once, which improves the working efficiency.
In this case, the method may comprise the steps of electrically connecting a
plurality
of electromagnetic transducers of the thin-film magnetic heads to each other; and
polishing the medium-opposing surfaces of the thin-film magnetic heads while energizing
all the electromagnetic transducers in the bar with a single power supply. This
can polish a plurality of medium-opposing surfaces of thin-film magnetic heads
at once by fewer pieces of energizing equipment.
A plurality of electromagnetic transducers of the thin-film magnetic heads in
the
bar may be energized individually. This allows the medium-opposing surfaces of
the thin-film magnetic heads to change their amounts of expansion separately from
each other, thus making it possible to adjust amounts of polishing in the individual
thin-film magnetic heads. Also, a step of placing the wiring necessary for connecting
heaters to each other and the like can be omitted, whereby the making of the thin-film
magnetic head becomes easier.
The method may comprise the steps of cutting the support so as to form a bar
including thin-film magnetic heads arranged in a row; cutting the bar so as to
form a plurality of head sliders each having a thin-film magnetic head; mounting
the head slider to an arm member so as to form a head gimbal assembly; and polishing
the medium-opposing surface of the thin-film magnetic head in thus obtained state
while energizing the electromagnetic transducer. This can polish the medium-opposing
surface of the thin-film magnetic head in a state closer to the case actually mounted
in the hard disk drive, whereby optimal amounts of polishing can be carried out
in the individual thin-film magnetic heads. Therefore, the thin-film magnetic head
and hard disk can more reliably be prevented from crushing against each other.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a view showing a state in which a plurality of thin-film magnetic
heads to which the lapping method in accordance with a first embodiment of the
present invention is applied are formed on a support;
FIG. 1B is a view showing a state in which the support is cut, so as to produce
a plurality of bars each including thin-film magnetic heads arranged in a row;
FIG. 2 is a view showing a bar after MR height adjustment;
FIG. 3 is a schematic sectional view of the bar shown in FIG. 2 taken along
a direction perpendicular to the medium-opposing surface S;
FIG. 4 is a view showing the relationship between the medium-opposing surface
S of the thin-film magnetic head and a recording surface D of a hard disk;
FIG. 5 is a schematic view showing a state in which an external power supply
is connected to the bar shown in FIG. 2;
FIG. 6 is a partly enlarged view of a region VI in the bar shown in FIG. 5;
FIGS. 7A and 7B are views showing a bar holding device constituting a lapping
apparatus employed in the lapping method in accordance with the first embodiment
of the present invention;
FIG. 8 is a view showing a bar lapping step;
FIG. 9 is a schematic sectional view of the thin-film magnetic head after lapping;
FIG. 10 is a view showing an example of heater energizing mode;
FIG. 11 is a view showing an example of heater energizing mode;
FIGS. 12A and 12B are views showing a bar holding device in the mode shown
in FIG. 11;
FIG. 13 is a view showing another example of heater position in the thin-film
magnetic head;
FIG. 14 is a schematic sectional view showing an example of thin-film magnetic
head 1 in which heaters are arranged in a divided fashion;
FIG. 15 is a view showing a second embodiment of the present invention, illustrating
a mode of energizing a recording head part;
FIG. 16 is a view showing another example of the mode of energizing the recording
head part in accordance with the second embodiment of the present invention;
FIG. 17 is a schematic view showing a third embodiment of the present invention,
illustrating a lapping step in a state in which a head gimbal assembly is constructed; and
FIG. 18 is a graph showing results of experiments.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following, preferred embodiments of the present invention will be explained
in detail with reference to the accompanying drawings. Constituents identical to
each other will be referred to with numerals identical to each other, without repeating
their overlapping explanations.
[First Embodiment] FIG. 1A shows a state in which thin-film magnetic heads
1 to which the lapping method in accordance with a first embodiment is applied
are formed on a support
2 made of AlTiC (Al
2O
3.TiC)
or the like. FIG. 1B shows a state in which the support
2 is cut, so as
to produce a plurality of bars
3 each including the thin-film magnetic heads
1 arranged in a row. After preparing the thin-film magnetic heads
1,
the polishing step as described below is performed.
The polishing in the lapping method in accordance with this embodiment refers
to one applied to a medium-opposing surface in a thin-film magnetic head of the
bar
3 in the stage shown in FIG. 1B before, after, or in the middle of lapping
for adjusting the MR height or the like. The MR height refers to the distance in
the depth direction of the magnetoresistive device for reproducing as seen from
the medium-opposing surface. The medium-opposing surface is a surface opposing
a recording surface of a hard disk, and is known as air bearing surface (ABS) in
general. FIG. 2 shows a bar
3 after MR height adjustment.
The configuration of each thin-film magnetic head
1 to which the lapping
method in accordance with this embodiment is applied will now be explained.
FIG. 3 is a schematic sectional view of the bar
3 taken along a direction
perpendicular to the medium-opposing surface S in the thin-film magnetic head
1.
In FIG. 3, the thin-film magnetic head
1 is a combination thin-film magnetic
head in which a reproducing head part
11 having a GMR (Giant MagnetoResistive)
device
10 for reproducing and a recording head part
12 acting as
an inductive electromagnetic transducer for writing are laminated on the support
2. The GMR device utilizes a giant magnetoresistive effect yielding a high
magnetoresistance change ratio. Here, AMR (Anisotropic MagnetoResistive) devices
utilizing anisotropic magnetoresistive effects, TMR (Tunneling MagnetoResistive)
devices utilizing magnetoresistive effects occurring at tunnel junctions, CPP-GMR
devices, and the like may be used instead of the GMR device.
The support
2 is constructed by a substrate
22 made of AlTiC (Al
2O
3.TiC)
or the like, and an undercoat layer
21 made of an insulating material such
as alumina (Al
2O
3) formed thereon.
A lower shield layer
23 is formed on the undercoat layer
21, whereas
the GMR device
10 is formed above the lower shield layer
23. The
GMR device
10, which is constituted by a plurality of films in practice,
is depicted as a single layer.
The GMR device
10 is surrounded by an insulating layer
24 made
of Al
2O
3 or the like. On the insulating layer
24,
an upper shield layer
25 is formed.
The recording head part
12 is the one for longitudinal recording, and
mainly comprises a lower magnetic pole
13, an upper magnetic pole
14
magnetically coupled to the lower magnetic pole
13, and a thin-film coil
15 partly positioned between the lower magnetic pole
13 and upper
magnetic pole
14.
The upper magnetic pole
14 is constituted by a magnetic pole part layer
14a located on the medium-opposing surface S side, and a yoke part
layer
14b connected to the magnetic pole part layer
14a
while bypassing the thin-film coil
15 thereunder.
An overcoat layer
16 is formed on the upper magnetic pole
14. Formed
on the overcoat layer
16 is a heater
17 made of Cu, NiFe, Ta, Ti,
CoNiFe alloy, FeAlSi alloy, or the like. The heater
17 functions to generate
heat upon energization, so as to thermally expand layers thereabout, thus adjusting
the gap between the GMR device
10 and a hard disk. An overcoat layer
18
is further formed on the heater
17.
Two conductive parts
19a,
19b made of an electrically
conductive material such as Cu, each extending upward in the drawing, are electrically
connected to the heater
17. Heater electrode pads
20a,
20b
are attached to the conductive parts
19a,
19b at
their upper ends (on the surface of the overcoat layer
18), respectively.
Similarly, two conductive parts (not depicted) made of an electrically
conductive material are electrically connected to each of the reproducing head
part
11 and recording head part
12, so as to connect with their corresponding
reproducing and recording electrode pads at the upper ends of the conductive parts.
The reproducing and recording electrode pads will be explained later.
FIG. 4 is a view showing the relationship between the medium-opposing surface
S of the thin-film magnetic head
1 and a recording surface D of a hard disk.
When the heater
17 of the thin-film magnetic head
1 is energized,
the medium-opposing surface S thermally expands in the vicinity of the heater
17,
thereby projecting toward the recording surface D of the hard disk (as indicated
by the dash-double-dot line in the drawing). Here, the vicinity of a corner T on
the surface opposite from the support
2 in the overcoat layer
18
tends to project the farthest, thereby reducing the gap F between the medium-opposing
surface S and the recording surface D of the hard disk. This causes a possibility
of the corner T coming into contact with the recording surface D of the hard disk.
Therefore, in the lapping method of this embodiment, the overcoat layer
18 is polished from the corner T to the part indicated by a broken line
L in FIG. 4 while in a state where the vicinity of the heater
17 in the
medium-opposing surface S is expanded, i.e., in a state where the heater
17
is energized, before the thin-film magnetic head
1 is built into the hard
disk drive.
The lapping method of this embodiment will now be explained specifically.
FIG. 5 is a schematic view showing a state in which an external power supply
31 is connected to the bar
3 shown in FIG.
2. In this embodiment,
the heater
17 of each thin-film magnetic head
1 in the bar
3
is energized when the external power supply
31 is turned ON.
FIG. 6 is a partly enlarged view of a region VI of the bar
3 shown in
FIG. 5, illustrating two thin-film magnetic heads
1 arranged in a row. As
depicted, recording electrode pads
40a,
40b, heater
electrode pads
20a,
20b, and reproducing electrode
pads
41a,
41b are attached onto the overcoat layer
18 of each thin-film magnetic head
1. Though the recording electrode
pads
40a,
40b, heater electrode pads
20a,
20b, and reproducing electrode pads
41a,
41b
are provided successively from the left in the drawing, this order is not restrictive.
For example, the positions of the recording electrode pads
40a,
40b
may be exchanged with those of the reproducing electrode pads
41a,
41b. The positions of the heater electrode pads
20a,
20b are not restricted to the depicted mode, but may be arranged
on the outside of the recording electrode pads
40a,
40b
and reproducing electrode pads
41a,
41b, for example.
The heater electrode pads
20a,
20b of the thin-film
magnetic heads
1 adjacent each other are electrically connected to each
other by a wire
45, for example. Therefore, all the thin-film magnetic heads
1 in the bar
3 are electrically connected to each other, whereby
the heaters
17 of all the thin-film magnetic heads
1 in the bar
3
are energized when the external power supply
31 shown in FIG. 5 is turned
ON. This can reduce energizing equipment such as external power supplies.
FIG. 7A is a front view showing a bar holding device
51 constituting
a lapping apparatus employed in the lapping method in accordance with this embodiment,
whereas FIG. 7B is a side view thereof. The lapping apparatus is constituted by
the holding device
51 and a polisher
61 shown in FIG. 8 which will
be explained later.
As shown in FIGS. 7A and 7B, the bar holding device
51 comprises a main
part
52 and a holding rubber part
53, disposed thereunder, for holding
the bar
3. The main part
52 includes an energizing part
56
comprising a pair of electrodes
54 and a pair of wires
55 for energizing
the bar
3. The wires
55 are connected to the electrodes
54
and the bar
3 attached to the holding rubber part
53. The electrodes
54 are electrically connected to the external power supply
32, so
that the power from the external power supply
32 is supplied to the bar
3 by way of the wires
55.
FIG. 8 is a view showing a lapping step for the bar
3. For lapping, the
bar
3 is initially attached to the holding rubber part
53 of the
bar holding device
51. Subsequently, the bar holding device
51 is
moved down while the heaters
17 of the thin-film magnetic heads
1
in the bar
3 are energized, so that the bar
3 comes into contact
with the rotary polishing surface R in the polisher
61. Then, the overcoat
layer
18 is polished from the corner T to the part indicated by the broken
line L in FIG.
4.
FIG. 9 is a schematic sectional view of the thin-film magnetic head
1
taken along a direction perpendicular to the medium-opposing surface S after lapping.
The dash-double-dot line indicates the part shaved off by the lapping. FIG. 9 shows
only an example of form after lapping. A region extending from the corner T of
the overcoat layer
18 to the recording head part
12 or reproducing
head part
11 may be polished in some cases.
Lapping the thin-film magnetic head
1 as in the foregoing can set
the flying height of the thin-film magnetic head
1 to an appropriate amount
even if the medium-opposing surface S expands when the recording head part
12
is energized. This can prevent the thin-film magnetic head
1 and the recording
surface D of the hard disk from crushing against each other, thereby making it
possible for the thin-film magnetic head
1 to realize lower levitation.
The method of energizing the heaters
17 is not limited to the mode shown
in FIG.
6. For example, without providing heater electrode pads on the overcoat
layer
18 of the thin-film magnetic heads
1, the heaters
17
of the thin-film magnetic heads
1 adjacent each other may be directly connected
to each other by an embedded wire
45 as shown in FIG.
10.
As shown in FIG. 11, the heater electrode pads
20a,
20b
may be connected to an external power supply
70 for each thin-film magnetic
head
1. This allows the medium-opposing surfaces S of the thin-film magnetic
heads
1 to change their amounts of expansion separately from each other,
thus making it possible to adjust amounts of polishing in the individual thin-film
magnetic heads
1. Also, a step of placing the wiring necessary for connecting
heaters
17 to each other and the like can be omitted.
FIG. 12A is a front view showing the bar holding device
51 in the mode
shown in FIG. 11, whereas FIG. 12B is a side view thereof. For energizing the heaters
17 of the thin-film magnetic heads
1 in the bar
3, it will
be sufficient if wires
55 electrically connected to the external power supply
32 are connected to the individual heater electrode pads
20a,
20b as shown in FIGS. 12A and 12B. As a consequence, a step of providing
the wiring for connecting the heaters
17 to each other is unnecessary in
the bar
3. It is also advantageous in that amounts of energization of the
thin-film magnetic heads
1 can be changed individually, so that the medium-opposing
surfaces S can vary their amounts of expansion separately from each other.
The position of the heater
17 is not limited to that shown in FIG.
4.
The heater
17 may be located behind the recording head part
12 as
seen from the medium-opposing surface S, for example. Preferably, the reproducing
head part
11, recording head part
12, and heater
17 are laminated
in this order from the support
2 side as shown in FIG.
4. Namely,
it is preferred that the heater
17 be positioned closer to the recording
head part
12 than the reproducing head part
11. When the thin-film
coil
15 is energized at the time of recording onto the hard disk, the surroundings
of the recording head part
12 are expanded by the heat generated, whereby
the vicinity of the recording head part
12 comes the closest to the hard
disk. Therefore, polishing the most expandable part while expanding it with the
heater
17 can prevent the thin-film magnetic head
1 and the recording
surface D of the hard disk from crushing against each other. When the heater
17
is disposed within the overcoat layer
18 as shown in FIG. 4, the heater
17 may be located at any position within the overcoat layer
18 regardless
of the distance from the medium-opposing surface S or recording head part
12.
Though the heater
17 is disposed within the overcoat layer
18
of the thin-film magnetic head
1 in this embodiment, the heater
17
may be bonded by an adhesive or the like onto the surface of the overcoat layer
18 on the side opposite from the support
2 as shown in FIG.
13.
This makes it unnecessary to form the heater
17 within the thin-film magnetic
head
1, thus facilitating the making of the thin-film magnetic head
1.
Employing a configuration in which the heater
17 is bonded as such can yield
an effect similar to that obtained when the heater
17 is disposed within
the overcoat layer
18 of the thin-film magnetic head
1. Namely, as
shown in FIG. 13, the medium-opposing surface S can be expanded in the vicinity
of the heater
17 when the heater
17 is caused to generate heat upon energization.
A single heater
17 may be disposed at the above-mentioned position, or
a
plurality of heaters
17 may be arranged in a divided fashion. FIG. 14 is
a schematic sectional view showing an example of thin-film magnetic head
1
in which two heaters are arranged in a divided fashion. In this drawing, the heaters
60 arranged in a divided fashion are located at the same height as with
the heater
17 disposed within the overcoat layer
18 shown in FIG.
3.
The heater
17 provided in the thin-film magnetic head
1 in accordance
with this embodiment may be used for generating heat upon energization at the time
of recording/reproducing with respect to a hard disk, so as to expand the medium-opposing
surface S in the vicinity of the reproducing head part
11, thereby adjusting
the gap between the reproducing head part
11 and the hard disk. Alternatively,
the heater
17 may be used only for expanding the medium-opposing surface
when carrying out the lapping in accordance with this embodiment but not when operating
the hard disk drive.
[Second Embodiment] A second embodiment of the present invention will now
be explained. The lapping method of this embodiment differs from that of the first
embodiment in that the recording head part
12 is caused to generate heat
upon energization instead of the heater
17 in the thin-film magnetic head
1.
In the lapping method in accordance with the second embodiment, before the thin-film
magnetic head
1 is built into the hard disk drive, the recording head part
12 is caused to generate heat upon energization, so as to project the medium-opposing
surface S, and the projected part of the medium-opposing surface S is polished
in this state.
As a consequence, the part of medium-opposing surface S expandable by the heat
generated by the recording head part
12 at the time of actual recording
onto the hard disk is eliminated beforehand, whereby the flying height of the thin-film
magnetic head
1 can be set to an appropriate value. This can prevent the
thin-film magnetic head
1 and the recording surface D of the hard disk from
crushing against each other, and make it possible for the thin-film magnetic head
to realize lower levitation.
FIG. 15 is a view showing a mode of energization of the recording head part
12 in this embodiment. In this drawing, recording electrode pads
40a,
40b are electrically connected to the recording head part
12
by a wire
45, for example, between thin-film magnetic heads
1 adjacent
each other. Therefore, the respective recording heads
12 of all the thin-film
magnetic heads
1 in the bar
3 are electrically connected to each
other, so that the recording head parts
12 of all the thin-film magnetic
heads
1 in the bar
3 are energized when the external power supply
31 shown in FIG. 5 is turned ON. This can polish the medium-opposing surfaces
S of a plurality of thin-film magnetic heads
1 at once, thereby reducing
energizing equipment such as external power supplies.
FIG. 16 is a view showing another example of mode of energizing the recording
heat part
12 in this embodiment. As shown in this drawing, the recording
electrode pads
40a,
40b may be connected to an external
power supply
80 for each thin-film magnetic head
1. This allows the
medium-opposing surfaces S of the thin-film magnetic heads
1 to change their
amounts of expansion separately from each other, thus making it possible to adjust
amounts of polishing in the individual thin-film magnetic heads
1. Also,
a step of placing the wiring necessary for connecting the recording head parts
12 to each other and the like can be omitted, so as to facilitate the making
of the thin-film magnetic heads
1.
[Third Embodiment] A third embodiment of the present invention will now be
explained. FIG. 17 is a schematic view showing the lapping in a state where a head
gimbal assembly is assembled. Though the medium-opposing surfaces S of thin-film
magnetic heads
1 are polished while in the state of a bar
3 in which
the thin-film magnetic heads
1 are arranged in a row in the first and second
embodiments, the medium-opposing surface S of each thin-film magnetic head
1
may be polished while in the state of a head gimbal assembly as shown in FIG.
17.
Namely, the bar
3 is cut, so as to form head sliders
71 each
including a thin-film magnetic head
1, and each head slider
71 is
mounted to an arm member
72 such as a suspension, so as to produce a head
gimbal assembly
73. While in this state, the medium-opposing surface S of
the thin-film magnetic head
1 is polished while energizing the heater
17
or recording head part
12. This can polish the medium-opposing surface S
of the thin-film magnetic head
1 in a state closer to the case actually
mounted in a hard disk drive, whereby optimal amounts of polishing can be carried
out in the individual thin-film magnetic heads. Therefore, the thin-film magnetic
head
1 and hard disk can more reliably be prevented from crushing against
each other.
Next, an example of the present invention will be explained with reference
to the graph of FIG.
18. In this example, thin-film magnetic heads employing
the lapping method in accordance with the present invention (having the configuration
shown in FIG. 9) and thin-film magnetic heads not subjected to lapping (substantially
having the configuration shown in FIG. 3) were prepared. Subsequently, after the
thin-film magnetic heads were levitated on the recording surface of a hard disk,
their heaters were energized, so as to gradually increase the voltage applied to
the heaters. Then, the voltage applied until the thin-film magnetic head came in
contact with the hard disk as being expanded by the heat generated was measured.
In FIG. 18, the ordinate indicates the positional relationship between a recording
surface of a hard disk and the reproducing head part of each thin-film magnetic
head. The distance from the hard disk to the reproducing head part in the state
not energizing the heater was set to 0, whereas the value H (nm) by which the flying
height was reduced when the heater was energized is indicated with a minus sign
added thereto. Namely, the greater is the absolute value on the ordinate, the smaller
is the flying height of the thin-film magnetic head from the hard disk. On the
other hand, the abscissa indicates the value of power P (mW) applied to the heater.
Experiment 1 employed the thin-film magnetic heads not subjected to lapping
(results thereof being indicated by line A). Experiment 2 employed the thin-film
magnetic heads whose medium-opposing surfaces were lapped by 2.5 nm (results thereof
being indicated by line B). Experiment 3 employed the thin-film magnetic heads
whose medium-opposing surfaces were lapped by 7.5 nm (results thereof being indicated
by line C).
In Experiment 1, as can be seen from line A, the leading end part of the thin-film
magnetic head abutted against the recording surface of the hard disk at a point
where the applied power value P was about 100 mW, so that the distance H between
the reproducing head part and the recording surface of the hard disk could not
be made shorter from there.
In Experiment 2, as can be seen from line B, the leading end part of the thin-film
magnetic head abutted against the recording surface of the hard disk at a point
where the applied power value P was about 120 mW, so that the distance H between
the reproducing head part and the recording surface of the hard disk became shorter
than that in line A.
In Experiment 3, as can be seen from line C, the voltage could be applied up
to
about 160 mW, whereby the distance H between the reproducing head part and the
recording surface of the hard disk became shortest.
The foregoing has verified that the distance H between the reproducing head part
and the recording surface of the hard disk can be made shorter as the amount of
lapping is greater. Therefore, lapping the medium-opposing surface of a thin-film
magnetic head can improve recording and reproducing performances of the thin-film
magnetic head.
Though the present invention is specifically explained with reference to the
embodiments in the foregoing, the present invention is not limited to the above-mentioned
embodiments. For example, though the thin-film magnetic heads employ the in-plane
recording scheme in the above-mentioned embodiments, the present invention is also
applicable to thin-film magnetic heads of perpendicular recording type.
Since the medium-opposing surface of a thin-film magnetic head is lapped while
energizing a heater or electromagnetic transducer, the present invention can prevent
the thin-film magnetic head and a hard disk from crushing against each other and
thereby achieve lower levitation in the thin-film magnetic head.
The basic Japanese Application No. 2003-57436 filed on Mar. 4, 2003 is hereby
incorporated by reference.
*
