U.S. patent application number 09/742060 was filed with the patent office on 2001-07-19 for apparatus and method for processing thin-film magnetic head material.
This patent application is currently assigned to TDK CORPORATION. Invention is credited to Ishizaki, Kazuo, Itoh, Hiroyuki.
Application Number | 20010008826 09/742060 |
Document ID | / |
Family ID | 18533742 |
Filed Date | 2001-07-19 |
United States Patent
Application |
20010008826 |
Kind Code |
A1 |
Ishizaki, Kazuo ; et
al. |
July 19, 2001 |
Apparatus and method for processing thin-film magnetic head
material
Abstract
An apparatus main body has a surface plate, a vertical shaft and
an arm coupled to the vertical shaft such that it can move in the
vertical direction. A spline shaft is attached to the arm such that
it can move in the vertical direction. A keeper for holding a
workpiece is attached to the lower end of the spline shaft. To the
arm, attached are: reference position sensor for detecting the
position of the top surface of a reference base as a reference
position; and a workpiece thickness sensor for detecting the
position of the top surface of the keeper as a position associated
with the thickness of the workpiece. During a process on the
workpiece, the absolute thickness of the workpiece is recognized
based on information detected by the sensors, and the processing
operation is controlled such that the thickness will become a
desired value.
Inventors: |
Ishizaki, Kazuo; (Tokyo,
JP) ; Itoh, Hiroyuki; (Tokyo, JP) |
Correspondence
Address: |
Oliff & Berridge PLC
P.O. Box 19928
Alexandria
VA
22320
US
|
Assignee: |
TDK CORPORATION
|
Family ID: |
18533742 |
Appl. No.: |
09/742060 |
Filed: |
December 22, 2000 |
Current U.S.
Class: |
451/5 |
Current CPC
Class: |
B24B 37/048 20130101;
B24B 49/04 20130101; B24B 37/013 20130101 |
Class at
Publication: |
451/5 |
International
Class: |
B24B 049/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 13, 2000 |
JP |
2000-5054 |
Claims
What is claimed is:
1. An apparatus for processing a thin-film magnetic head material
comprising: a processing machine which performs a polishing process
on a thin-film magnetic head material in which sections to become
sliders each including a thin-film magnetic head element are
arranged in a row; a first detector which detects a reference
position; a second detector which detects a position which changes
depending on the thickness of the material; and a controller which
recognizes the thickness of the material based on the reference
position detected by the first detector and the position detected
by the second detector and controls the processing machine such
that the thickness of the material becomes a predetermined
value.
2. The apparatus according to claim 1 wherein the processing
machine has a rotating surface plate, the apparatus further
comprising a processing jig for holding the material such that a
surface of the material to be polished is put into contact with the
surface plate.
3. The apparatus according to claim 2, wherein: the processing jig
holds the material having a band-shaped protective member applied
to a surface thereof opposite to the surface to be polished; and
the processing jig has: a first member having a hole at a lower end
thereof, the hole allowing the material to pass therethrough and
disallowing the protective member to pass therethrough; and a
second member coupled to the first member, the first and second
members sandwiching the protective member therebetween.
4. The apparatus according to claim 3, wherein the first member has
a plurality of said holes.
5. The apparatus according to claim 3, wherein a plurality of types
of first members are provided as said first member which are
different from each other in at least either the length or position
of said hole.
6. The apparatus according to claim 5, wherein the position of an
outermost end of said hole is uniformly set for said plurality of
types of first members.
7. The apparatus according to claim 2, wherein a plurality of types
of processing jigs are provided as said processing jig, each of the
processing jigs having a position regulating section for placing
the material in a predetermined position, the jigs being different
from each other in at least either the length or position of the
position regulating section thereof, and the position of an
outermost end of the position regulating section thereof being
uniformly set for the plurality of types of processing jigs.
8. The apparatus according to claim 1, wherein the first detector
and the second detector are mounted on the same arm.
9. The apparatus according to claim 1, wherein the first detector
and the second detector intermittently perform the detecting
operation.
10. The apparatus according to claim 1, wherein the controller
recognizes the thickness of the material based on the result of
detection carried out plural times by the first detector and the
second detector.
11. A method for processing a thin-film magnetic head material
utilizing an apparatus for processing a thin-film magnetic head
material that has: a processing machine which performs a polishing
process on a thin-film magnetic head material in which sections to
become sliders each including a thin-film magnetic head element are
arranged in a row; a first detector which detects a reference
position; and a second detector which detects a position which
changes depending on the thickness of the material, the method
comprising the steps of: detecting a reference position using the
first detector and detecting a position which changes depending on
the thickness of the material using the second detector;
recognizing the thickness of the material based on the reference
position detected by the first detector and the position detected
by the second detector; and performing the processing by
controlling the processing machine based on the recognized
thickness of the material such that the thickness becomes a
predetermined value.
12. The method according to claim 11 wherein: the processing
machine has a rotating surface plate; and the material is held
using a processing jig such that a surface of the material to be
polished is put into contact with the surface plate in the step of
performing the processing.
13. The method according to claim 12 wherein: the processing jig
holds the material having a band-shaped protective member applied
to a surface thereof opposite to the surface to be polished; and
the processing jig has: a first member having a hole at a lower end
thereof, the hole allowing the material to pass therethrough and
disallowing the protective member to pass therethrough; and a
second member coupled to the first member, the first and second
members sandwiching the protective member therebetween.
14. The method according to claim 13, wherein the first member has
a plurality of said holes.
15. The method according to claim 13, wherein a plurality of types
of first members are provided as said first member which are
different from each other in at least either the length or position
of said hole.
16. The method according to claim 15, wherein the position of an
outermost end of said hole is uniformly set for said plurality of
types of first members.
17. The method according to claim 12, wherein a plurality of types
of processing jigs are provided as said processing jig, each of the
processing jigs having a position regulating section for placing
the material in a predetermined position, the jigs being different
from each other in at least either the length or position of the
position regulating section thereof, and the position of an
outermost end of the position regulating section thereof being
uniformly set for the plurality of types of processing jigs.
18. The method according to claim 11, wherein the first detector
and the second detector are mounted on the same arm.
19. The method according to claim 11, wherein the detecting step
intermittently detects the positions.
20. The method according to claim 11, wherein the recognizing step
recognizes the thickness of the material based on the result of
detection carried out plural times by the first detector and the
second detector.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus and method for
processing a thin-film magnetic head material that are used for
polishing a thin-film magnetic head material having a row of
sections to become sliders each of which includes a thin-film
magnetic head element.
[0003] 2. Description of the Related Art
[0004] In general, a flying-type thin-film magnetic head used in a
magnetic disk drive or the like is constituted by a slider having a
thin-film magnetic head element at a rear end thereof. In general,
the slider has a rail section whose surface serves as a medium
facing surface (an air bearing surface) and a tapered section or
step portion in the vicinity of the end on an air inflow side
thereof. The rail section is slightly floated above the surface of
a recording medium such as a magnetic disk by a stream of air that
flows in through the tapered section or step section.
[0005] In general, such sliders are manufactured by cutting a wafer
in one direction, the wafer having a plurality of rows of sections
to become sliders (hereinafter referred to as slider sections) each
including a thin-film magnetic head element. Materials referred to
as "bars" on which the slider sections are arranged in a row are
thereby formed. The bars are then cut into sliders. A surface of a
bar which is to become a medium facing surface (hereinafter
referred to as "medium facing surface" for convenience) is
subjected to processes such as lapping and formation of a rail
portion. Such process may be performed before or after the
formation of the bar.
[0006] In the process of manufacturing a slider as described above,
the ultimate thickness of the slider or the profile of the medium
facing surface may be controlled by lapping the surface of the bar
opposite to the medium facing surface before or after the
processing of the medium facing surface of the bar, or by lapping
two surfaces of a block in which two rows of slider sections are
arranged such that the medium facing surfaces thereof face each
other, the two surfaces of the block being opposite to the medium
facing surfaces.
[0007] Two methods as described below have been available for
lapping the surface of the above-described thin-film magnetic head
material as described above opposite to the medium facing surface
(hereinafter referred to as "back surface").
[0008] A first method is to lap the back surface before lapping the
medium facing surface. This method is primarily employed when a
material in the form of a block is used in which two rows of slider
sections are arranged such that the medium facing surfaces face
each other. When such a material is used, a double-side lapping
apparatus is frequently used to lap both sides of the material.
[0009] A second method is to lap the back surface after lapping the
medium facing surface. This method is employed when using a bar
formed by cutting a wafer in one direction, in which a plurality of
rows of slider sections are aligned and oriented, for example, in
the same direction. This method is often conducted by bonding the
back surface of the bar to an appropriate jig, lapping the medium
facing surface of the bar, removing the bar from the jig thereafter
and bonding the medium facing surface of the bar to the jig to lap
the back surface of the bar.
[0010] In either of the above-described two methods, the process
(lapping) must be controlled such that the thickness of the
material which is a workpiece attains a desired value. In order to
control the thickness of the material, the processing time is
controlled, for example, in prior art. Referring to the processing
operation in such a case, the operator measures the thickness of
the material and accordingly sets a processing time in the
processing apparatus. In order to improve accuracy in processing,
after starting the processing operation the operator measures the
thickness of the material and adjusts the processing time once or
more times by interrupting the process each time.
[0011] Recently, there are needs for compact sliders which are
floated by only a small amount in order to achieve high density
recording. The accuracy of the thickness of a thin-film magnetic
head material has a significant influence not only on the accuracy
of the thickness of the slider but also on the accuracy of the
formation of a rail on the slider. Therefore, in order to provide a
compact slider which is floated by only a small amount, the
thickness of the thin-film magnetic head material must be
accurately controlled.
[0012] In the case of above-described method in which the back
surface of the thin-film magnetic head material is processed by
controlling the processing time, however, the processing accuracy
is low because there is significant variation in processing
depending on the state of the surface plate, slurry and the like
and on the operator. This results in a problem in that it is
difficult to accurately control the thickness of the thin-film
magnetic head material. Further, it has a problem in that an
operator must repeat the measurement of the thickness of the
material and processing of the same many times to improve
processing accuracy, which increases the number of steps and
reduces operating efficiency.
[0013] Especially, when the back surface of the bar is lapped after
lapping the medium facing surface, the above-mentioned reduction in
operating efficiency is significant because there are increased
number of lapping steps compared to lapping of both sides of a
material in the form of a block in which slider sections are
arranged in two rows. Further, when the back surface of the bar is
lapped after lapping the medium facing surface thereof, the
measurement of thickness of the material and processing of the same
repeated many times result in a problem in that the lapped medium
facing surface may deteriorate and in that a thin film such as a
GMR (giant magnetoresistive) film may be broken by electrostatic
discharge (ESD).
OBJECTS AND SUMMARY OF THE INVENTION
[0014] It is a first object of the invention to provide an
apparatus and a method for processing a thin-film magnetic head
material which make it possible to improve the accuracy and
efficiency of a process of polishing the material.
[0015] In addition to the first object, it is a second object of
the invention to provide an apparatus and a method for processing a
thin-film magnetic head material which make it possible to polish
the surface of the material opposite to the medium facing surface
thereof while protecting the medium facing surface.
[0016] An apparatus for processing a thin-film magnetic head
material according to the invention comprises:
[0017] a processing machine which performs a polishing process on a
thin-film magnetic head material in which sections to become
sliders each including a thin-film magnetic head element are
arranged in a row;
[0018] a first detector which detects a reference position;
[0019] a second detector which detects a position which changes
depending on the thickness of the material; and
[0020] a controller which recognizes the thickness of the material
based on the reference position detected by the first detector and
the position detected by the second detector and controls the
processing machine such that the thickness of the material becomes
a predetermined value.
[0021] In the apparatus according to the invention, the first
detector detects the reference position; the second detector
detects the position which changes depending on the thickness of
the material; and the controller recognizes the thickness of the
material based on the positions detected by the two detectors and
controls the processing machine such that the thickness of the
material becomes the predetermined value.
[0022] In the apparatus according to the invention, the processing
machine may have a rotating surface plate, and the apparatus may
further comprise a processing jig for holding the material such
that a surface of the material to be polished is put into contact
with the surface plate.
[0023] The processing jig may hold the material having a
band-shaped protective member applied to a surface thereof opposite
to the surface to be polished. The processing jig may have: a first
member having a hole at a lower end thereof, the hole allowing the
material to pass therethrough and disallowing the protective member
to pass therethrough; and a second member coupled to the first
member, the first and second members sandwiching the protective
member therebetween.
[0024] The first member may have a plurality of the holes described
above. As the first member, a plurality of types of the first
members may be provided which are different from each other in at
least either the length or position of the hole thereof. The
position of an outermost end of the hole may be uniformly set for
the plurality of types of the first members.
[0025] In the apparatus according to the invention, a plurality of
types of processing jigs may be provided as the processing jig
described above, each of the processing jigs having a position
regulating section for placing the material in a predetermined
position. The jigs are different from each other in at least either
the length or position of the position regulating section thereof.
The position of an outermost end of the position regulating section
is uniformly set for the plurality of types of the jigs.
[0026] In the apparatus according to the invention the first
detector and the second detector may be mounted on the same
arm.
[0027] In the apparatus according to the invention, the first
detector and the second detector may intermittently perform the
detecting operation.
[0028] In the apparatus according to the invention the controller
may recognize the thickness of the material based on the result of
detection carried out plural times by the first detector and the
second detector.
[0029] A method according to the invention is provided for
processing a thin-film magnetic head material, utilizing an
apparatus for processing a thin-film magnetic head material that
has: a processing machine which performs a polishing process on a
thin-film magnetic head material in which sections to become
sliders each including a thin-film magnetic head element are
arranged in a row; a first detector which detects a reference
position; and a second detector which detects a position which
changes depending on the thickness of the material. The method
comprises the steps of:
[0030] detecting a reference position using the first detector and
detecting a position which changes depending on the thickness of
the material using the second detector;
[0031] recognizing the thickness of the material based on the
reference position detected by the first detector and the position
detected by the second detector; and
[0032] performing the processing by controlling the processing
machine based on the recognized thickness of the material such that
the thickness becomes a predetermined value.
[0033] In the method according to the invention, the processing
machine may have a rotating surface plate; and the material may be
held using a processing jig such that a surface of the material to
be polished is put into contact with the surface plate in the step
of performing the processing.
[0034] In the method according to the invention, the processing jig
may hold the material having a band-shaped protective member
applied to a surface thereof opposite to the surface to be
polished; and the processing jig may have: a first member having a
hole at a lower end thereof, the hole allowing the material to pass
therethrough and disallowing the protective member to pass
therethrough; and a second member coupled to the first member, the
first and second members sandwiching the protective member
therebetween.
[0035] The first member may have a plurality of holes described
above. As the first member, a plurality of types of the first
members may be provided which are different from each other in at
least either the length or position of the hole thereof. The
position of an outermost end of the hole may be uniformly set for
the plurality of types of the first members.
[0036] In the method according to the invention, a plurality of
types of processing jigs may be provided as the processing jig
described above, each of the processing jigs having a position
regulating section for placing the material in a predetermined
position. The jigs are different from each other in at least either
the length or position of the position regulating section thereof.
The position of an outermost end of the position regulating section
is uniformly set for the plurality of types of the jigs.
[0037] In the method according to the invention, the first detector
and the second detector may be mounted on the same arm.
[0038] In the method according to the invention, the detecting
steps may intermittently detect the positions.
[0039] In the method according to the invention, the recognizing
step may recognize the thickness of the material based on the
result of detection carried out plural times by the first detector
and the second detector.
[0040] Other objects, features and advantages of the invention will
become sufficiently apparent from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1 is a front view of a processing apparatus according
to an embodiment of the invention showing a general configuration
thereof.
[0042] FIG. 2 is a front view of a major part of the processing
apparatus according to the embodiment of the invention showing a
state thereof during an adjusting operation.
[0043] FIG. 3 is a front view of the major part of the processing
apparatus according to the embodiment of the invention showing a
state thereof during a processing operation.
[0044] FIG. 4 is a block diagram showing a circuit configuration of
the processing apparatus according to the embodiment of the
invention.
[0045] FIG. 5 is a sectional view of a processing jig in the
embodiment of the invention showing a state in which a workpiece is
fixed on the same.
[0046] FIG. 6 is a perspective view of the workpiece in the
embodiment of the invention.
[0047] FIG. 7 is a plan view of a carrier of the processing jig in
the embodiment of the invention.
[0048] FIG. 8 is a plan view showing an example of the carrier in
the embodiment of the invention.
[0049] FIG. 9 is a plan view showing another example of the carrier
in the embodiment of the invention.
[0050] FIG. 10 is a plan view showing still another example of the
carrier in the embodiment of the invention.
[0051] FIG. 11 is a plan view showing still another example of the
carrier in the embodiment of the invention.
[0052] FIG. 12 is a plan view showing still another example of the
carrier in the embodiment of the invention.
[0053] FIG. 13 is a plan view showing still another example of the
carrier in the embodiment of the invention.
[0054] FIG. 14 is a plan view showing still another example of the
carrier in the embodiment of the invention.
[0055] FIG. 15 is a plan view showing still another example of the
carrier in the embodiment of the invention.
[0056] FIG. 16 is a plan view showing still another example of the
carrier in the embodiment of the invention.
[0057] FIG. 17 is a plan view showing still another example of the
carrier in the embodiment of the invention.
[0058] FIG. 18 is a plan view showing still another example of the
carrier in the embodiment of the invention.
[0059] FIG. 19 is a flow chart of steps of the processing operation
utilizing the processing apparatus according to the embodiment of
the invention.
[0060] FIG. 20 is an illustration showing a step for manufacturing
a slider in the embodiment of the invention.
[0061] FIG. 21 is an illustration showing another step for
manufacturing a slider in the embodiment of the invention.
[0062] FIG. 22 is an illustration showing still another step for
manufacturing a slider in the embodiment of the invention.
[0063] FIG. 23 is an illustration showing still another step for
manufacturing a slider in the embodiment of the invention.
[0064] FIG. 24 is an illustration showing still another step for
manufacturing a slider in the embodiment of the invention.
[0065] FIG. 25 is an illustration showing still another step for
manufacturing a slider in the embodiment of the invention.
[0066] FIG. 26 is an illustration showing still another step for
manufacturing a slider in the embodiment of the invention.
[0067] FIG. 27 is a distribution diagram showing an example of
distribution of the thicknesses of a plurality of workpieces before
a process using the processing apparatus according to the
embodiment of the invention.
[0068] FIG. 28 is a distribution diagram showing an example of
distribution of the thicknesses of the plurality of workpieces
after the process using the processing apparatus according to the
embodiment of the invention.
[0069] FIG. 29 is an illustration showing a comparison between the
thicknesses of the plurality of workpieces before and after the
process using the processing apparatus according to the embodiment
of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0070] An embodiment of the invention will now be described in
detail with reference to the drawings.
[0071] FIG. 1 is a front view of an apparatus for processing a
thin-film magnetic head material according to an embodiment of the
invention (hereinafter simply referred to as "processing
apparatus") showing a general configuration thereof. Each of FIGS.
2 and 3 is a front view of a major part of the processing apparatus
according to the embodiment of the invention. FIG. 2 shows a state
during an adjusting operation, and FIG. 3 shows a state during a
processing operation.
[0072] The processing apparatus according to the present embodiment
has an apparatus main body 1 for performing a polishing process on
workpieces and a control panel 2 for inputting information on the
workpieces and processing conditions and showing various
indications. In the present embodiment, the workpiece is a
thin-film magnetic head material in which sections to become
sliders each including a thin-film magnetic head element
(hereinafter referred to as "bars") are arranged in a row. The
polishing process in the present embodiment is lapping. The
apparatus main body 1 has three surface plates 3, two vertical
shafts 4 provided on each surface plate 3 and an arm 5 provided on
each shaft 4. The arms 5 are coupled to the vertical shafts 4 such
that they can move in vertical and horizontal (forward and
backward) directions.
[0073] Spline shafts 6 are attached to the arms 5 such that they
can move in the vertical direction. Keepers 7 for holding
workpieces are attached to the lower ends of the spline shafts 6.
Weights 8 are attached to the spline shafts 6 in the vicinity of
the upper ends thereof.
[0074] Reference position sensors 11 as the first detector which
detects reference positions and workpiece thickness sensors 12 as
the second detector which detects positions associated with
thicknesses of the workpieces which change as a result of a process
are attached to the arms 5. The reference position sensors 11 are
provided in positions outside the periphery of the surface plates
3. The workpiece thickness sensors 12 are provided in positions
above the keepers 7. Reference bases 13 in the form of blocks for
indicating reference positions are provided under the reference
position sensors 11. The reference position sensors 11 detect the
positions of the top surfaces of the reference bases 13 as
reference positions. The workpiece thickness sensors 12 detect
positions of the top surfaces of the keepers 7 as the positions
associated with the thicknesses of the workpieces which change as a
result of a process.
[0075] The reference position sensors 11 and workpiece thickness
sensors 12 may be contact type sensors or non-contact type sensors.
The "TESA Module" manufactured by TESA Corp. or the like may be
used as the contact type sensor. The "Microsense" manufactured by
ADE Corp. may be used as the non-contact type sensor. Sensors
having good temperature characteristics are preferably used as the
sensors 11 and 12 because there may be temperature changes in the
vicinity of the sensors 11 and 12 during processing. For example,
such sensors with good temperature characteristics include glass
scale type sensors (e.g., sensors manufactured by Union Tool
Corp.).
[0076] FIG. 4 is a block diagram showing a circuit configuration of
the processing apparatus according to the present embodiment. FIG.
4 shows only parts associated with one of the arms 5. As shown in
FIG. 4, the processing apparatus has a driving portion 15 for
driving the surface plate 3 and arm 5, and a control portion 16 for
controlling the driving portion 15. The control panel 2, the
reference position sensor 11 and the workpiece thickness sensor 12
are connected to the control portion 16. The control portion 16
controls the driving portion 15 according to information on the
workpiece, processing conditions, etc. input from the control panel
2 and controls the driving portion 15 such that the thickness of
the workpiece becomes a predetermined value by recognizing the
thickness of the workpiece based on a reference position detected
by the reference portion sensor 11 and a position detected by the
workpiece thickness sensor 12. The control portion 16 also causes
the control panel 2 to display information of the thickness of the
workwpiece and so on thus recognized. For example, the control
portion 16 is constituted by a computer. The control portion 16
corresponds to the controller of the present invention.
[0077] A description will now be made with reference to FIGS. 5
through 7 on an operation of a processing jig in the present
embodiment for holding a workpiece such that a surface of the
workpiece to be polished is in contact with the surface plate 3.
FIG. 5 is a sectional view showing a state in which the workpiece
is fixed on the processing jig. FIG. 6 is a perspective view of the
workpiece. FIG. 7 is a plan view of a carrier of the processing
jig.
[0078] As shown in FIG. 6, a workpiece 20 or bar is in the form of
an elongate plate. A surface (hereinafter referred to "back
surface") of the workpiece 20 opposite to a surface thereof to
become a medium facing surface (hereinafter referred to as "medium
facing surface" for convenience) is polished by the processing
apparatus according to the present embodiment. During the polishing
process, the workpiece 20 is held by the processing jig with a
band-shaped protective member 21 applied to the surface of the
workpiece 20 opposite to the polished surface, i.e., the medium
facing surface. The width of the protective member 21 is greater
than the width of the workpiece 20.
[0079] The protective member 21 has appropriate elasticity. The
thickness of the protective member 21 is preferably in the range
from about 90 to 150 .mu.m. For example, a member in which an
adhesive layer is stacked on a base material may be used as the
protective member 21. For example, the material that constitutes
the base material may be an organic material such as polyvinyl
chloride (PVC), polyethylene terephthalate (PET) or a polyolefine
type material. For example, the adhesive that constitutes the
adhesive layer may be an organic adhesive such as a generally-used
acrylic adhesive.
[0080] As the protective member 21, an ultraviolet setting tape
whose adhesive layer is made of an ultraviolet (UV) setting
material may be used. Such an ultraviolet setting tape may be an
ultraviolet setting dicing tape "D-series" (a trade name)
manufactured by LINTEC Corporation, for example. The adhesive
strength of the adhesive layer of such an ultraviolet setting tape
is reduced when irradiated by an ultraviolet ray. Therefore, when
such an ultraviolet setting tape is used as the protective member
21, the protective member 21 can be easily peeled off from the
workpiece 20 without leaving a trace of the adhesive by irradiating
the protective member 21 with an ultraviolet ray.
[0081] The protective member 21 may be a thermopeeling tape whose
adhesive layer is made of a termopeeling material. For example,
such a thermopeeling tape may be "SKY SHEET" (a trade name)
manufactured by Nikka Seiko Co., Ltd. Or "REVALPHA" (a trade name)
manufactured by Nitto Denko Corporation. The adhesive strength of
the adhesive layer of such a thermopeeling tape is reduced when
heated. Therefore, when such a thermopeeling tape is used as the
protective member 21, the protective member 21 can be easily peeled
off from the workpiece 20 without leaving a trace of the adhesive
by heating the protective member 21.
[0082] The protective member 21 may be an antistatic tape whose
base contains a conductive substance and has an antistatic
function. Such antistatic tapes include "ELEGRIP E-series" (a trade
name) manufactured by TOYO CHEMICAL Co., Ltd. Through the use of
such an antistatic tape as the protective member 21 to protect
protecting the medium facing surfaces of the slider sections,
electrostatic breakdown of the slider sections in the bar such as
electrostatic breakdown of the thin-film magnetic head elements in
the bar due to human handling and so on, in particular, can be
prevented.
[0083] A dry film resist used for photolithography may be used as
the protective member 21. For example, such dry film resists
include "VANX DRY FILM PHOTORESIST U-120" (a trade name)
manufactured by Fujifilm Olin Co., Ltd. When such a dry film resist
is used as the protective member 21, the dry film resist may be
utilized as a photoresist for forming a rail section to be
described later.
[0084] As shown in FIGS. 5 and 7, the processing jig has a carrier
30 and a keeper 7. The carrier 30 has a cylindrical section 30a
having a thick cylindrical configuration and a disc section 30b in
the form of a disc formed to close the lower end of the cylindrical
section 30a. The disc section 30b has a plurality of holes 30c
which are sized to allow the workpieces 20 to pass therethrough and
to disallow the protective members 21 to pass therethrough. The
thickness of the disc section 30b is smaller than a desired
thickness of the workpieces 20 to be achieved after the process.
The workpieces 20 are inserted in the holes 30c of the disc section
30b such that the lower end faces or the surfaces to be polished
thereof protrude downward from the disc section 30b into contact
with the surface plate 3. The protective members 21 are engaged
with and stopped by regions of the disc section 30b around the
holes 30c.
[0085] The keeper 7 is in the form of a column having an outline
slightly smaller than the inner diameter of the cylindrical section
30a. The keeper 7 is inserted into the cylindrical section 30a of
the carrier 30 to hold the protective member 21 and workpiece 20,
the protective member 21 being sandwiched between the lower end
face of the keeper 7 and the disc section 30b of the carrier
30.
[0086] On the inner circumference of the cylindrical section 30a of
the carrier 30, a plurality of engaging sections 30d in the form of
hooks are provided which extend downward from the upper end thereof
and further extend in the horizontal direction. Pins 7a which
engage the engaging sections 30d of the carrier 30 are provided on
the outer circumference of the keeper 7. The keeper 7 and the
carrier 30 are coupled to each other as a result of the engagement
between the pins 7a and the engaging sections 30d.
[0087] An attachment 7b which engages the lower end of the spline
shaft 6 is provided in the middle of the upper end of the keeper 7.
On the outer circumference of the attachment 7b, a plurality of
engaging sections 7c in the form of hooks are provided which extend
downward from the upper end thereof and further extend in the
horizontal direction. Although not shown, a cylindrical section
into which the attachment 7b is inserted is provided at the lower
end of the spline shaft 6, and pins which engage the engaging
sections 7c of the attachment 7b are provided on the inner
circumference of the cylindrical section. The lower end of the
spline shaft 6 and the attachment 7b are coupled to each other as a
result of the engagement between the pins of the spline shaft 6 and
the engaging sections 7c. A load is applied to the keeper 7 by a
weight 8 through the spline shaft 6.
[0088] The carrier 30 corresponds to the first member of the
present invention, and the keeper 7 corresponds to the second
member of the present invention. The holes 30c of the carrier 30
correspond to the position regulating section of the present
invention for placing the workpieces 20 in predetermined
positions.
[0089] The processing jig made up of the above-described carrier 30
and keeper 7 is rotated as a result of rotation of the surface
plate 3, or is forced to rotate.
[0090] The processing apparatus according to the present embodiment
has a plurality of types of carriers 30 which are different from
each other in at least either the lengths or positions of holes 30c
thereof. The position (in the radial direction of carrier 30) of
the outermost ends of holes 30c is uniformly set for the plurality
of types of carriers 30. To be specific, the distance between the
center of a carrier 30 and the end of a hole 30c closest to the
circumference of the carrier 30 is the same for all of the
plurality of types of carriers 30.
[0091] FIGS. 8 through 18 are plan views showing examples of the
plurality of types of carriers 30. In those figures, the two-dot
chain lines indicate the position of the outermost ends of holes
30c uniformly set for the carriers 30 as described above. In the
present embodiment, the holes 30c are provided with four lengths
D.sub.1, D.sub.2, D.sub.3 and D.sub.4 (listed in the order of
decreasing lengths) in order to accommodate workpieces 20 having
four different lengths.
[0092] In the carrier 30 shown in FIG. 8, six holes 30c each having
the length D.sub.1 are provided in parallel with each other. In the
carrier 30 shown in FIG. 9, eight holes 30c each having the length
D.sub.2 are provided in parallel with each other. In the carrier 30
shown in FIG. 10, eight holes 30c each having the length D.sub.3
are provided in parallel with each other. In the carrier 30 shown
in FIG. 11, eight holes 30c each having the length D.sub.4 are
provided in parallel with each other.
[0093] In the carrier 30 shown in FIG. 12, three sets of holes 30c
are provided at an angle of 60.degree. to each other, each set
consisting of two holes 30c each having the length D.sub.1. In the
carrier 30 shown in FIG. 13, three sets of holes 30c are provided
at an angle of 60.degree. to each other, each set consisting of two
holes 30c each having the length D.sub.2. In the carrier 30 shown
in FIG. 14, three sets of holes 30c are provided at an angle of
60.degree. to each other, each set consisting of two holes 30c each
having the length D.sub.3. In the carrier 30 shown in FIG. 15,
three sets of holes 30c are provided at an angle of 60.degree. to
each other, each set consisting of two holes 30c each having the
length D.sub.4.
[0094] In the carrier 30 shown in FIG. 16, one each of four types
of holes 30c having the lengths D.sub.1 through D.sub.4
respectively is provided in parallel with each other on one side of
the centerline, and four holes 30c are similarly provided in
positions in a point symmetrical relationship therewith. In the
carrier 30 shown in FIG. 17, one hole 30c having the length
D.sub.2, two holes 30c each having the length D.sub.3 and one hole
30c having the length D.sub.4 are provided in parallel with each
other on one side of the centerline, and four holes 30c are
similarly provided in positions in a point symmetrical relationship
therewith. In the carrier 30 shown in FIG. 18, three sets of holes
30c are provided at an angle of 60.degree. to each other, each set
consisting of one hole 30c having the length D.sub.1 and one hole
30c having the length D.sub.2.
[0095] A description will now be made on the operation of the
processing apparatus according to the present embodiment and a
method for processing a thin-film magnetic head material
(hereinafter simply referred to as "processing method") according
to the present embodiment. The processing apparatus according to
the present embodiment performs an adjusting operation as described
below before it processes a workpiece. As shown in FIG. 2, in the
adjusting operation, the keeper 7 having a known reference
thickness is attached to the lower end of the spline shaft 6, and
the keeper 7 is put into contact with the top surface of the
surface plate 3. Next, the reference position sensor 11 detects the
position of the top surface of the reference base 13 as a reference
position, and the workpiece thickness sensor 12 detects the
position of the top surface of the keeper 7. The control portion 16
recognizes and memorizes the relative positional relationship
between the reference position and the position of the top surface
of the keeper 7 based on the information of the positions detected
by the sensors 11 and 12. The surface plate 3 may be kept
stationary or rotated when the adjusting operation is performed.
However, it is preferable to rotate the surface plate 3 for the
reason described later. The adjustment is not required to be
carried out prior to each processing operation and may be carried
out at an appropriate frequency.
[0096] For processing the workpiece, as shown in FIG. 3, the
workpiece 20 held by the keeper 7 is put into contact with the
surface plate 3, and the surface plate 3 is rotated to polish the
workpiece 20. During the processing operation, the reference
position sensor 11 detects the reference position, and the
workpiece thickness sensor 12 detects the position of the top
surface of the keeper 7. The control portion 16 recognizes the
relative positional relationship between the reference position and
the position of the top surface of the keeper 7 based on the
information of the positions detected by the sensors 11 and 12.
This positional relationship is compared with the positional
relationship that has been recognized and memorized at the
adjusting operation. The thickness of the workpiece 20 is thereby
recognized.
[0097] Steps of the processing operation will now be described with
reference to the flow chart in FIG. 19 and to FIG. 3. During the
processing operation, the workpiece 20 is first secured to the
keeper 7 (step S101). The thickness of the keeper 7 used here is
the same as that of the keeper 7 used at the adjustment and is
therefore known. The keeper 7 is then secured to the processing
apparatus as shown in FIG. 3 (step S102). Then, information on the
workpieces such as the length and the number of the workpieces 20
and processing conditions are input using the control panel 2. The
input of processing conditions includes setting of a desired
thickness of the workpiece 20 after the process. Next, an operation
of processing the workpiece 20 and an operation of recognizing the
thickness of the same are carried out (step S103). For the
processing operation, the workpiece 20 held by the keeper 7 is put
into contact with the surface plate 3, and the surface plate 3 is
rotated to polish the workpiece 20. During the processing
operation, the control portion 16 controls the driving portion 15
according to the input information and conditions and recognizes
the thickness of the workpiece 20 based on the reference position
detected by the reference position sensor 11 and the position
detected by the workpiece thickness sensor 12. Next, the control
portion 16 determines whether the thickness of the workpiece 20 has
reached the set thickness or not to determine whether to terminate
the process or not (step S104). If the process is not to be
terminated (N), the step S103 is continued. If the thickness of the
workpiece 20 has reached the set thickness and the process is to be
terminated (step S104; Y), the process by the processing apparatus
is terminated. Finally, the thickness of the workpiece is measured
and evaluated (step S105) to terminate the processing
operation.
[0098] When the sensors 11 and 12 are non-contact type sensors, the
position detection with the sensors 11 and 12 during the processing
operation may be performed continuously or intermittently. When the
sensors 11 and 12 are contact type sensors, the position detection
with the sensors 11 and 12 during the processing operation is
preferably performed intermittently to suppress the wear of the
sensors 11 and 12. When the position detection with the sensors 11
and 12 is performed intermittently, as shown in FIG. 3, the arm 5
is moved up and down to put the sensors 11 and 12 in contact with
the reference base 13 and keeper 7 only when the position detection
is carried out.
[0099] When the position detection with the sensors 11 and 12 is
performed intermittently, the cycle of detection may be shortened
stepwise as the thickness of the workpiece approaches the set
value.
[0100] When the thickness of the workpiece 20 is measured based on
the values detected by the sensors 11 and 12, the position
detection with the sensors 11 and 12 may be performed plural times
for each measurement to identify the thickness of the workpiece 20
by carrying out a calculation using a statistic technique at the
control portion 16 based on a plurality of detection values. This
makes it possible to recognize the absolute thickness of the
workpiece 20 with improved accuracy.
[0101] For example, during the rotation of the surface plate 3,
swell of the surface plate 3 and keeper 7 may cause swell in the
position of the top surface of the keeper 7. In order to prevent
the thickness of the workpiece 20 recognized based on the values
detected by the sensors 11 and 12 from changing as a result of the
swell, the thickness of the workpiece 20 may be recognized as
follows. First, the adjusting operation is performed with the
surface plate 3 rotated. At this time, signals indicating rotating
positions of the surface plate 3 are generated, and the timing of
detection with the sensors 11 and 12 is determined based on the
signals to perform the position detection with the sensors 11 and
12 at a plurality of rotating positions of the surface plate 3.
Thus, the absolute position of the top surface of the keeper 7
including swell or the relationship between the rotating positions
of the surface plates 3 and the absolute position of the top
surface of the keeper 7 is recognized. For example, the
relationship is expressed by a sine curve where the rotating
positions of the surface plate 3 are plotted along the abscissa
axis and the absolute position of the top surface of the keeper 7
is plotted along the ordinate axis. During the processing
operation, the absolute position of the top surface of the keeper 7
including swell or the relationship between the rotating position
of the surface plate 3 and the absolute position of the top surface
of the keeper 7 is similarly recognized by performing the position
detection with the sensors 11 and 12 in a plurality of rotating
positions of the surface plate 3. For example, the relationship is
also expressed by a sine curve. Then, the relationship recognized
during the adjusting operation is compared with the relationship
recognized during the processing operation, which makes it possible
to accurately recognize the absolute thickness of the workpiece 20
from which any swell component has been removed. When the
relationship recognized during the adjusting operation and the
relationship recognized during the processing operation are
compared, corresponding parts between the relationships may be
accurately identified and compared with each other by correlating
the two relationships (e.g., two sine curves) or by using other
means.
[0102] A description will now be made with reference to FIGS. 20
through 26 on a step for fabricating sliders from a wafer which is
temporarily fabricated into bars which are the workpieces 20 in the
present embodiment.
[0103] In this step, a plurality of types of blocks having widths
different from each other are cut from a disc-shaped wafer on which
a plurality of rows of slider sections each including a thin-film
magnetic head element are arranged. FIG. 20 shows an example a way
in which the blocks are cut. In this example, three types of blocks
111A, 111B and 111C are cut from a wafer 101. Referring to FIG. 20,
the rows of slider sections extend in the lateral direction, and
each of the rows is located on top or at the bottom of the adjacent
one of the rows. The width of each of the blocks 111A, 111B and
111C is the length thereof in the lateral direction of the FIG. 20.
Among the three types of blocks, the block 111A is the greatest,
the block 111B is second greatest, and the block 111C is the
smallest in width. Each of the blocks 111A, 111B and 111C includes
slider sections arranged in a plurality of rows and has a specific
width.
[0104] Next, as shown in FIG. 21, an end face of the block 111
(representing the blocks 111A, 111B and 111C) opposite to an end
face 131 where a surface to become a medium facing surface is
exposed is bonded to a processing jig 132.
[0105] Then, as shown in FIG. 22, grinding using a grinding
apparatus, lapping using a lapping apparatus 133 or the like is
carried out on the end face 131, that is, the surface to become a
medium facing surface, of the block 111 bonded to the jig 132. The
MR height and the throat height are thereby defined accurately. The
MR height is the length (height) between an end of an MR
(magnetoresistive) element located in the medium facing surface and
the other end. The throat height is the length (height) of the
magnetic pole of an induction-type electromagnetic transducer
between an end thereof located in the medium facing surface and the
other end.
[0106] Next, as shown in FIG. 23, a protective member 134 is
attached to the end face 131 in order to prevent the lapped end
face 131 from being damaged or corroded.
[0107] Next, as shown in FIG. 24, the block 111 is cut with a
cutting apparatus with the end face 131 covered with the protective
member 134, such that a row of slider sections including the end
face 131 is separated from the rest of the block 111. The row of
slider sections thus separated from the block 111 is a bar 141 made
up of the row of slider sections having received the processing.
The processing of the surface to become a medium facing surface and
cutting are repeated as long as the block 111 remains.
[0108] The protective member 134 is then cut into an appropriate
size to become a protective member 21 as shown in FIGS. 5 and 6.
The bar 141 becomes a workpiece 20 as shown in FIGS. 5 and 6. The
back surface of the bar 141 (workpiece 20) is lapped by the
processing apparatus according to the invention. Through this
lapping, the final thickness of each slider and the profile of the
medium facing surfaces are controlled.
[0109] Next, as shown in FIG. 25, a plurality of bars 141 are
aligned in rows, and a photoresist pattern for etching is formed on
the medium facing surfaces of the bars 141. The bars 141 are etched
by dry etching using the photoresist pattern. Rail sections are
thereby formed in the medium facing surfaces of the bars 141.
[0110] Next, as shown in FIG. 26, the bars 141 having the rail
sections are aligned and an IC tape is attached thereto. The bars
141 are then cut by a cutting apparatus to obtain sliders 151.
[0111] As described above, with the processing apparatus or method
according to the present embodiment, the absolute thickness of a
workpiece is recognized, and a process is automatically performed
such that the thickness of the workpiece becomes a predetermined
value. This makes it possible to automatically process the
workpiece such that it will have a desired thickness and to process
the workpiece with high accuracy.
[0112] In the present embodiment, there is provided the reference
position sensor 11 for detecting a reference position and the
workpiece thickness sensor 12 for detecting a position associated
with the thickness of a workpiece that changes as a result of a
process. The absolute thickness of the workpiece is recognized
based on information detected by both of the sensors 11 and 12.
Therefore, the present embodiment makes it possible to easily
recognize the absolute thickness of the workpiece by comparing the
information detected by the sensors 11 and 12 without any
unnecessary improvement of the accuracy of a machine control
system, which consequently makes it possible to improve processing
accuracy.
[0113] When processing time is controlled to provide a workpiece
with a desired thickness, operating efficiency is low because a
processing step and a measurement/evaluation step are repeated two
or more times. On the contrary, according to the present
embodiment, the efficiency of a processing operation can be
improved because accurate recognition of the absolute thickess of a
workpiece makes it possible to provide the workpiece with a desired
thickness at one processing step. For example, the present
embodiment makes it possible to improve the efficiency of a
processing operation by 1.5 times or more (in other words, to
reduce the time of the processing operation to 2/3or less) when
compared to the case in which the processing time is
controlled.
[0114] According to the present embodiment, since there is no need
for measuring and setting the thickness of a workpiece prior to a
process, there is no possibility of occurrence of measuring and
setting errors by an operator. Further, since the present
embodiment eliminates the need for a measurement and evaluation
step in the middle of a process, it is possible to prevent any
reduction of quality attributable to electrostatic discharge (ESD),
corrosion, etc.
[0115] According to the present embodiment, the two sensors 11 and
12 can be kept in a constant positional relationship whether the
surface plate 3 is stopped or rotated because the two sensors 11
and 12 are attached to the same arm 5. This allows a further
improvement of the accuracy of recognition of the absolute
thickness of a workpiece and makes it possible to improve
processing accuracy further.
[0116] Further, according to the present embodiment, since the back
surface of a bar can be processed while the medium facing surface
of the bar which is a workpiece 20 is covered with the protective
member 21, it is possible to prevent the medium facing surface from
being damaged or corroded.
[0117] According to the present embodiment, since the protective
member 21 is sandwiched with the carrier 30 and keeper 7 to fix a
workpiece 20 on the processing jig constituted by the carrier 30
and keeper 7, the workpiece 20 can be easily fixed on the
processing jig to facilitate automation of the processing
operation. In the present embodiment, since the attachment 7b that
engages the lower end of the spline shaft 6 is provided at the
keeper 7, the operation of coupling the spline shaft 6 and keeper 7
is facilitated, which also facilitates automation of the processing
operation.
[0118] Moreover, in the present embodiment, since the protective
member 21 having appropriate elasticity is interposed between the
keeper 7 and a workpiece 20, the workpiece 20 and the surface plate
3 can be smoothly put into contact with each other even if the
workpiece 20 is tapered because the protective member 21 absorbs
the change in the thickness of the workpiece 20. In addition, since
a greater load is applied to thicker part of the workpiece 20
through the protective member 21 compared to a thinner part, the
taper of the workpiece 20 becomes smaller as the lapping of the
workpiece 20 proceeds, which makes it possible to improve the
parallelism of the workpiece 20. Variations of the thicknesses of a
plurality of workpieces 20 fixed on a single processing jig can be
reduced for the same reason.
[0119] Since the processing jig constituted by the carrier 30 and
keeper 7 rotates on the surface plate 3, the degree of lapping of a
workpiece 20 varies depending on the fixing position of the
workpiece 20 on the processing jig. The wear of the surface plate 3
varies depending on the fixing position of the workpiece 20 on the
processing jig, and the surface plate 3 will consequently have
uneven degrees of wear depending on locations. Such unevenness
deteriorates the profile of the surface to be lapped of a workpiede
20 and consequently deteriorates the profile of the medium facing
surface that is a surface opposite to the lapped surface.
[0120] In the present embodiment, on the contrary, there are
provided a plurality of types of carriers 30 which are different
from each other in at least either the lengths or positions of the
holes 30c. The position of the outermost ends of the holes,
however, is uniformly set for the plurality of types of carriers
30. Therefore, the outermost ends of workpieces 20 draw
substantially the same circular locus on the surface plate 3 even
if the workpieces have different lengths. Consequently, the present
embodiment makes it possible to perform a lapping operation on a
plurality of types of workpieces 20 having different lengths under
substantially the same conditions and to prevent occurrence of
position-dependent differences in the degree of wear of the surface
plate 3. Consequently, the present embodiment makes it possible to
perform stable and accurate processing for a long period and to
improve the accuracy of the profile of a medium facing surface.
Further, the life of the surface plate 3 can be increased by about
1.5 times, for example.
[0121] A description will now be made with reference to FIGS. 27
through 29 on a difference in distribution of thicknesses of
workpieces before and after a process using the processing
apparatus according to the present embodiment. FIG. 27 shows an
example of distribution of the thicknesses of a plurality of
workpieces before a process using the processing apparatus
according to the present embodiment. FIG. 28 shows distribution of
the thicknesses of the same plurality of workpieces after the
process using the processing apparatus according to the embodiment.
In FIGS. 27 and 28, the ordinate axis represents the thickesses of
the workpieces, and the abscissa axis represents the number of
workpieces. In the case of a process performed according to a
conventional method in which processing time is controlled, the
distribution of the thicknesses of the workpieces after the process
is similar to that shown in FIG. 27.
[0122] FIG. 29 is an illustration showing a comparison between the
thicknesses of the plurality of workpieces before and after the
process using the processing apparatus according to the embodiment.
In FIG. 29, the ordinate axis represents the thickesses of the
workpieces, and the abscissa axis represents each of the
workpieces. In FIG. 29, the dots in the upper part represent
thicknesses before the process, and the dots in the lower part
represent thciknesses after the process. It is apparent from FIGS.
27 through 29 that the processing apparatus according to the
present embodiment can accurately process a workpiece such that the
thickness of the workpiece becomes a desired value. According to
the present embodiment, variation of thicknesses can be reduced to
about one half of that in the case wherein processing time is
controlled such that workpieces will have a desired thickness.
[0123] The present invention is not limited to the above described
embodiment and may be modified in various ways. For example, each
of the first detector and the second detector may have a plurality
of sensors so as to identify the position from an average of values
detected by the sensors.
[0124] As described above, in the apparatus or method for
processing a thin-film magnetic head material according to the
invention, a reference position is detected by the first detector;
a position associated with the thickness of the material is
detected by the second detector; and the thickness of the material
is recognized based on the positions detected by the two detectors
to control the processing machine such that the thickness of the
material becomes a predetermined value. This makes it possible to
improve the accuracy and efficiency of a polishing process on the
thin-film magnetic head material.
[0125] According to the apparatus or method of the invention, the
processing jig may hold the material having a band-shaped
protective member applied to the surface opposite to the surface to
be polished. It is thereby possible to polish the surface opposite
to the medium facing surface of the material while protecting the
medium facing surface.
[0126] According to the apparatus or method of the invention, a
plurality of types of first members may be provided as the
above-described first member, which are different from each other
in at least either the length or position of the hole thereof, the
position of the outermost end of the hole being uniformly set for
the plurality of types of first members. It is thereby possible to
perform a polishing process on a plurality of types of materials
having different lengths under substantially the same
conditions.
[0127] According to the apparatus or method of the invention, a
plurality of types of processing jigs may be provided as the
processing jig described above, each of which includes a position
regulating section for placing a material in a predetermined
position, the jigs being different from each other in at least
either the length or position of the position regulating section
thereof, and the position of the outermost end of the position
regulating section thereof being uniformly set for the plurality of
processing jigs. It is thereby possible to perform a polishing
process on a plurality of types of materials having different
lengths under substantially the same conditions.
[0128] According to the apparatus or method of the invention, the
first detector and the second detector may be attached to the same
arm. In this case, the first detector and the second detector are
kept in a constant positional relationship. This allows an
improvement of the accuracy of recognition of thickness of the
thin-film magnetic head material and makes it possible to improve
processing accuracy further.
[0129] According to the apparatus or method of the invention, the
thickness of the material may be recognized based on the result of
detection carried out plural times by the first detector and the
second detector. It is thereby possible to recognize the thickness
of the material with improved accuracy.
[0130] It is apparent from the above description that the present
invention may be carried out in various modes and modifications.
Therefore, the present invention may be carried out in modes other
than the above-described best mode for carrying out the invention
within the range of equivalence of the appended claims.
* * * * *