U.S. patent application number 11/520456 was filed with the patent office on 2007-07-19 for actuation device and method for high density hard disk drive head.
This patent application is currently assigned to KR Precision Public Company Limited. Invention is credited to Szu-Han Hu, Visit Thaveeprungsriporn, Xiao Yang.
Application Number | 20070165332 11/520456 |
Document ID | / |
Family ID | 32045319 |
Filed Date | 2007-07-19 |
United States Patent
Application |
20070165332 |
Kind Code |
A1 |
Yang; Xiao ; et al. |
July 19, 2007 |
Actuation device and method for high density hard disk drive
head
Abstract
A disk drive apparatus. The apparatus has a first drive device
and a support member coupled to the first drive device. The support
member has a tongue portion and a gimbal portion. The tongue
portion is coupled the gimbal portion. A fixed drive device is
formed within a first portion of the tongue portion. A movable
drive device is operably coupled to the fixed drive device and
formed within a second portion of the tongue portion. A read/write
head is coupled to the movable drive device. A voltage source is
coupled between the fixed drive device and the movable drive device
to cause movement of the read/write head by forming an interaction
between the fixed drive device and the movable drive device.
Inventors: |
Yang; Xiao; (Fremont,
CA) ; Thaveeprungsriporn; Visit; (Bangkok, TH)
; Hu; Szu-Han; (Bangkok, TH) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
KR Precision Public Company
Limited
Ayutthaya
CA
Magnecomp Corporation
Temecula
|
Family ID: |
32045319 |
Appl. No.: |
11/520456 |
Filed: |
September 12, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10440452 |
May 15, 2003 |
7149060 |
|
|
11520456 |
Sep 12, 2006 |
|
|
|
60415384 |
Oct 1, 2002 |
|
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|
Current U.S.
Class: |
360/265.9 ;
360/294.3; G9B/5.151; G9B/5.193; G9B/5.216 |
Current CPC
Class: |
G11B 5/596 20130101;
G11B 5/4826 20130101; G11B 5/5552 20130101 |
Class at
Publication: |
360/265.9 ;
360/294.3 |
International
Class: |
G11B 5/55 20060101
G11B005/55; G11B 21/24 20060101 G11B021/24 |
Claims
1. A disk drive apparatus, the apparatus comprising: a first drive
device; a support member coupled to the first drive device, the
support member having a tongue portion and a gimble portion, the
tongue portion being coupled the gimbal portion; a fixed drive
device formed within a first portion of the tongue portion; a
movable drive device operably coupled to the fixed drive device and
formed within a second portion of the tongue portion; a read/write
head coupled to the movable drive device; a voltage source coupled
between the fixed drive device and the movable drive device to
cause movement of the read/write head by forming an interaction
between the fixed drive device and the movable drive device.
2. The apparatus of claim 1 wherein the interaction is an
electrostatic actuation force.
3. The apparatus of claim 1 wherein the movable drive device
comprises a first comb drive coupled to a second comb drive of the
fixed drive device to cause the movement of the read/write head in
an annular manner about a fixed axis, the fixed axis being within a
center region of the movable drive device; wherein the fixed drive
device has a same thickness as a thickness of the tongue
portion.
4. The apparatus of claim 1 wherein the fixed drive device and the
movable drive device being formed from the support member as a
continuous structure.
5. The apparatus of claim 1 wherein the movable drive device being
coupled to the fixed drive device within the tongue portion through
a plurality of hinge members.
6. The apparatus of claim 1 wherein the movement is a linear
movement of the read/write head.
7. The apparatus of claim 1 wherein the tongue portion is stainless
steel.
8. The apparatus of claim 1 wherein the movement has a spatial
distance of less than one micron.
9. The apparatus of claim 1 wherein the interaction is an
electrostatic force caused between the fixed drive device and the
movable drive device using the voltage source.
10. The apparatus of claim 9 wherein the electrostatic force causes
movement of the movable drive device.
11. A method for fabricating an integrated actuating device for a
read/write head, the method comprising: providing a substrate, the
substrate having an upper surface; forming a plurality of trench
isolation regions within the substrate to define a plurality of
external drive regions; forming a plurality of movable drive
members and a plurality of fixed drive members on the substrate,
the movable drive members being operably coupled to the fixed drive
members, the movable drive members being formed around a center
region, the center region being an axis of the movable drive
members; and attaching a read/write head on the center portion of
the plurality of movable drive members.
12. The method of claim 11 wherein the forming of the plurality of
isolation regions including an etching process and a filling
process.
13. The method of claim 11 wherein the attaching is a bonding
process to bond the read/write head onto the center portion of the
substrate.
14. The method of claim 11 further comprising forming a spacer
layer overlying the center region and then attaching the read/write
head onto the center region.
15. The method of claim 11 further comprising forming a conductive
layer overlying the plurality of fixed drive member and the movable
drive members.
16. The method of claim 15 wherein the conductive layer reduces a
gap spacing between a portion of the fixed drive member and a
portion of the movable drive members.
Description
BACKGROUND OF THE INVENTION
[0001] This invention generally relates to techniques for operating
a disk drive apparatus. More particularly, the present invention
provides a method and apparatus for reading and writing information
onto a computer disk commonly called a hard disk for storing data.
Merely by way of example, the present invention is implemented
using such method and apparatus with an actuating device coupled
between a read/write head and support member for fine tuning the
read/write head onto a data track on the hard disk, but it would be
recognized that the invention has a much broader range of
applicability.
[0002] Storage of information has progressed through the years.
From the early days, primitive man stored information on walls of
caves, as well as used writings on wood such as bamboo. Since then,
people have used wood, silk, and papers as a media for writings.
Paper has been bound to form books. Information is now stored
electronically on disks, tape, and semiconductor devices. As merely
an example, some of the early disks used magnetic technology to
store bits of information in a digital manner onto the magnetic
media. One of the first disk drives was discovered in the 1950's by
International Business Machines of Armonk, N.Y.
[0003] Although such disks have been successful, there continues to
be a demand for larger storage capacity drives. Higher storage
capacity can be achieved in part by increasing an aerial density of
the disk. That is, the density increases with the number of tracks
per inch (TPI) and the number of bits per inch (BPI) on the
disk.
[0004] As track density increases, however, the data track becomes
narrower and the spacing between data tracks on the disk decreases.
It becomes increasingly difficult for the motor and servo control
system to quickly and accurately position the read/write head over
the desired track. Conventional actuator motors, such as voice coil
motors (VCM), often lack sufficient resolution and bandwidth to
effectively accommodate high track-density disks. As a result, a
high bandwidth and resolution second-stage microactuator is often
necessary to precisely position the read/write head over a selected
track of the disc.
[0005] Additionally, microactuators should also be cost effectively
manufactured. Most microactuator devices are often fabricated in
individual form, which is discrete and separate from others.
Unfortunately, microactuators are often fragile, small in size, and
difficult to handle effectively. Accordingly, complex assembly
procedures are generally required to attach individual
microactuator device elements to a suspension assembly. Such
procedures are often inefficient and increases manufacturing cost,
reduces yield, and causes longer throughput times.
[0006] Thus, there is a need for an improved high volume
manufacturing process for microactuator devices.
SUMMARY OF THE INVENTION
[0007] According to the present invention, techniques for operating
a disk drive apparatus are provided. More particularly, the present
invention provides a method and apparatus for reading and writing
information onto a computer disk commonly called a hard disk for
memory applications. Merely by way of example, the present
invention is implemented using such method and apparatus using with
an actuating device coupled between a read/write head and support
member for fine tuning the read/write head onto a data track on the
hard disk, but it would be recognized that the invention has a much
broader range of applicability.
[0008] In a specific embodiment, the invention provides an improved
disk drive apparatus. The apparatus has a first drive device (e.g.,
voice coil motor, commonly called VCM) and a support member (e.g.,
suspension) coupled to the first drive device. Preferably, the
support member is operably coupled via pivoting action to the voice
coil motor. The support member has a tongue portion and a gimbal
portion, which are formed on a larger gimbal structure. The tongue
portion is coupled the gimbal portion. That is, the larger gimbal
structure is a continuous elongated member, which includes a tongue
portion that extends within the gimbal structure. The tongue
portion is continuous with a certain portion of the gimbal
structure. Preferably, the tongue portion, which is shaped like a
"tongue," has at least three sides, which are free from attachment
to the gimbal structure, which allows for the tongue portion to
move and/or flex (e.g., pitch, roll, rotate, yaw) in
three-dimensions, e.g., three degrees of freedom, or in four
dimensions, e.g., three rotational and 1 translational.
Alternatively, the tongue may be supported by other configurations,
which do not include three sides. Further details of the tongue
portion can be found throughout the present specification and more
particularly below. A fixed drive device is formed within a first
portion of the tongue portion. Preferably, the fixed drive device
is machined (e.g., etch, stamp) into the first portion of the
tongue portion. A movable drive device is operably coupled to the
fixed drive device and formed within a second portion of the tongue
portion. Preferably, the fixed drive device and movable drive
device operate in a manner to allow the movable drive device to
rotate about an axis normal to a surface area of the tongue portion
and preferably a surface of the fixed portion of the fixed drive
device. In a specific embodiment, the fixed drive device and the
movable drive device operably couple to each other via a comb
structure configuration, which allows the movable drive device to
move relative to the fixed drive device. A read/write head is
coupled (e.g., attached, bonded, glued) to the movable drive
device. Preferably, the coupling is permanent and does not allow
the read/write head to move relative to the movable drive device.
That is, the read/write head and movable drive device operate
together. A voltage source is coupled between the fixed drive
device and the movable drive device to cause movement of the
read/write head by forming an interaction between the fixed drive
device and the movable drive device. Preferably, the voltage source
causes an electrostatic force to actuate the movable drive device
via electrostatic attractive forces.
[0009] In an alternative specific embodiment, the invention
provides a method for operating a disk drive apparatus. The method
includes applying a read/write head onto a movable disk, which is
rotated about a fixed axis. The read/write head is disposed on a
movable drive device, which is operably coupled to a fixed drive
device. The movable drive device is formed on a tongue portion of a
substrate. The method adjusts a voltage source coupled between the
fixed drive device and the movable drive device to cause movement
of the read/write head by forming an interaction between the fixed
drive device and the movable drive device.
[0010] Still further, the invention provides a method for
fabricating an integrated actuating device for a read/write head.
The method includes providing a substrate, which has an upper
surface. A plurality of trench isolation regions are formed within
the substrate to define a plurality of external drive regions. The
method also forms a plurality of movable drive members and a
plurality of fixed drive members on the substrate. The movable
drive members are operably coupled to the fixed drive members. The
movable drive members are formed around a center region, which is
an axis of the movable drive members. The method also attaches a
read/write head on the center portion of the plurality of movable
drive members.
[0011] Numerous benefits are achieved using the invention over
conventional techniques. In a specific embodiment, the present
invention can be implemented using conventional lithographic
technologies. Additionally, the invention can allow for the
read/write head to move in a rotational manner through a linear
relationship between the drive voltage and movement of the
read/write head. The invention provides a simple but elegant
design, which are relatively easy to manufacture. Here, the drive
device is integrated into the tongue portion of the gimbal
structure, where the drive device is actually formed via patterning
of the gimbal structure, which uses fewer assembly steps than
conventional techniques. The drive device has the same form factor
as the tongue portion, which allows for a smaller overall form
factor for the read/write head and gimbal assembly in certain
embodiments. Depending upon the embodiment, one or more of these
benefits may be achieved. These and other benefits are described
throughout the present specification and more particularly
below.
[0012] Various additional objects, features and advantages of the
present invention can be more fully appreciated with reference to
the detailed description and accompanying drawings that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a simplified top-view diagram of a disk drive
apparatus according to an embodiment of the present invention;
[0014] FIG. 2 is a more detailed side-view diagram of a disk drive
suspension assembly according to an embodiment of the present
invention;
[0015] FIG. 3 is a detailed diagram of the operating principle of
an electrostatic actuated comb drive according to an embodiment of
the present invention;
[0016] FIG. 4 is a three dimensional illustration of a diagram of a
gimbal with a tongue portion whereupon a comb drive actuator is
formed, and slider attachment method;
[0017] FIG. 5 is a detailed top-view diagram of an integrated comb
drive actuator formed on the gimbal substrate;
[0018] FIGS. 6 through 9 are simplified diagrams illustrating a
method according to an embodiment of the present invention;
[0019] FIG. 10 is a detailed side-view diagram of a head gimbal
assembly with integrated comb drive actuator formed on the gimbal
substrate; and
[0020] FIG. 11 is a detailed diagram of fabricating an integrated
comb drive actuator on the gimbal substrate using laser
micromachining.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0021] According to the present invention, techniques for operating
a disk drive apparatus are provided. More particularly, the present
invention provides a method and apparatus for reading and writing
information onto a computer disk commonly called a hard disk for
memory applications. Merely by way of example, the present
invention is implemented using such method and apparatus using with
an actuating device coupled between a read/write head and support
member for fine tuning the read/write head onto a data track on the
hard disk, but it would be recognized that the invention has a much
broader range of applicability.
[0022] FIG. 1 is a simplified top-view diagram 100 of a disk drive
apparatus according to an embodiment of the present invention. This
diagram is merely an example, which should not unduly limit the
scope of the claims herein. One of ordinary skill in the art would
recognize many other variations, modifications, and alternatives.
As shown, the apparatus 100 includes various features such as disk
101, which rotates about a fixed axis. The disk also includes
tracks, which are used to store information thereon. The disk
rotates at 7,200 RPM to greater than about 10,000 depending upon
the embodiment. The disk, commonly called a platter, often includes
a magnetic media such as a ferromagnetic material, but can also
include optical materials, common coated on surfaces of the disk,
which become active regions for storing digital bit information.
Overlying the disk is head gimbal assembly or HGA 103, which
operates and controls a slider 109 coupled to a read/write head.
The head gimbal assembly is coupled to suspension 107 which couples
to an arm 105. The arm is coupled to a voice coil motor or VCM,
which moves the head assembly about a pivot point in an annular
manner. The VCM can move at a frequency of up to about 1 kHz.
Preferably, for high track density, e.g. 250 k TPI, the speed is at
least 5 kHz, but can also be greater in certain embodiments.
[0023] FIG. 2 is a more detailed side-view diagram of a disk drive
arm assembly 200 according to an embodiment of the present
invention. This diagram is merely an example, which should not
unduly limit the scope of the claims herein. One of ordinary skill
in the art would recognize many other variations, modifications,
and alternatives. Like reference numerals are used in this diagram
as certain other diagrams herein, which should not be limiting. As
shown, the assembly includes suspension 107 coupled to arm 105
coupled to voice coil motor 207. The voice coil motor allows the
arm to move in a rotational manner about a region of the disk drive
platter. The voice motor coil often actuates at a frequency of less
than 1 kHz, but can be slightly more depending upon the
application. Slider 205 is coupled to another end of the
suspension, which is often the free end of the suspension. The
slider includes read/write head 203. The head is positioned over a
track on the platter 101, which is among a plurality of tracks on
the disk. Each of the tracks is spaced from each other at a
dimension of less than one half of a micron in preferred
embodiments.
[0024] Preferably, the head gimbal assembly also includes a
microactuator device 201 integrated on the trace gimbal 203 and
coupled to the slider 204. Here, the microactuator device moves the
head in a manner normal to the track. Preferably, the microactuator
device allows for movement of up to 1 micron, but is accurate to
about a few nanometers in preferred embodiments. The microactuator
can move using a frequency of 4 kHz, but can also be greater,
depending upon the application. In this embodiment, the
microactuator is `collocated` with respect to the head element 203
that is attached to the slider.
[0025] Preferably, the actuating device is comb drive fabricated on
the tongue portion of the gimbal, preferably the substrate material
is stainless steel. The comb drive actuating device is operable by
electrostatic force. The actuator device allows the read/write head
to move in very small and accurate steps, e.g., less than 1 micron,
but can also be slightly greater in certain applications.
Additionally, the fixed comb device has a thickness that is the
same as the thickness of the tongue portion, which provides a
smaller form factor than conventional techniques. Further details
of a present method for fabricating the drive device are provided
throughout the present specification and more particularly
below.
[0026] FIG. 3 is a detailed diagram of the operating principle of
an electrostatic actuated comb drive 300 according to an embodiment
of the present invention. This diagram is merely an example, which
should not unduly limit the scope of the claims herein. One of
ordinary skill in the art would recognize many other variations,
modifications, and alternatives. Like reference numerals are used
in this figure as others, but are not intended to be limiting. As
shown, when a voltage 301 is applied to a movable comb member 303
whereas a fixed comb member 305 is at a lower voltage potential
306, an electrostatic attraction force is occurred between the two
comb members that pulls the movable comb member towards to the
fixed comb member. Preferably, the fixed comber members 305 and 308
are tied to a bias voltage 306, a differential voltage 301 and 307
are applied to opposite movable comb members 303 and 309
respectively. The equal and opposite forces yield a torque moment
that rotates the moveable member of the actuator around the
rotating center 311. A symmetric pair of spring 313 couples between
the rotating center and fixed ends 315. The movement of the
moveable member causes a displacement of the spring which generates
a mechanical torque that counterbalances the electrostatic torque,
thus reaches a state of equilibrium. The displacement of the
moveable member is proportional to the differential voltage
applied. According to a specific embodiment, the drive voltage can
range from about 10 volts to 20 volts, but can be larger or smaller
depending upon the application.
[0027] FIG. 4 is a three-dimensional illustration of a diagram of a
gimbal with a tongue portion whereupon a comb drive actuator is
formed, and slider attachment method 400 according to an embodiment
of the present invention. This diagram is merely an example, which
should not unduly limit the scope of the claims herein. One of
ordinary skill in the art would recognize many other variations,
modifications, and alternatives. Like reference numerals are used
in this figure as others, but are not intended to be limiting. As
shown, the trace gimbal 401 includes a tongue portion 403. A comb
drive actuator 405 is formed on the tongue portion. The center 407
of the top face of the slider 205 is attached to the bottom face of
the rotating center of the actuator. The rotating movement of the
actuator causes a corresponding movement of the read/write head
element 203.
[0028] The slider rotates around the center or moves linearly
depending upon an embodiment of the present invention. Preferably,
the slider rotates through an angle of about 0.2 degrees, but can
also be more or less depending upon the application. The read/write
head can move about 1 micron or less based upon the angle of
movement of the slider, depending upon the application. The slider
is firmly attached to the movable drive device via glue, bonding,
or other permanent and suitable techniques.
[0029] FIG. 5 is a detailed top-view diagram of an integrated comb
drive actuator formed on the gimbal substrate 500 according to an
embodiment of the present invention. This diagram is merely an
example, which should not unduly limit the scope of the claims
herein. One of ordinary skill in the art would recognize many other
variations, modifications, and alternatives. Like reference
numerals are used in this figure as others, but are not intended to
be limiting. As shown, the gimbal 401 includes a tongue portion 403
whereupon the comb drive actuator is formed. Preferably, the gimbal
substrate material is stainless steel, but can be others such as
silicon, copper, etc. As shown, the tongue portion is coupled the
gimbal portion. That is, the larger gimbal structure is a
continuous elongated member, which includes a tongue portion that
extends within the gimbal structure. The tongue portion is
continuous with a certain portion of the gimbal structure.
Preferably, the tongue portion, which is shaped like a "tongue,"
has at least three sides, which are free from attachment to the
gimbal structure, which allows for the tongue portion to move
and/or flex (e.g., pitch, roll, rotate) in three-dimensions, e.g.,
three degrees of freedom. Alternatively, the tongue can be
supported by other devices such as springs, etc. A plurality of
comb fingers 501 is connected to a fixed common 504 which is
electrically isolated by an insulation layer 503, e.g., polyimide
or other suitable material. Similarly, the other portion of the
comb fingers is connected to a different fixed common 505 which is
electrically isolated by a different insulation layer 507.
Mechanical spring 509 couples between the center of the moveable
portion of the actuator 511 and the fixed portion of the gimbal.
Preferably, the mechanical spring provides a bias against the
direction of the comb drives, which move the drive device. The two
polarities 505 and 504 of the actuator are connected by copper
traces 513 and 515 respectively whereupon a differential voltage is
applied.
[0030] As shown in an enlarged view and cross-section A-A view, an
insulation layer 517 isolates the copper traces from the stainless
steel substrate. The contact 519 connects the copper trace to a
polarity of the actuator 505 through via 521. Of course, there can
be many other variations, alternatives, and modifications.
[0031] In a specific embodiment, the present invention provides a
method for fabricating an integrated comb drive actuator and gimbal
structure. Preferably, the method can be outlined as follows:
[0032] 1. Provide a substrate, e.g., stainless steel; [0033] 2.
Pattern (e.g., photolithography) the substrate to define isolation
region; [0034] 3. Form a layer of polyimide to a predetermined
thickness underlying a top surface of the substrate; [0035] 4. Form
a conductive layer (e.g., metal, copper, platinum) overlying the
polyimide layer to form an electrode layer; [0036] 5. Form
photoresist layer underlying the substrate; pattern the photoresist
layer to define comb drive and gimbal structure; [0037] 6. Form
comb drive and gimbal structure by etching stainless steel; [0038]
7. Pattern (e.g., photolithography) polyimide; [0039] 8.
Electroplate the comb finger structure to narrow the gap; and
[0040] 9. Perform other steps, as desired.
[0041] Further details of the method are provided using the
diagrams outlined below.
[0042] FIGS. 6 through 9 are simplified diagrams illustrating a
method 600 according to an embodiment of the present invention.
These diagrams are merely examples, which should not unduly limit
the scope of the claims herein. One of ordinary skill in the art
would recognize many other variations, modifications, and
alternatives. As shown, the method includes providing a substrate
601, e.g., stainless steel. The substrate can be made of a suitable
layer, which has flexibility and enough strength, including
stiffness. The substrate has a relatively constant thickness and
finish. As shown, the substrate has a upper surface and lower
surface.
[0043] As shown, the substrate is patterned to define the isolation
region 603, which corresponds to a region of reference numeral 507
in FIG. 5. Here, isolation region is a trench structure that has
been provided by patterning. Preferably, the trench structure has
substantially vertical sidewalls. Additionally, the trench
structure extends from the upper surface to the lower surface to
form openings in the substrate, although some embodiments many not
require such openings. The patterning process includes
photolithography and etching, which removes selected portions of
the substrate as shown. Etching can be performed using suitable
etchants such as HCI, and others. The method forms a layer of
polyimide 605 overlying a top surface of the substrate. As shown,
the polyimide also substantially fills in the etched isolation
region 607 in the substrate. Alternatively, another layer of
insulating material can be used depending upon the application.
Preferably, the polyimide is spin coated using conventional
techniques. Preferably, the polyimide forms plugs that extend from
the top surface to the bottom surface in certain embodiments.
[0044] Additionally, the insulating layer is formed overlying the
top surface of the substrate. As noted, the insulating layer can be
polyimide. Here, the polyimide is often coated to a thickness of
about 10 microns or less in a specific embodiment. As shown, the
thickness is substantially continuous and has a constant thickness
overlying the top surface. The polyimide is then cured and
patterned, which will be described in more detail below.
[0045] The polyimide is patterned to define gimbal structure 701,
referring to the next illustration in FIG. 7. Patterning often
occurs using lithography and etching processes, but can be others.
The polyimide is selectively patterned for subsequent isolation of
overlying conductive layers, which will be further described. The
method forms a conductive copper layer 703 overlying the polyimide
layer to form an electrode layer. A seed layer (e.g., Cr and Cu) is
often deposited first using sputtering followed by an
electroplating process of copper to reach a predetermined and/or
designed thickness. In this particular embodiment, the thickness of
the copper layer ranges from about 10 micrometers or less,
depending upon the embodiment. Other conductive layers or elements
can also be formed depending upon the embodiment.
[0046] The method then patterns the lower surface of the substrate
to define comb drive structures according to preferred embodiments.
A photolithography process patterns the photoresist to define the
comb drive structure 705. Referring to FIG. 8, a subsequent
stainless steel etch forms the comb structure 801, the mechanical
spring 803, and the gimbal structure 805. As shown, patterning
occurs through the thickness of the substrate in certain regions.
Additionally, certain portions of the copper traces are freed (not
shown) by a polyimide etch and other portions remain overlying the
polyimide layer. Here, the copper trace 703 in FIG. 8 corresponds
to reference numeral 513 in FIG. 5 according to a certain
embodiment.
[0047] It may assist the reader to understand the operation of the
comb drives before describing the fabrication process in more
detail. Here, the drive voltage for the comb drives is inversely
proportional to a gap 905 between the comb fingers. To lower the
drive voltage to be less than 20 volts, the gap should be few
micrometers or less, which cannot generally be achieved using
conventional technologies. Additionally, each of the comb fingers
should have a surface region, which faces a corresponding comb
finger. The surface regions between the respectively comb fingers
should have a substantially constant gap along the surface of such
regions. That is, each of the surfaces should be substantially
parallel to each other. In order to achieve such characteristics,
the method includes various process steps.
[0048] Referring to FIG. 9, the method provides a post-etch
electroplating process of the comb finger structure 903. The
electroplating process forms a coating overlying the etched comb
fingers. Such coating covers any non-uniformities and provides a
smooth finish of a desirable thickness to achieve a desirable gap
spacing. In a specific embodiment, a seed layer is nickel bearing
material is formed overlying exposed etched surfaces of the comb
fingers. The seed layer attaches firmly to the comb fibers. The
method then forms a highly conductive layer using, for example,
gold to desired thickness 901. Preferably, the gold is
electroplated, where the thickness of the gold material is
controlled to a predetermined thickness to achieve the desired gap
spacing between the comb fingers. As noted, the gap spacing is
desirably about 10 microns and less, depending upon the embodiment.
Of course, depending upon the applications, other materials may be
used. Additionally, there may be other methods to form the
conductive material overlying the comb fingers. Depending upon the
embodiment, it is not necessary to use a conductive material. Such
material may be insulating or semiconductor depending upon the
embodiment.
[0049] FIG. 10 is a detailed side-view diagram of a head gimbal
assembly with integrated comb drive actuator formed on the gimbal
substrate 1000 according to an embodiment of the present invention.
This diagram is merely an example, which should not unduly limit
the scope of the claims herein. One of ordinary skill in the art
would recognize many other variations, modifications, and
alternatives. Like reference numerals are used in this figure as
others, but are not intended to be limiting. As shown, the
head/slider 1001 is attached to the center portion of the comb
drive actuator by adhesive materials such as UV-cure epoxy or other
suitable materials. The head gimbal assembly is integrated to the
loadbeam 1005 to form a complete suspension for a Hard Disk
Drive.
[0050] FIG. 11 is a detailed diagram of fabricating an integrated
comb drive actuator on the gimbal substrate using laser
micromachining 1100 according to an embodiment of the present
invention. This diagram is merely an example, which should not
unduly limit the scope of the claims herein. One of ordinary skill
in the art would recognize many other variations, modifications,
and alternatives. Like reference numerals are used in this figure
as others, but are not intended to be limiting. As shown, a laser
generator device 1101 emits a laser beam 1005 that is focus by a
lens system 1003. The laser beam forms the comb drive structure by
ablation of the stainless steel in a predefined pattern 1107.
Depending upon the embodiment, there may be other ways of forming
the comb structures according to certain aspects of the present
invention.
[0051] One of ordinary skill in the art would recognize many other
variations, modifications, and alternatives. The above example is
merely an illustration, which should not unduly limit the scope of
the claims herein. One of ordinary skill in the art would recognize
many other variations, modifications, and alternatives. It is also
understood that the examples and embodiments described herein are
for illustrative purposes only and that various modifications or
changes in light thereof will be suggested to persons skilled in
the art and are to be included within the spirit and purview of
this application and scope of the appended claims.
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