U.S. patent application number 16/537407 was filed with the patent office on 2020-08-20 for head suspension assembly and disk apparatus.
The applicant listed for this patent is KABUSHIKI KAISHA TOSHIBA TOSHIBA ELECTRONIC DEVICES & STORAGE CORPORATION. Invention is credited to Yasuo SUZUKI.
Application Number | 20200265866 16/537407 |
Document ID | 20200265866 / US20200265866 |
Family ID | 1000004288022 |
Filed Date | 2020-08-20 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200265866 |
Kind Code |
A1 |
SUZUKI; Yasuo |
August 20, 2020 |
HEAD SUSPENSION ASSEMBLY AND DISK APPARATUS
Abstract
A head suspension assembly includes a support plate, an
interconnection member including a metal plate on the support
plate, a first insulating layer on the metal plate, a conductive
layer on the first insulating layer and forming a pair of
connection pads, and a second insulating layer on the conductive
layer, a head mounted in the interconnection member, and a
piezoelectric element electrically connected to the connection pads
and configured to displace the head when a predetermined voltage is
applied to the connection pads. At least one opening is formed in
each of the connection pads. The piezoelectric element is
electrically connected to each of the connection pads by a
conductive adhesive that is between the piezoelectric element and
each of the connection pads and filled into the opening.
Inventors: |
SUZUKI; Yasuo; (Fujisawa
Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOSHIBA
TOSHIBA ELECTRONIC DEVICES & STORAGE CORPORATION |
Tokyo
Tokyo |
|
JP
JP |
|
|
Family ID: |
1000004288022 |
Appl. No.: |
16/537407 |
Filed: |
August 9, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G11B 5/484 20130101 |
International
Class: |
G11B 5/48 20060101
G11B005/48 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 15, 2019 |
JP |
2019-025819 |
Claims
1. A head suspension assembly comprising: a support plate; an
interconnection member comprising a metal plate on the support
plate, a first insulating layer on the metal plate, a conductive
layer on the first insulating layer and forming a pair of
connection pads, and a second insulating layer on the conductive
layer; a head mounted in the interconnection member; and a
piezoelectric element electrically connected to the connection pads
and configured to displace the head when a predetermined voltage is
applied to the connection pads, wherein at least one opening is
formed in each of the connection pads, and the piezoelectric
element is electrically connected to each of the connection pads by
a conductive adhesive that is between the piezoelectric element and
each of the connection pads and filled into the opening.
2. The head suspension assembly according to claim 1, wherein the
opening in each of the connection pads penetrates the conductive
layer.
3. The head suspension assembly according to claim 2, wherein the
conductive adhesive is bonded to a surface of each of the
connection pads, an inner surface of the opening, and a part of the
first insulating layer.
4. The head suspension assembly according to claim 1, wherein a
plurality of openings is formed in each of the connection pads, and
the conductive adhesive is between the piezoelectric element and
each of the connection pads and filled into the plurality of
openings.
5. The head suspension assembly according to claim 4, wherein a
total number of the openings in one of the paired connection pads
is greater than a total number of the openings in the other of the
paired connection pads.
6. The head suspension assembly according to claim 1, wherein a
plurality of openings is formed on both sides of at least one of
the connection pads.
7. The head suspension assembly according to claim 1, wherein the
opening in at least one of the connection pads has a wavelike
shape.
8. The head suspension assembly according to claim 1, wherein the
opening in at least one of the connection pads has an H-shape.
9. The head suspension assembly according to claim 1, wherein the
pair of connection pads are arranged on one side of the
piezoelectric element.
10. The head suspension assembly according to claim 1, wherein the
opening in at least one of the connection pads penetrates the
conductive layer and the first insulating layer, and the conductive
adhesive is bonded to the surface of the one of the connection
pads, an inner surface of the opening, and a part of the metal
plate.
11. A disk apparatus comprising: a disk-like recording medium
having a recording layer; and a head suspension assembly
comprising: a support plate, an interconnection member disposed on
the support plate and comprising: a metal plate on the support
plate, a first insulating layer on the metal plate, a conductive
layer on the first insulating layer and forming a pair of
connection pads, and a second insulating layer on the conductive
layer, a head mounted in the interconnection member and configured
to read data from and write data onto the recording layer, and a
piezoelectric element electrically connected to the connection pads
and configured to displace the head when a predetermined voltage is
applied to the connection pads, wherein at least one opening is
formed in each of the connection pads, and the piezoelectric
element is electrically connected to each of the connection pads by
a conductive adhesive that is between the piezoelectric element and
each of the connection pads and filled into the opening.
12. The disk apparatus according to claim 11, wherein the opening
in each of the connection pads penetrates the conductive layer.
13. The disk apparatus according to claim 12, wherein the
conductive adhesive is bonded to a surface of each of the
connection pads, an inner surface of the opening, and a part of the
first insulating layer.
14. The disk apparatus according to claim 11, wherein a plurality
of openings is formed in each of the connection pads, and the
conductive adhesive is between the piezoelectric element and each
of the connection pads and filled into the plurality of
openings.
15. The disk apparatus according to claim 14, wherein a total
number of the openings in one of the paired connection pads is
greater than a total number of the openings in the other of the
paired connection pads.
16. The disk apparatus according to claim 11, wherein a plurality
of openings is formed on both sides of at least one of the
connection pads.
17. The disk apparatus according to claim 11, wherein the opening
in at least one of the connection pads has a wavelike shape.
18. The disk apparatus according to claim 11, wherein the opening
in at least one of the connection pads has an H-shape.
19. The disk apparatus according to claim 11, wherein the pair of
connection pads are arranged on one side of the piezoelectric
element.
20. The disk apparatus according to claim 11, wherein the opening
in at least one of the connection pads penetrates the conductive
layer and the first insulating layer, and the conductive adhesive
is bonded to the surface of the one of the connection pads, an
inner surface of the opening, and a part of the metal plate.
Description
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2019-025819, filed
Feb. 15, 2019, the entire contents of which are incorporated herein
by reference.
FIELD
[0002] Embodiments described herein relate generally to a head
suspension assembly and a disk apparatus equipped with the
same.
BACKGROUND
[0003] A disk apparatus, such as a hard disk drive (HDD), includes
a plurality of magnetic disks rotatable within a casing, a
plurality of magnetic heads each reading and writing information
from and to one of the magnetic disks, and a head actuator
supporting each magnetic head so that the magnetic head is movable
with respect to the corresponding magnetic disk.
[0004] The head actuator has a plurality of head suspension
assemblies each having a tip end portion that supports one magnetic
head. Each head suspension assembly has a base plate having one end
fixed to an arm, a load beam extending from the base plate, and a
flexure or an interconnection member provided on the load beam and
the base plate. The flexure has a displaceable gimbal portion and
this gimbal portion supports the magnetic head.
[0005] In recent years, a head suspension assembly having a
microactuator formed of a piezoelectric element has been proposed.
The piezoelectric element is mounted in the flexure. Electrodes of
the piezoelectric element are electrically and mechanically
connected to a conductor pattern, for example, conductive pads on
the flexure by, for example, a conductive adhesive.
DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is an exploded perspective view of a hard disk drive
(HDD) according to an embodiment.
[0007] FIG. 2 is a plan view of a head suspension assembly of the
HDD.
[0008] FIG. 3 is a perspective view depicting the head suspension
assembly.
[0009] FIG. 4 is a plan view depicting an enlarged tip end portion
of the head suspension assembly.
[0010] FIG. 5 is an exploded perspective view depicting pad
portions and a piezoelectric element of a flexure in the head
suspension assembly.
[0011] FIG. 6 is a plan view depicting the pad portions and the
piezoelectric element of the flexure in the head suspension
assembly.
[0012] FIG. 7 is a cross-sectional view of the pad portions and the
piezoelectric element along line A-A of FIG. 6.
[0013] FIG. 8 is a plan view depicting pad portions and a
piezoelectric element of an HDD according to a first
modification.
[0014] FIG. 9 is a plan view depicting pad portions and a
piezoelectric element of an HDD according to a second
modification.
[0015] FIG. 10 is a plan view depicting pad portions and a
piezoelectric element of an HDD according to a third
modification.
[0016] FIG. 11 is a plan view depicting pad portions and a
piezoelectric element of an HDD according to a fourth
modification.
[0017] FIGS. 12 and 13 are each a cross-sectional view of pad
portions and a piezoelectric element of an HDD according to a fifth
modification.
DETAILED DESCRIPTION
[0018] In the HDD, a thermal stress generated when the HDD receives
a heat from outside may cause a conduction failure between the
conductive pads and the conductive adhesive of the flexure. In case
of conduction failure, a function to electrically control the
piezoelectric element is impaired. Thus, it is desirable to ensure
a sufficient connection strength between each of the conductive
pads and the piezoelectric element.
[0019] Embodiments provide a head suspension assembly and a disk
apparatus that ensure a high connection strength between a
conductive pad and a piezoelectric element and that improves
reliability.
[0020] In general, according to one embodiment, a head suspension
assembly includes a support plate, an interconnection member
including a metal plate on the support plate, a first insulating
layer on the metal plate, a conductive layer on the first
insulating layer and forming a pair of connection pads, and a
second insulating layer on the conductive layer, a head mounted in
the interconnection member, and a piezoelectric element
electrically connected to the connection pads and configured to
displace the head when a predetermined voltage is applied to the
connection pads. At least one opening is formed in each of the
connection pads. The piezoelectric element is electrically
connected to each of the connection pads by a conductive adhesive
that is between the piezoelectric element and each of the
connection pads and filled into the opening..
[0021] A disk apparatus according to an embodiment will be
described hereinafter with reference to the drawings.
[0022] It is noted that the disclosure is presented by way of
example only and matters which may be changed as appropriate
without departing from the spirit of the disclosure and which could
easily be conceived of by a person skilled in the art naturally
fall within the scope of the present disclosure. Moreover, the
drawings are often depicted schematically in magnitudes, shapes,
and the like of parts, compared with actual forms for making
clearer descriptions. However, the drawings are presented by way of
example only and do not limit the reading of the present
disclosure. Furthermore, in the present specification and the
drawings, similar elements to those already described with
reference to the drawings already used are denoted by the same
reference signs and detailed descriptions thereof are often omitted
as appropriate.
Embodiment
[0023] A hard disk drive (HDD) serving as a disk apparatus
according to an embodiment will be described in detail.
[0024] FIG. 1 is an exploded perspective view of the HDD according
to the embodiment with a cover detached. As depicted in FIG. 1, the
HDD includes a rectangular casing 10. The casing 10 has a
rectangular box-type base 12 having an opening upper surface and a
top cover 14. The base 12 has a rectangular bottom wall 12a and a
side wall 12b raised along the periphery of the bottom wall 12a,
and the bottom wall 12a and the side wall 12b are formed integrally
from, for example, aluminum. The cover 14 is formed from, for
example, stainless steel and formed into a rectangular plate shape.
The cover 14 is screwed on the side wall 12b of the base 12 by a
plurality of screws 13 and seals the upper opening of the base
12.
[0025] The casing 10 includes a plurality of five magnetic disks
18, such as disk-like recording mediums, and a spindle motor 19
that supports and rotates the magnetic disks 18. The spindle motor
19 is disposed on the bottom wall 12a. Each magnetic disk 18 is
formed into a disk shape having a diameter of, for example, 95 mm
(3.5 inches) and has a magnetic recording layer on each of or one
of upper and lower surfaces thereof. The magnetic disk 18 is
coaxially fitted into a hub, not depicted, of the spindle motor 19,
clamped by a clamp spring 20, and fixed to the hub. The magnetic
disk 18 is thereby supported in parallel to the bottom wall 12a of
the base 12. Each of the plurality of magnetic disks 18 are rotated
at a predetermined revolving speed by the spindle motor 19.
[0026] While the five magnetic disks 18 are accommodated in the
casing 18 in the present embodiment, the number of the magnetic
disks 18 is not limited to five and may be increased or decreased.
Alternatively, a single magnetic disk 18 may be accommodated in the
casing 10.
[0027] The casing 10 includes a plurality of magnetic heads 17 each
recording and reproducing information in and from one magnetic disk
18 (refer to FIG. 2) and a head actuator 22 supporting these
magnetic heads 17 so that each magnetic head 17 is movable with
respect to one magnetic disk 18. Furthermore, the casing 10
includes a voice coil motor (VCM) 24 that rotates and positions the
head actuator 22, a ramp load mechanism 25 that holds any of the
magnetic heads 17 at an unloaded position apart from the
corresponding magnetic disk 18 when the magnetic head 17 moves to
an outermost circumference of the magnetic disk 18, and a board
unit 21 (e.g., a flexible printed circuit (FPC) unit) in which
electronic components such as a conversion connector are
mounted.
[0028] The head actuator 22 has an actuator block 29 incorporating
a bearing unit 28, a plurality of arms 32 extending from the
actuator block 29, and suspension assemblies 30 (often referred to
as "head gimbal assemblies (HGAs)") extending from the respective
arms 32. One magnetic head 17 is supported on a tip end portion of
each suspension assembly 30. The head actuator 22 is rotatably
supported by a pivot raised on the bottom wall 12a via the bearing
unit 28.
[0029] A printed circuit board, not depicted, is screwed on an
outer surface of the bottom wall 12a. A control unit is implemented
in the printed circuit board, and this control unit controls the
spindle motor 19 to operate and also controls the VCM 24 and the
magnetic heads 17 to operate via the board unit 21.
[0030] A configuration of the suspension assembly 30 will next be
described in detail.
[0031] FIG. 2 is a plan view of the suspension assembly and FIG. 3
is a perspective view of the suspension assembly.
[0032] As depicted in FIGS. 2 and 3, each suspension assembly 30
has a suspension 34 extending from one arm 32, and one magnetic
head 17 is attached to a tip end portion of this suspension 34. A
combination of one magnetic head 17 and one suspension assembly 30
that supports this magnetic head 17 will be referred to as a "head
suspension assembly".
[0033] The suspension 34 that functions as a support plate has a
rectangular base plate 42 formed from a metal plate at a thickness
of several hundred micrometers, and a long and thin plate
spring-like load beam 35 formed from a metal plate at a thickness
of several tens of micrometers. The load beam 35 is disposed so
that a base end portion thereof is superimposed on a tip end
portion of the base plate 42 and fixed to the base plate 42 by
welding a plurality of locations thereof. The base end portion of
the load beam 35 has a width generally identical to that of the
base plate 42. A rod-like tab 46 protrudes on a tip end of the load
beam 35.
[0034] The base plate 42 has a circular opening 42a provided in the
base end portion and an annular projection portion 43 located
around this opening 42a. The base plate 42 is fastened to a tip end
portion of the arm 32 by fitting the projection portion 43 into a
circular caulking hole, not depicted, formed in a caulking bearing
surface of the arm 32 and caulking this projection portion 43. A
base end of the base plate 42 may be fixed to a tip end of the arm
32 by laser welding, spot welding, or adhesive bonding.
[0035] The suspension assembly 30 has a long and thin strip-like
flexure 40 for transmitting recording and reproducing signals and a
driving signal for driving a pair of piezoelectric elements (for
example, PZT elements) 50 mounted in the flexure 40, and the
piezoelectric elements 50. As depicted in FIG. 2, the flexure 40
has a tip end side portion 40a that is disposed on the load beam 35
and the base plate 42, and has an extension portion 40b that
extends outward from a side edge of the base plate 42 and that
extends along a side edge of the arm 32. A connection end portion
40C located on a tip end of the extension portion 40b has a
plurality of connection pads 40f. These connection pads 40f are
connected to a main FPC of the board unit 21.
[0036] A tip end portion of the flexure 40 has a gimbal portion 36
that is located on a tip end portion of the load beam 35 and that
functions as an elastic support portion. The magnetic head 17 is
placed and fixed onto the gimbal portion 36 and is supported by the
load beam 35 via this gimbal portion 36. The pair of piezoelectric
elements 50 serving as driving elements are mounted in the gimbal
portion 36 and are located closer to the base end of the load beam
35 than the magnetic head 17.
[0037] FIG. 4 is a plan view depicting the enlarged tip end portion
of the suspension assembly 30.
[0038] As depicted in FIGS. 3 and 4, the flexure 40 has a sheet
metal 44a serving as a base and formed from stainless steel or the
like, and a strip-like stacked member 41 bonded or fixed onto the
sheet metal 44a, and has a long and thin stacked plate. The stacked
member 41 has a base insulating layer 44b most of which is fixed to
the sheet metal 44a, a conductive layer 44c that is formed on the
base insulating layer 44b and that makes up a plurality of signal
interconnections 45a, a plurality of driving interconnections 45b,
and the plurality of connection pads 40f, and a cover insulating
layer 44d that covers the conductive layer 44c to be stacked on the
base insulating layer 44b (refer to FIG. 7). As the conductive
layer 44c, a copper foil, for example, may be used. In the tip end
side portion 40a of the flexure 40, the sheet metal 44a is bonded
onto surfaces of the load beam 35 and the base plate 42 or welded
thereonto at a plurality of welding points by spot welding.
[0039] In the gimbal portion 36 of the flexure 40, the sheet metal
44a has a rectangular tongue portion 36a that is located on a tip
end side, a generally rectangular base end portion 36b that is
opposed to the tongue portion 36a across a space and that is
located on a base end side, a pair of long and thin outriggers 36c
that extend from the tongue portion 36a to the base end portion
36b, and a pair of handles 36f that protrude from both side edges
of the tongue portion 36a to both sides thereof.
[0040] The base end portion 36b is bonded onto the surface of the
load beam 35 or fixed onto the surface of the load beam 35 by spot
welding. The tongue portion 36a has a size and a shape such that
the magnetic head 17 is placed on the tongue portion 36a, and has a
generally rectangular shape, for example. The tongue portion 36a is
disposed so that a central axis in a width direction of the tongue
portion 36a matches a central axis C of the suspension 34.
Furthermore, a generally central portion of the tongue portion 36a
abuts on a dimple 48 protruding in the tip end portion of the load
beam 35. The tongue portion 36a is displaceable in various
directions by elastic deformations of the pair of outriggers 36c.
The tongue portion 36a and the magnetic head 17 can thereby
flexibly follow a surface fluctuation of the magnetic disk 18 in
rolling and pitch directions and it is possible to maintain a
minute gap between a surface of the magnetic disk 18 and the
magnetic head 17.
[0041] In the gimbal portion 36, part of the stacked member 41 of
the flexure 40 forks into two branches, which are located on both
sides of the central axis C of the suspension 34. The stacked
member 41 has a base end portion 47a fixed to the base end portion
36b of the sheet metal 44a, a tip end portion 47b bonded onto the
tongue portion 36a, a pair of strip-like first bridge portions 47c
extending from the base end portion 47a to the tip end portion 47b,
and a pair of strip-like second bridge portions 47d arranged side
by side with the first bridge portions 47c, extending from the base
end portion 47a halfway across the first bridge portions 47c, and
merging with the first bridge portions 47c. The first bridge
portions 47c are located side by side with the outriggers 36c on
both sides of the tongue portion 36a and extend along a
longitudinal direction of the load beam 35. Furthermore, the first
bridge portions 47c extend to pass on the handles 36f and crossbars
of the outriggers 36c and are partially fixed to the handles 36f
and the crossbars. Part of each first bridge portion 47c has a
mounting portion 60 in which each piezoelectric element 50 is
mounted.
[0042] The magnetic head 17 is fixed to the tongue portion 36a by
an adhesive. The magnetic head 17 is disposed so that a
longitudinal central axis thereof matches the central axis C of the
suspension 34, and a generally central portion of the magnetic head
17 is located on the dimple 48. A recording element and a
reproducing element of the magnetic head 17 are electrically joined
to a plurality of electrode pads 40d in the tip end portion 47b by
a conductive adhesive such as a solder or a silver paste. The
magnetic head 17 is thereby connected to the signal
interconnections 45a via the electrode pads 40d.
[0043] The mounting portion 60 and the piezoelectric element 50
will be described in detail.
[0044] FIG. 5 is an exploded perspective view depicting the
mounting portion and the piezoelectric element of the flexure 40,
FIG. 6 is a plan view of the mounting portion in which the
piezoelectric element is mounted, and FIG. 7 is a cross-sectional
view of the mounting portion and the piezoelectric element along
line A-A of FIG. 6.
[0045] As depicted in FIG. 5, the mounting portion 60 has a first
connection pad 70a and a second connection pad 70b each formed from
the conductive layer 44c. The first connection pad 70a and the
second connection pad 70b are continuous with the driving
interconnections 45b each formed from the conductive layer 44c. The
first connection pad 70a and the second connection pad 70b are
arranged side by side at a predetermined distance therebetween in a
direction parallel to the center axis C of the load beam 35. In the
present embodiment, the first bridge portions 47c of the flexure 40
are divided between the first connection pad 70aand the second
connection pad 70b. The first connection pad 70a and the second
connection pad 70b are thereby disposed across a space at a
predetermined length.
[0046] In the cover insulating layer 44d stacked on the conductive
layer 44c, openings 72a and 72b are provided at positions
overlapping the first connection pad 70a and the second connection
pad 70b, respectively. Most of the first connection pad 70a and
most of the second connection pad 70b are exposed to an outer
surface of the cover insulating layer 44d through the openings 72a
and 72b, respectively. As an example, the first connection pad 70a
and the second connection pad 70b are each formed into a
rectangular shape, and the openings 72a and 72b are similarly each
formed into a rectangular shape slightly smaller in dimensions than
those of the first and second connection pads 70a and 70b.
[0047] According to the present embodiment, an opening 74a is
provided in part, for example, a generally central portion of the
first connection pad 70a. In the present embodiment, the opening of
the connection pad is a through-hole that penetrates the connection
pad in a thickness direction. The opening 74a has, for example, a
rectangular shape and penetrates the first connection pad 70a. Part
of the base insulating layer 44b is exposed via the opening
74a.
[0048] An opening 74b is provided in part, for example, a central
portion of the second connection pad 70b. The opening 74b has, for
example, a rectangular shape and penetrates the second connection
pad 70b. Part of the base insulating layer 44b is exposed via the
opening 74b. In the present embodiment, the second connection pad
70b is used as a ground-side connection pad. In this case, the
opening 74b may further penetrate the base insulating layer 44b.
Part of the sheet metal 44a is thereby exposed into the opening
74b.
[0049] As an example, the piezoelectric element 50 serving as the
driving element has a piezoelectric main body 50a formed from a
piezoelectric material and formed into a flat rectangular
parallelepiped shape, and a first electrode 51a and a second
electrode 51b provided on an outer surface of the piezoelectric
main body 50a. As the piezoelectric material, lead zirconate
titanate or ceramic, for example, is used.
[0050] The first electrode 51a extends from one end portion of a
lower surface of the piezoelectric main body 50a over a side
surface of a short side and most of an upper surface of the
piezoelectric main body 50a. The second electrode 51b extends from
one end portion of the upper surface of the piezoelectric main body
50a over a side surface of the other short side and most of the
lower surface of the piezoelectric main body 50a. On the lower
surface of the piezoelectric main body 50a, one end of the first
electrode 51a is opposed to one end of the second electrode 51b at
a gap given therebetween. On the upper surface of the piezoelectric
main body 50a, the other end of the first electrode 51a is opposed
to the other end of the second electrode 51b at a gap given
therebetween.
[0051] Applying a voltage between the first electrode 51a and the
second electrode 51b causes the piezoelectric main body 50a held
between the first electrode 51a and the second electrode 51b to
expand or contract in the longitudinal direction. As an example,
the first electrode 51a is a voltage application (Vin)-side
electrode, while the second electrode 51b is a ground (GND)-side
electrode.
[0052] As depicted in FIGS. 5 to 7, the piezoelectric element 50 is
disposed on the mounting portion 60 in a state in which one end
portion of the piezoelectric main body 50a in the longitudinal
direction (i.e., the first electrode 51a) is opposed to the first
connection pad 70a and in which the other end portion thereof in
the longitudinal direction (i.e., the second electrode 51b) is
opposed to the second connection pad 70b. A conductive adhesive Ad
is filled between the first connection pad 70a and the first
electrode 51a. As the conductive adhesive Ad, a solder or a silver
paste, for example, may be used. The first electrode 51a is
electrically and mechanically connected to the first connection pad
70a by the conductive adhesive Ad. At this time, the conductive
adhesive Ad is also filled into the opening 74a of the first
connection pad 70a, and adhesively bonded to a surface of the first
connection pad 70a, an inner surface of the opening 74a, and the
base insulating layer 44b.
[0053] Likewise, the conductive adhesive Ad is filled between the
second connection pad 70b and the second electrode 51b. The second
electrode 51b is electrically and mechanically connected to the
second connection pad 70b by the conductive adhesive Ad. The
conductive adhesive Ad is also filled into the opening 74b of the
second connection pad 70b, and adhesively bonded to a surface of
the second connection pad 70b, an inner surface of the opening 74b,
and the sheet metal 44a.
[0054] A driving voltage is applied to the first electrode 51a via
the driving interconnections 45b, the first connection pad 70a, and
the conductive adhesive Ad. While the second electrode 51b is
connected to the second connection pad 70b via the conductive
adhesive Ad and is also electrically connected to the sheet metal
44a of the flexure 40, no problem occurs in a case of using the
second electrode 51b as a ground.
[0055] In the HDD configured as described above, applying the
voltage to each piezoelectric element 50 via the driving
interconnections 45b causes the piezoelectric element 50 to expand
and contract along the longitudinal direction of the piezoelectric
element 50 (i.e., the direction parallel to the central axis C of
the suspension 34). As indicated by an arrow D in FIG. 4, driving
the two piezoelectric elements 50 in inverted directions of
expansion and contraction causes the pair of first bridge portions
47c to similarly stroke in opposite directions. The first bridge
portions 47c shake the tongue portion 36a of the gimbal portion 36
and the magnetic head 17 in arrow D directions about the dimple 48
via the handles 36f. In this way, it is possible to minutely
displace the magnetic head 17 by expansion and contraction motions
of the piezoelectric elements 50. The shaking directions D of the
magnetic head 17 correspond to seek directions of the magnetic head
17 (i.e., cross-track directions) on the magnetic disk 18.
[0056] According to the present embodiment, the openings 74a and
74b are provided in at least one of the first connection pad 70a
and the second connection pad 70b of the flexure 40, and provided
herein in both of the first and second connection pads 70a and 70b.
The conductive adhesive Ad filled between the electrodes 51a and
51b of each piezoelectric element 50 and the connection pads 70a
and 70b is also filled into the openings 74a and 74b of the
connection pads 70a and 70b and adhesively bonded to the surfaces
of the connection pads 70a and 70b, the inner surfaces of the
openings 74a and 74b, and the base insulating layer 44b. This can
enlarge a contact area between the adhesive Ad and each of the
first and second connection pads 70a and 70b and improve an
adhesive strength. Furthermore, filling the adhesive Ad into the
openings 74a and 74b produces an anchor effect to further improve
the adhesive strength. Moreover, since the opening 74b penetrates
the ground-side second connection pad 70b and the base insulating
layer 44b in the ground-side second connection pad 70b, the contact
area between the inner surface of the opening 74b and the adhesive
Ad further increases and a greater anchor effect can be obtained.
Therefore, the adhesive strength of the adhesive Ad to each of the
first and second connection pads 70a and 70b is further
improved.
[0057] Enhancing the adhesive strength between each of the first
and second connection pads 70a and 70b and the conductive adhesive
Ad in this way makes it possible to prevent occurrence of a
conduction failure when the HDD receives a thermal stress from
outside and to improve electrical connection reliability and
operation reliability of the piezoelectric elements 50.
[0058] As described so far, according to the present embodiment, it
is possible to provide the head suspension assembly and the disk
apparatus that ensure a high connection strength of each
piezoelectric element 50 and that improve the reliability.
[0059] The number of openings 74a or 74b in the first and second
connection pads 70a and 70b is not limited to one and a plurality
of openings may be provided in each of the first and second
connection pads 70a and 70b. Furthermore, the shape of the openings
74a or 74b is not limited to the rectangular shape and may be
selected from among various shapes. A plurality of modifications of
the head suspension assembly will be described hereinafter. In the
following modifications, same parts as those in the embodiment
described above are denoted by the same reference signs and
detailed descriptions thereof are either omitted or simplified.
(First Modification)
[0060] FIG. 8 is a plan view depicting connection pad portions and
a piezoelectric element of a suspension assembly according to a
first modification. As depicted in FIG. 8, according to the first
modification, a plurality of, for example, three openings 74a are
formed in the first connection pad 70a. The openings 74a are each
formed into a rectangular shape. Furthermore, two openings 74b are
provided in the second connection pad 70b. In this way, providing
the plurality of openings 74a and 74b makes it possible to increase
the contact area between the conductive adhesive Ad and each of the
first and second connection pads 70a and 70b and to increase the
anchor effect. Therefore, the adhesive strength of the conductive
adhesive Ad to each of the first and second connection pads 70a and
70b is further improved.
(Second Modification)
[0061] FIG. 9 is a plan view depicting connection pad portions and
a piezoelectric element of a suspension assembly according to a
second modification. As depicted in FIG. 9, according to the second
modification, the opening 74a of the first connection pad 70a is
formed into a comb-teeth shape. In other words, a plurality of
openings 74a are formed unevenly on a pair of opposed side edges of
the first connection pad 70a.
(Third Modification)
[0062] FIG. 10 is a plan view depicting connection pad portions and
a piezoelectric element of a suspension assembly according to a
third modification. As depicted in FIG. 10, according to the third
modification, the opening 74a of the first connection pad 70a is
formed into a wavelike shape.
(Fourth Modification)
[0063] FIG. 11 is a plan view depicting connection pad portions and
a piezoelectric element of a suspension assembly according to a
fourth modification. As depicted in FIG. 11, according to the
fourth modification, two openings 74a are formed in the first
connection pad 70a and each opening 74a has a generally
H-shape.
(Fifth Modification)
[0064] FIG. 12 is a cross-sectional view of connection pads and a
piezoelectric element of an HDD according to a fifth modification.
This cross-sectional view corresponds to the cross-sectional view
shown in FIG. 7, i.e., along line A-A of FIG. 6. However, in the
fifth modification, unlike the embodiments and modifications stated
above, both connection pads 70a and 70b are arranged on one side of
the piezoelectric element 50, and the other end of piezoelectric
element 50 is simply bonded to the flexure 40 by the adhesive Ad.
In other words, the connection pads 70a and 70b, the openings 72a
and 72b, and the openings 74a and 74b, which are invisible in FIG.
12, are located on the left side of the piezoelectric element 50
(i.e., the side of the connection end portion 40C in FIG. 2).
[0065] FIG. 13 shows the two connection pads 70a and 70b viewed
from the side of the connection end portion 40C. As shown in FIG.
13, similar to the other embodiments, the connection pads 70a and
70b are connected by the electrodes 51a and 51b of the
piezoelectric element 50. However, unlike the embodiment shown in
FIG. 6, there are no gaps in the sheet metal 44a, the insulating
layer 44b, and the cover insulating layer 44d between the two
connection pads 70a and 70b. Further, insulating layers 44e and 44f
are formed on the insulating layer 44b between the openings 74a and
74b formed by the conductive layer 44c, and there is a gap between
the adhesives Ad of the two connection pads 70a and 70b. As such,
no material is filled in the gap between the adhesives Ad. This
configuration may be used when the piezoelectric element 50 is of a
film type.
[0066] In any of the first to fifth modifications, it is possible
to improve the adhesive strength between conductive adhesive Ad and
each of the first and second connection pads 70a and 70b.
[0067] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
inventions.
[0068] For example, while the pair of piezoelectric elements 50 are
each configured to be attached to the gimbal portion 36 and located
closer to the base end portion of the load beam 35 than the
magnetic head 17 in the embodiment, the configuration of the pair
of piezoelectric elements 50 is not limited to this configuration.
The pair of piezoelectric elements 50 may be, for example, disposed
on both sides in the width direction of the support portion (tongue
portion 36a) supporting the magnetic head 17 and arranged side by
side with the magnetic head 17. The number of piezoelectric
elements 50 is not limited to two and, for example, a single
piezoelectric element may be used. The shape of the first and
second connection pads 70a and 70b is not limited to the
rectangular shape and may be selected from various shapes including
an elliptical shape, a circular shape, a polygonal shape.
* * * * *