Actuator assembly and disk drive

Abstract

Embodiments of the present application relate to an actuator assembly and a magnetic disk device. According to an embodiment, the actuator assembly includes a first head suspension assembly having a suspension with a first face and a second face, and a piezoelectric element mounted to the suspension and joined to the suspension by a first conductive adhesive applied to the second face side, and a second head suspension assembly having a suspension with a first face and a second face, and a piezoelectric element mounted to the suspension and joined to the suspension by a second conductive adhesive applied to the second face side. The first head suspension assembly and the second head suspension assembly are arranged with the second faces of the suspensions facing each other and the piezoelectric elements facing each other. A top of the first conductive adhesive is located at a position offset in a face direction of the suspensions relative to a top of the second conductive adhesive.

Description

[0001] This application enjoys priority based on Japanese Patent Application No. 2024-215414 (filed on December 10, 2024). This application incorporates the entire contents of the basic application by reference to that basic application. Technical Field

[0002] Embodiments of the present invention relate to actuator assemblies and disk devices. Background Technology

[0003] As a disk device, for example, a hard disk drive (HDD) includes multiple disks that are rotatably disposed within a housing, multiple read / write heads that read and write information to the disks, and head actuators (actuator assemblies) that movably support the read / write heads relative to the disks.

[0004] The head actuator has an actuator block supported for rotation and multiple head suspension assemblies (sometimes called head gimbal assemblies) extending from the actuator block and supporting the magnetic head at their top ends. Each head suspension assembly has a base plate fixed at one end to an arm, a load beam extending from the base plate, a tab extending from the top of the load beam, and flexible members (wiring members) disposed on the load beam and the base plate. The flexible member has a movable gimbal portion that supports the magnetic head.

[0005] In recent years, a configuration has been proposed that utilize multiple piezoelectric elements, such as two, installed in the suspension assembly as micro-actuators. Each piezoelectric element is electrically connected to the base plate or load beam via a conductive adhesive or the like.

[0006] When multiple suspension assemblies configured as described above are installed and stacked onto the actuator arm, the conductive adhesive portions of adjacent suspension assemblies are arranged facing each other. Therefore, when multiple suspension assemblies are stacked onto the arm, elastic deformation of the base plate or load beam may occur, causing the conductive adhesives of adjacent suspension assemblies to interfere with each other, i.e., come into contact. This is particularly true in disk drives containing many disks, where the arm plates are thin and the suspension assemblies themselves are also thin. Therefore, the conductive adhesives are more likely to come into contact with each other. Summary of the Invention

[0007] According to one embodiment, the actuator assembly includes: a first head suspension assembly having a suspension having a first surface and a second surface opposite to it, and a central axis; a wiring member and a magnetic head mounted on the first surface of the suspension; and a piezoelectric element mounted on the suspension and joined to the suspension by applying a first conductive adhesive to the second surface; and a second head suspension assembly having a suspension having a first surface and a second surface opposite to it, and a central axis; a wiring member and a magnetic head mounted on the first surface of the suspension; and a piezoelectric element mounted on the suspension and joined to the suspension by applying a second conductive adhesive to the second surface. The first and second suspension assemblies are arranged such that the second surfaces of the suspensions face each other, and the piezoelectric elements face each other. The top of the first conductive adhesive is located at a position offset relative to the top of the second conductive adhesive in the surface direction of the suspension.

[0008] According to embodiments of the present invention, actuator assemblies and disk drives that prevent interference, contact, and improve reliability can be provided. Attached Figure Description

[0009] Figure 1 This is an exploded perspective view showing the substrate and top cover of the hard disk drive (HDD) according to the first embodiment.

[0010] Figure 2 This is a perspective view showing the head actuator and FPC unit of the HDD.

[0011] Figure 3 This is a schematic side view of the head actuator.

[0012] Figure 4 This is a perspective view showing the upward-facing head suspension assembly of the head actuator.

[0013] Figure 5 This is a plan view showing the head side of the upward-facing head suspension assembly.

[0014] Figure 6 This is a plan view showing the side (back side) of the upward-facing head suspension assembly opposite to the magnetic head.

[0015] Figure 7 It is along Figure 5 A cross-sectional view of the piezoelectric element portion of line AA.

[0016] Figure 8 This is a plan view showing the face of the head-side of the head suspension assembly.

[0017] Figure 9This is a schematic plan view showing the upward-facing head suspension assembly and the downward-facing head suspension assembly in an overlapping configuration.

[0018] Figure 10 This is a plan view showing the back side of the hard disk drive (HDD) of the second embodiment, opposite to the read / write head, facing the head suspension assembly.

[0019] Figure 11 This is a plan view showing the back side of the head suspension assembly in the hard disk drive (HDD) of the second embodiment, opposite to the read / write head.

[0020] Figure 12 This is a side view schematically showing a portion of the actuator assembly in the HDD of the third embodiment.

[0021] Explanation of reference numerals in the attached figures

[0022] 10…shell, 12…base, 12a…bottom wall, 12b…side wall, 17…head,

[0023] 18…Disk, 19…Spindle motor, 22…Actuator assembly,

[0024] 30…head suspension assembly,

[0025] 30d… downward-facing head suspension assembly,

[0026] 30u… upward-facing suspension assembly, 32… arm,

[0027] 38…base plate, 40…load-bearing beam, 41a, 41b…openings,

[0028] 42… Flexible component (wiring component), 50A… First piezoelectric element, 50B… Second piezoelectric element,

[0029] Ad(d), Ad(u)... conductive adhesives Detailed Implementation

[0030] Hereinafter, the disk device according to the embodiments will be described with reference to the accompanying drawings.

[0031] Furthermore, the disclosure is always just one example, and the scope of this invention naturally includes appropriate modifications that can be easily conceived by those skilled in the art while maintaining the spirit of the invention. Additionally, to make the description clearer, the drawings sometimes schematically show the size, shape, etc. of various parts compared to the actual form, but these are always just examples and do not limit the interpretation of the invention. Furthermore, in this specification and the drawings, the same reference numerals are sometimes used for the same elements as those previously described with respect to the preceding figures, and detailed descriptions are appropriately omitted.

[0032] (First Embodiment)

[0033] As a disk device, the hard disk drive (HDD) of the first embodiment will be described in detail.

[0034] Figure 1 This is an exploded perspective view of the HDD embodiment shown with the cover removed.

[0035] like Figure 1 As shown, the HDD has a rectangular housing 10. The housing 10 has a rectangular box-shaped base 12 with an opening on the upper surface, and a cover (top cover) 14. The base 12 has a rectangular bottom wall 12a and side walls 12b that rise along the periphery of the bottom wall 12a, and is formed integrally from aluminum, for example. The cover 14 is formed into a rectangular plate shape, for example, from stainless steel. The cover 14 is threadedly fastened to the side walls 12b of the base 12 by a plurality of screws 13, thereby hermetically sealing the upper opening of the base 12.

[0036] Inside the housing 10, there are multiple disks 18, for example, ten disks, which are disc-shaped recording media, and a spindle motor 19 that supports and rotates the disks 18. The spindle motor 19 is mounted on the bottom wall 12a. Each disk 18 has, for example, a substrate formed as a disc with a diameter of 95 mm (3.5 inches) and made of a non-magnetic material such as glass, and a magnetic recording layer formed on the upper and lower surfaces of the substrate. Each disk 18 is coaxially fitted with the hub of the spindle motor 19 and then clamped by a retaining spring 20. Thus, the disks 18 are supported parallel to each other at predetermined intervals and substantially parallel to the bottom wall 12a. The spindle motor 19 rotates the multiple disks 18 at a predetermined speed in the direction of arrow B. Furthermore, the number of disks 18 mounted is not limited to 10; it can be 9 or less or 10 or more.

[0037] Within the housing 10, a plurality of magnetic heads 17 are provided for recording and reproducing information on the disk 18, and an actuator assembly 22 is provided to support these magnetic heads 17 movably relative to the disk 18. Additionally, within the housing 10, a voice coil motor (VCM) 24 is provided for rotating and positioning the actuator assembly 22; a ramp loading mechanism 25 is provided for holding the magnetic heads 17 in an unloading position away from the disk 18 when they move to the outermost periphery of the disk 18; a board unit (FPC unit) 21 is provided for mounting electronic components such as a conversion connector; and a spoiler 15 is provided. The VCM 24 includes a pair of yokes 35 disposed on the bottom wall 12a and a magnet (not shown) fixed to the yokes 35. The ramp loading mechanism 25 includes a ramp 16 erected on the bottom wall 12a.

[0038] A printed circuit board 27 is threadedly fastened to the outer surface of the bottom wall 12a of the substrate 12. The printed circuit board 27 constitutes a control unit that controls the operation of the spindle motor 19 and controls the operation of the VCM 24 and the magnetic head 17 via the board unit 21.

[0039] Figure 2 This is a perspective view showing the actuator assembly. As shown, the actuator assembly 22 includes: an actuator block 29 having a through-hole 26; a bearing unit (unit bearing) 28 disposed within the through-hole 26; a plurality of arms 32, for example 11, extending from the actuator block 29; a head suspension assembly (sometimes called a head universal joint assembly: HGA) 30 mounted on each arm 32; and a magnetic head 17 supported on the head suspension assembly 30. A support shaft (pivot) 31 is erected on the bottom wall 12a of the base 12. The actuator block 29 is supported by the bearing unit 28 and is rotatable about the support shaft 31.

[0040] In this embodiment, the actuator block 29 and the 11 arms 32 are integrally formed from aluminum or the like, constituting a so-called E-block. The arms 32 are, for example, formed into elongated flat plates, extending from the actuator block 29 in a direction orthogonal to the support shaft 31. The 11 arms 32 are arranged parallel to each other with gaps between them.

[0041] The actuator assembly 22 has a support frame 33 extending from the actuator block 29 in the opposite direction to the arm 32, by which the voice coil 39, which forms part of the VCM 24, is supported. Figure 1 As shown, the voice coil 39 is located between a pair of yokes 35, one of which is fixed on the base 12, and together with these yokes 37 and the magnets fixed to either yoke, constitutes the VCM24.

[0042] like Figure 2 As shown, the actuator assembly 22 includes 20 head suspension assemblies 30 that each support a magnetic head 17. The head suspension assemblies 30 are respectively mounted on the top end 32a of each arm 32. The plurality of head suspension assemblies 30 include an upward head suspension assembly (30u) (sometimes referred to as a first head suspension assembly) supporting the magnetic head 17 upwards, and a downward head suspension assembly (30d) (sometimes referred to as a second head suspension assembly) supporting the magnetic head 17 downwards. These upward head suspension assemblies (30u) and downward head suspension assemblies (30d) are configured by changing the vertical orientation of head suspension assemblies 30 of the same construction. However, the extension direction of the flexible member 42, described later, is opposite in the upward head suspension assembly (30u) and downward head suspension assembly (30d). By stacking the assemblies in a state where one of the upward and downward head suspension assemblies is reversed, the extension direction of the flexible member is made consistent.

[0043] Figure 3This is a schematic side view showing multiple head suspension assemblies 30. In this embodiment, in Figure 2 as well as Figure 3 In this configuration, each arm 32 has a first support surface 33a formed at its top end 32a and a second support surface 33b opposite to the first support surface. A downward-facing suspension assembly 30d is mounted on the second support surface 33b of the uppermost arm 32, and an upward-facing suspension assembly 30u is mounted on the first support surface 33a of the lowermost arm 32. An upward-facing suspension assembly 30u and a downward-facing suspension assembly 30d are mounted on the respective first support surface 33a and second support surface 33b of each of the nine intermediate arms 32.

[0044] The head suspension assembly 30 has a generally rectangular base plate 38, a load beam 40 composed of slender leaf springs, and a slender strip-shaped flexible member (wiring member) 42. The flexible member 42 has a gimbal portion, described later, on which a magnetic head 17 is mounted. The base end of the base plate 38 is fixed (e.g., slotted) to the top end 32a of the arm 32. The base end of the load beam 40 is fixed to the end of the base plate 38, overlapping with the end of the base plate 38. The load beam 40 extends from the base plate 38 and tapers towards its extended end.

[0045] The base plate 38 and the load beam 40 constitute the support plate, i.e., the suspension 34. A tongue 46 protrudes from the top of the load beam 40. The tongue 46 can engage with the aforementioned ramp 16, together with the ramp 16 forming the ramp loading mechanism 25.

[0046] like Figure 2 As shown, the FPC unit 21 integrally comprises a generally rectangular base portion 21a bent in an L-shape, an elongated strip-shaped relay portion 21b extending from one side edge of the base portion 21a, and a connecting portion 21c continuously disposed with the top end of the relay portion 21b. The base portion 21a, the relay portion 21b, and the connecting portion 21c are formed of a flexible printed wiring substrate (FPC). The flexible printed wiring substrate has an insulating layer such as polyimide, a conductive layer formed on the insulating layer and on which multiple wirings and connecting pads are formed, and a protective layer covering the conductive layer.

[0047] Electronic components such as a converter connector (not shown) and multiple capacitors are mounted on the base portion 21a and electrically connected to wiring (not shown). The base portion 21a is provided on the bottom wall 12a of the base 12. The relay portion 21b extends from the side edge of the base portion 21a toward the actuator block 29 of the actuator assembly 22. The joint portion 21c provided at the extension end of the relay portion 21b is formed into a rectangle with a height and width approximately equal to the side surface (mounting surface) of the actuator block 29. The joint portion 21c is attached to the mounting surface of the actuator block 29 via a backing plate made of aluminum or the like, and is then threadedly fastened to the mounting surface by a fixing screw 72. A plurality of connecting pads are provided in the joint portion 21c. For example, a head IC (head amplifier) ​​67 is mounted in the joint portion 21c, which is connected to the connecting pads and the base portion 21a via wiring. Furthermore, a connecting terminal 68 for connecting the voice coil 39 is provided in the joint portion 21c.

[0048] Each head suspension assembly 30 has a flexible member 42 that is electrically connected to the magnetic head 17, another end that extends through a groove formed on the side edge of the arm 32 to the actuator block 29, and a connecting end (tail connecting terminal portion) 42c provided at the other end. The connecting end 42c is formed into an elongated rectangular shape. A plurality of, for example, 13 connecting terminals (connecting pads) 51 are provided at the connecting end 42c. These connecting terminals 51 are respectively connected to the wiring of the flexible member 42. That is, the plurality of wirings of the flexible member 42 extend across approximately the entire length of the flexible member 42, with one end electrically connected to the magnetic head 17 and the other end connected to the connecting terminal (connecting pad) 51.

[0049] The connection terminals 51 located at the connection ends 42c of the 20 flexible members 42 engage with the connection pads of the joint 21c and are electrically connected to the wiring of the joint 21c via the connection pads. Thus, the 20 magnetic heads 17 of the actuator assembly 22 are electrically connected to the base part 21a via the wiring of the flexible members 42, the connection ends 42c, the joint 21c of the FPC unit 21, and the relay part 21b.

[0050] With the actuator assembly 22 configured as described above assembled onto the base 12, the support shaft 31 is erected approximately parallel to the spindle of the spindle motor 19. Each disk 18 is located between the two head suspension assemblies 30. During HDD operation, the read / write heads 17 supported by the two head suspension assemblies 30 face the upper and lower surfaces of the disk 18, respectively.

[0051] Next, the composition of the head suspension assembly 30 will be described in detail.

[0052] Figure 4 This is a perspective view showing the head side of the upper suspension assembly. Figure 5 This is a plan view showing the head side of the head suspension assembly facing upwards.

[0053] like Figure 4 as well as Figure 5 As shown, the head suspension assembly 30 has a suspension 34 that functions as a support plate. The suspension 34 has a rectangular base plate 38 made of a metal plate several hundred micrometers thick, and a slender leaf spring-shaped load beam 40 made of a metal plate several tens of micrometers thick. In one example, the thickness of the base plate 38 is formed to be about 150 to 200 μm, and the thickness of the load beam 40 is formed to be about 25 to 30 μm. The base plate 38 and the load beam 40 are, for example, made of stainless steel. The upper surface of the suspension 34 is designated as the first surface S1, and the back surface of the suspension 34 is designated as the second surface S2.

[0054] The base end of the load beam 40 overlaps with the top end of the base plate 38, and the load beam 40 is fixed to the base plate 38 by welding multiple points. The width of the base end of the load beam 40 is approximately equal to the width of the base plate 38. The load beam 40 extends from the base plate 38. The load beam 40 is formed to taper towards the top, that is, its width gradually narrows from the base end toward the top end. At the top end of the load beam 40, a slender rod-shaped tongue 46 is provided.

[0055] The substrate plate 38 has a circular through hole (knock-in hole) 38a and an annular flange 38b surrounding the through hole 38a. The flange 38b extends into the through hole 38a.

[0056] On the other hand, such as Figure 4 As shown, the arm 32 has a flat first support surface 33a and a second support surface 33b formed at the top end 32a, and a circular clamping hole 33c formed through the support surfaces 33a and 33b. The first support surface 33a and the second support surface 33b face each other parallel to each other. The second surface S2 of the base plate 38 is disposed on the first support surface 33a, and the flange 38b is fitted into the clamping hole 33c. By clamping the flange 38b, the base plate 38 is securely connected to the top end 32a of the arm 32. The base plate 38 can also be fixed to the top end 32a of the arm 32 by laser welding, spot welding, or bonding.

[0057] like Figure 4 as well as Figure 5 As shown, the head suspension assembly 30 has a central axis C1 passing through the center of the through hole 38a and the central axis C1 of the tongue 46. The load beam 40 extends from the base plate 38 along the central axis C1. The direction of extension of the central axis C1 is defined as the first direction (length direction) X of the suspension assembly, and the direction orthogonal to the first direction X is defined as the second direction (width direction) Y. The direction orthogonal to both the first direction X and the second direction Y is defined as the third direction (height direction) Z. Additionally, the direction parallel to the XY plane is sometimes referred to as the surface direction.

[0058] In the region where the base plate 38 overlaps with the load beam 40, a pair of rectangular openings (notches) 41a, each functioning as an assembly part, are formed at the top end of the base plate 38. Similarly, a pair of rectangular openings (notches) 41b, each functioning as an assembly part, are formed at the base end of the load beam 40. Each opening 41a and 41b opens on both sides of the base plate 38 and the load beam 40. Each opening 41a and 41b extends in the second direction Y, opening at the side edges of the base plate 38 and the load beam 40. The pair of openings 41a are spaced apart on both sides of the central axis C1 in the second direction Y of the base plate 38. Likewise, the pair of openings 41b are spaced apart on both sides of the central axis C1 in the second direction Y of the load beam 40. Thus, the pair of openings 41a and 41b are located in an overlapping position. The first piezoelectric element (PZT element) 50A, described later, is disposed in the two openings 41a and 41b located at overlapping positions.

[0059] The head suspension assembly 30 has an elongated, strip-shaped flexible member (wiring member) 42 for transmitting recording, playback, and drive signals. The top end portion 42a of the flexible member 42 is mounted on the first surface S1 of the suspension 34. The rear half portion (extension) 42b of the flexible member 42 extends outward from the side edge of the base plate 38 and extends along the side edge of the arm 32 (see reference). Figure 2 Furthermore, the connecting end 42c located at the top of the extension 42b is connected to the joint 21c of the aforementioned FPC unit 21.

[0060] The top end of the flexible member 42 is located on the top end of the load beam 40, forming a gimbal portion 45 that functions as an elastic support. The magnetic head 17 is mounted and fixed on the gimbal portion 36 and supported on the load beam 40 via the gimbal portion 45. A pair of second piezoelectric elements 50B are mounted on the gimbal portion 45, located at the base end of the load beam 40 relative to the magnetic head 17.

[0061] The flexible member 42 has a thin metal sheet (metal plate) 44a, such as stainless steel, serving as the substrate, and a strip-shaped laminated member 44b attached or fixed to the thin metal sheet 44a, forming an elongated laminated plate. The laminated member 44b has a base insulating layer mostly fixed to the thin metal sheet 44a, a conductive layer (wiring pattern) formed on the base insulating layer and constituting multiple signal wirings and drive wirings, and a covering insulating layer covering the conductive layer and laminated on the base insulating layer. At the top end portion 42a of the flexible member 42, the thin metal sheet 44a is attached to the surface of the load beam 40 and the base plate 38, or spot-welded to the surface of the load beam 40 and the base plate 38 through multiple welding points.

[0062] At the universal joint 45, the metal sheet 44a has a rectangular tongue (support portion) 45a located at the top end, and an elongated pair of outstretched supports (connecting portions) 45b extending from the tongue 45a to the base end. The tongue 45a is shaped and sized to accommodate the magnetic head 17, for example, it is generally rectangular. In addition, the laminated member 44b has a top end portion 44c attached to the tongue 45a.

[0063] The approximate center of the tongue 45a abuts against a recess (protrusion) (not shown) protruding from the top of the load beam 40. The tongue 45a can be displaced in various orientations with the recess as a fulcrum by the elastic deformation of a pair of outriggers 45b. As a result, the tongue 45a, the top portion 44c mounted on the tongue 45a, and the read / write head 17 can flexibly follow the roll and pitch directions in response to changes in the surface of the disk 18, and maintain a small gap between the surface of the disk 18 and the read / write head 17.

[0064] The magnetic head 17 has a generally rectangular slider 17a, which is fixed to the tip portion 44c and the tongue portion 45a by an adhesive. The magnetic head 17 is configured such that its longitudinal central axis coincides with the central axis C1 of the suspension 34, and the approximate center of the magnetic head 17 is located on a recess. The recording and playback elements of the magnetic head 17 are electrically bonded to a plurality of electrode pads PT on the tip portion 44c by a conductive adhesive such as solder or silver paste. Thus, the magnetic head 17 is connected to the signal wiring W of the flexible member 42 via the electrode pads PT.

[0065] A pair of second piezoelectric elements 50B are, for example, rectangular plate-shaped thin-film piezoelectric elements (PZT elements). The second piezoelectric elements 50B are attached to the top end 44c of the flexible member 42 using an adhesive or the like. Each second piezoelectric element 50B is electrically connected to the drive wiring of the flexible member 42. The second piezoelectric elements 50B are arranged parallel to the length direction (telescopic direction) of the load beam 40. The two second piezoelectric elements 50B are arranged parallel to each other and offset from the base end of the load beam 40 on both sides of the magnetic head 17. Furthermore, the second piezoelectric elements 50B are not limited to the above arrangement; for example, they may be arranged at an angle relative to the central axis C1.

[0066] Each of the second piezoelectric elements 50B extends and retracts along the first direction X of the suspension 34 by applying a voltage. By driving these two second piezoelectric elements 50B in opposite directions of extension and retraction, the tongue 45a can be oscillated, causing the magnetic head 17 to shift. In this way, the second piezoelectric elements 50B constitute a second microactuator for fine-tuning the magnetic head 17.

[0067] Next, the configuration of the first piezoelectric element 50A will be described in detail.

[0068] Figure 6 This is a plan view showing the back (second side) of the head suspension assembly opposite to the magnetic head. Figure 7 It is along Figure 5 A cross-sectional view of the piezoelectric element section of line AA.

[0069] like Figure 6 as well as Figure 7 As shown, a pair of first piezoelectric elements 50A uses, for example, rectangular plate-shaped thin-film piezoelectric elements (PZT elements). In one example, the first piezoelectric element 50A has a piezoelectric body 50a formed into a flat cuboid shape using a piezoelectric material, and a first electrode 51a and a second electrode 51b disposed on the outer surface of the piezoelectric body 50a. Piezoelectric materials such as zinc zirconate titanate, ceramics, etc., are used.

[0070] The first electrode 51a is disposed from one end of the upper surface of the piezoelectric body 50a, extending over the side of the short side and most of the upper surface. The second electrode 51b is disposed from one end of the lower surface of the piezoelectric body 50a, extending over the side of the short side and most of the lower surface. In one example, the first electrode 51a serves as the voltage application (Vin) side electrode, and the second electrode 51b serves as the ground (GND) side electrode.

[0071] A pair of first piezoelectric elements 50A are respectively disposed within openings 41a and 41b of the suspension 34. Each first piezoelectric element 50A is arranged with its longitudinal central axis C2 approximately parallel to the central axis C1 of the suspension 34. The pair of first piezoelectric elements 50A are spaced apart and parallel to each other in the second direction Y, located on either side of the central axis C1. The spacing between the central axes C2 and C1 of each first piezoelectric element 50A is set to be equal.

[0072] like Figure 7 As shown, within openings 41a and 41b, one axial end and the other end of the first piezoelectric element 50A are fixed to the base plate 38 and the load beam 40 by a non-conductive adhesive Ad1. The first electrode 51a of the first piezoelectric element 50A protrudes upward through openings 41a and 41b. The second electrode 51b protrudes downward through openings 41a and 41b and is located approximately coplanar with the second surface S2 of the suspension 34.

[0073] like Figure 5 as well as Figure 7 As shown, an electrode pad 54 is attached to the first electrode 51a using a conductive adhesive Ad2. The electrode pad 54 is connected to the drive signal line W of the flexible member 42. Thus, the first piezoelectric element 50A is electrically connected to the drive signal line W of the flexible member 42.

[0074] like Figure 6as well as Figure 7 As shown, a plating layer 56 is formed on the top end of the substrate plate 38, on the second surface S2. For example, a gold plating layer is used for plating layer 56. The plating layer 56 is disposed between the top end of the substrate plate 38 and a pair of openings 41a, extending over the entire range of the second direction Y.

[0075] The second electrode 51b of the first piezoelectric element 50A and the plating layer 56 are electrically bonded by a conductive adhesive Ad(u). The conductive adhesive Ad(u) is dotted on the second surface S2 of the suspension 34 at the boundary between the second electrode 51b and the plating layer 56, and is applied across both the second electrode 51b and the plating layer 56. The conductive adhesive Ad(u) is in the shape of an arc with a peak position (top T) at approximately the center of the first direction X and the second direction Y. Thus, the second electrode 51b is electrically bonded to the plating layer 56 and the substrate plate 38 by the conductive adhesive Ad(u), and connected to the ground (G) via the substrate plate 38.

[0076] By applying a voltage between the first electrode 51a and the second electrode 51b, the piezoelectric body 50a sandwiched between the first electrode 51a and the second electrode 51b elongates or contracts in the length direction (first direction X). By driving the two first piezoelectric elements 50A in such a way that the directions of extension and contraction are opposite to each other, the load beam 40 can be oscillated to displace the magnetic head 17. In this way, a pair of first piezoelectric elements 50A constitutes a first microactuator for minute displacement of the magnetic head 17.

[0077] like Figure 6 As shown, when viewed in a planar orientation, the conductive adhesive Ad(u) has a generally elliptical outer contour shape. At least one of the pair of conductive adhesives Ad(u) is positioned offset relative to the central axis C2 of the first piezoelectric element 50A in a planar direction, for example, a second direction Y. More specifically, the conductive adhesive Ad(u) is configured such that its top T is positioned offset relative to the central axis C2 of the element in the second direction Y.

[0078] In this embodiment, each of the pair of conductive adhesives Ad(u) is offset relative to the central axis C2 of the component in the second direction Y. The pair of conductive adhesives Ad(u) are offset in the same direction, specifically in the second direction Y, in a direction away from the rear half (extension) 42b of the flexible member 42. The offset amount can be arbitrarily set. In the illustrated example, they are offset to a position where the periphery of the conductive adhesive Ad(u) intersects with the central axis C2 of the component. The offset direction can also be set to the opposite direction to the illustrated example, i.e., a direction closer to the rear half (extension) 42b. Furthermore, the offset direction is not limited to the second direction Y; it can be any direction intersecting the central axis C1 in the planar direction.

[0079] Figure 8 This is a plan view showing the back side (second side S2) of the head suspension assembly opposite to the magnetic head.

[0080] like Figure 8 As shown, the downward-facing suspension assembly 30d is constructed identically to the aforementioned upward-facing suspension assembly 30u, except for the following aspects. Specifically, in the downward-facing suspension assembly 30d, the rear half (extension) 42b of the flexible member 42 extends in the opposite direction to that of the upward-facing suspension assembly 30u. Furthermore, at least one of the conductive adhesive Ad(d) of the pair of first piezoelectric elements 50A is disposed at a position offset relative to the element central axis C2 in the planar direction, for example, the second direction Y. More specifically, the conductive adhesive Ad(d) is arranged such that its top T is located at a position offset relative to the element central axis C2 in the second direction Y.

[0081] In this embodiment, the two sides of a pair of conductive adhesives Ad(d) are respectively offset relative to the central axis C2 of the element in the second direction Y. The pair of conductive adhesives Ad(d) are offset in the same direction, specifically in the second direction Y, in a direction opposite to the conductive adhesive Ad(u) of the aforementioned upward-facing suspension assembly 30u, that is, in a direction close to the rear half (extension) 42b of the flexible member 42.

[0082] The offset can be set arbitrarily. In the illustrated example, it is offset to a position where the periphery of the conductive adhesive Ad(d) is connected to the central axis C2 of the component. The offset direction is preferably opposite to the offset direction of the conductive adhesive Ad(u) of the upward-facing suspension assembly 30u. Furthermore, when the conductive adhesive Ad(u) opposite to the upward-facing suspension assembly 30u is offset from the central axis C2 of the component, the conductive adhesive Ad(d) opposite to the downward-facing suspension assembly 30d can be disposed on the central axis C2 of the component.

[0083] like Figure 3 As shown, the upward-facing suspension assembly 30u, configured as described above, is mounted on the arm 32 with the second surface S2 of the base plate 38 tightly fixed to the first support surface 33a of the arm 32. The downward-facing suspension assembly 30d is mounted on the arm 32 with the second surface S2 of the base plate 38 tightly fixed to the second support surface 33b of the arm 32. Thus, the second surface S2 (the surface opposite to the magnetic head 17) of the upward-facing suspension assembly 30u and the second surface S2 of the downward-facing suspension assembly 30d face each other at a distance in the third direction Z. Furthermore, the conductive adhesive Ad(u) of the upward-facing suspension assembly 30u faces the conductive adhesive Ad(d) of the downward-facing suspension assembly 30d in the third direction.

[0084] Figure 9 This is a schematic plan view showing the upward-facing head suspension assembly and the downward-facing head suspension assembly in a stacked configuration.

[0085] As previously described, the pair of conductive adhesives Ad(u) of the upward-facing suspension assembly 30u are located offset in one direction relative to the element central axis C2 of the first piezoelectric element 50A in the second direction Y. Conversely, the pair of conductive adhesives Ad(d) of the downward-facing suspension assembly 30d are located offset in the opposite direction relative to the element central axis C2 of the first piezoelectric element 50A in the second direction Y. Therefore, as... Figure 9 As shown, when the upward-facing suspension assembly 30u and the downward-facing suspension assembly 30d are facing each other, the conductive adhesive Ad(d) and the conductive adhesive Ad(u) are not completely facing each other, but are located at a position that is offset from each other in the plane direction, specifically in the second direction Y.

[0086] Therefore, when the head suspension assembly 30 is mounted on the arm 32, or when the head suspension assembly 30 undergoes elastic deformation, the possibility of the conductive adhesives Ad(d) and Ad(u) coming into contact or interfering with each other is greatly reduced. Thus, damage to the conductive adhesive and poor connection of the piezoelectric elements can be suppressed, thereby improving the reliability of the suspension assembly and the HDD.

[0087] According to the first embodiment configured as described above, a suspension assembly and a disk drive can be provided that prevent interference and contact with conductive adhesives and improve reliability.

[0088] Furthermore, in the first embodiment described above, the conductive adhesives Ad(d) and Ad(u) are configured and offset in a non-overlapping manner in the third direction Z, but this is not a limitation; they may also partially overlap in the third direction Z. The tops T need not be facing each other. That is, as long as the tops T are offset from each other in the second direction Y, the same effect as in the first embodiment described above can be obtained.

[0089] Next, the head suspension assembly of the HDD in other embodiments will be described. In the other embodiments described below, the same reference numerals will be used for the parts that are the same as those in the first embodiment described above, and their detailed descriptions will be omitted or simplified. The focus will be on the parts that are different from those in the first embodiment.

[0090] (Second Implementation)

[0091] Figure 10 This is a plan view showing the back side (side face) of the head suspension assembly in the HDD of the second embodiment, opposite to the read / write head. Figure 11This is a plan view showing the back side of the head-facing suspension assembly in the HDD of the second embodiment, opposite to the head.

[0092] In the second embodiment, the conductive adhesive Ad, which connects the first piezoelectric element 50A to ground, is positioned differently than in the first embodiment. In the second embodiment, the other components of the head suspension assembly 30 are the same as those in the first embodiment.

[0093] like Figure 10 As shown, according to the second embodiment, a pair of conductive adhesives Ad(u) of the upper suspension assembly 30u are disposed offset in opposite directions relative to the central axis C2 of the first piezoelectric element 50A in the second direction Y. More specifically, the pair of conductive adhesives Ad(u) are each disposed such that their top T is offset relative to the central axis C2 in a direction away from the central axis C1 of the suspension 34. The offset amount can be arbitrarily set. In the illustrated example, they are offset to a position where the periphery of the conductive adhesive Ad(u) is in contact with the central axis C2 of the element.

[0094] like Figure 11 As shown, in the downward-facing suspension assembly 30d, a pair of conductive adhesives Ad(d) are offset in a direction opposite to the second direction Y relative to the element central axis C2 of the first piezoelectric element 50A, and in a direction opposite to the offset direction of the conductive adhesive Ad(u) in the upward-facing suspension assembly 30u. Specifically, the pair of conductive adhesives Ad(d) are each positioned such that their top T is offset relative to the element central axis C2 in a direction approaching the central axis C1 of the suspension 34. The offset amount can be arbitrarily set. In the illustrated example, they are offset to a position where the periphery of the conductive adhesive Ad(d) intersects with the element central axis C2.

[0095] According to the second embodiment described above, when the upward-facing head suspension assembly 30u and the downward-facing head suspension assembly 30d are facing each other, the conductive adhesive Ad(d) and the conductive adhesive Ad(u) are not completely facing each other, but are located at a position offset from each other in the planar direction, specifically in the second direction Y. Therefore, when the head suspension assembly 30 is mounted on the arm 32, or when the head suspension assembly 30 undergoes elastic deformation, the possibility of the conductive adhesives Ad(d) and Ad(u) coming into contact or interfering with each other is greatly reduced. Therefore, damage to the conductive adhesive Ad and the occurrence of poor connection of the piezoelectric element can be suppressed, thereby improving the reliability of the suspension assembly and the HDD.

[0096] (Third Implementation)

[0097] Figure 12This is a side view showing a portion of the head actuator assembly in the HDD of the third embodiment.

[0098] As shown in the figure, according to the third embodiment, the conductive adhesive Ad(u) of the upward-facing suspension assembly 30u and the conductive adhesive Ad(d) of the downward-facing suspension assembly 30d are respectively disposed on the central axis C2 of the first piezoelectric element 50A.

[0099] With the central axis C3 being the line passing through the center of the conductive adhesive Ad(u) and the center of the conductive adhesive Ad(d), the conductive adhesive Ad(u) is formed and configured such that its top T is located at a position offset relative to the central axis C3 in the first direction X. In one example, the top T is located at a position offset towards the surface approaching the tip portion 32a of the arm.

[0100] The conductive adhesive Ad(d) is formed and configured such that its top T is offset relative to the central axis C3 in the first direction X. In one example, the top T is offset in a direction away from the top end 32a of the arm, that is, in the opposite direction to the offset direction of the top T of the conductive adhesive Ad(u).

[0101] As described above, the top T of the conductive adhesive Ad(u) and the top T of the conductive adhesive Ad(d) are located offset from each other in the planar direction (here, in the first direction X) in a manner that they do not overlap in the third direction Z. Therefore, the possibility of the conductive adhesives Ad(d) and Ad(u) coming into contact or interfering with each other is greatly reduced when the head suspension assembly 30 is mounted on the arm 32 or when the head suspension assembly 30 undergoes elastic deformation. Therefore, damage to the conductive adhesive Ad and the occurrence of poor connection of the piezoelectric element can be suppressed, thereby improving the reliability of the suspension assembly and HDD.

[0102] Furthermore, in the third embodiment, the offset of the top T of the conductive adhesive Ad can be arbitrarily set. Additionally, it is not limited to either the conductive adhesives Ad(u) or Ad(d), as long as the top T of at least one of the conductive adhesives is offset in the planar direction relative to the central axis C3.

[0103] This invention is not limited to the embodiments described above, and can be embodied by modifying the constituent elements during implementation without departing from its essence. Furthermore, various inventions can be formed through appropriate combinations of the multiple constituent elements disclosed in the above embodiments. For example, several constituent elements may be deleted from all the constituent elements shown in the embodiments. Moreover, constituent elements from different embodiments may be appropriately combined.

[0104] For example, the second piezoelectric element (second microactuator) can be omitted from the head suspension assembly. The offset directions of the conductive adhesives Ad(u) and Ad(d) are not limited to the first direction X and the second direction Y, and can be set to any other arbitrary direction. The number of disks is not limited to 10, and can be increased to 11 or 12.

Claims

1. An actuator assembly comprising: A first suspension assembly includes: a suspension having a first surface, a second surface on the opposite side, and a central axis; a wiring member and a magnetic head mounted on the first surface of the suspension; and a piezoelectric element mounted on the suspension and joined to the suspension by applying a first conductive adhesive to the second surface; and The second suspension assembly includes: a suspension having a first surface and a second surface on the opposite side and a central axis; a wiring member and a magnetic head mounted on the first surface of the suspension; and a piezoelectric element mounted on the suspension and joined to the suspension by applying a second conductive adhesive to the second surface. The first head suspension assembly and the second head suspension assembly are configured such that the second surface of the suspension faces each other and the piezoelectric elements face each other, with the top of the first conductive adhesive located at a position offset relative to the top of the second conductive adhesive in the surface direction of the suspension.

2. The actuator assembly according to claim 1, The actuator assembly includes an arm having a first support surface and a second support surface facing the first support surface. A portion of the second surface of the suspension of the first head suspension assembly is fixed to the first support surface, and a portion of the second surface of the suspension of the second head suspension assembly is fixed to the second support surface.

3. The actuator assembly according to claim 1, Each of the piezoelectric elements has a central axis extending parallel to the central axis of the suspension. The top of the first conductive adhesive is located at a position offset relative to the central axis of the element in a direction away from the central axis of the suspension. The top of the second conductive adhesive is located at a position offset relative to the central axis of the element in a direction close to the central axis of the suspension.

4. The actuator assembly according to claim 1, Each of the piezoelectric elements has a central axis extending parallel to the central axis of the suspension. The first conductive adhesive is located at a position offset relative to the central axis of the component in a direction close to the central axis of the suspension. The second conductive adhesive is located at a position offset from the central axis of the element in a direction away from the central axis of the suspension.

5. The actuator assembly according to claim 1, Each of the piezoelectric elements has a central axis extending parallel to the central axis of the suspension. The top of the first conductive adhesive is located on the central axis of the element. The top of the second conductive adhesive is located on the central axis of the element and is offset relative to the top of the first conductive adhesive in the direction along the central axis of the element.

6. The actuator assembly according to claim 2, Each suspension unit includes a base plate fixed to the support surface of the arm and a load beam extending from the base plate. The first head suspension assembly has a pair of piezoelectric elements respectively disposed between the base plate and the load beam, and each piezoelectric element is bonded to the suspension by a first conductive adhesive applied to the second surface. The second head suspension assembly has a pair of piezoelectric elements respectively disposed between the base plate and the load beam, and each piezoelectric element is bonded to the suspension by a second conductive adhesive applied to the second surface side. The pair of piezoelectric elements are arranged opposite each other, and the top of the first conductive adhesive is located at a position offset relative to the top of the second conductive adhesive in the surface direction of the suspension.

7. The actuator assembly according to claim 6, The pair of piezoelectric elements each have an element central axis extending parallel to the central axis of the suspension, and are arranged at equal intervals on both sides of the central axis, sandwiching the central axis between them.

8. The actuator assembly according to claim 7, The pair of first conductive adhesives are respectively located at positions offset relative to the central axis of the element in a direction intersecting the central axis of the suspension. The pair of the second conductive adhesives are respectively located at positions offset relative to the central axis of the element in a direction opposite to the first direction.

9. The actuator assembly according to claim 7, The pair of the first conductive adhesives are respectively located at positions offset relative to the central axis of the element in a direction away from the central axis of the suspension. The pair of the second conductive adhesives are respectively located at positions offset relative to the central axis of the element in a direction close to the central axis of the suspension.

10. A disk drive, comprising: Multiple freely rotating disk-shaped magnetic recording media; and The actuator assembly of claim 1.

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