Suspension design with improved micro-actuator sensitivity and micro-actuator configuration

Abstract

A piezoelectric (PZT) actuator assembly having a fixed end and a hinged end is provided. The assembly includes a first side electrode at the hinged end and a second side electrode at the fixed end. The assembly includes a third piezoelectric layer including a top surface and a bottom surface disposed on the top surface of the second PZT layer. A fourth electrode is at least partially disposed on the top surface of the third PZT layer. The fourth electrode is connected to the second side electrode at the fixed end.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Patent Application No. 17 / 168,052, filed February 4, 2021, and further claims priority to U.S. Provisional Application No. 62 / 971,606, filed February 7, 2020, each of which is incorporated herein by reference. Technical Field

[0003] Embodiments of this disclosure relate to the field of suspension devices for disk drives. More specifically, this disclosure relates to the field of multi-layer actuator configurations for suspension devices. Background Technology

[0004] A typical disk drive unit includes a spinning disk containing magnetic storage medium patterns of 1 and 0. These patterns of 1 and 0 constitute the data stored on the disk drive. The disk is driven by a drive motor. The disk drive unit also includes a disk drive suspension to which a magnetic read / write head is mounted, with its distal end near the load beam. The "proximal" end of the suspension or load beam is the supported end, i.e., the end closest to the base plate that is forged or otherwise mounted to the actuator arm. The "distal" end of the suspension or load beam is the end opposite to the proximal end; that is, the "distal" end is the cantilever end.

[0005] The suspension is coupled to an actuator arm, which in turn is coupled to a voice coil motor. The voice coil motor causes the suspension to move in an arc to position the head slider on the correct data track on the data disk. The head slider is supported on a gimbal that allows the slider to pitch and roll, traversing the appropriate data track on the disk and allowing for variations such as disk vibration, inertial events (e.g., bumps), and irregularities in the disk surface.

[0006] Single-stage actuated disk drive suspension and dual-stage actuated (DSA) suspension are both known. In a single-stage actuated suspension, only the voice coil motor moves the suspension.

[0007] In a DSA suspension, small actuators located on the suspension move the head slider to position it on the correct data track. The actuators provide finer head slider positioning than a voice coil motor and offer higher servo bandwidth. Depending on the specific DSA suspension design, the actuators can be positioned in different locations on the suspension. Typically, the left and right actuators operate in a push-pull manner to rotate the load beam or the distal end of the load beam. Summary of the Invention

[0008] A piezoelectric (PZT) actuator assembly having a fixed end and a hinged end is provided. The assembly includes a first side electrode located at the hinged end and a second side electrode located at the fixed end. The assembly also includes a first PZT layer comprising a top surface and a bottom surface. The first electrode is at least partially disposed on the bottom surface of the first PZT layer. A second piezoelectric layer comprising the top and bottom surfaces is disposed on the top surface of the first PZT layer. The assembly further includes a second electrode, which is at least partially disposed on the bottom surface of the second PZT layer and at least partially disposed on the top surface of the first PZT layer. The second electrode is connected to the second side electrode at the fixed end.

[0009] The component also includes a third piezoelectric layer comprising a top surface and a bottom surface disposed on the top surface of the second PZT layer. A third electrode is at least partially disposed on the bottom surface of the third PZT layer and at least partially disposed on the top surface of the second PZT layer. The third electrode is connected to the first side electrode at a hinged end. A fourth electrode is at least partially disposed on the top surface of the third PZT layer. The fourth electrode is connected to the second side electrode at a fixed end.

[0010] In some embodiments, the first electrode includes a disconnected portion at a fixed end connected to the second side electrode. In some embodiments, the fourth electrode includes a disconnected portion at a hinged end connected to the first side electrode. In some embodiments, the disconnected portion at the hinged end connected to the first side electrode is 0.05 mm. The fourth electrode may be 0.25 mm with a tolerance of 25 μm. The second electrode may be 0.70 mm with a tolerance of 25 μm. The fourth electrode may be 0.75 mm with a tolerance of 25 μm.

[0011] A suspension is also provided. The suspension may include: a flexure mounted to a load beam, the flexure including one or more electrical traces; and at least one multilayer piezoelectric (PZT) microactuator coupled to at least one of the one or more electrical traces. As described above, the assembly may have a fixed end and a hinged end. The assembly includes a first side electrode located at the hinged end and a second side electrode located at the fixed end. The assembly also includes a first PZT layer including a top surface and a bottom surface. The first electrode is at least partially disposed on the bottom surface of the first PZT layer. A second piezoelectric layer including the top and bottom surfaces is disposed on the top surface of the first PZT layer. The assembly also includes a second electrode at least partially disposed on the bottom surface of the second PZT layer and at least partially disposed on the top surface of the first PZT layer. The second electrode is connected to the second side electrode at the fixed end.

[0012] The component also includes a third piezoelectric layer comprising a top surface and a bottom surface disposed on the top surface of the second PZT layer. A third electrode is at least partially disposed on the bottom surface of the third PZT layer and at least partially disposed on the top surface of the second PZT layer. The third electrode is connected to the first side electrode at a hinged end. A fourth electrode is at least partially disposed on the top surface of the third PZT layer. The fourth electrode is connected to the second side electrode at a fixed end.

[0013] The foregoing summary is not intended to represent every embodiment or aspect of this disclosure. Rather, the foregoing summary provides only examples of some novel aspects and features set forth herein. The foregoing features and advantages, as well as other features and advantages, of this disclosure will become apparent from the following detailed description of representative embodiments and modes for carrying out the invention, when taken in conjunction with the accompanying drawings and appended claims. Attached Figure Description

[0014] To describe how the advantages and features of this disclosure can be obtained, embodiments of the disclosure are described with reference to specific examples shown in the accompanying drawings. These drawings depict only exemplary aspects of embodiments of the disclosure and should not be considered as limiting its scope. These principles are described and explained with additional specificity and detail using the following drawings.

[0015] Figure 1 This is a perspective view showing a disk drive including a suspension according to an embodiment of the present disclosure;

[0016] Figure 2 This illustrates an embodiment according to the present disclosure. Figure 1 A perspective view of the suspension 10;

[0017] Figure 3 An embodiment according to this disclosure is shown. Figure 2 Cross-sectional view of the microactuator element; and

[0018] Figure 4 A cross-sectional view of an alternative microactuator element according to an embodiment of the present disclosure is shown;

[0019] Figure 5 A cross-sectional view of a microactuator element comprising two PZT layers according to an embodiment of the present disclosure is shown; and

[0020] Figure 6 A cross-sectional view of an alternative microactuator element comprising two PZT layers according to an embodiment of the present disclosure is shown. Detailed Implementation

[0021] Embodiments of the present disclosure are described with reference to the accompanying drawings, in which the same reference numerals are used throughout the drawings to denote similar or equivalent elements. These views are not drawn to scale and are provided as illustrative examples. Several aspects of the embodiments are described below with reference to exemplary applications, and are not intended to limit the scope of the disclosure. It should be understood that numerous specific details, relationships, and methods are set forth to provide a comprehensive understanding of the embodiments.

[0022] The embodiments described herein relate to multilayer microactuators that overcome problems in the current state of microactuators. For example, when the left and right microactuators act in a push-pull manner to rotate a flexure mounted on a load beam or the distal end of a flexure mounted on a load beam, both microactuators bend in the vertical direction.

[0023] Figure 1 This is a perspective view showing a disk drive 1 according to an embodiment of the present disclosure. The disk drive 1 may include a housing 2, a disk 4, a carriage 6, and a positioning motor (voice coil motor) 7. The disk 4 is rotatable about a spindle 3. The carriage 6 is rotatable about a pivot 5. The positioning motor (voice coil motor) 7 is used to actuate the carriage 6, etc. It should be understood that the housing 2 is generally sealed; for the sake of showing all its features, the housing 2 is shown without a cover.

[0024] The bracket 6 typically includes more than one bracket arm 8. A suspension 10 is mounted on the distal portion of each arm 8. A slider constituting one or more read / write heads is provided on the distal portion of the suspension 10 (see below). Figure 2 (As shown in the diagram). With each disk 4 rotating at high speed, air flows between the disk 4 and the slider 11, forming an air bearing between them. If the bracket 6 is rotated by the positioning motor 7, the suspension 10 moves radially relative to the disk 4. As a result, the slider 11 moves to the desired track on the disk 4.

[0025] Figure 2 This illustrates an embodiment according to the present disclosure. Figure 1 A perspective view of the suspension 10. The suspension 10 may be supported by a load beam 23. The suspension may include a flexure 22. The flexure 22 supports a gimbal 21. A slider constituting a read / write head is mounted on the gimbal 21. In some embodiments, for some implementations, the slider includes a magnetoresistive (MR) element capable of converting between magnetic and electrical signals. The MR element is used to access data, i.e., to write data to or read data from the disk. Figure 1 (As shown).

[0026] The gimbal 21 includes microactuator elements 31 and 32. According to some embodiments, microactuator elements 31 and 32 are formed from piezoelectric plates of lead zirconate titanate (“PZT”) or the like. Microactuator elements 31 and 32 have the function of pivoting a slider in a rocking direction via their structure. It should be understood that any configuration of the microactuator elements can be implemented herein.

[0027] The suspension 10 includes a metal base 40. In some embodiments, the metal base 40 is formed of a stainless steel sheet. The suspension 10 also includes a conductive circuit portion comprising one or more conductors, such as traces. The conductive circuit portion includes a conductor connected to the slider. The conductor may also be connected to electrodes of the microactuator elements 31 and 32.

[0028] Figure 3 An embodiment according to this disclosure is shown. Figure 2 A cross-sectional view of the microactuator element 31. Piezoelectric elements are commonly used as microactuator motors, although static electric microactuators and other types of microactuator motors can be used. Lead zirconate titanate (PZT) is a commonly used piezoelectric material, but other piezoelectric materials can also be used. In this disclosure, for simplicity, the piezoelectric device used as a microactuator may sometimes be referred to simply as "PZT" as an abbreviation. It is understood that the piezoelectric material need not be lead zirconate titanate. Therefore, as used herein, the term "PZT" can refer to any piezoelectric material or any piezoelectric device formed from any piezoelectric material.

[0029] The microactuator element 31 may be multilayered. A first electrode 131A is disposed on at least a portion of the bottom surface of the first PZT layer 131. The first electrode 131A may be connected to a second conductive adhesive (ECA) 34 at a fixed end. A disconnected portion 131B of the first electrode 131A may also be disposed on at least that portion of the bottom surface of the first PZT layer 131. The disconnected portion 131B may be connected to the first conductive adhesive (ECA) 33 at a hinged end. A second electrode 132A may be disposed between at least a portion of the first PZT layer 131 and the second PZT layer 132. A third electrode 133A may be disposed between at least a portion of the second PZT layer 132 and the third PZT layer 133. Finally, a fourth electrode 134A may be disposed on at least a portion of the top surface of the third PZT layer 133. A disconnected portion 134B of the fourth electrode 134A may be disposed on at least a portion of the top surface of the third PZT layer 133.

[0030] The common length of the first electrode 131A and the second electrode 132A can define the effective electrode length 131D. Furthermore, the common length of the third electrode 133A and the fourth electrode 134A can define the effective electrode length 133D. The fixed end refers to the head gimbal assembly 21 (…). Figure 2The leading edge of the fourth electrode 134A is shown in the figure, while the hinged end refers to the trailing edge of the head gimbal assembly 21. In some embodiments, the length of the fourth electrode 134A is 0.64 mm with a tolerance of 25 μm.

[0031] The fourth electrode 134A is connected to the first side electrode 130A at the hinge end of the microactuator element 31. The third electrode 133A is connected to the second side electrode 130B at the fixed end of the microactuator element 31. The first side electrode 130A is connected to the first ECA 33; while the second side electrode 130B is connected to the second ECA 34.

[0032] In this configuration, the tolerance of the fourth electrode 134A has a significant impact on the gimbal torsional mode of the PZT frequency response function (FRF) in the ~10.5kHz range. Different lower lengths of the fourth electrode 134A result in greater variation in the PZT FRF, particularly around 0.335mm Z-ht. In return, this large variation will affect ( Figure 1 The servo bandwidth of disk drive 1.

[0033] Figure 4 A cross-sectional view of an alternative microactuator element 71 according to an embodiment of the present disclosure is shown. The fixed end refers to the leading edge end of the universal joint 21. Figure 2 (As shown), and the hinge end refers to the trailing edge of the universal joint 21. In some embodiments, the total length of the microactuator element 71 can be 0.80 mm with a tolerance of 25 μm. The microactuator element 71 can be a multilayer PZT, wherein the first electrode 331A is disposed on at least a portion of the bottom surface of the first PZT layer 331. The first electrode 331A can be connected to the first conductive adhesive (ECA) 33 at the hinge end. The disconnected portion 331B of the first electrode 331A can also be disposed on at least a portion of the bottom surface of the first PZT layer 331. The disconnected portion 331B can be connected to the second conductive adhesive (ECA) 34 at the fixed end. The second electrode 332A can be disposed between at least a portion of the first PZT layer 331 and the second PZT layer 332.

[0034] The third electrode 333A may be disposed between at least a portion of the second PZT layer 332 and the third PZT layer 333. Finally, the fourth electrode 334A may be disposed on at least a portion of the top surface of the third PZT layer 333. A break portion 334B of the fourth electrode 334A may be disposed on at least a portion of the top surface of the third PZT layer 333. The break portion 334B may be connected to the first ECA 33 at the hinge end 33 via the first side electrode 330A. In some embodiments, the break portion 334B may be 0.05 mm with a tolerance of 25 μm. The fourth electrode 334A may be connected to the second ECA 34 at the fixed end via the second side electrode 330B. The first side electrode 330A is connected to the first ECA 33; while the second side electrode 330B is connected to the second ECA 34.

[0035] The common length of the first electrode 331A and the second electrode 332A can define the effective electrode length 331D. Furthermore, the common length of the third electrode 333A and the fourth electrode 334A can define the effective electrode length 333D. In the microactuator element 71, the fourth electrode 334A is arranged to be directly connected to the second side electrode 330B at a fixed end. The fourth electrode 334A is also relative to... Figure 3 The fourth electrode 134A is shortened to maintain a near-zero phase angle at the nominal distance (also referred to as "z-height" or Z-ht) from the substrate flange to the data disk surface. In some cases, the near-zero phase angle is 2 degrees. In some embodiments, the fourth electrode 334A may be 0.25 mm with a tolerance of 25 μm, the second electrode 332A may be 0.70 mm with a tolerance of 25 μm, and the third electrode 333A may be 0.75 mm with a tolerance of 25 μm.

[0036] Several benefits are gained by connecting electrode 334A to the second side electrode 330B at the fixed end. In some embodiments, the variation at low Z-ht is reduced from ~60° to ~40°. Another benefit is that the travel is increased from 11 nm / V to 13.6 nm / V due to the partially constrained layer structure (CLC) configuration according to some embodiments.

[0037] Figure 5A cross-sectional view of a microactuator element 81 according to an embodiment of the present disclosure is shown. The microactuator element 81 may be multilayered, wherein a first electrode 431A is disposed on at least a portion of the bottom surface of a first PZT layer 431. The first electrode 431A may be connected to a second conductive adhesive (ECA) 134 at a fixed end. A disconnected portion 431B of the first electrode 431A may also be disposed on at least a portion of the bottom surface of the first PZT layer 431. The disconnected portion 431B may be connected to the first conductive adhesive (ECA) 133 at a hinged end. A second electrode 432A may be disposed between at least a portion of the first PZT layer 431 and the second PZT layer 432. A third electrode 433A may be disposed on at least a portion of the top surface of the second PZT layer 432. A disconnected portion 433B of the third electrode 433A may be disposed on at least a portion of the top surface of the second PZT layer 432.

[0038] The common length of the first electrode 431A and the second electrode 432A can define the effective electrode length 431D. Furthermore, the common length of the third electrode 433A and the second electrode 432A can define the effective electrode length 433D. The fixed end refers to the head gimbal assembly (e.g., Figure 2 The front edge of the head gimbal assembly shown refers to the head gimbal assembly, while the hinged end refers to the rear edge of the head gimbal assembly.

[0039] The third electrode 433A and the first electrode 431A are connected to the first side electrode 430A at the hinge end of the microactuator element 81. The third electrode 433B, the second electrode 432A, and the disconnect portion 431B are connected to the second side electrode 430B at the fixed end of the microactuator element 31. The first side electrode 430A is connected to the first ECA 33; while the second side electrode 430B is connected to the second ECA 134.

[0040] Figure 6 A cross-sectional view of an alternative microactuator element 91 according to an embodiment of the present disclosure is shown. The fixed end refers to the gimbal (e.g., Figure 2 The term "universal frame 21" refers to the front edge of the universal joint, while the "hinged end" refers to the rear edge of the universal joint. In some embodiments, the total length of the microactuator element 91 may be 0.80 mm with a tolerance of 25 μm. The microactuator element 91 may be a multilayer PZT, wherein a first electrode 531A is disposed on at least a portion of the bottom surface of the first PZT layer 531. The first electrode 531A may be connected to a first conductive adhesive (ECA) 234 at a fixed end. A disconnected portion 531B of the first electrode 531A may also be disposed on at least a portion of the bottom surface of the first PZT layer 531. The disconnected portion 531B may be connected to a second conductive adhesive (ECA) 233 at a hinged end. A second electrode 532A may be disposed between at least a portion of the first PZT layer 531 and the second PZT layer 532.

[0041] The third electrode 533A may be disposed on at least a portion of the top surface of the second PZT layer 532. A disconnected portion 533B of the third electrode 533A may be disposed on at least a portion of the top surface of the second PZT layer 532. The disconnected portion 533B may be connected to the first ECA 233 at a hinged end via the first side electrode 530A. In some embodiments, the disconnected portion 533B may be 0.05 mm with a tolerance of 25 μm. The third electrode 533A may be connected to the second ECA 234 at a fixed end via the second side electrode 530B. The first side electrode 530A is connected to the first ECA 233, the second electrode 532A, and the disconnected portion 531B. The second side electrode 530B is connected to the second ECA 234.

[0042] The common length of the first electrode 531A and the second electrode 532A defines an effective electrode length 531D. Furthermore, the common length of the third electrode 533A and the second electrode 532A defines an effective electrode length 533D. In the micro-actuator element 91, the third electrode 533A is arranged to be directly connected to the second side electrode 530B at a fixed end. In some embodiments, the length of the third electrode 533A is also shortened and configured to maintain a near-zero phase angle at the nominal distance (also referred to as "z-height" or Z-ht) from the substrate flange to the data disk surface. In some cases, the near-zero phase angle is 2 degrees.

[0043] Several benefits are gained by connecting the third electrode 533A to the second side electrode 530B at the fixed end. In some embodiments, the variation at low Z-ht is reduced from ~60° to ~40°. Another benefit is that, according to some embodiments, the travel is increased from 11 nm / V to 13.6 nm / V due to the partially constrained layer structure (CLC) configuration.

[0044] This disclosure is provided to enable those skilled in the art to make or use it. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein can be applied to other variations without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the examples and designs described herein, but is to be given the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. An actuator assembly having a fixed end and a hinged end, the assembly comprising: The first side electrode is located at the hinge end; The second side electrode is located at the fixed end; The first PZT layer includes a top surface and a bottom surface; The first electrode is at least partially disposed on the bottom surface of the first PZT layer; The second PZT layer includes a top surface and a bottom surface disposed on the top surface of the first PZT layer; The second electrode is at least partially disposed on the bottom surface of the second PZT layer and at least partially disposed on the top surface of the first PZT layer, wherein the second electrode is connected to the second side electrode at the fixed end; The third PZT layer includes a top surface and a bottom surface disposed on the top surface of the second PZT layer; A third electrode, which is at least partially disposed on the bottom surface of the third PZT layer and at least partially disposed on the top surface of the second PZT layer, wherein the third electrode is connected to the first side electrode at the hinge end; and A fourth electrode, which is at least partially disposed on the top surface of the third PZT layer, is connected to the second side electrode at the fixed end. The disconnected portion of the first electrode is separated from the first electrode and is disposed along a portion of the bottom surface of the first PZT layer, and is configured to be electrically connected to the conductive adhesive at the fixed end via the second side electrode. The disconnected portion of the fourth electrode is separated from the fourth electrode and is disposed along a portion of the top surface of the third PZT layer, and is configured to be electrically connected to the conductive adhesive at the hinge end via the first side electrode, wherein the length of the disconnected portion of the fourth electrode is less than the length of the disconnected portion of the first electrode.

2. The PZT actuator assembly as claimed in claim 1, wherein, The disconnected portion at the hinge end, which is connected to the first side electrode, is 0.05 mm.

3. The PZT actuator assembly as claimed in claim 1, wherein, The fourth electrode is 0.25 mm in diameter and has a tolerance of 25 μm.

4. The PZT actuator assembly as claimed in claim 1, wherein, The second electrode is 0.70 mm in diameter and has a tolerance of 25 μm.

5. The PZT actuator assembly as claimed in claim 1, wherein, The third electrode is 0.75 mm in diameter and has a tolerance of 25 μm.

6. A suspension system, comprising: A flexure installed on a load beam, the flexure comprising one or more electrical traces; At least one multilayer PZT microactuator assembly, said at least one multilayer PZT microactuator assembly being coupled to at least one of said one or more electrical traces and having a fixed end and a hinged end, each of said multilayer PZT actuator assemblies comprising: The first side electrode is located at the hinge end; The second side electrode is located at the fixed end; The first PZT layer includes a top surface and a bottom surface; The first electrode is at least partially disposed on the bottom surface of the first PZT layer; The second PZT layer includes a top surface and a bottom surface disposed on the top surface of the first PZT layer; The second electrode is at least partially disposed on the bottom surface of the second PZT layer and at least partially disposed on the top surface of the first PZT layer, wherein the second electrode is connected to the second side electrode at the fixed end; The third PZT layer includes a top surface and a bottom surface disposed on the top surface of the second PZT layer; A third electrode, which is at least partially disposed on the bottom surface of the third PZT layer and at least partially disposed on the top surface of the second PZT layer, wherein the third electrode is connected to the first side electrode at the hinge end; and A fourth electrode, which is at least partially disposed on the top surface of the third PZT layer, is connected to the second side electrode at the fixed end. The disconnected portion of the first electrode is separated from the first electrode and is disposed along a portion of the bottom surface of the first PZT layer, and is configured to be electrically connected to the conductive adhesive at the fixed end via the second side electrode. The disconnected portion of the fourth electrode is separated from the fourth electrode and is disposed along a portion of the top surface of the third PZT layer, and is configured to be electrically connected to the conductive adhesive at the hinge end via the first side electrode, wherein the length of the disconnected portion of the fourth electrode is less than the length of the disconnected portion of the first electrode.

7. The suspension as claimed in claim 6, wherein, The disconnection portion at the hinge end connected to the first side electrode is 0.05 mm.

8. The suspension as claimed in claim 6, wherein, The fourth electrode is 0.25 mm in diameter and has a tolerance of 25 μm.

9. The suspension as claimed in claim 6, wherein, The second electrode is 0.70 mm in diameter and has a tolerance of 25 μm.

10. The suspension as claimed in claim 6, wherein, The third electrode is 0.75 mm in diameter and has a tolerance of 25 μm.

11. An actuator assembly having a fixed end and a hinged end, the assembly comprising: First side electrode; Second side electrode; The first PZT layer includes a top surface and a bottom surface; The first electrode is at least partially disposed on the bottom surface of the first PZT layer; The second PZT layer includes a top surface and a bottom surface disposed on the top surface of the first PZT layer; A second electrode, which is at least partially disposed on the bottom surface of the second PZT layer and at least partially disposed on the top surface of the first PZT layer, wherein the second electrode is connected to the second side electrode; and A third electrode, which is at least partially disposed on the top surface of the second PZT layer, is connected to the first side electrode. The disconnected portion of the first electrode is separated from the first electrode and is disposed along a portion of the bottom surface of the first PZT layer, and is configured to be electrically connected to the conductive adhesive at the hinge end via the first side electrode. The disconnected portion of the third electrode is separated from the third electrode and is disposed along a portion of the top surface of the second PZT layer, and is configured to be electrically connected to the conductive adhesive at the hinge end via the first side electrode. Wherein, the length of the disconnected portion of the third electrode is less than the length of the disconnected portion of the first electrode.

12. The PZT actuator assembly of claim 11, wherein, The disconnected portion at the hinge end, which is connected to the first side electrode, is 0.05 mm.

13. The PZT actuator assembly of claim 11, wherein, The second electrode is 0.70 mm in diameter and has a tolerance of 25 μm.

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