Suspension design with improved microactuator sensitivity and microactuator configuration

Abstract

A piezoelectric (PZT) actuator assembly is provided having a fixed end and a hinged end. 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 disposed on a top surface of the second PZT layer and including a top surface and a bottom surface. 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

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate to the field of disk drive suspension systems, and more particularly, to the field of multi-layer actuator structures for suspension systems. [Background technology]

[0002] A conventional disk drive unit includes a rotating magnetic disk containing a pattern of ones and zeros on a magnetic storage medium. The pattern of ones and zeros on the magnetic storage medium constitutes the data stored on the disk drive. The magnetic disk is driven by a drive motor. The disk drive unit also includes a disk drive suspension with a magnetic read / write head mounted near the distal end of a load beam. The "proximal" end of the suspension or load beam is the end that is supported, i.e., the end closest to the base plate that is swaged or otherwise attached to the actuator arm. The "distal" end of the suspension or load beam is the end opposite the proximal end, i.e., the "distal" end is a cantilevered end.

[0003] The suspension is coupled to an actuator arm, which in turn is coupled to a voice coil motor that moves the suspension in an arc to position the head slider over the correct data track on the data disk. The head slider is mounted on a gimbal that allows the slider to pitch and roll to follow the appropriate data track on the disk, accounting for variations in disk vibrations, inertial events such as collisions, and disk surface irregularities.

[0004] Both single stage actuator disk drive suspensions and dual stage actuator (DSA) suspensions are known, in which only a voice coil motor moves the suspension.

[0005] In a DSA suspension, a small actuator located on the suspension moves the head slider, positioning it over the correct data track. The actuator provides both more precise head slider positioning than a voice coil motor and higher servo bandwidth than a voice coil motor. The actuator can be located in various locations on the suspension, depending on the specific DSA suspension design. Typically, left and right actuators operate in a push-pull fashion to rotate the load beam or the distal end of the load beam. Summary of the Invention

[0006] A piezoelectric (PZT) actuator assembly is provided having a fixed end and a hinged end. The assembly includes a first side electrode at the hinged end and a second side electrode at the fixed end. The assembly includes a first PZT layer having 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 having a top surface and a bottom surface 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.

[0007] The assembly also includes a third piezoelectric layer disposed on the top surface of the second PZT layer and including a top surface and a bottom surface. A third electrode is disposed at least partially on the bottom surface of the third PZT layer and at least partially on the top surface of the second PZT layer. The third electrode is connected to the first side electrode at a hinge end. A fourth electrode is disposed at least partially on the top surface of the third PZT layer. The fourth electrode is connected to the second side electrode at a fixed end.

[0008] In some embodiments, the first electrode includes a cut portion connected to the second side electrode at a fixed end. In some embodiments, the fourth electrode includes a cut portion connected to the first side electrode at a hinge end. In some embodiments, the cut portion connected to the first side electrode at the hinge end 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.

[0009] A suspension is also provided. The suspension includes a flexure attached to a load beam, the flexure including one or more electrical traces, and one or more multilayer piezoelectric (PZT) microactuators 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 at the hinged end and a second side electrode at the fixed end. The assembly 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 a top surface and a bottom surface 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.

[0010] The assembly also includes a third piezoelectric layer disposed on the top surface of the second PZT layer and including a top surface and a bottom surface. A third electrode is disposed at least partially on the bottom surface of the third PZT layer and at least partially on the top surface of the second PZT layer. The third electrode is connected to the first side electrode at a hinge end. A fourth electrode is disposed at least partially on the top surface of the third PZT layer. The fourth electrode is connected to the second side electrode at a fixed end.

[0011] The above summary is not intended to represent each embodiment or every aspect of the present disclosure. In particular, the above summary provides only some examples of novel aspects and features described herein. These and other features and advantages of the present disclosure will be readily apparent from the following detailed description of exemplary embodiments and aspects for carrying out the invention, taken in conjunction with the accompanying drawings and the appended claims.

[0012] To explain how the advantages and features of the present disclosure are obtained, embodiments of the present disclosure will be described with reference to specific examples illustrated in the accompanying drawings. These drawings depict only exemplary aspects of embodiments of the present disclosure and therefore should not be construed as limiting its scope. The principles will be described and explained with additional specificity and detail using the following figures. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view of a disk drive including a suspension according to one embodiment of the present disclosure. [Figure 2] 2 is a perspective view of the suspension 10 of FIG. 1 according to one embodiment of the present disclosure. [Figure 3] 3 is a cross-sectional view of the microactuator element of FIG. 2 according to one embodiment of the present disclosure. [Figure 4] FIG. 10 is a cross-sectional view of another microactuator element according to an embodiment of the present disclosure. [Figure 5] FIG. 2 is a cross-sectional view of a microactuator element including two PZT layers according to one embodiment of the present disclosure. [Figure 6] FIG. 10 is a cross-sectional view of another microactuator element including two PZT layers according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] Embodiments of the present disclosure are described with reference to the accompanying drawings, in which like reference numerals are used throughout to indicate similar or equivalent elements. The figures are not drawn to scale and are provided as exemplary illustrations. Several aspects of the embodiments are described below with reference to exemplary applications that 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 thorough understanding of the embodiments.

[0015] Embodiments described herein are directed to a multi-layer microactuator that overcomes problems with current microactuators, for example, when left and right microactuators are operated in a push-pull manner to rotate a flexure attached to a load beam or the distal end of a flexure attached to a load beam, both microactuators bend vertically.

[0016] FIG. 1 is a perspective view showing a disk drive 1 according to one embodiment of the present disclosure. The disk drive 1 may include a case 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 mounted to drive the carriage 6, etc. It should be understood that the case 2 is normally sealed. The case 2 is shown without a cover to show all the features therein.

[0017] The carriage 6 typically includes two or more carriage arms 8. A suspension 10 is attached to the tip of each arm 8. A slider (described below in FIG. 2) constituting one or more read / write heads is provided at the tip of the suspension 10. When each disk 4 is rotating at high speed, air flows between the disk 4 and the slider 11, forming an air bearing between the disk and the slider 11. When the positioning motor 7 rotates the carriage 6, the suspension 10 moves radially relative to the disk 4. This moves the slider 11 to the desired track on the disk 4.

[0018] FIG. 2 is a perspective view of the suspension 10 of FIG. 1 according to one embodiment of the present disclosure. 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, which constitutes a read / write head, is attached to the gimbal 21. In some embodiments, the slider includes a magnetoresistive (MR) element capable of converting between magnetic and electrical signals. The MR element serves to access data, i.e., write data to or read data from a disk (shown in FIG. 1).

[0019] The gimbal 21 includes microactuator elements 31 and 32. According to some embodiments, the microactuator elements 31 and 32 are formed of piezoelectric plates such as lead zirconate titanate (PZT). The microactuator elements 31 and 32 have a function of pivoting the slider in the rocking direction depending on their structure. It should be understood that any configuration of the microactuator elements may be implemented herein.

[0020] The suspension 10 includes a metal base 40. In some embodiments, the metal base 40 is formed of a stainless steel plate. The suspension 10 also includes a conductive circuit portion including one or more conductors, such as traces. The conductive circuit portion includes conductors that connect to the slider. The conductors may also connect to electrodes of the microactuator elements 31 and 32.

[0021] FIG. 3 illustrates a cross-sectional view of the microactuator element 31 of FIG. 2 according to one embodiment of the present disclosure. While piezoelectric elements are often used as microactuator motors, electrostatic microactuators and other types of microactuator motors may also be used. A commonly used piezoelectric material is lead zirconate titanate (PZT), although other piezoelectric materials may also be used. For simplicity, in this disclosure, piezoelectric devices that are microactuators may be referred to simply as "PZT" for short. It should be understood that the piezoelectric material need not be lead zirconate titanate. Thus, as used herein, the term "PZT" may refer to any piezoelectric material or any piezoelectric device formed from any piezoelectric material.

[0022] The microactuator element 31 may be multi-layered, with a first electrode 131A 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 electrically conductive adhesive (ECA) 34 at a fixed end. A cut portion 131B of the first electrode 131A may also be disposed on at least a portion of the bottom surface of the first PZT layer 131. The cut portion 131B may be connected to the first electrically conductive adhesive (ECA) 33 at a hinge end. A second electrode 132A may be disposed at least partially between the first PZT layer 131 and the second PZT layer 132. A third electrode 133A may be disposed at least partially between the second PZT layer 132 and the third PZT layer 133. Furthermore, a fourth electrode 134A may be disposed on at least a portion of the top surface of the third PZT layer 133. The cut 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.

[0023] The common length of first electrode 131A and second electrode 132A may define effective electrode length 131D. Additionally, the common length of third electrode 133A and fourth electrode 134A may define effective electrode length 133D. The fixed end refers to the leading end of head gimbal assembly 21 (shown in FIG. 2 ), and the hinge end refers to the trailing end of head gimbal assembly 21. In some embodiments, the length of fourth electrode 134A is 0.64 mm with a tolerance of 25 micrometers.

[0024] 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. The second side electrode 130B is connected to the second ECA 34.

[0025] In this configuration, the tolerance of the fourth electrode 134A significantly affects the torsional behavior of the gimbal at approximately 10.5 kHz of the PZT FRF. Shorter lengths of the fourth electrode 134A, specifically at approximately 0.335 mm Z-ht, result in significant variations in the PZT FRF. The large variations therefore impact the servo bandwidth of the disk drive 1 (shown in FIG. 1).

[0026] FIG. 4 illustrates a cross-sectional view of another microactuator element 71 according to one embodiment of the present disclosure. The fixed end refers to the leading edge of the gimbal 21 (shown in FIG. 2 ), and the hinge end refers to the trailing edge of the gimbal 21. In some embodiments, the overall length of the microactuator element 71 may be 0.80 mm with a tolerance of 25 μm. The microactuator element 71 may be a multi-layer PZT with a first electrode 331A disposed on at least a portion of the bottom surface of the first PZT layer 331. The first electrode 331A may be connected to a first electrically conductive adhesive (ECA) 33 at the hinge end. A cut portion 331B of the first electrode 331A may also be disposed on at least a portion of the bottom surface of the first PZT layer 331. The cut portion 331B may be connected to a second electrically conductive adhesive (ECA) 34 at the fixed end. A second electrode 332A may be disposed at least partially between the first PZT layer 331 and the second PZT layer 332.

[0027] The third electrode 333A may be disposed at least partially between the second PZT layer 332 and the third PZT layer 333. Furthermore, the fourth electrode 334A may be disposed on at least a portion of the upper surface of the third PZT layer 333. The cut portion 334B of the fourth electrode 334A may be disposed on at least a portion of the upper surface of the third PZT layer 333. The cut 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 cut 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. The second side electrode 330B is connected to the second ECA 34.

[0028] The common length of the first electrode 331A and the second electrode 332A may define an effective electrode length 331D. Furthermore, the common length of the third electrode 333A and the fourth electrode 334A may define an effective electrode length 333D. In the microactuator element 71, the fourth electrode 334A is positioned to directly connect to the second side electrode 330B at the fixed end. The fourth electrode 334A is also shortened relative to the fourth electrode 134A in FIG. 3 to maintain a near-zero phase angle at the nominal distance from the baseplate flange to the data disk surface, also referred to as the "z-height" or Z-ht. 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. The third electrode 333A may be 0.75 mm with a tolerance of 25 μm.

[0029] By connecting electrode 334A to second side electrode 330B at a fixed end, several advantages are realized. In some embodiments, the variation at low Z-ht is reduced from about 60° to about 40°. Another advantage is that the partial constraining layer construction (CLC) configuration increases stroke from 11 nm / V to 13.6 nm / V, according to some embodiments.

[0030] FIG. 5 shows a cross-sectional view of a microactuator element 81 according to one embodiment of the present disclosure. The microactuator element 81 may be multi-layered with a first electrode 431A disposed on at least a portion of a bottom surface of a first PZT layer 431. The first electrode 431A may be connected to a second electrically conductive adhesive (ECA) 134 at a fixed end. A cut 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 cut portion 431B may be connected to the first electrically conductive adhesive (ECA) 133 at a hinge end. A second electrode 432A may be disposed at least partially between the first PZT layer 431 and the second PZT layer 432. A third electrode 433A may be disposed on at least a portion of a top surface of the second PZT layer 432. A cut portion 433B of the third electrode 433A may be disposed on at least a portion of a top surface of the second PZT layer 432.

[0031] The common length of the first electrode 431A and the second electrode 432A may define an effective electrode length 431D. Furthermore, the common length of the third electrode 433A and the second electrode 432A may define an effective electrode length 433D. The fixed end refers to the leading end of a head gimbal assembly, such as the head gimbal assembly shown in FIG. 2. The hinged end refers to the trailing end of the head gimbal assembly.

[0032] The third electrode 433A and the first electrode 431A are connected to a first side electrode 430A at the hinge end of the microactuator element 81. The third electrode 433B, the second electrode 432A, and the cut portion 431B are connected to a 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. The second side electrode 430B is connected to the second ECA 134.

[0033] FIG. 6 illustrates a cross-sectional view of another microactuator element 91 according to one embodiment of the present disclosure. The fixed end refers to the leading end of a gimbal, such as the gimbal 21 shown in FIG. 2 . The hinged end refers to the trailing end of the gimbal. In some embodiments, the overall length of the microactuator element 91 may be 0.80 mm with a tolerance of 25 μm. The microactuator element 91 may be a multi-layer PZT with a first electrode 531A 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 the fixed end. A cut 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 cut portion 531B may be connected to a second conductive adhesive (ECA) 233 at the hinged end. The second electrode 532A may be disposed at least partially between the first PZT layer 531 and the second PZT layer 532.

[0034] The third electrode 533A may be disposed on at least a portion of the top surface of the second PZT layer 532. The cut portion 533B of the third electrode 534A may be disposed on at least a portion of the top surface of the second PZT layer 532. The cut portion 533B may be connected to the first ECA 233 at the hinge end 233 via the first side electrode 530A. In some embodiments, the cut 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 the 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 cut portion 531B. The second side electrode 530B is connected to the second ECA 234.

[0035] The common length of the first electrode 531A and the second electrode 532A may define an effective electrode length 531D. Furthermore, the common length of the third electrode 533A and the second electrode 532A may define an effective electrode length 533D. In the microactuator element 91, the third electrode 533A is positioned to connect directly to the second side electrode 530B at its fixed end. In some embodiments, the length of the third electrode 533A is shortened to maintain a near-zero phase angle at a nominal distance from the baseplate flange to the data disk surface, also referred to as the "z-height" or Z-ht. In some cases, the near-zero phase angle is 2 degrees.

[0036] By connecting the third electrode 534A to the second side electrode 530B at a fixed end, several advantages are realized. In some embodiments, the variation at low Z-ht is reduced from about 60° to about 40°. Another advantage is that the partial constrained layer construction (CLC) configuration increases the stroke from 11 nm / V to 13.6 nm / V, according to some embodiments.

[0037] The present disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other modifications without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

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

2. 2. The PZT actuator assembly of claim 1, wherein the cut portion connected to the first side electrode at the hinge end is 0.05 mm.

3. 10. The PZT actuator assembly of claim 1, wherein said fourth electrode is 0.25 mm with a tolerance of 25 μm.

4. 10. The PZT actuator assembly of claim 1, wherein said second electrode is 0.70 mm with a tolerance of 25 μm.

5. 10. The PZT actuator assembly of claim 1, wherein said third electrode is 0.75 mm with a tolerance of 25 μm.

6. A suspension, the suspension comprising: a flexure attached to the load beam, the flexure including one or more electrical traces; and one or more multi-layer piezoelectric (PZT) microactuator assemblies coupled to at least one of the one or more electrical traces and having a fixed end and a hinged end, each of the multi-layer piezoelectric (PZT) microactuator assemblies comprising: a first side electrode at the hinge end; a second side electrode of the fixed end; a first PZT layer including a top surface and a bottom surface; a first electrode disposed at least partially on the bottom surface of the first PZT layer; a second PZT layer disposed on the top surface of the first PZT layer, the second PZT layer including a top surface and a bottom surface; 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 connected to the second side electrode at the fixed end; a third PZT layer disposed on the top surface of the second PZT layer and including a top surface and a bottom surface; a third electrode disposed at least partially on the bottom surface of the third PZT layer and at least partially on the top surface of the second PZT layer, the third electrode connected to the first side electrode at the hinge end; a fourth electrode at least partially disposed on the top surface of the third PZT layer, the fourth electrode being connected to the second side electrode at the fixed end; the cut portion of the first electrode is separated from the first electrode, disposed along a portion of the bottom surface of the first PZT layer, and configured to be electrically connected to the conductive adhesive at the fixed end via the second side electrode; the cut portion of the fourth electrode is separated from the fourth electrode, disposed along a portion of the top surface of the third PZT layer, and configured to be electrically connected to a conductive adhesive at the hinge end via the first side electrode; A suspension in which the length of the cut portion of the fourth electrode is shorter than the length of the cut portion of the first electrode.

7. The suspension of claim 6 , wherein the cut portion connected to the first side electrode at the hinge end is 0.05 mm.

8. The suspension of claim 6 , wherein the fourth electrode is 0.25 mm with a tolerance of 25 μm.

9. The suspension of claim 6 , wherein the second electrode is 0.70 mm with a tolerance of 25 μm.

10. The suspension of claim 6 , wherein the third electrode is 0.75 mm with a tolerance of 25 μm.

11. An actuator assembly having a fixed end and a hinged end, said assembly comprising: a first side electrode; a second side electrode; a first PZT layer including a top surface and a bottom surface; a first electrode disposed at least partially on the bottom surface of the first PZT layer; a second PZT layer disposed on the top surface of the first PZT layer, the second PZT layer including a top surface and a bottom surface; a second electrode disposed at least partially on the bottom surface of the second PZT layer and at least partially on the top surface of the first PZT layer, the second electrode connected to the second side electrode; a third electrode disposed at least partially on the top surface of the second PZT layer, the third electrode connected to the first side electrode; the cut portion of the first electrode is separated from the first electrode, disposed along a portion of the bottom surface of the first PZT layer, and configured to be electrically connected to a conductive adhesive at the hinge end via the first side electrode; the cut portion of the third electrode is separated from the third electrode, disposed along a portion of the top surface of the second PZT layer, and configured to be electrically connected to a conductive adhesive at the hinge end via the first side electrode; An actuator assembly, wherein the length of the cut portion of the third electrode is shorter than the length of the cut portion of the first electrode.

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

13. 12. The PZT actuator assembly of claim 11, wherein the second electrode is 0.70 mm with a tolerance of 25 μm.

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