Three-stage design for actuator mounting process on flexure

Abstract

A method for manufacturing a three-stage assembly is provided. The method includes attaching a first microactuator and a second microactuator to a trace gimbal on a flexure during a PZT-on-Flexure process (POF). The first microactuator is located at a distal end of the flexure, and the second microactuator is located at a proximal end of the flexure. The method also includes welding the trace gimbal to a base plate and a load beam to secure the trace gimbal, including the first microactuator and the second microactuator.

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention generally relate to an improved process for mounting an actuator to a suspension. [Background technology]

[0002] A hard disk drive (HDD) is a non-volatile storage device that stores digitally encoded data on one or more circular disks (sometimes called platters) with magnetic surfaces housed in a protective enclosure. During operation of an HDD, each magnetic-recording disk is rotated at high speed by a spindle system. Data is read from and written to the magnetic-recording disks using read / write heads that are positioned over specific locations on the disks by an actuator.

[0003] A read / write head uses a magnetic field to read data from and write data to the surface of a magnetic-recording disk. Because a magnetic dipole field decreases rapidly with distance from the magnetic pole, the distance between the read / write head, housed in a slider, and the surface of the magnetic-recording disk must be tightly controlled. The actuator partially relies on the force of a suspension on the slider and the aerodynamic properties of the slider air bearing surface (ABS) to provide the proper distance ("flying height") between the read / write head and the surface of the magnetic-recording disk while the magnetic-recording disk rotates.

[0004] Increases in areal density (a measure of the amount of information bits that can be stored on a given area of ​​the disk surface) have led to the necessary development and implementation of secondary and tertiary actuators for improved head positioning through relatively fine positioning, in addition to primary voice coil motor (VCM) actuators, which provide relatively coarse positioning. Some hard disk drives employ microactuator or milliactuator designs to provide second- and / or third-stage actuation of the recording head, enabling more precise positioning of the head relative to the recording track. Milliactuators are broadly classified as actuators that move the entire leading end of the suspension, i.e., the spring, load beam, flexure, and slider, and are typically used as second-stage actuators. Microactuators are typically used as third-stage actuators and are broadly classified as actuators that move only the slider, actuators that move the slider relative to the suspension and load beam, or actuators that move only the read / write element relative to the slider body. Third-stage actuators are used in conjunction with first-stage actuators (e.g., VCMs) and second-stage actuators (e.g., milliactuators) for more precise head positioning. Summary of the Invention [Problem to be solved by the invention]

[0005] There is a continuing need for improved suspensions. Suspensions with improved performance are desired. Suspensions should be capable of being efficiently manufactured. [Means for solving the problem]

[0006] A method for fabricating a tri-stage assembly is provided. The method includes attaching a first actuator (e.g., mPZT) and a second actuator (e.g., uPZT) to a trace gimbal during a PZT-on-flexure (POF) process. The mPZT is located at the proximal end of the uPZT. The method also includes welding the base plate, load beam, and trace gimbal together, followed by subsequent suspension fabrication processes, including, but not limited to, attachment of damper materials and other process techniques.

[0007] In some implementations, the base plate is constructed of stainless steel. Furthermore, the mPZT and uPZT microactuators may be operable in transverse, shear, or bending modes. The uPZT may be located in the gimbal head of the tracing gimbal. Furthermore, the mPZT may be located opposite the gimbal head of the tracing gimbal in the load beam region.

[0008] The method may also include welding a shelf with a folding feature to the trace gimbal before attaching the mPZT and uPZT to the trace gimbal, hi some implementations, the folding feature is positioned at 80 degrees relative to the load beam.

[0009] A three-stage assembly is also provided. The three-stage assembly includes a microactuator having a proximal end and a distal end. The three-stage assembly may also include a first electrode attached to a top surface of the microactuator and a second electrode attached to a bottom surface of the microactuator. The three-stage assembly may also include a first conductive adhesive contacting at least a portion of the first electrode at the proximal end to connect the first electrode to the tracing gimbal, and a second conductive adhesive contacting at least a portion of the second electrode to connect the second electrode to the tracing gimbal.

[0010] The three-stage assembly may also include a first non-conductive adhesive in contact with the second electrode and at least a portion of the microactuator at the proximal end to secure the microactuator to the trace gimbal. A second non-conductive adhesive may also be included in contact with at least a portion of the second electrode at the distal end. The three-stage assembly may also include a shelf feature on the trace gimbal configured to connect to the second non-conductive adhesive.

[0011] In some implementations, a second conductive adhesive is located at the distal end to connect the second electrode to the trace gimbal. In other implementations, a second conductive adhesive may be located between the proximal end and the distal end to connect the second electrode to the trace gimbal.

[0012] Other features and advantages of implementations of the present invention will be apparent from the accompanying drawings and from the detailed description that follows. Implementations of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference symbols indicate similar elements and in which: [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of a suspension having a flexure with a three-stage actuation structure according to one implementation. [Figure 2] FIG. 2 is a perspective view of the underside of the three-stage actuation structure of FIG. 1. [Figure 3] 1 is a flowchart illustrating a process for manufacturing a three-stage actuation structure according to one implementation. [Figure 4] FIG. 1 illustrates an exemplary first trace gimbal design, according to one implementation. [Figure 5] 5 is a cross-sectional view of a first microactuator attached to the trace gimbal of FIG. 4 according to one implementation. [Figure 6] 5 is a flowchart illustrating a process for manufacturing a three-stage actuation structure with the trace gimbal design of FIG. 4 according to one implementation. [Figure 7]FIG. 1 illustrates an exemplary second trace gimbal design, according to one implementation. [Figure 8] FIG. 8 is a cross-sectional view of a first microactuator attached to the second trace gimbal design of FIG. 7 according to one implementation. [Figure 9] 8 is a flowchart illustrating a process for manufacturing a three-stage actuation structure with the second trace gimbal design of FIG. 7 according to one implementation. DETAILED DESCRIPTION OF THE INVENTION

[0014] A preferred implementation of the disclosed suspension structure and manufacturing process allows for direct attachment between the first microactuator and the trace gimbal. After attachment, the trace gimbal is welded to a mount plate to secure the first microactuator. As a result, this process does not require the injection of unnecessary adhesive to secure the first microactuator to the base plate. Adhesives pose potential contamination issues within the disk drive suspension clean room assembly environment. Consequently, minimizing the use of adhesives helps reduce manufacturing complexity and cost and increase the reliability of the disk drive assembly.

[0015] FIG. 1 is a perspective view of a suspension 2 having a co-located or gimbal-based actuation structure 16. FIG. 2 is a perspective view of the underside of the suspension 2. The suspension 2 may include a flexure 4 and a base plate 6. The base plate 6 may be configured as a proximal mounting structure. The suspension 2 may also include a load beam 8 having a rigid or beam region 10. The beam region 10 may be connected to the base plate 6 along a spring or hinge region 12. The load beam 8 may be formed from stainless steel.

[0016] The flexure 4 may include a trace gimbal 14 at the distal end of the flexure 4. The actuation structure 16 may be located on the trace gimbal 14 adjacent to the distal end of the load beam 8. For purposes of explanation, the terms proximal and distal refer to relative directions along the longitudinal axis of the suspension 2. For example, the base plate 6 is at the proximal end of the load beam 8. Axial keys 13 indicate the X, Y, and Z axes in Figures 1 and 2. The suspension 2 is generally elongated along the X axis in the proximal and distal directions. The Y axis represents the lateral direction from side to side. The suspension 2, including the flexure 4, is generally coplanar with the XY plane defined by the X and Y axes. The Z axis represents height and bottom-to-top orientation.

[0017] The suspension 2 may also include a first microactuator 17 (e.g., an mPZT). The first microactuator 17 may be mounted on the base plate 6 and configured to move the load beam 8. Extension and contraction of the first microactuator 17 causes the load beam 8 of the suspension 2 to move, more specifically, rotate the entire load beam 8. The base plate 6 may include a pseudo-feature 19 and may be configured to receive and secure the first microactuator 17. Specifically, the pseudo-feature 19 balances the mass, mass distribution, and stiffness of the first microactuator 17. The pseudo-feature 19 may be fabricated separately and then secured to the base plate 6 by laser welding, adhesive, or the like. The pseudo-feature 19 may also be fabricated integrally with the base plate 6, partially or entirely. Because the base plate 6 is typically made of stainless steel (SST), the pseudo-feature may be integrally formed with the base plate 6 from a single piece of stainless steel. Etching or laser ablation can create regions of greater and lesser thickness and width within pseudo-feature 19. Additionally, laser processing can locally change the mechanical properties of the stainless steel within pseudo-feature 19, for example, creating locally softer regions, which can be useful for fine-tuning the properties of pseudo-feature 19.

[0018] The first microactuator 17 is fixed to the base plate 6 using a non-conductive adhesive. For example, a non-conductive adhesive such as an epoxy adhesive may be applied to attach the first microactuator 17, or a conductive adhesive may be applied to electrically bridge a copper pad to the top surface of the first microactuator 17, which defines the drive voltage electrode for the microactuator. A second microactuator or pair of microactuators, such as a constrained layer construction (CLC) PZT microactuator, may be attached to the trace gimbal 14 in the receiving space 18. The pair of microactuators on either side of the trace gimbal 14 act in a push-pull manner on the gimbal to rotate the head slider. The head slider includes a magnetic read transducer and a magnetic write transducer, respectively, to read and write data from and to the disk drive platter. Because the first microactuator 17 is attached between the base plate 6 and the load beam 8, it may be configured for coarse movement (m-step). A second microactuator is mounted on the flexure 4 and may be configured to provide fine adjustment (u stage).

[0019] FIG. 3 shows an exemplary flowchart illustrating a process 200 for manufacturing the suspension 2 of FIGS. 1 and 2. The process 200 will be described in detail with reference to the components of the suspension 2 of FIGS. 1 and 2. First, in step 201, the second microactuator is attached to the trace gimbal 14 in the receiving space 18. Specifically, an area of ​​adhesive, such as an epoxy adhesive, may be applied to the receiving space 18, and a conductive adhesive may be applied to electrically bridge a copper pad to the top surface of the second microactuator and define a drive voltage electrode for the second microactuator. In step 202, the base plate 6, the load beam 8, and the trace gimbal 14 are welded together. In step 203, a damping material is attached to the suspension 2. For example, the damping material may be a viscoelastic damping layer inserted between the second microactuator and the suspension to provide passive damping. The speed of the spindle motor in modern high-performance hard disk drives is constantly increasing to meet this demand. However, high-speed rotation generates airflow within the drive, which significantly affects head positioning accuracy. The viscoelastic layer attached to the suspension suppresses structural resonance modes of the suspension excited by airflow and reduces the transmission of vibrations excited by external shocks from the carriage arm to the suspension. Furthermore, both the active control provided by the controlled microactuator elements and VCM and the passive damping from the viscoelastic layer can contribute to precise positioning and vibration suppression during track seeking and following.

[0020] Next, in step 204, the first microactuator 17 is attached to the base plate 6. Similar to step 201, an area of ​​adhesive, such as epoxy adhesive, is applied to the receiving space for the first microactuator 17, and a conductive adhesive is applied to electrically bridge the copper pads to the top surface of the first microactuator and define the drive voltage electrodes for that microactuator. As shown herein, the attachment of the first and second microactuators is performed in two separate process steps. As a result, the manufacturing process requires extra manufacturing costs and the injection of additional adhesive after the welding process (step 202). Implementations disclosed herein provide a trace gimbal design that allows the first microactuator 17 to be attached to the flexure 4.

[0021] FIG. 4 illustrates an exemplary first trace gimbal 400 according to one implementation. This illustration is merely an example and should not unduly limit the scope of the claims. Those skilled in the art will recognize many other variations, modifications, and alternatives. As shown, the trace gimbal 400 includes a head portion 403. By way of example only, a pair of PZT elements 402 are attached to the head portion 403 of the gimbal 400. The PZT elements 402 may be mounted on a co-located uDSA flexure design using techniques including those known in the art. The first and second microactuators or microactuator pair (uPZT) can operate in transverse, shear, or bending modes. During slider rotation, one of the PZT actuators increases in length and the other decreases in length, thereby generating rotational motion. Of course, many other variations, alternatives, and modifications are possible.

[0022] The third microactuator (mPZT) 405 may also be attached directly to the trace gimbal 400. Once the first, second, and third microactuators are attached to the trace gimbal 400, the trace gimbal 400 can be welded to a base plate. As described in more detail below, the attachment of the microactuator pair (uPZT) and the third microactuator (mPZT) is performed in one step. With particular reference to FIG. 4 , the overall width W of the trace gimbal 400 is between 1.5 mm and 3 mm. In some examples, the overall width W of the trace gimbal 400 is 2.040 mm. In some implementations, two or more mPZTs may be provided with a narrow profile to avoid impacting panel density. The attachment of the additional mPZTs is performed in the same step as the attachment of the microactuator pair (uPZT) and the third microactuator (mPZT). The configuration of the base plate may be modified to account for the trace gimbal 400.

[0023] FIG. 5 shows a cross-sectional view of a microactuator 417 (e.g., an mPZT) attached to a trace gimbal 400 according to one implementation. The microactuator 417 may include a proximal end and a distal end. A first electrode 418 may be attached to the top surface of the microactuator 417. Additionally, a second electrode may be attached to the bottom surface of the microactuator 417. A first conductive adhesive 416A may be attached to at least a portion of the first electrode 418A at the proximal end. The first conductive adhesive 416A can connect the first electrode 418A to the trace gimbal 400. The second conductive adhesive 416B is configured to contact at least a portion of the second electrode 418B. The second conductive adhesive 416B can connect the second electrode 418B to the trace gimbal 400. Specific to this configuration, the second conductive adhesive 416B is located at the distal end to connect the second electrode 418B to the trace gimbal 400. Various other implementations are described below with respect to FIG.

[0024] The first non-conductive adhesive 415 may be configured to contact the second electrode 418B at the proximal end and at least a portion of the microactuator 417. The first non-conductive adhesive 415 serves to secure the microactuator 417 in place relative to the trace gimbal 400. The conductive adhesive 416B may connect the trace elements, i.e., copper 414, and an insulating layer 413, such as a polyimide layer.

[0025] In some implementations, the trace gimbal 400 may include a folding feature 401 to enable electrical connection between the first electrode 418A, the microactuator 417, and the first conductive adhesive 416A. The folding feature 401 may vary its position relative to the trace gimbal 400. In some implementations, the folding feature 401 may be at an angle of 60 to 85 degrees (e.g., 80 degrees) relative to the trace gimbal 400. In alternative implementations, the microactuator 417 may be configured such that both the first and second electrodes 418 are accessible, eliminating the need for the folding feature 401.

[0026] FIG. 6 is a flowchart illustrating a process 600 for manufacturing a suspension having a trace gimbal 400 design. The process 600 will be described in detail with reference to the components of the suspension including the trace gimbal 400 of FIG. 4. First, in step 601, the trace gimbal 400 is provided with an attached first microactuator (mPZT) and a second microactuator (uPZT). In step 602, the base plate 406 and the load beam 408 are welded together. In step 603, a damping material may be attached. The damping material may include, for example, a viscoelastic damping layer. The viscoelastic damping layer is inserted between the first microactuator (mPZT) and the second microactuator (uPZT) and the suspension to provide passive damping. The viscoelastic layer attached to the suspension suppresses structural resonance modes of the suspension excited by airflow and reduces the transmission of vibrations excited by external shocks from the carriage arm to the suspension. Other processes may follow step 603, including, but not limited to, pre-gram formation and other suspension processes.

[0027] As shown herein, after attachment, the trace gimbal is welded to the mounting plate to secure the first microactuator. As a result, the attachment of the first and second microactuators is performed in a single process step. Furthermore, this process does not require the injection of unnecessary adhesive to secure the first microactuator to the base plate. Because adhesives pose potential contamination issues within the disk drive suspension clean room assembly environment, minimizing the use of adhesives helps reduce manufacturing complexity and costs and increase the reliability of the disk drive assembly. Therefore, this manufacturing process reduces manufacturing steps and associated costs.

[0028] 7 shows an exemplary design of a second trace gimbal 700 according to one implementation. The first and second microactuators may be directly attached to the trace gimbal 700. As described above, the attachment of the first microactuator (mPZT) and the second microactuator (uPZT) is performed in one step. Compared to the trace gimbal 400, the trace gimbal 700 includes a shelf feature 702.

[0029] FIG. 8 shows a cross-sectional view of a first microactuator 717 attached to a trace gimbal 700, according to one implementation. As described above, the first microactuator 717 may include a proximal end and a distal end. A notable difference between the first microactuator 417 of FIG. 5 and the first microactuator 717 of FIG. 8 is the addition of a shelf feature 702 on the trace gimbal 700. Additionally, a second conductive adhesive 716B is disposed between the proximal end and the distal end to connect a second electrode 718B to the trace gimbal 700.

[0030] The first non-conductive adhesive 715A may be configured to contact the second electrode 718B at the proximal end and at least a portion of the first microactuator 717. The first non-conductive adhesive 715A serves to secure the first microactuator 717 in place relative to the trace gimbal 700. The second conductive adhesive 716B may connect the trace elements, i.e., copper 714, and an insulating layer 713, such as a polyimide layer.

[0031] The second non-conductive adhesive 715B may be configured to contact at least a portion of the second electrode 718B at the tip. The shelf feature 702 of the trace gimbal 700 may be configured to connect to and support the second non-conductive adhesive 718B.

[0032] The shelf feature 702 and the fold feature 701 cooperate to enable electrical connection between the first electrode 718A and the second electrode 718B of the first microactuator 717. As detailed above, the fold feature 701 can vary its position relative to the trace gimbal 700.

[0033] FIG. 9 is a flowchart illustrating a process 900 for manufacturing a suspension including a trace gimbal 700. The process 900 will be described in detail with reference to the components of the suspension including the trace gimbal 700 of FIG. 7. As a first matter, in step 901, the trace gimbal 700 is provided with a shelf feature 702 by welding. In step 902, first and second microactuators are attached. In step 903, the base plate 706, the load beam 708, and the trace gimbal 700 are welded together. In step 904, a damping material is attached to the suspension. As described above, the damping material may include, for example, a viscoelastic damping layer. The viscoelastic damping layer is attached to the suspension for passive damping. The viscoelastic layer attached to the suspension suppresses structural resonance modes of the suspension excited by airflow and reduces the transmission of vibrations excited by external shocks from the carriage arm to the suspension.

[0034] As described herein, the attachment of the first and second microactuators is performed in a single process step. As a result, the manufacturing process reduces manufacturing steps and associated costs. Furthermore, the manufacturing process does not include an additional adhesive injection after the welding step, as is commonly done. Also, the suspension according to the implementations described herein has a reduced sway frequency compared to current suspensions. Therefore, the suspension described herein has improved operating performance.

[0035] According to some implementations, the processes described herein are used to form one or more of any of mechanical and electromechanical structures. While described with reference to these implementations, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention. The technical ideas that can be understood from the above embodiment will be described below. [Appendix 1] 1. A method of manufacturing a three-stage assembly, comprising: attaching a first microactuator and a second microactuator to a trace gimbal on a flexure during a PZT-on-Flexure process (POF), the first microactuator being located at a distal end of the flexure and the second microactuator being located at a proximal end of the flexure; welding the trace gimbal to a base plate and a load beam to secure the trace gimbal, including the first micro-actuator and the second micro-actuator. [Appendix 2] 2. The method of claim 1, wherein the base plate is made of stainless steel. [Appendix 3] 2. The method of claim 1, wherein the first microactuator and the second microactuator are attached to the flexure in a transverse mode, a shear mode, or a bending mode. [Appendix 4] 2. The method of claim 1, wherein the second microactuator is located on a gimbal head of the tracing gimbal. [Appendix 5] 5. The method of claim 4, wherein the first microactuator is located on an opposite side of the trace gimbal from the gimbal head in a load beam region. [Appendix 6] 10. The method of claim 1, further comprising welding a shelf having a folding feature to the tracing gimbal before attaching the first microactuator and the second microactuator to the tracing gimbal. [Appendix 7] 7. The method of claim 6, wherein the folding feature is positioned at an angle of 60 to 85 degrees relative to the load beam. [Appendix 8] 8. The method of claim 7, wherein the folding feature is positioned at 80 degrees relative to the load beam. [Appendix 9] 10. The method of claim 1, further comprising attaching a damping material to provide passive damping. [Appendix 10] A three-stage assembly formed on a flexure, a first microactuator located at a distal end of the flexure, the first microactuator including a proximal end and a distal end; a first electrode attached to a top surface of the first microactuator and a second electrode attached to a bottom surface of the first microactuator; a first conductive adhesive configured to contact at least a portion of the first electrode at the proximal end to connect the first electrode to a trace gimbal; a second conductive adhesive configured to contact at least a portion of the second electrode to connect the second electrode to the trace gimbal. [Appendix 11] 11. The three-stage assembly of claim 10, further comprising a first non-conductive adhesive configured to contact the second electrode and at least a portion of the first microactuator at the base end to secure the first microactuator to a mounting plate. [Appendix 12] 11. The three-stage assembly of claim 10, further comprising a second non-conductive adhesive configured to contact at least a portion of the second electrode at the tip. [Appendix 13] 13. The three-stage assembly of claim 12, further comprising a shelf feature on the trace gimbal configured to connect to a second non-conductive adhesive. [Appendix 14] 14. The three-stage assembly of claim 13, wherein the second conductive adhesive is located at the tip to connect the second electrode to the trace gimbal. [Appendix 15] 14. The three-stage assembly of claim 13, wherein the second conductive adhesive is positioned between the proximal end and the distal end to connect the second electrode to the trace gimbal. [Appendix 16] 11. The three-stage assembly of claim 10, further comprising a second microactuator located at a proximal end of the flexure opposite the first microactuator. [Appendix 17] 17. The three-stage assembly of claim 16, wherein the second microactuator is located on a gimbal head of the flexure. [Appendix 18] 18. The three-stage assembly of claim 17, wherein the first microactuator is located on an opposite side of the flexure from the gimbal head in a load beam region. [Appendix 19] 11. The three-stage assembly of claim 10, wherein the trace gimbal comprises a folding feature to enable electrical connection between the first electrode, the first microactuator, and the first conductive adhesive.

Claims

1. 1. A method of manufacturing a three-stage assembly, comprising: attaching a first microactuator and a second microactuator to a trace gimbal on a flexure during a PZT-on-Flexure process (POF), the first microactuator being located at a distal end of the flexure and the second microactuator being located at a proximal end of the flexure; welding the trace gimbal, including the first micro-actuator and the second micro-actuator, to a base plate and a load beam to secure the trace gimbal.

2. The method of claim 1 , wherein the base plate is constructed from stainless steel.

3. The method of claim 1 , wherein the first microactuator and the second microactuator are attached to the flexure in a transverse mode, a shear mode, or a bending mode.

4. The method of claim 1 , further comprising welding a shelf with a folding feature to the tracing gimbal before attaching the first microactuator and the second microactuator to the tracing gimbal.

5. The method of claim 4 , wherein the fold feature is positioned at an angle between 60 degrees and 85 degrees relative to the load beam.

6. The method of claim 5 , wherein the fold feature is positioned at 80 degrees relative to the load beam.

7. The method of claim 1 further comprising attaching a damping material to provide passive damping.

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