Actuator joint with non-straight edges

Abstract

To provide a suspension capable of increasing impact resistance without losing stroke characteristics.SOLUTION: A suspension is described. The suspension includes a base plate and a load beam coupling to the base plate. The base plate includes a distal elongated element and a proximal elongated element. The distal elongated element includes one or more non-straight base plate edges and the proximal elongated element includes one or more non-straight base plate edges. The load beam includes a first mounting shelf and a second mounting shelf. The load beam is coupled to the base plate such that the first mounting shelf is exposed adjacent to the distal elongated element and the second mounting shelf is exposed adjacent to the proximal elongated element. The first mounting shelf and the second mounting shelf are configured to receive an actuator such that an edge of the actuator and one or more non-straight base plate edges form a gap.SELECTED DRAWING: Figure 5A

Description

[Technical field]

[0001] The present disclosure relates to the field of suspensions for hard disk drives, and more particularly, to actuator joints on actuated suspensions configured to improve stiffness. [Background technology]

[0002] Dynamic hard disk storage devices use rotating disks to store information. Hard disk storage devices typically include a frame that provides mounting points and orientation for other components, and a spindle motor attached to the frame to rotate the disk. A read / write head is located on a "head slider" for writing data to and reading data from the disk surface. The head slider is supported and properly oriented relative to the disk by a head suspension that provides both the force and resilience required for proper head slider operation. As the disk in the storage device rotates under the head slider and head suspension, the air above the disk also rotates, creating an air bearing. The air bearing works with the aerodynamic design of the head slider to generate a lift force on the head slider. The lift force is opposed by the spring force of the head suspension to position the head slider at a desired height and alignment above the disk, called the "flying height."

[0003] A head suspension for a hard disk drive includes a load beam and a flexure. The load beam typically includes a mounting region for mounting the head suspension to an actuator of the disk drive, a rigid region, and a spring region between the mounting region and the rigid region. The spring region provides a spring force to counteract the aerodynamic lift force generated on the head slider during the drive operation described above. The flexure typically includes a gimbal region having a slider mounting surface to which the head slider is attached. The gimbal region is elastically movable relative to the rest of the flexure in response to the aerodynamic force generated by the air bearing. The gimbal region can move the head slider in pitch and roll directions to follow variations in the disk surface.

[0004] In some instances, the flexure is formed as a separate piece with a load beam attachment region that is rigidly attached to the distal end of the load beam using conventional methods such as spot welding. This type of head suspension typically includes a load point dimple formed in either the load beam or gimbal region of the flexure. The load point dimple transfers a portion of the load generated by the spring region of the load beam, i.e., the gram load, to the flexure, provides clearance between the flexure and the load beam, and serves as a point at which the head slider is gimbaled in the pitch and roll directions to follow variations in the disk surface.

[0005] Disk drive manufacturers continue to develop smaller and higher storage capacity drives. The increased storage capacity is achieved in part by increasing the density of the information tracks on the disk (i.e., by using narrower and / or more closely spaced tracks). However, as track density increases, it becomes increasingly difficult for the motor and servo control systems to quickly and accurately position the read / write head over the desired track. In an attempt to remedy this situation, separate or secondary actuators have been provided, such as piezoelectric actuators, electrostatic actuators, electromagnetic actuators or fine tracking motors mounted on the head suspension itself. These types of actuators are also known as two-stage microactuation devices and may be located on the base plate, load beam, or flexure.

[0006] In some of these attempts to improve tracking and head slider positioning control, an actuator has been placed on the head slider itself. Typically, this type of actuator is sandwiched between the head slider and a head slider mounting surface of a flexure or other suspension component, or is directly coupled to the head slider. Movement of the actuator typically results in relatively direct movement of the head slider, thus providing the desired fine movement of the read / write head over the track of the disk drive. Summary of the Invention [Problem to be solved by the invention]

[0007] One issue with this type of configuration is the shock resistance, especially for piezoelectric configurations. In these configurations, much of the shock load passes through the piezoelectric element, so the amount of shock that can be withstood is limited by the fracture limit of the piezoelectric material. Making the piezoelectric element thicker, wider, or shorter increases the shock resistance by increasing the stiffness of the element, but this change also reduces the amount of stroke provided by the element. It would be advantageous to increase the shock resistance without losing stroke characteristics. [Means for solving the problem]

[0008] A suspension is described. The suspension includes a base plate and a load beam coupled to the base plate. The base plate includes a distal elongate element and a proximal elongate element. The distal elongate element includes one or more non-linear base plate edges and the proximal elongate element includes one or more non-linear base plate edges. The load beam includes a first mounting shelf and a second mounting shelf. The load beam is coupled to the base plate such that the first mounting shelf is exposed adjacent the distal elongate element and the second mounting shelf is exposed adjacent the proximal elongate element. The first mounting shelf and the second mounting shelf are configured to receive an actuator such that an edge of the actuator and the one or more non-linear base plate edges form a gap.

[0009] In some embodiments of the suspension, the gap is filled with a first adhesive, the first adhesive being a non-conductive adhesive or a conductive adhesive. The non-linear baseplate edges improve the tolerances associated with placement of the actuator and application of the first adhesive. Any of the non-linear baseplate edges may include one or more linear baseplate edges and one or more recesses.

[0010] A base plate arrangement is also provided. The base plate arrangement includes a distal elongate element including one or more non-linear base plate edges. The base plate arrangement also includes a proximal elongate element spaced from the distal elongate element by an actuator receiving space. In some embodiments, the proximal elongate element includes one or more non-linear base plate edges.

[0011] In some embodiments of the base plate arrangement, the non-linear base plate edges may be configured to compensate for actuator placement characteristics and first adhesive application characteristics, any of which may include one or more linear base plate edges and one or more recessed portions.

[0012] A suspension device is also provided. The suspension device includes a gimbal assembly. The gimbal assembly includes an actuator attached to the suspension device at a fixed end and a hinged end opposite the fixed end. The gimbal assembly also includes a first electrode on a top surface of the actuator. A second electrode is disposed on a bottom surface of the actuator. The second electrode is coupled to a conductive layer on the suspension device by a conductive adhesive. The gimbal assembly also includes a metal base layer disposed at the hinged end. The metal base layer includes a non-linear metal layer edge configured to form a gap between an edge of the actuator and the metal base layer. The gap is configured to receive a non-conductive adhesive that prevents and / or reduces the likelihood of an electrical short between the conductive adhesive and the metal base layer.

[0013] In some embodiments of the suspension, the non-linear edge of the metallic base layer includes one or more linear edges and one or more recesses. The conductive layer may be a copper layer. The metallic base layer includes a stainless steel layer.

[0014] A gimbal assembly is also provided. The gimbal assembly includes an actuator attached to the suspension device at a fixed end and a hinged end opposite the fixed end. The gimbal assembly also includes a first electrode on a top surface of the actuator. A second electrode is disposed on a bottom surface of the actuator. The second electrode is coupled to a conductive layer on the suspension device by a conductive adhesive. The gimbal assembly also includes a metal base layer disposed at the hinged end. The metal base layer includes a non-linear metal layer edge configured to form a gap between an edge of the actuator and the metal layer. The gap is configured to receive a non-conductive adhesive that reduces the possibility of an electrical short between the conductive adhesive and the metal base layer.

[0015] In some embodiments of the gimbal assembly, the non-linear edge of the metallic base layer includes one or more linear edges and one or more recessed portions. While multiple embodiments are disclosed, still other embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the present disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. [Brief description of the drawings]

[0016] [Figure 1] 1 is a top perspective view of a conventional magnetic disk drive unit; [Diagram 2] FIG. 2 is a top view of the suspension of the disk drive of FIG. 1; [Diagram 3] FIG. 2 illustrates an actuator joint of a suspension according to an example of the present disclosure. [Figure 4] 4 illustrates the actuator joint of FIG. 3 without the actuator according to an example of the present disclosure. [Figure 5A] FIG. 2 illustrates an actuator joint of a suspension according to an example of the present disclosure. [Figure 5B] FIG. 5B illustrates the actuator joint of FIG. 5A without the actuator according to an example of the present disclosure. [Figure 6]FIG. 2 illustrates a gimbal of a suspension according to an example of the present disclosure. [Figure 7] FIG. 7 is a cross-sectional view of the actuator region taken along line BB' in FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] FIG. 1 is a top perspective view of a magnetic disk drive unit 100. The disk drive unit 100 includes a rotating magnetic disk 101 having a pattern of magnetic ones and zeros that constitute the data stored on the disk drive. The magnetic disk 101 is driven by a drive motor. The disk drive unit 100 further includes a suspension 105 to which a magnetic head slider is attached near a distal end of a load beam 107. The "proximal" end of the suspension or load beam is the end that is supported, i.e., the end closest to a base plate that is swaged or otherwise attached to an 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 cantilever end.

[0018] The suspension 105 is coupled to an actuator arm 103. The actuator arm 103 is coupled to a voice coil motor 110. The voice coil motor 110 is configured to move the suspension 105 in an arc to position the head slider over the correct data track of the magnetic disk 101. The head slider is supported on a gimbal (not shown) that allows the slider to pitch and roll to follow the appropriate data track on the rotating magnetic disk 101, thereby accommodating such variations without degrading performance. The variations typically include disk vibrations, inertial events such as collisions, and unevenness in the disk surface.

[0019] Figure 2 is a top view of the suspension 105 of Figure 1. The suspension 105 may include a base plate 12 and a load beam 107. The load beam 107 includes a trace gimbal 152. The trace gimbal 152 may include an attached actuator and a gimbal assembly (not shown). The actuator is operable to directly act on a gimbal region of the suspension 105 that holds a read / write head slider.

[0020] The base plate 12 may include one or more actuator joints 17 configured to receive an actuator 14. The base plate 12 exhibits two actuator joints 17 located on opposite sides of the base plate 12. Each actuator joint 17 includes an actuator mounting shelf 18 formed in a load beam 107. For example, the actuator mounting shelf 18 may extend unitarily from the load beam 107.

[0021] Each actuator 14 spans a respective gap at an actuator joint 17. The actuators 14 are secured to the mounting shelves 18 by adhesive, which may include conductive or non-conductive epoxy 16 appropriately applied to each end of the actuator. Positive and negative electrical connections can be made from the actuators 14 to the flexible wiring traces and / or plates of the suspension 105 by a variety of techniques. When actuated, the actuators 14 expand and contract, finely displacing the read / write heads attached to the distal ends of the suspensions 105, thereby changing the length of the gap between the mounting shelves 18.

[0022] The suspension 105 may be configured as a one-stage actuation suspension, a two-stage actuation system, or a three-stage actuation system. Any variation of actuators may be incorporated into the suspension 105 of the embodiments disclosed herein. In other words, the suspension 105 may include more or less components than those shown without departing from the scope of the present disclosure. However, the components shown are sufficient to disclose an exemplary embodiment for implementing the disclosed principles.

[0023] FIG. 3 illustrates an actuator joint 117 of a suspension 205 according to an example of the present disclosure. The suspension 205 includes a base plate 112 and a load beam 107. The load beam 107 may include a mounting shelf 118. The base plate 112 may include two extensions having opposing base plate edges 111. The mounting shelf 118 may be exposed between the base plate edges 111 such that the distance between the opposing edges of the mounting shelf 118 is less than the distance between the base plate edges 111. The actuator joint 117 is disposed between the base plate 112 and the load beam 107. An actuator 114 is received in the actuator joint 117 between the two base plate edges 111 and rests on the mounting shelf 118 of the load beam 107. The actuator 114 is spaced from one of the two base plate edges 111 by a gap 102. The dimensions of the gap 102 are configured to compensate for various manufacturing factors, such as, for example, placement characteristics of the actuator 114, application characteristics of the adhesive 116, and other manufacturing tolerances. In some manufacturing processes, the adhesive 116 is first applied to the mounting shelf 118 before the actuator 114 is positioned and installed within the actuator joint 117.

[0024] The size of the gap 102 between the actuator 114 and one of the two base plate edges 111 is also configured to compensate for the stiffness of the actuator joint 117. It has been found that an actuator 114 with a smaller gap 102, and therefore a larger cross section, is preferred to increase the stiffness of the suspension 205 due to reduced adhesive. Figure 4 shows the actuator joint 117 without the actuator. Table 1 shows example gaps with different dimensions and associated suspension performance.

[0025] [Table 1] Table 1 shows nominal gap dimensions that are typically limited by manufacturing capabilities such as adhesive application and spreading control. Gaps with small dimensions (less than 100 μm) increase the likelihood of adhesive 116 overflowing toward the opening in the load beam 107, as shown in FIG. 3. This disclosure shows additional examples of actuator joints configured to reduce the likelihood of adhesive 116 overflowing while still improving stiffness.

[0026] 5A illustrates an actuator joint 317 of a suspension 305 according to one example of the present disclosure. The suspension 305 includes a base plate 312 and a load beam 307. The base plate 312 includes a distal elongate element 312A and a proximal elongate element 312B. The distal elongate element 312A and the proximal elongate element 312B may be separated by an actuator receiving space 312C. The load beam 307 includes a mounting shelf 318. A first mounting shelf 318A is coupled to the distal elongate element 312A and a second mounting shelf 318B is coupled to the proximal elongate element 312B. An actuator 314 is received in the actuator joint 317 between the distal elongate element 312A and the proximal elongate element 312B of the base plate 312 and rests on the mounting shelf 318 of the load beam 307.

[0027] An actuator joint 317 is formed between the distal elongate element 312A and the proximal elongate element 312B of the base plate 312 and the mounting shelf 318 of the load beam 307. The distal elongate element 312A of the base plate 312 may be configured to have a non-linear base plate edge 311 of the actuator joint 317.

[0028] The proximal elongate element 312B is also configured to have a non-linear baseplate edge 311. For example, the non-linear edge may include one or more non-linear elements, such as, for example, a concave portion, a convex portion, a beveled portion, a cambered portion, or a portion that does not coincide with another section of the edge. The concave edge 315 is shown herein as being centrally located along the non-linear baseplate edge 311. The dimensions of the concave edge 315 may be configured to reduce overflow of the adhesive 316. Additionally, the actuator joint 317 may be configured such that the non-linear baseplate edge 311 includes one or more linear baseplate edges 313 adjacent the concave edge 315.

[0029] In some examples, the concave edge 315 is centrally located along the edge of the actuator 314. The actuator joint 317 also includes a gap 302 between the edge of the actuator 314 and the non-linear baseplate edge 311 to improve stiffness, as shown in Table 2.

[0030] The dimensions of the recessed edge 315 are typically limited by various manufacturing factors, such as, for example, actuator placement characteristics, adhesive application characteristics, etc. During manufacturing, the adhesive 316 may be first applied to the mounting shelf 318 before the actuator 114 is positioned and installed within the actuator joint 317.

[0031] [Table 2] Table 2 shows example gaps of different dimensions including a non-linear baseplate edge, as well as the stroke and rocking frequency of a suspension incorporating the gap dimensions. A recessed edge 315 may be placed along the non-linear baseplate edge 311 to reduce the possibility of adhesive 316 overflowing.

[0032] The combination of linear and non-linear elements along the non-linear base plate edge 311 provides a better mechanical bond of the adhesive 316 to the base plate 312. The linear and non-linear elements have characteristics that improve adhesion of the adhesive. The non-linear elements allow for a larger cross-section of the adhesive, which results in improved internal strength of the adhesive. In certain embodiments, the internal strength of the adhesive is improved at the concave edge 315. The overall strength of the actuator joint 317 is increased due to the increased internal strength of the adhesive.

[0033] Figure 5B shows the actuator joint 317 without the actuator shown in Figure 5A. The adhesive along the linear elements of the non-linear baseplate edge 311 protrudes between the actuator and the baseplate when the actuator is attached, and the adhesive overflows at the bottom surface of the actuator. Although adhesive overflow has traditionally been used to provide additional mechanical strength to the actuator joint, the adhesive overflow can short out the actuator 314 if it contains conductive particles and extends to the conductive top surface.

[0034] Previously, more adhesive was desired to reduce the likelihood of a faulty bond pad condition. As the amount of adhesive increases to ensure a full bond pad, the number of potentially faulty adhesive overflows also increases. A decrease in the amount of adhesive can result in an increase in faulty bond pads. The present disclosure allows for greater tolerance in applying the adhesive to ensure full bond pads while reducing adhesive overflow. Specifically, the non-linear base plate edge is configured to receive the amount of adhesive that was previously tolerated as adhesive overflow.

[0035] The maximum adhesive overflow height tolerance is specified for the manufacture of the disclosed components to achieve additional mechanical strength. The present disclosure allows for greater tolerance in applying the adhesive to ensure that the maximum adhesive overflow height tolerance is not exceeded for each component. The gap dimensions provide additional mechanical strength previously obtained with adhesive overflow.

[0036] The present disclosure seeks to reduce adhesive overflow, as do the adhesive adhesion-enhancing features disclosed herein, countering the loss of strength caused by eliminating or reducing adhesive overflow with the additional strength provided by the adhesive adhesion-enhancing features.

[0037] FIG 6 illustrates a gimbal assembly 452 of the suspension 500 incorporating an exemplary non-straight edge actuator joint 460. FIG 7 illustrates a cross-sectional view of a region of the actuator 414 taken along section line B-B' of FIG 6. Referring to FIG 7, the actuator 414 spans the receiving area 605. The actuator 414 has a fixed end A and a hinged end B. Each end of the actuator 414 is joined to the gimbal assembly 452 of FIG 6.

[0038] The actuator 414 includes a first electrode 701 on a top surface of the actuator 414 and a second electrode 702 on a bottom surface of the actuator 414. The actuator 414 region hinge end B includes a cover layer 660, a conductive layer 680 (e.g., copper), an insulating layer 690 (e.g., polyimide), and a metal base layer 650 (e.g., stainless steel). The second electrode 702 is electrically coupled to the conductive layer 680 by a conductive adhesive 670. The metal base layer 650 may be configured to incorporate a non-linear stainless steel edge, such as the non-linear base plate edge described herein with reference to FIG. 6. The non-linear stainless steel edge allows for a gap 602. The gap 602 reduces the possibility of an electrical short between the conductive adhesive 670 and the metal base layer 650. A non-conductive adhesive 630 is applied to fill the gap 602.

[0039] At fixed end A, the first electrode 701 is electrically coupled to the conductive layer 680 by conductive adhesive 670. The upper and lower electrodes are separated at fixed end A by non-conductive adhesive 630.

[0040] Although multiple embodiments have been disclosed, further embodiments within the scope of the present disclosure will become apparent to those skilled in the art from the detailed description set forth herein, which shows and describes exemplary embodiments. Accordingly, the drawings and detailed description should be considered as illustrative in nature and not restrictive. Features and modifications of the various embodiments have been discussed herein and shown in the drawings. Although multiple embodiments have been disclosed, further embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes exemplary embodiments of the present disclosure. Accordingly, the drawings and detailed description should be considered as illustrative in nature and not restrictive.

Claims

1. A suspension, a base plate including a distal elongate element and a proximal elongate element, the distal elongate element including one or more non-linear base plate edges, the proximal elongate element including one or more non-linear base plate edges, at least one of the distal elongate element base plate edge and the proximal elongate element base plate edge including a recess near a top surface of the actuator to reduce adhesive overflow; a load beam coupled to the base plate such that a first mounting shelf is exposed adjacent the distal elongate element and a second mounting shelf is exposed adjacent the proximal elongate element, the first mounting shelf having a portion that extends to a receiving portion of the distal elongate element and the second mounting shelf having a portion that extends to a receiving portion of the proximal elongate element, the first mounting shelf and the second mounting shelf being configured to receive the actuator such that an edge of the actuator and one or more of the non-linear base plate edges form a gap; the gap is configured to receive a first adhesive; a load beam, the first adhesive being a non-conductive adhesive or a conductive adhesive; Equipped with a suspension.

2. The suspension of claim 1 , wherein the gap is filled with a first adhesive.

3. The suspension of claim 2 , wherein the one or more non-linear baseplate edges improve tolerances associated with placement of the actuator and application of the first adhesive.

4. The suspension of claim 1 , wherein the one or more non-linear baseplate edges of the distal elongate element include one or more linear baseplate edges.

5. The suspension of claim 1 , wherein the one or more non-linear baseplate edges of the proximal elongate element include one or more linear baseplate edges.

6. A base plate, a distal elongate element including one or more non-linear baseplate edges; a proximal elongate element spaced from the distal elongate element by an actuator receiving space, the proximal elongate element including one or more non-linear baseplate edges; Equipped with at least one of the distal elongate element base plate edge and the proximal elongate element base plate edge includes a recess near a top surface of the actuator to reduce adhesive overflow; the distal elongate element includes a receiving portion therein; The proximal elongate element includes a receiving portion within the proximal elongate element.

7. The baseplate of claim 6 , wherein the one or more non-linear baseplate edges of the distal elongate element include one or more linear baseplate edges.

8. The baseplate of claim 6 , wherein the one or more non-linear baseplate edges of the proximal elongate elements include one or more linear baseplate edges.

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