Head gimbal assembly for hard disk drive device

Abstract

To provide a head gimbal assembly for a hard disk drive device.SOLUTION: A gimbal has a base portion and a tongue joined together by a neck portion. The base portion includes a first proximal edge facing away from the tongue. A circuit is mounted on the gimbal and includes a portion mounted to the base portion having a circuit extension region that extends beyond the first proximal edge. The circuit extension region includes a second proximal edge facing away from the tongue. A slider may be mounted on the tongue and electrically connected to the circuit. First and second PZT actuators are mounted to the head gimbal assembly and electrically connected to the circuit. The circuit extension region has a circuit extension region width W of at least 0.1 mm as measured in a direction extending away from the tongue relative to a furthest extending portion of the first proximal edge and a furthest extending portion of the second proximal edge.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Patent Application No. 18 / 212,586, filed June 21, 2023, which is incorporated by reference in its entirety.

[0002] The present invention relates to hard disk drives, and more particularly to head gimbal assemblies and suspension assemblies for hard disk drives. [Background technology]

[0003] A hard disk drive (HDD) is a non-volatile storage device that stores digitally encoded data on one or more circular disks having magnetic surfaces. During operation, each disk rotates at high speed. Data is read from and written to the disks using a read / write head that is positioned at a specific data track or location on the disk surface by a suspension assembly attached to an arm of the head stack assembly that is rotated by a voice coil motor or actuator integrated into the head stack assembly. Stabilizing and aligning the read / write head with a target data track on the disk surface defines the primary function of the suspension assembly during hard disk drive operation. Optimizing the design and manufacture of the suspension assembly can minimize the effects of mechanical, thermal, and other off-track disturbances that can degrade the performance of a hard disk drive. The suspension assembly includes a load beam. During operation, an actuator positions the distal end of the load beam over a desired portion of the disk (e.g., one of the circular tracks on the disk surface). A gimbal assembly (also called a flexure) is attached to the distal end of the load beam. The gimbal assembly may include components such as a slider, which contains the read / write head, and a microactuator device (a piezoelectric device, also referred to herein as a PZT) that rotates a portion of the gimbal assembly for fine positioning of the slider (as opposed to the more coarse positioning of the slider by the actuator). Viscous air pressure between the slider and the spinning disk causes the slider to hover over (in close proximity to) the surface of the disk. The load beam is relatively stiff, especially in the lateral axis, while the gimbal assembly is more flexible, allowing the slider to pitch and roll while floating over the disk surface to maintain its operating distance just above the disk surface.

[0004] FIGURE 1 illustrates a portion of a conventional head stack assembly 2, and FIGURES 2 and 3 illustrate a conventional head gimbal assembly 10 of the head stack assembly 2. The head stack assembly 2 includes a suspension assembly 3 with a load beam 4 terminating at a proximal end with a hinge 6 connected to a base plate 8. Attached to the distal end of the load beam is the head gimbal assembly 10. The base plate 8 is connected to an actuator arm 12 of the head stack assembly 2, which is rotated by an integral actuator (not shown).

[0005] As best shown in Figures 2 and 3, the head gimbal assembly 10 includes a gimbal 14, which is a thin piece of sheet metal (e.g., stainless steel), a circuit 16 including conductive traces (e.g., copper) and an insulating material (e.g., polyimide), a slider 18 having a read / write head attached (e.g., by adhesive) to the gimbal 14, and a PZT actuator 20 attached to the same side of the gimbal 14 as the slider 18. The circuit 16 extends along the load beam 4 and the head gimbal assembly 10 and conveys electrical signals to the read / write head of the slider 18 and to the PZT actuator 20. The conductive traces of the circuit 16 are electrically isolated from the gimbal 14 by the insulating material of the circuit 16.

[0006] The gimbal 14 includes a base portion 14a and a tongue portion 14b, which are connected together by a neck portion 14c. The tongue portion 14b is configured to rotate about the neck portion 14c (for fine position control of the slider 18). The slider 18 is attached to the tongue portion 14b. A PZT actuator 20 is attached between the tongue portion 14b and the base portion 14a and is adapted to rotate the tongue portion 14b about the neck portion 14 when the PZT actuator 20 expands or contracts in response to electrical signals provided by the circuitry 16, thereby providing fine movement control of the slider 18 relative to the disk track during operation. In this example, the PZT actuator 20 is indirectly attached to the gimbal 14; that is, the PZT actuator 20 is attached to the circuitry 16, which is attached to the gimbal 14.

[0007] The PZT actuator 20 may be a multi-layer device of piezoelectric material. A common example of a piezoelectric material is lead zirconate titanate, although other piezoelectric materials are used and known, and expand and contract in response to electronic signals. PZT material may be brittle. When not in use, the suspension assembly 3 may be placed on a ramp to help protect against harmful movement that may be caused by non-operational shock events (e.g., when the HDD is roughly handled or dropped). However, non-operational shock events may damage the head gimbal assembly 10 (e.g., the PZT material may crack and / or the circuitry 16 may permanently deform). Large movements of the base portion 14a in the pitch direction may cause damage because the proximal end of the base portion 14a contacts the load beam 4, causing excessive stress on the PZT actuator 20. Summary of the Invention [Problem to be solved by the invention]

[0008] What is needed is a head gimbal assembly design that is less susceptible to damage from non-operational shock events. [Means for solving the problem]

[0009] The aforementioned problems and needs are addressed by a head gimbal assembly including a gimbal having a base and a tongue joined together by a neck. The base includes a first proximal edge facing away from the tongue, and a circuit is attached to the gimbal. The circuit includes a portion attached to the base and having a circuit extension area that extends beyond the first proximal edge of the base. The circuit extension area includes a second proximal edge facing away from the tongue. A first PZT actuator and a second PZT actuator are attached to the head gimbal assembly and electrically connected to the circuit to displace the tongue relative to the base. The head gimbal assembly can also include a slider attached to the tongue and electrically connected to the circuit. The circuit extension region has a circuit extension region width W of at least 0.1 mm measured in a direction away from the tongue relative to the furthest extending portion of the first proximal edge extending in a direction away from the tongue and the furthest extending portion of the second proximal edge extending in a direction away from the tongue.

[0010] In another embodiment, a suspension assembly is provided generally comprising a base plate, a load beam connected to the base plate by a hinge, and a gimbal attached to the load beam, the gimbal including a base and a tongue joined by a neck, the base including a first proximal edge facing away from the tongue. A circuit is attached to the gimbal. The circuit includes a portion attached to the base having a circuit extension region that extends beyond the first proximal edge of the base. The circuit extension region includes a second proximal edge facing away from the tongue. A first PZT actuator and a second PZT actuator are attached to the suspension assembly and electrically connected to the circuit to displace the tongue relative to the base. The circuit extension region has a circuit extension region width W of at least 0.1 mm measured away from the tongue relative to a furthest extending portion of the first proximal edge extending away from the tongue and a furthest extending portion of the second proximal edge extending away from the tongue.

[0011] Other objects and features of the present disclosure will become apparent from a consideration of the specification, claims, and accompanying drawings. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a partial perspective view of a conventional head suspension assembly. [Diagram 2] FIG. 1 is a bottom view of a conventional head suspension assembly. [Diagram 3] FIG. 1 is a top view of a conventional head suspension assembly. [Figure 4] FIG. 2 is a top view of an example of a head gimbal assembly according to some embodiments of the present disclosure. [Diagram 5] FIG. 2 is a bottom view of an example of a head gimbal assembly according to some embodiments of the present disclosure. [Figure 6] 6 is a graphical representation of PZT maximum stress as a function of circuit extension region width W of the head gimbal assembly of FIGS. 4 and 5. [Figure 7] FIG. 13 is a top view of a second example of a head gimbal assembly according to some embodiments of the present disclosure. [Figure 8] FIG. 13 is a top view of a third example of a head gimbal assembly according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The inventors have discovered that by providing a circuit extension region that extends the circuitry beyond the proximal edge of the base of the gimbal by at least a certain width dimension, the stress on the PZT actuator during a non-operating shock event is significantly reduced. Such a gimbal may be used with the head stack assembly 2 shown in FIG.

[0014] 4 and 5 show top and bottom views, respectively, of a head gimbal assembly 30 according to one embodiment, which is compatible with the head stack assembly 2 and suspension assembly 3 described above (i.e., the head gimbal assembly 30 can be attached to the load beam 4 described above with respect to FIG. 1). The head gimbal assembly 30 includes a gimbal 32 forming a thin piece of sheet metal. The gimbal 32 can be formed of stainless steel. A circuit 34 is mounted or otherwise attached to the gimbal 32 and includes conductive traces and insulating material. The conductive traces can be copper and the insulating material can be polyimide. A slider 36 is attached to the gimbal 32 and includes a read / write head. The slider 36 can be attached to the gimbal 32 by an adhesive.

[0015] The gimbal 32 includes a base portion 32a and a tongue portion 32b, which are joined by a neck portion 32c. A slider 36 is attached to the tongue portion 32b (either directly to the tongue or indirectly to the tongue with the slider 36 attached directly to the circuitry 34 and the circuitry 34 attached directly to the tongue portion 32b such that the circuitry 34 is disposed between the slider 36 and the tongue portion 32b). The tongue portion 32b is configured to rotate or otherwise displace relative to the base portion 32a about the neck portion 32c to provide relatively small movements of the slider 36 for fine positional control of the slider 36 during operation. A PZT actuator 38 is mounted between the tongue 32b and the base 32a so that, as the PZT actuator 38 extends or contracts in response to electrical signals provided by the circuit 34, it rotates or otherwise displaces the tongue 32b (and the slider 36 attached to the tongue 32b) relative to the base 32a about the neck 32c (to provide fine positioning control of the slider 36 relative to the disk track during operation).

[0016] The circuit 34, slider 36, and PZT actuator 38 can all be attached to the same side (i.e., the first or bottom side) of the gimbal 32. Alternatively, as shown in FIGS. 4 and 5, the circuit 34 and slider 36 can be attached to the first side of the gimbal 32 while the PZT actuator 38 is attached to the opposite side (i.e., the second or top side) of the gimbal 32. In this example, the PZT actuator 38 is indirectly attached to the gimbal 32. That is, the PZT actuator 38 is attached to a bonding site 34a / 34b of the circuit 34, which is attached to the gimbal 32. Specifically, the bonding site 34a is the portion of the circuit 34 where the proximal end of the PZT actuator 38 is attached (adjacent to the base portion 32a) and the bonding site 34b is the portion of the circuit 34 where the distal end of the PZT actuator 38 is attached (adjacent to the tongue portion 32b). Thus, the expansion and contraction force of the PZT actuator 38 used to displace the tongue 32b is transmitted through the circuit 34 to the base 32a and to the tongue 32b.

[0017] Circuitry 34 extends along and is attached to gimbal 32, and transmits electrical signals to and from the read / write head of slider 36, and to a PZT actuator 38 for fine positioning control of slider 36. Thus, circuitry 34 is electrically connected to the electrodes of PZT actuator 38 (to provide signals to expand and contract the PZT actuator) and to slider 36 (to transmit signals to and from slider 36 to perform operations such as reading and writing).

[0018] The inventors have discovered that a significant reduction in maximum stress on the PZT actuator 38 and the remainder of the head gimbal assembly 30 during a non-operational shock event can be achieved by having the portion of the circuit 34 attached to the base portion 32a include a circuit extension region 34c, which is the portion of the circuit 34 that extends beyond the first proximal edge 40 of the base portion 32a, and the circuit extension region 34c has a circuit extension region width W of at least 0.1 mm. The circuit extension region width W is the width of the circuit extension region 34c (measured in a direction away from the tongue 32b) relative to the furthest extending portion of the first proximal edge 40 of the base portion 32a (in a direction away from the tongue 32b) and the furthest extending portion of the second proximal edge 42 of the circuit extension region 34c (in a direction away from the tongue 32b). Both the first proximal edge 40 and the second proximal edge 42 face away from the tongue 32b. The circuit extension region 34c includes the insulating material of the circuit 34, but does not include the electrical traces of the circuit 34. Better performance is provided by having the circuit extension region 34c include only the more flexible insulating material, and not the more rigid electrical traces.

[0019] FIG. 6 shows the relationship between the maximum stress on the PZT actuator due to a non-operational shock versus the circuit extension region width W, and the inventors have discovered that when the circuit extension region width W reaches at least 0.1 mm, the maximum stress is significantly and unexpectedly reduced. This reduction in maximum stress is due to the fact that the insulating material of the circuit 34 is more flexible than the gimbal 32, so that if the circuit extension region width W is large enough, there is enough insulating material of the circuit 34 to contact the load beam and absorb the impact energy between the gimbal assembly 30 and the load beam 4 in a non-operational shock event, thereby significantly reducing the stress caused to the PZT actuator 38. If the circuit extension region width W is 0.1 mm or more, a significant shock reduction advantage is obtained. Therefore, by including a circuit extension region 34c having a circuit extension region width W of at least 0.1 mm, the maximum stress due to a non-operational shock event can be significantly reduced, and damage to the PZT actuator and / or the head gimbal assembly 30 can be avoided.

[0020] In the example of FIG. 6, the proximal edge 40 of the base portion 32a is not straight, but the proximal edge 42 of the circuit extension region 34c is substantially straight. However, the proximal edge 42 of the circuit extension region 34c need not be substantially straight. FIG. 7 is a second example of a head gimbal assembly 30 in which the proximal edge 42 of the circuit extension region 34c is not straight, but instead includes a notch 44, which is desirable so as not to interfere with the alignment function of the load beam 4. FIG. 8 is a third example of a head gimbal assembly in which the furthest extending portion of the first proximal edge 40 of the base portion 32a (in a direction away from the tongue 32b) is offset from the furthest extending portion of the second proximal edge 42 of the circuit extension region 34c (in a direction away from the tongue 32b).

[0021] It should be understood that the present disclosure is not limited to the examples described above and illustrated herein, but encompasses any and all variations falling within the scope of any claim. For example, references to the invention, embodiments or examples herein are not intended to limit the scope of any claim or claim term, but are instead intended to refer to one or more features that may be covered by one or more of the claims. The materials, processes and numerical examples described above are merely illustrative and should not be considered as limiting the scope of the claims.

Claims

1. A head gimbal assembly, a gimbal having a base and a tongue joined by a neck, the base including a first proximal edge facing away from the tongue; a circuit attached to the gimbal, the circuit including a portion attached to the base including a circuit extension region that extends beyond a first proximal edge of the base, the circuit extension region including a second proximal edge that faces away from the tongue; a first PZT actuator and a second PZT actuator attached to a head gimbal assembly and electrically connected to the circuit for displacing the tongue portion relative to the base portion; A head gimbal assembly, wherein the circuit extension region has a circuit extension region width W of at least 0.1 mm measured in a direction away from the tongue relative to a furthest extending portion of a first proximal edge extending in a direction away from the tongue and a furthest extending portion of a second proximal edge extending in a direction away from the tongue.

2. 2. The head gimbal assembly of claim 1, wherein the circuit includes electrical traces and insulating material, and a circuit extension area of ​​the circuit includes insulating material without electrical traces.

3. the first PZT actuator having a proximal end attached to a first junction of the circuit and a distal end attached to a second junction of the circuit; 2. The head gimbal assembly of claim 1, wherein the second PZT actuator has a proximal end attached to a third junction of the circuit and a distal end attached to a fourth junction of the circuit.

4. The head gimbal assembly of claim 3 , wherein the first and third joint sites are adjacent to the base portion, and the second and fourth joint sites are adjacent to the tongue portion.

5. The head gimbal assembly of claim 1 , further comprising a slider attached to the tongue and electrically connected to the circuit.

6. 6. The head gimbal assembly of claim 5, wherein the circuit is disposed between the slider and the tongue.

7. 1. A suspension assembly comprising: A base plate; a load beam connected to the base plate by a hinge; a gimbal attached to the load beam, the gimbal comprising a base and a tongue joined by a neck, the base including a first proximal edge facing away from the tongue; a circuit attached to the gimbal, the circuit including a portion attached to the base including a circuit extension region that extends beyond a first proximal edge of the base, the circuit extension region including a second proximal edge that faces away from the tongue; a first PZT actuator and a second PZT actuator attached to a suspension assembly and electrically connected to the circuit to displace the tongue relative to the base; the circuit extension region has a circuit extension region width W of at least 0.1 mm measured in a direction away from the tongue relative to a furthest extending portion of a first proximal edge extending in a direction away from the tongue and a furthest extending portion of a second proximal edge extending in a direction away from the tongue.

8. 8. The suspension assembly of claim 7, wherein the circuit includes electrical traces and insulating material, and a circuit extension area of ​​the circuit includes insulating material without electrical traces.

9. the first PZT actuator having a proximal end attached to a first junction of the circuit and a distal end attached to a second junction of the circuit; 8. The suspension assembly of claim 7, wherein the second PZT actuator has a proximal end attached to a third junction of the circuit and a distal end attached to a fourth junction of the circuit.

10. 10. The suspension assembly of claim 9, wherein the first bond site and the third bond site are adjacent to the base portion, and the second bond site and the fourth bond site are adjacent to the tongue portion.

11. The suspension assembly of claim 7 , further comprising a slider attached to said tongue and electrically connected to said circuit.

12. The suspension assembly of claim 11 , wherein the circuit is disposed between the slider and the tongue.

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