Patent Application
20220415347
The disclosure relates to a suspension assembly for a hard disk drive.
Hard disk drives (HDDs) utilize a slider to read and write data on magnetic storage media. Typically, the slider is mounted to a free end of a suspension assembly that in turn is cantilevered from the arm of a rotary actuator mounted on a stationary pivot shaft. In some examples, the suspension assembly has a base plate that attaches to the actuator arm and a load beam that extends from the base plate to the free end of the suspension assembly where a slider is mounted on a flexure, thus enabling the slider to actuate about a center of rotation. Position control of the slider relative to data tracks on the spinning magnetic disk medium is limited by the inertial excitation loads induced in the actuator arm as the head is actuated by the suspension assembly. Such torque and lateral loads can result in unwanted excitation of actuator arm sway and torsion modes which in turn can cause an unwanted lateral displacement of the slider.
The present disclosure describes a head suspension assembly (I-ISA) for a hard disk drive. The HSA includes a coupler piece connected to the base plate and the load beam of a head gimbal assembly (HGA). The coupler piece may be manufactured by an etching process or by a stamping process or by other methods of manufacture. Etching the coupler piece may allow for greater precision of coupler piece geometry than stamping the coupler piece. Including an etched coupler piece between the base plate and the load beam of the HGA may allow for better tuning and improvement of the frequency response of the HGA and HSA by potentially reducing the amount of excitation of sway and torsion modes in the HGA. Reducing the gain in the sway and torsion modes may improve the ability of the HGA to accurately position the slider, which may enable the slider to more accurately read and write data on the magnetic media.
In one example, a method of manufacturing a head suspension assembly for a hard disk drive includes applying a resist mask pattern onto a coupler piece, where the resist mask pattern defines an aperture in the coupler piece. The aperture has dimensions large enough to enable a plurality of actuators to fit within said aperture. The method includes etching the coupler piece into the shape of the resist mask and removing the resist mask after patterning.
These and other features and aspects of various examples may be understood in view of the following detailed discussion and accompanying drawings.
HSA 101 includes a voice coil drive actuator 120, an actuator mechanism 116, shaft 118, a plurality of rotatable drive actuator arms 112, and a plurality of head gimbal assemblies 108. Drive actuator arm 112 together with head gimbal assembly 108 forms head suspension assembly 110. Voice coil drive actuator 120 is controlled by servo control circuitry. Voice coil drive actuator 120 is configured to rotate actuator mechanism 116 about shaft 118 in either rotational direction. Drive actuator arms 112 are each coupled to a respective HGA of HGAs 108, such that rotating actuator mechanism 116 causes drive actuator arms 112 and HGAs 108 to move relative to magnetic media 102. Each HGA 108 includes a respective slider 104. Positioning HGAs 108, and thus sliders 104, over the surfaces of magnetic media 102, between inner diameters 122 and outer diameters 124 of magnetic media 102, enables sliders 104 to read data from and write data to magnetic media 102. In some examples, sliders 104 are themselves aerodynamically designed to fly on an air bearing that is created adjacent to each disk surface during disk rotation.
Head gimbal assembly 210 is mounted on drive actuator arm 202. Head gimbal assembly includes a load beam 214, a coupler piece 211 and a base plate 212.
Load beam 214 includes slider 216 which is attached to one end of load beam 214. Slider 216 is used to hold a read/write head that reads and/or writes data from storage media (e.g., magnetic media 102 of
In the example of
In another example, during actual operation of the head suspension assembly 200 for any given read/write operation, when the drive actuator arm 202 swivels in the clockwise direction, the load beam 214 swivels in the counter-clockwise direction. In an alternate implementation, both the drive actuator arm 202 and the load beam 214 swivel in the same direction for an operation, with the displacements of the drive actuator arm 202 and the load beam 214 being out of phase with each other. In yet another example, the swivel movements of the drive actuator arm 202 and the load beam 214 are both in opposite directions and out of phase with each other.
Actuation of the head suspension assembly induces translational inertial (or off-track) and rotational inertial loads on the head suspension assembly. In an out of phase implementation, the inertial loads induce torque about the longitudinal axis, the axis passing through the center of the actuator pivot location 206 and the center of the attachment point 222. In an in-phase implementation, the translational loads induce translational loads to the drive actuator arm 202.
Base plate 302 includes an attachment structure 322, such as a boss tower, configured to couple base plate 302 to drive actuator arm 202 of
Load beam 314 is mechanically coupled to base plate 302 and coupler piece 316. In one example, load beam 314 extends under base plate 302 and under coupler piece 316 to the tip of the head gimbal assembly. In some examples, a top surface of load beam 314 is coupled to a bottom surface of base plate 302 via welding (e.g., laser welding) at weld points 324. In the example of
In some examples, head gimbal assembly 300 includes coupler piece 316. Coupler piece 316 may include a ferrite (e.g., stainless steel) or other suitable material. Coupler piece 316 includes aperture 328. Coupler piece 316 may be manufactured via a stamping process (which may also be referred to as a pressing process) and/or an etching process.
The etching process includes a first step of applying a resist mask pattern onto a top surface of coupler piece 316. The resist mask pattern may be formed by a variety of known techniques. In some examples, a patterned layer may be formed using photolithography. Photolithography uses light to transfer a pattern from a photomask to a light-sensitive photoresist. The resist mask pattern defines aperture 328. After formation of the pattern in the photoresist mask, coupler piece 316 may be exposed to an etching process. During the etching process, any area on the top surface of coupler piece which is not covered by photoresist is removed and aperture 328 is etched into coupler piece 316. Following the etching process, the remaining photoresist is removed from the top surface of coupler piece 316.
In some examples coupler piece 316 may be a stamped coupler piece whereby aperture 328 is etched by an etching process. In other examples, coupler piece 316 may be formed via an etching process only or coupler piece 316 may be formed via a stamping process only.
In the example of
As shown in the example of
While voice coil drive actuator 120 of
Head gimbal assembly 400 is an example of head gimbal assembly 300 of
In one example, base plate 402 is swage-mounted to a drive actuator arm using attachment structure 422. Attachment structure 422 is connected to attachment point 222 on drive actuator arm 202. In some examples, base plate 402 includes region 403 and region 404. Region 403 and region 404 each include a top surface and a bottom surface. A bottom surface of region 403 is mechanically coupled to a top surface of load beam 414 (e.g., via weld points 424).
In some examples, coupler piece 416 includes overhang region 430 and actuation region 405. A bottom surface of actuation region 405 is coupled to a top surface of load beam 414. Actuation region 405 may be thicker than overhang region 430. In the example of
Coupler piece 416 extends from the region 404 of base plate 402 on top of load beam 414 toward the distal end 450 of head gimbal assembly 400. In the example of
In the example of
Load beam 414 is mechanically coupled to base plate 402 and coupler piece 416. In some examples, load beam 414 may share the same footprint as coupler piece 416 in actuation region 405. That is, load beam 414 may include an aperture that overlaps aperture 428 of coupler piece 416. In some examples, the apertures overlap such that, when viewed from above as shown in
Base plate 402 and/or coupler piece 416 may be manufactured via a stamping process. In some examples, stamping base plate 402 and/or coupler piece 416 may limit the manufacture of small feature sizes and may also lead to deformation of parts manufactured using this process.
In some examples, coupler piece 416 may be manufactured separately to base plate 402. In one example, coupler piece 416 may be manufactured using an etching process. Using an etching process in the manufacture of coupler piece 416 may allow for finer tuning of features (e.g., aperture width WAP) in coupler piece 416.
In some examples, coupler piece 416 is configured such that the center of mass of the moving components of the assembly during actuation may be located at approximately the same location as the center of rotation of load beam 414. Moving the center of mass of the moving components of the assembly during actuation closer to the center of rotation of load beam 414 may improve the frequency response of the drive actuator arm sway and drive actuator arm torsion modes in the head stack assembly (e.g., HSA 101 of
Head gimbal assembly 500 is an example of head gimbal assembly 300 of
In one example, base plate 502 is swage-mounted to a drive actuator arm using attachment structure 522. Attachment structure 522 is connected to attachment point 222 on drive actuator arm 202. In some examples, base plate 502 includes region 503 and region 504. Region 503 and region 504 each include a top surface and a bottom surface. A bottom surface of region 503 is mechanically coupled to a top surface of load beam 514 (e.g., via weld points 524).
In some examples, base plate 502 includes overhang region 530 and coupler piece 516 includes actuation region 505. In the example of
Coupler piece 516 extends from region 504 of base plate 502 on top of load beam 514 toward the distal end 550 of head gimbal assembly 500. In the example of
In the example of
Load beam 514 is mechanically coupled to base plate 502 and mechanically coupled to coupler piece 516. In some examples, load beam 514 may share the same footprint as coupler piece 516 in actuation region 505. In some examples the apertures overlap such that, when viewed from above as shown in
Base plate 502, load beam 514 and/or coupler piece 516, may be manufactured via a stamping process. In some examples, stamping base plate 502, load beam 514 and/or coupler piece 516 may limit the manufacture of small feature sizes and may also lead to deformation of parts manufactured using this process. In some examples, coupler piece 516 may be manufactured separately to base plate 502. In one example, coupler piece 516 may be manufactured using an etching process. Using an etching process in the manufacture of coupler piece 516 may allow for finer tuning of features (e.g., aperture width WAP) in coupler piece 516. In some examples, a thinner coupler piece is easier to etch than a thicker coupler piece.
In some examples, coupler piece 516 is configured such that center of mass of the moving components of the assembly during actuation may be located at approximately the same location as the center of rotation of load beam. Moving the center of mass of the moving components of the assembly during actuation closer to the center of rotation of load beam 514 may improve the frequency response of the drive actuator arm sway and drive actuator arm torsion modes in the head stack assembly (e.g., HSA 101 of
Head gimbal assembly 600 is an example of head gimbal assembly 500 of
In the example of
In some examples, it may be possible to reduce the out-of-plane motion of HGA 600 by constraining actuators 608 via a constraining layer. In the example of
In the example of
A resist mask pattern may be formed by a variety of known techniques. In some embodiments, a resist mask pattern may be formed using photolithography. Photolithography uses light to transfer a pattern from a photo-mask to light-sensitive photoresist. The resist mask pattern is provided to protect the masked portion of the coupler piece from the removal process that occurs during etching of the coupler piece.
Following the application of the resist mask pattern onto coupler piece, the coupler piece is etched into the shape of the resist mask (703). During the etching process, any portion of the coupler piece not covered by the resist mask will be etched by the etching process. Examples of etching processes include reactive ion etching (RIE) or plasma etching.
Following the etching process, any remaining resist mask pattern is removed (705).
In the example of
Following the coupling of coupler piece to the load beam and base plate, actuators, such as actuators 308 of
Various examples have been presented for the purposes of illustration and description. These and other examples are within the scope of the following claims.
