Multi-disk pack stacking structure for hard disk drives

Abstract

To provide a hard disk drive (HDD) with a large capacity that increases the number of disks in a prescribed form factor and improves performance.SOLUTION: A multi-disk pack system 300 includes a first spindle motor assembly 302 mounted one above the other on a base platform 307 and a second spindle motor assembly 304. Each motor assembly may include a small axial directional flux motor. A first electric wire 302w and a second electric wire 304w for each motor are routed to an electric connector 313 at a base post within a structural cutout 306c feature part of a base post 306. To further reduce the vertical height of the multi-disk pack assembly, compact threaded disk clamps 302c, 304c, and motor hubs (fluid dynamic bearings 302b, 304b, and hubs 302h, 304h) are implemented.SELECTED DRAWING: Figure 3A

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the invention may relate generally to data storage devices, and more particularly to hard disk drives having multiple disk stacks. [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 that are housed in a protective enclosure and have magnetic surfaces. When an HDD is in operation, each magnetic recording disk is rapidly rotated by a spindle system. Data is read from and written to the magnetic recording disks using a read-write head (or "transducer") housed on a slider that is positioned over specific locations on the disks by an actuator. The read-write head uses a magnetic field to write data to and read data from the surface of the magnetic recording disk. The write head works by generating a magnetic field using an electric current that flows through the coil of the write head. Electrical pulses are sent to the write head with different patterns of positive and negative currents. The electric current in the coil of the write head creates a localized magnetic field across the gap between the head and the magnetic recording disk, which in turn magnetizes small areas on the recording medium.

[0003] Increasing areal density (a measure of the amount of information bits that can be stored in a given area of ​​the disk surface) is one of the ongoing goals of hard disk drive technology evolution. In one form, this goal is manifested in the types of high-capacity HDDs that are particularly attractive in the context of enterprise, cloud computing / storage, and data center environments. However, the performance of high-capacity HDDs has not necessarily scaled up in proportion to the increase in capacity. This has led to the need to develop and implement various means to improve the performance of high-capacity HDDs, shifting some of the burden to the mechanics. One approach to the above is to increase the number of disks within a prescribed form factor. Since these HDDs are primarily used for near-line storage in data centers in hyperscale environments, the performance of these high-capacity drives must also meet density requirements in Input / Output Operations Per Second (IOPs) (in some cases also referred to as IOPs / TB) to minimize latency. This demand has led to a shift to multiple actuators to provide parallel access to data.

[0004] The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Thus, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. [Brief description of the drawings]

[0005] Embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numbers refer to similar elements and in which:

[0006] [Figure 1] 1 is a plan view showing a hard disk drive (HDD) according to an embodiment. [Diagram 2] FIG. 2 is a side cross-sectional view of a dual actuator according to an embodiment. [Figure 3A] 1 is a side cross-sectional view showing an HDD multi-disk pack system according to an embodiment. [Figure 3B] FIG. 3B is an exploded cross-sectional side view of the multi-disk pack system of FIG. 3A, according to an embodiment. [Figure 4] FIG. 3B is an exploded cross-sectional perspective view further illustrating the HDD multi-disk pack system of FIG. 3A, according to an embodiment. [Figure 5A] FIG. 1 illustrates a side view of an axial flux motor, according to an embodiment. [Figure 5B] FIG. 5B is a cross-sectional plan view of the axial flux motor of FIG. 5A, according to an embodiment. [Figure 6] 6A and 6B are side cross-sectional views of a disk clamp of the disk pack of FIG. 3A and a portion of the disk clamp of FIG. 6A, according to an embodiment. [Figure 7] 4 is a flow diagram illustrating a method for assembling a multi-disk pack hard disk drive, according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Generally, an approach to a multiple spindle motor hard disk drive (HDD) is described. The term "spindle motor" is used herein in reference to a recording disk media spindle motor assembly configured to rotate the disk media for data read (and possibly write) operations, such as the drive motor described with reference to FIG. 1. In the following specification, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention described herein. However, it will be apparent that the embodiments of the invention described herein may be practiced without these specific details. In other instances, well-known structures and devices are represented in block diagram form in order to avoid unnecessarily obscuring the embodiments of the invention described herein. introduction term

[0008] References herein to "an embodiment," "one embodiment," and the like are intended to mean that the particular feature, structure, or characteristic being described is included in at least one embodiment of the invention. However, instances of such phrases do not necessarily all refer to the same embodiment.

[0009] It will be understood that the term "substantially" describes features that are largely or approximately structured, configured, dimensioned, etc., however, that manufacturing tolerances and the like may result in situations where in practice the structure, configuration, dimensions, etc. are not always or necessarily precisely as described. For example, if one were to describe a structure as being "substantially vertical," the term would be assigned its obvious meaning such that the sidewalls are for all practical purposes vertical, but may not be at exactly 90 degrees.

[0010] Terms such as "optimal," "optimize," "minimal," "minimize," "maximum," "maximize," and the like may not have a specific value associated with them, but when such terms are used herein, it is intended that one of ordinary skill in the art will understand that such terms include affecting values, parameters, metrics, and the like in a beneficial direction consistent with the entirety of this disclosure. For example, describing some value as a "minimum" does not require that the value actually be equal to a theoretical minimum (e.g., zero), but should be understood in a practical sense in that the corresponding goal would be to move the value in a beneficial direction toward the theoretical minimum. context

[0011] Recall the observation that the performance of large capacity HDDs has not scaled up proportionately with the increase in storage capacity. The high latency of large capacity HDDs in a clustered environment, such as a data center with multiple clustered nodes, results in a bottleneck due to slower access to stored data. As HDD capacities continue to increase, there is more pressure to improve performance (e.g., IOPS) by reducing the latency for data operations in high capacity HDDs. One possible approach to improving HDD performance is the implementation of a multi-actuator system, in which multiple independently operating actuators are assembled, for example, on a single shared pivot shaft, to independently and simultaneously read and / or write from multiple recording disks of a disk stack. However, the embodiments described herein do not depend on a multi-actuator arrangement.

[0012] 2 is a side cross-sectional view of a dual actuator system, according to an embodiment. The generalized actuator system 200 comprises a shaft 202 having a bore 203 at least partially therethrough. According to an embodiment, the shaft 202 is utilized as a pivot shaft or as part of an actuator pivot assembly or shared shaft assembly for multiple actuator components of a multi-actuator data storage device, such as a hard disk drive (HDD). Thus, the actuator system 200 comprises a shaft 202 about which a first or lower rotary actuator assembly 204 (e.g., a voice coil actuator and including a carriage 204a, such as carriage 134 of FIG. 1) is rotatably coupled at a first location on the shaft 202 with a lower bearing assembly 206 therebetween, and a second, upper rotary actuator assembly 205 (e.g., a voice coil actuator and including a carriage 205a, such as carriage 134 of FIG. 1) is rotatably coupled at a second location on the shaft 202 with an upper bearing assembly 207 therebetween. Alternatively, according to an embodiment, the functionality of shaft 202 utilized as a pivot shaft may be implemented using separate shafts, e.g., one shaft for each actuator assembly 204, 205, rather than a shared shaft assembly such as shaft 202. This may isolate undesirable structural dynamic interference associated with independent operation of multiple actuator assemblies, such as actuator assembly 204 and actuator assembly 205, mounted on a single shared shaft. Similar to that shown and described with reference to FIG. 1 for a single actuator HDD, each actuator assembly 204, 205, together with its corresponding head stack assembly (HSA) and head gimbal assembly (HGA), generally can independently and simultaneously read from and / or write to multiple recording disks of the disk stack.

[0013] Furthermore, the need for archival storage is increasing. Tape is a traditional solution for data backup, but accessing data is very slow. Current archives are increasingly becoming "active" archives, which means that a certain level of continuous random read data access is required. Traditional hard disk drives (HDDs) can be used, but the costs may be considered unnecessarily high. Other approaches considered may include HDDs with extra-large diameter disks and HDDs with extra-tall form factors, both of which require, for example, large capital investments due to unique components and assembly processes, low value propositions in the context of cost savings, and barriers to market adoption due to the uniquely large form factor. However, one possible approach includes the standard HDD form factor (e.g., 3.5-inch form factor) and the most common HDD architectures, with n disks in one or more rotating disk stacks, but fewer than 2n read / write heads. Such storage devices may utilize articulating mechanisms that allow the heads to move to mate with different disk surfaces (as non-limiting examples, only two heads except for 5+ disks for Air drives and 8+ disks for He drives), and the primary cost savings may come from eliminating most of the heads in the drive.

[0014] One such approach may include an actuator subsystem that converts rotational motion to linear motion, such as with a stepper motor disposed within a ball screw cam assembly, to form an actuator elevator subassembly that is disposed within an actuator pivot and pivot bearing of the actuator subsystem (e.g., a "pivot cartridge") and configured to vertically translate at least one actuator arm with a respective HGA to access disk media corresponding to one or more disk packs. One such non-limiting approach is described in U.S. Pat. No. 10,811,044 to Myers et al., entitled "In-Pivot Stepper Motor For Ball Screw Cam Elevator Mechanism for Cold Storage Data Storage Device," the entire contents of which are incorporated by reference for all purposes as if fully set forth herein. Another such non-limiting technique is described in U.S. Pat. No. 10,902,871 to Myers et al., entitled "Low-Profile Ball Screw Cam Elevator Mechanism for Cold Storage Data Storage Device," the entire contents of which are incorporated by reference for all purposes as if fully set forth herein. Yet another non-limiting approach involving an elevator platform assembly for moving an actuator assembly is described in Garbarino, U.S. Pat. No. 11,031,037, entitled "System For Disk-To-Disk Access For Reduced-Head Data Storage Device," the entire contents of which are incorporated by reference for all purposes as if fully set forth herein. Multi-Disk Pack System

[0015] FIG. 3A is a cross-sectional side view of a hard disk drive (HDD) according to an embodiment, and FIG. 3B is an exploded cross-sectional side view of the multiple disk pack system of FIG. 3A according to an embodiment. The multi-disk pack system 300 comprises a first (also referred to as "lower" or "bottom") spindle motor assembly 302 and a second (also referred to as "upper" or "top") spindle motor assembly 304, both mounted on a base with a base post 306 extending from a base platform 307, each configured to operate independently of the other. It is noted that this arrangement may also implement additional spindle motor assemblies beyond the two shown, and the number of independent disk packs may or may not be equal to the number of corresponding actuator assemblies implemented. In fact, it is contemplated that the multi-disk pack system 300 may be implemented in a single actuator configuration and still provide advantages over conventional single actuator systems. It is further contemplated that the multi-disk pack system 300 may be implemented using any coordinated control between one or more of the spindle motor assemblies 302, 304 and the actuator elevator subassembly, using an actuator elevator subassembly configuration as referenced elsewhere herein.

[0016] According to an embodiment, each spindle motor assembly 302, 304 includes a corresponding flange and disk clamp. Thus, the first spindle motor assembly 302 includes a first flange 302f, a first motor bracket 302mb, and a first disk clamp 302c, and the second spindle motor assembly 304 includes a second flange 304f, a second motor bracket 304mb, and a second disk clamp 304c. According to an embodiment, the first spindle motor assembly 302 is mounted on a base post 306 such that the first motor bracket 302mb interacts with the base platform 307, and the second spindle motor assembly 304 is mounted on a base post 306 above, above, or on top of the first spindle motor assembly 302 such that the second motor bracket 302mb interacts with the first disk clamp 302c. For example, intermediate structures, such as spacers or dampers or other support components, disposed between the first and second spindle motor assemblies 302, 304 are contemplated to improve structural stability, individual and combined dynamic response, operational shock response, etc. According to an embodiment, each of the first and second spindle motor assemblies 302, 304 comprises a hollow shaft 302s, 304s for mounting on a base post 306, i.e., the base post 306 is disposed through the hollow shaft.

[0017] Generally, each spindle motor assembly 302, 304 is configured as a modular assembly and pre-assembled, for example, with corresponding fluid dynamic bearings 302b, 304b and multiple disk media 303, 305 mounted on hubs 302h, 304h (also called "spindle motor hubs" or "spindle hubs") and separated by spacers 303s, 305s as is common in HDDs. Thus, assembly of multiple spindle motor assemblies 302, 304 onto base post 306 in the illustrated configuration is considered a relatively simple and straightforward process that involves fastening multiple spindle motor assemblies 302, 304 onto a base portion, i.e., base post 306, via screws 308 (FIG. 3B) or any other type of common fastener that is threadably engaged with base post 306 through HDD cover 310 (FIG. 3B).

[0018] However, one challenge with multi-disk pack HDDs is the need to provide power to each of the independent spindle motor assemblies 302, 304, rather than having to implement additional electronics on the top of the HDD, such as electrically connecting the top spindle motor 304 to electronics (e.g., a flexible printed circuit or "FPC 312") coupled to the bottom of the base. According to an embodiment, the system 300 further comprises an electrical connector 313 (FIG. 3B) mechanically coupled to the base and electrically coupled to the FPC 312 (FIG. 3B), the first spindle motor assembly 302 further comprises a first electrical trace 302w routed along the base post 306 to the electrical connector 313, and the second spindle motor assembly 304 further comprises a second electrical trace 304w routed along the base post 306 to the electrical connector 313. According to an embodiment, each of the first and second electrical traces 302w, 304w are routed within a structural cut-out 306c feature (e.g., a recess) in the base post 306, where the remaining space around the traces at the bottom of the base or at the interface area with the base can be filled with an adhesive or other material to provide a hermetic seal if desired.

[0019] FIG. 4 is an exploded cutaway perspective view further illustrating the HDD multi-disk pack system of FIG. 3A, according to an embodiment. FIG. 4 provides an additional view of the multi-disk pack system 300, including a first spindle motor assembly 302 with a first flange 302f and a first disk clamp 302c, holding a first plurality of disk media 303, and a second spindle motor assembly 304 with a second flange 304f and a second disk clamp 304c, holding a second plurality of disk media 305, both mounted on a base post 306 extending from a base platform 307. Again, the first motor bracket 302mb structurally interfaces with the base platform 307, and the second motor bracket 304mb structurally interfaces with the first clamp 302c. Also visible here are the annular threaded receiving features 604t of the first and second spindle motor assemblies 302, 304, the significance of which will be shown and explained in more detail with reference to FIGS. 6A-6B. Axial Flux Electromagnet (AFEM) motor

[0020] According to an embodiment, each of the first and second spindle motor assemblies 302, 304 comprises an axial flux motor. An AFEM (axial flux electromagnetic) motor (sometimes referred to as a "pancake" motor) is a shape of motor structure in which the gap between the rotor and stator, and therefore the direction of the magnetic flux between the two, is aligned parallel to the axis of rotation, rather than radially as in the concentric cylindrical shapes of more common radial flux or radial gap motors. In general, AFEM motors can provide greater electromagnetic torque compared to any conventional radial flux motor for a given electromagnetic volume (e.g., considering the stator stack length and average diameter of the air gap, or power density), have shorter and more direct magnetic flux paths, and better cooling characteristics.

[0021] FIG. 5A is a side view of an axial flux motor, and FIG. 5B is a cross-sectional plan view of the axial flux motor of FIG. 5A, according to an embodiment. The AFEM motor 500 (or simply "motor 500") of FIG. 5A illustrates an exemplary axial flux electromagnet (ic) motor that includes a rotatable / rotatable motor hub 502, a stator 504 having multiple coils 505 wound around corresponding core protrusions, a yoke 506 (e.g., cast iron or steel) for carrying magnetic flux 510 through the magnetic poles, and an axially magnetized ring magnet 508 (e.g., for the rotor). The number of turns and wire gauge of the stator coil 505 can be designed and optimized for a specific electromagnetic torque to meet product minimum requirements according to electrical and magnetic loads. In suitable non-limiting examples, the rotor magnets 508 may be axially magnetized to have 12 poles (with 9 stator slots), 8 poles (with 12 stator slots), 16 poles (with 12 stator slots), with 9 slots shown in the example of FIG. 5B.

[0022] 5B further illustrates the base post 306 surrounded by a spindle motor shaft 500s (see, e.g., hollow shaft 302s, 304s in FIGS. 3A-3B) supported by a motor bracket 500mb (see, e.g., motor brackets 302mb, 304mb in FIGS. 3A-4), with motor electrical wiring 500w (see, e.g., electrical wiring 302w, 304w in FIGS. 3A-3B) routed along a structural cut-out 306c feature of the base post 306 (see, e.g., electrical connector 313 in FIGS. 3A-3B) to an electrical connector 313. Again, since AFEM motors can provide greater electromagnetic torque for a given electromagnetic volume compared to conventional radial flux motors, for example, they provide a preferred and compact implementation in this context, i.e., a spatially efficient stacking of multiple spindle motor assemblies on a shared base post in a high performance multi-disk pack HDD. Threaded Disc Clamp

[0023] Figure 6A is a cross-sectional side view of a disk clamp for the disk pack of Figure 3A, and Figure 6B is an enlarged cross-sectional side view of a portion of the disk clamp of Figure 6A, both according to an embodiment. Considering the need for a compact disk clamp in a vertical orientation (i.e., z-height coinciding with the axis of rotation of the spindle motor), a threaded disk clamp and spindle motor interface is described, according to an embodiment.

[0024] The annular threaded receiving feature 604t of the first and second spindle motor assemblies 302, 304 (FIGS. 3A-4) was previously introduced herein. As shown, the spindle motor hub 604 that may be implemented for the hubs 302h, 304h (FIG. 3A) of the first and second spindle motor assemblies 302, 304, respectively, includes an internal thread on the outer periphery of the annular threaded receiving feature 604t. That is, the hub 604 includes an annular threaded recess or channel, i.e., the threaded receiving feature 604t, having an external thread. This threaded receiving feature 604t serves as a fixed receiver for a corresponding threaded feature of the disk clamp 602. A disk clamp 602, which may be implemented for clamps 302c, 304c (FIGS. 3A, 4) for each of the first and second spindle motor assemblies 302, 304, includes a circumferential thread 602t on the outer periphery of the hub of the disk clamp 602, configured to mechanically mate with a threaded receiving feature 604t of the corresponding spindle motor hub 604. According to an embodiment, a locating (e.g., tooling) hole 604h is provided around the periphery of the disk clamp 602 hub, but threaded fasteners are not required for sufficient clamping force. Thus, a vertically compact disk clamp 602 is provided, which is effectively and largely recessed or embedded in the corresponding motor hub 604 by the mating threaded feature 602t, 604t, as opposed to a conventional disk clamp that is positioned above the top of the disk stack and requires several fasteners around its periphery for sufficient clamping force. Such a compact disc clamp 602-motor hub 604 arrangement therefore further enables space efficient packaging for stacked, multi-spindle motor, multi-disk pack HDDs. Method for assembling a multi-disk pack hard disk drive

[0025] FIG. 7 is a flow diagram illustrating a method for assembling a multi-disk pack hard disk drive, according to an embodiment. In block 702, a first spindle motor assembly is disposed on a base post extending from a base platform of a base portion. For example, a hollow shaft 302s (FIG. 3A) of the first spindle motor assembly 302 (FIGS. 3A-4) is disposed on and around a base post 306 (FIGS. 3B-4) extending from a base platform 307 (FIGS. 3B-4).

[0026] At block 704, electrical wiring is routed from the first spindle motor assembly along a recess in the base post to an electrical connector coupled to the base. For example, electrical wiring 302w (FIGS. 3A-3B) of the spindle motor assembly 302 is routed along a structural cut-out 306c (FIG. 3B) feature of the base post 306 to an electrical connector 313 (FIGS. 3A-3B, 5B).

[0027] In block 706, a second spindle motor assembly is positioned on top of the first spindle motor assembly that is positioned on the base post. For example, the hollow shaft 304s (FIG. 3A) of the spindle motor assembly 304 (FIGS. 3A-4) is positioned (block 702) on top of the spindle motor assembly 302 already positioned on the base post 306, such that the spindle motor assembly 304 is also positioned on and around the base post 306.

[0028] At block 708, electrical wiring is routed from the second spindle motor assembly along the recess in the base post to an electrical connector coupled to the base portion. For example, electrical wiring 304w of the spindle motor assembly 304 (FIGS. 3A-3B) is routed along the structural cut-out 306c feature of the base post 306 to the electrical connector 313.

[0029] In block 710, a cover is placed over the base, for example, HDD cover 310 (FIG. 4) is placed over the HDD base (see, for example, HDD housing 168 in FIG. 1).

[0030] At block 712, a threaded fastener is fastened through the cover to the base post. For example, the screw 308 (FIGS. 3B-4) is fastened through the HDD cover 310 to the base post 306.

[0031] In general, one approach to improving HDD performance involves the implementation of a multi-actuator system in which multiple independently operating actuators are configured to independently and simultaneously read and / or write from multiple recording disks in a disk pack (or "disk stack"). Dual actuator or split actuator HDDs use dual VCMs (voice coil motors) to improve performance. Additionally, a "split single actuator" configuration contemplates actively using only one actuator at a time. Adding a second spindle motor in the drive and splitting the disks between the motors allows for finer control over the usage and power consumption of each disk pack. That is, the use of a dual spindle motor design such as the multi-disk pack system 300 (FIGS. 3A-4) can address the increasing power issues due to increased activity on the media by using a split actuator design to improve performance. In other words, power consumption can be significantly reduced since a portion of the drive is not being used at any given time, and therefore each set of spindle motors and actuators may be independently controlled to operate in a low power or idle mode, or may be turned off completely to conserve power. Physical Description of Exemplary Operational Contexts

[0032] The embodiments may be used in the context of a digital data storage device (DSD), such as a hard disk drive (HDD). Thus, according to an embodiment, a plan view showing a conventional HDD 100 is shown in FIG. 1 to help describe how a conventional HDD typically operates.

[0033] FIG. 1 shows a functional arrangement of components of a HDD 100, including a slider 110b that includes a magnetic read-write head 110a. Collectively, the slider 110b and the head 110a may be referred to as a head slider. The HDD 100 includes at least one head gimbal assembly (HGA) 110 that includes the head slider, a lead suspension 110c that is typically attached to the head slider via a flexure, and a load beam 110d that is attached to the lead suspension 110c. The HDD 100 also includes at least one recording medium 120 that is rotatably mounted on a spindle 124, and a drive motor (not visible) that is attached to the spindle 124 to rotate the medium 120. The read-write head 110a, which may also be referred to as a transducer, includes a write element and a read element for writing and reading information stored on the medium 120 of the HDD 100, respectively. The medium 120 or multiple disk media may be secured to a spindle 124 with a disk clamp 128 .

[0034] The HDD 100 further includes an arm 132 mounted to the HGA 110, a carriage 134, and a voice coil motor (VCM) including an armature 136 including a voice coil 140 mounted to the carriage 134, and a stator 144 including a voice coil magnet (not shown). The VCM armature 136 is attached to the carriage 134 and is configured to move the arm 132 and HGA 110 to access portions of the media 120, all collectively mounted on a pivot shaft 148 with an intervening pivot bearing assembly 152. In a HDD with multiple disks, the carriage 134 may be referred to as an "E-block" or comb because the carriage is arranged to carry an array of interlocking arms that give the carriage the appearance of a comb.

[0035] An assembly comprising a head gimbal assembly (e.g., HGA 110), including a flexure to which a head slider is coupled, an actuator arm (e.g., arm 132) and / or a load beam to which the flexure is coupled, and an actuator (e.g., VCM) to which the actuator arm is coupled, may be collectively referred to as a head stack assembly (HSA). However, an HSA may include more or less components than those listed. For example, an HSA may refer to an assembly that further includes electrical interconnect components. In general, an HSA is an assembly configured to move a head slider to access portions of the medium 120 for read and write operations.

[0036] With further reference to FIG. 1 , electrical signals including write signals to and read signals from head 110a (e.g., current to the voice coil 140 of the VCM) are transmitted by a flexible cable assembly (FCA) 156 (or “flex cable,” or “flexible printed circuit” (FPC)). The interconnect between flex cable 156 and head 110a may include an arm-electronics (AE) module 160, which may have on-board preamplifiers for the read signal, as well as other read channel and write channel electronics. The AE module 160 may be mounted to the carriage 134 as shown. The flex cable 156 may be coupled to an electrical connector block 164, which in some configurations provides electrical communication through an electrical feedthrough provided by an HDD enclosure 168. The HDD housing 168 (or "enclosure base" or "base plate" or simply "base" or "motor base assembly"), together with the HDD cover, provides a semi-sealed (or, in some configurations, hermetically sealed) protective enclosure for the information storage components of the HDD 100.

[0037] A disk controller including a digital-signal processor (DSP) and other electronic components including servo electronics provide electrical signals to the drive motor, the voice coil 140 of the VCM, and the head 110a of the HGA 110. The electrical signals provided to the drive motor enable the drive motor to rotate providing a torque to the spindle 124, which is then transferred to the medium 120 attached to the spindle 124. As a result, the medium 120 rotates in a direction 172. The rotating medium 120 forms a cushion of air that acts as an air bearing on which the air-bearing surface (ABS) of the slider 110b rides so that the slider 110b flies above the surface of the medium 120 without contacting the thin magnetic recording layer on which the information is recorded. Similarly, in HDDs where a lighter-than-air gas such as helium is utilized as a non-limiting example, the rotating medium 120 creates a cushion of gas that acts as a gas or fluid bearing on which the slider 110b rides.

[0038] An electrical signal provided to the voice coil 140 of the VCM enables the head 110a of the HGA 110 to access the track 176 on which information is to be recorded. Thus, the armature 136 of the VCM swings through an arc 180 to enable the head 110a of the HGA 110 to access various tracks on the medium 120. Information is stored on the medium 120 in a number of radially nested tracks arranged in sectors on the medium 120, such as sector 184. Correspondingly, each track is made up of a number of sectorized track portions (or "track sectors"), such as sectorized track portion 188. Each sectorized track portion 188 may include the recorded information and a header that includes error correction code information and a servo burst signal pattern, such as an ABCD servo burst signal pattern, which is information identifying the track 176. When accessing track 176, a read element of head 110a of HGA 110 reads a servo burst signal pattern that provides a position-error-signal (PES) to the servo electronics, which enables head 110a to follow track 176 by controlling an electrical signal provided to the voice coil 140 of the VCM. Upon locating track 176 and identifying a particular sectored track portion 188, head 110a reads information from track 176 or writes information to track 176 in response to instructions received by a disk controller from an external agent, e.g., a microprocessor of a computer system.

[0039] The electronic architecture of an HDD includes numerous electronic components, such as a hard disk controller ("HDC"), an interface controller, an arm electronics module, a data channel, a motor driver, a servo processor, a buffer memory, etc., each performing its respective function for the operation of the HDD. Two or more of such components may be combined on a single integrated circuit board, referred to as a "system on a chip" ("SOC"). Some, but not all, of such electronic components are typically located on a printed circuit board that is coupled to the bottom side of the HDD, such as in the HDD housing 168.

[0040] References herein to hard disk drives, such as HDD 100 shown and described with reference to FIG. 1, may encompass information storage devices that may be referred to as "hybrid drives." A hybrid drive generally refers to a storage device that has the functionality of both a traditional HDD (see, e.g., HDD 100) combined with a solid-state storage device (SSD) that uses non-volatile memory such as electrically erasable and programmable flash or other solid-state (e.g., integrated circuit) memory. Because the operation, management, and control of different types of storage media are typically different, the solid-state portion of the hybrid drive may include its own corresponding controller functionality, or the controller functionality may be integrated into a single controller along with the HDD functionality. A hybrid drive may be designed and configured to operate and utilize the solid-state portion in several ways, such as by using the solid-state memory as a cache memory, as a non-limiting example, to store frequently accessed data, to store I / O intensive data, and the like. Additionally, a hybrid drive may be designed and configured essentially as two storage devices in a single enclosure, i.e., a traditional HDD and an SSD, with either one or multiple interfaces for host connection. Extensions and Alternatives

[0041] In the foregoing description, the embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. Accordingly, various modifications and changes may be made without departing from the broader spirit and scope of the embodiments. Thus, the sole and exclusive reference of what is, and what the applicants intend to be, the invention is the set of claims originating from this application, in the particular form in which such claims originate, including any subsequent amendments. The definitions expressly set forth herein for the terms contained in such claims shall govern the meaning of the terms as used in the claims. Hence, any limitations, elements, characteristics, features, advantages or attributes not expressly recited in the claims should in no way limit the scope of such claims. Hereby, the specification and drawings are to be regarded in an illustrative and not restrictive sense.

[0042] Additionally, certain process steps may be described herein in a particular order, and alphabetic and alphanumeric symbols may be used to identify particular steps. Unless otherwise specified herein, embodiments are not necessarily limited to any particular order of performing such steps. In particular, symbols are used merely for convenient identification of steps, and are not intended to specify or require a particular order of performing such steps.

Claims

1. A hard disk drive (HDD), a base portion including a base post extending from a base platform; A first spindle motor assembly, A first motor bracket; a first spindle motor assembly including a first disk clamp; a second spindle motor assembly, A second motor bracket; a second spindle motor assembly including a second disk clamp; Equipped with the first spindle motor assembly is mounted on the base post such that the first motor bracket interfaces with the base platform; the second spindle motor assembly is mounted on the base post over the first spindle motor assembly such that the second motor bracket interacts with the first disk clamp; HDD.

2. 10. The HDD of claim 1, wherein each of the first and second spindle motor assemblies includes an axial flux motor.

3. an electrical connector coupled to the base; the first spindle motor assembly further comprising a first electrical trace routed along the base post to the electrical connector; the second spindle motor assembly further comprising a second electrical trace routed along the base post to the electrical connector; The HDD according to claim 1 .

4. 4. The HDD of claim 3, wherein each of the first and second electrical traces is routed within a structural cut-out feature of the base post.

5. each of the first and second spindle motor assemblies further comprising an internal thread on an outer periphery of an annular threaded receiving feature of a respective spindle motor hub; each of the first and second disk clamps includes a circumferential thread on an outer periphery of a clamp hub configured to mechanically mate with a threaded receiving feature of a corresponding spindle motor hub; The HDD according to claim 1 .

6. 2. The HDD of claim 1, wherein the first and second spindle motor assemblies each include a hollow shaft through which the base post is disposed.

7. An upper cover; a screw passing through the top cover and screwed into the base post; The HDD of claim 6 further comprising:

8. a plurality of first disk media rotatably mounted on the first spindle motor assembly; a plurality of second disk media rotatably mounted on the second spindle motor assembly; and Further comprising:

2. The HDD of claim 1, wherein the first spindle motor assembly is configured to rotate the first disk medium independently of the second spindle motor assembly that rotates the second disk medium.

9. a plurality of first disk media rotatably mounted on the first spindle motor assembly; a plurality of second disk media rotatably mounted on the second spindle motor assembly; and a first plurality of head sliders, each housing a read-write transducer configured to read from and write to a respective one of the first disk media; a first actuator configured to move the first plurality of head sliders to access portions of the first disk media; a second plurality of head sliders, each housing a read-write transducer configured to read from and write to a respective one of the second disk media; a second actuator configured to move the second plurality of head sliders to access portions of the second disk media; The HDD of claim 1 further comprising:

10. the first spindle motor assembly is configured to rotate the first disk medium independently of the second spindle motor assembly that rotates the second disk medium; 10. The HDD of claim 9, wherein the first actuator is configured to move the first plurality of head sliders to access portions of the first disk medium independently of the second actuator moving the second plurality of head sliders to access portions of the second disk medium.

11. a plurality of first disk media rotatably mounted on the first spindle motor assembly; a plurality of second disk media rotatably mounted on the second spindle motor assembly; and a plurality of head sliders each housing a read-write transducer configured to read from and write to a respective one of the first and second disk media; a single actuator configured to move the plurality of head sliders to access portions of the first and second disk media; The HDD of claim 1 further comprising:

12. a plurality of first disk media rotatably mounted on the first spindle motor assembly; a plurality of second disk media rotatably mounted on the second spindle motor assembly; and a plurality of head sliders, each housing a read-write transducer configured to read from and write to a respective one of the first and second disk media; an actuator elevator assembly; an actuator attached to the actuator elevator assembly and configured to move the plurality of head sliders to access portions of the first and second disk media; The HDD of claim 1 further comprising:

13. 1. A method of assembling a hard disk drive (HDD), comprising: Positioning a first spindle motor assembly on a base post extending from a base platform of a base portion; positioning a second spindle motor assembly over the first spindle motor assembly disposed on the base post; Positioning a cover over the base; fastening a threaded fastener through the cover and into the base post; The method includes:

14. The method of claim 13 , wherein positioning each of the first and second spindle motor assemblies comprises positioning each spindle motor assembly with an axial flux motor.

15. Routing electrical wiring from the first spindle motor assembly along a recess in the base post to an electrical connector coupled to the base portion; Routing electrical wiring from the second spindle motor assembly along the recess to the electrical connector; The method of claim 13 further comprising:

16. 14. The method of claim 13, wherein positioning each of the first and second spindle motor assemblies includes positioning each spindle motor assembly with a disk clamping hub having circumferential threads on its outer periphery that screw into internal threads of an annular threaded receiving feature of the respective spindle motor hub.

17. The method of claim 13 , wherein positioning each of the first and second spindle motor assemblies includes positioning a hollow shaft over the base post.

18. positioning each of the first and second spindle motor assemblies includes positioning each spindle motor assembly with a plurality of disk media rotatably mounted thereon; 14. The method of claim 13, wherein the first spindle motor assembly is configured to rotate its corresponding disk media independently of the second spindle motor assembly which rotates its corresponding disk media.

19. 1. A multi-actuator hard disk drive (HDD), comprising: a base portion including a base post extending from a base platform; a first spindle motor assembly including a hollow shaft attached to the base post, a first bottom bracket of the first spindle motor assembly interacting with the base platform; a first disk clamp comprising circumferential threads on an outer periphery of a clamp hub configured to mechanically mate with internal threads on an outer periphery of an annular threaded receiving feature of a spindle motor hub of the first spindle motor assembly; a first spindle motor assembly further comprising: a first plurality of disk media attached to the spindle motor hub of the first spindle motor assembly; a second spindle motor assembly including a hollow shaft attached to the base post over the first spindle motor assembly, a second bottom bracket of the second spindle motor assembly interacting with the first disc clamp; a second spindle motor assembly further comprising a second plurality of disk media attached to a spindle motor hub of the second spindle motor assembly; A first actuator system, a first actuator system including first means for moving a first plurality of head sliders to access portions of the first plurality of disk media, each first head slider housing a respective read-write transducer configured to read from and write to at least one disk media of the first plurality of disk media; A second actuator system, a second actuator system including second means for moving a second plurality of head sliders to access portions of the second plurality of disk media, each second head slider housing a respective read-write transducer configured to read from and write to at least one disk media of the second plurality of disk media; A multi-actuator HDD comprising:

20. 20. The multi-actuator HDD of claim 19, wherein each of the first and second spindle motor assemblies comprises an axial flux motor.

21. an electrical connector coupled to the base; the first spindle motor assembly further comprising a first electrical wiring routed within a structural recess in the base post to the electrical connector; 20. The multi-actuator HDD of claim 19, wherein said second spindle motor assembly further comprises a second electrical wiring routed within said structural recess to said electrical connector.

22. 20. The multi-actuator HDD of claim 19, wherein the first spindle motor assembly is configured to rotate the first plurality of disk media independently of the second spindle motor assembly that rotates the second plurality of disk media.

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