Disk drive

Abstract

To provide a disk device capable of suppressing oxygen consumption inside the device and improving reliability.SOLUTION: According to one embodiment, a disk device comprises a housing in which a low-density gas containing oxygen and having a density lower than that of air is sealed, a disk-shaped recording medium rotatably provided in the housing, a spindle motor provided in the housing and supporting and rotating the recording medium, and a magnetic head including a thermal assist element for heating the recording medium. The surface of the magnet of the spindle motor is covered with a shielding film for shielding oxygen permeation.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a disk drive. [Background technology]

[0002] A known disk drive is a magnetic disk drive that has an inert gas such as helium sealed inside its housing. Recently, a magnetic disk drive using a heat-assisted magnetic recording (HAMR) magnetic head has been proposed. HAMR is a technology that increases recording capacity by heating the recording medium with a laser during recording. To ensure the reliability of HAMR, the disk drive must contain at least 3% oxygen, so it is preferable to use helium mixed with oxygen rather than 100% helium as the gas sealed in the housing.

[0003] Generally, components installed inside a disk drive enclosure consume oxygen through chemical reactions. Therefore, to ensure reliability, it is necessary to fill the gas with, for example, 10% or more oxygen. However, increasing the oxygen content increases the gas density, which leads to deterioration in disk drive performance, such as reduced head positioning accuracy and increased power consumption. While coating components with resins such as epoxy to prevent oxidation and corrosion is one way to prevent this, it is difficult to completely cover the surfaces of components, and exposed areas such as pinholes remain. When using oxygen-mixed helium, pinholes will cause oxygen to be consumed through oxidation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 11,270,739 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the embodiments of the present invention is to provide a disk device that can suppress oxygen consumption inside the device and improve reliability. [Means for solving the problem]

[0006] According to an embodiment, the disk device includes a housing filled with a low-density gas containing oxygen and having a density lower than that of air, a disk-shaped recording medium rotatably arranged within the housing, a spindle motor arranged within the housing to support and rotate the recording medium, the spindle motor having a magnet whose surface is covered with a shielding film that blocks oxygen permeation, and a magnetic head including a thermal assist element that heats the recording medium. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an exploded perspective view of a hard disk drive (HDD) according to a first embodiment, showing the top cover exploded. [Figure 2] FIG. 2 is a side view schematically showing the tip of a suspension assembly and a magnetic head in the HDD. [Figure 3] FIG. 3 is a cross-sectional view of a spindle motor portion of the HDD. [Figure 4] FIG. 4 is a diagram showing the results of measuring the oxygen consumption of components of the HDD. [Figure 5] FIG. 5 is an enlarged cross-sectional view of a magnet of the spindle motor. [Figure 6] Figure 6 shows a comparison of the oxygen consumption for each coating film. DETAILED DESCRIPTION OF THE INVENTION

[0008] A disk device and a manufacturing method thereof according to an embodiment will be described below with reference to the drawings. The disclosure is merely an example, and appropriate modifications that are easily conceivable by those skilled in the art while maintaining the gist of the invention are naturally included within the scope of the present invention. Furthermore, the drawings may be schematic in size, shape, etc., of each part compared to the actual embodiment for clarity of explanation, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those previously described with reference to the previous drawings may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0009] (Embodiment) As a disk device, a hard disk drive (HDD) according to an embodiment will be described in detail. FIG. 1 is an exploded perspective view of an HDD according to an embodiment, showing the cover disassembled. As shown in FIG. 1, the HDD includes a substantially rectangular housing 10. The housing 10 includes a rectangular box-shaped base 12 with an open top, an inner cover 14 secured to the base 12 with multiple screws 13 to close the upper opening of the base 12, and an outer cover (top cover) 16 placed on top of the inner cover 14 and welded to the base 12 at its periphery. The base 12 includes a rectangular bottom wall 12a facing the inner cover 14 with a gap therebetween, and side walls 12b extending along the periphery of the bottom wall 12a. The base 12 is integrally molded from, for example, an aluminum alloy. The side walls 12b include a pair of long side walls facing each other and a pair of short side walls facing each other. A substantially rectangular frame-shaped fixing rib 12c protrudes from the upper end surface of the side walls 12b.

[0010] The inner cover 14 is formed, for example, from stainless steel in a rectangular plate shape. The peripheral edge of the inner cover 14 is fastened to the upper surface of the side wall 12b with screws 13, and is fixed inside the fixing rib 12c. The outer cover 16 is formed, for example, from aluminum in a rectangular plate shape. The outer cover 16 is formed with planar dimensions slightly larger than the inner cover 14. The outer cover 16 is airtightly fixed to the base 12 by welding the entire peripheral edge to the fixing rib 12c of the base 12. The airtightly closed housing 10 is filled with a low-density gas with a density lower than that of air, such as helium (He). In this embodiment, the low-density gas contains, for example, approximately 5% oxygen. The oxygen ratio (oxygen concentration) is preferably set in the range of 1% to 10%. Furthermore, the relative humidity inside the housing 10 is adjusted to 3% or less. As an example, by placing a moisture absorbent (desiccant) with excellent moisture absorption properties, such as zeolite, inside the housing 10, it is possible to maintain the relative humidity inside the housing 10 at 3% or less.

[0011] The housing 10 contains a plurality of, for example, ten magnetic disks 18 as disk-shaped recording media, and a spindle motor (SPM) 19 as a drive motor for supporting and rotating the magnetic disks 18. The spindle motor 19 is disposed on the bottom wall 12a. Each magnetic disk 18 is formed in the shape of a disk, for example, 96 mm (3.5 inches) in diameter. Each magnetic disk 18 has a substrate made of a non-magnetic material, for example, glass or aluminum, and magnetic recording layers formed on the upper and lower surfaces of the substrate.

[0012] The magnetic disks 18 are coaxially fitted to a hub (described later) of the spindle motor 19, and are further clamped by a clamp spring 20. As a result, the magnetic disks 18 are supported in a state in which they are positioned parallel to the bottom wall 12a of the base 12. The multiple magnetic disks 18 are rotated at a predetermined rotation speed by the spindle motor 19. The number of magnetic disks 18 mounted is not limited to 10, and may be 9 or less, or 11 or more.

[0013] Within the housing 10 are provided a plurality of magnetic heads 17 that record and reproduce information on the magnetic disks 18, and an actuator assembly 22 that supports these magnetic heads 17 so that they can move freely relative to the magnetic disks 18. Also provided within the housing 10 are a voice coil motor (VCM) 24 that rotates and positions the actuator assembly 22, a ramp load mechanism 25 that holds the magnetic heads 17 in an unload position separated from the magnetic disks 18 when the magnetic heads 17 move to the outermost periphery of the magnetic disks 18, a board unit (FPC unit) 21 on which electronic components such as a conversion connector are mounted, a spoiler 70, and a circulation filter F. The VCM 24 has a pair of yokes and a magnet (not shown) fixed to the yokes.

[0014] The ramp load mechanism 25 includes a ramp 80 attached to the base 12 and a lift tab (described later) provided at the tip of the actuator assembly. The board unit 21 integrally includes a base portion 21a, a narrow strip-shaped relay portion 21b extending from one side edge of the base portion 21a, and a joint portion 21c provided continuous with the tip of the relay portion 21b. The base portion 21a, the relay portion 21b, and the joint portion 21c are formed of a flexible printed circuit board (FPC). The base portion 21a is fixed to the bottom wall 12a. The joint portion 21c is connected to the actuator assembly 22.

[0015] A printed circuit board 41 is screwed to the outer surface of the bottom wall 12a of the base 12. The printed circuit board 41 constitutes a control unit that controls the operation of the spindle motor 19, the operation of the VCM, and the operation of the magnetic head 17.

[0016] 1, the actuator assembly (sometimes referred to as a head stack assembly: HSA) 22 includes an actuator block 29 having a through hole 26, a bearing unit 28 provided in the through hole 26, a plurality of (e.g., eleven) arms 32 extending from the actuator block 29, suspension assemblies (sometimes referred to as a head gimbal assembly: HGA) 30 attached to each arm 32, and a magnetic head 17 supported by the suspension assembly 30. A support shaft (pivot) (not shown) is erected on the bottom wall 12a of the base 12. The actuator block 29 is supported by the bearing unit 28 so as to be rotatable around the support shaft. The actuator assembly 22 has a support frame (not shown) that extends from the actuator block 29 in the opposite direction to the arm 32, and a voice coil that constitutes a part of the VCM 24 is supported by this support frame.

[0017] FIG. 2 is a side view that schematically shows the tip of the suspension assembly 30 and the magnetic head 17. As shown in FIG. 2, the suspension assembly 30 includes a base plate (not shown) attached to the arm 32, a thin, leaf-spring-like load beam 38 extending from the base plate, and a thin, strip-like flexure (wiring member) 42. The flexure 42 has a freely displaceable gimbal portion 44, on which the magnetic head 17 is mounted. A lift tab 40 protrudes from the tip of the load beam 38. The lift tab 40 is engageable with the aforementioned ramp 80, and together with the ramp 80, constitutes the ramp load mechanism 25.

[0018] The load beam 38 has a dimple D that protrudes toward the magnetic head 17 and an opening 51 formed between the dimple D and the lift tab 40. The dimple D abuts against approximately the center of the magnetic head 17 via the gimbal portion 44. This allows the gimbal portion 44 and the magnetic head 17 to swing in the pitch direction and the roll direction around the dimple D.

[0019] The magnetic head 17 has a slider 17a in the shape of a substantially flat rectangular parallelepiped and a head portion 15 provided on the slider 17a. The head portion 15 includes a recording element (write head) 15W and a read element (read head) 15R. The slider 17a has an air bearing surface (ABS) 17b that faces the surface of the magnetic disk 18 and a back surface 17c on the opposite side. The magnetic head 17 is mounted such that the back surface 17c of the slider 17a is placed on a gimbal portion 44 and is fixed to the gimbal portion 44 by, for example, an adhesive.

[0020] The magnetic head 17 constitutes a head of a thermally assisted magnetic recording (HAMA) type. The magnetic head 17 further includes a laser oscillator that functions as a light source, such as a laser diode unit (LDU) 50, a waveguide 52 that guides the laser beam emitted from the LDU 50 toward the magnetic disk 18, and a light emitting element that irradiates the laser beam onto the magnetic disk 18, such as a near-field light generating element 54.

[0021] The LDU 50 is installed on the back surface 17c of the slider 17a and extends in a direction approximately perpendicular to the back surface 17c. The LDU 50 is inserted into an opening 51 of the load beam 38. A waveguide 52 and a near-field light generating element 54 are provided inside the slider 17a. A laser beam generated from the LDU 50 is input to the waveguide 52 and propagates through the waveguide 52 to the near-field light element 73. The near-field light generating element 54 generates near-field light and irradiates it onto the surface of the magnetic disk 18. This locally heats the magnetic recording layer of the magnetic disk 18.

[0022] The read head 15R, write head 15W of the magnetic head 17, and LDU 50 are electrically connected to the control unit of the HDD via the wiring of the flexure 42 and the wiring of the FPC unit 21.

[0023] Next, the configuration of the spindle motor will be described with reference to Figure 3, which is a cross-sectional view of the HDD including the spindle motor 19 portion. 3, in one example, the spindle motor 19 has a pivot 60 standing almost vertically on the bottom wall 12a, a nearly cylindrical hub (rotor) 62 supported so as to be rotatable around the pivot 60, a stator coil CS fixed to the bottom wall 12a and arranged around the hub 62, and a cylindrical magnet M attached to the hub 62 and facing the stator coil CS. The extending end of the pivot 60 is screwed to the inner cover 14 with a fixing bolt 61.

[0024] The hub 62 has an outer peripheral surface positioned coaxially with the pivot 60, and an annular flange 65 formed integrally with the lower end of the outer peripheral surface (the end on the bottom wall 12a side). A cylindrical recess 66 is formed on the bottom side of the hub 62, i.e., on the end on the bottom wall 12a side. The recess (sometimes referred to as a space) 66 opens to the bottom surface of the hub 62. The recess 66 has an inner peripheral surface 66a and an outer peripheral surface 66b positioned coaxially with the pivot 60. The inner peripheral surface 66a and the outer peripheral surface 66b are parallel to each other with a gap between them.

[0025] The stator coil CS is fixed to the bottom wall 12a, and most of it is housed within the recess 66. The stator coil CS is positioned coaxially with the pivot 60 and faces the inner circumferential surface 66a and the outer circumferential surface 66b of the recess 66 with a gap therebetween. The magnet M is disposed within the recess 66 and fixed to the outer peripheral surface 66b of the recess 66. The magnet M is disposed coaxially with the pivot 60 and faces the entire stator coil CS with a gap therebetween. As will be described later, the entire outer surface (front surface) of the magnet M is covered with a shielding film SL.

[0026] The bottom surface of the hub 62 and the flange 65 face the bottom wall 12a with a small gap between them. As a result, a complexly bent or curved passage 68 is formed between the bottom surface of the hub 62 and the flange 65 and the bottom wall 12a. This passage 68 forms a labyrinth seal. The recess 66 in which the magnet M is provided communicates with the internal space of the housing 10 via the passage 68 (labyrinth seal).

[0027] The magnetic disks 18 are engaged with the outer circumferential surface of the hub 62 with the hub 62 inserted through the inner bore. An annular spacer ring 34 is attached to the outer circumferential surface of the hub 62 and sandwiched between two adjacent magnetic disks 18. The magnetic disks 18 and the spacer rings 34 are arranged in order on a flange 65 of the hub 62 and attached to the hub 62 in an alternating stacked state. A disk-shaped clamp spring 20 is attached to the upper end of the hub 62. The clamp spring 20 presses the inner circumferential portions of the magnetic disks 18 and the spacer ring 34 toward the flange 65. This secures the magnetic disks 18 in a stacked state with a predetermined spacing between them. The ten magnetic disks 18 are supported rotatably together with the hub 62 of the spindle motor 19. The ten magnetic disks 18 are supported at a predetermined spacing, parallel to each other and approximately parallel to the bottom wall 12a.

[0028] In the HDD, the VCM 24 rotates the actuator assembly 22 around the support shaft 31, thereby moving the magnetic heads 17 to desired seek positions while facing the surfaces of the magnetic disks 18. During recording operations, each magnetic head 17 performs thermally assisted magnetic recording. When the HDD is not in operation, when the magnetic heads 17 move away from the outer periphery of the magnetic disks 18 and to a predetermined stopping position, the lift tabs 40 of the suspension assemblies 30 ride up onto the guide surfaces of the corresponding ramps 80. As a result, the magnetic heads 17 are held by the ramps 80 in an unload position away from the magnetic disks 18.

[0029] The inventors inspected and analyzed the oxygen consumption (oxygen reduction) of each of the components that make up an HDD. Figure 4 shows the inspection results for the components (Evaluation 1) and the inspection results for the SPM components (Evaluation 2). Evaluation 1 shows the oxygen reduction when the components were left in an environment at 130°C for 72 hours. Evaluation 2 shows the oxygen reduction when the SPM components were left in an environment at 130°C for 40 hours. In FIG. 4, the base motor indicates the base 12 + SPM 19. FIPG indicates the cover gasket. Desiccant indicates the moisture absorbent material.

[0030] As shown in Figure 4, in Evaluation 1, it can be seen that the component "base motor + inner cover + outer cover" had the greatest amount of oxygen loss. In Evaluation 2, it can be seen that, of the components of the SPM, the magnet had the greatest amount of oxygen loss. From the above test results, the inventors have found that, in HDDs, the magnet M of the SPM is the component that consumes the most oxygen. That is, the magnet M is located in the recess 66 of the hub 62, which communicates with the inside of the housing 10 via the passage 68 (labyrinth seal). Therefore, it was found that, although the magnet M is relatively unlikely to come into contact with the air inside the housing 10, it is a component that is prone to consuming oxygen.

[0031] Therefore, in the HDD according to this embodiment, as shown in FIG. 5, the entire surface of the magnet M, which is a component that consumes a large amount of oxygen, is coated with a shielding film SL. In one example of this embodiment, the shielding film SL is formed of a Ni plating layer. The thickness of the shielding film SL is, for example, about 20 to 26 μm. The thicker the shielding film SL, the higher its oxygen blocking ability, so there is no need to set an upper limit to its thickness. The shielding film SL suppresses the absorption and consumption of oxygen by the magnet M, and can suppress a decrease in oxygen within the casing 10.

[0032] In this embodiment, the shielding film refers to a film that blocks the permeation of oxygen. In detail, the shielding film SL has a density of, for example, 2 to 20 g / cm 3 The figure shows a film formed of the material (not including resin). Examples of the shielding film SL that can be used include a metal plating layer, such as Ni plating, a multilayer metal plating layer, such as Ni-Cu-Ni plating, a silicon nitride film, and a diamond-like carbon (DLC) coating film. The density of the resin, e.g., epoxy coating layer is 1.1 to 1.2 g / cm 3In contrast, the density of the Ni plating layer is 8.9 g / cm 3 , the density of DLC is 1.9~3.1g / cm 3 , the density of silicon nitride film (Si-N) is 3.1 g / cm 3 Both have a higher density than resin.

[0033] FIG. 6 is a graph showing a comparison of the oxygen consumption amounts for each coating film. As shown in the figure, the decrease in oxygen concentration was suppressed to a low level for both types of resin-coated Mg and two types of Ni-plated layers with different thicknesses. It can also be seen that the thicker the Ni-plated layer, the more effectively it can suppress the decrease in oxygen concentration.

[0034] As described above, in the HDD according to this embodiment, the entire surface of the magnet M, which consumes a large amount of oxygen, is coated, i.e., covered, with the shielding film SL, which suppresses the absorption and consumption of oxygen by the magnet M and suppresses the reduction of oxygen within the housing 10. This makes it possible to reduce the oxygen content of the helium filled in the housing 10 to, for example, 5%, making it possible to improve the reliability of the HAMR type disk device while maintaining the performance of the disk device. Furthermore, by keeping the relative humidity inside the housing 10 at 3% or less, chemical reactions caused by moisture can be reduced, and oxygen consumption by the components can be further suppressed. As described above, according to this embodiment, it is possible to obtain a disk device that can suppress oxygen consumption inside the device and improve reliability.

[0035] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the above embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. For example, the shielding film of the component is not limited to a Ni plating layer, and various other shielding films can be applied. 3 Various types of films can be selected as long as they are of this type. The thickness of the shielding film is not limited to that in the embodiment and can be changed as appropriate. Furthermore, in addition to the magnet M, the shielding film may also be applied to other components. [Explanation of symbols]

[0036] 10... housing, 12... base, 12a... bottom wall, 12b... side wall, 17... magnetic head, 18...magnetic disk, 19...spindle motor, 22...actuator assembly, 30...Suspension assembly, 64...Hub, 65...Flange, M...Magnet, CS: Stator coil, SL: Shielding film

Claims

1. a housing in which a low-density gas containing oxygen and having a density lower than that of air is sealed; a disk-shaped recording medium rotatably provided within the housing; a spindle motor provided within the housing for supporting and rotating the recording medium, the spindle motor having a magnet whose surface is covered with a shielding film that blocks oxygen permeation; a magnetic head including a thermal assist element for heating the recording medium; A disk device comprising:

2. 2. The disk drive according to claim 1, wherein the shielding film is a diamond-like carbon film.

3. 2. The disk drive according to claim 1, wherein the shielding film is a silicon nitride film.

4. 2. The disk device according to claim 1, wherein the shielding film is formed of a metal plating layer.

5. 5. The disk device according to claim 4, wherein the metal plating layer is a Ni plating layer.

6. 5. The disk device according to claim 4, wherein the metal plating layer is a multi-layer metal plating layer.

7. 2. The disk device according to claim 1, wherein the shielding film has a thickness of 20 to 26 μm or more.

8. 2. The disk drive according to claim 1, wherein the oxygen concentration of the low-density gas is 1% or more and 10% or less.

9. 2. The disk drive according to claim 1, wherein the relative humidity inside the enclosure is 3% or less.

10. the spindle motor includes a pivot shaft provided upright in the housing, a hub rotatably supported on the pivot shaft, a stator coil, and the magnet attached to the hub; 2. The disk drive according to claim 1, wherein the hub has a space in which the magnet is disposed, and the space communicates with a space within the housing via a labyrinth seal defined between the hub and the housing.

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