Magnetic disk drive

Abstract

To seal a desiccant in which hygroscopicity is maintained.SOLUTION: According to an embodiment, a magnetic disk device includes a housing in which a base, an inner cover provided with a first through-hole, and an outer cover are combined in this order and airtightly closed, a magnetic disk accommodated in the housing, a first desiccant unit provided in the inner cover so as to be separated from and face the base, and a second desiccant unit provided in the outer cover and inserted into an internal space of the housing via the first through-hole provided in the inner cover so as to be separated from and face the base.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a magnetic disk drive. [Background technology]

[0002] A magnetic disk drive has a housing that houses various components including a magnetic disk. The housing may be, for example, a housing that is made up of a base, an inner cover, and an outer cover, in that order. To reduce the rotational resistance of the magnetic disk, the inside of the housing is filled with He gas or the like.

[0003] In such magnetic disk drives, a desiccant may be enclosed to control humidity inside the housing. In order to maintain the hygroscopicity of the desiccant, it is preferable to limit the exposure of the desiccant to the atmosphere when enclosed inside the housing to a very short period of time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2020 / 0066308 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of one embodiment is to provide a magnetic disk device capable of enclosing a desiccant that maintains hygroscopicity, and a method for manufacturing the magnetic disk device. [Means for solving the problem]

[0006] The magnetic disk device of the embodiment comprises a housing in which a base, an inner cover with a first through hole, and an outer cover are combined in that order to form an airtight seal; a magnetic disk accommodated within the housing; a first desiccant unit provided on the inner cover so as to face the base at a distance; and a second desiccant unit provided on the outer cover and inserted into the internal space of the housing via the first through hole provided in the inner cover so as to face the base at a distance. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an exemplary exploded perspective view of a magnetic disk device according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an example of the configuration of a desiccant assembly according to an embodiment. [Figure 3] FIG. 3 is a schematic diagram showing an example of a procedure for the method for manufacturing the magnetic disk device according to the embodiment. [Figure 4] FIG. 4 is a schematic diagram showing an example of a procedure for a method for manufacturing a magnetic disk device according to an embodiment. [Figure 5] FIG. 5 is a schematic diagram showing an example of the procedure of the method for manufacturing the magnetic disk device according to the embodiment. [Figure 6] FIG. 6 is a schematic diagram showing an example of a procedure for a method for manufacturing a magnetic disk device according to an embodiment. [Figure 7] FIG. 7 is a cross-sectional view taken along the Y direction of a desiccant assembly according to a modified example of the embodiment. [Figure 8] FIG. 8 is a schematic diagram showing an example of a procedure for a method of manufacturing a magnetic disk drive according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments. Furthermore, the components in the following embodiments include those that can be easily imagined by a person skilled in the art or those that are substantially the same.

[0009] [Embodiment] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0010] (Example of magnetic disk device configuration) 1 is an exemplary exploded perspective view of a magnetic disk device 10 according to an embodiment. The magnetic disk device 10 of the embodiment is configured as, for example, an HDD (Hard Disk Drive). However, the magnetic disk device 10 of the embodiment may be another magnetic disk device such as a hybrid HDD.

[0011] In this specification, the X direction, Y direction, and Z direction are defined for convenience. The X direction, Y direction, and Z direction are perpendicular to each other. The X direction is defined as the direction along the width of the magnetic disk device 10. The Y direction is appropriately defined as the direction along the depth of the magnetic disk device 10. The Z direction is defined as the direction along the thickness of the magnetic disk device 10, and may also be referred to as the up-down direction in this specification.

[0012] 1, a magnetic disk device 10 includes multiple magnetic disks 12, a spindle motor 13, multiple magnetic heads 14, a head stack assembly (HSA) 15, a voice coil motor (VCM) 16, a ramp load mechanism 17, a flexible printed circuit board (FPC) 18, a printed circuit board (PCB) 19, and a housing 20 that covers these components. The magnetic heads 14 are also called sliders.

[0013] The housing 20 has a base 21, an inner cover 22, and an outer cover 23. The base 21, the inner cover 22, and the outer cover 23 are made of metal such as aluminum alloy or stainless steel, but the base 21, the inner cover 22, and the outer cover 23 may also be made of other materials.

[0014] The base 21 is a container with a bottom, and has a bottom wall 211 and a side wall 212. The bottom wall 211 is formed in a substantially rectangular plate shape extending along the XY plane. The side wall 212 protrudes in the Z direction from the edge of the bottom wall 211. A plurality of screw holes 213 are formed in the upper surface of the side wall 212.

[0015] The inner cover 22 is formed in a substantially rectangular plate shape extending along the XY plane. The inner cover 22 has a plurality of insertion holes 223 at positions corresponding to the screw holes 213 provided in the side wall 212 of the base 21.

[0016] The inner cover 22 also has a plurality of recesses 221 that are slightly recessed from the top surface of the inner cover 22. These recesses 221 are provided in the inner cover 22 on the inside of the portion that overlaps the side wall 212 of the base 21 in the vertical direction, and a vent hole 222 or an insertion hole 223 that penetrates the inner cover 22 in the plate thickness direction is provided in the center of each of these recesses 221. Screw holes (not shown) are provided in some of the components housed in the base 21. The insertion hole 223 provided in the center of the recess 221 is positioned at a position that corresponds to the screw holes provided in some of these components. Stickers 225 are affixed to the vent holes 222 and the screwed insertion holes 223, respectively, to cover the vent holes 222 and the insertion holes 223.

[0017] Of the ventilation hole 222 or the insertion hole 223 provided in the center of the recess 221, only the ventilation hole 222 is shown in FIG.

[0018] A plurality of screws 224 are inserted into a plurality of insertion holes 223 of the inner cover 22 and fixed to a plurality of screw holes 213 of the base 21, whereby the inner cover 22 is attached to the end of the side wall 212 of the base 21 so as to overlap with the base 21 in the Z direction, and is also fixed to a member housed within the base 21. A gasket (not shown) is interposed between the inner cover 22 and the base 21.

[0019] The outer cover 23 is airtightly joined to the end of the side wall 212 of the base 21 by, for example, welding, so as to cover the inner cover 22.

[0020] This configuration seals the interior of the housing 20. The housing 20 accommodates the above-mentioned magnetic disk 12, spindle motor 13, magnetic head 14, HSA 15, VCM 16, ramp load mechanism 17, and FPC 18. The internal space of the housing 20 is filled with a gas having a density lower than that of air, such as He gas.

[0021] The magnetic disk 12 is, for example, a disk-shaped recording medium having a recording surface with a magnetic recording layer provided on the top surface, bottom surface, etc. In the example of Fig. 1, the diameter of the magnetic disk 12 is, for example, 3.5 inches. However, the magnetic disk 12 is not limited to this example.

[0022] The spindle motor 13 supports and rotates a plurality of magnetic disks 12 stacked at predetermined intervals in the Z direction, in which the recording surfaces of the disks face each other. As described above, the internal space of the housing 20 is filled with, for example, He gas. This prevents the magnetic disks 12 from experiencing air resistance when rotating at high speed, thereby reducing the rotational resistance of the magnetic disks 12.

[0023] The magnetic disk device 10 of the embodiment configured in this manner is also called a He-filled HDD or a He-sealed HDD. By filling the housing 20 with He gas or the like to reduce the rotational resistance of the magnetic disk 12, it becomes possible to configure the magnetic disk 12 thinner, and it becomes easy to increase the number of layers of the magnetic disk 12 and thereby increase the capacity of the magnetic disk device 10.

[0024] The magnetic disks 12 are held on the hub of the spindle motor 13 by, for example, clamp springs. In the example of Fig. 1, the magnetic disk device 10 has ten magnetic disks 12 arranged in the Z direction. However, the number of magnetic disks 12 is not limited to this example.

[0025] The magnetic head 14 records and reproduces information on the recording surface of the magnetic disk 12. In other words, the magnetic head 14 reads and writes information from and to the magnetic disk 12. The magnetic head 14 is mounted on the HSA 15.

[0026] The HSA 15 is rotatably attached to the base 21 at a position spaced apart from the magnetic disk 12 in a direction substantially perpendicular to the Z direction. The VCM 16 rotates the HSA 15 to position the magnetic head 14 at a desired position. The ramp load mechanism 17 holds the magnetic head 14, which has moved to the outermost periphery of the magnetic disk 12, at an unload position spaced apart from the magnetic disk 12.

[0027] The FPC 18 is supported and reinforced by an FPC plate provided on the bottom wall 211 of the base 21. One end of the FPC 18 is connected to a flexure included in the HSA 15. The FPC 18 is electrically connected to the magnetic head 14 via the flexure of the HSA 15. The other end of the FPC 18 is connected to a connector provided on the bottom wall 211 of the base 21.

[0028] The PCB 19 is attached to the outside of the housing 20, such as to the back surface of the bottom wall 211 of the base 21. Various electronic components are mounted on the PCB 19, such as a relay connector that is connected to the connector on the bottom wall 211 of the base 21, an interface (I / F) connector that is connected to a host computer, and a controller that controls the operation of the magnetic disk device 10. The relay connector is electrically connected to the FPC 18 via the connector on the bottom wall 211 of the base 21.

[0029] In a He-filled HDD such as the magnetic disk device 10 of the embodiment, gases other than the filled gas, such as He gas, and moisture can become sources of contamination inside the housing 20, so humidity control inside the housing 20 is important. Therefore, in the magnetic disk device 10 of the embodiment, a desiccant assembly filled with desiccant is enclosed inside the housing 20.

[0030] (Example of desiccant assembly configuration) Next, a configuration example of the desiccant assembly 100 enclosed in the magnetic disk device 10 of the embodiment will be described with reference to FIG.

[0031] Fig. 2 is a schematic diagram showing an example of the configuration of a desiccant assembly 100 according to an embodiment. More specifically, Fig. 2(a) is a cross-sectional view along the Y direction of the desiccant assembly 100 enclosed in the magnetic disk device 10. Fig. 2(b) is a top view showing the internal structure of the magnetic disk device 10 in which the desiccant assembly 100 is enclosed.

[0032] As shown in FIG. 2, the desiccant assembly 100 of the embodiment is provided so as to fit into an empty space in the housing 20, such as an area surrounded by the HSA 15, the VCM 16, and the FPC 18, for example.

[0033] The desiccant assembly 100 is configured to include multiple desiccant units 110, 120. In the example of Fig. 2, these desiccant units 110, 120 are arranged side by side in the Y direction in an area surrounded by the HSA 15, the VCM 16, and the FPC 18. The desiccant unit 120 is located on the side closer to the short side of the inner cover 22 in the Y direction, and the desiccant unit 110 is located on the far side of the inner cover 22 in the Y direction, close to the side where the magnetic disks 12 and the like are housed.

[0034] However, the arrangement of these desiccant units 110, 120 is not limited to the example in Fig. 2. The positions of the desiccant units 110, 120 in the Y direction may be reversed, or the desiccant units 110, 120 may be arranged side by side in a direction other than the Y direction, such as the X direction.

[0035] The desiccant units 110 and 120 of the embodiment are examples of first and second desiccant units, respectively.

[0036] A plurality of through holes 226, 227 are provided in the inner cover 22 so that these desiccant units 110, 120 can be attached, and a through hole 236 is provided in the outer cover 23 at a position that overlaps vertically with the through hole 226 of the inner cover 22. Also, like the above-mentioned vent hole 222 and insertion hole 223 (see FIG. 1) of the inner cover 22, a seal 232 made of, for example, aluminum is affixed to the through hole 236 provided in the outer cover 23, thereby maintaining airtightness inside the housing 20.

[0037] The through holes 226 and 227 provided in the inner cover 22 of the embodiment are examples of the second and first through holes, respectively. The through hole 236 provided in the outer cover 23 is an example of the third through hole.

[0038] The through-hole 226 of the inner cover 22 may be provided separately from the above-mentioned ventilation hole 222, or may be the same as the ventilation hole 222. In this case, the through-hole 226 can also serve as the ventilation hole 222.

[0039] The desiccant unit 110 is attached to the inner surface of the inner cover 22 facing the bottom wall 211 of the base 21 of the housing 20, at a position where the through-hole 226 is provided. The desiccant unit 110 includes a case 111, a filter 112, and a desiccant 113.

[0040] The case 111 is made of resin and includes an internal space that can be filled with a desiccant 113, and has a through-hole 116 on the top surface. The cross section of the case 111 in the direction along the surface of the inner cover 22 can be, for example, circular.

[0041] The upper surface of the case 111 is attached to the inner cover 22 so that the through-hole 116 on the upper surface overlaps the through-hole 226 of the inner cover 22. A filter 112 is provided on the lower surface of the case 111.

[0042] However, case 111 may also be made of metal. In this case, case 111 may be made of the same metal as inner cover 22, such as aluminum alloy or stainless steel, or case 111 and inner cover 22 may be molded integrally. Furthermore, the shape of case 111 is not limited to a circle, and it may have a polygonal cross-sectional shape, such as a rectangle.

[0043] Here, the opening area of ​​the through-hole 226 of the inner cover 22 is formed to be at least smaller than the cross-sectional area of ​​the desiccant unit 110 in the direction along the surface of the inner cover 22. It is more preferable that the through-hole 226 of the inner cover 22 has an opening area that is as small as possible, as long as it is possible to exchange the atmosphere inside the housing 20, which will be described later.

[0044] In addition, the through hole 236 provided in the outer cover 23 can be configured to have an opening area smaller than the cross-sectional area of ​​the desiccant unit 110 in the direction along the surface of the inner cover 22, and can have an opening area approximately equal to that of the through hole 226 of the inner cover 22, for example.

[0045] The filter 112 is, for example, a membrane filter made of PTFE (Poly-Tetra-Fluoro-Ethylene), and is permeable to air, gases such as He, and moisture in gases.

[0046] The desiccant 113 is an adsorbent capable of adsorbing moisture and the like in the gas, and is filled in the internal space of the case 111. The desiccant 113 is exposed to the atmosphere inside the housing 20 via the above-mentioned filter 112. By passing the desiccant 113 through the filter 112 in this manner, dust and the like that may be generated from the desiccant 113 can be removed by the filter 112, and contamination of the inside of the housing 20 is suppressed.

[0047] The desiccant unit 120 is attached to the inner surface of the outer cover 23 facing the surface opposite to the inner surface of the inner cover 22, and is inserted into the internal space of the housing 20 surrounded by the inner cover 22 and the base 21 through a through-hole 227 provided in the inner cover 22. The desiccant unit 120 includes a case 121, a filter 122, and a desiccant 123.

[0048] The case 121 is made of resin and includes an internal space that can be filled with a desiccant 123. The cross section of the case 121 in the direction along the surface of the outer cover 23 can be, for example, circular. The upper surface of the case 121 is attached to the outer cover 23. A filter 122 is provided on the lower surface of the case 121.

[0049] However, case 121 may also be made of metal. In this case, case 121 may be made of the same metal as outer cover 23, such as aluminum alloy or stainless steel, or case 121 and outer cover 23 may be molded integrally. Furthermore, the shape of case 121 is not limited to a circle, and it may have a polygonal cross-sectional shape, such as a rectangle.

[0050] The filter 122 is, like the above-described filter 112, a membrane filter made of, for example, PTFE, and is permeable to air, gases such as He, and moisture in gases.

[0051] The desiccant 123 is an adsorbent capable of adsorbing moisture and the like in the gas, and is filled in the internal space of the case 121. The desiccant 123 is exposed to the atmosphere inside the housing 20 via the above-mentioned filter 122. By passing the desiccant 123 through the filter 122 in this manner, dust and the like that may be generated from the desiccant 123 can be removed by the filter 122, and contamination of the inside of the housing 20 is suppressed.

[0052] Here, adsorbents that adsorb moisture and the like in gases include reversible adsorbents and irreversible adsorbents. Even if a reversible adsorbent's hygroscopicity decreases after adsorbing moisture, it can be restored by subsequent vacuum drying or the like. Irreversible adsorbents cannot restore their hygroscopicity once it has decreased by vacuum drying or the like, and are also difficult to regenerate at temperatures below 80°C, which is the upper limit of the heat resistance of the magnetic disk device 10. On the other hand, irreversible adsorbents can maintain their hygroscopicity even in low-humidity environments of 10% or less, where reversible adsorbents do not function.

[0053] The desiccant 113, 123 may be any combination of a reversible adsorbent and an irreversible adsorbent, i.e., both the desiccant 113, 123 may be an irreversible adsorbent, or one of the desiccant 113, 123 may be a reversible adsorbent and the other an irreversible adsorbent.

[0054] In the magnetic disk drive 10 of the embodiment, for example, it is preferable that the desiccant 113 of the desiccant unit 110 attached to the inner cover 22 is a reversible adsorbent, and the desiccant 123 of the desiccant unit 120 attached to the outer cover 23 is an irreversible adsorbent. More specifically, the desiccant 113 may be made of, for example, silica gel as a reversible adsorbent. The desiccant 123 may be made of, for example, synthetic zeolite such as molecular sieve as an irreversible adsorbent.

[0055] The desiccant units 110, 120 of the embodiment include desiccant units 113, 123, which are examples of first and second desiccant units, respectively. The desiccant units 110, 120 of the embodiment include cases 111, 121, which are examples of first and second cases, respectively, and the case 111 has a through-hole 116 in its upper surface, which is an example of a fourth through-hole.

[0056] (Magnetic Disk Drive Manufacturing Method) Next, a method for manufacturing the magnetic disk device 10 according to the embodiment will be described with reference to Figures 3 to 6. Figures 3 to 6 are schematic diagrams showing an example of the procedure for the method for manufacturing the magnetic disk device 10 according to the embodiment.

[0057] In the manufacturing process of the magnetic disk device 10, first, a plurality of magnetic disks 12, spindle motor 13, magnetic head 14, HSA 15, VCM 16, ramp load mechanism 17, and FPC 18 are assembled in the base 21 so as to be operable as the magnetic disk device 10. In other words, these magnetic disks 12, spindle motor 13, magnetic head 14, HSA 15, VCM 16, ramp load mechanism 17, and FPC 18 are housed in the space within the base 21 so as to be operable.

[0058] After the necessary components have been assembled in the base 21 in this manner, the inner cover 22 is attached to the base 21.

[0059] 3(a), the desiccant unit 110 is attached to the inner surface of the inner cover 22 before it is attached to the base 21. The filter 112 on the underside of the desiccant unit 110 is covered with a seal 118 made of, for example, aluminum, and the through-hole 226 of the inner cover 22 to which the desiccant unit 110 is attached is covered with a seal 228a made of, for example, aluminum from the upper surface side of the inner cover 22, that is, the surface side opposite to the surface facing the base 21. Furthermore, the through-hole 227 of the inner cover 22 is also covered with a seal 228b made of, for example, aluminum from the upper surface side of the inner cover 22.

[0060] As a result, the desiccant 113 in the desiccant unit 110 is isolated from the atmosphere and kept airtight and dry, at least free from moisture, until just before the inner cover 22 is attached to the base 21.

[0061] 3(b), the seal 118 on the underside of the desiccant unit 110 is removed immediately before attachment to the base 21. This causes the desiccant 113 filled in the desiccant unit 110 to start absorbing moisture in the environment in which the desiccant unit 110 is placed.

[0062] As shown in FIG. 4( a ), after removing the seal 118 on the underside of the desiccant unit 110 , the inner cover 22 is quickly attached to the base 21 .

[0063] That is, the inner cover 22 is overlapped with the base 21 with, for example, a gasket or the like (not shown) interposed therebetween, and screws 224 are inserted into the insertion holes 223 of the inner cover 22 and fixed to the screw holes 213 of the base 21. After the screws are fastened, a seal 225 is attached to the insertion holes 223 provided in the recess 221 near the center of the inner cover 22. At this time, the PCB 19 connected to the FPC 18 is also attached to the back surface of the base 21 or the like with these screws 224.

[0064] Also, at this time, with the inner cover 22 attached to the base 21, the lower surface of the case 111 is located above the bottom wall 211 of the base 21 without contacting the bottom wall 211, and a gap is created between the case 111 and the bottom wall 211 of the base 21.

[0065] This allows the desiccant 113 filled in the case 111 to communicate with the space surrounded by the inner cover 22 and the base 21. Therefore, the desiccant 113 in the case 111 is exposed to the atmosphere in the internal space defined by the inner cover 22 and the base 21 via the filter 112.

[0066] The internal space defined by the inner cover 22 and the base 21 is initially filled with air containing moisture, etc. After the inner cover 22 is screwed to the base 21, the air inside the inner cover 22 and the base 21 is sucked through the ventilation holes 222 provided in the inner cover 22. Furthermore, a gas with a lower density than air, such as He gas, is filled into the inner cover 22 and the base 21 through the ventilation holes 222.

[0067] At this time, the seal 228a covering the through-hole 226 of the inner cover 22 may be temporarily removed, and the air inside the inner cover 22 and the base 21 may be sucked through the through-hole 226 as well as through the above-mentioned vent hole 222, and He gas or the like may be filled into the inner cover 22 and the base 21. Alternatively, if the through-hole 226 and the vent hole 222 are the same as each other as described above, the atmosphere inside the inner cover 22 and the base 21 may be replaced solely by using the through-hole 226.

[0068] The above-described air evacuation and filling with He gas or the like are carried out promptly after the inner cover 22 and the base 21 are assembled. This allows the progress of moisture adsorption in the air, which begins with the desiccant 113 after the seal 118 is removed, to be limited to a short time, thereby preventing a decrease in the moisture absorption performance of the desiccant 113.

[0069] In this way, the inner cover 22 is airtightly attached to the base 21. After the inner cover 22 is attached to the base 21, operation tests and the like are performed on the various components assembled inside the base 21. Thereafter, the outer cover 23 is attached to the inner cover 22 and the base 21.

[0070] 4(b), a desiccant unit 120 is attached to the inner surface of the outer cover 23 before it is attached to the base 21 and the inner cover 22. The filter 122 on the lower surface of the desiccant unit 120 is covered with a seal 128 made of, for example, aluminum.

[0071] As a result, the desiccant 123 in the desiccant unit 120 is isolated from the atmosphere and kept airtight and dry, at least free from moisture, until just before the outer cover 23 is attached to the base 21 and inner cover 22.

[0072] 5(a), the seal 128 on the underside of the desiccant unit 120 is removed immediately before attachment to the base 21 and the inner cover 22. This causes the desiccant 123 filled in the desiccant unit 120 to start absorbing moisture in the environment in which the desiccant unit 120 is placed.

[0073] Additionally, the seals 228a and 228b that respectively close the through-holes 226 and 227 are removed from the upper surface of the inner cover 22. As a result, the internal spaces of the inner cover 22 and the base 21 are again in communication with the outside air via the through-holes 226 and 227, and the desiccant 113 of the desiccant unit 110 is exposed to the atmosphere via the through-hole 226.

[0074] FIG. 5(b) is a top view of the inner cover 22 after the seals 228a and 228b have been removed.

[0075] 5(a) and 5(b), by removing the seals 228a and 228b, the through-hole 226 of the inner cover 22 reopens to a position where it overlaps vertically with the through-hole 236 of the outer cover 23. Also, the through-hole 227 of the inner cover 22 reopens to a position where it overlaps vertically with the desiccant unit 120 attached to the inner surface of the outer cover 23.

[0076] Here, the opening area of ​​the through-hole 227 of the inner cover 22 is formed larger than the cross-sectional area of ​​the desiccant unit 120 in the direction along the surface of the outer cover 23. This allows the desiccant unit 120 attached to the outer cover 23 to be inserted into the housing 20 through the through-hole 227 of the inner cover 22.

[0077] As shown in FIG. 6, after the seals 228a, 228b, and 128 are removed, the outer cover 23 is placed on the inner cover 22, and the outer cover 23 is welded to the end of the side wall 212 of the base 21.

[0078] After the outer cover 23 is welded to the base 21, air is sucked from inside the housing 20 through the through-holes 236 provided in the outer cover 23 and the through-holes 226 provided in the inner cover 22. He gas, etc., is filled into the housing 20 through these through-holes 236, 226. At this time, the He gas, etc., flows into the housing 20 from the through-hole 116 on the top surface of the case 111, via the desiccant 113 and the filter 112 inside the case 111. Therefore, the housing 20 can be filled with clean He gas, etc., from which dust, etc., has been removed, in a drier state.

[0079] Thereafter, a seal 232 is affixed to the upper surface of the outer cover 23 to airtightly cover the through-hole 236. In this manner, the through-holes 226, 236 of the inner cover 22 can be opened multiple times until the outer cover 23 is assembled to the inner cover 22 and the base 21 and the interior of the housing 20 is finally airtightly sealed. Therefore, as described above, by making these through-holes 226, 236 as small as possible, it becomes difficult for outside air to flow into the interior of the housing 20 during the manufacturing process of the magnetic disk drive 10, and it becomes easier to keep the interior of the housing 20 dry.

[0080] In this manner, the magnetic disk device 10 of the embodiment is manufactured.

[0081] If at least one of the desiccant 113, 123 in the desiccant unit 110, 120 is a reversible adsorbent or the like, a process for restoring the hygroscopicity of the desiccant 113, 123 may be performed at a predetermined timing after the outer cover 23 is attached to the inner cover 22 and the base 21. To restore the hygroscopicity of the desiccant 113, 123, a heat drying process or the like can be performed in a vacuum.

[0082] Here, the time from when the seal 118 and the like is removed to when the outer cover 23 is attached to the desiccant 113 of the desiccant unit 110 to when the inside of the housing 20 is finally airtightly sealed is longer than the time from when the seal 128 of the desiccant 123 of the desiccant unit 120 is removed. For this reason, as described above, it is more preferable that the desiccant 113 of the desiccant unit 110 be a reversible adsorbent, for example, so that the moisture absorption properties of the desiccant 113 can be restored.

[0083] Furthermore, by using an irreversible adsorbent for the desiccant 123 of the desiccant unit 120, from which the seal 128 is removed immediately before the outer cover 23 is attached, which has difficulty in recovering its reduced moisture absorption properties even in low humidity environments, as described above, it is possible to more precisely control the humidity inside the housing 20 after it has been finally hermetically sealed.

[0084] (Overview) In recent years, gas-sealed HDDs, in which helium gas or other gases are sealed inside the housing, have become the mainstream for large-capacity magnetic disk drives. For helium-sealed HDDs, humidity control inside the housing is an important issue in order to improve the reliability of the magnetic disk drive. Humidity can have a particularly pronounced effect on HDDs that use heat-assisted magnetic recording (HAMR), which writes information using heat assistance.

[0085] Therefore, in He sealed HDDs, humidity inside the housing is controlled by sealing in a desiccant, for example. If the desiccant is exposed to the atmosphere for a long period of time during the assembly process of the magnetic disk drive, there is a concern that the desiccant may be sealed in with reduced moisture absorption performance or may become saturated before the housing is sealed.

[0086] According to the embodiment of the magnetic disk device 10, the device is provided with a desiccant unit 110 provided on the inner cover 22 so as to face the base 21 at a distance, and a desiccant unit 120 provided on the outer cover 23 and inserted into the internal space of the housing 20 through a through hole 227 provided in the inner cover 22 so as to face the base 21 at a distance.

[0087] As a result, moisture absorption by the desiccant units 110, 120 begins at different times, that is, when the inner cover 22 is assembled to the base 21 and when the outer cover 23 is assembled to the base 21. As a result, from an overall perspective, the desiccant 113, 123 is prevented from reaching a saturated state, and the desiccant 113, 123 can function for a longer period of time.

[0088] According to the magnetic disk device 10 of the embodiment, the inner cover 22 has a through-hole 226 at a position that overlaps vertically with the desiccant unit 110. The outer cover 23 has a through-hole 236 at a position that overlaps vertically with the through-hole 226 of the inner cover 22. The desiccant unit 110 has a case 111 that is filled with desiccant 113 and has a through-hole 116 provided at a position that overlaps vertically with the through-hole 226 of the inner cover 22.

[0089] This allows the atmosphere inside the housing 20 to be replaced again after the inner cover 22 and the outer cover 23 are attached to the base 21. This makes it possible to make the atmosphere inside the housing 20 cleaner and lower in humidity.

[0090] According to the magnetic disk device 10 of the embodiment, the outer cover 23 is provided with a seal 232 that covers the through-hole 236 from the side opposite to the side facing the inner cover 22. This makes it possible to maintain airtightness inside the housing 20.

[0091] According to the magnetic disk device 10 of the embodiment, the opening area of ​​the through-hole 226 of the inner cover 22 is smaller than the cross-sectional area in the direction along the surface of the inner cover 22 of the desiccant unit 110. In this way, by forming the through-hole 226 of the inner cover 22 to be sufficiently small, it is possible to prevent outside air from flowing into the housing 20 through the through-hole 226 during the manufacturing process of the magnetic disk device 10, thereby preventing the humidity inside the housing 20 from increasing.

[0092] According to the magnetic disk device 10 of the embodiment, the desiccant 113 is a reversible adsorbent that can recover its hygroscopicity by drying, or an irreversible adsorbent that retains hygroscopicity even in a lower humidity environment than a reversible adsorbent, and the desiccant 123 is an irreversible adsorbent. In this way, by using an irreversible adsorbent with high hygroscopicity for at least one of the desiccant 113 and the desiccant 123, it is possible to more precisely control the humidity inside the housing 20.

[0093] According to the magnetic disk device 10 of the embodiment, the desiccant 113 is a reversible adsorbent that can restore its hygroscopicity by drying, and the desiccant 123 is an irreversible adsorbent that retains hygroscopicity even in environments with lower humidity than the reversible adsorbent.

[0094] In this way, by using a reversible adsorbent for the desiccant 113, which starts absorbing moisture early during the manufacturing process of the magnetic disk device 10, it becomes possible to restore the moisture absorption properties of the desiccant 113 once again in the final stage of the manufacturing process. Furthermore, by using an irreversible adsorbent for the desiccant 123, which starts absorbing moisture late during the manufacturing process of the magnetic disk device 10, it is possible to suppress saturation of the desiccant 123 even if it is difficult to restore the moisture absorption properties, and the desiccant 123 with higher moisture absorption performance can maintain low humidity inside the housing 20 for a long period of time.

[0095] (Variation) Next, a desiccant assembly 100a according to a modified example of the embodiment will be described with reference to Figures 7 and 8. The desiccant assembly 100a according to the modified example differs from the above-described embodiment in that a gasket 233 is provided.

[0096] 7 is a cross-sectional view of a desiccant assembly 100a according to a modified example of the embodiment taken along the Y direction. In the following drawings, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof may be omitted.

[0097] As shown in FIG. 7, a desiccant assembly 100a of the modified example includes the components of the desiccant assembly 100 of the above-described embodiment, and an outer cover 23a has a gasket 233 around the desiccant unit 120.

[0098] The gasket 233 is provided at the attachment portion of the desiccant unit 120 to the outer cover 23a so as to surround the desiccant unit 120. As described in the manufacturing method of the magnetic disk drive 10 of the above embodiment, the inner cover 22 is attached to the base 21 via, for example, a gasket. As with the gasket interposed between the inner cover 22 and the base 21 described above, for example, a resin gasket can be used as the gasket 233 of the desiccant assembly 100a of the modified example.

[0099] However, the material of the gasket 233 is not limited to resin, and the gasket 233 may be made of, for example, a metal that has sufficient flexibility.

[0100] As described above, the inner cover 22 is provided with a through-hole 227 so that the desiccant unit 120 attached to the outer cover 23a can be inserted into the internal space of the housing 20. In the desiccant assembly 100a of the modified example, a gasket 233 provided around the desiccant unit 120 seals the gap that occurs between the desiccant unit 120 and the inner cover 22 via the through-hole 227.

[0101] This shields the space between the outer cover 23a and the inner cover 22 from the internal space of the housing 20, which is surrounded by the inner cover 22 and the base 21. For example, even if gas or the like is generated in the space between the outer cover 23a and the inner cover 22, the through-hole 227 of the inner cover 22 prevents the gas or the like from flowing directly into the internal space of the housing 20 through the gap created around the desiccant unit 120.

[0102] The space between the outer cover 23a and the inner cover 22 is also connected via the through-hole 226 in the inner cover 22, but gases and other substances flowing into the housing 20 from the through-hole 226 reach the inside of the housing 20 via the desiccant unit 110, so moisture and other substances in the gas can be removed in advance.

[0103] 8 is a schematic diagram showing an example of a procedure for a method for manufacturing a magnetic disk drive according to a modified embodiment. More specifically, FIG. 8 shows steps corresponding to the steps in FIG. 5 of the above-described embodiment.

[0104] As shown in FIG. 8(a), the seal 128 on the lower surface of the desiccant unit 120 and the seals 228a and 228b that close the through holes 226 and 227 on the upper surface of the inner cover 22 are removed immediately before attachment to the base 21 and the inner cover 22.

[0105] Furthermore, the outer cover 23a of the modified example is further provided with a gasket 233 around the desiccant unit 120 attached to the inner surface of the outer cover 23a.

[0106] As shown in FIG. 8(b), when the cross-sectional shape of the desiccant unit 120 along the outer cover 23a is circular or the like, the gasket 233 has an annular shape that follows the circular shape of the desiccant unit 120.

[0107] By overlapping such outer cover 23a on inner cover 22 and welding it to base 21, desiccant unit 120 on the inner surface of outer cover 23a is inserted into a position facing base 21 inside housing 20 via through-hole 227 of inner cover 22. At this time, gasket 233 around desiccant unit 120 is pressed against the edge of through-hole 227 of inner cover 22 and crushed, filling the gap between desiccant unit 120 and inner cover 22 caused by through-hole 227.

[0108] In the magnetic disk device of the modified example, a gasket 233 is disposed around the desiccant unit 120 to seal the gap that forms between the desiccant unit 120 and the inner cover 22 due to the through-hole 227 in the inner cover 22. This prevents the space between the inner cover 22 and the outer cover 23a from directly communicating with the internal space of the housing 20 surrounded by the inner cover 22 and the base 21. This allows for more precise humidity control of the internal space of the housing 20 and also prevents dust and other particles from entering the internal space of the housing 20.

[0109] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0110] 10...magnetic disk device, 12...magnetic disk, 20...casing, 21...base, 22...inner cover, 23, 23a...outer cover, 100, 100a...desiccant assembly, 110, 120...desiccant unit, 113, 123...desiccant, 116, 226, 227, 236...through hole, 118, 128, 228a, 228b, 232...seal.

Claims

1. a housing in which a base, an inner cover provided with a first through hole, and an outer cover are combined in this order to form an airtight closed housing; a magnetic disk housed in the housing; a first desiccant unit provided on the inner cover so as to face the base at a distance from the base; a second desiccant unit provided on the outer cover and inserted into the internal space of the housing through the first through-hole provided in the inner cover so as to face the base at a distance from the base, Magnetic disk device.

2. The inner cover is a second through-hole at a position overlapping the first desiccant unit in the vertical direction; The outer cover is a third through hole at a position vertically overlapping with the second through hole; The first desiccant unit comprises: a first case filled with a first desiccant and having a fourth through hole provided at a position overlapping the second through hole in the vertical direction; The outer cover has: a seal is attached to cover the third through-hole from the surface opposite to the surface facing the inner cover; 2. The magnetic disk drive according to claim 1.

3. The opening area of ​​the first through hole is a cross-sectional area of ​​the first desiccant unit in a direction along the surface of the inner cover; 3. The magnetic disk drive according to claim 2.

4. a gasket is interposed around the second desiccant unit to seal a gap formed between the second desiccant unit and the inner cover by the first through-hole; 2. The magnetic disk drive according to claim 1.

5. the first desiccant unit has a first case filled with a first desiccant; the second desiccant unit has a second case filled with a second desiccant; The first desiccant is a reversible adsorbent capable of recovering its hygroscopicity by drying, or an irreversible adsorbent that retains hygroscopicity even in an environment with lower humidity than the reversible adsorbent, The second desiccant is It is an irreversible adsorbent, 2. The magnetic disk drive according to claim 1.

6. the first desiccant unit has a first case filled with a first desiccant; the second desiccant unit has a second case filled with a second desiccant; The first desiccant is It is a reversible adsorbent that can recover its hygroscopicity by drying. The second desiccant is An irreversible adsorbent that has hygroscopicity even in an environment with lower humidity than the reversible adsorbent, 2. The magnetic disk drive according to claim 1.

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