Glass spacer manufacturing method, glass spacer, and hard disk drive device

Abstract

To provide a manufacturing method for ring-shaped glass spacers provided to contact a magnetic disk in a hard disk drive device, a glass spacer, and a hard disk drive device including the glass spacer.SOLUTION: A method includes forming a film 22 on a surface of a spacer body 20 from which the glass spacer 1 is made.In the process, the film is formed by rotating an outer circumferential end surface 2 of the spacer body and passing through a location where components of the film are in a splayed state.EFFECT: A glass spacer whose entire surface is covered with a conductive film containing tin oxide, zinc oxide, and titanium oxide can be obtained, and in addition, the glass spacer whose thickness of the film on the end surface is thicker than the thickness of the film on the main surface of the spacer can be obtained.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a ring-shaped glass spacer that is provided so as to come into contact with a magnetic disk in a hard disk drive device, a glass spacer, and a hard disk drive device that includes this glass spacer. [Background technology]

[0002] With the recent rise of cloud computing, data centers for cloud computing are using many hard disk drive devices (hereinafter also referred to as HDD devices) to increase storage capacity.

[0003] In HDD devices, ring-shaped spacers are provided between the magnetic disks in the HDD device to keep the magnetic disks spaced apart. These spacers function to prevent the magnetic disks from contacting each other and to precisely space the magnetic disks at predetermined positions. Metal materials, which are inexpensive to manufacture, have traditionally been used as materials for these spacers. However, when a glass substrate is used as a magnetic disk substrate, the spacer and the magnetic disk are in contact with each other, and as the temperature inside the HDD device changes, a difference in thermal expansion occurs between the metal spacer and the glass magnetic disk, causing the magnetic disk to bend, resulting in a deterioration in the flying ability of the magnetic head. A deterioration in the flying ability of the magnetic head is undesirable from the standpoint of reading and writing in a hard disk drive. For this reason, in recent years, the use of glass spacers (hereinafter referred to as glass spacers) has been considered in response to the use of glass substrates as magnetic disk substrates. However, because glass is generally an insulator, static electricity easily accumulates on the magnetic disk or glass spacer due to friction between the rapidly rotating magnetic disk or glass spacer and the air. When the magnetic disk or spacer becomes charged, it becomes more likely to attract foreign matter and fine particles, and the accumulated static electricity can be discharged to the magnetic head, destroying the recording element and reproducing element of the magnetic head, which is undesirable.

[0004] In response to this, a glass spacer is known in which at least the surface of the glass spacer that comes into contact with the magnetic disk and the inner peripheral surface are coated with a conductive ceramic film having a thickness of 0.1 to 3 μm (Patent Document 1). This allows static electricity charged to the magnetic disk to be efficiently released, with almost no wear on the contact surface. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-44969 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when a brittle material such as glass or ceramics is used as the material for the spacer body, even if a conductive coating is formed on the surface of the spacer body, there are cases where some of the brittle material of the spacer body breaks down into fine particles, causing dust to be generated.

[0007] Therefore, the present invention aims to provide a glass spacer that can suppress charging of the magnetic disk and glass spacer in order to suppress the discharge of static electricity from the magnetic head that has become charged to the magnetic disk within the HDD device, and that also suppresses dust generation, a hard disk drive device using this glass spacer, and a method for manufacturing the glass spacer. [Means for solving the problem]

[0008] One aspect of the present invention is a method for manufacturing a ring-shaped glass spacer that is provided so as to contact a magnetic disk in a hard disk drive device. The glass spacer is constructed by forming a film on a glass spacer body. The manufacturing method includes a process of forming the film on a surface of the glass spacer body, In the treatment, the outer peripheral end surface of the glass spacer body is rotated in the circumferential direction, and the outer peripheral end surface is passed through a location where the components of the film are atomized, thereby forming the film.

[0009] It is preferable to rotate the outer peripheral end surface by passing a rotating shaft that fits loosely into a hole in the ring-shaped glass spacer body through the hole, bringing the rotating shaft into contact with a portion of the inner peripheral end surface of the hole, and rotating the rotating shaft.

[0010] The rotating shaft is preferably mounted on a moving mechanism so as to move in one direction while rotating.

[0011] The sprayed area is preferably formed by spraying the film components in mist form from both sides of the conveying path of the glass spacer body.

[0012] Preferably, the treatment includes heating the film formed on the glass spacer body.

[0013] The arithmetic mean roughness Ra of the surface of the film is preferably 1 μm or less.

[0014] The surface resistivity of the film at 22°C is 10 -4 ~10 6 It is preferable that the axial length is [Ω / sq].

[0015] The film includes, for example, any one of tin oxide, zinc oxide, and titanium oxide.

[0016] Another aspect of the present invention is an apparatus for forming a film on the surface of a spacer for a hard disk drive device, which includes a housing having at least a drive motor and a spray nozzle, and incorporating a spacer transport means in which a rotating shaft is stretched across a pair of moving mechanisms.

[0017] Another aspect of the present invention is a ring-shaped glass spacer provided in a hard disk drive device so as to contact a magnetic disk, wherein the entire surface of the glass spacer, including the main surfaces and end faces, is covered with a film containing one of tin oxide, zinc oxide, and titanium oxide, and the thickness of the film at the end faces of the glass spacer is greater than the thickness of the film at the main surfaces of the glass spacer.

[0018] The difference between the maximum and minimum thicknesses of the film on the entire surface of the glass spacer is preferably less than half the maximum thickness.

[0019] The entire surface of the glass spacer is preferably covered with the film having a thickness of less than 100 nm.

[0020] The arithmetic mean roughness Ra of the end faces of the glass spacer is preferably larger than the arithmetic mean roughness Ra of the main surfaces of the glass spacer.

[0021] The surface resistivity of the film at 22°C is 10 -4 ~10 6 It is preferable that the axial length is [Ω / sq].

[0022] Another aspect of the present invention is a hard disk drive device including the glass spacer and the magnetic disk. [Effects of the Invention]

[0023] According to the above-described glass spacer, hard disk drive device, and method for manufacturing a glass spacer, it is possible to suppress charging of the magnetic disk and the glass spacer, and to suppress dust generation. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a perspective view of an appearance of a spacer according to an embodiment. [Figure 2] 1A and 1B are diagrams illustrating the arrangement of a spacer and a magnetic disk according to an embodiment. [Figure 3] 1 is a cross-sectional view of a main part illustrating an example of the structure of an HDD device into which a spacer according to an embodiment is incorporated. [Figure 4] FIG. 2 is a cross-sectional view of an example of a glass spacer according to an embodiment. [Figure 5] 1A to 1C are diagrams illustrating an example of film formation in a glass spacer manufacturing method according to an embodiment. [Figure 6] 3A and 3B are diagrams illustrating an example of a spacer conveying means used in the glass spacer manufacturing method according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] The glass spacer, hard disk drive device, and method for manufacturing the glass spacer of the present invention will be described in detail below. Fig. 1 is an external perspective view of a glass spacer (hereinafter sometimes simply referred to as a spacer) 1 according to one embodiment, and Fig. 2 is a diagram illustrating the arrangement of the spacer 1 and a magnetic disk 5. Fig. 3 is a cross-sectional view of a main part illustrating an example of the structure of an HDD device incorporating the spacer 1. Fig. 4 is a cross-sectional view of an example of the spacer 1.

[0026] The spacer 1 is assembled into the HDD device by stacking the magnetic disks 5 and the spacers 1 alternately, as shown in Fig. 2. As shown in Fig. 3, multiple magnetic disks 5 are fitted onto a spindle 14 that rotates connected to a motor 12 via the spacers 1, and are then secured on top of the spindle 14 with screws via a top clamp 16, so that the disks are attached at predetermined intervals. 2, the spacers 1 and the magnetic disks 5 are alternately arranged so that the spacers 1 are positioned between two magnetic disks 5, maintaining a predetermined distance between adjacent magnetic disks 5. Note that the spacers 1 described in the following embodiments are spacers provided between two magnetic disks 5 so as to be in contact with the magnetic disks 5, but the spacers covered by the present invention also include spacers that are in contact only with the uppermost or lowermost magnetic disk 5. Note that, depending on the specifications of the HDD device, there may be cases where a spacer 1 that is in contact only with the uppermost or lowermost magnetic disk 5 is not provided.

[0027] As shown in FIG. 1, the spacer 1 is ring-shaped and has an outer peripheral end face 2, an inner peripheral end face 3, and two main surfaces 4 that face each other. The inner peripheral end surface 3 is the surface that comes into contact with the spindle 14 and is a wall surface that surrounds a hole whose inner diameter is slightly larger than the outer diameter of the spindle 14 . The dimensions of the annular spacer 1 may be changed as appropriate depending on the specifications of the HDD to be installed. For a nominal 3.5-inch HDD device, the outer diameter is, for example, 30 to 34 mm, the inner diameter is, for example, 24 to 26 mm, the radial width is, for example, 2 to 5 mm, and the thickness is, for example, 0.5 to 3 mm. Furthermore, chamfered surfaces may be provided at the connections between the outer peripheral end face 2 and the inner peripheral end face 3 and the main surface 4. The chamfered surfaces may be linear or arc-shaped in cross section. The dimensions of the chamfered surfaces are, for example, 0.01 to 0.5 mm in width in the radial and thickness directions.

[0028] The main surfaces 4 are two parallel surfaces that contact the magnetic disk 5. The spacer 1 adheres closely to the magnetic disk 5, securing it in place through friction. Because the spacer 1 and the magnetic disk 5 are in contact with each other, differences in thermal expansion between the spacer 1 and the magnetic disk 5 occur as the temperature inside the HDD device changes, causing misalignment and friction. This easily generates static electricity on the insulating glass. Furthermore, friction between the rapidly rotating spacer 1 and the air also easily generates static electricity on the spacer 1. When static electricity builds up on the spacer 1, it easily attracts foreign matter and particles. Furthermore, discharge of the accumulated static electricity to the magnetic head can destroy the recording and reproducing elements of the magnetic head, so static electricity is undesirable. Furthermore, some of the glass may break down into fine particles and generate dust from the surface of the spacer 1. Dust generation is undesirable because the fine particles float within the enclosed space of the HDD device, adhere to the main surface of the magnetic disk 5, and interfere with the magnetic head's ability to read from and write to the magnetic disk 5. Such dust is particularly likely to be generated from the outer peripheral end face of the spacer 1. This is because the outer peripheral end face is constantly exposed during operation of the HDD device and is close to the main surface of the magnetic disk 5. Furthermore, the inner peripheral end face of the spacer 1 may rub against the spacer 1 when the spacer 1 is attached to the spindle, generating dust. This dust is undesirable because it may be transferred to the main surface of the magnetic disk 5 during rework, which is the process of replacing the magnetic disk 5.

[0029] Therefore, to prevent static electricity from accumulating and dust generation, the entire surface of the spacer 1 is covered with a conductive film 22 containing tin oxide or zinc oxide. That is, as shown in FIG. 4, the spacer 1 has a ring-shaped glass spacer body (hereinafter referred to as the spacer body) 20 and a film 22. The film 22 can be, for example, a conductive film containing tin oxide (SnO2) or zinc oxide (ZnO). The film 22 may also be a film containing titanium oxide. Alternatively, the film 22 may be FTO, which is tin oxide doped with fluorine, or AZO, which is zinc oxide doped with aluminum oxide (Al2O3). The thickness of the film 22 covering the entire surface of the spacer 1 is preferably less than 100 nm. Conventionally, deposition techniques include physical vapor deposition (PVD), chemical vapor deposition (CVD), and spraying. However, these deposition methods typically fail to deposit a film on the area where the spacer is in contact with the support member (supporting member) that holds the spacer. This results in a portion of the spacer surface being exposed and unable to deposit a film. This can result in glass fragments forming fine particles and generating dust from the exposed area. To completely eliminate the exposed area, it is possible to remove the spacer from the deposition system while holding it with the support member, and then perform a second deposition while the deposited area is still held by the support member. However, performing two depositions results in approximately double the film thickness unevenness between the area in contact with the support member and the other areas. This also complicates the deposition process and increases costs. In this embodiment, the entire surface of the spacer 1 is covered with a film 22 containing tin oxide, without using the conventional holding member described above.

[0030] The thickness of the film 22 covering the entire surface of the spacer 1 is preferably 200 nm or less, and more preferably less than 100 nm. A thickness exceeding 200 nm may result in excessive manufacturing costs. Furthermore, a thickness of 100 nm or more may result in significant surface irregularities of the film 22, which may cause the convex portions of the film 22 to be pressed when they come into contact with the magnetic disk 5, resulting in some of these convex portions breaking off from the surface of the film 22 and becoming fine particles, which may cause dust generation. This is undesirable because the generated fine particles may be transferred to the main surface of the magnetic disk during rework. Furthermore, the thickness of the film 22 on the outer peripheral end face 2 and the inner peripheral end face 3 of the spacer 1 is preferably thicker than the thickness of the film 22 on the main surface 4 of the spacer 1. Because the film 22 on the outer peripheral end face 2 is exposed to the sealed space of the HDD device, dust generation from the outer peripheral end face 2 must be suppressed. For this reason, the thickness of the film 22 on the outer peripheral end face 2 is made thicker than the thickness of the film 22 on the main surface 4 of the spacer 1 so that the glass of the spacer body 20 is not exposed to the sealed space. On the other hand, the film 22 on the inner peripheral end face 3 is prone to dust generation because it rubs against the spindle 14. For this reason, the thickness of the film 22 on the inner peripheral end face 3 is made thicker than the thickness of the film 22 on the main surface 4 of the spacer 1. For example, the thickness of the film 22 on the main surface 4 of the spacer 1 can be 30 nm or more and 190 nm or less, but 30 nm or more and 90 nm or less is more preferable. The thickness of the film 22 on the outer peripheral end face 2 and the inner peripheral end face 3 can be, for example, 40 nm or more and 200 nm or less, and is more preferably 40 nm or more and less than 100 nm.

[0031] According to one embodiment, the arithmetic mean roughness Ra of the outer peripheral end face 2 and the inner peripheral end face 3 of the spacer 1 is preferably larger than the arithmetic mean roughness Ra of the main surface 4 of the spacer 1. Increasing the arithmetic mean roughness Ra of the outer peripheral end face 2 and the inner peripheral end face 3 of the spacer 1 can improve the adhesion of the film 22. This makes it less likely for the film 22 to peel off due to film stress, even if the film 22 is thicker on the end face than on the main surface. For example, by polishing the main surface 4 of the spacer 1 before forming the film, the arithmetic mean roughness Ra of the main surface 4 of the spacer 1 can be made smaller than that of the outer peripheral end face 2 and the inner peripheral end face 3. The arithmetic mean roughness Ra of the main surface 4 of the spacer 1 is preferably 1.0 μm or less. Furthermore, the arithmetic mean roughness Ra of the outer peripheral end face 2 and the inner peripheral end face 3 of the spacer 1 is preferably 0.5 μm or more. Furthermore, according to one embodiment, the difference between the maximum and minimum film thicknesses of the film 22 on the entire surface of the spacer 1 is preferably less than half of the maximum film thickness. More preferably, this difference is less than one-fourth of the maximum film thickness. If there are no areas on the surface of the spacer 1 where the film 22 is extremely thin due to holding by a holding jig or the like, this difference can be calculated from the film thicknesses on the main surfaces, inner peripheral end face, and outer peripheral end face of the spacer 1. The film thickness on each surface can be, for example, the film thickness at the center of each surface. This reduces the variation in the film thickness of the film 22 on the entire surface of the spacer 1, thereby preventing the film thickness from becoming extremely thin on some parts of the surface when a predetermined film thickness is formed, making it impossible to suppress dust generation.

[0032] The manufacturing of a spacer 1 having such a film 22 includes a process of forming the film 22 on the surface of a ring-shaped spacer body 20, which is the base material of the spacer 1. In this process, the outer peripheral end surface 2 of the spacer body 20 is rotated in the circumferential direction while passing through a location where the components of the film 22 are atomized, thereby forming the film 22. Figure 5 is a diagram illustrating an example of film formation in a manufacturing method of a spacer 1 according to one embodiment. In this way, by rotating the outer peripheral end surface 2 of the spacer body 20 in the circumferential direction and passing through the location where the components of the film 22 are sprayed 23, the film 22 can be formed efficiently and evenly over the entire surface of the spacer body 20. Conventionally, when the outer end surface of the spacer body 20 is held with a holding member, the film 22 is not formed in the held portion. After forming the film 22, it is possible to change the held portion to another location and form the film 22 a second time, but this results in unevenness in the thickness of the film 22. On the other hand, with the film forming method of the present invention, there is no need to change the holding member, and the film 22 can be formed evenly in a single film formation process.

[0033] In one embodiment of a method for forming the film 22, a rotating shaft 50 having a loose fit relative to the inner diameter of the ring-shaped spacer body 20 is passed through the hole, and the rotating shaft 50 is brought into contact with a portion of the inner circumferential surface of the hole (the inner circumferential end surface of the spacer body 20) of the hole. This method rotates the outer circumferential end surface 2 by rotating the rotating shaft 50. Therefore, the surface roughness and material of the rotating shaft 50 can be appropriately designed to generate appropriate friction between the rotating shaft 50 and the inner circumferential end surface of the spacer body 20. Furthermore, the surface of the rotating shaft 50 may be provided with recesses (grooves) or protrusions to prevent axial displacement of the rotating shaft during rotation. Providing recesses or protrusions facilitates increasing the number of ring-shaped spacer bodies attached to a single rotating shaft, thereby improving production efficiency. By rotating the spacer body 20 in the spray state 23, the components of the film 22 can be efficiently adhered to the entire surface of the spacer body 20 (main surface 4, outer peripheral end face 2, and inner peripheral end face 3).

[0034] According to one embodiment, the rotating shaft 50 is preferably mounted on a moving mechanism 52 so as to move in one direction while rotating. By this spacer conveying means, the spacer body 20 can be rotated and conveyed in the spray state 23, while the film 22 can be formed on the entire surface of the spacer body 20. The moving mechanism 52 includes, for example, a pair of spirally wound rotating members 54 and a drive motor (not shown), as shown in Fig. 6. Fig. 6 is a diagram illustrating an example of a spacer conveying means used in the glass spacer manufacturing method of one embodiment. 6 is rotated by the drive motor, the rotary shaft 50 stretched between the rotary members 54 on both sides rotates and moves in the X direction. Therefore, the rotary members 54 are arranged along the transport path of the spacer body 20. According to one embodiment, multiple locations of the spray state 23 are provided, and the spacer body 20 is transported by the moving mechanism 52 and passes through each location of the spray state 23, thereby ensuring that the film 22 is formed over the entire surface of the spacer body 20.

[0035] According to one embodiment, the spray state 23 is preferably formed by spraying the components of the film 22 as a mist from multiple spray nozzles provided around the transport path of the spacer body 20. For example, the multiple spray nozzles can be provided on both sides of the transport path, left and right, above and below, or above and below and left and right. The multiple spray nozzles may also be provided along the transport path of the spacer body 20. By appropriately combining these, it is possible to suppress unevenness in the thickness of the film 22.

[0036] The process of forming the film 22 may include heating the film 22 formed on the spacer body 20 using a heating means during and / or after the formation of the film 22. Alternatively, the spacer body 20 may be heated before the formation of the film 22, and the film 22 may be heated using the residual heat. That is, the film 22 can be heated by an appropriate combination of heating before, during, and after the formation of the film 22. For example, if the film 22 is formed in a liquid state by adhering to the surface of the spacer body 20 in the spray state 23 in which the fine droplets are scattered, the film 22 can be heat-treated to induce a chemical reaction and solidify the film 22. The film 22 is preferably made of a conductive oxide or ceramic. For example, when forming tin oxide as film 22, a liquid spray state 23 is formed by dissolving a tin organic compound such as dibutyltin diacetate or dimethyltin dichloride in a solvent such as ethanol, and film 22 is formed on the surface of spacer body 20 in this spray state 23. Thereafter, the spacer body 20 is heated, for example, at 400 to 600°C to form tin oxide. Note that, as described above, the spraying may be performed after and / or while heating spacer body 20. As the heating means, conventionally known heating devices such as various heaters and heating plates may be used. 6 can be used to form a film on the surface of any spacer, not just glass spacers. Therefore, a film-forming device that incorporates the spacer conveying means shown in FIG. 6 in a housing that is equipped with at least a drive motor, a spray nozzle, and optionally a heating means can form a film on the surface of hard disk drive spacers made of any material.

[0037] The arithmetic mean roughness Ra of the surface of the film 22 is preferably 1 μm or less. The surface resistivity of the film 22 at 22°C is 10 -4 ~10 6 [Ω / sq]. By using such a material, even if the spacer 1 or the magnetic disk 5 becomes charged, the surface resistivity of the spacer 1 is small, so that the charge can flow from the spacer 1 via the spindle 14, or from the magnetic disk 5 via the spacer 1 and the spindle 14, to the outside of the spacer 1 and the magnetic disk 5, thereby suppressing charging of the spacer 1 and the magnetic disk 5. The surface resistivity can be measured, for example, using a four-probe resistivity meter.

[0038] The material of the film 22 is, for example, a tin-containing ceramic containing tin oxide, or a zinc-containing ceramic containing zinc oxide. A material containing titanium oxide may also be used. Furthermore, materials obtained by doping these substances with fluorine or aluminum oxide may also be used. Since the film 22 formed from these materials is conductive, the surface resistivity of the spacer 1 having the film 22 at 22°C can be increased to 10 -4 ~10 6 It can be expressed as [Ω / sq].

[0039] In this way, in the manufacturing method of the spacer 1, the outer peripheral end surface of the spacer body 20 is rotated in the circumferential direction while passing through a location where the components of the film 22 are sprayed 23, thereby forming the film 22. This allows the film 22 to be formed over the entire surface of the spacer body 20, and the film 22 can be formed evenly. In addition, since the entire surface is covered with the film 22, there are no exposed areas of glass, which reduces dust generation. Furthermore, since the process can be performed under atmospheric pressure, the film 22 can be formed at a lower cost than by PVD, CVD, etc.

[0040] The manufacturing method of the spacer 1 described above is not limited to the method of forming the film 22 by rotating the outer peripheral end surface of the spacer body 20 in the circumferential direction and passing it through the location of the spray state 23, and other manufacturing methods can also be used. For example, the film 22 may be formed on the entire surface by placing the spacer body 20 on a table such as a heating plate and spraying multiple times while appropriately changing the way it is placed and the way it is sprayed.

[0041] [Example 1] A glass spacer with an outer diameter of 32 mm, an inner diameter of 25 mm, and a thickness of 2 mm was prepared. The arithmetic mean roughness Ra of the main surface, inner peripheral edge face, and outer peripheral edge face of the glass spacer was 0.3 μm, 0.8 μm, and 0.8 μm, respectively. The film formation device is a rectangular parallelepiped housing (chamber) containing a pair of rotating members (spiral-shaped) equipped with a rotating shaft and a drive motor. Multiple spray nozzles and lamp heaters are installed at regular intervals on the top and bottom surfaces. The spray nozzles and lamp heaters are positioned so that film formation is possible even when the glass spacer is being transported. The glass spacer is passed through a rotating shaft inside the housing, which is then suspended over the pair of rotating members. The lamp heater output is set so that the glass spacer is heated to 400°C. An ethanol solution of dibutyltin diacetate is sprayed every 5 seconds onto a specific area inside the housing, creating a sprayed state within the housing. The drive motor and other conditions are then set so that the glass spacer is transported at a speed of 10 cm / min in the X direction (see Figure 6) and the workpiece rotates at 3 rpm. The rotating shaft then rotates on the rotating members, passing through the sprayed state. In this way, the glass spacer is heated and transported in the sprayed state, forming a film on its surface. The thicknesses of the tin oxide films formed on the main surfaces, inner peripheral end faces, and outer peripheral end faces of the glass spacer were 70 nm, 82 nm, and 90 nm, respectively. Here, the film thickness on the end faces was thicker than the film thickness on the main surfaces. Furthermore, the difference between the maximum and minimum film thicknesses was 20 nm, and the maximum film thickness was 90 nm. Therefore, the difference between the maximum and minimum film thicknesses of film 22 on the entire surface of spacer 1 was less than half and less than one-quarter of the maximum film thickness, indicating very little film thickness variation. Furthermore, the arithmetic mean roughness Ra of these surfaces was 0.3 μm, 0.8 μm, and 0.8 μm, respectively. The surface resistivity of the glass spacer after the tin oxide film formation was 10 at 22°C. -4 ~10 6 [Ω / sq].

[0042] [Example 2] Using glass spacers of the same size as above, the formation of a film on the glass spacer was repeated in the same manner. By reducing the conveying speed in the X direction during spraying, a film thicker than that in Example 1 was formed. The thicknesses of the tin oxide films formed on the main surface, inner peripheral edge face, and outer peripheral edge face of the glass spacer were 140 nm, 170 nm, and 188 nm, respectively. The film thickness on the edge face was thicker than that on the main surface. Furthermore, the difference between the maximum and minimum film thicknesses of the film 22 on the entire surface of the spacer 1 was less than half of the maximum film thickness, indicating minimal film thickness variation. The arithmetic mean roughness Ra of these surfaces was 0.4 μm, 0.9 μm, and 1.0 μm, respectively.

[0043] [Example 3] Using glass spacers of the same size as above, the formation of a film on the glass spacer was repeated in the same manner. By increasing the conveying speed in the X direction during spraying, a film thinner than that of Example 1 was formed. The thicknesses of the tin oxide films formed on the main surface, inner peripheral edge face, and outer peripheral edge face of the glass spacer were 40 nm, 47 nm, and 51 nm, respectively. The film thickness on the edge face was thicker than that on the main surface. Furthermore, the difference between the maximum and minimum film thicknesses of the film 22 over the entire surface of the spacer 1 was less than half and less than one-quarter of the maximum film thickness, indicating very little film thickness variation. The arithmetic mean roughness Ra of these surfaces was 0.3 μm, 0.8 μm, and 0.8 μm, respectively.

[0044] [Reference example] The same glass spacer as in Example 1 was placed on a heating plate and heated to 400°C. While maintaining this temperature, an ethanol solution of dibutyltin diacetate was sprayed from above to a film thickness of 70 nm on the main surface. The glass spacer was then turned upside down and placed on a heating plate. The temperature was then raised to 400°C, and the ethanol solution of dibutyltin diacetate was sprayed on the main surface in the same manner. The thicknesses of the tin oxide films formed on the main surface, inner peripheral edge, and outer peripheral edge of the resulting glass spacer were 70 nm, 140 nm, and 140 nm, respectively. Although the film thickness on the edge was thicker than that on the main surface, the difference between the maximum and minimum film thicknesses did not satisfy the requirement of being less than half of the maximum film thickness. In other words, it was found that the film thickness variation of the film 22 across the entire surface of the spacer 1 was very large. The arithmetic mean roughness Ra of these surfaces was 0.3 μm, 0.9 μm, and 0.9 μm, respectively. [Table 1]

[0045] Two spacers prepared in Example 1 were sandwiched between three magnetic disks (main surface roughness Ra 0.3 nm or less) as shown in Figure 3 to prepare an HDD device, and operation checks such as signal recording and reproduction using a magnetic head were performed, and no particular problems were found. HDD devices were also prepared in the same way using the spacers prepared in Examples 2 and 3 and the Reference Example, and operation checks were performed, and no particular problems were found.

[0046] The glass spacer, hard disk drive device, and method for manufacturing a glass spacer of the present invention have been described in detail above, but the present invention is not limited to the above embodiments, and various improvements and modifications may be made within the scope of the present invention. [Explanation of symbols]

[0047] 1 spacer 2 Outer edge 3 Inner peripheral end face 4 Main surface 5. Magnetic Disk 10. Hard disk drive device 12 motors 14 Spindle 16 Top clamp 20 Spacer body 22 membrane 23 Spray condition 50 Rotating shaft 52 Moving mechanism 54 Rotating member

Claims

1. A ring-shaped glass spacer provided in a hard disk drive device so as to contact a magnetic disk, a film containing any one of tin oxide, zinc oxide, and titanium oxide is formed on each of the main surface, the outer peripheral end face, and the inner peripheral end face of the glass spacer; The glass spacer is characterized in that the thickness of the film at the center of the outer peripheral end face of the glass spacer is thicker than the thickness of the film at the center of the inner peripheral end face of the glass spacer.

2. A glass spacer as described in claim 1, wherein the thickness of the film at the center of the outer peripheral end face or the center of the inner peripheral end face of the glass spacer is thicker than the thickness of the film at the center of the main surface of the glass spacer.

3. A ring-shaped glass spacer provided in contact with a magnetic disk in a hard disk drive device, comprising: a film containing any one of tin oxide, zinc oxide, and titanium oxide is formed on each of the main surface, the outer peripheral end face, and the inner peripheral end face of the glass spacer; a thickness of the film at a center of the outer peripheral end face or a center of the inner peripheral end face of the glass spacer is greater than a thickness of the film at a center of the main surface of the glass spacer;

4. A glass spacer according to any one of claims 1 to 3, wherein the difference between the maximum film thickness and the minimum film thickness of the film at the center of the main surface, the center of the outer peripheral end face, and the center of the inner peripheral end face of the glass spacer is less than half of the maximum film thickness.

5. The glass spacer according to any one of claims 1 to 4, characterized in that the thickness of the film at each of the center of the main surface of the glass spacer, the center of the outer peripheral end face, and the center of the inner peripheral end face is less than 100 nm.

6. 6. The glass spacer according to claim 1, wherein the arithmetic mean roughness Ra of the outer peripheral end face or the inner peripheral end face of the glass spacer is greater than the arithmetic mean roughness Ra of the main surface of the glass spacer.

7. The surface resistivity of the film at 22°C is 10 －４ ~10 ６ The glass spacer according to any one of claims 1 to 6, wherein the glass spacer has a surface roughness of [Ω / sq].

8. 8. A hard disk drive device comprising the glass spacer according to claim 1 and the magnetic disk.

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