JP2001283550A - Magnetic disk drive and component manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove a sulfur component emitted from a rotor hub component and a spacer ring, which are components in a magnetic disk device made of free-cutting stainless steel, to corrode a magnetic head and a magnetic disk. , To prevent obstacles due to deposits. SOLUTION: A rotor hub part 6 of a spindle motor 6 is provided.
b or the spacer ring 7 is formed by cutting from free-cutting stainless steel, and at least a part of the surface of the rotor hub component 6b or the spacer ring 7 on which the magnetic disk 4 is arranged is made of Fe (x) Cr (y 2.) Oxide film 20 which is a mixed layer of O (z) and has a thickness of 20 nm to 500 nm.
Cover with.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive with an outgassing countermeasure and a method for manufacturing parts of the magnetic disk drive.

[0002]

2. Description of the Related Art In a device having a built-in magnetic disk device, for example, a personal computer, when the power is turned on in the morning, the personal computer is used for a long time, and the magnetic disk is in a rotating state during that time. Heat is generated from the spindle motor, which is the driving source, and the heat accumulates over time, so that the temperature inside the airtight container (disk enclosure) of the magnetic disk device becomes considerably high. Due to this temperature rise, a gas called outgas is generated from elements in an airtight container (disk enclosure), for example, an adhesive used for an actuator mechanism such as a spindle motor, a voice coil motor, and a head arm. If it adheres to a device in the (disk enclosure), for example, a component near the magnetic head gap or the surface of the magnetic disk, it causes a malfunction. In order to solve such a problem, a technique of setting an adsorbent for adsorbing outgas in an airtight container (disk enclosure) is disclosed in, for example, JP-A-6-3021.
No. 78 publication. According to this technology,
It is described that a magnetic disk device having high outgas adsorption efficiency can be obtained without requiring a special space.
That is, in order to prevent a decrease in reliability due to outgas inside the magnetic disk device, the outgas is adsorbed and removed by installing various adsorbents inside the magnetic disk device.

[0003] Further, as a device corresponding to the recent miniaturization of a magnetic disk device, an adsorbent composed of carbon, silver, or one or more of fine particles of the same type is attached to the inner wall of a base or a cover of the device. Is characterized in that an adsorbent having a small volume and high absorption efficiency is set.

[0004]

However, in advance,
An HD with an adsorbent attached to the inner wall surface of a magnetic disk drive
A A base plate (base) or HDA top cover is used, but the adsorbent is released to the atmosphere before assembling and enclosing the magnetic disk device. At this time, the gas components in the atmosphere are absorbed and the magnetic disk device is absorbed. When an airtight container (disk enclosure) is formed, there is a problem that the allowable adsorption capacity is reduced. It is difficult to manage to incorporate the adsorbent into the magnetic disk drive while maintaining the performance. Furthermore, if the temperature rises during operation of the magnetic disk drive due to the use of the adsorbent, or if the temperature inside the airtight container (disk enclosure) of the magnetic disk drive rises due to fluctuations in the operating environment temperature, the adsorbent may be used. The adsorbed gas component becomes an outgas and is re-emitted into the magnetic disk device, and there is a problem that the outgas concentration in the magnetic disk device temporarily increases rapidly. Various components inside the magnetic disk drive contain components that cause gas generation (for example, adhesives), and due to heat during operation of the magnetic disk drive, the same gas components are stored inside the magnetic disk drive. , Released as outgas. This outgas has an adverse effect on the interface between the magnetic head and the magnetic disk (magnetic head gap portion), and may further cause a problem of shortening the life of the magnetic disk device such as a spindle motor.

For example, during operation, a magnetic head that slides on a magnetic disk receives a repulsive force due to the pressure of an air flow generated by the rotation of the magnetic disk and flies at a distance of about several nm to perform magnetic recording or reproduction. However, at the same time, it has a structure that stabilizes the floating by generating a suction force. Therefore, the above-mentioned outgas may gradually adhere to or near the air bearing surface (slider surface) of the magnetic head or solidify / precipitate due to various polymerization reactions / decompositions during operation. When the operation time of the magnetic disk device is prolonged, the shape of the air bearing surface (slider surface) of the magnetic head changes due to the above-mentioned outgas deposits, and the flying becomes unstable, and a collision occurs between the magnetic head and the magnetic disk. Malfunction occurs. Alternatively, these solid precipitates may be caught as a relic at the interface between the magnetic head and the magnetic disk during operation of the magnetic disk, and sliding friction may occur. Further, contact start / stop (hereinafter, C
In the case of a magnetic disk device of the SS type, when stopped, the magnetic head comes into contact with an area called a CSS area on the surface of the magnetic disk where user data is not written.
Since the above-mentioned adhesion component of the magnetic head has viscosity at the interface between the magnetic head and the magnetic disk and sticks beyond the rotation torque at the time of starting the spindle motor, a problem called a so-called adsorption phenomenon that the starting cannot be performed may occur. .

As a means for reducing the adhesion of the above-mentioned outgas which affects the reliability of the magnetic disk drive, various kinds of gas adsorbents have been installed in the magnetic disk drive. However, since it is exposed to the air at the time of assembly, it absorbs a large amount of the air. This adsorbent has an adsorption amount limit that cannot adsorb outgas in excess of the saturated adsorption amount, so that the adsorbing ability for outgas generated substantially during operation of the magnetic disk device is greatly reduced. Therefore, it is very difficult to secure the attraction performance satisfying the design specification as the magnetic disk device by such a method. Furthermore, when the temperature inside the airtight container (disk enclosure) of the magnetic disk device becomes high again during the next operation, the outgas component adsorbed by the adsorbent is re-emitted into the airtight container (disk enclosure) of the magnetic disk device. As a result, there has been a problem that the outgas concentration in the airtight container (disk enclosure) of the magnetic disk device temporarily increases and adheres to a magnetic head portion, a magnetic disk, or the like, which adversely affects the operation of the device. Further, in the case of a magnetic disk drive using a magnetic disk having a substrate made of glass as a main material, stainless steel such as SUS430F containing a sulfur compound is used for a rotor hub part and a spacer ring of a spindle motor from the viewpoint of workability. . However, when a stainless steel material such as SUS430F is subjected to a high-temperature and high-humidity environment for a long time, a sulfur compound is decomposed, becomes unstable and easily gasifies, and this gas is used as outgas as an outgas in an airtight container (disk) of a magnetic disk device. Enclosure).

In such a case, in the above-mentioned prior art, the adsorbent cannot completely remove the sulfur gas component in the airtight container (disk enclosure) of the magnetic disk drive.
There is a possibility of causing solid deposition on the surface of an element component such as a magnetic head-magnetic disk, or an obstacle such as corrosion.
Conventionally, the above-mentioned sulfur-containing stainless steel material is subjected to a so-called passivation process for decomposing and removing its sulfur compound by immersing it in a solution of an acid or an alkali at the time of manufacturing the component. In addition, there has been a problem that it is difficult to remove a stable sulfur compound from the viewpoints of solution management and washing spots. In particular, when applied to parts having complicated shapes having various screw holes, such as a rotor hub or a spacer ring of a spindle motor of a magnetic disk drive, the sulfur compound which has become unstable due to the processing remains as a cleaning residue. However, there is a problem that more sulfur is released than the untreated product. In particular, sulfur-based compound gas corrodes the magnetic head element and the surface of the magnetic disk.
It is said that the influence on the long-term reliability of the magnetic disk device is large. On the other hand, in the case of a magnetic disk drive using a glass substrate as the magnetic disk substrate, a free-cutting stainless steel such as SUS430F containing a sulfur compound is used as a rotor hub part of the spindle motor from the viewpoint of thermal expansion coefficient and workability. Therefore, the incorporation of sulfur compounds into the magnetic disk drive is inevitable.

Conventionally, in order to reduce outgas that affects the reliability of the magnetic disk drive, various gas adsorbents have been installed inside the magnetic disk drive. Not only does the adsorption efficiency of the agent itself decrease, but the adsorbed outgas component may be released again. On the other hand, in the case of a magnetic disk drive using a glass substrate as described above, from the viewpoint of workability, the rotor hub parts and spacer rings of the spindle motor use free-cutting stainless steel such as SUS430F containing a sulfur compound. When this material is exposed to a high-temperature and high-humidity environment for a long time, a sulfur compound may be decomposed and gasified.
These sulfur gases may not be completely removed by the adsorbent. The present invention has been made in consideration of the above-described problems, and has as its object to provide a highly reliable magnetic disk device that can efficiently absorb outgas that affects the reliability of the magnetic disk device. . It is another object of the present invention to provide a highly reliable magnetic disk drive by reducing sulfur-based outgas that affects the reliability of the magnetic disk drive. Specifically, after cutting the rotor hub parts and spacer ring of the spindle motor, which is the main source of sulfur-based outgas, by forming a dense oxide film on the surface under high temperature and high humidity environment, the hub material surface An object of the present invention is to provide a highly reliable magnetic disk drive by coating or decomposing and removing a sulfur compound.

[0009]

According to a first aspect of the present invention, there is provided a magnetic disk drive, comprising: a rotor hub rotatably provided on a spindle; and a spindle motor disposed on the rotor hub. At least one magnetic disk rotated by a magnetic disk, a magnetic head for writing / reading data by approaching the surface of the magnetic disk, and an actuator mechanism for seeking, moving, and positioning the magnetic head to a predetermined cylinder position And a magnetic disk drive having a sealed disk enclosure including a base plate to which the spindle motor is fixed, wherein a rotor hub of the spindle motor is made of free-cutting stainless steel, and the magnetic disk of the rotor hub is arranged. At least a part of the surface is composed of Fe (x) Cr (y A mixed layer of O (z), and a thickness is characterized by having an oxide film of 20 nm to 500 nm. According to a second aspect of the present invention, there is provided a magnetic disk drive comprising: a plurality of magnetic disks; and an annular spacer ring disposed between the plurality of magnetic disks. The spacer ring is made of free-cutting stainless steel, and at least a part of its surface is a mixed layer of Fe (x) Cr (y) O (z),
In addition, it has an oxide film having a thickness of 20 nm to 500 nm.

[0010] As described above, the rotor hub, which is a component in the magnetic disk drive made of free-cutting stainless steel,
Since the sulfur component released from the spacer ring is removed before use in the magnetic disk drive, it is possible to prevent the magnetic head and magnetic disk from being corroded by the sulfur, and to prevent the magnetic head from adhering. it can. According to a third aspect of the present invention, there is provided a method for manufacturing a component of a magnetic disk drive, comprising: a rotor hub rotatably provided on a spindle and made of free-cutting stainless steel as a component of the magnetic disk drive. At least one magnetic disk disposed on the rotor hub and rotated by a spindle motor, a magnetic head for writing / reading data by approaching the surface of the magnetic disk, and moving the magnetic head to a predetermined cylinder position What is claimed is: 1. A method for manufacturing a component of a magnetic disk drive, comprising: a disk enclosure having a sealed structure enclosing an actuator mechanism for seeking, moving and positioning and a base plate to which the spindle motor is fixed, wherein at least a part of a rotor hub of the spindle motor is provided. And cutting the rotor hub After cutting processing, it consists a step of heat treatment at a water vapor atmosphere at 0.99 ° C. to 400 ° C..

According to a fourth aspect of the present invention, there is provided a method of manufacturing a component of a magnetic disk drive, the method comprising: arranging a plurality of magnetic disks as magnetic disk device components and a plurality of magnetic disks between the plurality of magnetic disks; A method of manufacturing a component of a magnetic disk drive having an annular spacer ring made of free-cutting stainless steel, wherein at least a part of the spacer ring is cut, and after the spacer ring is cut, And performing a heat treatment in a steam atmosphere at 150 ° C. to 400 ° C. As described above, according to the method of the present invention, the sulfur compound can be vaporized and removed, so that it is possible to cope with a part having a complicated shape as compared with the solution processing, and it is possible to shorten the time for performing the processing.

[0012]

Embodiments of the present invention will be specifically described below with reference to the drawings. (First Embodiment) FIG. 1 is a schematic sectional view of a magnetic disk drive according to a first embodiment of the present invention. The assembly (hereinafter, referred to as a hard disk assembly: HDA) of the magnetic disk device shown in FIG. 1 has an HDA base (base plate) 1a and an HDA top cover 1b, and the HDA base (base plate) 1a and H
The DA top cover 1b forms an airtight container (disk enclosure) of the magnetic disk device. In the airtight container (disk enclosure), an actuator mechanism 2 including a head carriage 2a and a magnetic head 3, a magnetic disk 4 having a plurality of cylinders as a data recording area, the outside of the device and the airtight container of the magnetic disk device (disk Enclosure) and a breathing hole for pressure adjustment, mounted on a spindle 6a, a breathing hole 5 with a particle filter for preventing dust (hereinafter, referred to as particles) from entering the magnetic disk device from outside the device. A spindle motor 6 including a rotor hub 6b, a disk spacer 7 (hereinafter, referred to as a spacer ring), and a disk clamp 8 are stored.

A method for manufacturing the rotor hub 6b and the spacer ring 7 used in the magnetic disk drive of the present embodiment will be described below. First, a 2.5 inch magnetic disk drive rotor hub part 6b is cut into a hub shape from a stainless steel (SUS430F) bar using a lathe, and then a predetermined dimensional accuracy such as waviness of the shaft eccentric rotor hub surface is obtained. Check that is within the default value. After that, in order to form the dense oxide film 20 of the present invention, 150 mm
In a steam atmosphere at 200 ° C., 200 ° C., and 300 ° C., each is maintained for 2 hours. It was also confirmed that it was possible to use a component held in a steam atmosphere at 400 ° C. and 500 ° C. for about 20 minutes. When the dimensional accuracy after the treatment was confirmed, almost no change in the dimensional accuracy due to the treatment was observed. Here, as a comparative material, it was cut in the same manner as above,
Unprocessed product not subjected to a process for forming an oxide film, 60
The dimensional accuracy of the sample subjected to the steam treatment at 0 ° C., 700 ° C., and 800 ° C. for 20 minutes, the treated rotor hub component 6b ′, or the spacer ring 7 ′ was compared and confirmed. These rotor hub parts 6b, 6b 'or spacer rings 7, 7' were first subjected to the same dimensional inspection as before the processing, and the rotor hub 6b subjected to the processing of the present embodiment was obtained.
The samples of the spacer ring 7 and the spacer ring 7 did not show any dimensional change, and all were within the specified dimensions, and were judged to be acceptable products.

On the other hand, the rotor hub part 6b 'and the spacer ring 7' which have been subjected to the steam treatment at 600 ° C., 700 ° C. and 800 ° C. for 20 minutes have the dimensional accuracy, especially the eccentricity, which are all out of the standard. It turned out that it cannot be used as a spacer ring 7 '. (Results of Observation and Analysis of Surface Morphology) The processed surfaces of the rotor hub components 6b and 6b 'or the spacer rings 7 and 7' described above are observed with a scanning electron microscope (hereinafter, referred to as SEM) and analyzed with an X-ray microanalyzer. Was done. First, the processing surfaces of the conventional rotor hub component 6b 'and the spacer ring 7' were observed with a SEM.
It was observed that some sulfur-based precipitates were uniformly dispersed (see FIG. 3). As a result of X-ray microanalyzer analysis of the surface, sulfur was segregated, and it was observed that this precipitate was a sulfur-based intermetallic compound (see FIG. 3). On the other hand, when observing the machining surfaces of the rotor hub component 6b and the spacer ring 7 of the present embodiment, although the circumferential machining marks are observed, the above-mentioned precipitates of about 10 μm are:
Although it became a cavity and it was confirmed that manganese and chromium were slightly segregated, sulfur was hardly detected (see FIG. 2).

(Measurement of Surface Oxide Film Thickness) Further, the state of the oxide film on these processed surfaces was analyzed in the depth direction (thickness) using an Auger electron spectrometer. As a result, the surfaces of the conventional rotor hub part 6b 'and the spacer ring 7'
An oxide film of about 3 nm was detected on the surface in terms of a silicon thermal oxide film (see FIG. 3). On the other hand, in the rotor hub component 6b and the spacer ring 7 of the present embodiment, an iron-chromium-based oxide film having a thickness of 20 to 500 nm was observed, depending on the processing conditions (see FIG. 2). FIG. 2 is a schematic cross-sectional view of the vicinity of the surfaces of the rotor hub component 6b and the spacer ring 7 in the present embodiment. SU, which is stainless steel
In the S430F stainless steel base material 9, a sulfur-based intermetallic compound 10 for improving workability (free-cutting property) is dispersed. In addition, the rotor hub component 6 according to the present embodiment is processed.
A dense oxide film 20 is formed on the surfaces of the spacer b and the spacer ring 7, and the metal sulfide is removed. FIG. 3 shows a rotor hub component 6 made of SUS430F of a conventional process.
FIG. 7 is a schematic cross-sectional view of b ′ and the vicinity of the surface of a spacer ring 7 ′. A sulfur-based intermetallic compound 100 added for the purpose of improving processing is dispersed in a base material 90 of SUS430F, which is stainless steel. Further, a thin natural oxide film 110 of about 5 nm is formed on the surface of these stainless steels.

The compound is also exposed on the surface by processing, is decomposed by moisture (H ₂ O) in the use environment, and becomes unstable sulfur gas 130 in an airtight space (disk enclosure) in the magnetic disk device. It is thought to be released to (Extracted ion component) 50 ml of these rotor hub parts
With ultrapure water, introduced into a polypropylene bag, sealed with a seal, and further sealed with the same bag on the outside,
An extraction experiment of ionic components was performed in hot water at 80 ° C. The extracted water was examined for the content of sulfuric acid ions with an ion chromatograph. As a result, the rotor hub part and the spacer ring per untreated rotor hub part 6b ′ and the spacer ring 7 ′ were compared with each other. 5000 μg / p
Is detected by the rotor hub part 6b and the spacer ring 7 of the present embodiment.
g / piece, almost only ions of the detection limit were detected. (Silver plate discoloration test) Furthermore, these rotor hub parts 6
b, 6b 'and spacer rings 7, 7' together with a silver plate,
As a result of being left for 10 days in a high-temperature and high-humidity environment of 80 ° C. and 90%, the conventional rotor hub part 6 b ′ and the spacer ring 7 ′ were obtained.
In the silver plate contacted with, the contact portion was discolored to brown.

In particular, the area around the screw hole for the disk clamp 8 was significantly discolored and turned black. As a result of analyzing the discolored portion with an X-ray microanalyzer, sulfur was detected in addition to silver. It is presumed that sulfur in the rotor hub part 6b 'and the spacer ring 7' was transferred to form silver sulfide. On the other hand, the rotor hub part 6b and the spacer ring 7 of the embodiment
In the silver plate that was in contact with, a very faint discoloration was confirmed near the screw hole, but no discoloration was observed on the normal contact surface. (Actual machine test) Furthermore, these rotor hub parts 6b, 6
After assembling five magnetic disk devices each as a spindle motor base by combining with magnetic bearings or the like using b ′ and spacer rings 7 and 7 ′, the magnetic disk 4, an actuator structure 2 as a magnetic head stack assembly After performing a servo track write, an operation test such as a predetermined error check was performed. The magnetic disk device was subjected to 60 cycles of a temperature / humidity cycle storage test including dew condensation at 650 ° C. × 80% high temperature and high humidity for 12 hours and 5 ° C. × 8% low temperature and normal humidity for 12 hours. Thereafter, as a result of performing a predetermined read / write check, in the conventional rotor hub part 6b 'and the spacer ring 7' as comparative parts, three out of five units suffered a write-miss problem. In the magnetic disk drive using the rotor hub component 6b and the spacer ring 7, no error occurred.

(Second Embodiment) Next, a second embodiment of the present invention will be described below. The rotor hub parts 6b, 6b 'and the spacer rings 7, 7', which have been processed in the same manner as in the first embodiment, are placed in a high-pressure steam atmosphere furnace for 15 minutes.
The rotor hub component 6b and the spacer ring 7 that have been subjected to a process of holding each at a temperature of 0 ° C., 200 ° C., and 300 ° C. for 20 minutes in a pressurized steam atmosphere of 20 atm are subjected to predetermined cleaning, and then the rotor hub component Using the 6b and the spacer ring 7, five HDDs each were prepared. This HDD
Were subjected to 60 cycles of a temperature / humidity cycle standing test including dew condensation at a high temperature and high humidity of 80 ° C. × 90% for 12 hours and a low temperature of − (minus) 5 ° C. for 12 hours. Thereafter, a predetermined read / write check was performed. As a result, in the conventional rotor hub part 6b 'and the spacer ring 7' as comparative products, 5
Five of the units had write-miss problems, but the rotor hub part 6b and the spacer ring 7 of the same embodiment of the present invention were used.
No error occurred in the HDD using.

[0019]

As described above, according to the present invention, a sulfur-based outgas which affects the reliability of a magnetic disk drive can be reduced, and a highly reliable magnetic disk drive can be provided. Specifically, after processing a rotor hub part or a spacer ring of a spindle motor, which is a main source of sulfur-based outgas, a dense oxide film is formed on the surface thereof in a high-temperature and high-humidity environment, so that the rotor hub part or the spacer ring is formed. By coating or decomposing and removing the sulfur compound on the surface, a highly reliable magnetic disk device can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating one embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the vicinity of a rotor hub component or a spacer ring surface according to an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of the vicinity of a conventional rotor hub component or spacer ring surface.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Disk enclosure 1a ... HDA base plate 1b ... HDA top cover 2 ... Actuator structure 3a ... Head carriage 3 ... Magnetic head 4 ... Magnetic disk 5 ... Breathing hole 6 ... Spindle motor (SPM) 6a Spindle 6b Rotor hub 7 Spacer ring 8 Disk clamp 9 Stainless steel base material 10 Metal sulfide (precipitate) 11 Natural oxide film 20 ... dense oxide film 90 ... stainless steel base material 100 ... metal sulfide (precipitate) 110 ... natural oxide film 130 ... sulfur gas

Claims (4)

[Claims] A rotor hub rotatably provided on a spindle; at least one magnetic disk arranged on the rotor hub and rotated by a spindle motor; A magnetic disk having a sealed disk enclosure including a magnetic head for writing / reading, an actuator mechanism for seeking and moving the magnetic head to a predetermined cylinder position and a base plate on which the spindle motor is fixed. In the apparatus, a rotor hub of the spindle motor is made of free-cutting stainless steel, and at least a part of a surface of the rotor hub on which the magnetic disk is disposed is Fe (x) Cr (y) O.
(Z) a mixed layer having a thickness of 20 nm to 500 nm;
A magnetic disk drive comprising: 2. A magnetic disk comprising: a plurality of magnetic disks; and an annular spacer ring disposed between the plurality of magnetic disks, wherein the spacer ring is made of free-cutting stainless steel, and has at least one of its surfaces. The part is Fe
2. The magnetic disk drive according to claim 1, wherein the magnetic disk drive has a mixed layer of (x) Cr (y) O (z) and a thickness of 20 nm to 500 nm. 3. A magnetic disk drive, comprising: a rotor hub rotatably provided on a spindle and made of free-cutting stainless steel; and at least one magnetic disk disposed on the rotor hub and rotated by a spindle motor. A magnetic head for writing / reading data by approaching the surface of the magnetic disk, an actuator mechanism for seeking and moving the magnetic head to a predetermined cylinder position, and a base plate on which the spindle motor is fixed. A method of manufacturing a component of a magnetic disk drive having a disk enclosure having a sealed structure, comprising: a step of cutting at least a part of a rotor hub of the spindle motor; Step of heat treatment in steam atmosphere at ℃ The method of part production magnetic disk apparatus consisting of. 4. A method of manufacturing a magnetic disk drive component having a plurality of magnetic disks as magnetic disk drive components and an annular spacer ring made of free-cutting stainless steel disposed between the plurality of magnetic disks. A step of cutting at least a part of the spacer ring;
Heat treating in a steam atmosphere at 400 ° C .;