JP2001338481A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique of lessening the gas contamination within a magnetic disk device more efficiently than heretofore in order to improve the reliability of the magnetic disk device which is made lower in flying height as a head slider and a disk increasingly come into intermittent contact with each other and which is required to operate under a high-temperature environment or for a long time. SOLUTION: A highly adsorptive thin film consisting of carbon (C) or material of any among the carbon (C), TiO2, SnO2 and Fe2O3 including >=1 kind of other elements is formed on the inner wall of a magnetic disk casing. Further, the inner wall of the casing is formed not as a plane but to a shape having fine ruggedness or a mechanism for cooling the casing from the outside is added thereto.

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, and more particularly, to a magnetic disk drive having durability in a high temperature environment such as a vehicle.

[0002]

2. Description of the Related Art A magnetic disk device used as an external storage device of a computer system includes a magnetic disk for recording information, a magnetic head for recording / reproducing information on / from the magnetic disk, and components for supporting and driving these components. It is mounted, covered with a housing cover, and housed.

FIG. 2 is a schematic view of a cross section of a magnetic disk drive. The magnetic disk 4 is rotated by the spindle motor 3, and a head slider 9 mounted with a head flies above the magnetic disk 4 by air pressure generated by the rotation. The head slider 9 is fixed to the tip of the head slider support 2. The head slider 9 can be moved on the magnetic disk 4 in the radial direction by driving the head slider supporting portion 2 by the driving portion 1,
Recording and reproduction of information are performed at an arbitrary position on the magnetic disk 4.

A magnetic disk, a magnetic head, and components for supporting and driving them are mounted on a housing base 12 and covered by a housing cover 11.

[0005] With the dramatic increase in recording density, the flying height of the head slider with respect to the magnetic recording medium in the magnetic disk device must be significantly reduced as compared with the conventional device. As a result, the head slider and the magnetic disk intermittently come into contact with each other, which causes problems such as unstable flying and head crash after a long period of operation. Flying instability is a phenomenon in which the flying height of the head slider fluctuates.
This causes a problem that recording and reproduction of a magnetic signal cannot be performed. A head crash is a failure in which a magnetic disk or a magnetic head as a recording medium is damaged by contact of the head.

It is considered that such an obstacle is accelerated by gas contamination in the atmosphere in the magnetic disk drive. For example, it is considered that the organic silicone contained in the adhesive or the release agent used for the device member is oxidized by contact between the head and the disk to form a solid silicon oxide, which causes a head crash. Further, even if a head crash does not occur, a deposit considered to be caused by contamination occurs on a pad surface of a head slider air bearing surface (hereinafter, abbreviated as ABS), and a substantial flying height increases the read / write. An error occurs.

As a method of removing gas contamination which is considered to be a cause of such a trouble, a conventional method of removing adsorbent 10 such as activated carbon into a disk device as disclosed in Japanese Patent Application Laid-Open No. Sho 60-219695 is known. Have been installed, and measures have been taken to adsorb and remove gas contamination. Alternatively, Japanese Patent Application Laid-Open No. 6-76556 discloses a method in which an organic polymerization catalyst is provided in a housing to polymerize and remove an organic gas. Further, Japanese Unexamined Patent Application Publication No.
As disclosed in Japanese Patent Publication No. 75-75, measures have been proposed for attaching a fiber sheet for adsorbing gas generated in the housing inside the housing.

However, in recent years, magnetic disk devices have been required to ensure durability in a high-temperature environment such as in-vehicle use and reliability for a longer period, and conventional measures have become insufficient. Was. That is, since the amount of generated gas contamination increases as the temperature rises or elapses with time, a method for removing gas contamination that is more efficient than before has been required. In particular, in the conventional countermeasures, it is important to remove pollutant gas which is likely to cause contamination by adsorbing to a magnetic head or a magnetic disk before the adsorption and removal.

[0009]

As the recording density is improved, the flying height of a magnetic disk device is reduced as the head slider and the disk are intermittently contacted with each other. It is required to run. An object of the present invention is to provide a technique for responding to such a demand to reduce the gas contamination in a magnetic disk drive more efficiently than before, and to improve the reliability of the magnetic disk drive.

[0010]

Means for Solving the Problems In the case of low-molecular components or components having no adsorptive functional group among gas contaminants generated in the magnetic disk device, the adsorption energy is small, so that the surface of the components and the surface of the magnetic disk are hardly adsorbed. As the adsorption and desorption to these surfaces is repeated without staying for a long time, the particles finally reach the inside of the adsorbent 10 shown in FIG. 2, for example, activated carbon, are adsorbed, and are trapped for a long time.

However, on the other hand, gas contaminants having a large molecular weight or gas contaminants having an adsorptive functional group, once adsorbed on a certain surface, reach an adsorbent and are adsorbed.
Before being trapped, it is attracted to the head slider or the surface of the magnetic disk, contaminating them and increasing the possibility of causing a failure between the magnetic head and the magnetic disk.

In order to remove such contaminants having a large adsorption energy, the area ratio of the coated portion in the apparatus is simply higher than that of the adsorbent having a large surface area including the internal fine pores but a small external area. It is considered that an adsorption film having a larger value is more effective. Therefore, an adsorbent having a substantially large surface area but a small surface area with a small covering portion ratio in the housing, for example, activated carbon alone is not efficient. Rather, it is more effective to form the attraction film on a portion of the magnetic disk drive that has a large area occupied in the device, such as the inner wall of the housing. In addition, from the viewpoint of maintaining the cleanliness of the inside of the housing, it is desirable to form a highly adsorptive film over a wide area directly on the inner wall of the base or the inner wall of the cover, rather than by introducing an external material or the like.
Further, forming an uneven shape on the inner wall surface to increase the area of the covering portion further improves the effect of the present invention.

The adsorptive film of the present invention, of course, needs to be able to be formed as a clean film on any area of the inner wall of the housing base and the inner wall of the housing cover, in addition to the high adsorption performance. .

In the magnetic disk drive according to the present invention, a highly adsorbing thin film is formed on the inner wall of the magnetic disk housing as a coating film satisfying the above requirements. The inventor of the present invention has formed a highly adsorptive film for removing contaminants in a magnetic disk drive, which is formed of a carbon (C) material, titanium dioxide (TiO2), tin dioxide (SnO2), diiron trioxide (Fe2O3), or the like. It has been found that a thin film is suitable.

The carbon (C) -based material referred to here is a carbon (C) film containing carbon (C) alone or one or more elements such as hydrogen (H) and nitrogen (N). The carbon (C) film may be formed by a method of sputtering a graphite target with argon (Ar) gas, a method of forming the target by an ion beam of carbon (C) ions, or the like. Argon (A
r) Reactive sputtering for sputtering with a gas mixed with hydrogen or methane, or plasma CVD for decomposing a hydrocarbon gas such as methane with high-frequency plasma
A carbon (C) film containing hydrogen (H) can be formed by a (Plasma Enhanced Chemical Vapor Deposition) method or the like. Alternatively, a carbon (C) film containing nitrogen (N) can be formed by reactive sputtering in which a gas in which nitrogen is mixed with argon (Ar) is used.

The thickness of the carbon (C) -based film for obtaining sufficient adsorption performance is preferably 5 nm or more and 5 μm or less. The reason is that if the thickness is less than 5 nanometers, the film will not be a continuous film and the adsorption performance will be deteriorated. If the thickness exceeds 5 micrometers, the film will be easily peeled off due to the compressive stress of the film. If necessary, a silicon (Si) -based thin film may be formed as an intermediate adhesive layer to improve the adhesion to the inner wall of the housing.

Titanium dioxide (TiO2), tin dioxide (S
An oxide film such as nO2) or diiron trioxide (Fe2O3) can be formed by sputtering a target of each bulk material with argon (Ar) alone or an argon (Ar) gas mixed with oxygen. The thickness of these films is preferably not less than 5 nanometers and not more than 5 micrometers for the same reason as the carbon (C) -based film. If necessary, as in the case of a carbon (C) -based film, a silicon (Si) -based thin film can be formed as an adhesive layer to improve the adhesion to the inner wall of the housing.

It is preferable that the casing having the highly adsorbent film formed on the inner wall be baked before mounting various components.
By this baking treatment, the gas that has been adsorbed until then is removed, and the adsorption capacity can be maximized. Baking is usually performed at a temperature in the range of 70 ° C to 150 ° C,
The time is selected from a time range of not less than 12 hours. By forming such a highly adsorptive film on the inner wall of the housing, it is possible to provide a magnetic disk drive from which contaminants having higher adsorption energy are removed than in the case of using only a conventional adsorbent, for example, activated carbon alone.

The present inventor has found that the efficiency of removing gas contaminants is further improved by forming the inner wall of the housing not in a plane but in a shape having fine irregularities. This is because the substantial surface area of the covering portion of the inner wall of the housing increases, and the area where contamination can be adsorbed increases. The shape of the unevenness may be rectangular or saw-toothed. However, from the viewpoint of increasing the surface area, the ratio of depth and pitch (depth / pitch)
Should be as large as possible. In addition, it is preferable that the depth be 1 cm or less due to the restriction on the thickness of the housing. A housing having such fine irregularities can be produced by die-casting using a mold having appropriate irregularities.

Further, by providing a mechanism for cooling the housing in the magnetic disk drive having a highly adsorbing film formed on the inner wall of the housing as described above, the effect of reducing contamination inside the device is further improved. This has the effect of reducing the outgas from the contamination source by cooling the whole device, and the one-sided contamination by making the highly adsorbent film on the inner wall of the housing relatively cooler than the components inside the magnetic disk device. This has the effect of adsorbing to the inner wall of the housing. As a mechanism for cooling the housing from the outside, for example, air cooling by installing a fan or fin, cooling by a Peltier element, a heat pipe, and the like are effective.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings based on examples.

<Embodiment 1> FIG. 1 is a schematic sectional view of a magnetic disk drive showing a first embodiment of the present invention. A carbon (C) film having a thickness of about 20 nm was formed on the inner wall of the magnetic disk drive housing by a sputtering method in which a graphite target was sputtered with argon (Ar) gas. The inner wall of the housing referred to here is the inner wall of the housing base 12 and the housing cover 11 (the same applies to the inner wall of the housing hereinafter). After the formation of the carbon (C) film, the housing cover was baked at 100 ° C. for 5 hours and the housing base at 80 ° C. for 5 hours immediately before mounting the components. A long-term temperature acceleration test was performed using the apparatus in which the carbon (C) film was formed on the inner wall of the housing in this manner. At this time, the temperature acceleration condition was 70 ° C., and the operation mode was a random seek mode in which the head was moved to an arbitrary track position for an arbitrary time. During this test, read / write is performed periodically, so if a defect occurs due to the generation of the deposit on the head ABS or the sliding between the head and the disk, a read / write error appears. Therefore, whether or not a failure has occurred can be determined by observing the read / write characteristics. In this test, a read / write error occurred after about 6000 hours had elapsed. The time until the occurrence of the error was able to be lengthened by about 2.4 times compared with the following comparative example 1.

In addition, a silicon bonding layer is formed on the inner wall of the magnetic disk drive housing in advance by a sputtering method in which a silicon target is sputtered with an argon (Ar) gas, and a graphite target is sputtered with an argon (Ar) gas. A carbon (C) film was formed to a thickness of about 500 nm by a sputtering method. This apparatus was subjected to a long-term temperature acceleration test under the same conditions as described above. In this case, a read / write error occurred after about 4800 hours had elapsed. In this example, the time until the occurrence of an error could be increased by about 1.9 times as compared with Comparative Example 1 described below. FIG. 9 shows, together with the results and the results of Comparative Example 1 below, various high-adsorption films formed on the inner wall of the housing with the same configuration, and the read / write error generation time when a long-term temperature acceleration test was performed. Are shown together. In each case, the time until the occurrence of the error was significantly extended as compared with Comparative Example 1.

<Comparative Example 1> A long-term temperature acceleration test was performed using a conventional magnetic disk drive in which a highly adsorbing film was not formed on the inner wall of the housing as shown in FIG. in this case,
Activated carbon is filled as the adsorbent 10. At this time, the temperature acceleration condition was 70 ° C., and the operation mode was a random seek mode. In this comparative example, a read / write error occurred after a lapse of 2500 hours.

<Embodiment 2> FIG. 3 is a schematic sectional view of a magnetic disk drive showing a second embodiment of the present invention. The housing of the magnetic disk drive was molded using a mold in which saw-like irregularities were formed. 2 m depth on the molded housing inner wall
m, pitch irregularities of 0.5 mm were formed. On the inner wall of the housing, a silicon bonding layer is formed in advance by a sputtering method of sputtering a silicon target with argon (Ar) gas, and further a sputtering method of sputtering a graphite target with argon (Ar) and nitrogen (N2) gas. Carbon (C) with nitrogen (N)
The film was formed to a thickness of about 300 nm. After the formation of the carbon (C) film containing nitrogen (N), one
A baking process was performed on the housing base at 80 ° C. for 5 hours at 00 ° C. for 5 hours.

A long-term temperature acceleration test was performed using the apparatus in which the nitrogen (N) -containing carbon (C) film was formed on the inner wall of the housing in this manner. At this time, the temperature acceleration condition was 70 ° C., and the operation mode was a random seek mode. As a result of the test, a read / write error occurred after about 6,500 hours. In this case, the time until the occurrence of the error could be increased by about 2.6 times as compared with Comparative Example 1.

<Embodiment 3> FIG. 4 is a schematic sectional view of a magnetic disk drive showing a third embodiment of the present invention. A TiO2 film having a thickness of about 400 nm was formed on the inner wall of the housing by a sputtering method in which a titanium dioxide (TiO2) target was sputtered with argon (Ar) and oxygen gas. After forming the titanium dioxide (TiO 2) film, the housing was baked at 80 ° C. for 5 hours immediately before mounting the components.

Using the apparatus in which the TiO2 film was formed on the inner wall of the housing as described above, a long-term temperature acceleration test was performed.
At the time of the test, a Peltier device was installed on the upper part of the housing. At this time, the ambient temperature was 70 ° C., but the temperature outside the side of the housing was about 65 ° C. due to the cooling effect of the Peltier device. The operation mode was a random seek mode in which the head was moved to an arbitrary track position for an arbitrary time. As a result of the test, a read / write error occurred after about 8,000 hours. In this case, the time until the occurrence of the error was about 2.6 times longer than that of Comparative Example 2 described below.

In the present embodiment, the Peltier element is installed on the upper part of the housing of the magnetic disk drive, but the installation place is not limited to this. The installation location may be anywhere outside the housing as long as it can cool the highly adsorbent film on the inner wall of the housing.

<Comparative Example 2> A long-term temperature acceleration test was performed using a conventional magnetic disk device in which a highly adsorbing film was not formed on the inner wall of the housing as shown in FIG. At this time, the temperature acceleration condition was 65 ° C., and the operation mode was a random seek mode. In this comparative example, a read / write error occurred after 3,500 hours.

<Embodiment 4> FIG. 5 is a schematic sectional view of a magnetic disk drive showing a fourth embodiment of the present invention. A carbon (C) film having a thickness of about 500 nm was formed on the base inner wall 12 of the magnetic disk drive housing by a sputtering method of sputtering a graphite target with argon (Ar) gas. After forming the carbon (C) film, the casing was baked at 80 ° C. for 5 hours immediately before mounting the components. A long-term temperature acceleration test was performed using the apparatus in which the carbon (C) film was formed on the inner wall of the housing in this manner. At this time, the temperature acceleration condition was 70 ° C., and the operation mode was a random seek mode in which the head was moved to an arbitrary track position for an arbitrary time. A read / write error occurred after about 4000 hours. The time until the occurrence of the error was about 1.6 times longer than that of Comparative Example 1 described above.

<Embodiment 5> FIG. 6 is a schematic sectional view of a magnetic disk drive showing a fifth embodiment of the present invention. A carbon (C) film having a thickness of about 500 nm was formed on the inner wall 11 of the cover of the magnetic disk drive housing by a sputtering method of sputtering a graphite target with argon (Ar) gas. After the carbon (C) film was formed, the casing was subjected to a baking treatment at 100 ° C. for 5 hours immediately before mounting the components.

Using the apparatus in which the carbon (C) film was formed on the inner wall of the housing in this manner, a long-term temperature acceleration test was performed.
At this time, the temperature acceleration condition was 70 ° C., and the operation mode was a random seek mode in which the head was moved to an arbitrary track position for an arbitrary time. After about 3700 hours, a read / write error occurred. The time until an error occurred was about 1.5 times as long as that of Comparative Example 1.

<Embodiment 6> FIGS. 7 and 8 show the thickness of a carbon (C) film and the occurrence of a read / write error in a random seek test in a magnetic disk drive having a carbon (C) film formed on the inner wall of a housing. It is a graph showing the relationship of time. In this embodiment, a silicon bonding layer was formed in advance on the inner wall of the magnetic disk drive housing by a sputtering method, and then a carbon (C) film was formed by a sputtering method in which a graphite target was sputtered with an argon (Ar) gas. At this time, the thickness of the carbon (C) film is set to 3 to 2200 n.
m. After forming the carbon (C) film, the casing was baked at 80 ° C. for 5 hours immediately before mounting the components.

Using the apparatus in which the carbon (C) film was formed on the inner wall of the housing as described above, a long-term temperature acceleration test was conducted in a random seek mode at a temperature of 70 ° C. The result is shown in FIG.
As shown in FIG. The data plotted here are the results of evaluating three carbon (C) films for each carbon (C) film, expressed as a maximum value, an average value, and a minimum value.

As shown in FIG. 7, when the thickness of the carbon (C) film was 2200 nm, film peeling occurred due to compressive stress. Further, FIG. 8 showing the region of 100 nm or less in FIG. 7 in an enlarged manner shows that when the film thickness is 5 nm or more, the time until an error occurs is greatly extended, and the effect of improving the life of the device appears.

[0037]

As described in detail above, by forming a highly adsorbing film on the inner wall of the magnetic disk drive housing, contaminant gas having a large adsorption energy in the magnetic disk drive can be removed, and the life of the drive can be extended. High reliability can be achieved. The life of the device can be further extended by increasing the surface area by making the shape of the inner wall of the housing having the highly adsorptive film uneven, or by installing a cooling mechanism outside the housing.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic disk drive showing an embodiment of the present invention in which a highly adsorbing film is formed on an inner wall of a housing.

FIG. 2 is a sectional view of a conventional magnetic disk drive.

FIG. 3 is a cross-sectional view of a magnetic disk drive showing an embodiment of the present invention in which a highly adsorbing film is formed on an inner wall of a case having an uneven shape.

FIG. 4 is a cross-sectional view of a magnetic disk drive according to an embodiment of the present invention in which a highly adsorptive film is formed on an inner wall of a housing and a cooling mechanism is provided outside the housing.

FIG. 5 is a cross-sectional view of a magnetic disk drive showing an embodiment of the present invention in which a highly adsorptive film is formed on an inner wall of a housing base.

FIG. 6 is a cross-sectional view of a magnetic disk drive showing one embodiment of the present invention in which a highly adsorbing film is formed on an inner wall of a housing cover.

FIG. 7 is a graph showing a relationship between a thickness of a carbon (C) film formed on an inner wall of a housing and a read / write error occurrence time.

8 is a diagram showing a carbon (C) film having a thickness of 100 nm in FIG. 7;
It is an enlarged view of the following area.

FIG. 9 is a table collectively showing examples of various high adsorption films of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 drive unit, 2 head slider support unit, 3 spindle motor, 4 magnetic disk, 5 housing, 6 highly adsorbing film, 7 uneven shape of inner wall of housing, 8 cooling mechanism, 9 head slider, 10 adsorbent, 11
Case base, 12 Case cover.

Claims (6)

[Claims] 1. A magnetic disk device for storing information, a magnetic head for recording and reproducing information on and from the magnetic disk, and a magnetic disk device housing for housing the magnetic disk and components for supporting and driving the magnetic head. And a magnetic disk drive in which at least one surface portion of the inner wall of the housing is covered with a highly adsorptive film. 2. The housing comprises a housing base on which the magnetic disk, the magnetic head and the components are mounted, and a housing cover for covering the housing base, wherein an inner wall of the housing base and the housing are provided. 2. The magnetic disk drive according to claim 1, wherein one or both of the inner walls of the body cover are covered with a highly adsorptive film. 3. The high adsorptivity film according to claim 1, wherein the film is one of carbon, carbon containing one or more kinds of other elements, titanium oxide, tin oxide, and iron oxide. Magnetic disk unit. 4. The magnetic disk drive according to claim 1, wherein an uneven shape is formed on one or both surfaces of the inner wall of the housing base and the inner wall of the housing cover. . 5. The film thickness of said highly adsorbent film is from 5 nm to 5 μm.
The magnetic disk drive according to any one of claims 1 to 4, wherein: 6. The magnetic disk drive according to claim 1, further comprising a cooling mechanism outside the housing.