JP2751907B2 - Magnetic disk drive and method for monitoring gas concentration in the magnetic disk drive - Google Patents

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 method of monitoring a gas concentration in a head disk assembly mounted on the magnetic disk drive.

[0002]

2. Description of the Related Art A head disk assembly (hereinafter referred to as HDA) of a magnetic disk drive includes a spindle motor having a magnetic disk, a head stack assay (HSA) having a magnetic head, and the like on a base portion or a cover portion. Installed and incorporated. Normal,
The portion where the respective openings of the base portion and the cover portion are engaged with each other is pressed through a gasket, and
The humidity and the degree of sealing are ensured to avoid the influence of corrosive gas existing in the external environment. In addition, a plastic sealing label is often attached to an opening for performing dust measurement, inspection, and connection of a servo track writer (STW).

[0003] As described above, the HDA has a sealed structure except for the respiratory port. However, when a temperature difference between the inside and the outside of the HDA of the magnetic disk device and an airflow due to the rotation of the magnetic disk occur, the HDA is slightly reduced. There is a joint of HDA,
Inflow of outside air from gaps such as gaskets and screw holes is inevitable. A breathing filter is usually attached to the breathing opening. When a chemical filter using a gas adsorbent is added to this breathe filter as well as a dust filter for the purpose of removing dust, it absorbs corrosive gas within the capacity of the gas adsorbent. Incoming corrosive gases can be prevented. However, the corrosive gas may flow in from gaps other than the breathing port, and there is no defense against this flow.

Conventionally, a magnetic disk device has been used as an external storage device of a large computer, and has been installed in a computer room equipped with air conditioning equipment. However, with the recent spread and portability of office computers, EWSs, personal computers, and the like, various computers have been used regardless of the installation environment. Therefore, there is an increasing possibility that a magnetic disk device mounted in a computer in a built-in or external form is placed in a bad environment. If a corrosive gas is present in the installation environment, the corrosive gas enters the inside of the HDA through the gap between the HDAs, and its concentration gradually increases. The element portion of the magnetic head and the medium layer of the magnetic disk may be corroded, and there has been a concern about the influence of corrosive gas. In recent high-density magnetic disk devices, head flying and head and disk smoothing have been progressing. H
(Describes DI).

[0005] As an example of the prior art, there is a "Survey of the installation environment of a computer by the metal test piece method" (Nakajima et al .: IEICE Technical Report
M92-176, 1993-03, IEICE)
(Hereinafter referred to as Document 1),
In order to measure the concentration of corrosive gas existing in the installation environment of computers, communication equipment, etc. as a long-term accumulation, Ag,
There is a method in which a metal test piece of Cu, Fe-Ni, Al, or Fe (hereinafter, referred to as a coupon) is provided and the determination is made based on the degree of discoloration of the coupon.

Further, there is an invention of a magnetic disk assembly described in Japanese Patent Application Laid-Open No. Hei 5-182444 (hereinafter, referred to as Japanese Patent Application Laid-Open No. 5-182444). The invention described in Publication 1
An object of the present invention is to provide a magnetic disk assembly that prevents the magnetic disk surface from being corroded by the corrosive gas in the HDA internal air and constantly cleans the internal air.
The base surface of the DA and the inner wall surface of the cover are subjected to a surface treatment with a material mainly composed of Ag or Cu, and corrosive gas is taken into the surface treatment.

[0007]

In the case where a chemical filter using a gas adsorbent as well as a dust filter for removing dust is added to the breathe filter attached to the breathing port of the HDA, the Can be adsorbed, but if the adsorbent's adsorption capacity is exceeded, the increase in the internal corrosive gas concentration cannot be prevented. Further, the corrosive gas may flow from various gaps of the HDA other than the breathing port, and in this case, the corrosive gas enters the HDA as it is. Furthermore, since the gas concentration in the external environment of the magnetic disk device varies, the gas concentration in the HDA is not always maintained as designed, and the corrosive gas reaches a high concentration in a short period of time, and H
A DI failure can occur and valuable stored data can be lost.

In order to solve these problems, monitoring of the accumulation state of the corrosive gas concentration for a certain period of time by attaching a coupon to an installation environment of electronic equipment has been conventionally performed. However, it has not been possible to know the corrosive gas concentration in a sealed environment such as inside an electronic device, especially inside an HDA of a magnetic disk device. Further, in the case of measurement using a coupon, there is a visual comparison with a color sample to know the result in a short time, but it lacks quantitativeness. Further, it is said that quantitative analysis can be performed to some extent by chemically analyzing the discolored coupon, but this is not sufficient, and this method is a batch process of destructive measurement.
There is a problem that it is impossible to simultaneously monitor the gas concentration inside A.

As described above, conventionally, the discolored coupon has been removed and visually compared with a color sample or subjected to chemical analysis. Therefore, the HD mounted on the magnetic disk device and sealed.
The coupon could not be applied for the purpose of automatically monitoring the corrosive gas concentration inside A.

In view of the foregoing, the present invention provides a magnetic disk drive that easily monitors the concentration of corrosive gas in an HDA, stops the magnetic disk drive before reaching a dangerous state, and prevents a failure of the magnetic disk. Another object of the present invention is to provide a method for monitoring the concentration of corrosive gas inside a device.

[0011]

[Means for Solving the Problems]

(1) A magnetic disk drive according to the present invention is a magnetic disk drive having a head disk assembly including an envelope, a head carriage, a magnetic head, a magnetic disk, and a motor, wherein the head disk assembly has a metal test piece therein. Wherein the metal test piece comprises a substrate having one of a conductive substrate and a non-conductive substrate, and the corrosive gas concentration is measured using the metal test piece. At this time, the substrate includes at least one metal thin film, and the metal thin film has
g, Cu, Fe-Ni, one kind of metal of Al and Fe can be provided. An electric resistance measuring unit for measuring a change in electric resistance between two opposing sides of the metal thin film; and a motor for controlling an operation of the motor. Control means.

In the method for monitoring gas concentration in a magnetic disk drive of the present invention, the electric resistance measuring means measures a change in electric resistance between two opposing sides of the metal thin film, and the electric resistance is set in advance. When the value exceeds the set value, the motor control means controls the operation of the motor to stop the operation of the magnetic disk device.

(2) The magnetic disk drive of the present invention is
The metal thin film includes a pattern, and a distance between one end and the other end of the pattern is set to a distance between two ends of the metal thin film.
It can be larger than the distance between the sides.

In the method for monitoring gas concentration in a magnetic disk drive according to the present invention, the electric resistance measuring means may include an electric resistance between one end and the other end of the pattern provided on the metal thin film. The change in the value is measured, and when the electric resistance value becomes larger than a preset value, the motor control means controls the operation of the motor to stop the operation of the magnetic disk device.

(3) In the magnetic disk drive of the present invention, the head disk assembly may include an irradiating means for irradiating the metal test piece with light, and a reflected light amount for detecting light reflected from the metal test piece. A detecting means; a reflected light quantity measuring means for measuring a change in the reflected light quantity detected by the reflected light quantity detecting means; and a motor control means for controlling the operation of the motor.

In the method for monitoring gas concentration in a magnetic disk drive according to the present invention, the irradiating means irradiates the metal test piece with light, and the reflected light amount detecting means detects light reflected from the metal test piece. The reflected light amount measuring means measures a change in the reflected light amount detected by the reflected light amount detecting means, and when the reflected light amount becomes smaller than a preset value,
The motor control means controls the operation of the motor to stop the operation of the magnetic disk device.

Here, the measurement of the change in the amount of reflected light is performed on the same principle as that of a pickup of a compact disk.
That is, a light emitting diode (hereinafter, referred to as an LED)
Since the laser light emitted from is reflected by the coupon,
This change in the amount of reflected light is detected by a detector. Further, by measuring the change in the color of the coupon, the type of the reaction product due to the corrosive gas can be known.

(4) Further, in the magnetic disk drive of the present invention, the substrate includes a transparent non-conductive substrate, and the head disk assembly irradiates the metal test piece with light; The apparatus includes a transmitted light amount detecting unit that detects light transmitted through the test piece, a transmitted light amount measuring unit that measures a change in the transmitted light amount detected by the transmitted light amount detecting unit, and a motor control unit that controls an operation of the motor.

In the method for monitoring gas concentration in a magnetic disk drive according to the present invention, the irradiating means irradiates the metal test piece with light, and the transmitted light quantity detecting means detects light transmitted through the metal test piece. The transmitted light quantity measuring means measures a change in the transmitted light quantity detected by the transmitted light quantity detecting means, and when the transmitted light quantity becomes larger than a preset value, the motor control means controls the operation of the motor. The operation of the magnetic disk device is stopped.

Here, the change in the amount of transmitted light is measured by detecting the change in the amount of light with a sensor. Also,
By measuring the change in the color of the coupon, the type of the reaction product due to the corrosive gas can be known.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a method of detecting a change in a coupon on the spot, focusing on the fact that a change in the coupon due to a corrosive gas is reflected on an electric resistance value and an optical change. We propose a coupon that can be easily detected.

Specifically, by forming a metal thin film on a non-conductive substrate, it is possible to measure a change in the electric resistance value of the metal thin film. Further, by forming a pattern on the metal thin film, it is easy to measure the change in the electric resistance value. Further, by forming a metal thin film on a substrate, a change in the amount of reflected light can be easily measured. When measuring the change in the amount of transmitted light, the change in the amount of transmitted light can be easily measured by using a transparent substrate.

These measurements are performed by sensors installed in the HDA in combination with coupons. By transmitting a signal detected by the sensor to the control circuit, an alarm can be issued or the rotation of the magnetic disk can be stopped when the corrosive gas concentration approaches a dangerous concentration. Since an electrical signal is output from the sensor, it is easy to take it out of the HDA. The signal is transmitted to a package usually mounted on the back side of the HDA, and the control circuit in the package automatically detects the corrosive gas concentration. Measurements, predict dangers, and prevent failures. At this time, if the package containing the control circuit is mounted inside the HDA,
There is no need to take the signal out of the HDA.

The coupon in the present invention may be a flake or metal foil made of metal only. However, in order to measure the change in the electric resistance value, it is desirable that the thickness be several tens μm or less, preferably several μm or less. It is preferable to adopt a structure in which a metal thin film is formed. As the non-conductive substrate, glass, quartz, various plastics, resin tape, and the like can be used. On nonconductive substrates, dry plating methods such as sputtering, vapor deposition, ion plating,
Alternatively, a metal thin film of Ag, Cu, Fe—Ni, Al, Fe, or the like can be formed by a wet plating method such as an electroplating method or an electroless plating method.

In the case of using the electroplating method, it is necessary to previously form a seed layer on the surface of the non-conductive substrate by a dry plating method. In the case of the electroless plating method, it is necessary to form a seed layer on the surface of the non-conductive substrate by a dry plating method or to perform a catalyzing treatment. As the catalyzing treatment, an activation treatment, which is a pretreatment for plastic plating, can be used. This includes a two-step activation treatment method of sensitization treatment with a tin chloride solution performed in an acidic region and activation treatment with a palladium chloride solution, and a tin / palladium colloidal catalyst solution and an acid.
There are a one-step activation treatment method comprising an accelerating treatment using an alkali solution and an activation treatment method using a one-step activation treatment method using a tin / palladium complex catalyst solution performed in an alkaline region. There is also a method of painting the surface with a paint in which a catalytic metal powder such as silver is dispersed. When a pattern is formed on the metal thin film thus formed, a method of exposing a photoresist to form a resist pattern and then etching with an acid can be used.

In the case of a coupon for forming a metal thin film on a transparent substrate, the non-conductive substrate is the same as the non-conductive substrate except that the above-mentioned transparent material such as glass, quartz, various plastics, and resin tape is used as the non-conductive substrate. It can be manufactured in the same manner as in the case of a coupon for forming a metal thin film thereon.

It is desirable that the thickness of the metal thin film is several μm or less, preferably 1 μm or less. When measuring the concentration of corrosive gas by changing the transmitted light of a coupon having a metal thin film formed on a transparent substrate, the concentration is preferably 0.1 μm or less, more preferably 0.02 μm or less.

The metal surface of the coupon undergoes a chemical reaction and changes due to the corrosive gas.
The chemical reactions differ depending on the type of corrosive gas and the type of metal of the coupon, as described in US Pat. In the reaction of hydrogen sulfide gas (H ₂ S) or chlorine gas (Cl ₂ ) with silver,
It produces silver sulfide (Ag ₂ S) and silver chloride (AgCl).
Hydrogen sulfide gas (H ₂ S), chlorine gas (Cl ₂ ), sulfur dioxide gas (SO ₂ ), or nitrogen dioxide gas (NO ₂ )
In the reaction between copper and copper, copper hydroxide (Cu ₂ O, CuO), basic copper sulfate (3Cu (OH) ₂ .CuSO ₄ ), chloride (3Cu (OH) ₂ .CuCl ₂ ), copper sulfide (CuS ,
Cu ₂ S) and the like are generated.

That is, SO ₂ and H ₂ S are Ag, Cu,
Since a sulfide of Fe—Ni is generated, a chlorine gas generates a chloride of Ag and Al, and a water vapor generates an oxide such as Fe, the coupon changes its color depending on the gas type. The discoloration of the copper coupon, such as yellowish brown with SO ₂ , blue black with H ₂ S and dark brown with HCl,
Table 1 of the above-mentioned document 1 describes the color tone of a corrosion product of a metal caused by a corrosive gas.

Since these products have low electric conductivity,
The electric resistance value of the coupon increases. In addition, since these products often have low light reflectance, the amount of reflected light decreases. Further, since these products often have high light transmittance, the amount of transmitted light increases. Therefore, the degree of accumulation of corrosive gas inside the HDA can be known by detecting a change in the electric resistance value, reflected light amount, or transmitted light amount of the coupon.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment and a second embodiment of the present invention will be described below with reference to the drawings.

[1] First Embodiment FIG. 1 is a cross-sectional view of an HDA according to a first embodiment of the present invention. By measuring the change in the electric resistance of a metal thin film of a coupon, a magnetic disk drive is measured. FIG. 4 is a diagram for explaining a method of monitoring the corrosive gas concentration inside the HDA.

The HDA shown in FIG. 1 includes an HDA base cover 1, a head carriage 2, a magnetic head 3, a magnetic disk 4, a breathing opening 5, and a metal thin film 6 of a coupon.
And the non-conductive substrate 7 of the coupon and the electrical resistance value measuring unit 8
, A motor control unit 9, a spindle motor 10, and a package 11. In the first embodiment, since the Fe thin film is used as the metal thin film 6 of the coupon, it will be described as the Fe thin film 6 hereinafter. As the corrosive gas, a sulfur dioxide gas is considered.

The HDA base cover 1 serving as an HDA case is connected via a gasket and has a breathing port 5.
The other parts are closed to form a closed structure. But H
There is a leak from the DA coupling portion, the screw hole, the spindle motor 10 and the like, and the inflow of outside air is inevitable, albeit little by little.

Inside the HDA, a coupon in which an Fe thin film 6 is formed on a non-conductive substrate is attached, and terminals are provided on two opposite sides of the Fe thin film 6, respectively. A lead wire is taken out from the terminal of the Fe thin film 6 to the outside of the HDA.
It is connected to the electric resistance value measuring unit 8 and the motor control unit 9 of the package attached to the lower part of the DA. The electric resistance output from the terminal of the Fe thin film 6 via the lead wire is measured by the electric resistance measuring unit 8 and further input to the motor control unit 9 for controlling the spindle motor 10.

When the sulfur dioxide gas enters as a corrosive gas into the HDA and elapses, a compound having a film thickness corresponding to the concentration of the sulfur dioxide gas and the elapsed time is formed on the Fe thin film 6. This is a red rust compound,
The electric conductivity of the Fe thin film 6 decreases and the electric resistance increases. The electric resistance measurement unit 8 monitors the concentration of corrosive gas inside the HDA of the magnetic disk device by measuring the change in the electric resistance of the Fe thin film 6. When the corrosive gas concentration exceeds the preset value and the electric resistance value becomes larger than the preset value, the motor control unit 9 activates the stop mechanism of the magnetic disk device. In this way, the magnetic disk device can be stopped before the dangerous state is reached.

In the first embodiment, the Fe thin film was used as the metal thin film. However, Ag, Cu, Fe--N
Similarly, when using a coupon formed with a metal thin film of i, Al, or the like, the concentration of various corrosive gases can be monitored by a change in electric resistance. Further, as the non-conductive substrate, the above-mentioned glass, quartz, various plastics, resin tapes and the like can be used.

[2] Second Embodiment FIG. 2 is a plan view of a coupon according to a second embodiment of the present invention, in which a change in electric resistance of a pattern formed on a metal thin film of the coupon is measured. FIG. 7 is a diagram for explaining a method of monitoring the corrosive gas concentration inside the HDA of the magnetic disk device by using the method.

The coupon in the second embodiment is the same as the coupon in the first embodiment described with reference to FIG. 1, and can be applied to the HDA in FIG. In the second embodiment, a glass substrate is used as the non-conductive substrate. As the metal thin film, an Fe thin film is used as in the first embodiment.

The coupon shown in FIG. 2 is substantially square, and has eight grooves formed at regular intervals on the surface thereof. The Fe thin film has been removed from the portion where the groove has been formed, and the glass non-conductive substrate appears on the surface. Such a pattern is often used in an IC manufacturing process, by a process of photoresist coating → exposure → development → etching.
It can be easily manufactured.

The electric resistance value of the metal thin film is inversely proportional to the cross-sectional area and proportional to the length. By forming eight grooves as shown in FIG. 2 in the metal thin film at equal intervals, the sectional area becomes 1/9.
And the length from A to B is about 9 times. Therefore, the electric resistance value from A to B is about 81 times as compared with the case where no pattern is formed on the metal thin film. In the HDA shown in FIG. 1, by using the coupon shown in FIG. 2 to take out the lead wires to the outside with the portions of A and B as terminals, even if a metal thin film of the same area is used, the first embodiment The electric resistance of the coupon is about 81 times that of the
The corrosive gas concentration inside A can be monitored with high sensitivity.

In the second embodiment, the Fe thin film was used as the metal thin film, but Ag, Cu, Fe--N
Similarly, when a coupon in which a pattern is formed on a metal thin film of i, Al, or the like is used, the concentration of various corrosive gases can be monitored by a change in electric resistance. In addition, although a glass substrate was used as the non-conductive substrate, quartz other than glass,
Various plastics, resin tapes, and the like can be used.

[3] Third Embodiment FIG. 3 is a sectional view of an HDA according to a third embodiment of the present invention. By measuring a change in the amount of reflected light of the coupon, the inside of the HDA of the magnetic disk device is measured. It is a figure for explaining a method of monitoring corrosive gas concentration.

The HDA shown in FIG. 3 has an HDA base cover 1, a head carriage 2, a magnetic head 3, a magnetic disk 4, a breather port 5, a coupon 16,
The configuration includes a light reception detection unit 17, a reflected light amount measurement unit 18, a motor control unit 9, a spindle motor 10, and a package 11. Also, the light emission / light reception detection unit 17
Has an LED 17a and a detector 17b.
In the third embodiment, a coupon 16 is used in which a thin film of Al is formed on a polycarbonate substrate having a smooth surface. Further, chlorine gas is considered as the corrosive gas.

As in the first embodiment, the HD shown in FIG.
A also has a closed structure, but HDA also has various leaks, and the inflow of outside air is inevitable, albeit little by little.

A coupon 16 is mounted inside the HDA, and an LED 17a is arranged to face the surface of the coupon 16 on which the Al thin film is formed. LED 17a
The laser light emitted from is reflected by the Al thin film,
The light is guided to the detector 17b via a half mirror (not shown) arranged between the coupon and the LED 17a. A lead wire is drawn out of the HDA from the detector 17b, and is connected to the reflected light amount measurement unit 18 and the motor control unit 9 in a package attached below the HDA.
An electric signal output from the detector 17b via a lead wire is constantly measured for a change in the amount of reflected light by a reflected light amount measuring unit 18, and the signal is input to a motor control unit 9 that controls the spindle motor 10.

When chlorine gas as a corrosive gas enters the HDA and the time elapses, a compound having a film thickness corresponding to the concentration of the chlorine gas and the elapsed time is formed on the Al thin film of the coupon 16. Since this becomes a white rust-like compound, A
(1) The reflectance of light of the thin film decreases, and the amount of reflected light decreases. The reflected light amount measuring unit 18 monitors the concentration of corrosive gas inside the HDA of the magnetic disk device by measuring the change in the reflected light amount of the Al thin film. When the corrosive gas concentration exceeds a preset value and the amount of reflected light becomes smaller than the preset value, the motor control unit 9 operates the stop mechanism of the magnetic disk device. In this way, the magnetic disk device can be stopped before the dangerous state is reached.

In the third embodiment, an Al thin film was used as the metal thin film. However, Ag, Cu, Fe--N
Similarly, when a coupon having a metal thin film of i, Fe or the like is used, the concentration of various corrosive gases can be monitored by the change in the amount of reflected light. Further, although a polycarbonate substrate having a smooth surface is used as the non-conductive substrate, glass, quartz, various plastics, resin tapes, and the like other than polycarbonate can be used. Further, in the third embodiment, since the change in the amount of reflected light is measured, instead of the non-conductive substrate, Ni, Al
Etc. can be used. In this case, it is possible to use a metal plate alone as a coupon without forming a metal thin film.

[4] Fourth Embodiment FIG. 4 is a sectional view of an HDA according to a fourth embodiment of the present invention. By measuring a change in the amount of transmitted light of the coupon, the inside of the HDA of the magnetic disk device is measured. It is a figure for explaining a method of monitoring corrosive gas concentration.

The HDA shown in FIG. 4 has an HDA base cover 1, a head carriage 2, a magnetic head 3, a magnetic disk 4, a breather port 5, a coupon 16, an LED 17a as a light emitting section, and a light receiving section. Detector 1 that is a detection unit
7b, a transmitted light amount measurement unit 28, a motor control unit 9, a spindle motor 10, and a package 11. In the fourth embodiment, coupon 16
Used is a polycarbonate substrate having a smooth surface and an Fe thin film formed on the substrate. In addition, steam is considered as the corrosive gas.

As in the first embodiment, the HD shown in FIG.
A also has a closed structure, but HDA also has various leaks, and the inflow of outside air is inevitable, albeit little by little.

A coupon 16 is mounted inside the HDA, and an LED 17a and a detector 17b are arranged with the coupon 16 interposed therebetween. In FIG. 4, a detector 17b is arranged to face the surface of the coupon 16 on which the Fe thin film is formed. A lead wire is taken out of the HDA from the detector 17b, and is connected to the transmitted light amount measurement unit 28 and the motor control unit 9 in the package attached below the HDA. An electric signal output from the detector 17b via a lead wire is constantly measured for a change in the amount of transmitted light by a transmitted light amount measurement unit 28, and the signal is input to a motor control unit 9 that controls the spindle motor 10.

In a state before the corrosive gas enters, the laser light emitted from the LED 17a is blocked by the Fe thin film of the coupon 16, and the transmitted light amount detected by the detector 17b is almost nil. However, HDA
When water vapor enters as a corrosive gas and elapses of time, a compound having a film thickness corresponding to the concentration of the water vapor and the elapsed time is formed on the Fe thin film of the coupon 16. This is F
Since it becomes an oxide of e, the light transmittance increases and the amount of transmitted light increases as compared with the state of Fe. The transmitted light amount measuring unit 28 monitors the concentration of corrosive gas inside the HDA of the magnetic disk device by measuring a change in the amount of transmitted light through the coupon. When the corrosive gas concentration exceeds a preset value and the amount of transmitted light becomes larger than the preset value, the motor control unit 9 activates the stop mechanism of the magnetic disk device. In this way, the magnetic disk device can be stopped before the dangerous state is reached.

In the fourth embodiment, the Fe thin film was used as the metal thin film. However, Ag, Cu, Fe--N
Similarly, when a coupon formed with a metal thin film such as i or Al is used, the concentration of various corrosive gases can be monitored by the change in the amount of transmitted light. In addition, although a polycarbonate substrate having a smooth surface is used as the non-conductive substrate, a transparent substrate other than polycarbonate, such as glass, quartz, various plastics, and resin tapes can be used. Further, in FIG. 4, the detector 17b is arranged to face the surface of the coupon 16 on which the Fe thin film is formed.
The LED 17a may be arranged to face the surface of the coupon 16 on which the Fe thin film is formed.

In the coupons described in the first to fourth embodiments, one kind of metal thin film is formed on one substrate. ", Several types of metal thin films can be formed on one substrate. By doing so, the measurement corresponding to more types of corrosive gases can be performed by changing the metal thin film used according to the type of corrosive gas.

[0056]

As explained above, according to the present invention, Ag, Cu, Fe-Ni, A
When a corrosive gas enters the HDA of a magnetic disk drive by forming a metal thin film such as l, Fe, etc., a compound having a film thickness corresponding to the type and concentration of the corrosive gas and the elapsed time is formed on the coupon. The type, concentration, and accumulation state of the corrosive gas inside the HDA of the magnetic disk drive can be easily monitored by detecting the electrical change or optical change that occurs.

Further, the electric resistance value of the coupon, the amount of reflected light,
Alternatively, a dangerous state is reached by interlocking the electric resistance value measuring unit, the reflected light amount measuring unit, or the transmitted light amount measuring unit, which measures the change in the transmitted light amount, with the motor control unit, which is the stop mechanism of the magnetic disk device. The magnetic disk device can be stopped beforehand, and failure of the magnetic disk can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of an HDA according to a first embodiment of the present invention.

FIG. 2 is a plan view of a coupon according to a second embodiment of the present invention.

FIG. 3 is a sectional view of an HDA according to a third embodiment of the present invention.

FIG. 4 is a sectional view of an HDA according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 HDA base cover 2 Head carriage 3 Magnetic head 4 Magnetic disk 5 Breath opening 6 Metal thin film (Fe thin film) of a coupon 7 Non-conductive board of a coupon 8 Electric resistance measurement part 9 Motor control part 10 Spindle motor 11 Package 16 Coupon 17 Light emitting / receiving detector 17a LED 17b Detector 18 Reflected light amount measuring unit 28 Transmitted light amount measuring unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 19/22 G11B 19/22 A 25/04 101 25/04 101K

Claims (10)

(57) [Claims] 1. A magnetic disk drive having a head disk assembly including an envelope, a head carriage, a magnetic head, a magnetic disk, and a motor, wherein the head disk assembly has a metal test piece inside, and the metal test piece is A magnetic disk drive, comprising: a substrate having one of a conductive substrate and a non-conductive substrate; and measuring a corrosive gas concentration using the metal test piece. 2. The method of claim 1, wherein the substrate comprises at least one metal thin film, wherein the metal thin film comprises one of Ag, Cu, Fe—Ni, Al and Fe. The magnetic disk device according to the above. 3. The method according to claim 1, wherein the substrate includes a non-conductive substrate, the head disk assembly measures electric resistance change between two opposing sides of the metal thin film, and controls operation of the motor. 3. The magnetic disk drive according to claim 2, further comprising: a motor control unit for controlling. 4. An electric resistance measuring means for measuring a change in electric resistance between two opposing sides of the metal thin film, and when the electric resistance becomes larger than a preset value, the motor control means. 4. The method according to claim 3, wherein the controller controls the operation of the motor to stop the operation of the magnetic disk device. 5. The metal thin film according to claim 3, wherein the metal thin film has a pattern, and a distance between one end and the other end of the pattern is larger than a distance between two opposite sides of the metal thin film. The magnetic disk device according to the above. 6. The electric resistance measuring means measures a change in electric resistance between one end and the other end of the pattern provided on the metal thin film, and the electric resistance is measured beforehand. 6. The method according to claim 5, wherein the motor control means controls the operation of the motor and stops the operation of the magnetic disk device when the value becomes larger than a set value. . 7. The head disk assembly detects the light by irradiating the metal test piece with light, detecting the amount of light reflected from the metal test piece, and detecting the amount of reflected light by the reflected light amount detector. 3. The magnetic disk drive according to claim 1, further comprising: a reflected light amount measuring unit that measures a change in a reflected light amount; and a motor control unit that controls an operation of the motor. 8. The irradiating means irradiates the metal test piece with light, the reflected light quantity detecting means detects light reflected from the metal test piece, and the reflected light quantity measuring means uses the reflected light quantity detecting means. A change in the detected reflected light amount is measured, and when the reflected light amount becomes smaller than a preset value, the motor control means controls the operation of the motor to stop the operation of the magnetic disk device. 7. A method for monitoring a gas concentration in a magnetic disk device described in 7. 9. The apparatus according to claim 9, wherein the substrate comprises a transparent non-conductive substrate, the head disk assembly irradiating the metal test piece with light, and a transmitted light amount detecting means for detecting light transmitted through the metal test piece. Means, a transmitted light quantity measuring means for measuring a change in transmitted light quantity detected by the transmitted light quantity detecting means, and a motor control means for controlling the operation of the motor,
The magnetic disk drive according to claim 2. 10. The light irradiating means irradiates the metal test piece with light, the transmitted light quantity detecting means detects light transmitted through the metal test piece, and the transmitted light quantity measuring means detects with the transmitted light quantity detecting means. The change in the transmitted light amount is measured, and when the transmitted light amount becomes larger than a preset value, the motor control means controls the operation of the motor to stop the operation of the magnetic disk device. Monitoring method of the gas concentration in the magnetic disk device described in the above.