JPH05113392A - Method for evaluating durability of membrane - Google Patents

Abstract

PURPOSE:To easily, quantitatively and accurately evaluate the durability of the surface protective membrane of a magnetic disk by a method wherein a slide member is slid on a membrane to be slid while the surface roughness of the membrane is measured and the terminal of sliding is decided on the basis of the measured value. CONSTITUTION:Since each member is received in a vacuum container 7, the magnetic head 4 equipped with a slider rail held by a spring arm 5 is not levitated from the surface of the surface protective membrane of the magnetic disk 3 even when a magnetic disk 3 is rotated at a high speed to slide on the magnetic disk 3. An optical measuring element 6 is connected to a computer 8 and the processing of the measured data of the surface roughness of the surface protective membrane of the disk is performed and the computer 8 decides the terminal of the sliding on the disk 3 of the head 4 and the durability of the surface protective membrane is evaluated from the slide time or the sliding number of times from the start of the sliding of the head 4 on the disk 3 to the terminal of the sliding of the head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the durability of a thin film for protecting the surface of a magnetic disk used in, for example, an external storage device of a computer.

[0002]

2. Description of the Related Art In a magnetic disk device which is an external storage device of a computer, the performance improvement has been remarkable as the recording density / capacity is increased and the recording density / size is reduced.
To improve the recording density (linear recording density) of a magnetic disk device, the distance between the magnetic disk and the magnetic head (flying height)
It is important to miniaturize the size stably.

Conventionally, a magnetic head is levitated on a magnetic disk rotated at high speed, the front end of the slider rail surface of the magnetic head is formed into a sled shape, and a magnetic head element is provided at the rear end of the magnetic head (two-body slider). The above-mentioned object of performance improvement is achieved. According to this method, since the rigidity of the air film interposed between the magnetic disk and the slider rail surface of the magnetic head can be made large, it is possible to secure high flying stability and a minute flying height (submicron) of 1 μm or less.

In order to further improve the recording density in the future, it is necessary to further reduce the flying height of the magnetic head. The ultimate relationship between the magnetic disk and the magnetic head is the magnetic head. The contact recording method of contacting with the is beginning to be studied. In this contact recording method, how to reduce abrasion between the magnetic disk and the magnetic head is a problem, and in order to achieve this problem, it is important to improve and develop the surface protective film of the magnetic disk.

The conventional method for evaluating the durability of the surface protective film of a magnetic disk is as follows. First, a magnetic disk having a surface protective film for durability evaluation is rotated, and the slider rail surface of the magnetic head is slid on the surface protective film. The end point of the sliding was visually judged whether or not the surface protective film was abraded by the sliding of the slider rail surface of the magnetic head.

That is, when the surface protective film of the magnetic disk is abraded and the magnetic layer underneath is exposed, the reflectance of light is improved and the light is emitted white. When observing it, when the magnetic disk glows white, the end point of sliding of the magnetic head on the magnetic disk is set as the end point, and the durability of the surface protective film depends on the sliding time and the number of times from the start to the end of sliding. I was doing an evaluation.

[0007]

However, since the surface of the magnetic disk gradually shines white as the surface protective film is worn, it is difficult to decide where to end the sliding of the magnetic head on the magnetic disk. Since the end point of sliding of the slider rail surface of the magnetic head changes depending on the person who is measuring and the physical condition of the day, the evaluation of the durability of the surface protective film may vary from person to person and is not accurate. Therefore, there is a demand for a method of easily, quantitatively and accurately evaluating the durability of the surface protective film of the magnetic disk.

[0008]

In order to solve the above-mentioned problems, the present invention provides a method for evaluating the durability of a thin film by sliding a thin film used for a surface protective film, etc. The sliding member slides on the thin film to be slid while measuring in real time, the end point of sliding of the sliding member is judged based on the measured value, and the sliding time from the start to the end of sliding or The durability of the thin film is evaluated from the number of times of sliding.

In addition, the number of projections on the surface of the thin film, which exceeds a certain slice value obtained from the roughness curve measured in real time while the sliding member is sliding on the thin film to be slid, is more constant than before the sliding. The end point of sliding the sliding member on the thin film is defined as the time point at which the ratio is reduced, and the durability of the thin film is evaluated from the sliding time or the number of times of sliding from the start to the end of sliding.

Further, the roughness parameter values such as the center line average roughness Ra and the maximum roughness Rmax obtained from the roughness curve measured in real time by the sliding member during sliding of the thin film to be slid are the values before the sliding. The end point for sliding the sliding member on the thin film is defined as the time point when the value decreases by a certain value, and the durability of the thin film is evaluated from the sliding time or the number of times of sliding from the start to the end of sliding. is there.

[0011]

According to the thin film durability evaluation method of the present invention, the end point of sliding of the sliding member on the thin film to be slid is determined as in the conventional case.
Do not visually judge the presence or absence of wear on the thin film due to the sliding of the sliding member, slide the sliding member while measuring the surface roughness of the thin film to be slid in real time, and measure the measured value. Since the end point of the contact sliding of the sliding member is determined based on the above, the determination of the end point of sliding does not change depending on the person measuring the subject or the physical condition of the day, and there is no individual difference. The durability of the thin film can be correctly evaluated from the sliding time or the number of times of sliding from the start to the end of movement.

[0012]

FIG. 1 shows an example of a thin film durability evaluation apparatus for carrying out the thin film durability evaluation method of the present invention. A spindle 1 is rotated by a motor 2 and holds a magnetic disk 3 on which a surface protection thin film for durability evaluation is formed. Reference numeral 4 denotes a magnetic head having a head slider that slides on the surface protection thin film of the magnetic disk 3, and the magnetic head is a spring arm 5.
Is attached to a head arm (not shown) via.
This head arm is attached to a carriage (not shown) having a seek function, and the track position of the magnetic disk 3 on which the magnetic head 4 slides can be freely changed.

Reference numeral 6 denotes a measuring device which is disposed behind the magnetic head 4 with respect to the rotating direction of the magnetic disk 3 and moves in the radial direction of the magnetic disk 3 together with the magnetic head 4 to measure the surface roughness of the surface protective thin film. Since various well-known optical measurement elements have been developed, detailed description thereof will be omitted. For example, a laser is applied to the surface of the surface protection thin film, and the surface is changed by the change of the reflected light. The roughness of the surface of the protective thin film is measured.

Since each member described above is housed in the vacuum container 7, the magnetic head 4 provided with the slider rail held by the spring arm 5 has its surface even when the magnetic disk 3 rotates at a high speed. The magnetic disk 3 slides without flying above the surface of the protective thin film.

The optical measuring element 6 is connected to a computer 8 and processes measured data of the surface roughness of the surface protective thin film of the magnetic disk 3, and as will be described later, the computer 8 uses the magnetic head. When the end point of the sliding of the magnetic disk 3 of 4 onto the magnetic disk 3 is determined, the computer 8
The motor controller 9 connected to stops the rotation of the motor 2 that rotationally drives the spindle 1 holding the magnetic disk 3. Reference numeral 10 is a display connected to the computer 8.

FIG. 2 schematically shows the magnetic disk 3, the magnetic head 4, and the optical measuring element 6, and the arrow indicates the direction of rotation of the magnetic disk 3. As is well known, in order to prevent the magnetic head 4 from sticking to the surface of the magnetic disk 3, fine concavities and convexities are formed in the circumferential direction of the disk substrate during the manufacturing process of the magnetic disk 3, and the fine concavities and convexities are sequentially formed on it. Since the magnetic layer and the surface protection thin film 3a are formed, the surface of the surface protection thin film 3a has irregularities as shown in the drawing.

FIG. 3 shows the surface protection thin film 3a of the magnetic disk 3.
The roughness curve of the magnetic disk 3 is measured by the optical measuring element 6 and the measured data is processed by the computer 8 to be displayed on the display 10.
Is a roughness curve before sliding the magnetic head 4, (b) is a roughness curve at the end point of sliding of the magnetic head 4 determined by the determination method described later, and O is a center line of the roughness curve. , L are slice levels having a constant height from the center line O, and the slice level is defined as the center line average roughness Ra.

Both of the roughness curves shown in FIGS. (A) and (b) are roughness curves for one round on the same track of the magnetic disk 3, and the roughness curves before and after the sliding of the magnetic head may change. Determine the end point of sliding of the magnetic head. The determination of the end point is performed by setting the centerline average roughness Ra to the slice level L and by the reduction rate of the number of protrusions exceeding the slice level L, or by determining the centerline average roughness Ra or the maximum roughness Rmax.
Based on roughness parameters such as.

As an example of a method for determining the end point of sliding of the magnetic head, based on a roughness curve measured by the optical measuring element 6, processed by the computer 8 and displayed on the display 10. (1) When the number of protrusions exceeding the slice level (10 nm) is 50% (50) before sliding (100). (2) The center line average roughness Ra is 80 before sliding (10 nm).
When the value (%) reaches 8%. (3) Maximum roughness Rmax is 80 before sliding (100 nm)
When the value reaches 80%. The end point of the sliding of the magnetic head is determined by any of the above.

Then, the durability of the surface protection thin film is evaluated from the sliding time or the number of times of sliding from the start of sliding of the magnetic head to the magnetic disk to the end of the sliding based on the above judgment. Is.

In this embodiment, the roughness parameter and the change in the number of protrusions exceeding the slice level of the roughness curve are used as parameters for determining the end point of sliding of the magnetic head on the magnetic disk. Any parameter that can evaluate the surface shape of the surface protection thin film of the magnetic disk may be used as an alternative means for determining the end point.

FIG. 4 shows a working procedure of the thin film durability evaluation method of the present invention. First, in step (1), the magnetic disk 3 is attached to the spindle 1, and then
In step (2), a sliding track on the magnetic disk 3 on which the magnetic head 4 slides is set.

Next, in step (3), the magnetic head 4 having the slider and the optical measuring element 6 are set on the sliding track of the magnetic disk 3. Next, in step (4), the surface roughness of the magnetic disk 3 before the magnetic disk 3 is rotated and the magnetic head 4 is slid is measured by the optical measuring element 6 for one track, and the measured data is obtained. Processed by computer 8, centerline average roughness R
a is calculated, this center line average roughness Ra is set as a slice level, and the number of protrusions of the surface protection thin film 3a of the magnetic disk 3 exceeding this slice level is calculated.

Next, in step (5), the air in the vacuum container 7 is evacuated so that the slider rail of the magnetic head 4 contacts the magnetic disk 3 by the spring pressure of the spring arm 5. Next, in step (6), the magnetic disk 3 is rotated to start sliding the magnetic head 4 on the magnetic disk 3.

Next, in step (7), the surface roughness of the magnetic disk 3 is measured by the optical measuring element 6 in real time while the magnetic head 4 slides on the magnetic disk 3, and the measured data is measured by the computer 8. After processing, the number of protrusions exceeding the slice level determined before the sliding of the magnetic head 4 is calculated.

Next, in step (8), the computer 8 judges whether or not the number of protrusions exceeding the slice level after sliding is 50% or less of the number of protrusions exceeding the slice level before sliding. , 50% or less (Ye
s), in step (9), the computer 8 causes the motor controller 9 to stop the rotation of the motor 2 that rotationally drives the spindle 1 holding the magnetic disk 3. That is, the end point of sliding of the magnetic disk 3 by the magnetic head 4 is determined.

Then, the durability of the thin film formed on the surface of the magnetic disk 3 can be evaluated from the sliding time or the number of times of sliding from the start to the end of sliding of the magnetic disk 3 by the magnetic head 4.

FIG. 5 is a block diagram of an apparatus for evaluating the durability of the surface protection thin film of the magnetic disk, and FIG. 6 is from the acquisition of the surface roughness curve of the surface protection thin film of the magnetic disk to the determination of the end point of sliding of the magnetic head. The flow chart of FIG.

First, in step (1) of FIG. 6, the track 1 before the magnetic head 4 slides on the magnetic disk 3
The surface roughness curve of the circumference is measured by the optical measuring element 6 and the computer 8, and the measured data is stored in the memory 1.

Next, in step (2), the computer 8 calculates the centerline average roughness Ra based on the measured surface roughness curve, and in step (3), the centerline average roughness Ra is sliced. The level is set and is stored in the memory 2.

Next, in step (4), the computer 8 calculates the number of protrusions exceeding the slice level in the surface roughness curve stored in the memory 1, and stores it in the memory 3.

Next, in step (5), sliding of the magnetic head 4 on the rotating magnetic disk 3 is started. Then, in step (6), the memory 1
Since it is unnecessary to store the roughness curve before sliding stored in, clear it.

Next, in step (7), the surface roughness curve of one track is measured by the optical measuring element 6 and the computer 8 while the magnetic head 4 is sliding on the magnetic disk 3, and the measured surface roughness curve is stored in the memory 1. Remember.

Next, in step (8), the computer 8 calculates the number of protrusions in the surface roughness curve during sliding, which exceeds the slice level stored in the memory 2, and stores it in the memory 4. To do.

Next, in step (9), the number of protrusions before sliding stored in the memory 3 is compared with the number of protrusions after sliding stored in the memory 4, and after sliding The computer 8 judges whether the number of projections exceeding the slice level of is less than 50% of the number of projections exceeding the slice level before sliding, and when it is less than 50% (Yes), in step (10). Then, the end point of the sliding of the magnetic disk 3 by the magnetic head 4 is determined, and in step (11), the computer 8 turns off the power of the motor 2 that rotationally drives the spindle 1 holding the magnetic disk 3 via the motor controller 9. , Stop the rotation of the motor 2 or generate an alarm.

The number of protrusions exceeding the slice level after sliding is 50 times the number of protrusions exceeding the slice level before sliding.
When it is not less than% (No), step (1
In 2), the memory of the memory 4 is cleared, and the process returns to step (6).

[0037]

As described above, according to the present invention, in the method for evaluating the durability of a thin film by sliding a thin film used for a surface protective film, etc., the surface roughness of the thin film to be slid is measured in real time. Slide the moving member on the thin film to be slid,
A thin film characterized in that the end point of sliding of the sliding member is determined based on the measured value and the durability of the thin film is evaluated from the sliding time or the number of times of sliding from the start to the end of sliding. Durability evaluation method. In addition, the number of protrusions on the surface of the thin film that exceeds the slice level of a certain constant value obtained from the roughness curve measured in real time while the sliding member slides on the thin film to be slid is
The end point of sliding the sliding member on the thin film was defined as the end point at which it decreased by a certain percentage from before the sliding, and the durability of the thin film was evaluated from the sliding time or the number of times of sliding from the start to the end of sliding. The durability evaluation method of the thin film according to claim 1, wherein Further, the roughness parameter values such as the center line average roughness Ra and the maximum roughness Rmax obtained from the roughness curve measured in real time while the sliding member is sliding on the thin film to be slid are
The time when the sliding member slides on the thin film is defined as the end point when it decreases by a certain value from before sliding, and the durability of the thin film is evaluated from the sliding time or the number of times of sliding from the start to the end of sliding. The durability evaluation method for a thin film according to claim 1, wherein Therefore, unlike the conventional method, the end point of sliding of the sliding member to the thin film to be slid is not visually judged whether the thin film is worn due to the sliding of the sliding member. The sliding member is slid while measuring the surface roughness of the sliding member in real time, and the end point of sliding of the sliding member is determined based on the measured value. The determination of the end point does not change depending on the person measuring the condition or the physical condition of the day, and individual differences do not occur, and the durability of the thin film can be correctly evaluated from the sliding time from the start of sliding to the end point or the number of times of sliding. ..

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a thin film durability evaluation apparatus for carrying out the thin film durability evaluation method of the present invention.

FIG. 2 is a diagram schematically showing a magnetic disk, a magnetic head, and an optical measuring element.

FIG. 3 is a diagram showing a comparison of roughness curves before and after sliding of a surface protection thin film of a magnetic disk.

FIG. 4 is a diagram showing a work procedure of a thin film durability evaluation method of the present invention.

FIG. 5 is a block diagram of an apparatus for evaluating the durability of a surface protective thin film of a magnetic disk.

FIG. 6 is a flow chart up to the determination of the sliding end point of the surface protection thin film of the magnetic disk.

[Explanation of symbols]

 1 Spindle 2 Motor 3 Magnetic Disk 3a Surface Protection Thin Film 4 Magnetic Head 5 Spring Arm 6 Optical Measuring Element 7 Vacuum Container 8 Computer 9 Motor Controller 10 Display

Claims (3)

[Claims] 1. A method for evaluating the durability of a thin film by sliding a thin film used as a surface protective film, etc., wherein a sliding member is slid on the thin film to be slid while measuring the surface roughness of the thin film to be slid in real time. The end point of sliding of the sliding member is determined based on the measured value, and the durability of the thin film is evaluated from the sliding time or the number of times of sliding from the start to the end of sliding. Method for evaluating the durability of thin film. 2. The number of protrusions on the surface of the thin film, which exceeds a certain slice value obtained from the roughness curve measured in real time while the sliding member slides on the thin film to be slid, is constant before the sliding. The durability of the thin film is evaluated from the time when the sliding member slides on the thin film as the end point at which the ratio is reduced, and the thin film durability is evaluated from the sliding time or the number of times of sliding from the start to the end of sliding. Item 3. A method for evaluating the durability of a thin film according to Item 1. 3. A center line average roughness R obtained from a roughness curve measured in real time while the sliding member slides on the thin film to be slid.
The sliding time from the start to the end of sliding is defined as the end point of sliding the sliding member on the thin film when the roughness parameter value such as a or maximum roughness Rmax decreases by a certain value from before the sliding. Alternatively, the durability evaluation method of the thin film according to claim 1, wherein the durability of the thin film is evaluated from the number of times of sliding.