JPH04142444A - Abrasion resistance evaluating method for magnetic disk medium surface - Google Patents

Abstract

PURPOSE:To easily measure abrasion depth by bringing a lapping tape into contact and sliding it with the surface of a magnetic disk medium rotated at a constant speed, and measuring the abrasion depth after a preset period elapses. CONSTITUTION:A magnetic disk medium 5 is rotated at a constant speed. A lapping tape L is pressed into contact with the surface of the rotated magnetic disk medium 5. The preset load W is applied by the air force or a spring as the pressing force. The lapping tape L is kept in contact with the surface of the magnetic disk medium 5 at a fixed position. When the lapping tape L is pressed into contact with the surface of the rotated magnetic disk medium 5, the surface of the magnetic disk medium 5 is abraded in a true circular shape only at the position 9 where the lapping tape L is slid. The abrasion depth of the abrasion section 9 is measured after the sliding for a preset period.

Description

[Detailed Description of the Invention] (Summary) A method for evaluating the wear resistance of the surface of a magnetic disk medium, which is a recording medium of a magnetic disk device used as a file device in a computer system, and a magnetic disk medium having an extremely thin film. The objective is to realize a method that can efficiently and accurately evaluate the wear resistance of the surface of a magnetic disk in a short period of time. The method is characterized in that the wrapping tape is pressed against the surface of the magnetic disk and then slid, and after a predetermined period of time has elapsed, the depth of the portion of the surface of the magnetic disk medium that has been slid by the wrapping tape is measured.

[Field of Industrial Application] The present invention relates to a method for evaluating the wear resistance of the surface of a magnetic disk medium, which is a recording medium of a magnetic disk device used as a file device in a computer system.

In magnetic disk media, as recording density increases, the flying height of the magnetic head tends to become smaller, and is now 0.2 μm or less. As a result, the magnetic head tends to come into sliding contact with the magnetic disk medium, which may lead to a head crash due to abrasion particles.Therefore, there is a demand for a magnetic disk medium that is resistant to wear and has high durability. Therefore, there is a need to establish a method that can positively evaluate the wear resistance of the surface of a magnetic disk medium at the manufacturing stage of the magnetic disk medium.

[Prior Art] FIG. 6 is a sectional view of a thin film type magnetic disk medium. The thin film magnetic disk medium is AL with N1-P coating.
A base film 2 of Cr or the like, a magnetic film 3 of CoCrTa or the like, and a protective film 4 of C or the like are laminated in this order on a substrate l.

The film thickness of each layer is approximately 500 to 2000 for base film 2, approximately 200 to 600 for magnetic film 3, and 250 to 4 for protective film 4.
Approximately 00 people.

Evaluation of the wear resistance of a thin film type magnetic disk medium is nothing but evaluation of the wear resistance of the protective film 4 on the surface. Therefore, it is important to be able to accurately evaluate the wear resistance of the protective film 4 having a thickness of 500 Å or less.

Conventional methods for evaluating the wear resistance of magnetic disk media include ■Method using a Pickus hardness tester, ■Method of measuring the depth of indentation of a stylus under load, ■Method of observing drag marks caused by a stylus. 2) A method of sliding an actual magnetic head and observing the state of wear is known.

[Problems to be Solved by the Invention] The method (2) using a Pickus hardness tester is a method in which a square pyramid indenter is pressed against a magnetic disk medium and the length of the diagonal line of the square depression created at that time is measured. However, since the thickness of the protective film is extremely thin, 500 Å or less, as described above, the Pickus indenter reaches the magnetic film and the underlying film, and ultimately measures the hardness of the magnetic film and the underlying film as well. Furthermore, if a minute pressure is applied so as not to reach the magnetic film or the underlying film, the area of the indentation will be small and the length of the diagonal line will be impossible to measure.

To measure the size of the indentation, a film thickness of about 1 to 2 μm is required.

The method (2) of measuring the indentation depth of a stylus under a load differs from that of the above-mentioned Pickus hardness tester only in the use of an indenter, and basically has the same problems. Therefore, it is not suitable for evaluating the abrasion resistance of a thin film such as a protective film that can be worn on the order of several hundred people.

■The method of observing the drag marks caused by the stylus is described in Japanese Patent Application No.
-265514, and is the method described in No. 7
As shown in the figure, after a stylus 7 carrying a weight 6 with a predetermined load is dragged over a magnetic disk medium 5, drag marks on the surface of the medium are observed. That is, the presence or absence of cracks in the drag marks is determined. Cracks include chipping, median crack, and Hertzian crack, in which the protective film is damaged in a shell-like manner.

However, in this method, the load of the weight 6 is
In addition to the interface 8 between the stylus and the magnetic film 3, a tensile force F is generated at the interface 8 at the lower part of the stylus 7, and this tensile force F may cause cranking. As described above, since it is affected by the interfacial adhesion between the protective film 4 and the magnetic film 3, it is effective for evaluating the adhesion of the protective film 4, but it is difficult to accurately evaluate the hardness of the protective film 4. It is. In addition, since the type and degree of cracks are determined by visual observation, there is a problem that individual differences occur and it is difficult to quantify.

The method (2) of sliding an actual magnetic head and observing its wear condition is also described in Japanese Patent Application No. 1-296708, in which the magnetic head is placed on a continuously rotating magnetic disk medium. Slide it and observe the wear condition. This method of sliding has a problem in that when the condition of the sliding object changes, the wear condition also changes. In other words, the wear of the magnetic head progresses as measurements are performed, so in order to always perform accurate measurements, a large number of magnetic heads must be prepared for measurement if used magnetic heads are not reused. Otherwise, the cost will be high. Even if a new magnetic head is always used, the condition of each magnetic head is different, and the pressure force between the magnetic head supported by a thin plate spring and the rotating magnetic disk medium is uneven and unstable. Since it is impossible to completely eliminate this, reproducibility is lacking and accurate measurement is impossible. Furthermore, it takes time for the surface of the magnetic disk medium to wear out due to the core slider of the magnetic head, resulting in poor efficiency.

In addition, the method of dragging a stylus or sliding a core slider on the surface of the magnetic disk medium described in ■■ can also evaluate the adhesion between the protective film and the magnetic film beneath it, while the hardness measurement method of ■■ With this method, only local hardness can be measured, and the state of adhesion of the film cannot be evaluated.

The technical problem of the present invention is to focus on such problems and to realize a method that can efficiently and accurately evaluate the wear resistance of the surface of a magnetic disk medium having an extremely thin film in a short time. be.

(Means for Solving the Problems) Fig. 1 is a sectional view illustrating the basic principle of the method for evaluating the wear resistance of the surface of a magnetic disk medium according to the present invention. 5 is a magnetic disk medium, which rotates at a constant speed. L is a wrapping tape, which is in pressure contact with the surface of the rotating magnetic disk medium 5.The pressure contact force in this case is given by applying a predetermined load W by air force or springs. .

Further, the wrapping tape L is in contact with the surface of the magnetic disk medium 5 at a certain position.

In this way, by pressing the wrapping tape L against the surface of the rotating magnetic disk medium 5, the surface of the magnetic disk medium 5 is worn in a perfect circle only at the position 9 where the wrapping tape L has slid. In the method of the present invention, the wear depth of the worn portion 9 is measured after sliding for a predetermined period of time.

[Operation] Since the wrapping tape L is pressed to a fixed position on the rotating magnetic disk medium 5, only the position 9 where the roughing tape has slid is worn out in a relatively short time. Moreover, since the entire area pressed by the roughening tape L is worn, the depth of wear can be easily and accurately measured using a step measuring device, a film thickness meter, or the like.

In addition, since the surface of the magnetic disk medium is worn with a wrapping tape, the wear rate is fast and the wear resistance can be efficiently measured and evaluated in a short period of time.

(Example) Next, how the method for evaluating the wear resistance of the surface of a magnetic disk medium according to the present invention is actually implemented will be explained using an example. They are a plan view and a cross-sectional view of a sliding device.A support shaft 12 of a feeding roll 11 of a wrapping tape L, a support shaft 14 of a winding roll 13, a guide roller 15, a (wrapping ) tape feed roller 16
, the pinch roller 21 is mounted and supported. Also,
On the guide plate 17 attached between the side plates 10 and 10,
Wrapping) A shaft 19 to which a tape holder 18 is fixed is inserted, and a compression coil spring 20 is sandwiched between the tape holder 18 and the guide plate 17.

Now, when the tape feed roller 16 is rotationally driven by the motor M, the wrapping tape L fed out from the feed roll 11 is moved between the guide roller 15, the tape presser and the magnetic disk medium 5, and between the tape feed roller 16 and the pinch roller. 21 and then wound onto a winding roll 13.

The magnetic disk medium 5 to be measured is rotated at a constant speed by a spindle motor. The wrapping tape L is pressed onto the surface of the rotating magnetic disk medium 5 using the pad on the surface of the tape holder 18, and the spring pressure of the compression coil spring 20 is set in advance, so that the wrapping tape L is held at a constant pressure. Press against the magnetic disk medium surface. Since the position of the tape presser 18 is fixed, only a certain position 9 on the surface of the magnetic disk medium 5 is worn out in a perfect circle.

The wrapping tape passes between a motor-driven tape feed roller 16 and a pinch roller 21,
Since the tape is fed at a constant speed and wound onto the take-up roll 13, the wrapping tape L can always be worn on a new surface. Therefore, as long as the tape feeding speed is controlled to be constant, the wear conditions will always be constant.

Note that instead of using the compression coil spring 20, compressed air may be ejected from a nozzle and the tape tape L may be pressed against the surface of the magnetic disk medium using air pressure.

The wrapping tape is the same as that used for tape wrapping on the surface of magnetic disk media in the manufacturing process of magnetic disk media.
Hard particles such as iC or diamond are fixed to a film using a binder.

In this way, the fine particles of the abrasive of the lapping tape L are
Since the tape presser 18 presses the surface of the magnetic disk medium, the surface of the magnetic disk medium is quickly worn out and can be worn more efficiently in a shorter time than when using a core slider of a magnetic head.

When the surface of the magnetic disk medium wears out by sliding the wrapping tape L for a predetermined period of time, the rotation of the magnetic disk medium is stopped and the depth of wear of the worn portion 9 is measured. This measurement can be easily and accurately performed using a step measuring device, a fluorescent X-ray film thickness meter, etc., and the wear resistance can be quantitatively evaluated.

FIG. 3 is a diagram showing the results of abrading the magnetic disk medium surface with a lapping tape and measuring the abrasion depth with a fluorescent X-ray film thickness meter. The surface of the magnetic disk medium to be measured is covered with a carbon protective film, and the abrasive material is 3 μm.
A wrapping tape with a width of 12.7 mm to which fine alumina particles of 50 m are fixed is placed on a magnetic disk medium with a radius of approximately 441 m.
It was pressed against the position using compressed air pressure and rotated for 30 minutes.

Also, the rotational speed of the magnetic disk medium is 58 in terms of circumferential speed.
0m/min (250Orpm), compressed air flow rate is 4
51/min, wrapping tape feed speed 40mm/
min, and the wear depth after wear is set to 15+ when the spot diameter is 15+.
The thickness was measured using a fluorescent X-ray film thickness meter. The black circle is the measured value of the wear depth, and the film thickness on the worn part is thinner, and the difference from the film thickness on other non-worn surfaces (75 people) is the wear depth. Note that the white circle indicates the thickness of the carbon protective film before being abraded by the wrapping tape.

In this film thickness measurement, the detection diameter of fluorescent Nearby conditions are not accurately displayed. If you want to know the difference in level accurately, just calculate it based on the values in Figure 3 and the width of the wrapping tape. FIG. 4 shows the calculation results, where the white circles are actual measured values and the black circles are the calculation results (actual film thickness). As is clear from this calculation result, the carbon film is worn fairly uniformly in the area where the wrapping tape has slid.

FIG. 5 is a diagram showing the relationship between the sliding time of the wrapping tape and the abrasion depth, and shows the results of sliding the wrapping tape under the same conditions as in FIG. 3.

The black circle in the figure is a magnetic disk medium in which a magnetic film and a carbon protective film are laminated on a non-magnetic substrate surface that has been textured with fine lines in the circumferential direction. This is a magnetic disk medium in which a magnetic film and a carbon protective film are laminated on a magnetic substrate. In either case, the depth of wear increases in proportion to the sliding time.

Because the lapping chive L is fed out at a constant speed to constantly slide a new polished surface, the sliding conditions are always constant, and as a result, it is observed that the wear depth increases in proportion to the sliding time. .

According to the method of the present invention, the wear resistance of the magnetic disk medium surface can be measured accurately and quantitatively, so that the relationship between the sputtering conditions of the carbon protective film, the heat treatment conditions, and the wear depth, and the relationship between the sputtering power and the wear By measuring the relationship with depth, etc., it is also effective for determining optimal manufacturing conditions.

[Effects of the Invention] As described above, according to the present invention, a wrapping tape is brought into pressure contact with the surface of a magnetic disk medium rotating at a constant speed and slid, and the wear depth is measured after a predetermined period of time has elapsed. Therefore, a wear depth that can be easily measured can be obtained just by sliding for a short time, and wear resistance can be evaluated efficiently. In addition, since the wrapping tape is slid while being fed out, the sliding conditions are always constant.
Wear resistance can be measured and evaluated accurately and quantitatively.

[Brief explanation of the drawing]

FIG. 1 is a sectional view illustrating the basic principle of the method for evaluating wear resistance of a magnetic disk medium surface according to the present invention, FIG. 2 is a plan view and a sectional view illustrating a wrapping tape sliding device according to the present invention, and FIG. The figure shows the results of measuring the wear depth of the sliding part due to wrapping tape using fluorescent X-rays. Figure 4 shows the wear depth calculated from the same measurement results. Figure 5 shows the wear depth of the sliding part due to the wrapping tape. Figure 6 is a diagram showing the relationship between time and wear depth, Figure 6 is a diagram showing the laminated structure of a thin-film magnetic disk medium, and Figure 7 is a cross-sectional view illustrating a conventional method for evaluating the wear resistance of the surface of a magnetic disk medium. . In the figure, 1 is a non-magnetic substrate, 2 is a base film, 3 is a magnetic film, 4 is a protective film, 5 is a magnetic disk medium, 6 is a weight, 7 is a stylus, 8 is an interface, 9 is a sliding part, L is wrapping tape,
W is the pressing force of the wrapping tape, IO is the side plate, 11 is the feed roll, 13 is the take-up roll, 15 is the guide roller, 16 is the tape feed roller, M is the tape feed motor,
18 is a tape holder, 20 is a compression coil spring, and 21 is a pinch roller.

Claims (1)

[Claims] On the surface of a magnetic disk medium (5) rotating at a constant speed, a wrapping tape (L) is pressed and slid at a certain position with a certain pressure (W), and a certain period of time elapses. 1. A method for evaluating wear resistance of a magnetic disk medium surface, comprising: measuring the depth of a portion (9) of the surface of the magnetic disk medium slid by a wrapping tape (L).