JPS60128306A - Lubricant film thickness measuring method of magnetic disk medium - Google Patents

Abstract

PURPOSE:To derive easily and exactly a lubricant film thickness in a short time by irradiating X rays of a specified frequency to the surface, and measuring the lubricant film thickness basing on a signal area ratio regarding an intensity of an emitted photoelectron. CONSTITUTION:Both faces of a bustrate 1 are covered with a magnetic material layer 2, and the magnetic material layer 2 is protected by a lubricant holding layer 3 consisting of an inorganic silicon compound whose main component is SiO2, and a lubricant film 4. When this magnetic disk medium is cut to small pieces and irradiated under a high vacuum, a photoelectron jumps out with a constant kinetic energy at every constituent element. A binding energy of oxygen O1s of polyether fluoride being a material quality of the lubricant film 4 is a signal having a peak in the vicinity of 537.1eV, and a peak of a signal of an inorganic silicon compound being a material quality of the lubricant holding layer 3 is in the vicinity of 534.2eV. A lubricant film thickness is measured basing on an area ratio of these two signals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for measuring the film thickness of a lubricant coated on the surface of a magnetic disk medium.

[Prior art]

Generally, a lubricant such as silicone oil or fluorinated oil is applied to the surface of a magnetic disk medium. This is to reduce friction and wear when the magnetic disk medium starts rotating, stops rotating, and rotates at a constant speed, and to provide sufficient durability for long-term operation.

Methods for applying lubricant include dipping in a lubricant solution tank and spraying of lubricant solution.

There are spin code methods, etc. When using these methods, it is necessary to set the film thickness to an optimum value in order to ensure sufficiently high reliability for long-term operation of the magnetic disk. For this reason, it is essential to control the lubricant concentration in the lubricant solution. In addition, it is necessary to smooth the lubricant by heat sag on the magnetic disk medium after coating and to apply high temperature 1 to form an appropriate lubricant layer. It is necessary to wipe it off using a rotating pad with degreased paper.

However, since the lubricant film thickness is extremely thin, ranging from 0 to several 10,000 ml, there is no suitable measuring method, and the selected lubricant concentration and treatment method cannot provide the optimal lubricant film thickness. It was not possible to judge whether or not the film was coated with a stable film thickness. Therefore, the lubricant concentration and the method of processing the magnetic disk after applying the lubricant were determined empirically, and the magnetic disk medium? The production yield 9 was low, and the adhesion between the magnetic disk and the magnetic head could not be sufficiently prevented due to wear and tear during operation of the magnetic disk medium, 9TI-f5, etc.

[Summary of the invention]

The present invention has been made in view of the above-mentioned problems.The purpose of the present invention is to provide a new method for measuring the film thickness of a lubricant applied to the surface of a magnetic disk medium with high accuracy and ease. The purpose is to provide a method. □ In order to achieve this purpose, we developed a method that applies X-ray photoelectron spectroscopy, which is already known as a method for analyzing the composition of materials. This method involves emitting photoelectrons by irradiating the surface of the medium with X-rays of a specific frequency, and measuring the lubricant film thickness based on the signal area ratio of the intensity of the emitted photoelectrons. The present invention will be described in detail together with examples.

Figure $1 is a sectional view of a magnetic disk medium in an embodiment of the present invention. 1 is a substrate υ, both sides of which are coated with magnetic layers 2; Reference numeral 3 denotes a lubricant holding layer made of an inorganic silicon compound containing 5102 as a main component, and has the role of holding a lubricant [114, which will be described later], and protecting the magnetic layer 2. 4 is a lubricant film made of fluorinated polyether, which is coated with the lubricant holding layer 3 by a spin cord method, a spray method, a dipping method, or the like. In addition, this lubricant film 4 has an extremely thin film thickness of several tens of peaks or less, and a magnetic disk medium with such a structure is first coated with 611 to LogiL.
Cut into small pieces of corners, and
Installed in the beam irradiation sample room. Then, when X-rays of a specific wavelength are irradiated onto the magnetic disk piece under high vacuum, photoelectrons are ejected from each constituent fiber with a certain kinetic energy. X
Line photoelectron spectroscopy measures the intensity of these photoelectrons. In this ζ, the ratio of the kinetic energy of the irradiated X-rays and electrons is called the bond energy, and this value ← is a value that reflects the bonding mode of the constituent elements of the sample. Note that the purpose of cutting the magnetic disk medium into small pieces is simply to match the size of the sample chamber of the X-ray photoelectron spectrometer, and if the chamber is sufficiently large, cutting is not necessary.

FIG. 2 is a diagram showing the state of photoelectrons emitted by irradiating X-rays onto the surface of the hazy disk. Production disk medium surface characteristics X@1. When irradiated with photoelectronic chips 1 and 1. from the lubricant film 4 and lubricant holding layer 3, is emitted-
I know it will happen.

□1 Here, since the lubricant film 4 is made of fluorinated polyether and the lubricant holding s3 is made of an inorganic silicon compound whose main component is S10□, oxygen is an element common to both.

Figure 3 shows 0.0% of the oxygen atom. ．． 2 is a graph showing X@photoelectron spectroscopy signals from the lubricant film 4 and the lubricant holding layer 3. In the figure, the vertical direction is the intensity of photoelectrons. 7, which is the material of the lubricant film 4, oxygen 0111 of tsunated polyether
The binding energy of the signal is a signal having a peak around 537.1 sV, which is around the peak #15342 eV of the digol of the inorganic silicon compound which is the material of the lubricant holding layer 3. The difference between these two peaks is about 2.9 ev. Third. Figure h) When the lubricant film 4 of Fi fluorinated polyether is thin, and therefore the signal of the inorganic pyricone compound of 5342 V is larger than the signal of the 7-wire polyneedle of 537.1 V. Deru, lubricant film 4
Because of the thickness of 537,↓·V, the signal of the fluorinated polyether is larger than the signal of the inorganic silicon compound of 5342*V. Since there is a difference in binding energy between the 011 signal peak of the fluorinated polyether and the 011 signal peak of the inorganic silicon compound, as explained below, highly accurate waveform analysis of each component is required. It is possible. 4 is a waveform analysis diagram of the olm signal of oxygen atoms in the magnetic disk medium, which is approximated by a Gaussian waveform for each component. In this ζ, Sl is oll of fluorinated polyether
The signal area approximated by a Gaussian waveform of I is the signal area approximated by a Gaussian waveform of Oi- of the inorganic silicon compound, and S is the signal area approximated by a Gaussian waveform of Oi- of the inorganic silicon compound. Note that a mixed waveform of a Gaussian waveform and a Lorentzian waveform among the Lorentzian waveforms can be used as appropriate for waveform approximation. The solid line is the original waveform, the nine-dot line is the approximated Gaussian waveform of the fluorinated polyether and the inorganic silicon compound, and the one-dot chain line is the combined waveform. Through a waveform analysis such as this, it was found that the relationship between the 01s signal area ratio (that is, the value of 8 v' Sm) and the film thickness of the lubricant film 4 made of fluorinated polyether is a logarithmic relationship such as an expansion order. I understand. That is, assuming that the thickness a (i) of the fluorinated polyether layer is the thickness a (i), it can be obtained from the analysis that the following equation (1) holds true.

Here, m1em* is a constant.

In addition, (1) formula can be determined as follows = intensity of photoelectron peak of fluorinated polyether! 1 is the I of the underlying inorganic silicon compound layer measured through a fluorinated polyether film of thickness dl.

(3).

Here, C: Sensitivity of the measurement system to photoelectrons with proportionality constant IO = Oi X-ray intensity @2 kinetic energy E (
Detection efficiency) σl: Photoionization cross section of the atom of interest in the first layer nl: Atomic number density of the atom of interest in the first layer λ1 @: Escape depth dl of photoelectrons with kinetic energy E into the first layer: The thickness β of the first layer is the escape angle of photoelectrons incident on the analyzer (here, β#o). 1 (4) When the energy values of the photoelectron peaks of interest are approximately equal, the butterfly detection efficiency can be approximated to be equal.

Therefore, e(It) = e(Is) Also, since El and E3 are equal, λ104) = λt(Es) → λ.

Let 2m (Ex) = λ * (Iiis) → λ mushroom.

Therefore, equation (4) is expand it becomes.

Here, 01=σ8, and known literature (0M,
P, Be&h And W A, DencN, 5ur
f, InterfaceAnlLA, Vo41.
P, 2 (1979) and ■R, Ftltsehan
d8.1. R&ld*r, J, Vac, Sc
i, Tachno4, Vo412 style LP, 30
5 (1975)), λ1 #16 A + λ2
#18±5A. If m2 is a constant, n! //n
1=m.

becomes.

becomes.

becomes.

Since dl is the same as d, equation (8) is equivalent to equation (1).

FIG. 5 is a diagram showing the relationship between the fluorinated polyether film thickness determined from equation (1) and the signal area ratio of 018 from the fluorinated polyether and the inorganic silicon compound by X-ray photoelectron spectroscopy. As can be seen from this figure, X-ray photoelectron spectroscopy of a part of the surface of a magnetic disk medium in which a fluorinated polyether film was formed on an inorganic silicon compound revealed that fluorinated polyether of oxygen 0111 and inorganic silicon By measuring the area ratio of the signal of the compound, the thickness of the fluorinated polyether film can be easily and accurately determined in a short time from the formula (1) to FIG.

In this example, fluorinated polyether is used as the lubricant, and an inorganic silicon compound containing StO as the main component is used as the lubricant holding layer, so oxygen is listed as a common constituent element. It goes without saying that the film thickness of the lubricant can be similarly measured from the intensity of the photoelectrons, depending on the material used for these materials, such as silicon or carbon.

〔Effect of the invention〕

As explained above, the present invention irradiates the surface of a magnetic disk medium coated with a predetermined lubricant with X-rays of a specific frequency to emit photoelectrons, and the signal area ratio of the intensity of the emitted photoelectrons. Since the lubricant film thickness is measured based on , the lubricant film thickness can be determined easily and accurately in a short time.

Therefore, the lubricant film thickness can be controlled accurately and precisely, and the friction between the magnetic disk and the magnetic head can be reduced to minimize the amount of wear. This makes it possible to prevent undesirable phenomena for the head.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a magnetic disk medium in an embodiment of the present invention, Fig. 2 is a diagram showing the state when the surface of the 4-inch disk medium is irradiated with X-rays, and Fig. 3 is a signal of the company's X-ray photoelectron spectroscopy. FIG. 4 is a diagram showing a waveform analysis using a Gaussian waveform of the signal of X-ray photoelectron spectroscopy, and FIG. 5 is a diagram showing the relationship between the fluorinated polyether film thickness and the signal area ratio by X-ray photoelectron spectroscopy. . DESCRIPTION OF SYMBOLS 1-... Substrate, 2... ψ magnetic layer, 3... Lubricant holding layer, 4... Lubricant film. Patent Applicant: Nippon Telegraph and Telephone Public Corporation Agent Masaki Yamakawa Figure 1 Figure 2

Claims (1)

[Claims] A lubricant retaining layer is formed on a magnetic layer, and a lubricant containing the same constituent atoms as the lubricant retaining layer is coated on the surface of the magnetic disk medium.
emitting photoelectrons from the lubricant-retaining layer and the lubricant, and measuring the film thickness of the lubricant based on the signal area ratio of the intensity of the emitted photoelectrons; Features: A method for measuring lubricant film thickness on magnetic disk media.