JPH07318334A - X-ray analytical method and apparatus used for it - Google Patents

Abstract

PURPOSE:To provide an X-ray analytical method in which, when the film thickness of a film body composed of an organic substance such as a coating film formed on the surface of a substratum such as a steel plate is measured, the film thickness can be measured by using a common working curve which is not dependent on the kind of the film body and to provide an apparatus used for it. CONSTITUTION:A standard sample in which a film body 2 composed of an organic substance and having a known film thickness has been formed on the surface of a substratum such as a steel plate is irradiated with primary X-rays from an X-ray source 1, and a working curve indicating a correlation between the integrated value of the intensity of Compton scattering X-rays generated from the film body 2 and a film thickness is created. Then, the film body 2 as an object, to be analyzed, which is composed of the organic substance is irradiated with the primary X-rays from the X-ray source 1, the integrated value of the intensity of the Compton scattering X-rays generated from the film body 2 is applied to the working curve, and the film thickness of the film body 2 is found.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray analysis method for measuring the film thickness of a film made of an organic substance such as a coating film formed on the surface of a steel sheet, and an apparatus used therefor.

[0002]

2. Description of the Related Art Conventionally, the film thickness of a film made of an organic substance formed on the surface of a steel sheet has been measured by the following method.
First, the peak intensity of Compton scattered X-rays generated from a standard sample is irradiated by irradiating primary standard X-rays on a plurality of standard samples each of which is made of an organic substance and whose film thickness is known and whose film thickness is different from each other. Is detected and a calibration curve showing the correlation between the peak intensity of Compton scattered X-rays and the film thickness is prepared. next,
Irradiate the film to be analyzed made of organic matter with primary X-rays,
The peak intensity of Compton scattered X-rays generated from the film body is detected, and the peak intensity of the Compton scattered X-ray is applied to the calibration curve to obtain the film thickness of the film object to be analyzed.

[0003]

The correlation between the peak intensity of Compton scattered X-rays generated from a film made of an organic substance and the film thickness of the film varies depending on the type of the film. Therefore, in the conventional method, it is necessary to create a calibration curve for each type of film body, and for the film body of unknown type or a film body having a complicated structure such as a multilayer organic film, the measurement of the film thickness is performed. Was virtually impossible.

The present invention has been made in view of the above-mentioned conventional problems. When measuring the film thickness of a film body made of an organic substance, the film thickness is measured using a common calibration curve that does not depend on the type of the film body. It is an object of the present invention to provide an X-ray analysis method capable of measuring and an apparatus used therefor.

[0005]

Means and Actions for Solving the Problems In order to achieve the above object, as a result of research by the inventors, the integrated value of the intensity of Compton scattered X-rays generated from a film body made of an organic substance and the film thickness of the film body. It was found that the correlation with and does not depend on the variety of the membrane body, and the present invention has been completed. According to the method of claim 1, first, a standard sample provided with a film body made of an organic material and having a known film thickness is irradiated with primary X-rays, and the intensity of Compton scattered X-rays generated from the standard sample is detected. Next, a curve showing the change in the detected Compton scattering intensity with respect to the wavelength of the Compton scattered X-ray is obtained, and the integrated value with respect to the wavelength change of the curve is obtained. Then, a calibration curve showing the correlation between the integrated value and the film thickness is created.

The correlation between the integral value of the intensity of Compton scattered X-rays generated from a film made of an organic substance and the film thickness of the film is uniquely determined regardless of the kind of the film. Therefore, according to the method of claim 1, when measuring the film thickness of the film body made of an organic substance, it is possible to create a common calibration curve that does not depend on the type of the film body.

In the method of the second aspect, first, the film body made of an organic material is irradiated with primary X-rays, and the intensity of Compton scattered X-rays generated from the film body is detected. Next, a curve showing the change in the detected Compton scattering intensity with respect to the wavelength of the Compton scattered X-ray is obtained, and the integrated value with respect to the wavelength change of the curve is obtained. Then, the film thickness of the film body is obtained using the calibration curve prepared in claim 1.

According to the method of claim 2, when the film thickness of the film body made of an organic substance is measured, it is possible to measure the film thickness using a common calibration curve that does not depend on the type of film body.
Further, it is possible to measure the film thickness of a film body of unknown structure or a film body having a complicated structure such as a multilayer organic film.

The apparatus of claim 3 first comprises an X-ray source for irradiating a film made of an organic substance with primary X-rays, and an intensity detecting means for detecting the intensity of Compton scattered X-rays generated from the film. I have it. Further, it is provided with an intensity change detecting means for obtaining a curve showing a change in the detected Compton scattering intensity with respect to the wavelength of the Compton scattered X-ray, and an integral value calculating means for obtaining an integrated value with respect to the wavelength change of the curve.

According to the apparatus of claim 3, when the film thickness of the film body made of an organic substance is measured, a common calibration curve which does not depend on the type of the film body is prepared, and the film thickness is measured using the calibration curve. It becomes possible to measure the film thickness, and it becomes possible to measure the film thickness of a film body of an unknown product type or a film body having a complicated structure such as a multilayer organic film.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the apparatus of the present invention comprises a sample table 7 and
The sample S mounted thereon is provided with an X-ray source 1 for irradiating a primary X-ray Rh-Kα ray with a target of rhodium, for example. In this sample S, a film body 2 such as a coating film made of an organic material is formed on the surface of a base 20 such as a steel plate. This apparatus further comprises a dispersive crystal 8 for diffracting Compton scattered X-rays generated from the film body 2 at an angle θ, and Compton scattering X generated from the film body 2.
An intensity detecting means 3 for detecting the intensity of the line, an intensity change detecting means 4 for obtaining a curve showing a change in the detected Compton scattering intensity with respect to the wavelength of the Compton scattered X-ray, and an integral for obtaining an integrated value with respect to the wavelength change of the curve. Value calculation means 5
And output means 6 such as a printer for outputting the integrated value
Is equipped with.

[Method for Creating Calibration Curve] First, a method for creating a calibration curve using a standard sample will be described. In FIG. 1, a standard sample in which a film body 2 made of an organic material with a known film thickness is formed on the surface of a base 20 such as a steel plate is irradiated with primary X-rays from the X-ray source 1 to generate from the film body 2. The Compton scattered X-rays are diffracted by the dispersive crystal 8 at an angle θ, and the intensity of the Compton scattered X-rays generated from the film body 2 is detected by the intensity detecting means 3.
Detect with. The wavelength λ of the Compton scattered X-ray incident on the intensity detecting means 3 is obtained from the following equation. 2d sin θ = nλ d: surface spacing of the dispersive crystal 8 n: order of reflection (1, 2, 3, ...)

Here, if the dispersive crystal 8 is tilted by a certain angle with respect to the incident Compton scattered X-rays and the intensity detecting means 3 is tilted in the same direction by twice that angle, the angle is maintained while maintaining the diffraction phenomenon. θ can be changed. That is, it is possible to measure the wavelength λ of the Compton scattered X-ray incident on the intensity detecting means 3 while changing the wavelength λ thereof. At the same time, since the intensity is detected by the intensity detecting means 3, a curve showing a change in the intensity of the Compton scattered X-rays with respect to the wavelength of the Compton scattered X-rays as shown in FIG. 2 is detected by the intensity change detecting means 4 (FIG. 1). You can ask.
At this time, for example, when the type of the film body 2 is polyimide PI, the curve A shown by the solid line in FIG.
When it is P, a curve B shown by a broken line is obtained.

Here, conventionally, since the amount of energy lost when the primary X-rays are changed to Compton scattered X-rays differs depending on the constituent elements of the film body 2, the film body 2 in FIG.
It was known that the wavelength showing the peak intensity of Compton scattered X-rays varies depending on the product type, for example, λ _A for polyimide PI and λ _B for polypropylene PP are different, but the shape of the curve should be considered. Instead, a calibration curve showing the correlation between the peak intensity of Compton scattered X-rays and the film thickness was prepared as shown in FIG. However, since the correlation between the peak intensity of Compton scattered X-rays generated from the film body 2 made of an organic substance and the film thickness of the film body 2 differs depending on the type of the film body 2, in the conventional method, for example, in FIG. It was necessary to prepare a calibration curve for each product type such as a calibration curve for polyimide PI indicated by a solid line, a calibration curve for polypropylene PP indicated by a broken line, and a calibration curve for polyester PE indicated by a two-dot chain line.

On the other hand, in the present invention, in FIG. 2, the shape of the curve changes depending on the type of the film body 2, for example, the shape of curve A for polyimide PI and the shape of curve B for polypropylene PP are different. Focusing on the above, the integrated value of the intensity of Compton scattered X-rays is obtained by the integrated value calculating means 5 (FIG. 1), output by the output means 6 (FIG. 1), and the correlation between this integrated value and the film thickness is shown in FIG. It was decided to create a calibration curve like this.

Compton scattering X by the integral value calculating means 5
Regarding the calculation of the integrated value of the intensity of the line, there is a method of approximating the curve of FIG. 2 by a Gaussian distribution or a Lorentz distribution to calculate the area under the curve, but in this embodiment, the following simple method is used. It depends on the method. Taking the case where the type of the standard sample is polyimide PI, that is, the case of the curve A as an example, first, an appropriate wavelength width λ ₀ (eg, from the wavelength λ _A showing the peak intensity I _A of Compton scattered X-rays) to the left and right (for example, The diffraction angle θ
Then, the wavelength shifted by (wavelength width corresponding to 0.5 degree),
That is, points P ₂ and P ₃ on the curve A at the wavelength λ _A −λ ₀ and the wavelength λ _A + λ ₀ are obtained, and these points and the peak point P ₁ on the curve A indicating the peak intensity I _A of the Compton scattered X-ray. The shape of the curve A is approximated by two straight lines P ₁ P ₅ and P ₁ P ₆ (shown by a chain line in FIG. 2) passing through.

Next, the two straight lines P ₁ P ₅ , P ₁ P ₆ and
In FIG. 2, the width λ _S at the half value I _A / 2 of the peak intensity I _A of the Compton scattered X-rays is calculated in the triangle P ₁ P ₅ P ₆ defined by the horizontal axis indicating the intensity of the Compton scattered X-rays is 0. , I _A × λ _{S, the} triangle P ₁ calculated from
The area of curve A below point P ₁ is approximated by the area of P ₅ P ₆ . When the peak intensity of the Compton scattered X-ray have multiple, for example, when in addition to the peak intensity I _C of the peak intensity I _A is present in the curve A, calculated similarly to the from the wavelength lambda _C indicative thereof and the peak intensity I _C The area of the curved line A below the peak point P ₄ is approximated by the area of the triangle. Then, the sum of the areas of the triangles calculated in this way is set as the integrated value of the intensity of Compton scattered X-rays.

This integral value is obtained for a plurality of standard samples whose film thickness of the film body 2 is known and whose film thicknesses are different from each other, and the integration of the intensity of Compton scattered X-rays as shown in FIG. A calibration curve showing the correlation between the value and the film thickness is created. The calibration curve actually created in this way was the same even if the type of the membrane body 2 was different.

[Method for Measuring Film Thickness of Sample to be Analyzed] Next, a method for measuring the film thickness of the film body to be analyzed using the calibration curve will be described. The X-ray source 1 of FIG. 1 irradiates the film body 2 made of an organic substance to be analyzed with primary X-rays, and the intensity of the Compton scattered X-rays generated from the film body 2 is detected by the intensity detecting means 3. Subsequently, as in the case of creating the calibration curve, a curve showing a change in the intensity of the Compton scattered X-ray with respect to the wavelength of the Compton scattered X-ray as shown in FIG. 2 is obtained by the intensity change detection means 4 (FIG. 1), The integrated value of the intensity of Compton scattered X-rays is obtained by the integrated value calculation means 5 (FIG. 1), and output means 6
(Fig. 1). Then, the integrated value is applied to the calibration curve to obtain the film thickness of the film body 2.

[0020]

As described above, in the case of measuring the film thickness of a film body made of an organic substance, according to the present invention, a common calibration curve which does not depend on the type of the film body is prepared and the calibration curve is prepared. Since it is possible to measure the film thickness of various types of film bodies using the line, the measurement efficiency is improved. Further, it is possible to measure the film thickness of a film body of a complicated structure such as a film body of which the product type is unknown or a multi-layer organic film, so that the applicable range of the measurement is expanded.

[Brief description of drawings]

FIG. 1 is a schematic side view showing a configuration of the present invention.

FIG. 2 is a diagram showing a curve showing changes in the intensity of Compton scattered X-rays with respect to the wavelength of Compton scattered X-rays in the present invention.

FIG. 3 is a calibration curve showing the correlation between the integral value of the intensity of Compton scattered X-rays and the film thickness in the present invention.

FIG. 4 is a calibration curve showing the correlation between the peak intensity of conventional Compton scattered X-rays and the film thickness.

[Explanation of symbols]

1 ... X-ray source, 2 ... Film body, 3 ... Intensity detecting means, 4 ... Intensity change detecting means, 5 ... Integral value calculating means.

Claims (3)

[Claims] 1. A standard sample provided with a film body made of an organic material and having a known film thickness is irradiated with primary X-rays, and the intensity of Compton scattered X-rays generated from the standard sample is detected. Obtaining a curve showing the change in the detected Compton scattering intensity with respect to the wavelength, obtaining an integral value with respect to the wavelength change of the curve, and obtaining a calibration curve showing the correlation between the integral value and the film thickness Creation of a calibration curve in X-ray analysis Method. 2. A film body made of an organic material is irradiated with primary X-rays, the intensity of Compton scattered X-rays generated from the film body is detected, and the change in the detected Compton scattered intensity with respect to the wavelength of the Compton scattered X-rays. A film thickness measuring method by X-ray analysis for obtaining a film thickness of the film body by using the calibration curve prepared in claim 1 to obtain an integrated value with respect to a wavelength change of the curve. 3. A measuring device for measuring the film thickness of a film body made of an organic substance by using Compton scattered X-rays, comprising: an X-ray source for irradiating the film body with primary X-rays; Intensity detecting means for detecting the intensity of the generated Compton scattered X-rays, intensity change detecting means for obtaining a curve showing a change in the detected Compton scattered intensity with respect to the wavelength of the Compton scattered X-rays, and an integral value with respect to the wavelength change of the curve. An apparatus for measuring film thickness by X-ray analysis, comprising: