KR102433027B1 - Colloidal film surface evaluation method and apparatus - Google Patents

Abstract

The present invention discloses a method and apparatus for evaluating the surface of a colloidal film. According to the present invention, it comprises a processor and a memory connected to the processor, wherein the memory receives an optical microscope image of a surface of a colloidal film coated with colloidal particles on a substrate, and from the optical microscope image of the colloidal particles Counting the total number of particles N, generating a position matrix for the plane coordinates of the counted N colloidal particles, and using the position matrix N using the plane coordinates of each particle as a reference point for the N colloidal particles To generate four Voronoi polygons, calculate the planar filling ratio using the area of each of the N Voronoi polygons and the cross-sectional area of the colloidal particle, and quantify the defect level of the colloidal film surface using the calculated planar filling ratio , an apparatus for evaluating the surface of a colloidal film for storing program instructions executable by the processor is provided.

Description

Colloidal film surface evaluation method and apparatus

The present invention relates to a method and apparatus for evaluating the surface of a colloidal film, and more particularly, to a method and apparatus for evaluating the surface density and uniformity of a colloidal film produced by applying a colloidal dispersion on a substrate.

With the recent development of the materials industry and the movement of miniaturization and advancement of products, the level of demand for films having specific functions and precision required for materials is increasing significantly.

Accordingly, it is very important to manage the uniform coating properties of the particles on the surface, especially in the case of a large-area coating including functional particles.

For example, in the case of a photonic crystal using colloidal crystallization, a catalyst filter for automobiles, and an antireflection film, minimizing defects in the middle of the film is directly related to product quality and productivity.

In order to manage these defects, it is necessary to establish a database through defect detection, statistical average, and quantified data accumulation.

The uniformity evaluation of a slurry composed of spherical colloidal particles is usually performed by checking the viscosity ratio at a specific shear rate obtained from a viscometer in the slurry stage, or indirectly calculating the volumetric porosity by making a dry film and measuring the dry film density using the Archimedes method. done in a way

However, the conventional methods do not evaluate the colloidal film as a product, but rather reflect only the material properties of the slurry, which is the raw material. However, there is a problem in that it does not provide accurate information about the non-uniformity that occurs during the drying process.

Korean Patent Registration Publication No. 10-2150209

In order to solve the problems of the prior art, the present invention is to propose a method and apparatus for evaluating the surface of a colloidal film capable of quantifying the defects of the colloidal film.

According to a preferred embodiment of the present invention in order to solve the problems of the prior art, as an apparatus for evaluating the surface of a colloidal film, a processor; and a memory connected to the processor, wherein the memory receives an optical microscope image of a surface of a colloidal film coated with colloidal particles on a substrate, and the total number of colloidal particles N from the optical microscope image Counting, generating a position matrix for the plane coordinates of the counted N colloidal particles, and using the position matrix to generate N Voronoi polygons using the plane coordinates of each particle as a reference point for the N colloidal particles and calculating the planar filling factor using the area of each of the N Voronoi polygons and the cross-sectional area of the colloidal particles, and quantifying the defect level on the surface of the colloidal film using the calculated planar filling ratio, executed by the processor A device for evaluating the surface of a colloidal film that stores possible program instructions is provided.

A plurality of the optical microscope images may be acquired at different positions of the colloidal film, and the program instructions may independently calculate a planar filling factor for the plurality of optical microscope images.

The program instructions calculate the average value and the dispersion value of the plane fill factor obtained from each of the plurality of optical microscope images, and compare the calculated average value and the dispersion value with a reference sample stored in advance to evaluate the defect level of the surface of the colloidal film. have.

The average value may be an ensemble average of plane filling rates of each of the colloidal particles included in the plurality of optical microscope images.

The dispersion value may be determined by the following equation.

[Equation]

는 평면충진율이고, < >는 앙상블 평균임here,

is the flat fill factor, and <> is the ensemble average

Quantifying the level of defects on the surface of the colloidal film can quantify the density and uniformity of colloidal positions on the surface of the colloidal film.

The cross-sectional area of the colloidal particles may be calculated from an average radius of the colloidal particles input in advance.

According to another aspect of the present invention, there is provided a method for evaluating a colloidal film surface in a device including a processor and a memory, the method comprising: receiving an optical microscope image of a colloidal film surface coated with colloidal particles on a substrate; counting the total number of particles N of the colloidal particles from the optical microscope image; generating a position matrix for the plane coordinates of the counted N colloidal particles; generating N Voronoi polygons using the plane coordinates of each particle as a reference point for the N colloidal particles using the position matrix; calculating a planar filling factor using the area of each of the N Voronoi polygons and the cross-sectional area of the colloidal particle; and quantifying the level of defects on the surface of the colloidal film by using the calculated planar filling factor is provided.

According to another aspect of the present invention, there is provided a computer readable program for performing the above method.

According to the present invention, there is an advantage in that the density and uniformity of the film can be evaluated from the particle distribution on the surface (top layer) of the film composed of colloidal particles after drying, which is relatively easy to observe using an optical microscope.

1 is a diagram illustrating a process for evaluating a colloidal film using an optical microscope image according to a preferred embodiment of the present invention.
2 is a view illustrating an optical image obtained in the drying process of spherical polystyrene particles having a diameter of 1 μm.
3 is a view showing a film surface having different distributions of particles obtained by visualizing the optical microscope image according to the present embodiment through a computer.
4 shows a Voronoi polygon generated from the colloidal particle distribution of FIG. 3 .
5 shows (a) the average value of Sf and (b) the dispersion value of Sf in each condition.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail.

However, this is not intended to limit the present invention to specific embodiments, and it should be understood that all modifications, equivalents and substitutes included in the spirit and scope of the present invention are included.

Hereinafter, it will be described in detail with reference to embodiments according to the present invention.

The present invention is to suggest a method for evaluating the density and uniformity of a colloidal film from the particle distribution on the surface of the film composed of colloidal particles after drying, which is relatively easy to observe using an optical microscope.

1 is a diagram illustrating an evaluation process of a colloidal film using an optical microscope image according to a preferred embodiment of the present invention.

The process of FIG. 1 is performed in a colloidal film surface evaluation apparatus including a processor and a memory.

Here, the processor may include a central processing unit (CPU) capable of executing a computer program or other virtual machines.

The memory may include a non-volatile storage device such as a fixed hard drive or a removable storage device. The removable storage device may include a compact flash unit, a USB memory stick, and the like. The memory may also include volatile memory, such as various random access memories.

Such memory stores program instructions executable by the processor.

The program instructions according to an embodiment of the present invention evaluate the surface of the colloidal film after drying by performing the process shown in FIG. 1 .

Hereinafter, the process of performing the colloidal film surface evaluation apparatus according to the present embodiment will be described in detail.

Referring to FIG. 1 , the colloidal film surface evaluation apparatus receives an optical microscope image of the surface of the colloidal film (step 100 ).

The colloidal film of step 100 is a film completed until drying by applying a colloidal dispersion on a substrate.

2 is a view illustrating an optical image obtained in a drying process of spherical polystyrene particles having a diameter of 1 μm. Here, the scale bar is 10 μm.

In addition, the average radius of the colloidal particles is input in advance to the colloidal film surface evaluation device (step 102).

The average particle diameter of the particles included in the colloidal dispersion can be obtained in advance using a general particle size measuring device, and 1/2 of the average particle diameter is taken as the average radius (a).

Next, the total number of colloidal particles (N) is counted from the optical microscope image obtained in step 100 (step 104), and a position matrix is generated for the plane coordinates (two-dimensional plane position information) of all colloidal particles on the surface ( step 106).

Referring to FIG. 2 , a point that appears relatively bright in the optical microscope image is the position of the central point of the particle, and by counting it, it is possible to obtain the plane coordinates of the particle existing within a certain area.

In step 104, one optical microscope image may be divided into a plurality of sets, the total number of particles (N) is the number of particles included in each set, and the colloidal film evaluation apparatus according to this embodiment is Repeat the process below for

That is, a plurality of optical microscope images can be obtained for different points of the colloidal film, each optical microscope image constitutes one set, and the calculation of planar filling factor, average value and dispersion value described below for the plurality of sets The process may be performed.

In addition, coordinates for N particles may be generated and stored as a quadratic matrix of N×N.

3 is a view showing a film surface having different distributions of particles obtained by visualizing the optical microscope image according to the present embodiment through a computer.

3 is an image of 1 μm particles obtained in a square size of 16 μm x 16 μm, FIG. 3a is condition I, FIG. 3b is condition II (10% defect), and FIG. 3c is condition III (20% defect).

Here, x corresponds to the horizontal axis and z corresponds to the vertical axis on the plane. The y-axis not shown here corresponds to the height direction.

The apparatus according to the present embodiment generates a plurality of Voronoi polygons using the plane coordinates of each particle as a reference point by using the position matrix (step 108).

Voronoi diagram means that when several points are distributed on a plane, the closest points are judged from each point, and lines are created that spatially divide the midpoints between the points. are called polygons.

4 shows different Voronoi polygons generated from the colloidal particle distribution of FIG. 3 .

Using the Voronoi polygon generated in step 108, it is possible to know the space occupied by arbitrary colloidal particles.

Next, the device according to the present embodiment calculates the area of the polygon surrounding the individual colloidal particles (step 110).

In operation 110, Voronoi polygonal areas for each of the N particles may be calculated.

After the Voronoi polygonal area is calculated, the device according to the present embodiment calculates the planar filling factor by using the ratio of the individual polygonal area to the cross-sectional area of the colloidal particle (step 112).

The cross-sectional area of the layered spherical particles can be simplified to the area of a circle. When the radius of the spherical particle is a, the cross-sectional area of the spherical particle is πa ² .

When the polygonal area surrounding one particle is A _polygon , the planar filling factor is obtained from Equation 1 below.

Steps 104-112 described above are iteratively calculated for all particles in the sampled set (step 114).

)과 산포값(

)을 계산한다(단계 116).After the planar filling factor of each particle in all sets is calculated, the device according to this embodiment calculates the average value (

) and the variance (

) is calculated (step 116).

Here, < > means ensemble average.

According to a preferred embodiment of the present invention, when the average value and the dispersion value calculated in step 116 are used, the level of occurrence of defects and the uniformity and density of the colloidal film can be evaluated.

The evaluation of the level of defect occurrence can be performed through the process of comparing the colloidal film currently obtained with a reference sample.

Hereinafter, a process of evaluating a colloidal film coated with polystyrene colloidal spherical particles having an average particle diameter of 1 μm will be described in detail through an experimental process.

Example

Evaluation was carried out on a solution in which polystyrene colloidal spherical particles (a=0.5 μm) having an average particle diameter of 1 μm were dispersed.

After dropping a few drops of the colloidal dispersion on a slide glass, use a coater with a blade at a certain height to make the liquid level uniform, and then dry it.

The drying speed is controlled by changing the humidity inside the experimental device. The film thickness and drying rate in the experiment were as follows. The initial height in the wet film state was made to be the same as 60 μm, and the drying rate was adjusted so that the decrease rate of the film height was 2.2 μm/sec.

The optical microscope image was measured with a micros MC500 model. A set of 10 samples including particles existing within an arbitrary area of 16 μm×16 μm as one set can be obtained, one of which is illustrated in FIG. 3( a ).

In order to quantify the effect of surface density by way of example, data were generated that generated 10% and 20% of surface defects, respectively, compared to Fig. 3a, which is a sample made relatively uniformly, and one of the images was assigned a 10% defect (Fig. 3b). ) and 20% defect (Fig. 3c).

Here, the data with defects was generated by randomly removing random particles from the original data. That is, assuming that the total number of particles in one original image set is 262, a 10% defect corresponds to a set with 210 particles with 26 erased from the original, 236 particles with a 20% defect, and 210 particles with 52 erased from the original image set. do. The results obtained under each condition are shown in FIG. 5 and Table 1.

5 shows (a) the average value of Sf and (b) the dispersion value of Sf in each condition.

Here, the size of the error bar represents a standard deviation value existing between 10 sampled sets.

Condition I II III Relative defect (%) 0 10 20 Average value of flat fill factor 0.80 0.74 0.67 Planar filling factor dispersion value 0.0042 0.014 0.023

Finally, it is confirmed that the average value and dispersion value of the obtained planar filling factor well reflect the linearly increased defect. Compared to condition I, which is the reference condition, with respect to the increase in defect, the average value of the fill rate is linearly decreasing and the dispersion value of the fill rate is increasing linearly, so it is confirmed that the evaluation method using the Voronoi diagram is sufficient to quantify the defect level do.

The above-described embodiments of the present invention have been disclosed for the purpose of illustration, and various modifications, changes, and additions will be possible within the spirit and scope of the present invention by those skilled in the art having ordinary knowledge of the present invention, and such modifications, changes and additions should be regarded as belonging to the following claims.

Claims (10)

A colloidal film surface evaluation device, comprising:
processor; and
a memory coupled to the processor;
The memory is
Colloidal particles receive an optical microscope image of the surface of the colloidal film coated on the substrate,
Counting the total number of particles N of the colloidal particles from the optical microscope image,
generating a position matrix for the plane coordinates of the counted N colloidal particles,
Generate N Voronoi polygons using the plane coordinates of each particle as a reference point for the N colloidal particles using the position matrix,
Calculate the planar filling factor using the area of each of the N Voronoi polygons and the cross-sectional area of the colloidal particle,
To quantify the level of defects on the surface of the colloidal film using the calculated planar filling factor,
A colloidal film surface evaluation device storing program instructions executable by the processor. According to claim 1,
The optical microscope image is acquired in plurality at different positions of the colloidal film,
The program instructions are
An evaluation device for the surface of a colloidal film that independently calculates the planar filling factor for a plurality of optical microscope images. 3. The method of claim 2,
The program instructions are
Calculate the average value and the dispersion value of the plane filling factor obtained from each of the plurality of optical microscope images,
A colloidal film surface evaluation apparatus for evaluating the defect level of the colloidal film surface by comparing the calculated average value and the dispersion value with a reference sample stored in advance. 4. The method of claim 3,
The average value is a colloidal film surface evaluation device that is an ensemble average of planar filling rates of each colloidal particle included in the plurality of optical microscope images. 5. The method of claim 4,
The dispersion value is a colloidal film surface evaluation device determined by the following equation.
[Equation]

here,

is the flat fill factor, and <> is the ensemble average According to claim 1,
Quantifying the level of defects on the surface of the colloidal film is an evaluation device for the surface of a colloidal film, defined as quantifying the density and uniformity of colloidal positions on the surface of the colloidal film. According to claim 1,
The cross-sectional area of the colloidal particles is a colloidal film surface evaluation device that is calculated from the average radius of the colloidal particles input in advance. A method for evaluating a colloidal film surface in a device comprising a processor and a memory, the method comprising:
receiving an optical microscope image of a colloidal film surface coated with colloidal particles on a substrate;
counting the total number of particles N of the colloidal particles from the optical microscope image;
generating a position matrix for the plane coordinates of the counted N colloidal particles;
generating N Voronoi polygons using the plane coordinates of each particle as a reference point for the N colloidal particles by using the position matrix;
calculating a planar filling factor using the area of each of the N Voronoi polygons and the cross-sectional area of the colloidal particle; and
A method for evaluating the surface of a colloidal film comprising the step of quantifying the level of defects on the surface of the colloidal film using the calculated planar filling rate. 9. The method of claim 8,
The optical microscope image is acquired in plurality at different positions of the colloidal film,
The plane filling factor calculation step independently calculates the plane filling factor for a plurality of optical microscope images,
After the plane filling factor calculation step,
calculating an average value and a dispersion value of the planar filling factor obtained from each of the plurality of optical microscope images; and
The evaluation method of the colloidal film surface further comprising the step of comparing the calculated average value and the dispersion value with a reference sample stored in advance.


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