KR20220064506A - Precise Measurement Device of the Dielectric Constants of Solid Dielectrics - Google Patents

Abstract

The present invention relates to an apparatus for precisely measuring a dielectric constant of a solid dielectric, capable of minimizing measurement errors by using cross capacitance principles. In accordance with the present invention, the apparatus for precisely measuring a dielectric constant of a solid dielectric comprises: an internal electrode; an external electrode surrounding an outer circumference surface (outer curved surface) of the internal electrode evenly with a tiny gap; a shielding case shielding an outer circumference surface (outer curved surface) of the external electrode by surrounding the outer circumference surface evenly with a tiny gap while insulating the external electrode; and an insulator provided inside the shielding case to electrically insulate the internal and external electrodes while maintaining the tiny gap evenly between the internal and external electrodes. Therefore, the apparatus has an electrode structure comprising four main electrodes, and comprises one pair of electrode parts placed to be vertically symmetrical to each other.

Description

Precise Measurement Device of the Dielectric Constants of Solid Dielectrics

The present invention relates to an apparatus for precisely measuring the dielectric constant of a solid dielectric using a cross capacitance principle, and more particularly, to an apparatus for accurately measuring the dielectric constant of a solid dielectric that minimizes measurement errors with high accuracy.

Dielectrics are widely used in communications, antenna housings, power generation, frequency standards, semiconductors, and the like.

Dielectrics used in products and parts for electronic devices, or various communication devices and semiconductors in the recent miniaturization and high frequency trend, must have strict dielectric properties to support the increase in communication volume and information transmission speed. A technique that can measure accurately is absolutely necessary.

In addition, it is necessary to establish precise measurement technology for accurate dielectric properties to determine the performance of the standard reference material (CRM) used for verification and certification of measurement uncertainty for the measurement results of dielectric properties measuring equipment.

As factors that determine the electrical properties of a dielectric, there are volume resistivity, surface resistivity, dielectric constant (or dielectric constant), loss factor (or loss angle), and dielectric strength. In particular, relative dielectric constant (or dielectric constant) and loss factor (or loss angle) are measured and utilized as important characteristics.

Until now, the three-terminal guard-ring electrode method using two parallel plate electrodes, the two-terminal micrometer electrode method, and the air gap method have been mainly used for the dielectric constant measurement method. A two-fluid method is used as needed.

Among them, the 3-terminal guarding electrode method is a method of measuring by inserting a sample between two parallel plate electrodes. Currently, it is widely used as an internationally standardized method.

It has an electrode structure as shown in FIG. 1, and the capacitance is expressed by Equation 1 below.

이고, d는 두 전극 사이의 거리이고 g는 중간의 주전극과 가드 전극 사이의 틈새 크기를 의미하고, ε_o는 물리상수로서 0.008854187pF/mm이며 진공의 유전율이고, ε_r은 유전체의 유전상수로서 진공에서의 유전율과 시료 재질의 유전율의 비율을 의미하는 비유전율이라고도 한다. 실험적으로 유전상수를 측정하는 방법은 동일한 간격의 평행판 전극에서 공기 중에서의 전기용량 C _a 를 측정하면 하기의 수학식 2로 표현되고, 유전체를 삽입했을 때의 전기용량 C _r 을 측정하면 하기 수학식 3으로 표현된다.where A is the width of the electrode

, d is the distance between the two electrodes, g is the size of the gap between the middle main electrode and the guard electrode, ε _o is a physical constant of 0.008854187 pF/mm, the permittivity of vacuum, ε _r is the dielectric constant of the dielectric It is also called relative permittivity, which means the ratio of the permittivity in vacuum to the permittivity of the sample material. The experimental method for measuring the dielectric constant is the capacitance in air at equally spaced parallel plate electrodes. When C _a is measured, it is expressed by Equation 2 below, and when the capacitance C _r when a dielectric is inserted, it is expressed by Equation 3 below.

Therefore, the dielectric constant of the sample is calculated by the following Equation 4 from the ratio of Equations 2 and 3.

where ε _a is the dielectric constant of air and is 1.0006.

However, in the existing standard measurement method, dimensional measurement errors such as the width of the inner electrode (low electrode) surrounded by the guard ring, the gap between the inner electrode and the guard ring, and the distance between the two electrodes are important measurement uncertainty of dielectric constant measurement. become a factor

The conventional dielectric constant measuring device applies the standard measurement method and presents the measurement uncertainty as about 1%, but considering the thickness of the sample, which means the gap between the two electrodes, the width of the guarding electrode is too small and the counter electrode is shielded. Because it is not taken into account, there is a problem in that the electric force line is greatly leaked from the edge of the electrode, resulting in a measurement error of about 1 to 20% in the actual measurement.

In order to minimize this measurement error, a study to compensate for the uncertainty that occurs when the actual width of the guarded electrode is applied, a study on the effect of the gap of the guarded electrode, and a study on the uncertainty compensation caused by the electrode edge were published.

However, in the electrode structure, the measurement error of the width of the electrode and the gap between the two electrodes, the error due to eccentricity, the thickness of the dielectric sample and the parallelism error of the upper and lower surfaces, the parallelism error of the upper and lower electrodes themselves, and the air gap caused by the surface roughness Since the error caused by an error caused by the width of the guard-ring greatly contributes to the measurement error, a new electrode structure capable of accurately measuring the dielectric constant by improving these problems is required.

The background or prior art described herein is information possessed by the inventor or acquired in the process of deriving the present invention, and is only intended to help in understanding the technical meaning of the present invention, and prior to the filing of the present invention, the technology to which the present invention belongs It is revealed that it does not mean a technique widely known in the field, and the reference numerals in the prior art are not mutually exclusive with the reference numerals in the present invention.

Republic of Korea Patent Publication No. 10-2016-0118687 Publication Date 2016.10.12

Accordingly, the present inventor comprehensively considers the above-mentioned issues and at the same time solves the technical limitations and problems of the existing technology, by applying the cross capacitance principle based on Thompson-Lampard's electrostatic theory to reduce the measurement error. The present invention was created as a result of continuous research while making great efforts to develop a new precision measuring device for dielectric constant of a solid dielectric that can minimize the effect.

Accordingly, it is an object and technical problem to be solved by the present invention to provide an apparatus for accurately measuring the dielectric constant of a solid dielectric capable of minimizing a measurement error.

Here, the technical problems and objects to be solved by the present invention are not limited to the technical problems and objectives mentioned above, and other technical problems and objects not mentioned will be clearly understood by those skilled in the art from the following description.

Specific means according to an aspect of the present invention for effectively achieving a specific technical purpose while embodying a new idea for solving the technical problem of the present invention as described above are an internal electrode, an outer peripheral surface of the internal electrode ( An external electrode that uniformly surrounds an external curved surface with a small gap, a shielding case that surrounds and insulates and shields the outer peripheral surface (outer curved surface) of the external electrode with a uniformly small gap, and the internal electrode and the external electrode In order to be electrically insulated while maintaining a uniformly minute gap therebetween, it has an electrode structure composed of four main electrodes, each including an insulator provided inside the shielding case, and a pair of symmetrically arranged top and bottom A dielectric sample was inserted between the electrodes to measure cross capacitance between the internal electrode of the upper electrode part and the external electrode of the lower electrode part, and the cross capacitance between the external electrode of the upper electrode part and the internal electrode of the lower electrode part was measured. Then, the dielectric sample is removed and the cross capacitance between the internal electrode of the upper electrode part and the external electrode of the lower electrode part is measured in the air at the same measurement distance, and the cross capacitance between the external electrode of the upper electrode part and the internal electrode of the lower electrode part is measured. By substituting one value into the equation, the dielectric constant (ε _r ) is calculated.

Accordingly, the present invention can minimize the degree of measurement error when measuring the dielectric constant of the dielectric.

In another aspect of the present invention, the external electrode may be formed of three or more rings having the same center as the internal electrode and having different diameters, and may be disposed in the shielding case at regular intervals from each other.

According to the technical idea and embodiment of the present invention, which is based on a unique solution to solve the above technical problem, an excellent effect of minimizing the measurement error to about 0.04 to 0.05% in the dielectric constant range of 2.6 to 11.9 can be obtained can

Here, the effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a cross-sectional view showing a structure of a three-terminal guard ring electrode using a conventional parallel plate electrode.
2 is a cross-sectional view showing the structure of a main electrode of an apparatus for precisely measuring the dielectric constant of a solid dielectric according to an embodiment of the present invention.
3 is a measurement result using a conventional parallel plate electrode for capacitance change obtained through a computer three-dimensional electric field simulation to find the optimal size for each size ( D, w, s, d, t ) of each electrode portion of FIG. 2 (C _a14 ) is a graph comparing the measurement result (C _a13 +C _a24 ) by the precision measuring device for dielectric constant of a solid dielectric according to an embodiment of the present invention.
4 is a cross-sectional view showing the structure of a main electrode of an apparatus for precisely measuring the dielectric constant of a solid dielectric according to another embodiment of the present invention.

Hereinafter, an embodiment according to the present invention will be described in more detail with reference to the accompanying drawings.

Prior to this, the terms described below are defined in consideration of the functions in the present invention, which indicate that they should be interpreted as concepts consistent with the technical spirit of the present invention and meanings commonly or commonly recognized in the art.

In addition, when it is determined that a detailed description of a known function or configuration related to the present invention may obscure the gist of the present invention, the detailed description thereof will be omitted.

The accompanying drawings show that parts are exaggerated or simplified for explanation of the configuration and operation of the technology and for convenience and clarity of understanding, and it is revealed that each component does not exactly match the actual size and shape.

In addition, in this specification, the term and/or is meant to include a combination of a plurality of related described items or any of a plurality of related described items, and when a part includes a certain component, it is a description that is specifically opposite Unless there is, it does not exclude other components, but means that other components may be further included.

That is, terms such as 'include' or 'comprising' and 'having' mean that the features, number, steps, operations, components, parts, or combinations thereof set forth in this specification exist, one or It is to be understood that this does not exclude the possibility of addition or existence of other features or numbers, step operation components, parts, or combinations thereof.

And terms such as upper, lower, upper, lower, upper, lower, upper, lower, front and rear, left and right are used for convenience to distinguish relative positions of each component. For example, the upper side in the drawing may be named or referred to as the upper side and the lower side as the lower side, the longitudinal direction may be named or referred to as the front-back direction, and the width direction may be named or referred to as the left/right direction.

Also, terms such as first, second, etc. may be used to describe various components. That is, terms such as 1st, 2nd, etc. may be used only for the purpose of distinguishing one component from another component. For example, a first component may be referred to as a second component without departing from the protection scope of the present invention, and the second component may also be referred to as a first component.

As shown in FIG. 2 , in the device for precisely measuring the dielectric constant of a solid dielectric according to an embodiment of the present invention, an air gap is removed whenever a dielectric sample having a thickness of 1 to 4 mm is inserted between a pair of upper and lower electrodes. It is possible to precisely control the vertical spacing in the state of being in the state of being in the same state, and it is arranged vertically and symmetrically at regular intervals so that the predetermined interval is precisely reproduced.

And the pair of upper and lower electrode parts are in the form of a ring that surrounds the inner electrodes E1 and E4 in the form of a metal disk or cylinder, and the outer peripheral surfaces (outer curved surfaces) of the inner electrodes E1 and E4 with a uniformly small gap. A shield case and inner electrodes E1 and E4 that surround and insulate the external electrodes E2 and E3 and the outer peripheral surfaces (outer curved surfaces) of the external electrodes E2 and E3 with a uniformly minute gap. An insulator ( It has an electrode structure composed of 4 main electrodes including each insulator.

That is, the insulator is fixedly disposed between the shield case and the internal electrodes E1 and E4 and the external electrodes E2 and E3.

Therefore, a solid dielectric sample having a thickness of about 1 to 4 mm is inserted between a pair of symmetrically arranged electrodes to measure the cross capacitance between the inner electrode of the upper electrode and the external electrode of the lower electrode, After measuring the cross capacitance between the external electrode of the upper electrode part and the internal electrode of the lower electrode part, the dielectric sample is removed and the cross capacitance between the internal electrode of the upper electrode part and the external electrode of the lower electrode part is removed in the air at the same measurement distance. The dielectric constant (ε _r ) can be calculated by measuring the capacitance and substituting the measured cross capacitance between the external electrode of the upper electrode part and the internal electrode of the lower electrode part into Equation 5 below.

where ε _a is the dielectric constant of air (1.0006), C _r13 is the cross capacitance between the external electrode of the upper electrode part and the internal electrode of the lower electrode part, and C _r24 is the cross capacitance between the internal electrode of the upper electrode part and the external electrode of the lower electrode part, , _Ca13 is the cross capacitance between the external electrode of the upper electrode part and the internal electrode of the lower electrode part in the air of the same measurement distance after removing the dielectric sample, and _Ca24 is the internal electrode of the upper electrode part and the internal electrode of the upper electrode part in the air at the same measurement distance after the dielectric is removed. Cross capacitance between the external electrodes of the lower electrode part.

Meanwhile, when measuring _Cr13 , the electrode corresponding to _Cr24 is grounded, and when measuring _Cr24 , the electrode corresponding to _Cr13 is grounded.

The precision measuring device for dielectric constant of a solid dielectric applying the cross capacitance principle does not need to measure the dimensions such as the width and spacing of the electrode itself, and has a structure that automatically removes voids even if the top and bottom of the dielectric sample are slightly out of complete parallelism. It does not contribute to the measurement error, and it is possible to obtain satisfactory dielectric constant measurement results by minimizing the influence of errors contributed by the surface roughness of electrodes and dielectric samples, parallelism and eccentricity of electrodes, etc.

일 때 하기의 수학식 6으로 표현된다.The Thompson-Lampard theorem is derived from four cylindrical electrodes with a symmetrical structure in vacuum.

When , it is expressed by Equation 6 below.

When this is applied to the measurement state when the dielectric sample is inserted and the measurement state in the air for a perfectly symmetric planar type electrode as shown in FIG. 2 , the following Equations 7 and 8 are respectively obtained.

은 내부전극과 외부전극 사이의 갭(gap)의 원둘레에 해당된다. 이로부터 상기의 수학식 5가 유도된다.here

is the circumference of the gap between the inner electrode and the outer electrode. From this, the above Equation 5 is derived.

On the other hand, FIG. 3 shows the measurement result (C a14 ) of the change in capacitance according to the size ( D, w, s, d, t ) of each electrode portion of FIG. 2 by a conventional parallel plate electrode through a computer three-dimensional electric field simulation (C _a14 ) It is a graph comparing the measurement result in air (C _a13 + C _a24 ) of the precision measuring device for the dielectric constant of a solid dielectric according to an embodiment of the present invention.

Here, D is the diameter of the internal electrode, w is the width of the external electrode, s is the width of the shielding case, d is the distance between the electrodes, and t is the thickness of the internal electrode and the external electrode.

That is, in the result of the conventional parallel plate electrode, as shown in Equation 1, since the capacitance is inversely proportional to the distance between the electrodes, the capacitance varies greatly depending on the distance at a distance between electrodes of 1 to 4 mm corresponding to the thickness of the actual dielectric sample. . This means that the thickness error of the sample greatly contributes to the dielectric constant measurement result.

However, C ₁ +C ₂ measured by the accurate dielectric constant measurement device of a solid dielectric according to an embodiment of the present invention shows a substantially constant parallel state in the range of 1 to 4 mm distance between electrodes corresponding to the thickness of the dielectric sample. That is, even if the thickness of the dielectric sample is slightly changed, the measurement error is negligible.

Through these results, the optimum condition for each electrode part (the condition in red in the graph) showing perfect horizontal characteristics in the interval of 1 to 4 mm between the electrodes corresponding to the thickness of the sample was confirmed.

On the other hand, more important than the horizontal characteristics in air is how accurate the dielectric constant measurement result is when the dielectric sample is inserted between the upper and lower electrodes. In order to confirm this, 6 types of standard reference material (CRM) samples are directly selected from among various dielectrics whose dielectric constant is already known through three-dimensional electric field simulation by a computer program and inserted between the given electrodes, and then the capacitance is measured. By substituting the calculated result C _r13 +C _r24 and the calculated result C _a13 +C _a24 in Equation 5, the dielectric constant value obtained was compared with the value of CRM itself to obtain an error. That is, samples that act as CRM (numbers in parentheses are dielectric constants) are Bakelite (4.8), Marble (8.3), Roger RO3010 (10.2), Silicon (11.9), Arlon AD260A (2.6), Arlon AD600 (6.15), etc. 6 species was used.

The results of verification using the dielectric constant CRM for the precision measuring device of the dielectric constant of a solid dielectric according to an embodiment of the present invention are shown in Table 1 below.

That is, it was confirmed that the measurement error was 0.04 to 0.05% in the range of the dielectric constant of 2.6 to 11.9.

Therefore, considering that the conventional 3-terminal guard ring electrode structure device using a parallel plate electrode has a dielectric constant measurement error of 1 to 10%, the precision measuring device for dielectric constant of a solid dielectric according to an embodiment of the present invention is It can be seen that it has excellent performance.

On the other hand, in the electrode structure as shown in Fig. 2 on the principle of cross capacitance measurement, since the electric field lines are concentrated only around the circumference of one gap formed by the gap between the electrodes E1 and E2, the characteristics of only a small part of the total volume of the sample are obtained. result of the measurement.

There is no problem when the material of the dielectric sample is made to be uniform as a whole, but it is necessary to improve the shape of the electrode in order to accurately measure the overall characteristics of the material of the dielectric sample in case it is not uniform.

Accordingly, the accurate dielectric constant measuring apparatus of a solid dielectric according to another embodiment of the present invention is applied by modifying the electrode structure to which the cross capacitance measurement principle can be applied as it is as it is composed of eight electrodes as shown in FIG. 4 .

That is, the external electrode has the same center as the internal electrode and is formed of three or more rings having different diameters, and is disposed in the shielding case at regular intervals from each other.

Therefore, by increasing one ring formed by the gap to three, there is an effect of measuring the properties of almost the entire sample volume, and since the measured capacitance is also increased by about 2.5 times, there is an excellent effect of increasing the reliability of the measurement. .

The results of verification using the dielectric constant CRM for the precision measuring device of the dielectric constant of a solid dielectric according to another embodiment of the present invention are shown in Table 2 below.

That is, it was confirmed that the measurement error was 0.003 to 0.03% in the range of the dielectric constant of 2.6 to 11.9.

sample

(CRM)

(CRM) C(E1/E3) C (E2/E4) C(sum)

(calculated value) U (%) Air 1.0006 0.35287 0.35288 0.70575 - - Bakelite 4.8 1.6825 1.6929 3.3854 4.79976 0.00498 Marble 8.3 2.9268 2.9270 5.8538 8.29941 0.0070 Roger 10.2 3.5957 3.5962 7.1919 10.19655 0.0338 Silicon 11.9 4.1948 4.1956 8.3904 11.89576 0.0356 AD260A 2.6 0.91675 0.91705 1.83380 2.599929 0.0027 AD600 6.15 2.1686 2.1690 4.3376 6.14977 0.0037

On the other hand, in the process of verifying the measurement error level of the precision measuring device for dielectric constant of a solid dielectric according to an embodiment of the present invention, if several CRMs with known dielectric constant values are not possessed, one or two CRMs are used as follows. It can be used after correction according to the same procedure.

That is, when a solid whose dielectric constant (ε _n ) is already known is put into the accurate dielectric constant measuring device of a solid dielectric according to an embodiment of the present invention, the measured capacitance (C _n ) and the measured capacitance in air (C _a ) is substituted into Equation 9 below to obtain a calibration value (C _c ).

From this, the correction constant (C _g ) of the electrode structure can be obtained by substituting into Equation 10 below.

Then, the dielectric constant (ε _x ) of the solid from the capacitance (C _x ) measured value when the solid to be measured is put is calculated in a corrected state by Equation 11 below.

On the other hand, the present invention is not limited by the above-described embodiment and the accompanying drawings, and can be variously modified and applied in various ways not illustrated within the scope without departing from the technical spirit of the present invention. It is clear to those of ordinary skill in the art to which the present invention pertains that it can be widely applied by changing the component substitution and other equivalent embodiments.

Therefore, the contents related to the modification and application of the technical features of the present invention should be interpreted as being included within the technical spirit and scope of the present invention.

E1, E4: internal electrode E2, E3: external electrode
D : Diameter of inner electrode w : Width of outer electrode
s : width of shielding case d : distance between electrodes
t : thickness of inner and outer electrodes

Claims (2)

internal electrode;
an external electrode surrounding the outer circumferential surface (outer curved surface) of the inner electrode with a uniformly minute gap;
a shielding case for enclosing and shielding the outer circumferential surface (outer curved surface) of the external electrode while uniformly insulating it with a minute gap; and
an insulator provided inside the shielding case to be electrically insulated while maintaining a uniformly minute gap between the inner electrode and the outer electrode;
It has an electrode structure composed of four main electrodes, each including After measuring cross capacitance and measuring cross capacitance between the external electrode of the upper electrode part and the internal electrode of the lower electrode part, the dielectric sample is removed and the internal electrode of the upper electrode part and the internal electrode of the upper electrode part in the air at the same measurement distance Measuring cross capacitance between the external electrodes of the lower electrode part, and substituting the measured cross capacitance between the external electrode of the upper electrode part and the internal electrode of the lower electrode part into Equation 5, the dielectric constant ( ε _r ), characterized in that for calculating the dielectric constant precision measurement device of the solid dielectric.
[Equation 5]

where ε _a is the dielectric constant of air (1.0006), C _r13 is the cross capacitance between the external electrode of the upper electrode part and the internal electrode of the lower electrode part in the dielectric insertion state, and C _r24 is the internal electrode of the upper electrode part and the lower electrode part in the dielectric insert state. The cross capacitance between the external electrodes, _Ca13 , is the cross capacitance between the external electrode of the upper electrode part and the internal electrode of the lower electrode part in the air at the same measurement distance after removing the dielectric sample, and _Ca24 is the dielectric sample and the upper part in the air at the same measurement distance. Cross capacitance between the internal electrode of the electrode part and the external electrode of the lower electrode part is shown.
The method of claim 1,
The external electrode is
A precision measuring device for dielectric constant of a solid dielectric, which is formed of three or more rings having the same center as the inner electrode and having different diameters and disposed in the shielding case at regular intervals from each other.

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