SU953445A1

SU953445A1 - Strap-on capacitive pickup for checking polymer film thickness

Info

Publication number: SU953445A1
Application number: SU802990777A
Authority: SU
Inventors: Юрий Алексеевич Скрипник; Николай Михайлович Свиридов; Борис Александрович Иванов; Анатолий Михайлович Свиридов
Original assignee: Киевский технологический институт легкой промышленности
Priority date: 1980-10-10
Filing date: 1980-10-10
Publication date: 1982-08-23

Description

Изобретение относится к измерительной технике и может быть использовано для контроля толщины полимерных пленок в процессе их производства.The invention relates to measuring technique and can be used to control the thickness of polymer films in the process of their production.

Известен накладной измерительный конденсатор, состоящий из >диэлек- ⁵т.рической подложки с закрепленными в одной плоскости электродами. Низкопотенциальный электрод этого конденсатора выполнен в виде замкнутого контура, окружающего высокопотенциальный' электрод (1].Known bill measuring capacitor consisting of> ⁵ t.richeskoy insulator substrate with fixed coplanar electrodes. The low-potential electrode of this capacitor is made in the form of a closed loop surrounding the high-potential 'electrode (1].

Недостатком этого датчика являются существенные погрешности измерения, обусловленные температурными ₅' изменениями геометрических размеров и диэлектрических свойств подложки. Наиболее близким техническим решением к изобретению является накгпадной емкостной датчик для контро- 20 ля толщины полимерных пленок, содержащий измерительный и эталонный конденсаторы и диэлектрическую прокладку, на противоположных рабочих поверх хностях которой нанесены электроды этих конденсаторов. Рабочие поверхности прокладки и электродов датчи- . ка выполнены плоскими, большая степень пространственной и конструктивной идентичности измерительного и эталонного конденсаторов датчика позволяет существенно уменьшить погрешности измерения, связанные с дрейфом геометрических размеров электродов и диэлектрических свойств , подложки при изменении температурыС21The disadvantage of this sensor is significant measurement errors due to temperature ₅ 'changes in the geometric dimensions and dielectric properties of the substrate. The closest technical solution to the invention is a capacitive sensor for monitoring the thickness of polymer films, comprising measuring and reference capacitors and a dielectric gasket, on the opposite working surfaces of which electrodes of these capacitors are applied. The working surface of the gasket and electrodes of the sensor. Since they are made flat, a large degree of spatial and structural identity of the measuring and reference capacitors of the sensor can significantly reduce the measurement errors associated with the drift of the geometric dimensions of the electrodes and dielectric properties of the substrate when the temperature changes C21

Недостатками известного датчика являются зависимость погрешности измерения от степени прижатия контролируемой пленки к рабочей поверхности датчика и погрешность измерения, обусловленная внешним воздействием на рабочую поверхность датчика (засорение межэлектродной поверхности, коррозия электродов, возможность короткого замыкания электродов и т.д.).The disadvantages of the known sensor are the dependence of the measurement error on the degree of pressing of the controlled film to the working surface of the sensor and the measurement error due to external effects on the working surface of the sensor (clogging of the electrode surface, corrosion of the electrodes, the possibility of a short circuit of the electrodes, etc.).

Цель изобретения - повышение том-, ности измерения. ' IThe purpose of the invention is to increase the volume of measurement. 'I

Поставленная цель достигается тем, что р, накладном емкостном датчике, содержащем измерительный и эталонный конденсаторы и диэлекцелью исключения влияния на результат измерения анизотропных свойств контролируемой пленки могут быть выполнены в виде концентрических комп₅ ланарных колец (фиг. 2). Количество электродов, геометрические размеры трическую прокладку, на противоположных рабочих поверхностях которой нанесены электроды этих конденсаторов, рабочие поверхности диэлек- ю трической прокладки и электродов покрыты стойким к истиранию диэлек^ трическим слоем и выполнены выпуклыми с радиусом кривизны, выбраннымThis goal is achieved by the fact that p, a surface-mounted capacitive sensor containing measuring and reference capacitors and a dielectric to exclude the influence of the anisotropic properties of the controlled film on the measurement result, can be made in the form of concentric sets of ₅ lanar rings (Fig. 2). The number of electrodes, the geometrical dimensions of the strip, on the opposite working surfaces of which are applied the electrodes of these capacitors, the surfaces of the dielectric strip and the electrodes are coated with an abrasion-resistant dielectric layer and made convex with a radius of curvature selected

R из соотношения zct , ’⁵ <3 где R - радиус кривизны рабочих поверхностей;R from the relation zct, ' ⁵ <3 where R is the radius of curvature of the working surfaces;

d - диаметр окружности конденсатора; 20 ! a = const;d is the diameter of the circumference of the capacitor; 20 ! a = const;

а = 3“5 ~ для полимерных пленок, жесткость которых находится в пределах 5-10’⁹-1,2 «КГ? нм; ²⁵ а = 5*7 * Для полимерных пленок, жесткость которых больше 1,2-1 О*⁵ нм;а = 3 “5 ~ for polymer films whose rigidity is in the range of 5-10 ' ⁹ -1,2" KG? nm; ²⁵ a = 5 * 7 * For polymer films whose rigidity is greater than 1.2-1 O * ⁵ nm;

Кроме тоНо, диэлектрический слой может быть выполнен из плавленного ³⁰кварца.In addition, the dielectric layer can be made of fused ³⁰ quartz.

На фиг. 1 изображен накладной емкостной датчик для контроля толщины полимерных пленок, фронтальный разрез; на фиг. 2 - датчик со стороны 35 рабочей поверхности.In FIG. 1 shows an overhead capacitive sensor for monitoring the thickness of polymer films, a frontal section; in FIG. 2 - sensor from side 35 of the working surface.

Накладной емкостной датчик состоит из измерительного конденсатора 1 и эталонного конденсатора 2, имеющих низкопотенциальные электроды 3 и 4 и высокопотенциальные электроды 5 и 6. Конденсаторы размещены с разных сторон диэлектрической прокладки 7, выполненной из материала с большим коэффициентом теплопровод- 45 ности. Поверхность датчика защищена диэлектрическим слоем 8, стойким к истиранию.The on-board capacitive sensor consists of a measuring capacitor 1 and a reference capacitor 2 having low-potential electrodes 3 and 4 and high-potential electrodes 5 and 6. The capacitors are placed on different sides of the dielectric strip 7 made of a material with a high thermal conductivity 45. The surface of the sensor is protected by a dielectric layer 8, resistant to abrasion.

Рабочие поверхности диэлектрической прокладки, следовательно и элек- ⁵⁰тродов 3*6, конденсаторов 1 и 2, нанесенных, например напылением на противоположных рабочих поверхностях прокладки, выполнены выпуклыми (сферическими или цилиндрическими) с оди- 55 наковым. радиусом кривизны.The working surfaces of dielectric spacers, and hence electrical trodes ⁵⁰ 3 * 6, the capacitors 1 and 2 are applied, for example coated on the opposite surfaces of the working lining, are convex (spherical or cylindrical) 55 with identical Nakov. radius of curvature.

Низко- и высокопотенциальные электроды 3*6 конденсаторов 1 и 2 с , и расстояние между ними определяются предполагаемой толщиной контролируемой пленки.Low and high potential electrodes 3 * 6 of capacitors 1 and 2 s, and the distance between them is determined by the estimated thickness of the controlled film.

Радиус кривизны рабочей поверхности емкостного датчика выбирается в соответствии с прочностными харак теристиками контролируемого матет риала, а также с учетом геометрических размеров конденсаторов. С дос таточной степенью достоверности он может быть β шения аThe radius of curvature of the working surface of the capacitive sensor is selected in accordance with the strength characteristics of the controlled material, as well as taking into account the geometric dimensions of the capacitors. With a sufficient degree of certainty, it can be β of solution a

визны рабочих определен из соотно, , где R - радиус криповерхностей;· d - диа метр-окружности конденсатора;, a = const;visas of workers is determined from, respectively, where R is the radius of the cryptosurfaces; · d is the diameter of the capacitor circle ;, a = const;

а = 3”5 “ для полимерных пленок, . жесткость которых на, ходится в пределаха = 3 ”5“ for polymer films,. the stiffness of which is within

5· 10~⁹-1,2·10³ нм;5 · 10 ~ ⁹ -1.2 · 10 ³ nm;

а = 5*7 “ для полимерных пленок, жесткость которых боль ше 1 ,2 *10~³ нм.а = 5 * 7 “for polymer films whose rigidity is greater than 1, 2 * 10 ~ ³ nm.

II

Выполнение рабочих поверхностей датчика выпуклыми исключает появление воздушного зазора между ним и контролируемой полимерной пленкой при изменении силы прижатия между ними.The implementation of the convex working surfaces of the sensor eliminates the appearance of an air gap between it and the controlled polymer film with a change in the pressing force between them.

Благодаря покрытию электродов 3-6 и межэлектродных промежутков стойким к истиранию диэлектрическим слоем 8 (например кварцем) предотвращается засорение датчика и коррозия электродов, а также исключается возможность короткого замыкания электродов датчика. Толщина защитного диэлектрического слоя 8 может быть различной (от 1 мкм до 1000 мкм) и определяется твердостью, электропроводностью и толщиной контролируемой пленки, а также степенью выпучивания электрического поля (краевого эффекта) между электродами датчика.Due to the coating of electrodes 3-6 and interelectrode gaps with an abrasion resistant dielectric layer 8 (for example, quartz), clogging of the sensor and corrosion of the electrodes are prevented, and the possibility of a short circuit of the sensor electrodes is also eliminated. The thickness of the protective dielectric layer 8 can be different (from 1 μm to 1000 μm) and is determined by the hardness, electrical conductivity and thickness of the controlled film, as well as the degree of buckling of the electric field (edge effect) between the sensor electrodes.

Накладной емкостной датчик работает следующим образом.Overhead capacitive sensor operates as follows.

Полимерная пленка, толщина которой контролируется в процессе изготовления, накладывается на рабочую поверхность измерительного конденсатора 1. При ее перемещении изменяется суммарная емкость конденсатораA polymer film, the thickness of which is controlled during the manufacturing process, is superimposed on the working surface of the measuring capacitor 1. When it moves, the total capacitance of the capacitor changes

953445 6953445 6

1, пропорциональная усредненному по ' площади касания значению толщины пленки. Так как емкость эталонного конденсатора 2, идентичного измерительному конденсатору 1, при этом 5 остается неизменной, то сравнение значений емкостей конденсаторов 1 и 2 позволяет исключить влияние на результаты измерения дестабилизирующих факторов, таких, как температу- ю ра й влажность окружающей среды, существенно влияющих на геометрические размеры электродов 36 и диэлектрические свойства подложки 7·1, proportional to the film thickness averaged over the 'contact area'. Since the capacitance of the reference capacitor 2, which is identical to the measuring capacitor 1, remains 5 unchanged, a comparison of the capacitance values of the capacitors 1 and 2 eliminates the influence of destabilizing factors on the measurement results, such as the temperature and humidity of the environment, which significantly affect the geometric dimensions of the electrodes 36 and the dielectric properties of the substrate 7 ·

Выполнение рабочих поверхностей 15 конденсаторов выпуклыми обеспечивает прилегание полимерной пленки по всей контролируемой поверхности без зазора, что обуславливает высокую точность измерения ее толщины, а на- 20 несение на рабочую поверхность стойкого к истиранию диэлектрического слоя,° например слоя плавленного кварца, обеспечивает отсутствие микрочастиц материала контролируемой 25 пленки и пыли в межэлектродном пространстве, препятствует прохождению сквозного тока проводимости между электродами, исключает возможность замыкания электродов датчика, зо а также предотвращает их коррозию, что также повышает точность измерения.The execution of the working surfaces of the 15 capacitors convex ensures the adhesion of the polymer film over the entire surface under control without a gap, which leads to a high accuracy of measuring its thickness, and the application of a dielectric layer resistant to abrasion, such as a fused silica layer, to the work surface, ensures the absence of microparticles of the material controlled 25 films and dust in the interelectrode space, prevents the passage of the through conductivity current between the electrodes, eliminates the possibility of short circuit sensor electrodes, and also prevents their corrosion, which also increases the accuracy of the measurement.

Claims

The invention relates to a measuring technique and can be used to control the thickness of polymer films in the course of their production. A metering capacitor is known, consisting of a dielectric substrate with electrodes attached in the same plane. The low potential electrode of this capacitor is made in the form of a closed loop surrounding the high potential electrode 1. A disadvantage of this sensor is the substantial measurement errors due to temperature changes in the geometric dimensions and dielectric properties of the substrate. The closest technical solution to the invention is a capacitive capacitance sensor for monitoring the thickness of polymer films, containing a measuring and reference capacitors and a dielectric strip, on the opposite working surfaces of which are deposited the electrodes of these capacitors. The working surfaces of the gasket and the sensor electrodes are flat. The greater degree of spatial and constructive identity of the measuring and reference capacitors of the sensor significantly reduces the measurement errors associated with the drift of the geometric dimensions of the electrodes and the dielectric properties of the substrate when the temperature changes from 21 ° C. The disadvantages of the known sensor are the dependence of the measurement error on the degree of pressure of the monitored film to the working surface of the sensor and the measurement error caused by an external impact on the working surface of the sensor (clogging of the electrode surface, corrosion of the electrodes, the possibility of short-circuit electrodes, etc.). 39 The purpose of the invention is to improve the accuracy of the measurement. The goal is achieved by the fact that p, a superimposed capacitive sensor containing a measuring and reference capacitors and a dielectric strip, on the opposite working surfaces of which are applied the electrodes of these capacitors, the working surfaces of the dielectric strip and electrodes are coated with an abrasion-resistant dielectric layer and made convex with a radius of curvature , selected from the relation - sQ, d where R is the radius of curvature of the working surfaces; d is the diameter of the capacitor; a const; and 3-5 for polymer knots, the rigidity of the ryh is in the limit of 5-10 -1.2 "103; a 5-7 for polymer films whose pain is 1.2-103 nm; In addition to Toho, the dielectric layer can be made of fused quartz. Fig. 1 shows a capacitive sensor for monitoring the thickness of polymer films; frontal section; in fig. 2 - sensor from the side of the working surface. The surface-mounted capacitive sensor consists of the measuring capacitor 1 and the reference capacitor 2, which have low-potential electrodes 3 and 4 and high-potential electrodes 5 and 6. The capacitors are placed on different sides of the dielectric strip 7 made of a material with a large heat transfer coefficient. The surface of the sensor is protected by a dielectric layer 8, resistant to abrasion. The working surfaces of the dielectric strip, and hence of the electrodes of capacitors 1 and 2, deposited, for example, by sputtering onto the opposite working surfaces of the strip, are made convex (spherical or cylindrical) with uniform ones. radius of curvature. The low and high potential electrodes of capacitors 1 and 2 can be made in the form of concentric coplanar rings (Fig. 2) in order to eliminate the effect on the measurement result of the anisotropic properties of the controlled film. The number of electrodes, the geometrical dimensions and the distance between them are determined by the estimated thickness of the monitored film. The radius of curvature of the working surface of the capacitive sensor is selected in accordance with the strength characteristics of the material being monitored, as well as taking into account the geometric dimensions of the capacitors. With a sufficient degree of reliability, it can be determined from the relation R where R is the radius of the working surfaces; d is the diameter-circle of the capacitor ;, and const; and 3-5 for polymer films whose rigidity is in the range of 5-103-1, 2-103 nm; and 5-7 for polymer films whose rigidity is greater than 1, 240 nm. Making the working surfaces of the sensor convex eliminates the appearance of an air gap between it and the controlled polymer film when the pressing force between them changes. By covering the electrodes 3-6 and the interelectrode gaps, the abrasion-resistant dielectric layer 8 (for example, quartz) prevents clogging of the sensor and corrosion of the electrodes, and also eliminates the possibility of short-circuiting the sensor electrodes. The thickness of the protective dielectric layer 8 can be different (from 1 micron to 1000 microns) and is determined by the hardness, electrical conductivity and thickness of the film being monitored, as well as the degree of electric field bulging (edge effect) between the sensor electrodes. Invoiced capacitive sensor operates as follows. The polymer film, the thickness of which is controlled during the manufacturing process, is superimposed on the working surface of the measuring capacitor 1. As it moves, the total capacitance of the capacitor 5 1 changes, is proportional to the film thickness averaged over the touch area. Since the capacitance of the reference capacitor 2, which is identical to the measuring capacitor 1, remains unchanged, comparing the capacitance values of the capacitors 1 and 2 eliminates the influence on the measurement results of destabilizing factors, such as temperature and humidity of the environment, which significantly affect the geometrical electrode dimensions and dielectric properties of the substrate. Making the working surfaces of the capacitors convex ensures the adherence of the polymer film over the entire controlled surface without The gap, which leads to high accuracy in measuring its thickness, and ensuring that a dielectric layer, such as a layer of fused quartz, abrades on the working surface, ensures the absence of microparticles of controlled film material and dust in the interelectrode space, prevents the passage of conduction through current between the electrodes, eliminates the possibility of closure of the sensor electrodes, as well as prevents their corrosion, which also increases the measurement accuracy. Claims of Invention A surface-mounted capacitive sensor for monitoring the thickness of polymer films containing a measuring and reference capacitors and a dielectric strip, on the opposite working surfaces of which are deposited the electrodes of these capacitors, characterized in that, to improve the accuracy of the measurement, the working surfaces of the dielectric strip and electrodes are covered an abrasion-resistant dielectric layer and are made convex with a radius of curve - R = R, selected from the relation - sd, - id. where R is the radius of curvature of the working SCP surfaces; d is the diameter of the capacitor; a const; for polymer films whose rigidity is within (, 240 nm; and for polymer films whose rigidity is greater than 1.2 to 10 nm. 2. The sensor according to claim 1, characterized in that the dielectric layer is made of fused quartz. Information sources , taken into consideration by an expert; ize 1. USSR author's certificate No., class G 01 B 7/06, 1968.

2. Skripnik Yu.A. Sviridov N.M. r Burmystenkov-.t.A.n. and Sviridov A.M. Measurement of the thickness of dielectric materials. Lime. Universities, Technologists of light industry, 1980 № 5, p. 106-109 (prototype).