JP2013101808A - Microwave heating device and microwave heating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave heating device and a microwave heating method capable of properly heating a film of a conductor and a film of a dispersion formed by dispersing the conductor.SOLUTION: While supplying a microwave having 1 m to 1 mm of a wavelength range to a microwave tube 16a, in the microwave tube 16a, a substrate 24 forming a film of a conductor and the film of a dispersion formed by dispersing the conductor is disposed in a position where the forming surface of the film becomes parallel to the magnetic line direction of the microwave and the maximum point of a magnetic field of the microwave is included, and the position thereof is moved.

Description

  The present invention relates to a microwave heating apparatus and a microwave heating method.

  2. Description of the Related Art Conventionally, a technique for heat-treating materials such as metals or their thin films using microwaves is known. When using microwaves, the object to be heated can be heated internally by the action of an electric field or magnetic field to selectively heat it.

  As an example of microwave heating, in Patent Document 1 (particularly paragraph 0073, etc.) described below, a thin film formed from an inorganic metal salt material that is a precursor of a metal oxide semiconductor is subjected to atmospheric pressure (in the presence of oxygen). A technique for irradiating a microwave and converting it into a semiconductor is disclosed.

  Further, in Patent Document 2 (particularly, paragraph 0024), heating is performed while passing a workpiece such as a cemented carbide, cermet, or ceramic cutting plate through a tunnel in which microwave sources (magnetrons) are arranged at equal intervals. Techniques to do this are disclosed.

  Further, in the following Patent Document 3 (particularly paragraph 0019, etc.), microwave heating is performed by efficiently installing a grindstone material at a position where the electric field or magnetic field of the standing wave (combination of incident wave and reflected wave) is maximum. An apparatus is disclosed.

JP 2009-177149 A JP 2006-300509 A JP 2010-274383 PR

  In general, when a conductor or semiconductor film or a film of a dispersion in which a conductor or semiconductor is dispersed is heated by microwaves, the substrate on which these films or films are formed due to the occurrence of sparks may be appropriately heated. There is a problem that it is difficult. The above conventional technology does not disclose a configuration that solves this problem.

  An object of the present invention is to provide a microwave heating apparatus and a microwave heating method capable of appropriately heating a conductor film or a dispersion film in which a conductor is dispersed.

  In order to achieve the above object, one embodiment of the present invention is a microwave heating apparatus, comprising: a waveguide; and a microwave supply unit that supplies a microwave having a wavelength range of 1 m to 1 mm to the waveguide. In the waveguide, a substrate on which a conductor film or a dispersion film in which conductors are dispersed is formed, and the film formation surface is substantially parallel to the direction of the line of magnetic force of the microwave, and the magnetic field of the microwave And a substrate supply means for moving the position.

  The thickness of the film is preferably 1 μm to 30 μm.

  The substrate is made of a base material containing polyimide, polyester, polycarbonate, paper phenol, glass epoxy, alumina, silica, zirconia, titania, silicon or silicon carbide.

  The conductor is gold, silver, copper, aluminum, nickel, graphite, graphene, or carbon nanotube.

  Moreover, one embodiment of the present invention is a microwave heating method, in which a microwave having a wavelength range of 1 m to 1 mm is supplied into a waveguide, and a conductor film or a conductor is dispersed in the waveguide. The substrate on which the film of the dispersion is formed is arranged at a position where the film forming surface is substantially parallel to the direction of the magnetic field lines of the microwave and includes the maximum point of the magnetic field of the microwave, or the position is moved. It is characterized by that.

  According to the present invention, the generation of a spark can be suppressed and heated appropriately by making the surface of the substrate on which the film is formed substantially parallel to the direction of the line of magnetic force of the microwave.

It is a figure showing the example of composition of the microwave heating device concerning an embodiment. It is a figure which shows the structural example of the waveguide which comprises a heating part. It is explanatory drawing of the electromagnetic field distribution of the microwave which generate | occur | produces in a waveguide. It is sectional drawing of the board | substrate with which the film | membrane of the film | membrane of the conductor or the conductor which disperse | distributed the conductor was formed. It is explanatory drawing of the application | coating area | region of the ink formed in the slide glass. 6 is an explanatory diagram of the arrangement of substrates in a waveguide in Comparative Example 1. FIG. 6 is an explanatory diagram of the arrangement of substrates in a waveguide in Comparative Example 1. FIG.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 shows a configuration example of a microwave heating apparatus according to this embodiment. In FIG. 1, the microwave heating apparatus includes a microwave generation unit 10, a monitor unit 12, a tuner unit 14, a heating unit 16, a heated object supply unit 18, and a movable short-circuit unit 20.

  The microwave generation unit 10 generates a microwave to be supplied to the waveguide constituting the heating unit 16. Here, the microwave is an electromagnetic wave having a wavelength range of 1 m to 1 mm (frequency is 300 MHz to 300 GHz).

  The monitor unit 12 is a device that monitors the incident power of the microwave generated by the microwave generation unit 10 and the reflected power from the heating unit 16.

  The tuner unit 14 generates an electromagnetic wave having a phase opposite to that of the reflected wave generated when the microwave enters the waveguide constituting the heating unit 16 to cancel the reflected wave, and the reflected wave is transmitted to the microwave generating unit 10. Prevent return.

  As described above, the heating unit 16 is configured by a waveguide, and heats an object to be heated by microwaves. As will be described later, in the present embodiment, the object to be heated is heated using the energy of the magnetic field among the energy of the microwave.

The heated object supply unit 18 includes a microwave leakage prevention mechanism, and supplies the heated object to the waveguide constituting the heating unit 16. The heated object supply unit 18 may be, for example, an opening for supplying the heated object formed in the waveguide. In this case, the object to be heated is manually inserted into the waveguide from the opening. Moreover, it is good also as a structure which supplies a to-be-heated target object in a waveguide with appropriate supply apparatuses, such as roll-to-roll. In the present embodiment, the object to be heated is a conductor film formed on a substrate or a dispersion film in which conductors are dispersed. In the present application, the conductor means a substance having a resistivity of 10 ³ Ωcm or less.

  The movable short-circuit portion 20 maintains the standing wave in the waveguide when the wavelength of the microwave in the waveguide constituting the heating portion 16 is shortened due to the material of the object to be heated and the standing wave changes. The tip portion 20a is arranged at an optimum position for monitoring the reflected power of the monitor unit 12 and maintaining a standing wave.

  FIG. 2 shows a configuration example (TE10 mode cavity resonator) of a waveguide constituting the heating unit 16. In FIG. 2, the tuner section 14 is provided on the side of receiving a microwave in the waveguide. In addition, an iris portion 22 is formed at the entrance of the microwave, and the microwave enters the waveguide 16 a through the opening of the iris portion 22. Moreover, in FIG. 2, the to-be-heated target supply part 18 is shown with the broken line. The wave of the microwave Mw in FIG. 2 shows a curve of electric field intensity (the highest point of the wave (amplitude) (the highest point of the curve) is the maximum electric field point, and the lowest point (the lowest limit of the curve is the lowest electric field point)). Yes.

The movable short-circuit portion 20 is provided in the vicinity of the end of the waveguide 16a opposite to the iris portion 22 and is covered by the magnetic field of the microwave Mw existing between the iris portion 22 and the movable short-circuit portion 20. The object to be heated supplied from the heating object supply unit 18, that is, the film formed on the substrate 24 is heated. The range of influence of this magnetic field varies depending on the frequency (wavelength) of the microwave. For example, in the case of 2.45 GHz (about 148 mm), the range is about +/− 15 mm from the maximum point of the magnetic field strength. In order to generate a standing wave of the microwave Mw between the iris part 22 and the movable short-circuit part 20, the distance L between the iris part 22 and the tip part 20a is
L = (2n−1) λg / 2
λg may be a wavelength of the microwave Mw in the waveguide, and n may be a natural number. However, the microwave generated in the waveguide 16a is not limited to a standing wave, and may be a traveling wave.

  FIGS. 3A, 3B and 3C are explanatory diagrams of the electromagnetic field distribution of the microwave generated in the waveguide 16a.

  FIG. 3A is a perspective view of the waveguide 16a, and the waveguide 16a extends in a direction (z-axis direction) orthogonal to the xy plane of the drawing. When a microwave is supplied to the waveguide 16a, a magnetic field is generated in the x-axis direction (direction perpendicular to the yz plane). Magnetic field lines representing the magnetic field at this time are indicated by broken arrows. The electric field is generated in the y-axis direction perpendicular to the magnetic field, and the lines of electric force are indicated by solid arrows.

  FIG. 3B is a cross-sectional view taken along a plane parallel to the xz plane of the waveguide 16a. In FIG. 3 (b), the microwave electric field lines are indicated by white circles (◯) and black circles (●), the white circles are directed from the front side of the paper to the back side, and the black circles are directed from the back side of the paper to the front side. It is an electric field line in the direction of heading. The magnetic field lines are indicated by broken lines.

  As shown in FIG. 3B, the surface of the substrate 24 on which the conductor film or the dispersion film in which the conductor is dispersed is maintained substantially parallel to the direction of the lines of magnetic force (direction of the magnetic field). It arrange | positions in the waveguide 16a in a state, or moves in the waveguide 16a. Thereby, induction heating by a magnetic field can be performed on the film. Here, “substantially parallel” means a state in which the surface of the substrate 24 and the direction of the magnetic force lines of the microwave are parallel or maintain an angle of 30 degrees or less with respect to the direction of the magnetic force lines. The angle within 30 degrees refers to a state in which the normal and the direction of the magnetic force lines standing on the surface of the substrate 24 form an angle of 60 degrees or more. Further, the position in the waveguide 16a where the substrate 24 is arranged or moved is a position including the center of the vortex of the magnetic field lines of microwaves (a position including the maximum magnetic field point). On the surface of the substrate 24, a conductor film or a dispersion film in which conductors are dispersed, which is an object to be heated, is formed. For this reason, lines of magnetic force penetrate into the film, and the object to be heated can be selectively heated by internally generating heat without generating a spark due to magnetic loss. Therefore, it is not necessary to heat the entire substrate 24 with an oven or the like. When a semiconductor substrate such as silicon or silicon carbide is used, the substrate itself generates heat when heated by microwaves, but the film is completely sintered in a short time. As a result, the substrate 24 and the conductor film formed on the surface thereof or the dispersion film in which the conductor is dispersed can be appropriately heated without being damaged.

  FIG. 3C is a cross-sectional view taken along a plane parallel to the yz plane of the waveguide 16a. In FIG. 3C, the magnetic field lines of the microwave are indicated by white circles (◯) and black circles (●), the white circles are directed from the front side of the paper to the back side, and the black circles are directed from the back side of the paper to the front side. Magnetic field lines. As described above, the film formation surface of the substrate 24 is arranged so as to be substantially parallel to the direction of the magnetic force lines of the microwave.

  The substrate 24 is preferably arranged in a region where the density of magnetic lines of force in the waveguide 16a is high, that is, a position including the maximum point of the magnetic field of the microwave, or the position is allowed to pass therethrough. Note that the electric field is minimum at the maximum magnetic field point. At this time, if the substrate 24 is arranged in an area within 3 cm in length and width including the position where the magnetic field is maximized, the occurrence of sparks can be suppressed, and the dispersion of the substrate 24 and the conductor film or conductor formed on the surface thereof is dispersed. It is possible to prevent the material film from being damaged.

  FIG. 4 shows a cross-sectional view of the substrate 24 on which a conductor film or a dispersion film in which conductors are dispersed is formed. In FIG. 4, a conductor film 26 or a dispersion film 26 in which conductors are dispersed is formed on at least one surface of a substrate 24. The thickness of the substrate is preferably in the range of 0.01 to 10 mm. The thickness of the film is preferably in the range of 100 nm to 100 μm, and preferably in the range of 1 μm to 30 μm from the viewpoint of easy heat generation. A film thinner than 100 nm has less loss, and a film thicker than 100 μm does not penetrate the magnetic lines to the inside, and in any case, induction heating is difficult.

  Examples of the conductor include gold, silver, copper, aluminum, nickel, graphite, graphene, and carbon nanotube. A known resin can be used as a dispersion medium for dispersing the conductor. Examples of these resins include cellulose, polyvinyl pyrrolidone, polyethylene glycol, polypropylene glycol, and epoxy resin. Examples of the material of the substrate 24 include a base material containing polyimide, polyester, polycarbonate, paper phenol, glass epoxy, alumina, silica, zirconia, titania, silicon, or silicon carbide. The substrate 24 is inserted into the waveguide 16a from the heated object supply unit 18 provided in the waveguide, and the film formation surface is not in the waveguide by the substrate holding and moving means (not shown). You may arrange | position in a waveguide or move in a waveguide so that it may become substantially parallel to the magnetic force line direction of a microwave.

  Examples of the present invention will be specifically described below. In addition, the following examples and comparative examples are for facilitating understanding of the present invention, and the present invention is not limited to these examples.

Example 1
A polyimide film manufactured by Toray DuPont Co., Ltd .; Kapton 150EN (film thickness: 37.5 μm) was used as a substrate, and a silver (Ag) paste (Dotite FA-353N manufactured by Fujikura Kasei Co., Ltd.) was applied to the surface of the substrate.

  The silver paste was applied by printing a 2 cm × 2 cm square pattern on the substrate by screen printing. The thickness of the printed pattern (silver paste layer) was 6 μm (three-point average value) after drying.

  The substrate on which the silver paste was applied as described above to form a silver paste layer was subjected to microwave heating (heating by a magnetic field) using the apparatus shown in FIG. At this time, as described above, the substrate 24 is disposed in a position in which the surface coated with the silver paste is substantially parallel to the direction of the magnetic force lines of the microwave and includes the maximum point of the microwave magnetic field. . The frequency of the microwave used was 2.45 GHz, and the maximum point of the magnetic field (minimum point of the electric field) at this time was theoretically located away from the iris part 22 by λg / 2 (distant from the maximum point of the electric field by λg / 4). The position (λg is 148 mm when using a 2.45 GHz microwave) is set, but when the substrate is set, the wavelength of the microwave traveling through the substrate is shortened, and the resonance position is shifted. Therefore, a microwave detector is arranged at the maximum point of the electric field that is λg / 4 away from the iris part 22, and the position of the plunger is set at the position where the voltage of the voltmeter in the waveguide connected to the microwave detector shows the maximum value. Make fine adjustments. The heating time is 30 to 60 seconds. Thereby, the surface temperature of the silver paste layer rose to about 200 ° C., and the silver particles were sintered to produce a silver film. At this time, the substrate 24 was not dissolved. Further, no spark was generated during microwave heating, and a silver film could be formed on the surface of the substrate 24 without damaging it. The film thickness of the formed silver film was 8 μm. The resistivity of the silver paste layer and the silver film before and after the heat treatment was measured as a three-point average value using a Loresta GP manufactured by Mitsubishi Chemical Analytech Co., Ltd. The measurement results are shown in Table 1.

Example 2
An ink in which aluminum particles were dispersed was prepared by the following procedure.

  4.0 g of aluminum powder (RD10-3560 manufactured by Toyo Aluminum Co., Ltd., D50 = 13 μm), 4.0 g of 35% γ-butyrolactone solution of phenoxy type epoxy resin (manufactured by jER1256 Japan Epoxy Resin Co., Ltd.), 4.0 g of γ-butyrolactone Mix well to obtain a uniform dispersant. The particle size of the aluminum powder was measured using a Microtrack particle size distribution measuring device MT3000II series USVR manufactured by Nikkiso Co., Ltd.

  In the same manner as in Example 1, the above dispersant was printed on a substrate surface of Kapton 150EN (film thickness 37.5 μm) manufactured by Toray DuPont with a square pattern of 2 cm × 2 cm by screen printing, and a film in which aluminum was dispersed (Aluminum dispersion layer) was formed. The film thickness after drying was 15 μm (three-point average value). Thereafter, microwave heating was performed in the same manner as in Example 1. An aluminum film could be formed on the surface of the substrate without dissolving the substrate during microwave heating, without generating sparks, and without damaging the substrate. The film thickness of the formed aluminum film was 21 μm. The resistivity of the aluminum dispersion layer and the aluminum film before and after the heat treatment was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

Example 3
An ink in which copper particles were dispersed was prepared by the following procedure.

  4.0 g of copper powder (1100Y Mitsui Mining & Smelting Co., Ltd. D50 = 1.1 μm), 2.0 g of 20% γ-butyrolactone solution of phenoxy type epoxy resin (jER1256 Japan Epoxy Resin Co., Ltd.), 1.0 g of glycerin Mix to make a uniform dispersant. The particle size of the copper powder was measured using a nano particle size distribution measuring device UPA-UT151 manufactured by Nikkiso Co., Ltd.

  In the same manner as in Example 1, the above dispersant was printed on a substrate surface of Kapton 150EN (film thickness: 37.5 μm) manufactured by Toray DuPont with a square pattern of 2 cm × 2 cm by screen printing, and a film in which copper was dispersed (Copper dispersion layer) was formed. The film thickness after drying was 3 μm (three-point average value). Thereafter, microwave heating was performed in the same manner as in Example 1. It was possible to form a copper film on the surface of the substrate without dissolving the substrate during microwave heating, without generating sparks, and without damaging the substrate. The film thickness of the formed copper film was 4 μm. In the same manner as in Example 1, the resistivity of the copper dispersion layer and the copper film before and after the heat treatment was measured. The measurement results are shown in Table 1.

As shown in Table 1, the silver paste layer before the heat treatment of Example 1 had a resistivity of 2.10E-04 (2.10 × 10 ⁻⁴ ) Ωcm after the microwave heat treatment. In the silver film, the resistivity decreased to 1.03 × 10 ⁻⁵ Ωcm. Moreover, in the aluminum dispersion layer formed with the ink in which the aluminum particles of Example 2 were dispersed, the resistivity could not be measured (the resistivity was higher than the upper limit of measurement of the measurement apparatus), but after the microwave heat treatment In the aluminum film, the resistivity decreased to 3.45 × 10 ⁻³ Ωcm. Moreover, in the copper dispersion layer formed with the ink in which the copper particles of Example 3 were dispersed, the resistivity could not be measured (the resistivity was higher than the measurement upper limit of the measuring device), but after the microwave heat treatment In the copper film, the resistivity decreased to 2.18 × 10 ⁻² Ωcm.

  As described above, a metal film having a low resistivity could be formed by forming a film of a dispersion of silver, aluminum, and copper on a substrate and performing microwave heating. According to the present example, each metal particle could be internally heated without generating a microwave spark, and the resistivity of the metal film could be reduced efficiently.

Comparative Example 1
In the same manner as in Example 1, the silver paste was printed in a square pattern of 2 cm × 2 cm by screen printing on the substrate surface of Kapton 150EN (film thickness: 37.5 μm) manufactured by Toray DuPont. The thickness of the printed pattern (silver paste layer) was 15 μm (three-point average value) after drying.

  The substrate 24 coated with the silver paste as described above to form a silver paste layer is placed in the waveguide shown in FIG. 2, FIG. 3 (b), (c), FIG. 6, FIG. 7 (b), Arranged as shown in (c), microwave heating was performed. In the arrangement of the substrate 24 of the first comparative example, as shown in FIGS. 6, 7B, and 7C, the maximum point of the microwave magnetic field is off and the silver paste on the substrate 24 is used. The applied surface is a direction substantially orthogonal to the direction of the electric lines of force of the microwave. For this reason, most of the electric field lines of microwaves are received by the coated surface of the silver paste, a spark is generated, and the substrate 24 and the silver paste layer are damaged. From this result, it is necessary to arrange the direction of the substrate surface in a direction substantially parallel to the direction of the magnetic force line of the microwave and in a position including the maximum point of the magnetic field of the microwave as in Examples 1 to 3. I know that there is.

Comparative Examples 2-4
In Examples 1 to 3, external heating was performed at 200 ° C. for 1 hour using an electric oven (a constant temperature bath) instead of microwaves, and the resistivity of each metal dispersion layer and each metal film before and after the heat treatment was measured. The measurement results are shown in Table 2.

  As shown in Table 2, the resistivity cannot be measured for an aluminum dispersion layer formed using an ink in which aluminum particles are dispersed and a copper dispersion layer formed using an ink in which copper particles are dispersed. (The resistivity was higher than the upper limit of measurement of the measuring device). Moreover, it turns out that the resistivity after heat processing is higher also about the film | membrane (silver paste layer) formed using Ag paste than the case of a microwave heat processing (Example 1).

  DESCRIPTION OF SYMBOLS 10 Microwave generation part, 12 Monitor part, 14 Tuner part, 16 Heating part, 16a Waveguide, 18 Heated object supply part, 20 Movable short circuit part, 20a Tip part, 22 Iris part, 22a Tip part, 24 Substrate , 26 Membrane.

Claims (5)

A waveguide;
Microwave supply means for supplying a microwave having a wavelength range of 1 m to 1 mm to the waveguide;
In the waveguide, a substrate on which a conductor film or a dispersion film in which conductors are dispersed is formed, the surface on which the film is formed is substantially parallel to the direction of the magnetic force lines of the microwave, and the microwave magnetic field A substrate supply means arranged at a position including the maximum point or moving the position;
A microwave heating apparatus comprising:   The microwave heating apparatus according to claim 1, wherein the film has a thickness of 1 μm to 30 μm.   The said board | substrate is comprised by the base material containing a polyimide, polyester, a polycarbonate, paper phenol, a glass epoxy, an alumina, a silica, a zirconia, a titania, a silicon, or a silicon carbide, The Claim 1 or Claim 2 characterized by the above-mentioned. Microwave heating device.   The microwave heating device according to any one of claims 1 to 3, wherein the conductor is gold, silver, copper, aluminum, nickel, graphite, graphene, or a carbon nanotube. Supplying microwaves in the wavelength range of 1 m to 1 mm into the waveguide;
In the waveguide, a substrate on which a conductor film or a dispersion film in which conductors are dispersed is formed, the surface on which the film is formed is substantially parallel to the direction of the magnetic force lines of the microwave, and the microwave magnetic field Place it at a position including the maximum point, or move that position.
The microwave heating method characterized by the above-mentioned.

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