WO2012074024A1 - Composite magnet and production method therefor, antenna, and communication device - Google Patents

Abstract

The present invention provides a composite magnet made by dispersing plate-shaped magnetic particles into an insulating material, a production method therefor, an antenna provided with the composite magnet, and a communication device provided with the antenna. The composite magnet is characterized in that the average thickness of the plate-shaped magnetic particles is 0.01 μm to 0.5 μm, the average diameter is 0.05 μm to 10 μm, and the average aspect ratio (major axis/thickness) is 5 or more.

Description

COMPOSITE MAGNETIC MATERIAL AND METHOD FOR MANUFACTURING THE SAME

The present invention relates to a composite magnetic body, a manufacturing method thereof, an antenna, and a communication device, and more particularly, a high-frequency circuit board, a high-frequency electronic component, a magnetic sheet, and an electromagnetic wave using an electromagnetic wave in a VHF band that is a frequency band from 70 MHz to 500 MHz. A composite magnetic body suitably used for a shielding sheet, a resin-bonded magnet, a magnetic recording medium, an antenna, and the like and having a real part μr ′ having a high complex permeability, a manufacturing method thereof, and an antenna including the composite magnetic body, In addition, the present invention relates to a communication device provided with this antenna. Furthermore, the present invention relates to a monopole antenna loaded with the composite magnetic body that can be used in a portable terminal at 160 MHz to 222 MHz.
The present application is filed in Japanese Patent Application No. 2010-266903 filed in Japan on November 30, 2010, Japanese Patent Application No. 2011-064310 filed in Japan on March 23, 2011, and filed in Japan on April 25, 2011. Japanese Patent Application No. 2011-097157, Japanese Patent Application No. 2011-122440 filed in Japan on May 31, 2011, Japanese Patent Application No. 2011-167077 filed in Japan on July 29, 2011, July 29, 2011 Japanese Patent Application No. 2011-167078 filed in Japan, Japanese Patent Application No. 2011-254169 filed in Japan on November 21, 2011, Japanese Patent Application No. 2011-257615 filed in Japan on November 25, 2011, November 2011 Claim priority based on Japanese Patent Application No. 2011-257616 filed in Japan on May 25, the contents of which are incorporated herein by reference.

A magnetic material is known to be used as a composite magnetic material mixed and dispersed in an insulating material such as an organic polymer material because of its properties against electromagnetic waves, productivity, and ease of use.
This magnetic material is used for electronic components mounted on electronic devices, magnetic sheets, electromagnetic interference suppression sheets, electric products such as motors and transformers, and magnetic recording media such as video tapes and floppy (registered trademark) disks.

In recent years, with the increase in speed and density of information communication devices, there is a strong demand for downsizing and low power consumption of electronic components, circuit boards and antennas mounted on electronic devices, especially antennas for portable information devices. ing.
In general, the wavelength λg of the electromagnetic wave propagating in the substance is determined by the wavelength λo of the electromagnetic wave propagating in the vacuum, the real part εr ′ of the complex permittivity of the substance (hereinafter sometimes abbreviated as εr ′), and the actual complex permeability. Using the part μr ′ (hereinafter sometimes abbreviated as μr ′),
λg = λo / (εr ′ · μr ′) ^1/2 (1)
It can be expressed as. According to this equation (1), as εr ′ and μr ′ increase, the shortening rate of the wavelength λg increases. Therefore, by increasing εr ′ and μr ′ of the magnetic material constituting the electronic component, the circuit board, the antenna, etc., the shortening rate of the wavelength λg is increased, so that the electronic component, the circuit board, the antenna, etc. can be downsized. It becomes possible.

As a material with an increased wavelength shortening rate, a composite magnetic material in which magnetic particles are mixed and dispersed in an insulating material constituting an electronic component or a circuit board has been proposed (Patent Document 1). In this composite magnetic body, the wavelength shortening rate is increased by increasing μr ′.

By the way, when spherical magnetic particles are used for the composite magnetic body, the demagnetizing factor coefficient of each magnetic particle increases, and therefore it is generally difficult to increase μr ′ of the composite magnetic body. Are known.
Therefore, as the magnetic particles used for such applications, flat magnetic particles having a thickness of 10 μm or less are desired, and various aspect ratios (major axis / thickness) such as a flat shape, a scale shape, and a flake shape are large. Magnetic particles having various shapes have been proposed (see, for example, Patent Documents 2 and 3).

With such tabular magnetic particles, a high μr ′ is obtained in the plane direction with the lowest demagnetizing field coefficient, that is, the major axis direction. Therefore, in order to obtain a high μr ′ by effectively utilizing the effect of the demagnetizing factor, a composite magnetic material in which tabular magnetic particles are mixed and dispersed in an insulating material is used as an insulating material. It must be oriented in one direction.
As a method of orienting the flat magnetic particles, a method of passing a coating film containing flat magnetic fine particles formed on a substrate between the magnetic poles of a magnet (Patent Document 4), or a molding die incorporating a permanent magnet There has been proposed a method using the above (Patent Document 5).
In these methods, a resin is used as the insulating material, and the magnetic particles are oriented by applying a magnetic field in a state where the resin is fluid before being thermally cured or heated and melted.

By the way, in the conventional method for orienting flat magnetic particles described in Patent Document 4 and Patent Document 5, a magnetic field is applied by applying a magnetic field in a state where the resin is fluid before heat curing or by heat melting. Even if the particles are oriented, there is a problem that the obtained composite magnetic body has a small μr ′.

In addition, although the μr ′ of the individual soft magnetic tabular magnetic particles themselves is higher than that of the hard magnetic tabular magnetic particles having a large coercive force, the conventional magnetic field application method has a small soft magnetic force. The tabular magnetic particles have a problem that the orientation is poor and the μr ′ obtained as a whole of the composite magnetic material is small. In particular, when a composite magnetic body having a thickness of 100 μm or more is manufactured, there is a problem in that good μr ′ cannot be obtained.

In recent years, in the VHF band of 90 to 220 MHz, from the viewpoint of effective use of radio resources, a change from the use for analog TV to another use is planned. Among these applications, portable information terminals are particularly promising. However, in this portable information terminal, it is difficult to reduce the size of the antenna due to the long wavelength of the radio wave in the VHF band. An antenna or an earphone cord must be used as an antenna.

On the other hand, since the use of portable information terminals has expanded from calls to communications other than calls, the portable information terminals can be received even when they are placed in bags or pockets. Built into the terminal is a must. Therefore, there is a demand for a magnetic material that has a large wavelength shortening effect and can reduce the size of the VHF band antenna.
However, when a conventional magnetic material is applied to a VHF band antenna, an eddy current is generated on the surface of the magnetic material, and the magnetic material has a magnetic permeability in order to generate a magnetic field in a direction that cancels the change in the applied magnetic field. There was a problem that apparently decreased.
Further, since an increase in eddy current causes energy loss due to Joule heat, it is difficult to use a magnetic material as a material for an antenna, an electronic component or the like.

Patent Document 6 is a composite in which spherical or flat magnetic powder is dispersed in an insulating material. The real part μr ′ of the complex permeability at 1 GHz is larger than 1, and the loss tangent tan δμ of the complex permeability. A composite magnetic body having a value of 0.1 or less (hereinafter sometimes abbreviated as tan δμ) has been proposed.
According to this composite magnetic body, it is possible to avoid deterioration of magnetic characteristics due to eddy current, and it is possible to reduce loss even in a frequency band of 500 MHz to 1 GHz.
On the other hand, high frequency ferrites have been proposed as magnetic materials that can be used in the VHF band.

However, although the composite magnetic material proposed in Patent Document 6 can reduce the magnetic characteristics due to eddy currents and reduce the loss in the frequency band of 500 MHz to 1 GHz, the loss tangent increases at a frequency lower than 500 MHz. In particular, tan δμ at 100 MHz is 0.1 or more. Therefore, even if this composite magnetic material is applied to a VHF band antenna, there is a problem that it is difficult to further downsize the antenna.

In addition, although the high frequency ferrite can be used in the VHF band, the VHF band is a frequency band in which the influence of resonance loss is noticeable, so that the frequency dependence of μr ′ is large and the circuit design is difficult. There was a point.
Furthermore, since ferrite is a ceramic, there is a problem that shape workability and mechanical reliability are poor, and therefore, when applied to a portable information terminal, various limitations occur, which is not preferable.

Incidentally, the characteristic impedance Z _g of material with a characteristic impedance Z ₀ of the vacuum, can be represented by the following formula (2).
Z _g = Z ₀ · (μr ′ / εr ′) ^1/2 (2)
According to Equation (2), the smaller the difference between the values of εr ′ and μr ′, the smaller the difference between the characteristic impedance Z _{0 in} vacuum and the characteristic impedance Z _g of the composite magnetic material. On the other hand, the characteristic impedance of the space where radio waves fly is almost the same value as the vacuum characteristic impedance Z ₀ , so that the smaller the difference between the values of εr ′ and μr ′, the lower the power loss for impedance matching.
Further, when the wavelength of the electromagnetic wave is shortened according to the equation (1), the values of εr ′ and μr ′ may be increased, but the frequency at which transmission and reception can be performed when the difference between the value of εr ′ and the value of μr ′ is large. It is also known that the bandwidth is narrowed. Therefore, in order to transmit and receive a large amount of information in a wide frequency band, it is necessary that the difference between the value of εr ′ and the value of μr ′ is small.

Therefore, by dispersing spherical magnetic particles in an insulating material as a composite magnetic material for transmitting and receiving a large amount of information in a wide frequency band while suppressing downsizing and power loss of electronic components and electronic devices, Composite magnetism in which μr ′ at a frequency of 1 GHz is 5 or more, (μr ′ · εr ′) − 1/2 is 0.2 or less, and (μr ′ / εr ′) 1/2 is 0.5 or more and 1 or less. A body has been proposed (Patent Document 7).

However, since the composite magnetic body described in Patent Document 7 uses spherical magnetic body particles, the demagnetizing field coefficient of each magnetic body particle becomes large, and therefore the obtained composite magnetic body has a sufficient μr ′. However, even if power loss due to impedance matching can be suppressed, there is a problem in that electronic components and electronic devices are not sufficiently miniaturized.

On the other hand, in the composite magnetic body described in Patent Document 8, since a metal material having high conductivity is used as the tabular magnetic body particles, the value of μr ′ of the composite magnetic body also increases. Since the interface with the insulating material has a capacitance, the value of εr ′ becomes larger than that and there is a problem that power loss due to impedance matching increases.
This power loss is, for example, an output loss of electromagnetic waves when the antenna transmits and receives electromagnetic waves, and the radiation efficiency, which is the most important performance of the antenna, is reduced. In addition, since the difference between μr ′ and εr ′ is enlarged, the frequency band in which the antenna can transmit and receive is also narrowed.

Furthermore, in most magnetic particles, μr ′ is smaller than εr ′ (μr ′ <εr ′). Therefore, even if μr ′ of the composite magnetic material itself is increased by improving the magnetic particles, εr ′ is There is a problem that it becomes larger than that, electronic components and electronic devices cannot be reduced in size, power loss cannot be suppressed, and further, it is not possible to widen the frequency range of antenna transmission and reception. there were.

Such a problem is a serious problem in antennas used in portable information devices such as portable telephones, portable information terminals, and multifunctional portable information devices, which have a large demand for downsizing. Become.
In particular, multi-functional portable information terminals such as smartphones that have recently become widely used generate a strong electric field from a display unit that is approximately the same size as the housing, and therefore this display unit blocks electromagnetic waves. Become. Therefore, the antenna needs to be provided at a position that does not overlap with the display or at a position spaced from the display. However, the position where the antenna can be installed is limited within the housing, and is an extremely narrow area.

On the other hand, one-segment broadcasting and multimedia broadcasting used in portable information devices require reception of electromagnetic waves in a wide wavelength band because the wavelengths of electromagnetic waves used are long. Conventionally, a small antenna in a housing cannot provide sufficient reception performance. Therefore, for the purpose of receiving these broadcasts, the antenna portion can be extended and extended to be several times longer than the housing size. There has been proposed a portable information device in which a whip antenna capable of being installed is installed outside a casing. However, even when this whip antenna is used, if the portable information device is put in a bag or pocket, the whip antenna cannot be extended. There was a problem that it was difficult.

In recent years, the lowest frequency band of electromagnetic waves used in mobile terminals is 470 MHz to 770 MHz for terrestrial digital broadcasting (one seg) for mobiles. In Japan, it is planned to use 207 MHz to 222 MHz as a multimedia broadcast for portable terminals. In Korea, the frequency band of 180 MHz to 210 MHz is about to be used for digital broadcasting.

The antenna used for such a mobile terminal needs to be a small antenna that can be mounted on the mobile terminal. However, in order for the antenna to resonate, an antenna conductor having a length of ¼ of the wavelength is required, and a band having a low frequency such as the 160 MHz to 222 MHz band and a long wavelength is mounted on the portable terminal. Had the problem that the antenna was too large.

In order to solve the above problem, Patent Document 9 proposes a method of miniaturizing a magnetic antenna by using a wavelength having a shortening effect by using a ferrite having a high magnetic permeability.

However, in the technique described in Patent Document 9, the ceramic material such as ferrite has a small magnetic permeability from 160 MHz to 222 MHz, so the wavelength shortening effect is small, and the antenna cannot be sufficiently miniaturized. Furthermore, since the ceramic material is inferior in workability, there is a problem that the shape that can be used is limited.

JP 2004-087627 A JP-A-63-35701 JP-A-1-188606 Japanese Patent Laid-Open No. 57-127931 JP 2000-141392 A JP 2008-181905 A JP 2010-103427 A JP 2008-263098 A JP 2009-159244 A

The present invention has been made in view of the above circumstances, and can be applied to a frequency band from 70 MHz to 500 MHz. Further, the real part μr ′ of the complex permeability in this frequency band is large, and the complex permeability. An object of the present invention is to provide a composite magnetic body having flat magnetic particles such that the loss tangent tan δμ of the above becomes 0.1 or less, a manufacturing method thereof, an antenna, and a communication device.

Further, when downsizing electronic components and electronic devices, the real part μr ′ of the complex permeability is sufficiently large in accordance with the downsizing, and the value of the real part μr ′ of the complex permeability and the real value of the complex dielectric constant are used. The difference between the value of the portion εr ′ is reduced, and as a result, the electronic component and the electronic device can be downsized, and at the same time, the composite magnetic body capable of suppressing the power loss due to impedance matching and widening the band, and the antenna including the same An object of the present invention is to provide a communication device.

Another object of the present invention is to provide a composite magnetic body in which the real part μr ′ of the complex permeability is increased when the flat magnetic particles are well oriented in the resin, a manufacturing method thereof, an antenna, and a communication device. To do.

It is another object of the present invention to provide a small monopole antenna that can be applied to a low frequency band such as 160 MHz to 222 MHz and can be mounted on a portable terminal.

As a result of intensive studies to solve the above problems, the present inventors have obtained the following knowledge.
Flat magnetic particles having an average thickness of 0.01 μm to 0.5 μm, an average major axis of 0.05 μm to 10 μm, and an average aspect ratio (major axis / thickness) of 5 or more were dispersed in an insulating material. In the case of a composite magnetic body, the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz of the composite magnetic body is set to be larger than 1, and the loss tangent tan δμ of the complex permeability is set to 0.1 or less. be able to. That is, the present inventors have found that this composite magnetic body can be applied to a VHF band antenna, and as a result, it is possible to further reduce the size of the antenna and incorporate the antenna into a portable information terminal.

Further, in a composite magnetic body in which tabular magnetic particles are dispersed in an insulating material, when the amount of tabular magnetic particles is small, it is easy to disperse uniformly in the insulating material. As the number of the tabular magnetic particles increases, a space is generated between the tabular magnetic particles due to the entanglement or aggregation of the tabular magnetic particles, and it becomes difficult for the insulating material to enter the space. As a result, pores are generated in the obtained composite magnetic material. Further, when the tabular magnetic particles are oriented in one direction, the interval between the tabular magnetic particles arranged in parallel to each other is extremely narrow, making it difficult for the insulating material to enter this narrow space, As a result, pores are generated in the obtained composite magnetic body.

Therefore, when the tabular magnetic particles are dispersed in the insulating material, the value of εr ′ is almost increased although the value of μr ′ is increased by reducing the pores generated between the tabular magnetic particles. As a result, it was found that the difference between the value of μr ′ and the value of εr ′ can be reduced.

In addition, when a conventional bisphenol type epoxy resin and tabular magnetic particles are mixed as an insulating material, the resulting molding material has a functional group of the epoxy resin adsorbed on the surface of the tabular magnetic particles, and a polymer chain is not present. It surrounds the periphery of the magnetic particles and becomes intertwined for a long time. In such a molding material in which the polymer chains are long entangled, the polymer chains may be sterically hindered and the orientation of the tabular magnetic particles may be hindered.
Therefore, in order to improve the fluidity of the tabular magnetic particles, even if the amount of the solvent in the molding material is increased to make the viscosity low macroscopically, the influence of the steric hindrance of the polymer chain is still large, and the tabular shape The orientation of the magnetic particles will be hindered.
On the other hand, if the polymer chain is shortened in order to reduce the influence of steric hindrance of the polymer chain, the condensation or bonding reaction between the polymer chains becomes insufficient, and as a result, the mechanical strength of the resulting composite magnetic material In some cases, the shape may not be maintained, and the shape may not be maintained, and cannot be used for electronic components, circuit boards, and the like.

Therefore, in order to reduce the influence of the steric hindrance of the polymer chain, by using a resin having a cyclic structure in the main chain that is flat and hardly entangled with the tabular magnetic particles, the orientation of the tabular magnetic particles by applying a magnetic field Found to improve. Furthermore, it was obtained by forming many bonds even when the polymer chain is short, by using a resin having a functional group that polymerizes by a monomer unit, rather than a functional group that polymerizes only at the terminal. It has been found that the mechanical strength of the composite magnetic material is improved and the shape can be easily maintained.

Moreover, if a resin excellent in flexibility and stretchability is added to the resin having the above-mentioned cyclic structure in the main chain which is not easily entangled with the flat magnetic particles, the resin enters the gap between the flat magnetic particles. As a result, the real part μr ′ of the complex magnetic permeability of the composite magnetic body can be further improved, the peelability of the composite magnetic body from the base material can be further improved, and a composite magnetic body excellent in productivity can be obtained. I found.

Furthermore, when a magnetic material is applied by molding a molding material in which the resin and the flat magnetic particles are mixed, the magnetic field is applied once or a plurality of times so that the lines of magnetic force are substantially parallel to the surface of the molded body. It has been found that the real part μr ′ of the complex magnetic permeability of the composite magnetic material is improved by applying it twice.

Also, it was found that the antenna can be reduced in size by covering the conductor of the monopole antenna with the above composite magnetic material.

That is, the present invention relates to the following.

(1) A composite magnetic material obtained by dispersing tabular magnetic particles in an insulating material,
The flat magnetic particles have an average thickness of 0.01 μm or more and 0.5 μm or less, an average major axis of 0.05 μm or more and 10 μm or less, and an average aspect ratio (major axis / thickness) of 5 or more. Composite magnetic material.
(2) The real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is greater than 1, and the loss tangent tan δμ of the complex permeability is 0.1 or less. Composite magnetic material.
(3) The real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is larger than 7, and the loss tangent tan δμ of the complex permeability is 0.1 or less. Composite magnetic material.
(4) The real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is greater than 10, and the loss tangent tan δμ of the complex permeability is 0.1 or less. Composite magnetic material.
(5) The flat magnetic particles include aluminum (Al), chromium (Cr), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), niobium (Nb), and molybdenum (Mo). The composite magnetic material according to (1) above, which is an iron-nickel alloy containing one or more metal elements selected from the group consisting of indium (In) and tin (Sn).
(6) The tabular magnetic particles are formed by deforming and fusing the spherical magnetic particles by applying mechanical stress to the spherical magnetic particles having an average particle diameter of 0.5 μm or less. The composite magnetic material according to (1) above.
(7) The real part μr ′ of the complex permeability in the frequency band from 90 MHz to 220 MHz is greater than 1, and the loss tangent tan δμ of the complex permeability is 0.05 or less. Composite magnetic material.
(8) The composite magnetic body according to (1), wherein the porosity is 20% or less.
(9) The real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is 7 or more, the real part εr ′ of the complex permittivity is 15 or more, and (μr ′ · εr ′) ^−1/2 Is 0.1 or less and (μr ′ / εr ′) ^1/2 is 0.5 or more and 1 or less, the composite magnetic body according to (8) above.
(10) The loss tangent tan δμ of the complex permeability in the frequency band from 70 MHz to 500 MHz is 0.05 or less, and the loss tangent tan δε of the complex permittivity is 0.1 or less. Magnetic material.
(11) The composite magnetic body according to (1), wherein the insulating material includes a first resin having a cyclic structure in a main chain and having a functional group that is polymerized in a monomer unit.
(12) The composite magnetic body according to (11), wherein the resin is a thermosetting resin.
(13) The composite magnetic body according to (11), wherein the resin is an epoxy resin.
(14) The composite magnetic body according to (11), wherein the resin is a dicyclopentadiene type epoxy resin.
(15) The composite according to (11), wherein an angle between the orientation direction of the tabular magnetic particles in the resin and the major axis direction of the tabular magnetic particles is 20 ° or less. Magnetic material.
(16) The composite magnetic body according to (11), wherein the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is 7 or more.
(17) The composite magnetic body according to (11), further including a second resin, which is a resin that imparts flexibility to the first resin.
(18) The composite magnetic body according to (17), wherein the second resin is an epoxy resin having at least one of a bisphenol A skeleton and a bisphenol F skeleton.
(19) The composite magnetic body according to (17), wherein the second resin is an epoxy resin containing two or more epoxy groups in one molecule and having an ether skeleton.
(20) The composite magnetic material according to (17), wherein the second resin is an epoxy resin having any one of propylene glycol-added bisphenol A skeleton and ethylene glycol-added bisphenol A skeleton body.
(21) The composite magnetic body according to (17), wherein the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is 7 or more.
(22) A method for producing a composite magnetic material according to (1) to (21), wherein a spherical magnetic particle having an average particle diameter of 0.5 μm or less is dispersed in a solution containing a surfactant. And the dispersion medium is filled in a sealable container so that the total volume of the slurry and the dispersion medium is the same as the volume in the container, and the slurry is stirred together with the dispersion medium in a sealed state, A first step in which the spherical magnetic particles are deformed and fused to form tabular magnetic particles, and the tabular magnetic particles are dispersed and mixed in a solution in which an insulating material is dissolved in a solvent, and then molded. A third step including a second step as a material, a molding step of molding or applying the molding material on a substrate to obtain a molded body, and a drying / curing step of drying and curing the molded body; Of a composite magnetic material characterized by comprising Production method.
(23) The method for producing a composite magnetic body according to (22), wherein the insulating material is a resin having a cyclic structure in the main chain and a functional group that is polymerized in a monomer unit.
(24) In the third step, after the forming step, a magnetic field is applied to the obtained formed body to perform an aligning step of aligning the flat magnetic particles in the formed body in one direction, and then The method for producing a composite magnetic body according to (22), wherein a drying / curing step is performed.
(25) An antenna comprising the composite magnetic body according to any one of (1) to (21).
(26) A communication apparatus comprising the antenna according to (25).
(27) A monopole antenna, wherein the antenna conductor is covered with the composite magnetic material according to (1).
(28) The monopole antenna according to (27), wherein the composite magnetic body has a real part μr ′ of complex permeability in a frequency band from 160 MHz to 222 MHz being 3 or more.
(29) The monopole antenna according to (28), wherein a coating thickness of the composite magnetic body is 2.4 mm or more and 10 mm or less.
(30) The monopole antenna according to (27), wherein the composite magnetic body has a real part μr ′ of complex permeability in a frequency band from 160 MHz to 222 MHz of 6 or more.
(31) The monopole antenna according to (30), wherein a coating thickness of the composite magnetic body is 1.2 mm or more and 10 mm or less.
(32) The monopole antenna according to (27), wherein the length of the antenna conductor is 200 mm or less.

According to the composite magnetic body of the present invention, a plate shape having an average thickness of 0.01 μm or more and 0.5 μm or less, an average major axis of 0.05 μm or more and 5 μm or less, and an average aspect ratio (length / thickness) of 5 or more. Since magnetic particles are used, the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz can be larger than 1 and the loss tangent tan δμ of the complex permeability can be 0.1 or less. The wavelength shortening rate can be increased.
Therefore, if this composite magnetic body is applied to a VHF band antenna, generation of eddy currents on the surface of the composite magnetic body can be prevented, μr ′ can be prevented from being lowered, and the antenna can be further reduced in size. Can be achieved.
Therefore, if this composite magnetic body is applied to a VHF band antenna or electronic component, the antenna or electronic component can be further reduced in size.

According to the composite magnetic body of the present invention, since the porosity of the composite magnetic body having the above plate-like magnetic particles is set to 20% or less, the value of the real part μr ′ of the complex permeability increases, but the complex dielectric constant The value of the real part εr ′ can be made almost unchanged. Therefore, the difference between the value of the real part μr ′ of the complex magnetic permeability and the value of the real part εr ′ of the complex dielectric constant can be reduced. As a result, an electronic component or electronic device to which the composite magnetic body is applied can be reduced. The size can be reduced, and power loss due to impedance matching can be suppressed.

According to the composite magnetic body of the present invention, since the plate-like magnetic body particle and the first resin having a cyclic structure in the main chain and having a functional group that is polymerized in a monomer unit are contained, Since it has a structure that is flat and hardly entangled with the tabular magnetic particles, the influence of steric hindrance by the resin on the tabular magnetic particles can be reduced. Therefore, a composite magnetic body having a good orientation of the tabular magnetic particles and a high real part μr ′ of complex permeability can be obtained.
Furthermore, since a resin having a functional group that is polymerized in monomer units is used, the resin bond becomes strong, and it is possible to have sufficient mechanical strength as a molded body for use in electronic parts and the like.

According to the composite magnetic body of the present invention, the flat magnetic particles, the first resin having a cyclic structure in the main chain and having a functional group that is polymerized in a monomer unit, and the first resin are flexible. The first resin having a cyclic structure in the main chain and having a functional group that polymerizes in monomer units is a three-dimensional structure formed by the resin with respect to the tabular magnetic particles. The influence of the failure can be reduced. Therefore, the orientation of the tabular magnetic particles in one direction can be improved, and a composite magnetic body having a high real part μr ′ of complex permeability can be easily obtained.
Since the second resin imparts flexibility to the first resin, it is possible to improve the flexibility and stretchability of the composite magnetic body itself, and as a result, the composite magnetism having excellent productivity. You can get a body.

According to the method for producing a composite magnetic body of the present invention, a container capable of sealing a slurry and a dispersion medium in which spherical magnetic particles having an average particle diameter of 0.5 μm or less are dispersed in a solution containing a surfactant. The total volume of the slurry and the dispersion medium is filled so as to be the same as the volume in the container, and the slurry is stirred together with the dispersion medium in a sealed state to deform the spherical magnetic particles. And a first step of fusing to form tabular magnetic particles, and a second step of dispersing and mixing the tabular magnetic particles in a solution in which an insulating material is dissolved in a solvent to obtain a molding material; The molding material is molded or applied onto a base material to obtain a molded body, and the third process includes a drying / curing process for drying and curing the molded body. Up to That .mu.r 'is large and the loss tangent tanδμ the complex permeability can also be readily prepared 0.1 following composite magnetic body.

In addition, when a resin having a cyclic structure in the main chain and a functional group that polymerizes in monomer units is used as the insulating material, the orientation of the tabular magnetic particles is good and the real part of the complex permeability A composite magnetic body having a high μr ′ can be easily produced.
Furthermore, in the third step, after the molding step, an orientation step is performed in which a magnetic field is applied to the obtained molded body to orient the flat magnetic particles in the molded body in one direction, and then the drying and drying are performed. When performing the curing step, it is possible to easily produce a composite magnetic material in which the orientation of the tabular magnetic particles is better and the real part μr ′ of the complex permeability is higher.

According to the antenna of the present invention, since the composite magnetic body is provided, by using the composite magnetic body having a high real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz, the wavelength is less than ¼ of the wavelength. Since the antenna conductor can be shortened, the entire antenna can be reduced in size. Therefore, a further miniaturized antenna can be provided.

Furthermore, when a composite magnetic body having a porosity of 20% or less is provided, the radiation efficiency can be improved. Therefore, it is possible to provide a small antenna that can suppress power loss due to impedance matching, is small, has high radiation efficiency, and can be used in a wide band from 70 MHz to 500 MHz.

In addition, when the insulating material includes a composite magnetic body including a first resin having a cyclic structure in the main chain and having a functional group that is polymerized in a monomer unit, or as the insulating material, the first resin and When a composite magnetic body containing a second resin that imparts flexibility to the first resin is provided, a higher μr ′ can be obtained, so that a more miniaturized antenna can be provided.

According to the communication device of the present invention, since the antenna is provided, the communication device as a whole can be reduced in size by using a miniaturized antenna. Therefore, a further miniaturized communication apparatus can be provided.

Further, when the antenna loaded on the composite magnetic body having a porosity of 20% or less is provided, the communication apparatus as a whole can be obtained by using a small antenna having high radiation efficiency and usable in a wide band. Can be reduced in size and communication performance can be improved. Therefore, it is possible to provide a communication device that is further downsized and can be used in a wide band from 70 MHz to 500 MHz.

According to the monopole antenna of the present invention, since the antenna conductor is coated with the composite magnetic material, the antenna conductor can be made shorter than ¼ of the wavelength, so that radio waves in a low frequency band of 160 MHz to 222 MHz can be transmitted. A monopole antenna that is small enough to be mounted on a portable terminal while being able to transmit, receive, or transmit / receive can be obtained.

It is a figure which shows a mode that the slurry containing a spherical magnetic particle and dispersion medium are stirred at high speed using an open container. It is a figure which shows a mode that the slurry and dispersion medium containing a spherical magnetic particle are stirred at high speed using an airtight container. It is a schematic block diagram which shows the orientation apparatus for implementing the orientation method A of this invention. It is a schematic block diagram which shows the orientation apparatus for implementing the orientation method B of this invention. It is a schematic block diagram which shows the orientation apparatus for implementing the orientation method C of this invention. It is a schematic diagram which shows operation | movement of the orientation apparatus for enforcing the orientation method C of this invention. It is a schematic block diagram which shows the orientation apparatus for implementing the orientation method D of this invention. It is a schematic diagram which shows the electric power feeding method of the monopole antenna which is an example of the antenna of one Embodiment of this invention. It is a perspective view which shows an example of the kind of portable telephone of the communication apparatus of one Embodiment of this invention. It is a perspective view which shows another example of a kind of portable telephone of the communication apparatus of one Embodiment of this invention. It is a perspective view which shows another example of a kind of portable telephone of the communication apparatus of one Embodiment of this invention. It is a perspective view which shows another example of a kind of portable telephone of the communication apparatus of one Embodiment of this invention. It is a perspective view which shows an example of the portable telephone with a kind of protective cover of the communication apparatus of one Embodiment of this invention. It is a top view which shows another example of the portable telephone with a kind of protective cover of the communication apparatus of one Embodiment of this invention. It is sectional drawing which follows the AA line of FIG. It is a schematic diagram which shows the structure and electric power feeding method of the monopole antenna of this embodiment. It is sectional drawing in the position which follows the AA line of FIG. 16A. It is a figure which shows the complex magnetic permeability and loss tangent of the composite magnetic body of Example 1 of this invention. It is a scanning electron microscope (SEM) image which shows the structure of the composite magnetic body of Example 1 of this invention. It is a figure which shows the complex magnetic permeability and loss tangent of the composite magnetic body of the comparative example 1. 3 is a scanning electron microscope (SEM) image showing the structure of the composite magnetic body of Comparative Example 1. It is a figure which shows the real part (micro | micron | mu) r 'of the complex magnetic permeability in each frequency of the composite magnetic body of Example 3 of this invention, and the loss tangent tan-deltamicro of a complex magnetic permeability. It is a figure which shows the real part (epsilon) r 'of the complex dielectric constant in each frequency of the composite magnetic body of Example 3 of this invention, and the loss tangent tan-deltaepsilon of a complex dielectric constant. It is a figure which shows the real part (micro | micron | mu) r 'of the complex magnetic permeability in each frequency of the composite magnetic body of Example 4 of this invention, and the loss tangent tan-deltamicro of a complex magnetic permeability. It is a figure which shows the real part (epsilon) r 'of the complex dielectric constant in each frequency of the composite magnetic body of Example 4 of this invention, and the loss tangent tan-deltaepsilon of a complex dielectric constant. FIG. 18 is a diagram showing the complex permeability real part μr ′ and the complex permeability loss tangent tan δμ in the frequency band of 10 to 1000 MHz of the composite magnetic body of Example 18 of the present invention. FIG. 26 is a diagram showing a real part μr ′ of complex permeability and a loss tangent tan δμ of complex permeability at each frequency of the composite magnetic body of Example 25. It is a figure which shows the relationship between the antenna length which resonates with the coating thickness of a composite magnetic body.

The composite magnetic body according to the present invention, a manufacturing method thereof, an antenna, and a mode for carrying out a communication device will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

[First composite magnetic body]
The composite magnetic body of the present embodiment is a composite magnetic body obtained by dispersing tabular magnetic particles in an insulating material, and the average thickness of the tabular magnetic particles is 0.01 μm or more and 0.5 μm or less, The composite magnetic body has an average major axis of 0.05 μm or more and 10 μm or less, and an average aspect ratio (major axis / thickness) of 5 or more.

The average thickness and the average major axis are the thickness and major axis (maximum length in the grain) of each of the plurality of tabular magnetic particles, for example, the thickness of each of the tabular magnetic particles of 100 or more, preferably 500 or more. It can be determined by measuring the major axis and calculating the average value of the thickness and major axis.
In addition, the average aspect ratio (major axis / thickness) of the tabular magnetic particles is the same as the above in terms of the major axis and thickness of each of the plurality of tabular magnetic particles, for example, 100 or more, preferably 500 or more. By measuring the major axis and thickness of each magnetic particle, the aspect ratio (major axis / thickness) of each tabular magnetic particle is determined, and the average value of these aspect ratios (major axis / thickness) is calculated. Desired.
The average thickness of the tabular magnetic particles is 0.01 μm or more and 0.5 μm or less, preferably 0.012 μm or more and 0.3 μm or less. The average major axis is 0.05 μm or more and 10 μm or less, preferably 0.5 μm or more and 5 μm or less.
Here, when the average thickness is less than 0.01 μm, it is difficult to manufacture, which will be described later, and handling becomes difficult. Therefore, when the average thickness exceeds 0.5 μm, the particles are fused. This is not preferable because the resulting thickness variation causes the loss tangent tan δμ of the complex permeability in the VHF band to increase.

The average aspect ratio (major axis / thickness) of the tabular magnetic particles is preferably 5 or more, more preferably 7 or more.
Here, if the average aspect ratio (major axis / thickness) is smaller than 5, the demagnetizing factor of the tabular magnetic particles is increased, and as a result, the μr ′ of the composite magnetic material is lowered, which is not preferable.

The reason why the shape of the tabular magnetic particles is limited to the above range is as follows.
The magnitude of the demagnetizing field in the magnetic particles depends on the shape of the magnetic particles. For example, when the magnetic particles are spherical, since the demagnetizing field is isotropic, the magnetic permeability obtained is isotropic, and it is difficult to obtain excellent magnetic properties in the high frequency region. On the other hand, when the shape of the magnetic particles is within the above range, the demagnetizing field in the direction parallel to the flat plate surface is remarkably reduced, and thus the obtained μr ′ is increased.
Therefore, by using the flat magnetic particles, the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is larger than 1, and the loss tangent tan δμ of the complex permeability is 0.1 or less. A composite magnetic body can be obtained.
The real part μr ′ of the complex permeability is preferably 5 or more, and more preferably 10 or more.

Here, the reason why the real part μr ′ of the complex permeability and the loss tangent tan δμ of the complex permeability are limited to the above range is that this range can reduce the wavelength of the electromagnetic wave and the magnetic loss due to the eddy current. This is because the energy loss is reduced and the energy loss is reduced.
In this composite magnetic body, more preferably, the real part μr ′ of the complex permeability in the frequency band from 90 MHz to 220 MHz is larger than 1, and the loss tangent tan δμ is 0.05 or less.

The magnitude of the energy loss can be expressed by an imaginary part μr ″ (hereinafter sometimes abbreviated as μr ″) of the complex permeability shown in the following formula (3).
μr ″ = μr ′ × tan δμ (3)
Here, since the imaginary part μr ″ of the complex permeability is preferably 0.5 or less, from the above equation (3), when μr ′ is 10, tan δμ is 0.05 or less. Further, when μr ′ is 15, tan δμ is preferably 1/30 or less.

The composition of the tabular magnetic particles is Fe-Ni alloy such as Permalloy (trade name), Fe-Ni-Mo alloy such as Supermalloy (trade name), and Fe-Si-Al alloy such as Sendust (trade name). , Fe—Si alloy, Fe—Co alloy, Fe—Cr alloy, Fe—Cr—Si alloy and other high magnetic permeability alloys such as aluminum (Al), chromium (Cr), manganese (Mn), cobalt (Co), An alloy to which a metal element such as copper (Cu), zinc (Zn), niobium (Nb), molybdenum (Mo), indium (In), tin (Sn) is added is preferable.

The addition amount of the metal element in the tabular magnetic particles is preferably 0.1% by mass to 90% by mass, more preferably 1% by mass to 12% by mass, and more preferably 1% by mass to 5% by mass. % Or less is more preferable.
Here, the reason why the amount of the metal element added is limited to the above range is that if the amount of the metal element added is less than 0.1% by mass, sufficient plastic deformation ability cannot be imparted to the magnetic particles, On the other hand, when the addition amount exceeds 90% by mass, the magnetic moment of the metal element itself is small, so that the saturation magnetization of the entire magnetic particle is small, and as a result, the obtained μr ′ is also small.

In particular, aluminum (Al), chromium (Cr), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), niobium (Nb), molybdenum (Mo) in that high μr ′ can be obtained. An iron-nickel alloy containing 1% by mass to 5% by mass of one or more metal elements selected from the group consisting of indium (In) and tin (Sn) is preferable.

The insulating material is not particularly limited as long as it is an insulating material. However, when the composite magnetic body of the present embodiment is used as an antenna for a mobile phone or an antenna for a portable information terminal, the mechanical strength is high and the hygroscopic property is high. It is preferable that it is low and it is excellent in shape workability. Examples of such an insulating material include polyimide resin, polybenzoxazole resin, polyphenylene resin, polybenzocyclobutene resin, polyarylene ether resin, polysiloxane resin, epoxy resin, polyester resin, fluorine resin, polyolefin resin, polycyclohexane. Thermosetting resins or thermoplastic resins such as olefin resins, cyanate resins, polyphenylene ether resins, norbornene resins, ABS resins, and polystyrene resins are preferably used. These resins may be used alone or in combination of two or more.
Especially, as a thermosetting resin, the epoxy resin excellent in mechanical strength and shape workability is preferable, and a polyphenylene resin and an ABS resin are preferable as a thermoplastic resin.

[Method for producing first composite magnetic body]
In the method for producing a composite magnetic body of the present embodiment, a slurry and a dispersion medium obtained by dispersing spherical magnetic particles having an average particle diameter of 0.5 μm or less in a solution containing a surfactant are placed in a sealable container. The slurry is filled so that the total volume of the slurry and the dispersion medium is the same as the volume in the container, and the slurry is stirred together with the dispersion medium in a sealed state to deform and melt the spherical magnetic particles. A first step of forming tabular magnetic particles to be coated; a second step of dispersing and mixing the tabular magnetic particles in a solution obtained by dissolving an insulating material in a solvent to form a molding material; A molding step of molding or applying a molding material on a substrate to obtain a molded body, and a third step including a drying / curing step of drying and curing the molded body.

Hereinafter, each step will be described in detail.
<First step>
First, spherical magnetic particles having an average particle size of 0.5 μm or less are dispersed in a solution containing a surfactant to obtain a slurry.
The composition of the magnetic particles is exactly the same as the composition of the tabular magnetic particles described above.
As the surfactant, a surfactant containing an element such as nitrogen, phosphorus or sulfur that is compatible with the surface of the magnetic particles is preferable, and examples thereof include a nitrogen-containing block copolymer, a phosphate, and polyvinylpyrrolidone.

As the solvent for dissolving the surfactant, an organic solvent is preferable because it is necessary to prevent oxidation of the metal element contained in the magnetic particles, and in particular, nonpolar organic materials such as xylene, toluene, cyclopentanone, and cyclohexanone. A solvent is preferred.

Next, the slurry and the dispersion medium are filled in a sealable container so that the total volume of the slurry and the dispersion medium is the same as the volume in the container, and the slurry is stirred together with the dispersion medium in a sealed state. Then, spherical magnetic particles are deformed and fused together to form flat magnetic particles.

The dispersion medium must be harder than spherical magnetic particles, for example, metal spheres such as aluminum, steel (steel), stainless steel, and lead, and metal oxides such as alumina, zirconia, silicon dioxide, and titania. Spherical sintered body made of an inorganic oxide such as silicon nitride, spherical sintered body made of inorganic nitride such as silicon nitride, spherical sintered body made of inorganic carbide such as silicon carbide, soda glass, lead glass, high specific gravity glass, etc. In particular, zirconia, steel (steel), stainless steel and the like having a specific gravity of 6 or more are preferable from the viewpoint of efficiency.

Since the mechanical stress is applied to the spherical magnetic particles by an impact at the time of collision of the dispersion medium, the deformation and fusion properties of the spherical magnetic particles improve as the number of collisions of the dispersion medium increases. .
Thus, the smaller the average particle size of the dispersion medium, the more the number existing per unit volume, the greater the number of collisions, and the better the deformation and fusion properties. If it is too small, it will be difficult to separate the dispersion medium from the slurry. Therefore, the average particle size of the dispersion medium needs to be at least 0.03 mm or more, preferably 0.04 mm or more.
In addition, when the average particle size of the dispersion medium is too large, the number of collisions decreases, so that the deformation and fusion property between the spherical magnetic particles deteriorates. Therefore, the upper limit of the average particle diameter of the dispersion medium is 3.0 mm.

As the container that can be sealed, a sealed container that rotates the uniaxial rotating body such as a disk, a screw, and a blade at a high speed together with the slurry by rotating at high speed is preferable.
Since this hermetic container is a simple uniaxial rotation system, it is easy to increase the size and is advantageous for industrial production.
Note that the above-described sealable container may be provided with an inlet and an outlet for introducing and discharging the slurry into and from the container, and the slurry may be circulated in the sealed container. In this case, the dispersion medium is previously stored in a sealed container, and a slurry in which spherical magnetic particles, a surfactant, and a solvent are mixed is introduced from the inlet and filled so that there is no space in the container. The slurry discharged from the outlet may be charged again into the sealed container.

Here, the filling amount of the slurry and the dispersion medium into the above-mentioned closed container is the same as the volume in the closed container. In other words, the slurry and the dispersion medium are filled in the sealed container without gaps.
Here, the reason why the slurry and the dispersion medium are filled in the sealed container without any gap is as follows.

FIG. 1 is a diagram showing a state in which a slurry 153 containing spherical magnetic particles 152 and a dispersion medium 154 charged into an open container 151 having an open top are stirred at high speed by being rotated at high speed by a uniaxial rotating body 155. is there.
In this figure, when the uniaxial rotating body 155 rotates at a high speed, the liquid surfaces of the slurry 153 and the dispersion medium 154 have a mortar shape in which the vicinity of the central axis is low and the peripheral edge is high due to centrifugal force.
Since the mechanical stress applied to the slurry 153 including the spherical magnetic particles 152 and the dispersion medium 154 by the uniaxial rotating body 155 escapes into the mortar-shaped space, the entire inside of the open container 151 passes through the dispersion medium 154. The mechanical stress propagated to the spherical magnetic particles 152 becomes non-uniform, which causes a variation in the thickness of the obtained tabular magnetic particles.
Also, the magnetic particles that have become tabular magnetic particles in the vicinity of the bottom of the mortar-shaped space (near the central axis) are discharged into the mortar-shaped space together with the dispersion medium and are subjected to irregular impacts. There is a risk of chipping or the like. Such variation in thickness, cracking, and chipping of the magnetic particles are factors that increase the loss tangent tan δμ of the complex permeability in the VHF band.

FIG. 2 is a diagram showing that the slurry 153 containing the spherical magnetic particles 152 and the dispersion medium 154 charged in the sealed container 1511 are stirred at high speed by being rotated at high speed by the uniaxial rotating body 155.
In this figure, even when the uniaxial rotating body 155 rotates at a high speed, the inside of the sealed container 1511 is filled with the slurry 153 including the spherical magnetic particles 152 and the dispersion medium 154, so that it can be seen in the open container 151. There is no risk of creating a mortar-shaped space. Therefore, the mechanical stress applied to the slurry 153 including the spherical magnetic particles 152 and the dispersion medium 154 by the uniaxial rotating body 155 is uniformly applied to the spherical magnetic particles 152 via the dispersion medium 154 in the entire closed container 1511. There is no possibility that the thickness of the propagating and obtained tabular magnetic particles varies. Further, the magnetic particles having a flat plate shape are not subjected to an irregular impact, and there is no possibility that cracks, chips or the like are generated.

The number of rotations of the uniaxial rotating body 155 is determined by the size of the sealed container 1511. For example, in the case of a sealed container 1511 having an inner diameter of 120 mm, the flow rate of the slurry 153 containing the spherical magnetic particles 152 and the dispersion medium 154 near the inner wall of the sealed container 1511 is preferably 5 m / second or more, more preferably 8 m / second or more. is there.
If the internal volume of the sealed container 1511 is small, the spherical magnetic particles 152 may remain in the obtained flat magnetic particles. The remaining spherical magnetic particles 152 increase the magnetic loss or the orientation of the tabular magnetic particles due to contact between the spherical magnetic particles 152 or contact between the spherical magnetic particles 152 and the tabular magnetic particles. There is a risk of obstruction. Therefore, the tabular magnetic particles are preferably 90% by mass or more of the total amount of magnetic particles, more preferably 95% by mass or more, and still more preferably 99% by mass or more, and are substantially free of spherical magnetic particles 152. It is desirable.

Here, when the internal volume of the sealed container 1511 is small, the reason why the spherical magnetic particles 152 remain is that the mechanical stress such as the corner of the sealed container 1511 and the joint between the rotating body 5 and the sealed container 1511 is not sufficiently transmitted. This is probably because the dead space becomes relatively large. Therefore, when the internal volume of the sealed container 1511 is increased, the dead space is relatively reduced, and therefore, the mechanical stress is sufficiently transmitted to the spherical particles 2 to improve the deformation and fusion between spherical magnetic particles, As a result, the residual spherical magnetic particles 152 are reduced, and the substantially spherical magnetic particles 152 are eliminated.
Thus, the volume of the sealed container 1511 in which substantially spherical magnetic particles 152 do not remain is preferably 1 L or more, more preferably 5 L or more.
As described above, the spherical magnetic particles are deformed and fused by the mechanical stress applied by the uniaxial rotating body 155 to become flat magnetic particles.
Next, the tabular magnetic particles are separated from the dispersion medium and the solvent.

Note that a slurry drying step may be appropriately performed in consideration of the compatibility between the solvent used for producing the tabular magnetic particles and an insulating material to be mixed later.
Specifically, when the compatibility of the insulating material and the solvent used to produce the tabular magnetic particles is poor, the solvent is 4% by mass or less, preferably 2% by mass or less, more preferably It is preferable to dry-process until it becomes 1 mass% or less. On the other hand, when the compatibility of the insulating material and the solvent used to produce the tabular magnetic particles is good, the slurry state in which the tabular magnetic particles are dispersed in the solvent without performing the slurry drying step You may transfer to a 2nd process as it is.
The drying method is not particularly limited as long as the solvent can be removed from the slurry after preparing the flat magnetic particles, and examples thereof include heat drying, vacuum drying, freeze drying, and the like, but vacuum drying is preferable in terms of drying efficiency. In order to increase the drying efficiency, some solvent may be removed by a method such as solid-liquid separation before the drying step. As a solid-liquid separation method, a normal method such as a filtration operation such as a filter press or suction filtration, or a centrifugal separation operation using a decanter or a centrifuge may be used.

<Second step>
The flat magnetic particles described above are dispersed and mixed in a solution obtained by dissolving an insulating material in a solvent to obtain a molding material.
Here, as the insulating material, the same insulating material as described above can be used, and thus the description thereof is omitted.

The solvent is not particularly limited as long as it can dissolve the above insulating material. For example, alcohols such as methanol, ethanol, 2-propanol, butanol, octanol, ethyl acetate, butyl acetate , Ethyl lactate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, esters such as γ-butyrolactone, diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol mono Ethers such as butyl ether (butyl cellosolve), diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, acetone, methyl ethyl Preferred are ketones such as ketone, methyl isobutyl ketone, acetylacetone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene, and amides such as dimethylformamide, N, N-dimethylacetoacetamide and N-methylpyrrolidone. These solvents may be used alone or in combination of two or more.

The dispersion mixing method is not particularly limited, but it is preferable to use a stirring device such as a planetary mill, a sand mill, or a ball mill. What is necessary is just to adjust mixing conditions suitably so that tabular magnetic body particles may not aggregate.

<Third step>
The molding material is molded or applied onto a substrate to produce a molded body, and then the obtained molded body is dried and cured.
As the molding method, a known molding method, for example, a press method, a doctor blade method, an injection molding method or the like is suitable. A dry film can be produced by forming a sheet or film of any shape using this forming method.
When the composite magnetic body is a laminate, it is preferably formed into a sheet or film by the doctor blade method.
When it is necessary to adjust the viscosity, the molding material is molded after the solvent is volatilized and concentrated. If necessary, after the molding material is applied on the substrate, an orientation treatment for orienting the tabular magnetic particles in a direction parallel to the sheet or film by orientation of the magnetic field may be performed before drying.
As curing conditions, heat treatment or hot pressing is preferable in a reducing atmosphere or in a vacuum. Thereby, the composite magnetic body of this embodiment is obtained.

Note that the composite magnetic body of the present embodiment can also be obtained by molding a mixture of flat magnetic particles and thermosetting resin or thermoplastic resin by heat kneading.
As a heat-kneading method, a kneaded material mixed and dispersed by a known method such as a pressure kneader, a biaxial kneader, or a blast mill can be prepared. As a molding method of the kneaded product, a molded body can be produced by a known method such as hot press molding, extrusion molding, injection molding or the like. Among these methods, in order to orient the flat magnetic particles in the resin, hot press molding that extends in a planar shape is preferable. In order to adjust the viscosity at the time of stretching, it is also preferable to add a plasticizer and perform surface treatment of the tabular magnetic particles. If necessary, it is preferable to perform a treatment for orienting the tabular magnetic particles by the orientation of the magnetic field in a state where the fluidity is maintained by heating.

[Second composite magnetic body]
The composite magnetic body of the present embodiment is a composite magnetic body obtained by dispersing the flat magnetic particles in an insulating material, and the porosity of the composite magnetic body is 20% or less.

Here, the porosity of the composite magnetic body can be obtained by the following equation (4).
Porosity = (1−Measured density / Theoretical density) × 100 (4)
The theoretical density of this composite magnetic body is calculated in consideration of the mixing ratio of the tabular magnetic particles and the insulating material based on the theoretical density of the tabular magnetic particles and the theoretical density of the insulating material (≈ actually measured density). The
Further, as a method of calculating the theoretical density of the tabular magnetic particles, a method of calculating a lattice constant from an X-ray diffraction pattern of the tabular magnetic particles and calculating a theoretical density value based on the lattice constant and the crystal structure. There is.

On the other hand, as a method for calculating the measured density of the insulating material, for example, when the insulating material is resin, only the resin is cured and the outer dimensions and mass are measured, and the measured density is calculated from these measured values. There is.
In addition, as a method for calculating the actual density of the composite magnetic body, for example, there are a method of measuring the external dimensions and mass, a method of calculating the actual density from these measured values, and a method of using a value measured by the pycnometer method.

In this composite magnetic body, the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is 7 or more, the real part εr ′ of the complex permittivity is 15 or more, and (μr ′ · εr ′) ^−1/2 is 0.1 or less and (μr ′ / εr ′) ^1/2 are preferably 0.5 or more and 1 or less.
In this composite magnetic body, by setting the real part μr ′ of the complex permeability and the complex dielectric constant εr ′ within the above ranges, the electronic component or electronic device including the composite magnetic body of the present embodiment can be reduced in size. The power loss due to impedance matching can be suppressed.

Hereinafter, in this composite magnetic body, the real part μr ′ of the complex permeability, the real part εr ′ of the complex permittivity, (μr ′ · εr ′) ^−1/2 and (μr ′ / εr ′) ^{1 / The} reason why the above range is preferable as the value of ² will be described in detail, taking as an example the case where this composite magnetic body is loaded on an antenna.
The same effect can be obtained with all electronic components using high frequencies other than the antenna.

First, the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is preferably 7 or more, more preferably 9 or more. Here, the reason why μr ′ is set to 7 or more is that the real part εr ′ of the complex dielectric constant usually shows a large value of 15 or more. Therefore, when μr ′ is set to less than 7, μr ′ is smaller than εr ′. This is because the power loss due to the mismatch of the characteristic impedance is increased.
The upper limit of this μr ′ is not particularly limited, but is preferably 20 or less, more preferably 15 or less, from the aspect ratio, content, etc. of the tabular magnetic particles that can actually be produced.

The real part εr ′ of the complex dielectric constant is preferably 15 or more, more preferably 20 or more. Here, the reason why εr ′ is set to 15 or more is that it is an effective value for achieving miniaturization of the antenna according to the above equation (1).

In this composite magnetic body, it is preferable that (μr ′ · εr ′) ^−1/2 is 0.1 or less when the values of μr ′ and εr ′ are in the above ranges. The reason is as follows.
The value of (μr ′ · εr ′) ^−1/2 is the shortening rate of the high frequency wavelength in the composite magnetic material with respect to the wavelength in vacuum, as shown in the equation (1). In addition, the wavelength in vacuum and the wavelength in normal air show a substantially equal value.

In general, an antenna is usually composed of an antenna conductor made of a conducting wire having a length of 1/2 or 1/4 of a wavelength. In the long wavelength region where the frequency is low, particularly in the frequency band from 70 MHz to 500 MHz, the wavelength is 60 cm or more, and the length of the antenna conductor is 30 cm or more or 15 cm or more, and the antenna itself becomes large. Therefore, a matching circuit is used to transmit and receive signals with a long wavelength in alignment with the electronic circuit. However, when the antenna length is shortened, the amount of current on the antenna conductor is reduced, so that the antenna can transmit and receive. Problems such as a narrow frequency band and a decrease in antenna radiation efficiency occur. In particular, when the length of the antenna is set to 1/10 or less of the wavelength, transmission / reception of radio waves becomes difficult, which is a practical problem.

Therefore, if a composite magnetic body having (μr ′ · εr ′) ^−1/2 of 0.1 or less is loaded on the antenna, the high-frequency wavelength is theoretically reduced to about 1/10 or less on the composite magnetic body. Is done. For this reason, the size of the antenna can be reduced without narrowing the frequency band in which the antenna can transmit and receive or reducing the radiation efficiency of the antenna, as in the case of using a matching circuit.

The above (μr ′ / εr ′) ^1/2 is preferably 0.5 or more and 1 or less. The reason is as follows.
The value of (μr ′ / εr ′) ^1/2 is the ratio (Z _g / Z _{0 )} between the characteristic impedance Z _g of the composite magnetic material and the characteristic impedance Z _{0 of the} vacuum as shown in the above formula (2). Therefore, the characteristic impedance Z _g of the composite magnetic material is (μr ′ / εr ′) ^½ times the vacuum characteristic impedance Z ₀ . .

Usually, μr ′ of the composite magnetic body is smaller than εr ′, and therefore the characteristic impedance Z _g of the composite magnetic body is smaller than the value of the atmospheric characteristic impedance Z _A (≈vacuum characteristic impedance Z ₀ ). It is known that a high-frequency signal is attenuated by reflection or absorption when propagating from a region having a large characteristic impedance to a region having a small characteristic impedance.

Therefore, when the characteristic impedance Z _g of the composite magnetic body also reduced 50% or more than the characteristic impedance Z _A of the atmosphere, high frequency attenuation rate becomes extremely large, and practical problems. Therefore, when the value of (μr ′ / εr ′) ^1/2 is 0.5 or more, the change in characteristic impedance can be suppressed to 50% or less when electromagnetic waves propagate from the atmosphere to the composite magnetic body. Therefore, the attenuation of the high frequency signal can be suppressed. Further, the characteristic impedance Z _g of the composite magnetic body, if greater than the impedance Z _A of the atmosphere, the electromagnetic wave difference even slight these characteristic impedances is greatly attenuated. Therefore, the value of (μr ′ / εr ′) ^1/2 is preferably 1 or less.

The complex magnetic substance has a complex magnetic permeability loss tangent tan δμ of preferably 0.05 or less, and more preferably 0.04 or less. Further, the loss tangent tan δε (hereinafter sometimes simply referred to as tan δε) of the complex dielectric constant of the composite magnetic material is preferably 0.1 or less, and more preferably 0.07 or less.
As described above, when the values of tan δμ and tan δε exceed preferable values, the high frequency corresponds to the imaginary part μr ″ of the complex permeability or the imaginary part εr ″ of the complex permittivity in the composite magnetic body. Since only the portion is absorbed and changed to heat, the energy of the high-frequency signal is attenuated, and there is a possibility that problems such as a decrease in S / N ratio and heat generation may occur.

At present, in the frequency band from 70 MHz to 500 MHz, it is difficult to reduce the size of the antenna due to the long wavelength of the electromagnetic wave. Therefore, particularly downsizing such as a portable telephone, a portable information terminal, a multifunctional portable information device, etc. In applications that require this, it is necessary to extend the hop antenna to a length several times that of the casing, or substitute the earphone cord as an antenna.

On the other hand, in the composite magnetic body of this embodiment, if various characteristics such as the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz satisfy the above range, 70 MHz to 500 MHz, preferably 90 MHz to 220 MHz. Even in electronic devices and electronic devices used in frequency bands up to, for example, antennas for communication devices such as portable telephones, portable information terminals, and multifunctional portable information devices, both miniaturization and reduction of power loss are achieved. be able to.
Furthermore, in the case of a frequency band up to 500 MHz, tan δμ and tan δε are lower than in the case of a frequency band exceeding 500 MHz, which is preferable because the gain of the antenna is increased.

In the composite magnetic body of this embodiment, the flat magnetic particles are dispersed in an insulating material, thereby reducing the porosity of the obtained composite magnetic body to 20% or less, thereby reducing the μr ′ of the composite magnetic body. Although improved, εr ′ is hardly changed. As a result, the antenna of a communication device such as an electronic component or an electronic device to which the composite magnetic material is applied, for example, a portable telephone, a portable information terminal, or a multifunctional portable information device can be reduced in size, and impedance matching can be performed. The power loss due to can be suppressed.
The mechanism for obtaining such an effect is considered as follows.

When the porosity in the composite magnetic material increases, the amount of tabular magnetic particles per unit volume of the composite magnetic material decreases, so μr ′ decreases. On the other hand, since the surface of the pores has a capacitance at the interface with the tabular magnetic particles as in the case of the insulating material, the value of εr ′ hardly changes even when the porosity is increased.

Further, when the porosity in the composite magnetic body decreases, the amount of magnetic particles per unit volume of the composite magnetic body increases, so μr ′ increases. On the other hand, as described above, since the value of εr ′ is hardly affected by the porosity, the value of εr ′ is almost the same value.
That is, by decreasing the porosity in the composite magnetic material, the value of μr ′ increases, but the value of εr ′ hardly changes, so the difference between the value of μr ′ and the value of εr ′ decreases. Therefore, by setting the porosity of a composite magnetic body in which flat magnetic particles having an average aspect ratio (major axis / thickness) of 5 or more are dispersed in an insulating material to 20% or less, an electron provided with this composite magnetic body It is possible to reduce the size of components and electronic devices, and to suppress power loss due to impedance matching.

The method for reducing the porosity of the composite magnetic material is not particularly limited as long as it can reduce the porosity of the composite magnetic material to 20% or less. For example, by improving the dispersibility of the tabular magnetic particles in the insulating material, the curability of the insulating material is improved by optimizing the type and amount of the curing agent and the method for preventing aggregation of the tabular magnetic particles. A method, a method of selecting an insulating material having high fluidity, and a method in which the insulating material easily enters the gap between the tabular magnetic particles and the tabular magnetic particles. Examples thereof include a method for reducing pores, and a combination of these methods.

<Insulating material>
The insulating material only needs to be an insulating material, and the same insulating material as that described in the item of the first composite magnetic body can be used. That is, when the composite magnetic body of this embodiment is used as an antenna for a mobile phone or an antenna for a portable information terminal, it is preferable that the mechanical strength is high, the hygroscopic property is low, and the shape workability is excellent. Examples of such an insulating material include polyimide resin, polybenzoxazole resin, polyphenylene resin, polybenzocyclobutene resin, polyarylene ether resin, polysiloxane resin, epoxy resin, polyester resin, fluorine resin, polyolefin resin, polycyclohexane. Thermosetting resins or thermoplastic resins such as olefin resins, cyanate resins, polyphenylene ether resins, norbornene resins, ABS resins, and polystyrene resins are preferably used. These resins may be used alone or in combination of two or more.

Among them, a resin having a cyclic structure in the main chain and having a functional group that is polymerized in a monomer unit is unlikely to be entangled with the tabular magnetic particles, and thus there is no risk of inhibiting the orientation of the tabular magnetic particles. High μr ′ is preferable because it is easy to obtain. An example of such a resin is a dicyclopentadiene type resin.

When using a hard resin such as this dicyclopentadiene type resin, in order to reduce the porosity of the composite magnetic material, an insulating resin that imparts stretchability and flexibility may be mixed with such a hard resin. Good. The insulating resin that imparts stretchability and flexibility may be appropriately selected from the above-described resins, and liquid epoxy resins and bisphenol type epoxy resins are particularly preferable.

When this dicyclopentadiene type resin is used in combination with the above liquid epoxy resin or bisphenol type epoxy resin, the content of the dicyclopentadiene type resin with respect to the total amount of the resin is 50% by mass or more and 90% by mass or less. It is preferable. By setting the content of the dicyclopentadiene type resin in the above range, the orientation of the tabular magnetic particles can be improved and high μr ′ can be obtained.
Further, since the insulating resin imparting stretchability and flexibility is contained in an amount of 10% by mass or more and 50% by mass or less, the resin can easily enter the gap between the flat magnetic particles, and the pores of the composite magnetic material can be reduced. Since generation | occurrence | production can be suppressed and a porosity can be reduced, it is preferable.

[Method for producing second composite magnetic body]
Next, the manufacturing method of the composite magnetic body of this embodiment is demonstrated.
This method of manufacturing a composite magnetic body includes a step of mixing and dispersing the flat magnetic particles in an insulating material to produce a molding material, and a molding step of molding the obtained molding material into a predetermined shape. And a drying / curing step for drying / curing the molded body.

<Molding material production process>
In this step, the step of producing a molding material in which the flat magnetic particles are dispersed in the insulating material by mixing the flat magnetic particles, the insulating material, the solvent, and a curing agent as necessary. It is.

Since the insulating material has already been described, the description thereof will be omitted.
When a thermosetting resin is used as the insulating material, the type and amount of the curing agent may be appropriately adjusted according to the type and amount of the thermosetting resin to be used.
In the case of using an epoxy resin as the thermosetting resin, a tertiary amine is preferable in that the condensation reaction between the epoxy groups is promoted to prevent generation of pores due to poor curing in the molded body of the composite magnetic body.

Examples of the tertiary amine include 1-isobutyl-2-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and the like. It is done.
In consideration of the point of promoting the condensation reaction of the functional group, the addition amount of the curing agent is 0.5% by mass or more and 3% by mass or less based on the total mass of the thermosetting resin and the curing agent. That's fine.

The solvent is not particularly limited as long as it can dissolve the above-described insulating material. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetyl acetone, cyclohexanone, benzene, toluene, xylene, Aromatic hydrocarbons such as ethylbenzene, diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl Ethers such as ether, dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, etc. Amides are preferably used.
These solvents may be used alone or in combination of two or more. In particular, a solvent having a high boiling point such as cyclohexanone or xylene is preferable because it can suppress the thickening of the molding material due to the volatilization of the solvent.

The solvent is preferably mixed in an amount of 30% by mass or more in the molding material, and more preferably 35% by mass or more.
By mixing 30% by mass or more of the solvent, the viscosity of the obtained molding material is reduced. Therefore, even when the flat magnetic particles are aggregated during mixing, the aggregation is loosened and the dispersibility in the insulating material is reduced. Will improve. Thereby, the porosity of a composite magnetic body can be reduced.
In addition, when there is too much quantity of a solvent, since the drying mentioned later takes time and there exists a possibility that a pore may produce | generate at the time of drying, it is preferable that the quantity of a solvent is 50 mass% or less.

The content of the tabular magnetic particles in the molding material is preferably 10% by volume or more and 60% by volume or less, more preferably 30% by volume with respect to the total amount of the insulating material, the curing agent, and the tabular magnetic particles. % To 50% by volume.
Here, if the content of the tabular magnetic particles is less than 10% by volume, the amount of the tabular magnetic particles is too small, and the magnetic properties as a composite magnetic body are deteriorated. On the other hand, when the content of the tabular magnetic particles exceeds 60% by volume, there are too many tabular magnetic particles, and a molding material containing the tabular magnetic particles, an insulating material, a curing agent, and a solvent is included. Since fluidity | liquidity falls and therefore the moldability at the time of shape | molding using this molding material will fall, it is unpreferable.

These flat magnetic particles, an insulating material, a solvent, and a curing agent as necessary are mixed to obtain a molding material.
The mixing device is not particularly limited as long as the flat magnetic particles, the insulating material, the curing agent, and the solvent can be uniformly mixed and dispersed to form a slurry-like molding material. A revolving mixer, a homogenizer, an ultrasonic homogenizer, a stirrer and the like can be mentioned. When mixing with these apparatuses, the mixing conditions may be appropriately adjusted so that the tabular magnetic particles do not aggregate too much and are uniformly dispersed in the insulating material.

<Molding process>
This is a step of molding the molding material obtained in the above-described step into a sheet, film or bulk having a predetermined shape.
The molding method is not particularly limited as long as the molding material can be molded into a certain shape and the shape after molding can be maintained.
Further, the shape and size of the molded body are not particularly limited, and for example, it may be molded into a sheet shape or a film shape, or may be molded into a shape having a thickness such as a rectangular parallelepiped shape, for example, a bulk shape.

When forming into a sheet form or a film form, it can obtain easily by apply | coating said molding material on a sheet-like or film-form base | substrate. This method is preferable because it is excellent in mass productivity.
Examples of the method for forming the sheet or film include a doctor blade method, a bar coating method, a die coating method, and a pressing method. Moreover, when shape | molding in the shape with thickness, such as a thin plate shape, the method etc. which pour molding material into the type | molds of arbitrary shapes are mentioned, for example.
Moreover, when laminating | stacking a composite magnetic body and it is set as a laminated structure, it is preferable to laminate | stack the composite magnetic body shape | molded by the doctor blade method in the sheet form or the film form.

<Orientation process>
This is a step of orienting flat magnetic particles having an average aspect ratio (major axis / thickness) of 5 or more in the molded body obtained in the molding step in one direction.
When the molded body obtained in the above molding step has a desired μr ′, this orientation step is unnecessary, but in order to obtain a composite magnetic body having a higher μr ′, it can be obtained. It is preferable to apply an orientation process in which a magnetic field is applied to the compact and the tabular magnetic particles in the compact are oriented in one direction.

The method for orienting the tabular magnetic particles in the molded body is not particularly limited as long as a magnetic field is applied so that the tabular magnetic particles in the molded body can be oriented in one direction.
When a magnetic field is applied to the flat magnetic particles in the compact, if the magnetic field lines are bent in the compact, the flat magnetic particles cannot be oriented in one direction. Therefore, it is preferable to apply the magnetic field so that the generated magnetic field lines are substantially parallel to the surface of the molded body.

The magnitude of the applied magnetic field is preferably 100 gauss or more and 3000 gauss or less. If the magnitude of the magnetic field is less than 100 gauss, the magnetic field is too small, and the flat magnetic particles in the compact may not be sufficiently oriented in one direction. On the other hand, if it exceeds 3000 gauss, the magnetic field becomes too large, and the magnetic field may cause the tabular magnetic particles to aggregate and separate from the insulating material, which is inadequate for the magnetic properties of the obtained composite magnetic material. This is not preferred because there is a risk of uniformity.

<Drying / curing process>
This is a step of drying and curing the molded body in which the tabular magnetic particles are oriented in the orientation step to obtain a composite magnetic material.
Here, the molded body in which the flat magnetic particles are oriented is dried, and then the insulating material is cured by heating or ultraviolet irradiation.
The drying / curing conditions (processing temperature, processing time, etc.) may be appropriately adjusted according to the type of insulating material and solvent used.

"Pressing process"
If the porosity of the molded body obtained in the drying step is 20% or less, this pressing step is unnecessary. However, when the porosity of the molded body exceeds 20%, the porosity of the molded body is further increased. When it is desired to decrease, it is preferable to perform a step of pressing the formed body after the drying step. A known press apparatus may be used as appropriate.

When a resin is used as the insulating material when applying pressure to the molded body with a press apparatus, it is preferable to apply pressure at a temperature higher than the softening temperature of the resin and lower than the curing start temperature in order to effectively reduce pores.
The pressure during pressing may be adjusted as appropriate, but it is preferable to apply a pressure of about 5 MPa to 20 MPa.
As described above, the composite magnetic body of the present embodiment can be obtained.

[Third composite magnetic body]
The composite magnetic body of the present embodiment is a composite magnetic body including the first composite magnetic body including a first resin in which the insulating material has a cyclic structure in a main chain and has a functional group that is polymerized in a monomer unit. is there.

<First resin>
The first resin is a resin having a cyclic structure in the main chain and a functional group that is polymerized in monomer units. The resin is not particularly limited as long as it is a resin capable of obtaining a molding material having low viscosity and fluidity when mixed with flat magnetic particles, and is not particularly limited, but is a thermosetting resin, a thermoplastic resin, or an ultraviolet curable resin. Can be used.

Such resins include epoxy resins, silicone resins, phenol resins, polyimide resins, polybenzoxazole resins, polyphenylene resins, polybenzocyclobutene resins, polyarylene ether resins, polycyclohexane resins, polyester resins, fluororesins, polyolefin resins. Polycycloolefin resin, cyanate resin, polyphenylene ether resin, polystyrene resin, acrylic resin, methacrylic resin, urethane resin, urethane-acrylic resin, epoxy-acrylic resin and the like. These resins may be used alone or in combination of two or more.
Among these, a thermosetting resin is preferable because it has solubility in many solvents and the viscosity can be easily adjusted, and among the thermosetting resins, an epoxy resin and a polycycloolefin resin are preferable.

Here, as an example of an epoxy resin as a resin having a cyclic structure in the main chain, a dicyclopentadiene type epoxy resin (formula (1)) having only a cyclic structure in the main chain or a naphthalene type epoxy resin (formula ( 2)) is preferably used.

In formula (2), R ₁ is hydrogen or a methyl group.

As the resin having a linear structure in the main chain, a resin having a short linear structure of C = 1 to 3 in the linear chain of the cresol novolac type epoxy resin (formula (3)) can be mentioned. In the formula (3), X is a linear structure having a short alkyl chain of C = 1 to 3, and a linear structure of C = 1 is preferable.

In the formula (3), X is an alkyl chain of C = 1 to 3, R ₂ is hydrogen, an alkyl group having a molecular weight in the range of 15 to 180, or an aryl group.
Examples of X include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, phenyl group, benzyl group and tolyl group.

In addition, as a resin having a linear structure in the main chain, a resin (formula (4)) having a short linear structure of C = 1 to 3 in the linear chain of a dicyclopentadiene type epoxy resin may be used. Can do.
In the formula (4), X is a linear structure having an alkyl chain of C = 1-3.
Examples of X include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a phenyl group, a benzyl group, and a tolyl group as in the formula (3).

Even if the resin having the structure described above is a resin that is difficult to be entangled with the flat magnetic particles, the real part μr ′ of the complex magnetic permeability of the composite magnetic material may be reduced as the polymer chain becomes longer. Therefore, n in the above formulas (1), (3), and (4) is preferably 0 to 3, and more preferably n = 0.
That is, it is preferable to use a monomer alone or use a combination of a monomer and an oligomer as appropriate.

The content of the tabular magnetic particles in the total amount of the composite magnetic material is preferably 10% by mass to 60% by mass, and more preferably 30% by mass to 50% by mass.
Here, when the content of the tabular magnetic particles is less than 10% by mass, the ratio of the tabular magnetic particles is too small, and the μr ′ of the obtained composite magnetic body becomes too low, and as a result. This is not preferable because a desired μr ′ cannot be secured.
On the other hand, when the content of the tabular magnetic particles exceeds 60% by mass, the amount of the tabular magnetic particles is too large, so the amount of the resin is relatively small, and the tabular magnetic particles and the resin Is not preferable because a molding material having low viscosity and fluidity cannot be obtained, and the orientation of the tabular magnetic particles in the subsequent process becomes insufficient.

The angle formed by the orientation direction of the tabular magnetic particles in the composite magnetic body and the major axis direction of the tabular magnetic particles is preferably 20 ° or less, more preferably 0 ° or more and 15 ° or less, and still more preferably. It is 0 degree or more and 10 degrees or less.
When the major axis direction of the tabular magnetic particles is inclined within the above range with respect to the orientation direction of the tabular magnetic particles, a composite magnetic body having a high μr ′ can be obtained.
Here, the “orientation direction” is the direction in which the long axes of the tabular magnetic particles are oriented, that is, the long axis direction of a plurality of tabular magnetic particles when the cross section of the composite magnetic body is observed. The direction in which the standard deviation of the angle is the smallest.

In the frequency band from 70 MHz to 500 MHz, μr ′ of this composite magnetic body is preferably 7 or more, and more preferably 10 or more.
Here, the reason why μr ′ is set to 7 or more is that as μr ′ increases, the wavelength shortening rate increases, and therefore, electronic components and circuit boards to which this composite magnetic material is applied can be further miniaturized. is there.

[Method for Producing Third Composite Magnetic Material]
In the second step of the first composite magnetic body manufacturing method, the third composite magnetic body manufacturing method includes a first functional group that has a cyclic structure in the main chain and polymerizes in monomer units as an insulating material. This is exactly the same as the manufacturing method of the first composite magnetic body except that the molding material is included.
Here, in order to obtain a composite magnetic body having a higher μr ′, in the third step of the first composite magnetic body manufacturing method, a magnetic field is applied to the obtained compact after the molding step, It is preferable to perform an orientation process for orienting the flat magnetic particles in the molded body in one direction, and then perform the drying and curing processes.

Next, the manufacturing method of the third composite magnetic body will be described in detail.
<Molding material production process>
First, a molding material is prepared by mixing a resin having a cyclic structure in the main chain and having a functional group that is polymerized in monomer units, tabular magnetic particles, a solvent, and a curing agent as necessary.

The resin having a cyclic structure in the main chain and a functional group that is polymerized in monomer units may be any resin as long as it can obtain a molding material having low viscosity and fluidity when mixed with flat magnetic particles. Although not particularly limited, a thermosetting resin, a thermoplastic resin, or an ultraviolet curable resin can be used.

Such resins include epoxy resins, silicone resins, phenol resins, polyimide resins, polybenzoxazole resins, polyphenylene resins, polybenzocyclobutene resins, polyarylene ether resins, polycyclohexane resins, polyester resins, fluororesins, polyolefin resins. Polycycloolefin resin, cyanate resin, polyphenylene ether resin, polystyrene resin, acrylic resin, methacrylic resin, urethane resin, urethane-acrylic resin, epoxy-acrylic resin and the like. These resins may be used alone or in combination of two or more.
Among these, a thermosetting resin is preferable because it has solubility in many solvents and the viscosity can be easily adjusted, and among the thermosetting resins, an epoxy resin and a polycycloolefin resin are preferable.

For example, as an epoxy resin having a cyclic structure in the main chain, a dicyclopentadiene type epoxy resin having only a cyclic structure in the main chain represented by the above formula (1), and a naphthalene type epoxy represented by the formula (2) Resin.
In addition, as the epoxy resin having a linear structure in the main chain, a cresol novolac type epoxy resin having a short straight chain of C = 1 to 3 represented by the above formula (3), represented by the formula (4) Examples thereof include dicyclopentadiene type epoxy resins having a short straight chain of C = 1 to 3.

Even if the resin having the above structure is a resin that is not easily entangled with the flat magnetic particles, if the polymer chain becomes long, the μr ′ of the composite magnetic material may be reduced. Therefore, n in the above formulas (1), (3), and (4) is preferably 0 to 3, and more preferably n = 0.
That is, it is preferable to use a monomer alone or use a combination of a monomer and an oligomer as appropriate.

What is necessary is just to adjust suitably the kind and addition amount of a hardening | curing agent according to resin to be used.
When an epoxy resin is used as the above resin, a tertiary amine is preferable in that the condensation reaction between epoxy groups is promoted to improve the mechanical strength of the composite magnetic body.
Examples of the tertiary amine include 1-isobutyl-2-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and the like. It is done.
In consideration of the point of promoting the condensation reaction of the functional group, the addition amount of the curing agent may be 0.5 mass% or more and 3 mass% or less with respect to the total mass of the resin and the curing agent.

In addition, a curing agent having a cyclic structure is preferable in the same manner as the above-described resin in that the influence of steric hindrance on the tabular magnetic particles is reduced and the μr ′ of the composite magnetic material is improved.
Examples of the curing agent having a cyclic structure include a phenol novolac type curing agent, a zylock type curing agent, a dicyclopentadiene type curing agent, and the like. These curing agents are preferably added in the same amount as the resin because the driving force for polymerizing the resin is weak compared to tertiary amines and the like.

The solvent is not particularly limited as long as it can dissolve the above-mentioned resin. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetyl acetone, cyclohexanone, benzene, toluene, xylene, ethyl benzene, etc. Aromatic hydrocarbons, diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, etc. Ethers such as dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone and the like S is preferably used.
These solvents may be used alone or in combination of two or more. In particular, a solvent having a high boiling point such as cyclohexanone or xylene is preferable because it can suppress the thickening of the molding material due to the volatilization of the solvent.

The content of the tabular magnetic particles in the molding material is based on the volume (resin + curing agent + tabular magnetic particles) when the volatile components in the molding material are cured and become solid. 10 volume% or more and 60 volume% or less are preferable, More preferably, they are 30 volume% or more and 50 volume% or less.
Here, if the content of the tabular magnetic particles is less than 10% by volume, the tabular magnetic particles are too small and the magnetic properties as the composite magnetic material are deteriorated. On the other hand, the tabular magnetic particles are contained. If the rate exceeds 60% by volume, there are too many tabular magnetic particles, the fluidity of the molding material containing the tabular magnetic particles, the resin, the curing agent, and the solvent decreases, and the moldability decreases. This is not preferable.

These flat magnetic particles, resin, curing agent and solvent are mixed to obtain a molding material. In this case, the viscosity of the molding material can be adjusted by appropriately adjusting the amount of the solvent added.
The mixing device is not particularly limited as long as the flat magnetic particles, the resin, the curing agent, and the solvent can be mixed uniformly to form a slurry-like molding material. For example, a roll mill, a self-revolving mixer, Examples thereof include a homogenizer, an ultrasonic homogenizer, and a stirrer.

The viscosity of the molding material is preferably 0.1 Pa · S or more and 10 ⁶ Pa · S or less, more preferably 0.3 Pa · S or more and 10 ⁴ Pa · S or less.
Here, when the viscosity is less than 0.1 Pa · S, the fluidity becomes too high and the productivity in the drying process is deteriorated. On the other hand, when the viscosity exceeds 10 ⁶ Pa · S, the viscosity is too high. Therefore, the orientation of the tabular magnetic particles is difficult to occur, and as a result, the orientation of the tabular magnetic particles in the composite magnetic material is lowered, which is not preferable.
Thus, by setting the content of the tabular magnetic particles to 10 volume% or more and 60 volume% or less, and setting the viscosity of the molding material to 0.1 Pa · S or more and 10 ⁶ Pa · S or less, μr ′ and A composite magnetic body in which the mechanical strength of the molded body is balanced can be obtained.

<Molding>
The molding method is not particularly limited as long as a certain shape can be maintained during the step of applying a magnetic field to the molding material.
Further, the shape and size of the molded body are not particularly limited, and for example, it may be molded into a sheet shape or a film shape, or may be molded into a shape having a thickness such as a rectangular parallelepiped shape.
A sheet or film molded is preferable because it can be easily obtained by applying the molding material to a sheet or film substrate and is excellent in mass productivity.

In the case of molding into a sheet or film, for example, when the viscosity of the molding material is 10 Pa · S or less, a doctor blade method, a bar coating method or the like can be used, and the viscosity of the molding material is 10 Pa · s. In the case of exceeding, die coating method or the like can be used. Moreover, when shape | molding to a shape with thickness, the method of pouring a molding material into the type | mold of arbitrary shapes, etc. are mentioned, for example.

When the molding material is simply molded into a sheet shape, a film shape, a rectangular parallelepiped shape, or the like, the tabular magnetic particles may be oriented in random directions and the orientation may not be sufficient.
Therefore, a magnetic field is applied to the molded body formed into a sheet shape, a film shape, a rectangular parallelepiped shape, or the like, and the flat magnetic particles in the molded body are oriented.

<Orientation>
The method for orienting the tabular magnetic particles in the compact is not particularly limited as long as a magnetic field is applied so that the tabular magnetic particles in the compact can be oriented in one direction. If the magnetic field lines are bent, the tabular magnetic particles cannot be oriented in one direction. Therefore, it is necessary to apply the magnetic field so that the generated magnetic field lines are substantially parallel to the surface of the molded body.
As such an alignment method, there are the following four alignment methods.

(1) Orientation method A
FIG. 3 is a schematic configuration diagram showing an orientation apparatus for carrying out the orientation method A in the method for producing a composite magnetic body of the present invention. The molding material (not shown) is applied to the base 1 in the form of a sheet or film This is an example of an apparatus for orienting flat magnetic particles in the coating film 2 by magnetic lines of force H generated by applying a magnetic field to the coating film 2 coated on the upper surface.

The aligning device 11 includes a coating means 12 including a dispenser that forms the coating film 2 by coating the molding material (not shown) on the upper surface of the substrate 1 that proceeds in the direction of the arrow in the drawing, and the coating film 2. A pair of magnets 13a and 13b that are respectively provided on both sides in the width direction and orient the flat magnetic particles in the coating film 2 by magnetic lines H generated by applying a magnetic field to the coating film 2 along the width direction; , And drying means 14 for drying the coating film 2 in which the flat magnetic particles are oriented by the magnetic lines of force H. The magnets 13a and 13b are arranged so that the opposing poles are different from each other.

In this orientation device 11, since a magnetic field is generated from the N pole of the magnet 13a toward the S pole of the magnet 13b, the coating film 2 passing between the magnets 13a and 13b is applied to the S of the magnet 13b from the N pole of the magnet 13a. Magnetic field lines H parallel to the direction toward the pole are generated. Due to the magnetic force lines H, the tabular magnetic particles in the coating film 2 are oriented parallel to the magnetic force lines H.
As described above, the tabular magnetic particles in the coating film 2 can be oriented parallel to the magnetic field lines H.

(2) Orientation method B
FIG. 4 is a schematic configuration diagram showing an orientation device for carrying out the orientation method B in the method for producing a composite magnetic body of the present invention. The orientation device 21 is different from the orientation device 11 in FIG. This is in that the opposing poles of a pair of magnets 22a and 22b provided on the upper side and the lower side of the film 2 are arranged so as to have the same polarity.

In this orientation device 21, when a magnetic field is applied to the coating film 2 by a pair of magnets 22 a and 22 b, the magnetic lines of force generated from one magnet 22 a and the magnetic lines of force generated from the other magnet 22 b repel each other at the position of the coating film 2. Therefore, the lines of magnetic force H1 and H2 for applying a magnetic field parallel to the surface of the coating film 2 are generated. Due to the magnetic lines of force H1 and H2, the tabular magnetic particles in the coating film 2 are oriented in parallel to the magnetic lines of force H1 and H2.
As described above, the plate-like magnetic particles in the coating film 2 can be oriented in parallel to the magnetic lines of force H1 and H2.

(3) Orientation method C
FIG. 5 is a schematic configuration diagram showing an orientation device for carrying out the orientation method C in the method for producing a composite magnetic body of the present invention. The orientation device 31 is different from the orientation device 21 in FIG. A fixed interval, for example, so that the opposing poles of each of the pair of magnets 32a and 32b, the magnets 33a and 33b, and the magnets 34a and 34b provided on the upper side and the lower side of the film 2 are the same, respectively. It is the point arrange | positioned at the space | interval which the magnetic force lines of adjacent magnets do not cancel each other.

For example, in the orientation device 21 shown in FIG. 4, since the magnetic lines H1 and H2 generated from the N poles of the magnets 22a and 22b return to the S pole, the magnetic lines of force are applied near the both ends in the horizontal direction of the magnets 22a and 22b. Magnetic field lines that are perpendicular to the surface 2 and not parallel to the coating film 2 are also generated, and as a result, the orientation of the tabular magnetic particles may be lowered.

On the other hand, in the orientation device 31 shown in FIG. 5, as shown in FIG. 6, before the coating film 2 passes between the pair of magnets 32a and 32b, the plate-like magnetic particles 41 in the coating film 2 have an orientation direction. Although it is in a disordered state, the tabular magnetic particles 41 in the coating film 2 are caused by the lines of magnetic force H1 and H2 generated parallel to the surface of the coating film 2 by passing between the magnets 32a and 32b. The tabular magnetic particles 41 are aligned along the magnetic field lines H1 and H2.

However, the orientation of the tabular magnetic particles 41 may be insufficient only by passing between the first magnets 32a and 32b. Therefore, by passing between the magnets 33a and 33b, the insufficient orientation of the tabular magnetic particles 41 is corrected and the orientation is improved. After passing between the last magnets 34a and 34b, the insufficient orientation of the tabular magnetic particles 41 is corrected and becomes highly oriented.
Thus, the orientation of the tabular magnetic particles 41 in the coating film 2 can be improved by applying the magnetic field to the coating film 2 a plurality of times.

(4) Orientation method D
FIG. 7 is a schematic configuration diagram showing an orientation device for performing the orientation method D in the method for producing a composite magnetic body of the present invention. The orientation device 51 is different from the orientation device 21 in FIG. A drying means 52 for pre-drying the coating film 2 is provided at a position where H1 and H2 are parallel to the tabular magnetic particles 41 in the coating film 2.

The drying means 52 is not particularly limited as long as it has a drying function capable of solidifying the coating film 2, and examples thereof include a hot air blowing nozzle connected to a hot air supply source.

In the orientation device 51, when a magnetic field is applied to the coating film 2 by the pair of magnets 22a and 22b, magnetic lines H1 and H2 for applying a magnetic field parallel to the surface of the coating film 2 are generated, and the magnetic lines H1 and H2 are generated. Thus, the tabular magnetic particles in the coating film 2 are oriented parallel to the magnetic field lines H1 and H2. At this time, if the coating film 2 is pre-dried by the drying means 52, the coating film 2 is solidified, so that the orientation state of the flat magnetic particles that are oriented in parallel to the magnetic lines of force H 1 and H 2 can be fixed.
As described above, the plate-like magnetic particles in the coating film 2 can be oriented parallel to the magnetic field lines H1 and H2.

As described above, the orientation of the tabular magnetic particles in the coating film 2 can be improved by performing only one of the orientation methods A to D alone or in combination of two or more. it can.
Even when the coating film 2 is replaced with a molded body having a predetermined shape, the orientation of the tabular magnetic particles in the molded body can be improved by appropriately applying one or more of the orientation methods A to D. it can.

The magnets 13a, 13b,... Include electromagnets and permanent magnets. The arrangement of the magnets and the number of pairs are not particularly limited, and may be appropriately adjusted according to the shape of the coating film and the molded body and the required magnetic characteristics.

The magnitude of the magnetic field to be applied is preferably 100 gauss or more and 1000 gauss or less when different polarities such as those of the alignment apparatus shown in FIG. If the magnitude of the magnetic field is less than 100 gauss, the magnetic field is too small, and the flat magnetic particles in the compact may not be sufficiently oriented. On the other hand, if it exceeds 1000 gauss, the magnetic field is too large and the flat magnetic particles and the resin may be separated, resulting in non-uniformity in the magnetic properties of the obtained composite magnetic material.
Further, when the same poles as in the orientation device shown in FIG. 4 are faced to each other, separation between the tabular magnetic particles and the resin is difficult to occur, and therefore it is preferably 100 gauss or more and 3000 gauss or less.

<Drying and curing>
The molded body in which the flat magnetic particles are oriented is dried, and then the resin is cured by heating or ultraviolet irradiation. The drying / curing conditions (processing temperature, processing time, etc.) may be appropriately adjusted according to the type of resin and solvent used.
Thus, the third composite magnetic body can be obtained.

[Fourth composite magnetic body]
The composite magnetic body of the present embodiment includes a first resin in the first composite magnetic body, wherein the insulating material has a cyclic structure in the main chain and has a functional group that is polymerized in a monomer unit. The composite magnetic body further includes a second resin that imparts flexibility to one resin.

The real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz of this composite magnetic body is preferably 7 or more, more preferably 10 or more.
Here, the reason why the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz of this composite magnetic material is set to 7 or more is that the larger the μr ′, the greater the wavelength shortening rate. This is because further downsizing of electronic parts and circuit boards to which the body is applied becomes possible.

The loss tangent tan δμ of the complex magnetic permeability of this composite magnetic body is preferably 0.05 or less, more preferably 0.04 or less. Here, when tan δμ exceeds 0.05, only the portion corresponding to the imaginary part μr ″ of the complex magnetic permeability is absorbed in the composite magnetic body and changed to heat, whereby the energy of the high frequency signal is changed. In addition to attenuation, problems such as a decrease in S / N ratio and heat generation may occur, which may reduce the gain.

Here, the 2nd resin which comprises the composite magnetic body of this embodiment is demonstrated in detail.
The second resin is a resin that imparts flexibility to the first resin having a cyclic structure in the main chain and having a functional group that is polymerized in a monomer unit.
The second resin may be a resin that can impart flexibility and stretchability to the resulting cured body when mixed and molded and cured with the first resin and flat magnetic particles. There is no particular limitation, and for example, a resin having excellent flexibility such as an epoxy resin, a silicone resin, a urethane resin, or a polyamide resin is suitable.
Alternatively, a modified epoxy resin modified with urethane, polyethylene, ethylene propylene, or the like as the epoxy resin, or a propylene oxide-added epoxy resin obtained by adding propylene oxide to the epoxy resin can be used.

As such a resin imparting flexibility, an epoxy resin is preferable, and for example, an epoxy resin having a bisphenol skeleton such as bisphenol A type, bisphenol B type, and bisphenol F type is more preferable.
Examples of the epoxy resin having a bisphenol A type skeleton include isopropylidene bisphenol, isopropylidene bis (orthocresol), tetrabromobisphenol A, 1,3-bis (4-hydroxycumylbenzene), 1,4-bis (4 -Hydroxycumylbenzene) and the like.

Examples of the epoxy resin having a bisphenol B type skeleton include 2,2-bis (4-hydroxyphenyl) butane.
Examples of the epoxy resin having a bisphenol F-type skeleton include methylene bisphenol and methylene bis (orthocresol).

Among the epoxy resins having a bisphenol skeleton, an epoxy resin having at least one of a bisphenol A skeleton and a bisphenol F skeleton is preferable. Among these, an epoxy resin having a bisphenol A skeleton is preferable from the viewpoints of stretchability and shear strength.

Of the epoxy resins having a bisphenol skeleton, an epoxy resin having two or more epoxy groups in one molecule and having an ether skeleton is preferable. Examples of the structure containing two or more epoxy groups in one molecule include diglycidyl ether, diglycidyl ester, diglycidyl amine and the like.

The ether skeleton is not particularly limited as long as it is a compound containing one or more ether partial structures. Examples of such an ether skeleton include alkylene glycol.
The alkylene glycol preferably has 2 to 6 carbon atoms of alkylene, more preferably 2 to 5, and still more preferably 2 to 4.
The ether skeleton may be linear or may have a branched chain, but an ether skeleton derived from ethylene glycol or propylene glycol is preferable.

Further, as a structure having a bisphenol A type skeleton, containing two or more epoxy groups in one molecule, and having an ether skeleton, for example, an ether skeleton made of propylene glycol is added to a bisphenol A type skeleton. A propylene glycol-added bisphenol A type structure (chemical formula (5)) in which glycidyl ether is introduced at the terminal of the bisphenol A type skeleton.

In this chemical formula (5), the value of p + q is 1 to 5, but a more preferable value of p + q is 2 to 4, and a more preferable value is 2 to 3.

As another example of this structure, an ether skeleton made of ethylene glycol is introduced into a bisphenol A skeleton instead of an ether skeleton made of propylene glycol, and glycidyl ether is introduced at the end of the bisphenol A skeleton. Moreover, the ethylene glycol addition bisphenol A type structure represented by Chemical formula (6) is also mentioned.

In this chemical formula (6), the value of n + m is 1 to 10, but a more preferable value of n + m is 4 to 8, and a more preferable value is 6.

Resins having a bisphenol A skeleton and containing two or more epoxy groups in one molecule and having a polyether skeleton include bisphenol A bis (propylene glycol glycidyl ether) ether and bisphenol A bis (triethylene glycol). Glycidyl ether) ether and the like.

When the first resin and the second resin are used in combination, it is preferable to use a dicyclopentadiene type epoxy resin of n = 0 in the chemical formula (1) as the first resin. Is preferably used in combination with a resin that imparts flexibility of chemical formula (5) or chemical formula (6).

As a mixing ratio of the first resin and the second resin, the second resin is contained in an amount of 5% by mass to 30% by mass with respect to the total mass of the first resin and the second resin. Is preferred.
By mixing the second resin with the first resin within the above range, when the composite magnetic body is molded and manufactured on the base material, the composite magnetic body has excellent peelability from the base material. Since elasticity and flexibility can be imparted to the extent, it is preferable.

[Fourth Method for Manufacturing Composite Magnetic Material]
Next, the manufacturing method of the 4th composite magnetic body is demonstrated.
In the second method of manufacturing the third composite magnetic body, the fourth composite magnetic body manufacturing method includes a first functional group that has a cyclic structure in the main chain and polymerizes in monomer units as an insulating material in the second step of the third composite magnetic body manufacturing method. This is exactly the same as the manufacturing method of the third composite magnetic body except that the molding material further includes a second resin that is a resin that imparts flexibility to the first resin.

<Molding material production process>
In this step, a first resin having a cyclic structure in the main chain and having a functional group that is polymerized in a monomer unit, a second resin that imparts flexibility to the first resin, and a plate-like magnetic property This is a step of preparing a molding material by mixing body particles, a solvent, and, if necessary, a curing agent.
Since the composition, shape, characteristics, manufacturing method, and the like of each of the first resin, the second resin, and the tabular magnetic particles have already been described, description thereof will be omitted.

In addition, 1st resin and 2nd resin may be synthesize | combined by a well-known method, and a commercial item may be used.
In addition, as a commercially available product of the second resin, a trade name “ADEKA RESIN EP-4000” (manufactured by ADEKA Corporation (p + q = 2 in the above chemical formula (5))), a trade name “RIKARESIN BPO-20E” (new) Made by Nippon Rika Co., Ltd. (the above chemical formula (5) with p + q = 2), trade name “Rikaresin BEO-60E” (manufactured by Shin Nippon Rika Co., Ltd. (with above chemical formula (6), n + m = 6)) preferable.

What is necessary is just to adjust suitably about the kind and addition amount of a hardening | curing agent in the case of using said 1st resin and 2nd resin according to the kind and amount of resin to be used.
When an epoxy resin is used as the above resin, a tertiary amine is preferable in that the condensation reaction between epoxy groups is promoted to improve the mechanical strength of the composite magnetic body.

Examples of the tertiary amine include 1-isobutyl-2-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and the like. It is done.
In consideration of the point of promoting the condensation reaction of the functional group, the addition amount of the curing agent may be 0.5% by mass to 3% by mass with respect to the total mass of the resin and the curing agent.

Moreover, as said hardening | curing agent, the hardening agent which has a cyclic structure in a principal chain similarly to said resin in the point that the influence of the steric hindrance with respect to a flat magnetic particle is made small and micror 'of a composite magnetic body is improved Is preferred.
Examples of the curing agent having a cyclic structure include a phenol novolac type curing agent, a zylock type curing agent, a dicyclopentadiene type curing agent, and the like. These hardeners are preferably added in the same amount as the resin because the driving force for polymerizing the resin is weaker than tertiary amines.

Examples of the solvent are the same as those mentioned in the third composite magnetic body.

The content rate of the flat magnetic particles in the molding material is determined by the volume V1 of the first resin and the volume V2 of the second resin when the components other than the volatile components in the molding material are cured and become solid. It is preferably 10% by volume to 60% by volume, more preferably 30% by volume to 50% by volume, based on the sum of the volume V3 of the agent and the volume V4 of the tabular magnetic particles (V1 + V2 + V3 + V4).
Here, if the content of the tabular magnetic particles is less than 10% by volume, the tabular magnetic particles are too small and the magnetic properties as a composite magnetic body are deteriorated. When the content of the particles exceeds 60% by volume, there are too many tabular magnetic particles, and the fluidity of the molding material containing the tabular magnetic particles, the resin, the curing agent, and the solvent is reduced. When a molded body is formed from this molding material, the orientation of the tabular magnetic particles is difficult to occur, and as a result, the orientation of the tabular magnetic particles in the composite magnetic body is lowered, which is not preferable.

These flat magnetic particles, first resin, second resin, curing agent and solvent are mixed to produce a molding material. In this case, the viscosity of the molding material can be adjusted by appropriately adjusting the amount of the solvent added.
Examples of the mixing apparatus include the same ones as those mentioned in the first composite magnetic body.

The viscosity of the obtained molding material is preferably 0.1 Pa · S or more and 10 ⁶ Pa · S or less, more preferably 0.3 Pa · S or more and 10 ⁴ Pa · S or less.
Here, when the viscosity is less than 0.1 Pa · S, it is not preferable because the fluidity becomes too high and the productivity in the drying process is deteriorated. On the other hand, when the viscosity exceeds 10 ⁶ Pa · S, the viscosity is Is too high, and the orientation of the tabular magnetic particles is difficult to occur. As a result, the orientation of the tabular magnetic particles in the composite magnetic material is lowered, which is not preferable.

Thus, the content of the tabular magnetic particles in the molding material is 10 volume% or more and 60 volume% or less, and the viscosity of the molding material is 0.1 Pa · S or more and 10 ⁶ Pa · S or less. By doing so, a composite magnetic body in which μr ′ and the mechanical strength of the compact are balanced can be obtained.

<Molding process>
This is a step of molding the molding material obtained in the above step into a predetermined shape.
The molding method is not particularly limited as long as the molding material can be molded into a constant shape and can maintain a constant shape when a magnetic field is applied after molding.
Further, the shape and size of the molded body are not particularly limited, and for example, it may be molded into a sheet shape or a film shape, or may be molded into a shape having a thickness such as a rectangular parallelepiped shape, for example, a bulk shape.

In the case of molding into a sheet or film, it can be easily obtained by applying the molding material on a sheet or film substrate. This method is preferable because it is excellent in mass productivity.

When molding into a sheet or film, for example, when the viscosity of the molding material is 10 Pa · S or less, a doctor blade method, a bar coating method, or the like can be used. Moreover, when the viscosity of the molding material exceeds 10 Pa · S, a die coating method or the like can be used. Moreover, when shape | molding to a shape with thickness, the method of pouring a molding material into the type | mold of arbitrary shapes, etc. are mentioned, for example.

When the molding material is simply molded into a sheet shape, a film shape, a rectangular parallelepiped shape, or the like, the tabular magnetic particles may be oriented in random directions and the orientation may not be sufficient.
Therefore, a magnetic field is applied to the molded body formed into a sheet shape, a film shape, a rectangular parallelepiped shape or the like, and the flat magnetic particles in the molded body are oriented in one direction.

<Orientation process>
The alignment step of the fourth composite magnetic body is the same as the alignment step described in the third composite magnetic body.

<Drying / curing process>
This is a step of drying and curing the molded body in which the tabular magnetic particles are oriented in the orientation step to obtain a composite magnetic material.
This drying / curing process is the same as the drying / curing process of the third composite magnetic body.

<Pressing process>
When it is desired to further reduce the porosity of the molded body obtained in the drying step, it is preferable to perform a step of pressing the molded body after the drying step. A known press apparatus may be used as appropriate.

When pressure is applied to the molded body with a press device, in order to effectively reduce pores, it is preferable to apply pressure above the softening temperature of the resin and below the curing start temperature.
The pressure during pressing may be adjusted as appropriate, but it is preferable to apply a pressure of about 5 MPa to 20 MPa.
As described above, the composite magnetic body of the present embodiment can be obtained.

[antenna]
The antenna of this embodiment includes any one of the first to fourth composite magnetic bodies.
As one form of this antenna, there is an antenna loaded with the above composite magnetic material.
The method for loading the antenna with the composite magnetic body is not particularly limited, and the conductor such as a copper wire constituting the antenna (hereinafter referred to as “antenna conductor”) is covered with the composite magnetic body. What is necessary is just to load by a well-known method.

The type and shape of the antenna are not particularly limited, and a monopole antenna, a loop antenna, a helical antenna, a patch antenna, an F-type antenna, an L-type antenna, or the like is preferably used. Further, a matching circuit may be used in combination in order to reduce the size of the antenna.
For example, a monopole antenna or an L-shaped antenna can be obtained by sandwiching the above composite magnetic body into a rod-like or long plate-like shape around the antenna conductor.
The helical antenna can be obtained by winding a long and extremely thin antenna conductor made of copper wire or the like in a coil shape around a rod-shaped composite magnetic material obtained by processing the above-described composite magnetic material into a rod shape.
With these antennas, it is possible to obtain a small antenna having a length shorter than ¼ of the desired wavelength due to the wavelength shortening effect.

FIG. 8 is a schematic diagram showing a method of feeding a monopole antenna which is an example of the antenna of the present embodiment. The monopole antenna 61 has a rod-shaped antenna conductor 62 and a surface of the antenna conductor 62 embedded by embedding the antenna conductor 62. And a plate-like composite magnetic body 63 covered with
The monopole antenna 61 is connected to a ground plane 64 made of a conductor having a predetermined shape via a coaxial connector or the like, and an AC signal transmitter 66 is used so that the connection portion 65 that is an inner conductor of the coaxial connector or the like serves as a feeding point. It is connected.
In the same manner as described above, the antenna is connected to the ground plane 64 via a connector or the like, and the AC signal transmitter 66 is connected so that the connecting portion 65 serves as a feeding point. The connection portion 65 and the ground plane 64 serving as a feeding point are electrically insulated.

[Communication device]
The communication device of this embodiment includes the antenna described above.
The communication device is not particularly limited as long as it is a device that transmits, receives, or transmits / receives various information via electromagnetic waves. For example, personal computers, portable telephones, portable information terminals, multifunctional portable information terminals such as smartphones, communication devices such as PDAs (Personal Digital Assistants), various electronic devices such as audio devices, video devices, camera devices, etc. It is done.

In addition to the various devices described above, the communication device according to the present embodiment includes a communication device in which an auxiliary antenna provided with the antenna is mounted on various accessories (auxiliary tools) such as a protective cover attached to the various devices. .
In these communication devices, the antenna may be provided outside the communication device, or may be built in either.

Here, taking a portable telephone as an example of the communication device, various methods of attaching the antenna will be described.
FIG. 9 is a perspective view showing an example of a kind of mobile phone of the communication apparatus according to the present embodiment. The mobile phone 71 has a display function including a liquid crystal display, an organic EL display, or the like on the front surface of the casing 72. The display unit 73 is provided, and a ground plate (not shown) is provided on the back side of the display unit 73, and an antenna conductor 75 disposed in the rod-shaped monopole antenna 74 via a connector or the like is provided on the ground plate. The electronic circuit (not shown) of the portable telephone 71 is connected through this connection portion. The antenna conductor 75 of the monopole antenna 74 is covered with a composite magnetic body 76.

The monopole antenna 74 can be taken out from the casing 72 and can be stored in the casing 72. When communicating, the monopole antenna 74 is pulled out from the casing 72 as necessary to perform communication. When not communicating, the casing 72 It is designed to be pushed into the storage.
The monopole antenna 74 does not have to be rod-shaped and may be telescopic.
The monopole antenna 74 is preferably provided at a position that does not overlap the display unit 73 or the like in consideration of improving the antenna gain. In the case where the monopole antenna 74 is provided at a position overlapping with the display unit 73 and the like, it is preferable that the monopole antenna 74 and the display unit 73 are spaced from each other.

FIG. 10 is a perspective view showing another example of a kind of mobile phone of the communication apparatus of the present embodiment. The mobile phone 81 is a display comprising a liquid crystal display, an organic EL display, or the like on the front surface of the housing 82. A display portion 83 having a function is provided, and an external antenna terminal 84 is provided on the side surface. A connection terminal 86 provided on the side surface of the rod-shaped monopole antenna 85 is fitted into the external antenna terminal 84. The antenna conductor 87 disposed in the monopole antenna 85 is connected to a ground plate (not shown) provided on the back side of the display unit 83 via a connection terminal 86 and an external antenna terminal 84, and this connection The electronic circuit (not shown) of the portable telephone 81 is connected through the unit. In this monopole antenna 85, an antenna conductor 87 is covered with a composite magnetic body 88.
The portable telephone 81 can be attached and detached by inserting / removing the connection terminal 86 of the monopole antenna 85 to / from the external antenna terminal 84.

FIG. 11 is a partial perspective view showing a part of still another example of a mobile phone of a kind of the communication apparatus according to the present embodiment. The mobile phone 91 includes a liquid crystal display or an organic EL on the front surface of a housing 92. A ground plate 93 is provided on the back side of a display unit (not shown) having a display function such as a display, and an L-shaped antenna 94 is provided at a position that does not overlap with the ground plate 93 (in FIG. 22, above the ground plate 93). An antenna conductor 95 made of a conductor such as a copper wire disposed in the L-shaped antenna 94 is connected to the ground plane 93 via a connector or the like, and an electronic circuit (not shown) of the portable telephone 91 is connected via this connection portion. Is connected. In this L-shaped antenna 94, an antenna conductor 95 is covered with a composite magnetic body 96.

FIG. 12 is a partial perspective view showing a part of still another example of a mobile phone of a kind of the communication apparatus according to the present embodiment. The mobile phone 101 includes a liquid crystal display or an organic EL on the front surface of the housing 102. A ground plate 103 is provided on the back side of a display unit (not shown) having a display function such as a display, and a helical antenna 104 is provided at a position that does not overlap with the ground plate 103 (above the ground plate 103 in FIG. 23). A helical antenna conductor 106 wound around a rod-shaped composite magnetic body 105 of the helical antenna 104 is connected to the ground plate 103 via a connector or the like, and an electronic circuit (not shown) of the portable telephone 101 is connected via this connection portion. ) Is connected.
In the helical antenna 104, an antenna conductor 106 made of a conductor such as a copper wire is spirally wound so as to surround a rod-shaped composite magnetic body 105.

FIG. 13 is a perspective view showing an example of a mobile phone with a protective cover of a kind of the communication device of the present embodiment. The mobile phone 111 with a protective cover includes a mobile phone 112 and the mobile phone 112. The portable telephone 112 is provided with a display unit 115 having a display function including a liquid crystal display, an organic EL display, and the like on the front surface of the casing 114. The protective cover 113 is a kind of attached accessory. An external antenna terminal 116 connected to a ground plate (not shown) provided on the back side of the display unit 115 is provided on one side surface of the body 114.

On the other hand, the protective cover 113 is a deformable one made of a flexible resin or the like, and is provided so as to cover the peripheral edge and the back surface of the housing 114 excluding the display portion 113, and one side portion of the protective cover 113. Is provided with a dipole antenna 121, and an antenna conductor 122 made of a conductor such as a copper wire is covered with a composite magnetic body 123. The dipole antenna 121 is provided with a connection terminal 124 for connecting the dipole antenna 121 to the external antenna terminal 116.
The dipole antenna 121 includes two monopole antennas as a pair, and is preferably provided at a position that does not overlap with the display unit 115 when the protective cover 113 is attached to the portable telephone 112. Note that in the case where the protective cover 113 is provided at a position overlapping with the display portion 115, it is desirable that the thickness of the protective cover 113 is increased and the dipole antenna 121 and the display portion 115 are appropriately spaced inside the protective cover 113.

In this portable telephone 111 with a protective cover, a dipole antenna 121 is connected to a ground plate (not shown) provided on the back side of the display unit 115 via a connection terminal 124 and an external antenna terminal 116, An electronic circuit (not shown) of the portable telephone is connected.
In the portable telephone 111 with the protective cover, the connection terminal 124 of the protective cover 113 is inserted into the external antenna terminal 116 of the portable telephone 112, and the protective cover 113 is put on the portable telephone 112 while maintaining this state. Thus, the dipole antenna 121 can be connected to the mobile phone 112.
Further, the dipole antenna 121 can be detached from the portable telephone 112 by removing the protective cover 113 from the portable telephone 112.

FIG. 14 is a plan view showing another example of a portable telephone with a protective cover of the communication apparatus of this embodiment, and FIG. 15 is a cross-sectional view taken along the line AA in FIG. The mobile phone 131 includes a mobile phone 132 and a protective cover 133, and the mobile phone 132 is provided with a display unit 135 having a display function including a liquid crystal display or an organic EL display on the front surface of the housing 134. An external antenna terminal 136 is provided on the upper surface of the housing 134 for connection to a ground plate (not shown) provided on the back side of the display unit 135.

On the other hand, the protective cover 133 is made of a flexible resin or the like and is deformable, and is provided so as to cover the peripheral portion and the back surface of the casing 134. A spiral antenna 141 is provided on the back surface of the protective cover 133. Is provided. The spiral antenna 141 is obtained by coating a spiral antenna conductor 142 with a composite magnetic body 143, and the spiral antenna 141 is provided with a connection terminal 144 for connection to an external antenna terminal 136.
The spiral antenna 141 is preferably provided at a position that does not overlap the display unit 135 when the protective cover 133 is attached to the portable telephone 132. Note that in the case where the protective cover 133 is provided so as to overlap with the display portion 135, it is desirable that the thickness of the protective cover 133 is increased and the space between the spiral antenna 141 and the display portion 135 is appropriately set inside the protective cover 133.

In this portable telephone 131 with a protective cover, a spiral antenna 141 is connected to a ground plate (not shown) provided on the back side of the display unit 135 via a connection terminal 144 and an external antenna terminal 136. An electronic circuit (not shown) of the portable telephone is connected through the cable.
In the portable telephone 131 with the protective cover, the connection terminal 144 of the protective cover 133 is inserted into the external antenna terminal 136 of the portable telephone 132, and the protective cover 133 is put on the portable telephone 132 while maintaining this state. Thus, the spiral antenna 141 can be connected to the mobile phone 132.
Further, the spiral antenna 141 can be detached from the portable telephone 132 by removing the protective cover 133 from the portable telephone 132.

According to each of the above examples, since the mounted monopole antennas 74 and 85, the L-shaped antenna 94, the helical antenna 104, the dipole antenna 121, and the spiral antenna 141 are all small, the antenna is narrow in the portable telephone. A portable telephone with a high antenna gain can be obtained without being blocked by components other than the antenna, and can be placed in a space.
In particular, since the dipole antenna 61 and the spiral antenna 141 can be installed in accessories such as the protective covers 113 and 133, the auxiliary antenna is provided in the portable telephone without occupying the area in the portable telephone casing. And the performance of the antenna can be improved.

According to the composite magnetic body of this embodiment, the average thickness of the tabular magnetic particles is 0.01 μm or more and 0.5 μm or less, the average major axis is 0.05 μm or more and 10 μm or less, and the average aspect ratio (major axis / thickness). Therefore, the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz can be larger than 1 and the loss tangent tan δμ can be 0.1 or less. The reduction rate can be greatly increased.
Therefore, if this composite magnetic body is applied to a VHF band antenna, generation of eddy currents on the surface of the composite magnetic body can be prevented, and a reduction in the real part μr ′ of the complex permeability can be prevented. Further antenna miniaturization can be achieved.

According to the method for producing a composite magnetic body of the present embodiment, a slurry in which spherical magnetic particles having an average particle diameter of 0.5 μm or less are dispersed in a solution containing a surfactant and a dispersion medium can be sealed. The total volume of the slurry and the dispersion medium is filled so as to be the same as the volume in the container, and the slurry is stirred together with the dispersion medium in a sealed state to deform the spherical magnetic particles. And a first step of fusing to form flat magnetic particles, and a second step of dispersing and mixing the flat magnetic particles in a solution in which an insulating material is dissolved in a solvent to obtain a molding material. And a molding step of molding or applying the molding material on a substrate to obtain a molded body, and a third step including a drying / curing step of drying / curing the molded body. Frequency band up to 500MHz Real part .mu.r 'is large definitive complex permeability and the loss tangent tanδμ be 0.1 or less of the composite magnetic body of the complex permeability can be easily fabricated.

In addition, according to the composite magnetic body when the porosity of the composite magnetic body of the present embodiment is 20% or less, the value of the real part μr ′ of the complex permeability is improved and the real part εr ′ of the complex permittivity is improved. The value of can be kept almost unchanged. Therefore, electronic parts and electronic devices to which this composite magnetic body is applied can be reduced in size, and power loss due to impedance matching can be suppressed.
Further, when the loss tangent tan δμ of the complex dielectric constant from 70 MHz to 500 MHz is 0.05 or less and the loss tangent tan δε of the complex dielectric constant is 0.1 or less, the gain of the electronic component or electronic device can be improved. it can.

In addition, according to the composite magnetic body including the first resin having the cyclic structure in the main chain and the functional group that is polymerized in the monomer unit as the insulating material, the influence of the steric hindrance by the resin on the flat magnetic particles is reduced. can do. Therefore, it is possible to provide a composite magnetic body having a high real part μr ′ of complex permeability and excellent mechanical strength.
In addition, since a resin having a functional group that is polymerized by monomer units is used, the bonding of the resin becomes strong, and it is possible to have mechanical strength as a molded body sufficient for use in electronic parts and the like.

According to the method for producing a composite magnetic body of the present embodiment, a resin having a cyclic structure in the main chain and a functional group that is polymerized in monomer units, tabular magnetic particles, a solvent, and curing as necessary A step of mixing the agent to obtain a molding material, a step of applying a magnetic field to the molding material to orient the tabular magnetic particles, and a step of drying and curing the molded body in which the tabular magnetic particles are oriented. Therefore, a composite magnetic body having a high real part μr ′ of complex permeability and excellent mechanical strength can be easily produced.
Furthermore, the orientation of the flat magnetic particles in the coating film can be improved by applying a magnetic field to the coating film once or a plurality of times.

In addition, the composite magnetic material includes a first resin having a cyclic structure in the main chain as an insulating material and having a functional group that is polymerized in a monomer unit, and a second resin that imparts flexibility to the first resin. According to the body, the influence of the steric hindrance by the resin on the tabular magnetic particles can be reduced, the orientation of the tabular magnetic particles in one direction can be improved, and μr ′ can be increased.
Further, since the second resin imparts flexibility to the first resin, the flexibility and stretchability of the composite magnetic body itself can be improved.
Therefore, it is possible to provide a composite magnetic body having a high μr ′, excellent mechanical strength, soft enough to be wound on a roll, and excellent in productivity.

In addition, since the first resin having a functional group that is polymerized in monomer units is used, the resin bond becomes strong, and it has sufficient mechanical strength as a molded body for use in electronic parts and the like. it can.

Furthermore, since it has flexibility and stretchability even at a micro-level or nano-level size, it becomes easier for the resin to enter the gaps between the tabular magnetic particles, and causes a decrease in μr ′. Pore can be reduced.
Further, by using the first resin and the second resin in combination, the steric hindrance caused by the first resin can be alleviated. Therefore, pores generated between the resin and the resin or between the resin and the tabular magnetic particles. Can also be reduced.
As described above, a composite magnetic body having a high μr ′ can be provided.

According to the method for producing a composite magnetic body of the present embodiment, a first resin having a cyclic structure in the main chain and having a functional group that is polymerized in a monomer unit, and imparting flexibility to the first resin A second resin, flat magnetic particles, and a solvent are mixed to produce a molding material, a molding step of molding the molding material into a predetermined shape, and a magnetic field is applied to the obtained molding. Since it has an orientation step of applying and orienting the flat magnetic particles in the compact in one direction and a drying / curing step of drying / curing the oriented compact, the μr ′ is high and the mechanical strength is high. It is easy to produce a composite magnetic body that is excellent in flexibility, productivity, and productivity.
Furthermore, the orientation of the flat magnetic particles in the coating film can be improved by applying a magnetic field to the coating film once or a plurality of times. Therefore, a composite magnetic body having a high μr ′ can be produced.

According to the antenna of this embodiment, since the composite magnetic body of this embodiment is loaded and electromagnetic waves in the frequency band from 70 MHz to 500 MHz are transmitted, received, or transmitted / received, further miniaturization of the antenna is achieved. be able to. That is, it is possible to obtain a small antenna having a length shorter than ¼ of the desired wavelength due to the wavelength shortening effect.

Further, when the composite magnetic body having a porosity of 20% or less according to the present embodiment is provided, the real part μr ′ of the complex permeability is 7 or more and the real part εr of the complex dielectric constant in the frequency band from 70 MHz to 500 MHz. It is possible to obtain performances in which 'is 15 or more, (μr ′ · εr ′) ^−1/2 is 0.1 or less, and (μr ′ / εr ′) ^1/2 is 0.5 or more and 1 or less.
Therefore, it is possible to provide an antenna having a small radiation length shorter than ¼ of the desired wavelength due to the wavelength shortening effect, power loss due to impedance matching, and high radiation efficiency. Therefore, even with an electromagnetic wave having a long wavelength such as a VHF band such as multimedia broadcasting, a small antenna that can be received with the casing size of a portable telephone can be provided due to the wavelength shortening effect.

According to the communication device of the present embodiment, since the small antenna of the present embodiment is provided, there is a high degree of freedom in arranging the antenna in a place that is not easily affected by other electronic devices that block radio waves, and good transmission and reception are possible. A possible small communication device can be obtained.

[Monopole antenna]
FIG. 16A is a schematic diagram (perspective view) showing a monopole antenna according to one embodiment of the present invention, and FIG. 16B is a cross-sectional view taken along the line AA in FIG. 16A.
The monopole antenna 1620 of this embodiment includes a rod-shaped antenna conductor 1622 and a composite magnetic body 1621 of this embodiment that is coated on the surface of the antenna conductor 1622. In the case of this embodiment, as shown in FIG. 16B, a composite magnetic body 1621 having a square cross section is formed on the peripheral surface of a cylindrical antenna conductor 1622, and the monopole antenna has a quadrangular prism shape as a whole. As shown in FIG. 16A, the monopole antenna 1620 is typically connected to the center of a conductor ground plate 1624 having a predetermined size via a connector or the like, and an AC signal transmitter so that the connection portion 1626 serves as a feeding point. 1625 is connected.

The shape of the antenna conductor 1622 used for the monopole antenna 1620 is not particularly limited, and a known shape such as a linear rod antenna, a whip antenna, a curved helical antenna, or a meander antenna can be used. Among these, a linear antenna is preferable in that electrostatic capacitance is hardly generated between antenna conductors and a high antenna gain can be obtained.

Note that “linear” in the present embodiment means that the resonance part of the antenna is a straight rod or plate. Therefore, the shape of the linear monopole antenna 1620 may be not only a normal columnar shape but also a prismatic shape or an elongated flat plate shape. Similarly, the antenna conductor 1622 serving as the core material may be any one of a cylindrical shape, a prismatic shape, and a flat plate shape.

It is preferable to use a conductive metal or alloy as the antenna conductor 1622. Examples of such a metal include copper (Cu), silver (Ag), nickel (Ni), platinum (Pt), and gold (Au), and the alloy includes two or more selected from these. Metal alloys are preferred.

The cross-sectional shape of the antenna conductor 1622 is not particularly limited as long as it is of a size that can be mounted on a mobile terminal, and can be a square or round cross-sectional shape with a diameter D of about 0.5 mm to 2 mm, for example. .
Furthermore, since radio waves of 160 MHz to 222 MHz flow on the surface of the conductor, it is also effective to make the antenna conductor 1622 into a tape shape with a large surface area. The tape-shaped antenna conductor 1622 preferably has a width of 0.5 mm to 2 mm and a thickness of 0.05 to 0.2 mm.

The length L of the antenna conductor 1622 is not particularly limited as long as it can be easily mounted on a mobile terminal, and is preferably 40 mm or more and 200 mm or less, more preferably 50 mm or more and 100 mm or less. By setting the length L within the above range, the monopole antenna 1620 that can be easily mounted on a portable terminal and can be used in the frequency band of 160 MHz to 222 MHz can be obtained.

<Composite magnetic material>
Any of the above composite magnetic bodies may be used as the composite magnetic body 1621 of the present embodiment.

In the composite magnetic body 1621, the real part μr ′ of the complex permeability in the frequency band from 160 MHz to 222 MHz is preferably 3 or more, and more preferably 6 or more.
If the real part μr ′ of the complex permeability of the composite magnetic body 1621 is 3 or more, the coating thickness is 2.4 mm or more, so that even when the antenna conductor 1622 having a length of 200 mm is used, resonance occurs at a frequency of 200 MHz. A monopole antenna 1620 that can cause
If the complex magnetic permeability 16r ′ of the composite magnetic body 1621 is 6 or more, a further wavelength shortening effect can be obtained. Therefore, even if the coating thickness of the antenna conductor 1622 is reduced to 1.2 mm, the antenna having a length of 200 mm A monopole antenna 1620 that can resonate at a frequency of 200 MHz using the conductor 1622 can be obtained.

When the coating thickness d of the composite magnetic body 1621 is too thick, the antenna becomes thick, and it becomes difficult to mount it due to the configuration and design of the device of the mobile terminal. Therefore, practically, the coating thickness d by the composite magnetic material is in the range of 10 mm or less.
Note that the composite magnetic body 1621 and the antenna conductor 1622 do not need to be in close contact with each other. For example, the antenna conductor 1622 may be disposed inside the cylindrical composite magnetic body 1621 and covered in appearance.

In the composite magnetic body 1621 of this embodiment, the loss tangent tan δμ of the complex permeability in the frequency band from 160 MHz to 222 MHz is preferably 0.05 or less. By setting tan δμ to 0.05 or less, it is possible to prevent a decrease in antenna gain due to loss of signals in the frequency band from 160 MHz to 222 MHz.

<Manufacturing method of monopole antenna>
The manufacturing method of the monopole antenna 1620 of the present embodiment includes a first step of producing the above-mentioned flat magnetic particles by processing spherical magnetic particles into a flat plate shape, and the flat magnetic particles as an insulating material. A second step of mixing to form a molding material and a third step of coating the antenna conductor with the molding material containing the flat magnetic particles are provided.

Hereinafter, each process will be described.

<First step>
Since the first step for producing the tabular magnetic particles is exactly the same as the first step described in the first method for producing a composite magnetic body, the description thereof is omitted.

<Second step>
Next, in the second step, the tabular magnetic particles are dispersed and mixed in a solution obtained by dissolving an insulating material in a solvent to obtain a molding material. When this molding material is solidified, a composite magnetic body 1621 is obtained in which tabular magnetic particles are dispersed in an insulating material.

The insulating material is not particularly limited as long as it is an insulating material. However, when the composite magnetic body of the present embodiment is used as an antenna for a mobile phone or an antenna for a portable information terminal, the mechanical strength is high and the hygroscopic property is high. It is preferable that it is low and it is excellent in shape workability. Examples of such an insulating material include polyimide resin, polybenzoxazole resin, polyphenylene resin, polybenzocyclobutene resin, polyarylene ether resin, polysiloxane resin, epoxy resin, polyester resin, fluorine resin, polyolefin resin, polycyclohexane. Thermosetting resins or thermoplastic resins such as olefin resins, cyanate resins, polyphenylene ether resins, norbornene resins, ABS resins, and polystyrene resins are preferably used. These resins may be used alone or in combination of two or more.
Especially, as a thermosetting resin, the epoxy resin excellent in mechanical strength and shape workability is preferable, and a polyphenylene resin and an ABS resin are preferable as a thermoplastic resin.
In addition, what is necessary is just to select suitably the kind, quantity, etc. of a hardening | curing agent with respect to the kind of resin to be used.

The solvent is not particularly limited as long as it can dissolve the resin. Examples of the solvent include alcohols such as methanol, ethanol, 2-propanol, butanol, and octanol, ethyl acetate, acetic acid, and the like. Butyl, ethyl lactate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, esters such as γ-butyrolactone, diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol Ethers such as monobutyl ether (butyl cellosolve), diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, acetone, methyl ether Preferred are ketones such as ruketone, methyl isobutyl ketone, acetylacetone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene, and amides such as dimethylformamide, N, N-dimethylacetoacetamide and N-methylpyrrolidone. These solvents may be used alone or in combination of two or more.

The content of the flat magnetic particles in the molding material is 20% by volume or more and 50% by volume or less with respect to the volume when the volatile components in the molding material are cured to form the composite magnetic body 1621. Preferably, 30 volume% or more and 40 volume% or less are more preferable.
If the content of tabular magnetic particles is less than 20% by volume, the amount of tabular magnetic particles is too small and the magnetic permeability of the composite magnetic body 1621 decreases. It is preferable because there are too many body particles, the fluidity of the molding material is lowered, and as a result, the orientation of the tabular magnetic particles in the molding material is lowered and the magnetic permeability of the composite magnetic body 1621 may be lowered. Absent.

The method for dispersing and mixing the flat magnetic particles in the insulating material is not particularly limited, but a stirring device such as a planetary mill, a sand mill, or a ball mill can be used. A kneading apparatus such as a pressure kneader, a twin-screw kneader, or a blast mill can also be used. When a thermoplastic resin is used, it may be heated as necessary.

<Third step>
In the third step, the molding material produced in the second step is applied to the outer peripheral surface of the antenna conductor 1622 and cured to obtain the composite magnetic body 1621. Thereby, the monopole antenna 1620 of this embodiment can be obtained.

The method of applying the molding material to the antenna conductor 1622 and covering the composite magnetic body 1621 is not particularly limited as long as it can cover the composite magnetic body 1621 having a desired coating thickness d.
The coating thickness d of the composite magnetic body 1621 is determined based on the length L of the antenna conductor and the magnetic permeability of the composite magnetic body 1621. Examples of a method for coating the composite magnetic body 1621 include a method in which the antenna conductor 1622 is molded and cured so as to be sandwiched inside the molding material by a heating press method, an injection molding method, or an extrusion molding method. When a thermosetting resin is used, it is preferable to cure the molding material by heat treatment or heat press treatment in a reducing atmosphere or in vacuum.

In addition, a plurality of the molding materials formed into a sheet shape or a film shape may be laminated so as to have a desired coating thickness, and the antenna conductor 1622 may be sandwiched to cover the molding material. As a method for molding the molding material into a sheet or film, for example, a hot press method, a doctor blade method, an injection molding method, or the like is preferably used.
Among these methods, the hot press molding method in which the flat magnetic particles are easily oriented in the insulating material is preferred. In order to adjust the viscosity at the time of stretching, it is also preferable to add a plasticizer and perform surface treatment of the tabular magnetic particles. If necessary, it is preferable to perform a treatment for orienting the tabular magnetic particles by orientation of a magnetic field in a state where the fluidity is maintained by heating.

The direction in which the tabular magnetic particles are oriented is preferably such that the magnetic field generated in the antenna 1620 passes through the tabular magnetic particles for a long distance to obtain a wavelength shortening effect. That is, it is preferable to align the antenna conductor 1622 so that the direction around the axis (circumferential direction) and the long axis of the tabular magnetic particles are substantially parallel.

In addition, when it is necessary to adjust the viscosity of the molding material in forming the composite magnetic body 1621, the molding may be performed after volatilizing and concentrating the solvent contained in the molding material.
Further, when the orientation treatment of the tabular magnetic particles is necessary, after molding the molding material so that the antenna conductor 1622 is sandwiched inside, a magnetic field is applied to the molding material before drying the tabular magnetic body. The particles may be oriented so that the direction around the axis of the antenna conductor 1622 (circumferential direction) and the major axis of the tabular magnetic particles are substantially parallel.

As described above, according to the monopole antenna of the present embodiment, the antenna conductor is covered with the composite magnetic material in which the flat magnetic particles are dispersed in the insulating material, so that it can be mounted on a portable terminal. The size can be reduced so much that it can be used in a low frequency band of 160 MHz to 222 MHz.

When the real part μr ′ of the complex permeability in the frequency band from 160 MHz to 222 MHz is 3 or more, the antenna conductor is 200 mm or less by covering the composite magnetic body 1621 of this embodiment with 2.4 mm or more. However, it can resonate with a frequency of 200 MHz.

When the real part μr ′ of the complex permeability in the frequency band from 160 MHz to 222 MHz is 6 or more, the antenna conductor is 200 mm or less by covering the composite magnetic body 1621 of this embodiment with 1.2 mm or more. However, it can resonate with a frequency of 200 MHz.

The linear monopole antenna 1620 of the present embodiment can be further miniaturized by using it together with a matching circuit.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.
Various characteristics in each example were evaluated by the following methods.
(1) Observation of tabular magnetic particles The particles were observed with a scanning electron microscope S-4000 (manufactured by Hitachi High-Tech).
(3) Measurement of electromagnetic characteristics (μr ′, μr ″, tan δμ, εr ′, εr ″, tanδε) Permeability measuring device Material analyzer E4991A type (manufactured by Agilent Technologies) at room temperature in air (25 ° C.) Measured in Based on these μr ′ and εr ′, (μr ′ · εr ′) ^−1/2 and (μr ′ / εr ′) ^1/2 were calculated.
(4) Porosity The dimensions and mass of the composite magnetic material were measured, and the actual density was calculated based on these measured values.
On the other hand, the theoretical density (≈measured density) of the resin was calculated from these measured values by measuring the dimensions and mass of the cured body of resin alone. The theoretical density of the tabular magnetic particles was the X-ray theoretical density determined from the X-ray diffraction pattern of the tabular magnetic particles.
These values were substituted into equation (4) to calculate the porosity of the composite magnetic material.

[Example 1]
200 g of permalloy (trade name) magnetic particles containing 4% by mass of zinc and having an average particle diameter of 0.25 μm are mixed in a mixed solution of 400 g of xylene and 400 g of isopropyl alcohol in which a nitrogen-containing graft polymer is dissolved as a surfactant. Was made.
Next, a sand mill Ultra Apex Mill UAM-5 (manufactured by Kotobuki Industries Co., Ltd.) having a circulation volume of 5 L and a container volume as shown in FIG. 2 was used as the closed container, and an average particle diameter of 200 μm was used as a dispersion medium in the closed container. Zirconia beads were charged, and then the above slurry was charged to fill the sealed container. Here, piping was made so that the slurry discharged from the sealed container was charged again and circulated.

In this state, until the residence time of the slurry in the sealed container reached 20 minutes, stirring was performed at a rotational speed at which the flow velocity at the outermost periphery in the sealed container was 10 m / second, to produce flat magnetic particles.
Next, after drying the obtained tabular magnetic particles to dissipate the solvent, a predetermined amount of the tabular magnetic particles is added to a resin varnish obtained by diluting the epoxy resin to a solid content ratio of 40%. Added and mixed with stirring.

The obtained molding material was molded into a square film so as to be 30 mm square and 100 μm thick after curing by the doctor blade method.
Next, this film was dried at 90 ° C. in the air for 1 hour to form a dry film, and then press fired in a reduced pressure press. The press conditions were as follows: normal pressure was raised to 130 ° C. in 20 minutes, then 2 MPa pressure was applied and held for 5 minutes, then heated to 160 ° C. and held for 40 minutes to cure the resin, 30 mm square A square film-like composite magnetic body having a thickness of 50 μm was obtained.

When the complex permeability of this composite magnetic material was measured with a material analyzer, the real part μr ′ of the complex permeability at 90 MHz was 13, the loss tangent tan δμ was 0.02, and the real part μr ′ of the complex permeability at 220 MHz was 13. The loss tangent tan δμ was 0.04.
Further, when the shape of the composite magnetic material was observed with a scanning electron microscope (SEM), the average thickness of 50 tabular magnetic particles was 0.08 μm, the average major axis was 0.5 μm, and the average aspect ratio was 6.25. In addition, spherical magnetic particles and magnetic particles having a thickness of 0.01 μm or more and 0.5 μm or less, a major axis of 0.05 μm or more and 10 μm or less, and an aspect ratio of 5 or more were not substantially observed.
FIG. 17 shows the complex permeability (real part μr ′ and imaginary part μr ″) and loss tangent (tan δμ) of this composite magnetic body, and FIG. 18 shows the scanning electron microscope (SEM) image of this composite magnetic body. Show.

[Comparative Example 1]
20 g of permalloy (trade name) magnetic particles containing 4% by mass of zinc and having an average particle diameter of 0.25 μm are mixed in a mixed solution of 40 g of xylene and 40 g of isopropyl alcohol in which a nitrogen-containing graft polymer is dissolved as a surfactant. Was made.
Next, an upper open-type sand mill as shown in FIG. 1 was used as an open container, and zirconia beads having an average particle diameter of 200 μm were charged as a dispersion medium into the vessel of the open container, and then the above slurry was charged. . Here, magnetic particles were prepared by stirring for 30 minutes at a rotational speed at which the flow velocity at the outermost periphery in the vessel was 10 m / sec.

Using the obtained magnetic particles, a film-like composite magnetic material of Comparative Example 1 was obtained in the same manner as in Example 1.
When the complex magnetic permeability of this composite magnetic material was measured by a material analyzer, the real part μr ′ of the complex permeability at 90 MHz was 2.6, the loss tangent tan δμ was 0.09, and the real part μr of the complex permeability at 220 MHz. 'Was 2.8 and the loss tangent tan δμ was 0.11.
Further, when the shape of the composite magnetic material was observed with a scanning electron microscope (SEM), the magnetic particles were irregularly overlapped with each other, and there were many particles having a thickness of 0.5 μm or more. I understood that. The major axis and aspect ratio were also nonuniform.
FIG. 19 shows the complex magnetic permeability (real part μr ′ and imaginary part μr ″) and loss tangent (tan δμ) of this composite magnetic body, and FIG. 20 shows the scanning electron microscope (SEM) image of this composite magnetic body. Show.

[Example 2]
Twelve dry films having a length of 250 mm, a width of 30 mm, and a thickness of 60 μm were produced in the same manner as in Example 1.
Next, these dry films were laminated, and a copper wire having a diameter of 0.6 mm and a length of 250 mm was sandwiched between the sixth and seventh sheets as an antenna wire. Press firing is performed under the same conditions, and an antenna conductor 63 made of copper wire is contained in a composite magnetic body 63 made of a dry film laminate having a length of 250 mm, a width of 30 mm, and a thickness of 0.8 mm as shown in FIG. A monopole antenna 61 in which is inserted is manufactured.

Next, this monopole antenna 21 was connected to the center of a 500 mm square conductor ground plate 64, and 50 Ω was fed by an AC signal oscillator 66 using the connection point 65 as a feeding point.
Here, the resonance frequency of the monopole antenna 21 was measured, and for comparison, the resonance frequency of only a copper wire having a diameter of 0.6 mm and a length of 250 mm was measured.
As a result, the resonance frequency is 273 MHz only for the copper wire, whereas the monopole antenna loaded with the composite magnetic material of Example 2 is 180 MHz, and the shortening rate converted to the wavelength is about 66%. It was. From this result, it was found that the length of the 180 MHz antenna in the VHF band was reduced by about 34% by loading the composite magnetic material of the present invention.

[Example 3]
Dicyclopentadiene type epoxy resin EPICLON HP-7200L (manufactured by DIC Corporation), epoxy resin as curing agent and 1% by mass of 1-isobutyl-2-methylimidazole based on the total amount of curing agent, resin and curing agent, The average major axis is 2.5 μm, the average thickness is 0.3 μm, and the average is made of a Ni—Fe—Zn alloy of 40% by volume of Ni 75% by mass—Fe 20% by mass—Zn 5% by mass with respect to the total amount of tabular magnetic particles A plate-like magnetic particle having an aspect ratio of 8.3, 40% by mass of cyclohexanone with respect to the total mass of the plate-like magnetic particle, resin, and curing agent are put into a planetary stirrer and mixed for 15 minutes to form a slurry. A shaped molding material was obtained. The molding material had a viscosity of 0.4 Pa · S.

Next, the molding material was molded on a polyethylene terephthalate (PET) film with a bar coater, and sheet molding was performed so that the length was 50 mm × width 50 mm × thickness 0.1 mm.
After forming the sheet, a 900 gauss magnetic field was applied to the surface of the sheet in the horizontal direction for 6 minutes. Subsequently, it was air-dried by applying hot air of 80 ° C. Next, after applying a press pressure of 10 MPa at 110 ° C., which is the softening point of the resin, a curing reaction was carried out at 160 ° C. for 2 hours to obtain a composite magnetic body of Example 3.

Table 1 shows the porosity of the composite magnetic material of Example 3 and the magnetic characteristics obtained from the material analyzer at 200 MHz.
Further, the real part μr ′ and tan δμ of the complex permeability from 10 MHz to 1 GHz of the composite magnetic body of Example 3 are shown in FIG. 21, and the real part εr ′ and tan δε of the complex dielectric constant are shown in FIG.

[Example 4]
Instead of dicyclopentadiene type resin, use a resin in which dicyclopentadiene type resin and liquid epoxy resin Rikaresin BPO-20 (manufactured by Shin Nippon Rika Co., Ltd.) are mixed at a mass ratio of 85:15, and further press pressure is applied. A composite magnetic body of Example 4 was obtained according to Example 3 except that the temperature at that time was 160 ° C.

Table 1 shows the porosity of the composite magnetic material of Example 4 and the magnetic characteristics obtained from the material analyzer at 200 MHz.
In addition, FIG. 23 shows real parts μr ′ and tan δμ of complex permeability from 10 MHz to 1 GHz of the composite magnetic body of Example 4, and FIG. 24 shows real parts εr ′ and tan δε of complex permittivity, respectively.

[Example 5]
A composite magnetic body of Example 5 was obtained according to Example 3 except that the mixing time in the planetary stirrer was changed from 15 minutes to 5 minutes when obtaining the slurry-like molding material.
Table 1 shows the results of the magnetic properties obtained from the porosity of the composite magnetic material and the material analyzer at 200 MHz.

[Example 6]
A composite magnetic body of Example 6 was obtained according to Example 3 except that the temperature at which the compact was pressed was 160 ° C.
Table 1 shows the results of the magnetic properties obtained from the porosity of the composite magnetic material and the material analyzer at 200 MHz.

[Comparative Example 2]
Instead of tabular magnetic particles having an average major axis of 2.5 μm, an average thickness of 0.3 μm, and an average aspect ratio of 8.3, the average major axis is 1.2 μm, the average thickness is 0.3 μm, and the average aspect ratio is 4 A composite magnetic material of Comparative Example 2 was obtained according to Example 3 except that the magnetic particles were used.
Table 1 shows the results of the magnetic properties obtained from the porosity of the composite magnetic material and the material analyzer at 200 MHz.

According to Table 1, the composite magnetic bodies of Examples 3 and 4 had a porosity as small as 20% or less as compared with the composite magnetic bodies of Examples 5 and 6. Therefore, it was confirmed that the composite magnetic bodies of Examples 3 and 4 have a larger μr ′ but have almost the same εr ′ as compared with the composite magnetic bodies of Examples 5 and 6.
In Comparative Example 2, since the magnetic particles having an average aspect ratio of less than 5 are used even when the porosity of the composite magnetic material is 20% or less, the μr ′ of the composite magnetic material is small, and the electronic components and electronic devices are small. It was confirmed that sufficient μr ′ could not be obtained.

[Example 7]
Dicyclopentadiene type epoxy resin EPICLON HP-7200L (manufactured by DIC Corporation), epoxy resin as curing agent and 1% by mass of 1-isobutyl-2-methylimidazole based on the total amount of curing agent, resin and curing agent, The average major axis is 2.5 μm, the average thickness is 0.3 μm, and the average aspect ratio is 8 μm. 3. Flat magnetic particles having an average coercive force of 35 oersted (Oe) and cyclohexanone were put into a planetary stirrer and mixed for 5 minutes to obtain a slurry-like molding material. The molding material had a viscosity of 0.4 Pa · S.

Next, the molding material was molded on a polyethylene terephthalate (PET) film with a bar coater, and sheet molding was performed so that the length was 50 mm × width 50 mm × thickness 0.1 mm.
After forming the sheet, the sheet was fed to the orientation device 11 shown in FIG. 3 at a speed of 2 m / min, and a magnetic field of 1200 gauss was applied. Subsequently, 80 degreeC warm air was applied and air-dried, and also hardening reaction was performed at 160 degreeC for 2 hours, and the composite magnetic body of Example 7 was obtained.

Using a scanning electron microscope (SEM), the angle formed by the long axis direction of the tabular magnetic particles with respect to the direction (orientation direction) horizontal to the sheet surface is measured using the scanning electron microscope (SEM). The inclination with respect to the horizontal direction was measured for 50 tabular magnetic particles. As a result, the average value of the 50 tilts was 8.2 degrees, and it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
In addition, μr ′ of this composite magnetic body at room temperature and 200 MHz in the atmosphere was 8.5.

[Example 8]
The composite magnetic body of Example 8 is obtained in the same manner as in Example 7 except that the content of the tabular magnetic particles is 40% by volume with respect to the total amount of the resin, the curing agent, and the tabular magnetic particles. It was.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 7, the average value of the inclination was 8.5 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
Further, the complex permeability of this composite magnetic material was measured in the same manner as in Example 7. As a result, μr ′ at room temperature and 200 MHz in the atmosphere was 9.3.

[Example 9]
Instead of mixing 1% by mass of 1-isobutyl-2-methylimidazole as a curing agent with respect to the total amount of the epoxy resin, phenol novolac resin TD-2131 (manufactured by DIC Corporation) is used with respect to the total amount of the epoxy resin, etc. A composite magnetic body of Example 9 was obtained in the same manner as Example 7 except that the amount was mixed.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 7, the average value of the inclination was 8.6 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
Further, the complex permeability of this composite magnetic material was measured in the same manner as in Example 7. As a result, μr ′ at room temperature and 200 MHz in the atmosphere was 8.3.

[Example 10]
A composite magnetic body of Example 10 was obtained in the same manner as in Example 7 except that the magnetic field applied to the sheet in Example 7 was changed from 1200 gauss to 1000 gauss.
The inclination of the tabular magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 7. The average value of the inclination was 12.5 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
The complex magnetic permeability of this composite magnetic material was measured in the same manner as in Example 7. As a result, μr ′ at room temperature and 200 MHz in the atmosphere was 7.7.

[Example 11]
A composite magnetic body of Example 11 was obtained in the same manner as in Example 7 except that the magnetic field applied to the sheet in Example 7 was changed from 1200 gauss to 900 gauss.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the direction horizontal to the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 7, the average value of the inclination was 17.9 degrees. Thus, it was confirmed that the tabular magnetic particles were generally oriented in the horizontal direction on the sheet surface.
The complex magnetic permeability of this composite magnetic material was measured in the same manner as in Example 7. As a result, μr ′ at room temperature and 200 MHz in the atmosphere was 7.2.

[Example 12]
In Example 8, after forming the sheet, instead of the orientation device 11 shown in FIG. 3, this sheet was fed to the orientation device 21 shown in FIG. 4 at a speed of 2 m / min, and a 900 gauss magnetic field was applied. A composite magnetic body of Example 12 was obtained in the same manner except for the above.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 7, the average value of the inclination was 16.4 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
In addition, this composite magnetic material had a μr ′ of 7.5 at 200 MHz in the air at room temperature.

[Example 13]
In Example 9, after sheet forming, instead of the orientation device 11 shown in FIG. 3, this sheet was fed to the orientation device 21 shown in FIG. 4 at a speed of 1 m / min, and a 900 gauss magnetic field was applied. A composite magnetic body of Example 13 was obtained in the same manner except for the above.
When the inclination of the flat magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 flat magnetic particles in the same manner as in Example 7, the average value of the inclination was 17.0 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
In addition, μr ′ of this composite magnetic material in the atmosphere at room temperature and 200 MHz was 7.3.

[Example 14]
In Example 12, after sheet forming, instead of the orientation device 21 shown in FIG. 4, this sheet is fed to the orientation device 31 shown in FIG. 5 at a speed of 2 m / min, and 300 gauss per pair of magnets. A magnetic field was applied. Subsequently, 80 degreeC warm air was applied and air-dried, and also hardening reaction was performed at 160 degreeC for 2 hours, and the composite magnetic body of Example 14 was obtained.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 7, the average value of the inclination was 8.3 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
Further, this composite magnetic body had a μr ′ of 9.0 at 200 MHz in the air at room temperature.

[Example 15]
Dicyclopentadiene type epoxy resin EPICLON HP-7200L (manufactured by DIC Corporation) was replaced with bisphenol type epoxy resin 1256 (manufactured by Mitsubishi Chemical Corporation) in the same manner as in Example 7, but the composite magnetic body of Example 15 Got.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 7, the average value of the inclination was 21.5 degrees. These tabular magnetic particles were not aligned in one direction, and it was confirmed that the orientation was lowered.
The complex permeability of this composite magnetic material was measured in the same manner as in Example 7. As a result, μr ′ at room temperature and 200 MHz in the atmosphere was 5.6.

[Example 16]
Dicyclopentadiene-type epoxy resin EPICLON HP-7200L (manufactured by DIC Corporation) and bisphenol A bis (propylene glycol glycidyl ether) ether-type liquid epoxy resin Rical Resin BPO-20 (manufactured by Shin Nippon Rika) 10 mass% was mixed with respect to the mass, and the epoxy resin mixture was obtained.
Next, 1 wt% 1-isobutyl-2-methylimidazole with respect to the total weight of the epoxy resin mixture and the curing agent as a curing agent, the epoxy resin mixture, the curing agent, and the tabular magnetic particles are added to the epoxy resin mixture. A flat magnetic body having an average major axis of 2.5 μm, an average thickness of 0.3 μm, and an average aspect ratio of 8.3, comprising an alloy of 40% by volume of Ni 75% by mass—Fe 20% by mass—Zn 5% by mass. 40 mass% of cyclohexanone with respect to the total mass of the particles, the epoxy resin mixture, the curing agent, and the flat magnetic particles was put into a planetary stirrer and mixed for 5 minutes to obtain a slurry-like molding material.

Subsequently, this slurry-like molding material was formed on a polyethylene terephthalate (PET) film by a bar coater, and then molded into a sheet of 100 mm in length, 200 mm in width, and 0.1 mm in thickness. A film with a sheet was obtained.
Next, after forming the sheet, a 900 gauss magnetic field was applied to the formed sheet for 6 minutes in the horizontal direction. Next, after 80 ° C. warm air was applied and air-dried, the molded body sheet was peeled off from the PET film, and after applying a press pressure of 10 MPa at 110 ° C., a curing reaction was performed at 160 ° C. for 2 hours, A 100 mm × 200 mm sheet-shaped composite magnetic body of Example 16 was obtained. When the sheet-shaped composite magnetic body was peeled from the PET film, the sheet-shaped composite magnetic body was not damaged.

Next, as a result of measuring the electromagnetic characteristics and the porosity of the composite magnetic body, the real part μr ′ of the complex magnetic permeability at 200 MHz of the composite magnetic substance is 8.9, and the real part εr ′ of the complex dielectric constant is 30.4. The porosity was 19%.

[Example 17]
Instead of applying a 900 gauss magnetic field in the horizontal direction to the compact sheet for 6 minutes, a 1200 gauss magnetic field is applied while feeding the compact sheet at a speed of 2 m / min using the orientation device 11 shown in FIG. Furthermore, in the drying / curing process, after applying a pressing pressure of 10 MPa at 110 ° C., instead of performing a curing reaction at 160 ° C. for 2 hours, curing is performed at 160 ° C. for 2 hours without applying a pressing pressure. A composite magnetic body of Example 17 was obtained in the same manner as Example 16 except that the reaction was performed.

Here, when the obtained sheet-shaped composite magnetic body was peeled from the PET film, the sheet-shaped composite magnetic body was not damaged.
Next, when the magnetic properties and the porosity of the composite magnetic material were measured, the real part μr ′ of the complex magnetic permeability at 200 MHz of the composite magnetic substance was 9.0, and the real part εr ′ of the complex dielectric constant was 27.1. The porosity was 19%.

[Example 18]
Except for mixing 10% by mass of the liquid epoxy resin Rica Resin BPO-20 with the dicyclopentadiene type epoxy resin EPICLON HP-7200L, the same procedure as in Example 15 was carried out except that 20% by mass of the liquid epoxy resin Rica Resin BPO-20 was mixed. Similarly, a composite magnetic material of Example 18 was obtained.

Here, when the obtained sheet-shaped composite magnetic body was peeled from the PET film, the sheet-shaped composite magnetic body was not damaged.
Next, when the magnetic properties and the porosity of the composite magnetic material were measured, the real part μr ′ of the complex permeability at 200 MHz of the composite magnetic substance was 9.3, and the real part εr ′ of the complex dielectric constant was 31.0. The porosity was 11%.

Further, the real part μr ′ of the complex permeability and the loss tangent tan δμ of the complex permeability in the frequency band of 70 to 1000 MHz of this composite magnetic material were measured with a material analyzer at room temperature (25 ° C.) in the atmosphere. These measurement results are shown in FIG.
According to FIG. 25, the real part μr ′ of the complex permeability in the frequency band of 70 to 1000 MHz is 7 or more.

[Example 19]
The same procedure as in Example 16 was performed except that bisphenol A diglycidyl ether type epoxy resin Adeka Resin EP-4010S (manufactured by Adeka) was used instead of the bisphenol A bis (propylene glycol glycidyl ether) ether type liquid epoxy resin. The composite magnetic material of Example 19 was obtained.

Here, when the obtained sheet-shaped composite magnetic body was peeled from the PET film, the sheet-shaped composite magnetic body was not damaged.
Next, when the magnetic properties and the porosity of the composite magnetic material were measured, the real part μr ′ of the complex magnetic permeability at 200 MHz of the composite magnetic substance was 9.3, and the real part εr ′ of the complex dielectric constant was 29.7. The porosity was 19%.

[Example 20]
Instead of mixing 10% by mass of bisphenol A bis (propylene glycol glycidyl ether) ether type liquid epoxy resin Ricaresin BPO-20, 20% by mass of bisphenol A diglycidyl ether type epoxy resin Adeka Resin EP-4010S (manufactured by Adeka) was mixed. Except for this, the composite magnetic body of Example 20 was obtained in the same manner as Example 16.

Here, when the obtained sheet-shaped composite magnetic body was peeled from the PET film, the sheet-shaped composite magnetic body was not damaged.
Next, when the magnetic properties and the porosity of the composite magnetic material were measured, the real part μr ′ of the complex magnetic permeability at 200 MHz of the composite magnetic substance was 9.5, and the real part εr ′ of the complex dielectric constant was 28.9. The porosity was 12%.

[Example 21]
Instead of applying a 900 gauss magnetic field in the horizontal direction to the green body sheet for 6 minutes, the green body sheet is fed to the orientation device 21 shown in FIG. 4 at a speed of 2 m / min, and a 900 gauss magnetic field is applied to the green body sheet. A composite magnetic body of Example 21 was obtained in the same manner as Example 16 except that the voltage was applied.

Here, when the obtained sheet-shaped composite magnetic body was peeled from the PET film, the sheet-shaped composite magnetic body was not damaged.
Next, the magnetic properties and porosity of the composite magnetic material were measured in the same manner as in Example 16. As a result, the real part μr ′ of the complex magnetic permeability at 200 MHz of the composite magnetic substance was 7.3, and the real part εr of the complex dielectric constant was 'Was 22.8 and the porosity was 19%.

[Example 22]
Instead of applying a 900 gauss magnetic field in the horizontal direction to the compact sheet for 6 minutes, the compact sheet is fed to the orientation device 31 shown in FIG. 5 at a speed of 2 m / min, and a 300 gauss magnetic field for each pair of magnets. A composite magnetic body of Example 22 was obtained in the same manner as Example 16 except that was applied.

Here, when the obtained sheet-shaped composite magnetic body was peeled from the PET film, the sheet-shaped composite magnetic body was not damaged.
Next, the magnetic properties and the porosity of this composite magnetic material were measured in the same manner as in Example 16. As a result, the real part μr ′ of the complex magnetic permeability at 200 MHz of the composite magnetic substance was 9.0, and the real part εr of the complex dielectric constant was 'Was 30.4 and the porosity was 19%.

[Example 23]
Example 16 Except that instead of mixing 10% by mass of the liquid epoxy resin Licarresin BPO-20 with the dicyclopentadiene type epoxy resin EPICLON HP-7200L, 40% by mass of the liquid epoxy resin Licur Resin BPO-20 was mixed. In the same manner as described above, the composite magnetic body of Example 23 was obtained.

Here, when the obtained sheet-shaped composite magnetic body was peeled from the PET film, the sheet-shaped composite magnetic body was not damaged.
Next, when the magnetic properties and the porosity of the composite magnetic material were measured, the real part μr ′ of the complex permeability at 200 MHz of the composite magnetic substance was 7.5, and the real part εr ′ of the complex dielectric constant was 23.9. The porosity was 9%.

[Example 24]
A composite magnetic material of Example 24 was obtained in the same manner as in Example 21 except that the liquid epoxy resin Ricar Resin BPO-20 was not mixed with dicyclopentadiene type epoxy resin EPICLON HP-7200L.

Here, when trying to peel the obtained sheet-shaped composite magnetic body from the PET film, the sheet-shaped composite magnetic body could not be peeled cleanly and was damaged, resulting in a sheet-shaped composite magnetic body of 100 mm × 200 mm × 0.1 mm. Could not get.
Therefore, the broken pieces of the composite magnetic material were subjected to a curing reaction at 160 ° C. for 2 hours, and the magnetic properties and the porosity of the obtained piece-like composite magnetic material were measured in the same manner as in Example 18. The real part μr ′ of the complex magnetic permeability at 200 MHz of the composite magnetic material was 7.0, the real part εr ′ of the complex dielectric constant was 32.4, and the porosity was 26%.

[Example 25]
Flat magnetic particles (Ni 76% by mass—Fe 20% by mass—Zn 4% by mass) having an average thickness of 0.19 μm, an average major axis of 1.63 μm, and an average aspect ratio of 8.6 were dispersed in an epoxy resin to obtain a molding material. . The obtained molding material was put into a mold, molded, and thermally cured to obtain a composite magnetic body.

The composite magnetic body was coated on an antenna conductor with a thickness of 1.7 mm to produce a square pole monopole antenna shown in FIG. 16A. This monopole antenna resonated at 180 MHz when the antenna length was 200 mm, resonated at a frequency of 180 MHz or more when the antenna length was shorter than 200 mm, and resonated at 200 MHz when the antenna length was 180 mm. The average gain of this antenna in the XZ plane in FIG. 16A was −5.5 dBd. FIG. 26 shows the measurement results of the real part μr ′ and the loss tangent tan δμ of the complex magnetic permeability of the composite magnetic body. The real part μr ′ of the complex permeability at 160 to 222 MHz of the obtained composite magnetic body was 6 or more, and the loss tangent tan δμ of the complex permeability was 0.05 or less.

[Example 26]
A monopole antenna of Example 26 was produced in the same manner as in Example 25 except that the coating thickness of the composite magnetic material was 2.5 mm. This monopole antenna resonated at 120 MHz when the antenna length was 200 mm, resonated at a frequency of 120 MHz or more when the antenna length was shorter than 200 mm, and resonated at 200 MHz when 150 mm. The average gain of this antenna in the XZ plane was −6.5 dBd.

[Example 27]
Plate-like magnetic particles (Ni 76 mass% —Fe 20 mass% —Zn 4 mass%) having an average thickness of 0.35 μm, an average major axis of 2.49 μm, and an average aspect ratio of 7.3 were dispersed in an epoxy resin to obtain a molding material. . This molding material was put into a mold, molded, and thermally cured to obtain a composite magnetic body. The composite magnetic body was covered with a thickness of 2.5 mm around the rod-shaped antenna conductor to produce a quadrangular prism-shaped monopole antenna shown in FIG. 16A.

This monopole antenna resonated at 197 MHz when the antenna length was 200 mm, resonated at a frequency of 197 MHz or more when the antenna length was shorter than 200 mm, and resonated at 200 MHz when the antenna length was 195 mm. The average gain of this antenna in the XZ plane was −5.0 dBd.
The real part μr ′ of the complex permeability at 160 MHz to 222 MHz of this composite magnetic body was 3 or more, and the loss tangent tan δμ of the complex permeability was 0.03.

[Example 28]
A monopole antenna of Example 28 was produced in the same manner as in Example 25 except that the coating thickness of the composite magnetic material was changed to 0.8 mm. This monopole antenna resonates at 230 MHz when the antenna length is 200 mm, and needs to be 200 mm or more to resonate at a frequency of 222 MHz or less, and resonates at 200 MHz when the antenna length is 220 mm.

[Example 29]
A monopole antenna of Example 29 was produced in the same manner as in Example 27, except that the coating thickness of the composite magnetic material was 1.7 mm. This monopole antenna resonated at 236 MHz when the antenna length was 200 mm, and resonated at 200 MHz when the antenna length was 230 mm in order to resonate at a frequency of 222 MHz or less.

Next, using the monopole antenna shown in FIG. 16A as a model, a monopole antenna in which the antenna conductor is covered with a composite magnetic material having a real part μr ′ = 3 and tan δμ = 0.02 of the complex magnetic permeability, The relationship between the coating thickness of the composite magnetic material and the minimum antenna length that resonates at 200 MHz was calculated with an electromagnetic field simulator HFSS for the monopole antenna in which the antenna conductor was coated with the composite magnetic material of tan δμ = 0.02. The calculation result is shown by a straight line in FIG. The results of the above examples and reference examples are also plotted in FIG.

As shown in FIG. 27, since the measured values almost coincide with the calculated value line, the antenna conductor length is 200 mm or less due to the composite magnetic material coating of the real part μr ′ = 3 and 6 of the complex permeability. However, it is understood that the coating thickness is required to be 2.4 mm or 1.2 mm or more in order to resonate at a frequency of 200 MHz or less.

DESCRIPTION OF SYMBOLS 1 Base | substrate 2 Coating film 11 Orientation apparatus 12 Application | coating means 13a, 13b Magnet 14 Drying means 21 Orientation apparatus 22a, 22b Magnet 22 Magnet 31 Orientation apparatus 32a, 32b, 33a, 33b, 34a, 34b Magnet 41 Flat magnetic particle 51 Orientation Device 52 Drying means 61 Monopole antenna 62 Antenna conductor 63 Composite magnetic body 64 Ground plate 65 Connection section 66 AC signal transmitter 71 Portable telephone 72 Case 73 Display section 74 Monopole antenna 75 Antenna conductor 76 Composite magnetic body 81 Portable telephone DESCRIPTION OF SYMBOLS 82 Case 83 Display part 84 External antenna terminal 85 Monopole antenna 86 Connection terminal 87 Antenna conductor 88 Composite magnetic body 91 Portable telephone 92 Case 93 Base plate 94 L-shaped antenna 95 Antenna conductor 96 Composite magnetic body 101 Portable telephone 102 Case DESCRIPTION OF SYMBOLS 103 Ground plate 104 Helical antenna 105 Composite magnetic body 106 Antenna conductor H, H1, H2 Magnetic field line g Traveling direction 111 Portable telephone with a protective cover 112 Portable telephone 113 Protection cover 114 Case 115 Display part 116 External antenna terminal 121 Dipole antenna 122 Antenna conductor 123 Composite magnetic body 124 Connection terminal 131 Portable telephone with protective cover 132 Portable telephone 133 Protective cover 134 Case 135 Display unit 136 Terminal for external antenna 141 Spiral antenna 142 Antenna conductor 143 Composite magnetic body 144 Connection terminal 151 Open container 152 Spherical magnetic particles 153 Slurry 154 Dispersion medium 155 Uniaxial rotating body 1511 Sealed container 1620 Monopole antenna 1621 Composite magnetic body 1622 Antenna Body 1624 main plate 1625 AC signal transmitter 1626 connection unit

Claims (32)

1. A composite magnetic material obtained by dispersing tabular magnetic particles in an insulating material,
   The flat magnetic particles have an average thickness of 0.01 μm or more and 0.5 μm or less, an average major axis of 0.05 μm or more and 10 μm or less, and an average aspect ratio (major axis / thickness) of 5 or more. Composite magnetic material.
2. 2. The composite magnetic body according to claim 1, wherein the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is greater than 1, and the loss tangent tan δμ of the complex permeability is 0.1 or less. .
3. 2. The composite magnetic body according to claim 1, wherein the real part μr ′ of the complex permeability in a frequency band from 70 MHz to 500 MHz is larger than 7, and the loss tangent tan δμ of the complex permeability is 0.1 or less. .
4. 2. The composite magnetic body according to claim 1, wherein the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is greater than 10 and the loss tangent tan δμ of the complex permeability is 0.1 or less. .
5. The flat magnetic particles include aluminum (Al), chromium (Cr), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), niobium (Nb), molybdenum (Mo), indium ( 2. The composite magnetic body according to claim 1, which is an iron-nickel alloy containing one or more metal elements selected from the group of In) and tin (Sn).
6. The tabular magnetic particles are formed by deforming and fusing the spherical magnetic particles by applying mechanical stress to the spherical magnetic particles having an average particle diameter of 0.5 μm or less. Item 2. The composite magnetic material according to Item 1.
7. 2. The composite magnetic body according to claim 1, wherein the real part μr ′ of the complex permeability in the frequency band from 90 MHz to 220 MHz is greater than 1, and the loss tangent tan δμ of the complex permeability is 0.05 or less. .
8. 2. The composite magnetic body according to claim 1, wherein the porosity is 20% or less.
9. The real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is 7 or more, the real part εr ′ of the complex permittivity is 15 or more, and (μr ′ · εr ′) ^−1/2 is 0.00. The composite magnetic body according to claim 8, wherein 1 or less and (μr ′ / εr ′) ^1/2 are 0.5 or more and 1 or less.
10. 10. The composite magnetic body according to claim 9, wherein the loss tangent tan δμ of the complex permeability in the frequency band from 70 MHz to 500 MHz is 0.05 or less and the loss tangent tan δε of the complex dielectric constant is 0.1 or less.
11. The composite magnetic body according to claim 1, wherein the insulating material includes a first resin having a cyclic structure in a main chain and having a functional group that is polymerized in a monomer unit.
12. 12. The composite magnetic body according to claim 11, wherein the resin is a thermosetting resin.
13. The composite magnetic body according to claim 11, wherein the resin is an epoxy resin.
14. 12. The composite magnetic body according to claim 11, wherein the resin is a dicyclopentadiene type epoxy resin.
15. The composite magnetic body according to claim 11, wherein an angle formed by the orientation direction of the tabular magnetic particles in the resin and the major axis direction of the tabular magnetic particles is 20 ° or less.
16. The composite magnetic body according to claim 11, wherein the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is 7 or more.
17. The composite magnetic body according to claim 11, further comprising a second resin, which is a resin that imparts flexibility to the first resin.
18. The composite magnetic body according to claim 17, wherein the second resin is an epoxy resin having at least one of a bisphenol A skeleton and a bisphenol F skeleton.
19. 18. The composite magnetic body according to claim 17, wherein the second resin is an epoxy resin containing two or more epoxy groups in one molecule and having an ether skeleton.
20. 18. The composite magnetic body according to claim 17, wherein the second resin is an epoxy resin having any one of a propylene glycol-added bisphenol A skeleton and an ethylene glycol-added bisphenol A skeleton.
21. The composite magnetic body according to claim 17, wherein the real part μr ′ of the complex permeability in the frequency band from 70 MHz to 500 MHz is 7 or more.
22. A method for producing a composite magnetic body according to any one of claims 1 to 21,
    A slurry obtained by dispersing spherical magnetic particles having an average particle size of 0.5 μm or less in a solution containing a surfactant and a dispersion medium are contained in a sealable container, and the total volume of the slurry and the dispersion medium is The slurry is filled so as to have the same volume as in the container, and the slurry is stirred together with the dispersion medium in a sealed state, and the spherical magnetic particles are deformed and fused together to form flat magnetic particles. Process,
    A second step in which the tabular magnetic particles are dispersed and mixed in a solution of an insulating material dissolved in a solvent to form a molding material;
    A molding step of molding or applying the molding material on a substrate to obtain a molded body, and a third step including a drying / curing step of drying / curing the molded body,
    A method for producing a composite magnetic body comprising:
23. The method for producing a composite magnetic body according to claim 22, wherein the insulating material is a resin having a cyclic structure in the main chain and a functional group that is polymerized in monomer units.
24. In the third step, after the molding step, a magnetic field is applied to the obtained molded body to perform an orientation step in which the flat magnetic particles in the molded body are oriented in one direction, and then the drying and curing The method of manufacturing a composite magnetic body according to claim 22, wherein a step is performed.
25. An antenna comprising the composite magnetic body according to any one of claims 1 to 21.
26. A communication apparatus comprising the antenna according to claim 25.
27. A monopole antenna, wherein the antenna conductor is covered with the composite magnetic material according to claim 1.
28. The monopole antenna according to claim 27, wherein the composite magnetic body has a real part μr 'of complex permeability in a frequency band from 160 MHz to 222 MHz being 3 or more.
29. 29. The monopole antenna according to claim 28, wherein a coating thickness of the composite magnetic material is 2.4 mm or more and 10 mm or less.
30. 28. The monopole antenna according to claim 27, wherein the composite magnetic body has a real part μr ′ of complex permeability in a frequency band from 160 MHz to 222 MHz of 6 or more.
31. The monopole antenna according to claim 30, wherein a coating thickness of the composite magnetic body is 1.2 mm or more and 10 mm or less.
32. The monopole antenna according to claim 27, wherein the antenna conductor has a length of 200 mm or less.

Images