JP2008263098A - Compound magnetic body, circuit substrate using the same, and electronic equipment using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite magnetic body for suppressing the deterioration of relative permeability in a high frequency, and for increasing a wavelength shortening rate when applying it to an electronic component and an antenna or the like. <P>SOLUTION: The magnetic powder of compound magnetic body whose plastic deformation is easily carried out by a mechanical stress is acquired by doping metallic elements. In mixing the magnetic powder with distributed media, flatting is carried out by the shearing stress of the mechanical stress of distributed media, and plastic deformation is carried out in a crystal direction by the mechanical stress, and flat magnetic powder with a small thickness and a large aspect rate is acquired. The anti-magnetic field of the flat magnetic powder thus acquired is small so that it is possible to suppress the deterioration of relative permeability. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a high-frequency circuit board and a high-frequency electronic component, and more particularly to a composite magnetic body suitable as a material for the high-frequency circuit board and the high-frequency electronic component and a method for manufacturing the same.

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 and circuit boards mounted on electronic devices. In general, the wavelength λg of the electromagnetic wave propagating in the material is determined by the wavelength λ0 of the electromagnetic wave propagating in the vacuum, the real part εr ′ of the complex permittivity (hereinafter referred to as relative permittivity εr), and the real part μr of the complex permeability. '(Hereinafter referred to as relative permeability μr)
λg = λ0 / (εr · μr) ^1/2
Therefore, it is known that the larger the relative dielectric constant εr and the relative magnetic permeability μr, the larger the wavelength shortening rate and the smaller electronic components and circuit boards.

However, eddy currents are generated on the surface of magnetic materials in the high-frequency band used by information and communication equipment, and this eddy current generates a magnetic field in a direction that cancels the change in the applied magnetic field, resulting in a decrease in the apparent permeability of the material. Was invited. Moreover, since an increase in eddy current causes energy loss due to Joule heat, it has been difficult to use it as a material for circuit boards and electronic components. To reduce eddy currents,
d = 1 / (π · f · μ0 · μr · σ) ^1/2
It is effective to make the diameter of the magnetic powder smaller than the skin depth d expressed by Here, f is the signal frequency, σ is the conductivity of the magnetic powder, and μ 0 is the permeability of the vacuum. In recent years, with the advancement of nanotechnology, the miniaturization of magnetic particles has progressed, and some cases have been reported in which the decrease in the relative permeability μr of materials at high frequencies is suppressed.

  For example, in Patent Document 1, the present inventors appropriately mix and disperse spherical magnetic powder or flat magnetic powder in a resin using rotation and revolution mixing using a dispersion medium, so that the relative permeability at 500 MHz to 1 GHz is achieved. A composite magnetic material having a magnetic susceptibility μr greater than 1 and a loss tangent tan δ of 0.1 or less is provided.

Japanese Patent Application No. 2007-12092

  In Patent Document 1, the present inventors have found that loss can be reduced even in a frequency band of 500 MHz to 1 GHz by suitably performing dispersion of magnetic powder. However, 78-permalloy (78Ni-22Fe alloy) forming a composite magnetic body has a small plastic deformation ability, so the influence of the demagnetizing field cannot be removed sufficiently, and the crystal orientation is small, so the high-frequency magnetic field and the easy axis of magnetization coincide. It was difficult to make it difficult to increase the magnetic permeability.

  The present invention has been made in view of the above problems, and is easily plasticized with respect to a specific crystal direction (here, the easy axis of magnetization) when a metal element is added to alloy particles and mechanical stress is applied. In a composite magnetic body composed of a deformable magnetic powder and an insulating material, the major axis direction of the flat magnetic powder coincides with the direction of the easy axis of magnetization, and the relative magnetic permeability μr is at a frequency of 1.2 GHz or less. It is an object of the present invention to provide a composite magnetic body characterized by being larger than 10 and having a loss tangent tan δ of 0.3 or less, and an electronic device using the same.

  As a result of intensive studies, the present inventors have found that the magnetic permeability can be further improved in a frequency band of 1.2 GHz or less by suitably performing the dispersion and orientation of the flat magnetic powder. .

  That is, according to the first aspect of the present invention, in the composite magnetic body constituted by dispersing magnetic powder in an insulating material, the relative permeability μr at a frequency of 1.2 GHz or less is greater than 10, and A composite magnetic body having a loss tangent tan δ of 0.3 or less is obtained.

  According to the second aspect of the present invention, there is obtained the composite magnetic body according to the first aspect, wherein the composite magnetic body has a relative dielectric constant εr of 10 or more at a frequency of 1 GHz or less.

  According to a third aspect of the present invention, there is obtained the composite magnetic body according to the first aspect, wherein the composite magnetic body has a relative dielectric constant εr of 10 or less at a frequency of 1 GHz or less.

  According to the fourth aspect of the present invention, the magnetic powder is made of aluminum (Al), chromium (Cr), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), niobium (Nb). ), Molybdenum (Mo), indium (In), and tin (Sn) are permalloy (Fe—Ni alloy) to which one or more metal elements are added. The described composite magnetic material is obtained.

  According to a fifth aspect of the present invention, there is obtained the composite magnetic body according to the fourth aspect, wherein the concentration of the metal element added to the magnetic powder is 0.1 wt% to 90 wt%. It is done.

  According to a sixth aspect of the present invention, in the composite magnetic body according to the fourth or fifth aspect, the magnetic powder is easily plastically deformed in the direction of the easy magnetization axis when mechanical stress is applied. Is obtained.

  According to a seventh aspect of the present invention, the magnetic powder has a flat shape, a thickness of 0.01 to 1 μm, a length of 0.02 to 10 μm, and an aspect ratio (length / thickness). The composite magnetic body according to any one of the first to sixth aspects is obtained, wherein is 2 or more.

  According to an eighth aspect of the present invention, the flat magnetic powder is obtained by mechanically deforming a spherical magnetic powder into a flat shape in the step of mixing the magnetic powder in a dispersion solvent. The composite magnetic body according to the seventh aspect is obtained.

According to a ninth aspect of the present invention, the insulating material includes polyimide resin, polybenzoxazole resin, polyphenylene resin, polybenzocyclobutene resin, polyarylene ether resin, polysiloxane resin, epoxy resin, polyester resin, fluorine Synthetic resin or liquid phase resin including at least one of resin, polyolefin resin, polycycloolefin resin, cyanate resin, polyphenylene ether resin, and polystyrene resin, or Al ₂ O ₃ , SiO ₂ , TiO ₂ , 2MgO · SiO _2. The composite magnetic body according to any one of the first to eighth aspects, which is a raw material for at least one ceramic selected from the group consisting of ceramics of MgTiO ₃ , CaTiO ₃ , SrTiO ₃ , and BaTiO _3. Got That.

  According to a tenth aspect of the present invention, in the composite magnetic body according to any one of the first to eighth aspects, the flat magnetic powder is oriented in a certain direction in the insulating material. Is obtained.

  According to an eleventh aspect of the present invention, in the first to ninth aspects, a specific crystal plane of the crystal constituting the flat magnetic powder is oriented in a certain direction of the flat magnetic powder. A composite magnetic material according to any one of the above is obtained.

  According to the twelfth aspect of the present invention, there is obtained a composite magnetic body characterized in that the major axis direction of the flat magnetic powder coincides with the easy magnetization axis.

  According to a thirteenth aspect of the present invention, there is obtained a circuit board including at least the composite magnetic material according to any one of the first to twelfth aspects.

  According to the fourteenth aspect of the present invention, there is obtained an electronic component comprising at least the composite magnetic body according to any one of the first to twelfth aspects.

  According to a fifteenth aspect of the present invention, an electronic component comprising at least the composite magnetic body according to any one of the first to twelfth aspects is obtained.

  According to the present invention, when a metal element is added to an alloy particle and a mechanical stress is applied, the magnetic powder and the insulating material that are easily plastically deformed with respect to a specific crystal direction (for example, an easy magnetization axis direction). In the constructed composite magnetic body, the length direction of the flat magnetic powder coincides with the direction of the easy axis of magnetization, the relative permeability μr is greater than 10 at a frequency of 1.2 GHz or less, and the loss tangent tan δ. Can be provided, and a composite magnetic body and an electronic device using the same can be provided. By applying the composite magnetic material having a high magnetic permeability according to the present invention as a material for circuit boards and / or electronic components, further downsizing and low power consumption of information communication devices in the band of several hundred MHz to 1 GHz are realized. It becomes possible to do.

  First, the magnetic powder constituting the composite magnetic body according to the embodiment of the present invention will be described.

  As the material of the magnetic powder, permalloy (Fe-Ni alloy), supermalloy (Fe-Ni-Mo alloy), sendust (Fe-Si-Al alloy), Fe-Si alloy, Fe-Co alloy, Fe-Cr Alloy, Fe-Cr-Si alloy, etc., aluminum (Al), chromium (Cr), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), niobium (Nb), molybdenum (Mo) It is preferable to add a metal element such as indium (In) or tin (Sn).

  The addition amount of the metal element is preferably in the range of 0.1 wt% or more and 90 wt% or less. The reason is that if the addition amount of the metal element is less than 0.1 wt%, the soft magnetic powder cannot obtain a sufficient plastic deformability, while the addition amount is 90 wt% because the magnetic moment of the metal element itself is small. This is because the saturation magnetization of the magnetic powder is reduced when the value exceeds.

  A preferred shape of the magnetic powder will be described. The magnitude of the demagnetizing field in the magnetic powder depends on the shape of the powder. For example, in the case of a spherical shape, since a demagnetizing field is isotropic, it is difficult to obtain excellent magnetic characteristics in a high frequency region. On the other hand, when the powder has a flat shape, the demagnetizing field in the direction parallel to the flat surface is remarkably reduced, and the obtained magnetic permeability is increased.

  In the step of mixing the magnetic powder in the dispersion solvent, the flat magnetic powder in the present invention applies mechanical stress by the action of the added metal element when the spherical magnetic powder is flattened by the shear stress of the dispersion medium. And a specific crystal direction (here, easy magnetization axis direction) that is easily plastically deformed and preferably has a thickness of 0.01 to 1 μm. When the thickness of the flat magnetic powder is less than 0.01 μm, it is difficult to manufacture and handling becomes difficult. Further, if the thickness of the flat magnetic powder exceeds 1 μm, it is not preferable because an eddy current is generated and magnetic characteristics at high frequencies are lowered. Further, if the aspect ratio (length / thickness) of the flat magnetic powder is smaller than 2, the demagnetizing field of the powder is increased and the relative magnetic permeability μr of the composite magnetic material is decreased, which is not preferable.

  Next, the insulating material constituting the composite magnetic body will be described.

  When the composite magnetic material is used as a material for a circuit board, it is preferable that the dielectric constant is low from the viewpoint of increasing the characteristic impedance. As the insulating material, polyimide resin, polybenzoxazole resin, polyphenylene resin, polybenzocyclobutene Low dielectric constant synthetic resins such as resins, polyarylene ether resins, polysiloxane resins, epoxy resins, polyester resins, fluororesins, polyolefin resins, polycycloolefin resins, cyanate resins, polyphenylene ether resins, polystyrene resins are suitably selected. The

On the other hand, when a high dielectric constant such as a capacitor or an antenna element is required, ceramics such as Al ₂ O ₃ , SiO ₂ , TiO ₂ , 2MgO · SiO ₂ , MgTiO ₃ , CaTiO ₃ , SrTiO ₃ , BaTiO ₃ , or the like A mixture of these inorganic and organic materials can be used as appropriate.

  The manufacturing process of the composite magnetic body according to the present invention includes a process of manufacturing a dispersion solvent in which a surfactant is added to a solvent during a process of manufacturing a slurry by dispersing and mixing magnetic powder in a solvent, A mixing step of mixing the magnetic powder with the magnetic powder, and when the magnetic powder is mixed in the dispersion solvent, the dispersion medium and the insulating material are added. Mix.

  During the above-described mixing step, the flat magnetic powder is produced by plastically deforming the magnetic powder to which the metal element is added in a specific crystal plane direction by the mechanical stress of the dispersion medium.

  Examples of the apparatus that can be used in the above mixing process of mixing the solvent, surfactant, magnetic powder, dispersion medium, and insulating material include a kneader, a roll mill, a pin mill, a sand mill, a ball mill, and a planetary ball mill. In order to use the dispersion medium according to the present invention, a sand mill, a ball mill, a planetary ball mill or the like is suitable.

  Dispersion media include metals or metal oxides such as aluminum, steel and lead, oxide sintered bodies such as alumina, zirconia, silicon dioxide and titania, nitride sintered bodies such as silicon nitride, silicon carbide And glass such as sintered silicide, soda glass, lead glass, and high specific gravity glass.

  Next, a method for applying the obtained slurry will be described. As a coating method, a dry film can be produced by forming this into an arbitrary sheet shape by a known forming method such as a press method, a doctor blade method, or an injection molding method. Among these methods, it is desirable to form a laminated body of composite magnetic bodies into a sheet by a doctor blade method. The slurry is applied after volatilization of the solvent and concentration to adjust the viscosity suitable for the above application method.

  The slurry applied in the form of a sheet by the above method is preferably dried while applying a DC external magnetic field. By applying a DC external magnetic field during drying, the flat particles are oriented in a direction parallel to the sheet surface. At this time, since the easy magnetization axis in the flat particles is oriented in the major axis direction of the flat powder, the shape anisotropy and the crystal anisotropy are simultaneously oriented.

  Finally, the dry film thus obtained is heat-treated and press-molded in a reducing atmosphere or vacuum to obtain a composite magnetic body.

  The greatest feature of the present invention is that the flat magnetic powder constituting the composite magnetic body is easily plastically deformed with respect to a specific crystal direction (here, the easy magnetization axis direction), and is easily applied with mechanical stress. It is plastically deformed, has a high aspect ratio, and is arranged (orientated) parallel to a specific direction by applying external magnetization when producing a composite magnetic body, so the demagnetizing coefficient in the plane direction of the composite magnetic body is low. In addition, the magnetic permeability of the composite magnetic material can be increased by matching the length direction of the flat magnetic powder with the easy axis of magnetization crystal.

  Next, examples according to the present invention will be described.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely by Example 1 and 2, this invention is not limited by these Examples.

  2 g of permalloy magnetic powder with an average particle size of 0.25 μm added with a metal element is mixed with 10 g of xylene and cyclopentanone 4: 1 mixed solution in a dispersion containing a nitrogen-containing graft polymer as a surfactant and further dispersed. Zirconia beads having an average particle diameter of 200 μm were added as a medium, and planetary stirring was carried out for 50 minutes in this state to flatten the magnetic powder. 0.5 g of a resin varnish obtained by diluting the polycycloolefin resin to a solid content ratio of 40% was added to the slurry thus obtained, and further mixed for 5 minutes by planetary stirring. The revolution speed during planetary stirring was 2000 rpm, and the rotation speed was 800 rpm.

Next, the obtained mixed liquid is allowed to stand to settle the dispersion medium (the specific gravity of the magnetic powder is 7 to 8 and the specific gravity of zirconia is 6 to 7, but the particle diameter of the zirconia beads is magnetic with respect to 200 μm. Since the particle size of the powder is 0.25 μm, the zirconia beads are heavier, so the zirconia beads are settled). After the solvent was evaporated and formed into a film by the doctor blade method, it was dried at room temperature while orienting the magnetic particles by applying a magnetic field of 1.6 × 10 ⁵ A / m. Six dry films obtained in this way were laminated and press fired with a reduced pressure press. The press conditions were raised to 130 ° C. for 20 minutes under normal pressure, then held at pressure of 2 MPa and held for 5 minutes, then heated to 160 ° C. and held for 40 minutes to cure the resin to a thickness of 350 μm. A composite magnetic material was prepared.

  The obtained magnetic powder in the composite magnetic material is finally flattened in the direction of the easy magnetization axis of the crystal and has a form in which crystal planes parallel to the easy magnetization axis are stacked in the thickness direction.

  When the complex magnetic permeability of this composite magnetic material was measured by the parallel line method, the relative magnetic permeability μr = 11 and the magnetic loss tan δ = 0.25 at 1.2 GHz (see FIG. 1), and the dielectric constant was measured by the parallel plate method. When measured, the relative dielectric constant was 12, and the dielectric loss tan δ was 0.05.

  A structural photograph of this composite magnetic material is shown in FIG. It can be seen that the magnetic particles are flattened and oriented in a certain direction. The average size of the flat particles at this time was about 0.03 μm in thickness and about 1 μm in length, and the aspect ratio was about 33. Furthermore, it can be seen from the X-ray diffraction results shown in FIG. 3 that a specific crystal plane is oriented. For comparison, the magnetic permeability characteristics, cross-sectional photographs, and X-ray diffraction results of a composite magnetic material produced by a conventional method without applying a DC magnetic field are shown in FIGS. 4, 5, and 6, respectively. They are not arranged in a certain direction, and no orientation is observed on the crystal plane. As a result, it can be seen that a relative permeability of only about 7 can be obtained.

  As an example of applying this composite magnetic body to an electronic component, an example of a monopole antenna using the composite magnetic body is shown. As shown in FIG. 7, the antenna element has a structure in which two composite magnetic bodies 10 having a length of 50 mm, a width of 5 mm, and a thickness of 0.5 mm are used and a strip conductor 12 having a length of 55 mm and a width of 1.5 mm is sandwiched between the antenna elements. It was. The antenna element was connected to the center of a 300 mm square conductor ground plate 14, and the connection point was the feeding point 16, and 50Ω was fed.

  FIG. 8 shows the input reflection characteristics of the antenna. The actual measurement results and the calculated values obtained by inputting the material constants of the composite magnetic body into the electromagnetic field simulator HFSS are in good agreement. Further, when the resonance frequency of the antenna loaded with the composite magnetic body (denoted as WithMD in FIG. 8) and the antenna not loaded (denoted as WithoutMD in FIG. 8) are compared, the resonance frequency is increased by loading the composite magnetic body 10. The shift is from 1.26 GHz to 0.88 GHz. In other words, a significant wavelength shortening effect is obtained due to the effects of the relative magnetic permeability and relative permittivity of the composite magnetic material, and this antenna can be reduced by about 30%.

  The present invention is applied to a semiconductor device, a circuit element, a flat panel display, and other high frequency electronic components, and is also applied to a high frequency circuit board on which these are mounted, thereby enabling miniaturization and low power consumption. Accordingly, it is possible to reduce the size and power consumption of all the high-frequency electronic devices on which the electronic components and / or circuit boards to which the present invention is applied are mounted. Furthermore, the composite magnetic body according to the present invention can be applied to an antenna to reduce the size of the antenna.

It is a figure which shows the value of the magnetic characteristic of the composite magnetic body obtained in Example 1 of this invention with respect to a frequency. It is a scanning electron micrograph of the composite magnetic body obtained in Example 1 of the present invention. It is a figure which shows the X-ray-diffraction result of the composite magnetic body obtained in Example 1 of this invention. It is a figure which shows the value of the magnetic characteristic of the composite magnetic body obtained by the conventional method with respect to a frequency. It is a scanning electron micrograph of the composite magnetic body obtained by the conventional method. It is a figure which shows the X-ray-diffraction result of the composite magnetic body obtained by the conventional method. It is the schematic which shows the structure of the antenna in one Example of this invention. It is a figure which shows the input reflection characteristic of an antenna with respect to a frequency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Composite magnetic body 12 Strip conductor 14 Conductor ground plate 16 Feeding point

Claims (16)

  In a composite magnetic body constituted by dispersing magnetic powder in an insulating material, the real part μr ′ of the complex permeability at a frequency of 1.2 GHz or less is larger than 10 and the loss tangent tan δ is 0.3 or less. A composite magnetic material characterized by being.   2. The composite magnetic body according to claim 1, wherein a real part εr ′ of a complex dielectric constant at a frequency of 1 GHz or less is 10 or more.   2. The composite magnetic body according to claim 1, wherein a real part εr ′ of a complex dielectric constant at a frequency of 1 GHz or less is 10 or less.   The magnetic powder is made of aluminum (Al), chromium (Cr), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), niobium (Nb), molybdenum (Mo), indium (In). The composite magnetic body according to claim 1, wherein the composite magnetic body is a permalloy (Fe—Ni alloy) to which at least one metal element of tin (Sn) is added.   The composite magnetic body according to claim 4, wherein the concentration of the metal element added to the magnetic powder is 0.1 wt% to 90 wt%.   6. The composite magnetic body according to claim 4, wherein the magnetic powder is easily plastically deformed with respect to the easy axis direction when mechanical stress is applied.   The magnetic powder has a flat shape, a thickness of 0.01 to 1 μm, a length of 0.02 to 10 μm, and an aspect ratio (length / thickness) of 2 or more. Item 7. The composite magnetic material according to any one of Items 1 to 6.   8. The composite magnetic body according to claim 7, wherein the flat magnetic powder is obtained by mechanically deforming a spherical magnetic powder into a flat shape in the step of mixing the magnetic powder in a dispersion solvent. The insulating material is polyimide resin, polybenzoxazole resin, polyphenylene resin, polybenzocyclobutene resin, polyarylene ether resin, polysiloxane resin, epoxy resin, polyester resin, fluorine resin, polyolefin resin, polycycloolefin resin, cyanate Synthetic resin or liquid phase resin including at least one of resin, polyphenylene ether resin, and polystyrene resin, or Al ₂ O ₃ , SiO ₂ , TiO ₂ , 2MgO · SiO ₂ , MgTiO ₃ , CaTiO ₃ , SrTiO ₃ , 9. The raw material of at least one ceramic selected from the group consisting of ceramics of BaTiO ₃ , 3Al ₂ O ₃ .2SiO ₂ , ZrO ₂ , SiC, and AlN. The composite magnetic body described.   The composite magnetic body according to claim 1, wherein the flat magnetic powder is oriented in a certain direction in the insulating material.   The composite magnetic body according to any one of claims 1 to 10, wherein a specific crystal plane of a crystal constituting the flat magnetic powder is oriented in a certain direction of the flat magnetic powder.   The composite magnetic body according to claim 1, wherein a major axis direction of the flat magnetic powder coincides with an easy magnetization axis.   A composite magnetic material characterized in that the long axis direction of the flat magnetic powder coincides with the easy magnetization axis.   A circuit board comprising at least the composite magnetic body according to claim 1.   An electronic component comprising at least the composite magnetic body according to claim 1.   An electronic apparatus comprising at least the composite magnetic body according to claim 1.

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