JP2000021620A - Compound magnetic substance and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove noises in the ultra high frequency band by composing a compound magnetic substance of a continuous layer made of a magnetic substance and a non-porous diffused layer made of an insulating ceramic or a non-magnetic substance and by specifying the initial permeabilities and permittivities of these layers. SOLUTION: The initial permeabilities of a continuous layer (first layer) consisting of a magnetic substance and a non-porous diffused layer (second layer) consisting of an insulating ceramic or a non-magnetic substance are set in the range of 10-500, and their permittivities at 100 MHz 50 or lower. The method of mixing the magnetic material with the insulating ceramic material or the non-magnetic material, is adjusted so that the second layer is uniformly present in the first layer in a predetermined size. By limiting the size of the second layer to 0.5-200 μm, the second layer has substantially the same size as the grain diameter of the magnetic substance, thereby suppressing internal stresses caused due to distortions of the crystal structure and the like as much as possible and minimizing the deterioration of the permeability, which is a magnetic property. Hence, good impedance characteristics can be obtained for high frequencies.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite magnetic material having a continuous layer made of a magnetic material and a non-porous dispersion layer made of an insulating ceramic or a non-magnetic material.
Although the application is not particularly limited, for example, the present invention relates to a composite magnetic material used for a broadband high frequency noise suppression component for an electronic device, a radio wave absorber, a radio wave absorption sheet, a radio wave shielding sheet, and the like.

[0002]

2. Description of the Related Art In all electronic devices such as power supplies, computers, communication devices, etc., magnetic materials of various materials and shapes are used as noise countermeasures in accordance with an adaptive frequency in order to suppress adverse effects (electromagnetic interference) caused by noise generated from the devices. It is used. Ferrite materials have attracted particular attention because of their variety of shapes, easiness of manufacture, and low cost, and they have been used as noise suppression components for various devices and have demonstrated excellent effects.

[0003] When ferrite is used as an inductor, the impedance (Z) of the inductor increases with frequency. For this reason, in the signal region, the impedance is low and acts as a low-pass filter. As the frequency increases, the impedance becomes dominant in the resistance component (R: resistance) due to an increase in magnetic loss, and the noise (unwanted high-frequency component) is converted into heat. And acts as a noise filter.

[0004] Among ferrite materials, M, which has a high magnetic permeability,
The n-Zn ferrite core is mainly 30 kHz to 30 kHz.
Since it has a high impedance at an adaptive frequency of MHz, it is used in a common mode line filter as a core for suppressing conducted noise at the frequency. Common core shapes include a star-shaped core, a square-shaped core, a toroidal core, an EE core, a UU core, and the like. The core is coated with resin for insulation between the winding and the core. Alternatively, after a bobbin is mounted on a core, the core is wound and used.

Further, among ferrite materials, high-resistance N
i-Zn ferrite cores are mainly 30 MHz to 30 MHz.
Since it has a high impedance at an adaptive frequency of 0 MHz, it is used in the common mode and the normal mode as a radiation noise countermeasure core at the frequency.
Common core shapes include bead core, toroidal core, rectangular core for flat cable (split type),
Examples of the core include a UI type core, and a core is used by directly applying a lead wire or a winding to the core, or attached to an interface cable between devices. In addition, SMDs are used for circuit boards that are small and thin, such as notebook computers and portable devices.
Many types of bead filters have been used as noise suppression components.

On the other hand, in a high-rise building, the building itself becomes a reflector for radio waves, causing a ghost phenomenon of TV. In order to suppress this unnecessary radio wave, Ni-Zn ferrite (some use Mn-Zn ferrite or Mg-Zn ferrite) is mainly used as a radio wave absorber on the wall surface of the high-rise building. . Since this Ni—Zn ferrite has high impedance mainly at an adaptive frequency of 90 MHz to 220 MHz (corresponding to the VHF band), it has good radio wave absorption characteristics at the above-mentioned frequency and has excellent characteristics as a radio wave absorber. I have. In addition, Ni-Zn ferrite is mainly used as a radio wave absorber also on the wall surface of an anechoic chamber used for evaluating and measuring noise.

[0007]

The operating frequency of electronic devices, such as personal computers and portable devices, is increasing at an ever increasing frequency. Along with this, the noise frequency generated from these devices has also been increased to 300 MHz.
There is a need to remove high-frequency noise from z to about 3 GHz (corresponding to the UHF band). However, Ni-Z
Even if an n-type ferrite material is used, it is difficult to remove noise at the above frequency, and a material having a higher frequency (UHF band) and an excellent noise removing effect has been demanded.

In general, the frequency characteristic of the impedance (the frequency at which the impedance exhibits the maximum value: the resonance frequency) shifts to the high frequency side by lowering the magnetic permeability of the ferrite, but the frequency characteristic in the high frequency range from 300 MHz to about 3 GHz (corresponding to the UHF band). In order to obtain a target inductor for noise suppression, the magnetic permeability must be 10 or less. However, when such a material is used as an inductor, the amount of leakage magnetic flux is large and a decrease in impedance cannot be avoided, and the effect as a noise filter is poor. Further, although the inductance increases as the number of windings increases, the stray capacitance of the winding increases, and the frequency characteristic of impedance shifts to a lower frequency side. As a result, a noise removing effect cannot be obtained at a higher frequency. Further, it is possible to increase the impedance by increasing the volume, but this is not practically preferable.

For example, the frequency characteristic of impedance (Z) of a general ferrite material can be expressed as shown in FIG. The impedance increases with frequency, reaches a maximum at some frequency, and then decreases. The impedance can be expressed by the following equation 1 as the sum of the reactance X and the resistance R. Z = jX + R (1)

In order to exhibit the noise removing effect, it is an essential condition that the impedance Z is large. However, the frequency characteristic of the reactance X (depending on the frequency characteristic of the magnetic permeability) and the frequency characteristic of the resistance R (the complex magnetic permeability Is dependent on the frequency characteristics). The guideline of the frequency at which an excellent noise removing effect is exhibited is from a frequency at which resistance R> reactance X to a frequency (resonance frequency) at which impedance Z becomes maximum (reactance X becomes minimum).

The present invention has been proposed in view of the above, and has as its object to provide a composite magnetic material having an effect of removing high-frequency noise from 300 MHz to about 3 GHz (corresponding to the UHF band).

[0012]

SUMMARY OF THE INVENTION The present invention maintains the characteristics of a ferrite material having an excellent noise removing effect,
The purpose is to shift the frequency characteristic of impedance to a higher frequency side while keeping the magnetic permeability as high as possible. In view of the above-mentioned problems of the prior art, the composition and composition of ferrite materials (Ni-Zn-based ferrite, Mg-Zn-based ferrite) are considered. Various mixing methods of insulating ceramic materials and non-magnetic materials (forsterite, steatite, alumina, etc.) were studied. As a result, simply mixing a magnetic material with an insulating ceramic material or a non-magnetic material does not suppress a decrease in magnetic permeability, and a non-porous insulating ceramic or non-magnetic material It has been found that by adopting a structure in which the dispersion layer has a certain size and is evenly interposed, the magnetic permeability is less reduced and the noise removing effect can be maintained even at a high frequency.

The present invention has been made based on the above-mentioned findings, and the gist configuration is as follows. The present invention has a structure having a continuous layer (first layer) made of a magnetic material and a non-porous dispersion layer (second layer) made of an insulating ceramic or a non-magnetic material, and has an initial magnetic permeability of 10 or more. A composite magnetic material having a dielectric constant of not more than 500 and not more than 50 at 100 MHz.

In the present invention, the magnetic material of the first layer is made of Ni—Zn ferrite or Mg—Zn ferrite, and the insulating ceramic or non-magnetic material of the second layer is forsterite, steatite, alumina or the like. It is desirable to consist of at least one of the following. Further, in the composite magnetic material of the present invention, the dispersion layer of the insulating ceramic or the non-magnetic material forming the non-porous second layer is present at a volume ratio of 5 to 55%, and the size of the dispersion layer is It is desirable that the thickness be 0.5 to 200 μm. The composite magnetic material of the present invention preferably has a porosity of 8% or less.

Further, according to the present invention, the magnetic material powder obtained by mixing the main components constituting the magnetic material and then preliminarily firing is mixed with the main component forming the insulating ceramic or the non-magnetic material and then subjected to the heat treatment. The composite magnetic material obtained by mixing and firing is composed of a continuous layer (first layer) made of a magnetic material and a non-porous dispersion layer (second layer) made of an insulating ceramic or a non-magnetic material.
Layer) and the initial magnetic permeability is 10 or more and 5 or more.
A method for manufacturing a composite magnetic material, wherein the dielectric constant at 100 MHz or less and 100 MHz is 50 or less.

In the method of manufacturing a composite magnetic body according to the present invention, the mixing ratio of the insulating ceramic material or the non-magnetic material forming the second layer is 3 to 40 wt%. Is desirably 0.5 to 200 μm. The porosity of the obtained composite magnetic material was 9
It is desirable to set it to 2% or more. Further, in the method for producing a composite magnetic material of the present invention, the magnetic material powder after calcination is processed to have an average particle size of 0.5 to 10 μm, and the heat treatment temperature of the insulating ceramic material or the nonmagnetic material is set to 800.
To 1300 ° C., and the average particle diameter of the powder after the heat treatment is desirably 0.5 to 50 μm.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention maintains the characteristics of a ferrite material excellent in a noise removing effect by examining various compositions of a magnetic material and a method of blending an insulating ceramic or a non-magnetic material. We thought that the frequency characteristics of the impedance could be shifted to the high frequency side while the magnetic susceptibility was as large as possible. As a result, simply mixing the magnetic material powder and the insulating ceramic powder or the non-magnetic material powder does not suppress the decrease in magnetic permeability, and adjusts the method of blending the magnetic material with the insulating ceramic material or the non-magnetic material to adjust the magnetic properties. By uniformly interposing a non-porous dispersion layer made of insulating ceramic or non-magnetic material in a certain size in a continuous layer made of a material, the decrease in magnetic permeability is reduced and the noise removal effect is obtained even at high frequencies. We found that we could maintain. As a result, it has become possible to provide a composite magnetic material having an effect of removing high-frequency noise from 300 MHz to about 3 GHz (corresponding to the UHF band).

In the present invention, the composition of the magnetic material, the insulating ceramic material or the non-magnetic material, the mixing ratio of the insulating ceramic material powder or the non-magnetic material powder, the average particle diameter, the heat treatment temperature, the dispersion layer in the composite magnetic material, The reasons for limiting the volume ratio, its size, and the porosity of the composite magnetic body to the above ranges are as follows.

The composition of the magnetic material includes Ni-Zn based ferrite and Mg-Zn
A system ferrite is desirable. If the sintering temperature of the insulating ceramic material or non-magnetic material to be mixed is lower than the sintering temperature of the magnetic material, the insulating ceramic or non-magnetic material is melted and a uniform dispersion layer cannot be obtained. The composition of the ceramic or non-magnetic material is a material that sinters at the same temperature or higher than the firing temperature of the magnetic material (a material that has the same melting point as or higher than the magnetic material)
And forsterite, steatite and alumina are particularly desirable.

In order to minimize the melting of the insulating ceramic material or the non-magnetic material into the magnetic material, it is preferable to heat-treat the insulating ceramic material or the non-magnetic material before mixing the powder with the magnetic material powder. . The heat treatment temperature varies depending on the firing temperature of the composite magnetic material and the type of the insulating ceramic material or the non-magnetic material.
When the temperature is about 1300 ° C., a target composite magnetic material can be obtained without impairing magnetic properties.

When the mixing ratio of the insulating ceramic material or the non-magnetic material added to the magnetic material is less than 3 wt%, there is no significant difference from the characteristics of the magnetic material alone, and no effect of improving the characteristics at a high frequency is observed. On the other hand, if the mixing ratio of the insulating ceramic material or the non-magnetic material exceeds 40% by weight, the magnetic permeability is reduced, which is not practical. For this reason, the mixing ratio of the insulating ceramic is preferably 3 to 40 wt%, more preferably 5 to 35 wt%.

If the volume ratio of the insulating ceramic or nonmagnetic dispersion layer constituting the second layer is less than 5%, there is no significant difference from the characteristics of the magnetic material alone, and no effect of improving the characteristics at high frequencies can be seen. On the other hand, if the volume ratio of the dispersion layer exceeds 55%, the magnetic permeability decreases, and the practicability is lacking. Therefore, the volume ratio of the dispersion layer is preferably 5 to 55%, and more preferably 9 to 50%.

The reason that the size of the insulating ceramic or nonmagnetic dispersion layer constituting the second layer is limited to 0.5 to 200 μm is that the size of the insulating ceramic dispersion layer is 0.5 to 200 μm. In this case, the crystal grain size becomes substantially the same as the crystal grain size of the magnetic material, and it becomes possible to minimize internal stress caused by distortion of the crystal structure and the like, and as a result, deterioration of magnetic characteristics (magnetic permeability) is minimized. This is because it was considered that the frequency characteristics of the impedance could be shifted to the high frequency side while keeping the impedance. More preferably, it is 1 to 150 μm.

If the porosity of the composite magnetic material exceeds 8%, it absorbs water and causes instability of magnetic properties and adverse effects on peripheral components, which is not preferable in practical use. Therefore, the porosity is desirably 8% or less.

In order to minimize the decrease in the magnetic permeability of the composite magnetic material, in order to obtain a structure in which the magnetic material has a continuous layer and the insulating ceramic or non-magnetic material has a non-porous uniform dispersion layer, The average particle size of the insulating ceramic material powder or the nonmagnetic material powder is preferably equal to or slightly larger than the average particle size of the magnetic material powder. Thereby, the reaction with the magnetic material can be suppressed as much as possible, and a more uniform dispersion layer can be formed. The average particle size of the magnetic material powder is
In consideration of handling properties such as dispersibility, granulation properties, moldability, etc., it is desirable that the average particle size of the insulating ceramic material powder or the non-magnetic material powder mixed with this magnetic material powder is about 0.5 μm to 10 μm. 0.5 slightly larger
About 50 μm is desirable, and more preferably, 1 to 20 μm.
m.

[0026]

EXAMPLE 1 48 mol% of Fe ₂ O ₃ , NiO 19 as a magnetic material
Using Ni-Zn ferrite having a composition of mol%, ZnO 27 mol%, and CuO 6 mol%, the respective raw materials were weighed and mixed so as to have the above-mentioned composition, and were calcined at 850 ° C.
Thereafter, a magnetic material powder pulverized by a vibration mill was produced. The average particle size of the magnetic material powder was 2 μm. Forsterite powder (heat treatment temperature 800 ° C., average particle size 5 after pulverization) was added to this magnetic material powder as an insulating ceramic material.
μm), mixed with the magnetic material powder at various mixing ratios, added a binder, and granulated. The granules were formed into a cylindrical shape having an outer diameter of 8.5 mm, an inner diameter of 1.85 mm, and a height of 7 mm. It was compression-molded into a shape (shape 1) and a cylindrical shape (shape 2) having an outer diameter of 9 mm and a height of 6 mm, and was fired at 1200 ° C.

The magnetic permeability (μi) and impedance (Z) of these samples (X: reactance, R: simultaneous evaluation of resistance) were evaluated using shape 1, and the permittivity (ε) and porosity were obtained using shape 2. An evaluation was performed. The permeability, impedance, and permittivity are measured by an impedance analyzer (Yokogawa,
Evaluation was carried out by a coaxial measurement method using Hewlett-Packard Co., Ltd. 4191A). In the measurement of the dielectric constant, a sample in which electrodes were applied to upper and lower surfaces of a sample was used. Table 1 shows the results. In Table 1, those within the scope of the present invention are examples, and those outside the scope are comparative examples. As a comparative example, characteristics of a Ni—Zn ferrite having a magnetic permeability of 10 were also described (Comparative Example 5). FIG. 2 shows the frequency characteristics of impedance of Comparative Example 1, Comparative Example 5, and Example 5.

As can be seen from FIG. 2, the frequency characteristic of the impedance of the embodiment of the present invention is higher than that of the comparative example 1 having the magnetic permeability of 600, and is excellent in the high frequency characteristic. Further, as compared with Comparative Example 5 having a magnetic permeability of 10 from FIG.
It can be seen that the frequency band exhibiting the noise absorption characteristics is also wide. That is, the composite magnetic material of the present invention can increase the frequency characteristics of impedance and broaden the noise absorption characteristics while minimizing the decrease in magnetic permeability, and can increase the noise absorption characteristics from 300 MHz to 3 GHz. It can be seen that the composite magnetic material was excellent.

[0029]

[Table 1]

Example 2 48 mol% of Fe ₂ O ₃ and NiO 19 as a magnetic material
Using Ni-Zn ferrite having a composition of mol%, ZnO 27 mol%, and CuO 6 mol%, the respective raw materials were weighed and mixed so as to have the above-mentioned composition, and were calcined at 850 ° C.
Thereafter, a magnetic material powder pulverized by a vibration mill was produced. The average particle size of the magnetic material powder was 2 μm. Forsterite powder was used as the insulating ceramic material powder for the magnetic material powder, and the mixed powder produced during the production process of forsterite and the pulverized powder obtained by variously changing the heat treatment temperature and the pulverization treatment conditions after mixing were mixed with the magnetic material. The powder was mixed at a mixing ratio of 25 wt%. Thereafter, after adding a binder, the mixture is granulated, and the granules have an outer diameter of 8.5 mm and an inner diameter of 1.
85mm, height 7mm cylindrical (shape 1) and outer diameter 9m
m, compression molded into a column (shape 2) with a height of 6 mm
It was baked at 00 ° C. The magnetic permeability of these samples (μi)
The impedance (Z) (X: reactance, R: resistance was evaluated simultaneously) was evaluated using shape 1, and the dielectric constant (ε) and porosity were evaluated using shape 2. The magnetic permeability, impedance, and permittivity were evaluated by a coaxial measurement method using an impedance analyzer (such as 4191A manufactured by Yokogawa Hewlett-Packard Co., Ltd.). Also, for dielectric constant measurement,
The electrode was applied to the upper and lower surfaces of the sample. When the dielectric constant (100 MHz) of each sample was evaluated, values of 12 to 13 were shown irrespective of the comparative examples and examples. The surface of each sample was checked for the layer structure and the size of the dispersion layer (the distribution of the longest diameter) was measured using a scanning electron microscope (SEM) and an energy dispersive X-ray analyzer (EDX). The observation region is within a rectangle whose length is about 10 times the crystal grain size of the magnetic material on one side.
The longest diameter distribution of each dispersion layer contained therein was evaluated. Table 2 shows the results. FIG. 3 shows the results of analyzing the sample surfaces of Example 5 and Comparative Example 6 using SEM and EDX. In Table 2, those within the scope of the present invention are examples, and those outside the scope are comparative examples.

[0031]

[Table 2]

As shown in Table 2 and FIG. 3, regarding the forsterite powder to be added to the magnetic material, the form of the formed composite magnetic material (magnetic material) differs depending on the processing method of the powder generated in the process of manufacturing forsterite. I understand. That is,
When the mixed powder produced during the process of manufacturing forsterite is added to the magnetic material powder, the magnetic material powder and the forsterite powder (actually, MgO and SiO2) react during firing, so that solid solution or particles It is considered that the target composite magnetic material was not obtained because of precipitation in the magnetic field and a sharp decrease in magnetic permeability and impedance.

On the other hand, when the heat-treated powder generated in the process of manufacturing forsterite is added to the magnetic material powder, if the heat treatment temperature is from 800 ° C. to 1300 ° C., the forsterite is uniformly dispersed in the magnetic material after firing. It was confirmed that they were dispersed. The size of each of the forsterite dispersed layers varies depending on the heat treatment temperature and the pulverization conditions (average particle size) after the heat treatment.
It was an elliptical layer of about 00 μm. It was also confirmed that each dispersion layer was an aggregate of forsterite crystals and had a non-porous structure. Here, the porous body (porous) means that a large number of pores (voids) independently exist between crystal grains as disclosed in FIGS. 1 and 2 of JP-B-1-23884. The dispersion layer of the present invention does not have such a porous structure (expressed as non-porous in the present specification). Thus, it is considered that the deterioration of the magnetic properties of the magnetic material can be suppressed as much as possible, and the intended composite magnetic body can be obtained.

Further, from Table 2, regarding the heat treatment temperature of forsterite and the average particle diameter adjusted by pulverization after heat treatment, the heat treatment temperature of forsterite was 800 ° C. to 13 ° C.
At 00 ° C., if the average particle size exceeds 50 μm, the porosity becomes larger than 8% and water was absorbed, so that the sample was taken as a comparative example.

As described above, the composite magnetic material according to the present invention achieves a higher frequency characteristic of impedance and a wider frequency band exhibiting the effect of noise absorption characteristics, and has a higher noise at higher frequencies than conventional materials. It is expected to show absorption properties. This is very suitable for a ferrite core such as a noise filter or a ferrite plate such as a radio wave absorber.
Excellent magnetic material parts can be obtained in the frequency band from 0 MHz to 3 GHz.

[0036]

According to the present invention, a composite magnetic material having excellent noise absorption characteristics in a frequency band of 300 MHz to 3 GHz can be obtained as compared with the conventional Ni-Zn ferrite. Further, the composite magnetic material of the present invention is extremely effective as a noise filter, a radio wave absorber, and a radio wave absorption sheet.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing a relationship between impedance (Z), reactance (X), resistance (R) and frequency according to the present invention.

FIG. 2 is a diagram illustrating frequency characteristics of impedance of Example 5 and Comparative Examples 1 and 5 according to the present invention.

FIG. 3 is a schematic diagram of a sintered body surface structure of Example 5 and Comparative Example 6 according to the present invention.

Claims (17)

[Claims] 1. A structure having a continuous layer (first layer) made of a magnetic material and a non-porous dispersion layer (second layer) made of an insulating ceramic, and having an initial magnetic permeability of 10 or more and 500 or less. A composite magnetic material having a dielectric constant at 100 MHz of 50 or less. 2. A structure having a continuous layer (first layer) made of a magnetic material and a non-porous dispersion layer (second layer) made of a non-magnetic material, and having an initial permeability of 10 to 500, 100
A composite magnetic material having a dielectric constant of 50 or less at MHz. 3. The magnetic material forming the first layer is Ni-Z.
2. The composite magnetic body according to claim 1, wherein said insulating ceramic is made of n-based ferrite or Mg-Zn-based ferrite, and said insulating ceramic forming said second layer is made of at least one of forsterite, steatite and alumina. 4. The volume ratio of the dispersion layer of the second layer is 5-5.
The composite magnetic material according to any one of claims 1 to 3, wherein the content is 5%. 5. The dispersion layer of the second layer has a size of 0.5 to 0.5.
The composite magnetic body according to claim 1, wherein the composite magnetic body has a thickness of 200 μm. 6. The composite magnetic body according to claim 1, wherein the porosity is 8% or less. 7. A mixture of a magnetic material powder obtained by preliminarily sintering after mixing a main component constituting a magnetic body and an insulating ceramic material powder obtained by mixing and heating a main component constituting an insulating ceramic. A composite magnetic material obtained by firing,
The composite magnetic material has a structure having a continuous layer (first layer) made of a magnetic material and a nonporous dispersion layer (second layer) made of insulating ceramic, and has an initial magnetic permeability of 10 or more and 500 or less. , A dielectric constant at 100 MHz is 50 or less. 8. Mixing and firing of a magnetic material powder obtained by mixing the main components of the magnetic material and pre-baking, and a non-magnetic material powder obtained by mixing the main components of the non-magnetic material and then heat-treating the mixture. Wherein the composite magnetic material has a structure having a continuous layer (first layer) made of a magnetic material and a non-porous dispersion layer (second layer) made of a non-magnetic material. A method for producing a composite magnetic material, comprising: an initial magnetic permeability of 10 to 500, and a dielectric constant at 100 MHz of 50 or less. 9. The magnetic material forming the first layer is Ni-Z.
8. The composite magnetic body according to claim 7, wherein said insulating ceramic is made of n-based ferrite or Mg-Zn-based ferrite, and said insulating ceramic forming said second layer is made of at least one of forsterite, steatite and alumina. Production method. 10. The mixing ratio of an insulating ceramic material or a non-magnetic material for forming the second layer is 3 to 40 wt%.
The method for producing a composite magnetic material according to any one of claims 7 to 9, wherein 11. The dispersion layer (second layer) having a size of 0.5.
The thickness is 5 to 200 μm.
The method for producing a composite magnetic material according to any one of the above. 12. The method according to claim 7, wherein the porosity of the composite magnetic body is 8% or less. 13. The magnetic material powder forming the first layer has an average particle size of 0.5 to 10 μm, and the insulating ceramic material powder or the nonmagnetic material powder forming the second layer has an average particle size of 0.5 to 10 μm. The method for producing a composite magnetic material according to any one of claims 7 to 12, wherein the thickness is 0.5 to 50 m. 14. The heat treatment temperature of the insulating ceramic material powder or the non-magnetic material powder forming the second layer is 80.
The temperature is from 0 ° C. to 1300 ° C.
3. The method for producing a composite magnetic material according to any one of 3. 15. A noise filter component using the composite magnetic material according to claim 1. 16. A radio wave absorber using the composite magnetic material according to claim 1. 17. A radio wave absorbing sheet and a radio wave shielding sheet using the composite magnetic material according to claim 1.