JPH05251225A - High-frequency soft magnetic material - Google Patents

Abstract

PURPOSE:To provide a soft magnetic material, which does not require to perform a sintering and moreover, is superior in high-frequency characteristics. CONSTITUTION:A mixed powder of a chemical compositional ratio of NiO:CuO: ZnO:Fe2O3=15:6:31:48 is fired to obtain spinel type ferrite powder of a particle diameter of longer than 10nm and shorter than 7mum. For example, a resin is mixed in this spinel type ferrite powder to mold the mixture into a prescribed molded material and the molded material is formed into a molded article. This molded article is superior in high-frequency characteristics and if the particle diameter of the spinel type ferrite powder is longer than 10nm and shorter than 7mum, the molded article, which is superior in high-frequency characteristics, can be obtained by merely molding, in short, without going through a sintering process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic material used in a high frequency band.

[0002]

2. Description of the Related Art Generally, this kind of soft magnetic material is required to have a high magnetic permeability (μ) even in a high frequency band. Therefore, a spinel type ferrite material having a relatively high electric resistance value is required. It is used. This spinel type ferrite material is hard and brittle in nature, so that it is difficult to process. For this reason, a powder metallurgy method is used in which ferrite powder or raw material powder is molded into a desired shape and then the molded body is sintered to form a sintered body.

[0003]

However, in order to obtain the above-mentioned sintered body, it is necessary to sinter the molded body at a high temperature of 1000 ° C to 1400 ° C. The sintering shrinkage causes deformation of the sintered body, and as a result, it is necessary to process the sintered body to obtain a desired shape.

The above-mentioned sintering at a high temperature has a problem that not only enormous energy is consumed but also the sintering equipment becomes expensive. Further, it is generally difficult to process the sintered body, which not only increases the processing cost but also leads to material loss.

Further, when used in a high frequency band, in consideration of efficiency, it is desirable to sinter the spinel ferrite material into a small shape, but processing into a small shape is extremely difficult in terms of processing accuracy. There is a problem that it is difficult. On the other hand, such a ferrite material (inductor element) and a dielectric material (capacitance element) may be integrally sintered to form an LC element. In such an LC element, a joint surface between the materials is joined. In the above, there is a region where the characteristics deteriorate due to the diffusion of atoms during sintering.

In any case, including the sintering process causes various problems as described above.

An object of the present invention is to provide a soft magnetic material which does not require sintering and has excellent high frequency characteristics.

[0008]

According to the present invention, there is obtained a high-frequency soft magnetic material characterized by being a soft magnetic spinel type ferrite powder having a particle diameter of 10 nm or more and 7 μm or less.

[0009]

In the present invention, as the high frequency soft magnetic material, soft magnetic spinel type ferrite powder having a particle size of 10 nm or more and 7 μm or less is used. Such soft magnetic spinel ferrite powder can obtain excellent magnetic properties simply by forming it into a desired shape into a formed body. When the particle size of the soft magnetic spinel type ferrite exceeds 7 μm,
As a magnetic material, the loss (for example, the loss coefficient δ _{10MHz at 10MHz} ) increases. On the other hand, when the particle size of the soft magnetic spinel type ferrite is less than 10 nm, the ferrite powder particles exhibit paramagnetic behavior and the soft magnetism decreases.

[0010]

EXAMPLES The present invention will be described below with reference to examples.

Example 1 Nickel oxide (Ni oxide having a particle size of 0.5 μm or less)
O), cupric oxide (CuO), zinc oxide (ZnO), and iron oxide (α-Fe ₂ O ₃ ) are prepared, and these powders are wet mixed using a ball mill to have a chemical composition ratio of 15 NiO.
A raw material mixed powder of 6 CuO.31ZnO.48Fe ₂ O ₃ was obtained.

Next, the raw material mixed powder was fired at a temperature in the range of 750 ° C. to 1200 ° C. by rapid heating and rapid cooling in the atmosphere to obtain a fired powder. Then, the calcined powder was crushed using a ball mill and the particle size was 0.5 μm, 1.0 μm, and 3.
0 μm, 5.0 μm, 7.0 μm, 10.0 μm, 15.0 μm, 2
Nine kinds of spinel type ferrite powders of 0.0 μm and 25.0 μm or less were obtained in total.

Then, 30 volume percent (vol.%) Of epoxy resin was mixed with each spinel type ferrite powder to form a mixture, and the space factor of the spinel type ferrite powder was about 62 vol. Outside diameter of this mixture so that
It was molded into a molded body having a diameter of 10 mm, an inner diameter of 2 mm and a height of 10 mm. Then, the temperature of each molded body thus obtained was adjusted to 14
After holding at 0 ° C. for 2 hours, it was used as a measurement sample.

Next, using a YHP impedance analyzer and a coaxial measuring jig, the μ frequency characteristics and loss coefficient of these measurement samples were measured. The measurement result is shown in FIG.

As shown in FIG. 1, it can be seen that among these measurement samples, the frequency characteristic is deteriorated in the sample having the maximum particle size exceeding 15 μm. In other words, the maximum particle size is 15μ
It can be seen that in the measurement sample of m or less, the decrease of μ starts at about 500 MHz. On the other hand, the loss coefficient at a frequency of 10 MHz (tan δ _{10 MHz} ) shows a remarkably low value in the sample having the maximum particle size of 7 μm or less, and it can be seen that it is almost zero. Note that μ of these samples at 10 MHz
Was about 10.

As is clear from the above description, Ni-Z
If the maximum particle size in the n-type spinel ferrite powder is set to 7 μm or less, high frequency characteristics can be improved by simply molding.

Example 2 Manganese oxide (MnO), zinc oxide (ZnO), and iron oxide (α-Fe ₂ O ₃ ) were prepared and the chemical composition ratio was 28MnO.18ZnO.54Fe ₂ O using the coprecipitation method. ₃ raw material powders were created. Observation of the particle size of this raw material powder revealed that
The particles were 30 nm.

Next, this raw material powder is treated at a temperature of 700 ° C. to 1250.
Calcinated in the range of ℃ to obtain a calcinated powder, and crushed using a ball mill to obtain a particle size of 0.5 μm and 1.
0 μm, 3.0 μm, 5.0 μm, 7.0 μm, 10.0 μm, 1
Nine kinds of spinel type ferrite powders of 5.0 μm, 20.0 μm and 25.0 μm in total were obtained.

Then, for each of these 9 types of spinel type ferrite powder, 20 vol. % Polyamide resin to form a mixture, which is then heat-molded,
The space factor of spinel type ferrite powder is about 60 vol. %, The outer diameter was 10 mm, the inner diameter was 2 mm, and the height was about 10 mm.

The measurement frequency characteristics and loss coefficient of these measurement samples were measured using the same apparatus as in Example 1. The result is shown in FIG.

As shown in FIG. 2, it can be seen that among these measurement samples, the frequency characteristics are deteriorated in the sample having the maximum particle size exceeding 15 μm. In other words, the maximum particle size is 15μ
It can be seen that in the measurement sample of m or less, the decrease of μ starts at about 500 MHz. On the other hand, the loss coefficient at a frequency of 10 MHz (tan δ _{10 MHz} ) shows a remarkably low value in the sample having the maximum particle size of 7 μm or less, and it can be seen that it is almost zero. Note that μ of these samples at 10 MHz
Was about 10.

As is clear from the above description, Mn-Z
If the maximum particle size in the n-type spinel ferrite powder is 7 μm or less, high frequency characteristics can be improved.

Example 3 Magnesium carbonate (MgCO ₃ ), trimanganese tetraoxide (Mn ₃ O ₄ ), lithium carbonate (Li ₂ CO ₃ ), nickel oxide (NiO), zinc oxide (ZnO), cupric oxide ( CuO) and iron oxide (α-Fe ₂ O ₃ ) are prepared,
The chemical composition ratio is 15MgO ・ 20MnO ・ 15ZnO ・
_{50Fe 2 O 3, 7 Li 2} O · 33ZnO · 60Fe 2 O 3,
20NiO ・ 33ZnO ・ 47Fe ₂ O ₃ , 25CuO ・ 25Zn
A raw material of O.50Fe ₂ O ₃ was prepared. Then, these raw material powders were fired in the same manner as in Example 1 to produce spinel-type ferrite powders each having a particle size of about 7 μm or less. Then, about 30 vol. Of polyimide resin was added to each of these spinel ferrite powders. % Of the mixture to form a mixture, the mixture was compression-molded to obtain a measurement sample. The measurement result is shown in FIG.

As is clear from FIG. 3, it is understood that the μ frequency characteristics and the loss coefficient are good in each measurement sample. That is, if the maximum particle size in various spinel ferrite powders is 7 μm or less, high frequency characteristics can be improved.

As is apparent from the above-mentioned examples, the particle size (maximum particle size) of the soft magnetic spinel type ferrite powder is 7
If it is less than μm, it is not necessary to sinter at high temperature, that is,
High-frequency characteristics can be improved by simply forming a molded body.

If the particle size of the soft magnetic spinel type ferrite powder is less than 10 nm, the ferrite powder particles exhibit paramagnetic behavior, and the soft magnetism deteriorates. Therefore, the particle diameter of the soft magnetic spinel ferrite powder needs to be 10 nm or more.

In the above embodiment, the chemical composition ratio is 15
NiO ・ 6 CuO ・ 31ZnO ・ 48Fe ₂ O ₃ , 28MnO
・ 18ZnO ・ 54Fe ₂ O ₃ , 15MgO ・ 20MnO ・ 15Z
nO ・ 50Fe ₂ O ₃ , 7 Li ₂ O ・ 33ZnO ・ 60Fe ₂
O ₃ , 20NiO ・ 33ZnO ・ 47Fe ₂ O ₃ , 25CuO ・
The spinel-type ferrite powder of 25ZnO.50Fe ₂ O ₃ has been described, but the present invention is not limited to the spinel-type ferrite powders having these composition systems and composition values. The present invention can be applied to. That is, if the maximum particle size is 7 μm or less
When the thickness is 10 nm or more, similar high frequency characteristics can be obtained with other soft magnetic spinel ferrite powders.

Further, in the above-mentioned embodiments, the raw material powder or the coprecipitated ferrite powder was fired in the air or the nitrogen atmosphere when the powder was manufactured, but the hydrothermal synthesis method, the spray roasting method, etc. may be used. It may be used, and in any case, it may be one that improves the diffusion and dispersibility of atoms. The firing atmosphere may be oxidizing or reducing, and the product may be soft magnetic spinel ferrite.

In addition, in the above examples, epoxy resin, polyamide resin, and polyimide resin were mentioned as the resin mixed with the ferrite powder, but these resins maintain the shape of the powder compact, disperse the powder, and It is used for insulation. Therefore, the resin mixed with the ferrite powder may be either a thermosetting resin or a thermoplastic resin, and is appropriately selected according to the required properties. For example, as the resin mixed with the ferrite powder, phenol-based, silicon-based, holester-based, fluorine-based, polypropylene-based, vinyl chloride-based, phthalate-based, polyurethane-based, polyethylene-based, natural rubber, and synthetic rubber can be used. ..

Further, in the above-mentioned embodiment, when the resin is mixed with the fired powder and the mixture is molded, the compression molding by the press is used. Can be injection molding, extrusion molding, roll-rolling molding, or the like, and in any case, any method can be used as long as it is a method for obtaining a powder compact.

[0031]

As described above, according to the present invention, the soft magnetic spinel ferrite powder has a particle diameter of 10 nm.
Since the thickness is 7 μm or more, good magnetic characteristics can be obtained by simply molding the soft magnetic spinel ferrite powder. Therefore, unlike the conventional case, a sintering process is not required, and as a result, there is no shrinkage deformation due to sintering, and processing after sintering is unnecessary. Further, even when composited with different kinds of materials, since sintering is not performed, there is no diffusion at the boundary surface and the characteristics do not deteriorate. In addition, since sintering is unnecessary, not only energy saving can be achieved but also equipment cost can be reduced.

[Brief description of drawings]

Fig. 1 Chemical composition ratio is 15NiO ・ 6CuO ・ 31ZnO ・
48Fe is a diagram showing the relationship between the maximum particle diameter of the magnetic core properties and powder in the magnetic material using the spinel-type ferrite powder is a ₂ O _3.

[2] Chemical composition ratio 28MnO · 18ZnO · 54Fe ₂ O
FIG. 3 is a diagram showing the relationship between the magnetic core characteristics and the maximum particle size of the powder in the magnetic material using the spinel ferrite powder of No. ₃ .

FIG. 3 is a diagram showing magnetic core characteristics of magnetic materials using spinel type ferrite powders having various chemical composition ratios.

Claims (1)

[Claims] 1. A high-frequency soft magnetic material, which is a soft magnetic spinel type ferrite powder having a particle diameter of 10 nm or more and 7 μm or less.