JP2020202325A - Thermally-cured body of metal magnetic composite material - Google Patents

Abstract

To provide a thermally-cured body of a metal magnetic composite material, which is low in the volume occupancy of pores and higher in strength.SOLUTION: The problem is solved by a thermally-cured body of a metal magnetic composite material comprising: a thermosetting resin; metal magnetic powder to which a metal magnetic material is reduced; and non-magnetic inorganic powder to which a non-magnetic inorganic material is reduced. In the thermally-cured body, a volume occupancy of the thermosetting resin to a total volume of the thermally-cured body is 11.0 vol.% or larger, and a volume occupancy of pores to the total volume of the thermally-cured body is 10.0 vol.% or smaller. The percentage of a volume of the non-magnetic inorganic powder to a volume of the thermosetting resin is 5.0 vol.% or larger and smaller than 200.0 vol.%. An average particle diameter (D50) of the non-magnetic inorganic powder is equal to or smaller than 1/10 of an average particle diameter (D50) of the metal magnetic powder.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thermosetting body of a metal magnetic composite material, a method for producing the same, and the like.

Various forms of coil parts used in electronic devices and the like are known, but a magnetic core material composed of a metal magnetic composite material in which a metal magnetic powder is dispersed in a binder resin and a coil or a coil assembly are integrally molded. Many coil parts are used. For example, Patent Document 1 describes an inductance component (coil component) in which a winding coil is enclosed in a powder magnetic body composed of an admixture containing a soft magnetic powder and a binder and is pressure-molded. Further, Patent Document 2 includes a magnetic powder and a binder resin, and further includes a core containing pores having a volume occupancy of 8% by volume or more with respect to the total product, and a coil embedded in the core. The element (coil component) is described.

Such coil components are required to have high superimposition characteristics and low direct current resistance (DCR). Therefore, the magnetic core material in the coil component is required to increase the volume occupancy of the contained metal magnetic powder. This is because the relative magnetic permeability is increased, the number of turns required for the coil to obtain the same L value (inductance) is reduced, and a low DCR can be obtained.

On the other hand, such coil parts are also required to pass the MSL test (Moisture Sensitivity Level Test (moisture absorption resistance level test)). That is, it is required that there is no characteristic change (inductance change rate, etc.) or appearance abnormality (cracking, breakage, etc.) when the coil parts are absorbed in a high temperature and high humidity environment and then passed through a reflow furnace (MSL). Level 1). This MSL test is a test for confirming that when the moisture absorbed inside the coil component evaporates and vaporizes in a high temperature and high humidity environment, the component is not adversely affected.

Japanese Unexamined Patent Publication No. 2006-31920 Japanese Unexamined Patent Publication No. 2016-171115

Here, the magnetic core material composed of the cured body (molded body) of the metal magnetic composite material contains a certain amount of air. Therefore, there are many air gaps (vacancy) in the coil component provided with such a magnetic core material, and the pores allow water vapor to pass through. In the coil parts containing many such vacancies, for the MSL test, when the moisture absorbed inside evaporates and vaporizes in the reflow furnace, the water vapor is instantly released from the vacancies to the outside. , The internal pressure does not increase easily, and the coil parts are not easily damaged.
However, coil parts with many holes easily absorb the humidity of the environment, and as a result, rust may occur inside.

Therefore, by lowering the volume occupancy of the pores in the magnetic core material in the coil component, rust is less likely to occur inside, and the volume occupancy of the metal magnetic powder can be increased thereby, so that the coil. Although it is possible to improve the characteristics of the parts, in the MSL test, the internal pressure of coil parts with a low volume occupancy of such pores increases due to vaporized water vapor, and the internal pressure cannot be withstood, causing cracks and microcracks. It ends up.
Therefore, in the conventional coil component, in order to pass the MSL test, there is a problem that the volume occupancy of the pores in the magnetic core material composed of the cured body of the metal magnetic composite material cannot be reduced.

The present invention has been made in view of the above problems, and is composed of a thermosetting body of a metal magnetic composite material having a low volume occupancy of pores and higher strength, and a thermosetting body of the metal magnetic composite material. It is an object of the present invention to provide coil parts and the like including a magnetic core material.

In order to solve the above problems, the present inventor has diligently studied the volume occupancy of the thermosetting resin and the volume occupancy of the pores in the thermosetting body of the metal magnetic composite material, and the non-magnetic inorganic powder and the thermosetting resin. By keeping the ratio of the volume of the metal magnetic powder and the ratio of the average particle diameter (D ₅₀ ) of the metal magnetic powder and the non-magnetic inorganic powder within a predetermined range, the strength of the thermosetting body of the metal magnetic composite material can be further improved. As a result, it was found that a magnetic core material or a coil component having a low volume occupancy of pores and capable of clearing the MSL test could be obtained, and the present invention was completed.

That is, the present invention is a thermosetting body of a metal magnetic composite material containing a thermosetting resin, a metal magnetic powder obtained by powdering a metal magnetic material, and a non-magnetic inorganic powder obtained by powdering a non-magnetic inorganic material. Therefore, the volume occupancy of the thermosetting resin with respect to the total volume of the thermosetting body is 11.0 vol% or more, and the volume occupancy of the pores with respect to the total volume of the thermosetting body is 10.0 vol% or less. The ratio of the volume of the non-magnetic inorganic powder to the volume of the thermosetting resin is 5.0 vol% or more and less than 200.0 vol%, and the average particle size (D ₅₀ ) of the non-magnetic inorganic powder is the average particle of the metal magnetic powder. It is a thermosetting body of a metal magnetic composite material having a diameter (D ₅₀ ) or less of 1/10 or less.

Further, one aspect of the present invention is a coil component including a coil and a magnetic core material, wherein at least a part of the magnetic core material is composed of a thermosetting body of the metal magnetic composite material. is there.

Further, in the present invention, the ratio of the volume to the volume of the thermosetting resin having a volume occupancy ratio of 12.1 vol% or more with respect to the total volume of the material, the metal magnetic powder obtained by pulverizing the metal magnetic material, and the thermosetting resin. nonmagnetic but that and an average particle size of less than 5.0 vol% or more 200.0vol% _{(D 50)} was powdered and non-magnetic inorganic material is 1/10 or less of the average particle diameter of the metal magnetic powder _{(D 50)} A material preparation step of mixing an inorganic powder and a solvent to obtain a metal magnetic composite material, and compression molding of this metal magnetic composite material until the volume occupancy of pores with respect to the total volume is 10.0 vol% or less. Production of a thermosetting body of a metal magnetic composite material, comprising a compression molding step of obtaining a molded body of the metal magnetic composite material and a thermosetting step of thermosetting the molded body to obtain a thermosetting body of the metal magnetic composite material. It also includes methods.

According to the present invention, it is composed of a thermosetting body of a metal magnetic composite material having a low volume occupancy rate of pores and a higher strength and capable of withstanding an MSL test, and a thermosetting body of the metal magnetic composite material. A coil component including a magnetic core material can be provided.

It is a figure (cross-sectional view) which shows an example of the manufacturing process of the coil part which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described.
First, an embodiment of a thermosetting body of a metal magnetic composite material according to the present invention will be described in detail.

The thermosetting body of the metal magnetic composite material according to the present embodiment contains at least a thermosetting resin, a metal magnetic powder, and a non-magnetic inorganic powder. In addition, the embodiment containing a material other than the above (for example, a dispersant, a plasticizer, an organometallic soap, etc.) is not excluded as long as the effect of the present invention is not affected.
Hereinafter, each material will be described in detail.

<Thermosetting resin>
First, the thermosetting resin will be described.
The thermosetting resin in the present embodiment is a reactive resin composition containing a prepolymer having a functional group as a main component (content rate of 90 wt% or more), and is softened and flowed by heating to gradually form a three-dimensional network structure. It is a resin composition that undergoes a cross-linking reaction to be formed and is cured. The thermosetting resin is not particularly limited as long as it plays a role as a binder resin and is cured by heating. For example, a thermosetting type epoxy resin (bisphenol type, naphthalene type, etc.), Examples thereof include silicon-based resins (methylphenylsilicon resins, etc.), phenol-based resins (novolac type, resol-type, etc.), polyamide-based resins, polyimide-based resins, polyphenylene sulfide-based resins, and the like. In particular, it is preferably any one of an epoxy resin, a silicon resin and a phenol resin, and more preferably an epoxy resin from the viewpoint of heat resistance and the like. The same effect can be obtained by using any type of epoxy resin. Further, the thermosetting resin may be a solid powder, a granulated resin, or a liquid resin.

In preparing the metal magnetic composite material, a solvent may be mixed with the thermosetting resin in order to prepare the thermosetting resin as a resin solution. This solvent is removed by drying or the like in a manufacturing process or the like, but it is preferable that the amount of the solvent used is small in order to easily reduce the volume occupancy of the pores in the heat-cured material described later (for example). , The ratio of the volume of the solvent to the total volume of the material used for the metal magnetic composite material excluding the solvent is less than 5.0 vol%, further 0.5 vol% or more and 2.0 vol% or less, etc.). The solvent is preferably one that can be removed by drying or the like in the material preparation step of the metal magnetic composite material, the subsequent compression molding step, the heat curing step, etc., and alcohol, toluene, chloroform, methyl ethyl ketone, acetone, ethyl acetate, etc. The organic solvent of is shown as a preferred example.

<Metallic magnetic powder>
Next, the metallic magnetic powder will be described.
The metallic magnetic powder in the present embodiment is a powder of a metallic magnetic material and is not particularly limited as long as it is a magnetic powder containing iron as a main component. Those to which chromium (Cr), silicon (Si), nickel (Ni), aluminum (Al), cobalt (Co), carbon (C) and the like are added can be used. Further, amorphous metal powder or pure iron powder may be used. Specifically, Fe-Ni system (Permalloy), Fe-Si system (silicon steel), Fe-Al system, Fe-Co system (Permenzur), Fe-Si-Cr system, Fe-Al-Cr system. , Fe-Si-Al-based (sendust) and other alloy powders, non-crystalline metal powders such as amorphous metals, crystalline iron powders such as carbonyl iron powder, and the like.

The content of iron, which is the main component of the metallic magnetic powder, is preferably 90 wt% or more, more preferably 92 wt% or more. Further, it is preferably 98 wt% or less, and more preferably 97 wt% or less.
It is preferable that this metallic magnetic powder contains at least one of the above-mentioned subcomponents, and the balance is iron and unavoidable impurities.

The Cr content of this metallic magnetic powder is preferably 2 wt% or more and 10 wt% or less, and more preferably 3 wt% or more and 8 wt% or less.
Cr combines with oxygen in the atmosphere to easily form chemically stable oxides (eg, Cr ₂ O _3, etc.). Therefore, the thermosetting body of the metal magnetic composite material containing Cr has particularly excellent corrosion resistance. Further, since the Cr oxide has a large specific resistance, the Cr oxide layer is formed near the surface of the particles made of the metal magnetic composite material, so that the particles can be more reliably insulated from each other.
Therefore, by setting the Cr content within the above range, a metal-magnetic composite material having excellent corrosion resistance and capable of manufacturing coil parts and the like having a smaller eddy current loss can be obtained.

For the same reason, the Ni content of this metallic magnetic powder is preferably 2 wt% or more and 10 wt% or less, and more preferably 3 wt% or more and 8 wt% or less. Similarly, the Al content of this metallic magnetic powder is preferably 2 wt% or more and 10 wt% or less, and more preferably 3 wt% or more and 8 wt% or less.

Further, this metallic magnetic powder preferably has a Si content of 2 wt% or more and 10 wt% or less, and more preferably 3 wt% or more and 8 wt% or less.
Si is a component that can increase the magnetic permeability of coil parts obtained by using a metallic magnetic composite material. Further, when the metallic magnetic powder contains Si, the specific resistance becomes high, so that it is also a component capable of suppressing the interparticle eddy current loss. Therefore, by setting the Si content within the above range, a metal magnetic composite material capable of manufacturing a coil component or the like having a smaller eddy current loss while increasing the magnetic permeability can be obtained.

Further, in addition to the main component and sub-component as described above, this metallic magnetic powder has B (boron), Ti (titanium), V (vanadium), Mn (manganese) as components having a smaller content than this sub-component. ), Cu (copper), Ga (gallium), Ge (germanium), Zr (zirconium), Nb (niobium), Mo (molybdenum), Ru (ruthenium), Rh (lodium), Ta (tantal), etc. It may contain at least one species. In that case, the total content of these components is preferably 1 wt% or less.
Further, this metallic magnetic powder may contain components such as P (phosphorus) and S (sulfur) that are inevitably mixed in during the manufacturing process. In that case, the total content of these components is preferably 1 wt% or less.

The average particle size (D ₅₀ ) of this metallic magnetic powder is preferably 5 μm or more and 30 μm or less, more preferably 7 μm or more and 25 μm or less, and further preferably 8 μm or more and 20 μm or less. Further, the particle shape is preferably spherical (substantially spherical).
Here, in the present invention, the "average particle size (D ₅₀ )" is an integrated value of 50% in the volume-based particle size distribution obtained by using a particle size distribution measuring device by a laser diffraction / scattering method (microtrack method). It means the particle diameter (median diameter). When the particles are agglomerated, it means the particle size of the agglomerates. The same applies to the average particle size (D ₅₀ ) of the non-magnetic inorganic powder described later. As a specific measuring device for the average particle size (D ₅₀ ), a laser diffraction / scattering type particle size distribution measuring device (particle size distribution) LA-960 (manufactured by HORIBA, Ltd.) can be mentioned.

Further, as this metallic magnetic powder, it is preferable to use one produced by a water atomizing method or a gas atomizing method.
Here, the "water atomizing method" is a method of producing a metal powder by colliding the molten metal (molten metal) with water (atomized water) jetted at high speed to pulverize and cool the molten metal. is there. The surface of the metallic magnetic powder produced by this water atomization method is oxidized during the production process, and an oxide layer containing iron oxide is naturally formed.
The "gas atomizing method" is a method in which a jet stream such as an inert gas or air is blown from the surroundings onto the flow of the molten metal to pulverize the flow of the molten metal and ossify it into a metal powder.
Since the metal magnetic powder produced by this water atomization method or the gas atomization method has a shape close to a sphere, the filling rate is adjusted when a thermosetting body or a coil part is manufactured using the obtained metal magnetic composite material. Can be enhanced. As a result, a product having a higher density and a higher magnetic flux density can be obtained.

In order to suppress the eddy current loss in the particles, the metallic magnetic powder may be an insulated metal magnetic powder whose surface is subjected to an insulating treatment such as an insulating coating. As the insulating coat, a powder coating such as a silica coat or an alumina coat can be preferably used.

<Non-magnetic inorganic powder>
Next, the non-magnetic inorganic powder will be described.
The non-magnetic inorganic powder in the present embodiment is a powder of a non-magnetic, that is, an inorganic material having a relative magnetic permeability close to 1 (including 1). For example, silica powder, calcium carbonate powder, alumina (aluminum oxide) powder, barium titanate powder and the like can be used as non-magnetic inorganic powder, and it is preferable to use these spherical (substantially spherical) particle powders, and spherical silica powder. It is particularly preferable to use (spherical silica particles).
The surface of the non-magnetic inorganic powder may be hydrophobized in order to facilitate mixing with the thermosetting resin. As a result, the non-magnetic inorganic powder is likely to be uniformly dispersed in the thermosetting resin, and as a result, the strength of the obtained thermosetting body can be further increased. Examples of the hydrophobizing treatment include coating with silicone oil and substitution treatment (coupling treatment) of surface functional groups (for example, hydroxyl groups) with hydrophobic groups using a silane coupling agent or the like.

Then, in order to obtain a thermosetting body of a metal magnetic composite material having higher strength, the average particle size (D ₅₀ ) of this non-magnetic inorganic powder is 1 / of the average particle size (D ₅₀ ) of the metal magnetic powder. It needs to be 10 or less (10% or less), preferably 8.0% or less, more preferably 6.0% or less, and even more preferably 5.0% or less. Further, the lower limit thereof is preferably 0.1% or more, and more preferably 0.4% or more.
The specific average particle size (D ₅₀ ) of this non-magnetic inorganic powder varies depending on the average particle size (D ₅₀ ) of the metal magnetic powder used in combination, and therefore cannot be unequivocally determined. For example, 0.01 μm or more and 3.0 μm. Hereinafter, 0.05 μm or more and 2.0 μm or less, further 0.1 μm or more and 1.0 μm or less, and the like are shown.
Further, the non-magnetic inorganic powder is preferably a group of particles that are not substantially aggregated. Here, in the present invention, the "substantially non-aggregated particle group" means that the ratio of the aggregated particles among the particles constituting the particle group is 0.1 wt% or less.

When spherical silica powder is used as the non-magnetic inorganic powder, it is preferable to use spherical silica powder prepared by a sol-gel method or a melting method. Since such spherical silica powder does not easily aggregate particles when blended with a metal magnetic composite material (primary particles tend to become independent), the strength of the thermosetting body and the MSL test resistance of the obtained metal magnetic composite material become higher. This is because it will be excellent.
Here, the "sol-gel method", which is a method for preparing spherical silica powder, is a method of obtaining a silica porous body (silica gel) by polycondensation of a metal alkoxide, drying and powdering the silica, and is a "melting method". Is a method of melting natural minerals and synthetic silica at a high temperature such as a flame to obtain highly pure spherical silica powder.

<Thermosetting body of metal magnetic composite material>
Next, the thermosetting body of the metal magnetic composite material according to the present embodiment, in which the metal magnetic composite material containing the above-mentioned thermosetting resin, metal magnetic powder and non-magnetic inorganic powder is compression-molded and thermo-cured, will be described.

In the thermosetting body of the metal magnetic composite material according to the present embodiment, the volume occupancy of the thermosetting resin with respect to the total volume is 11.0 vol% or more, and the volume occupancy of the pores formed by the residual air or the like is It must be 10.0 vol% or less.
The volume occupancy of this thermosetting resin is preferably 12.0 vol% or more, more preferably 13.0 vol% or more and 35.0% or less, and 15.0 vol% or more and 33.0%. The following is more preferable. Further, the volume occupancy of the pores is preferably less than 8.0 vol%, more preferably 6.0 vol% or less, and further preferably 5.0 vol% or less.
The heat-cured body of the metal magnetic composite material according to the present embodiment reduces the volume occupancy of the pores in this way, and as a result, increases the volume occupancy of the metal magnetic powder in the total volume of the heat-cured body. For example, the volume occupancy of this metallic magnetic powder can be more than 50.0 vol%, further 55.0 vol% or more, and further 60.0 vol% or more. Then, by using such a thermosetting body as a magnetic core material, a coil component having a high relative magnetic permeability can be obtained.

Here, in the metal magnetic composite material before compression molding and thermosetting, the volume of the thermosetting resin in the total volume of the materials used for the metal magnetic composite material excluding the components (solvent etc.) removed by drying and the like and air. The occupancy rate may be in a range such that the volume occupancy rate with respect to the total volume of the thermosetting body after compression molding and thermosetting is 11.0 vol% or more, but for example, 12.1 vol% or more, preferably 13.0 vol. Can be%.

Further, in the thermosetting body of the metal magnetic composite material according to the present embodiment, the volume occupancy of the thermosetting resin described above is within the above range, and a predetermined average particle diameter (D) with respect to the volume of the thermosetting resin. ₅₀ ) The volume ratio of the non-magnetic inorganic powder (volume ratio when the volume of the thermosetting resin is the denominator and the volume of the non-magnetic inorganic powder is the molecule) is 5.0 vol% or more and less than 200.0 vol%. There is a need.
The volume ratio is preferably 10.0 vol% or more and 180.0 vol% or less, more preferably 15.0 vol% or more and 100.0 vol% or less, and 20.0 vol% or more and 80.0 vol% or less. Is more preferable.
The thermosetting body of the metal magnetic composite material according to the present embodiment has a volume occupancy of the thermosetting resin and a volume of the thermosetting resin and a non-magnetic inorganic powder having a predetermined average particle size (D ₅₀ ). By setting the ratio within the above range, the strength is further increased, and a thermosetting body having a strength capable of withstanding the MSL test can be obtained even if the volume occupancy of the pores is low.

<Coil parts>
Next, an embodiment of a coil component including a magnetic core material including a thermosetting body of a metal magnetic composite material according to the present invention will be described in detail.
The coil component in the present embodiment includes a coil and a magnetic core material which is at least partially composed of the above-mentioned thermosetting metal magnetic composite material.

Here, the coil is formed by winding a wire such as a round wire or a flat wire, and the shape, number of wires, number of turns (number of turns), and the like of the wire are not particularly limited. Further, the surface of this wire may be insulated and coated.
Further, the magnetic core material is a magnetic core of the coil (inner core material provided in the core portion of the coil) and a magnetic outer body (outer core material in which the coil is embedded) that embeds the coil. In the coil component according to the present embodiment, at least a part of the magnetic core material, for example, either or both of the magnetic core and the magnetic exterior body, is composed of the heat-cured body of the above-mentioned metal magnetic composite material. The coil component according to the present embodiment includes a magnetic outer body that embeds the coil as a magnetic core material, and at least this magnetic outer body is composed of the thermosetting body of the above-mentioned metal magnetic composite material. This is preferable from the viewpoint of suppressing the generation of rust inside the coil parts. However, it may be a coil component that does not include a magnetic exterior body and includes a coil and a magnetic core composed of a thermosetting body of the above-mentioned metal magnetic composite material. Alternatively, all the magnetic core materials (magnetic core and magnetic outer body) provided in the coil component may be composed of the thermosetting body of the above-mentioned metal magnetic composite material.

Such coil components according to the present embodiment can have high superimposition characteristics and low DC resistance, and can have a coil (including a choke coil), an inductor, a noise filter, a reactor, a motor, a generator, a transformer, and an antenna. It is preferably used as such.

<Manufacturing method of thermosetting body of metal magnetic composite material>
Next, a method for producing a thermosetting body of the metal magnetic composite material according to the present embodiment will be described.
The method for producing a thermosetting body of the metal magnetic composite material according to the present embodiment (for example, a non-embedded type magnetic core material in which a coil is not embedded therein) is not particularly limited, but the following preferred embodiments Will be explained.

The method for producing a thermosetting body of a metal magnetic composite material according to the present embodiment includes at least a material preparation step, a compression molding step, and a thermosetting step. These steps can be performed, for example, as follows.

[Material preparation process]
The above-mentioned thermosetting resin, metallic magnetic powder, and non-magnetic inorganic powder having an average particle diameter (D ₅₀ ) of 1/10 or less of the average particle diameter (D ₅₀ ) of the metallic magnetic powder are prepared. Next, the metallic magnetic powder and the non-magnetic inorganic powder are mixed and dispersed in a thermosetting resin (resin solution to which a solvent is added if necessary) using a mixer or the like, and if necessary, dried and granulated or pasted. A metal-magnetic composite material having a shape (for example, a viscosity of 30 Pa · s or more and 3000 Pa · s or less) is prepared. Here, if necessary, a dispersant, a plasticizer, or the like may be appropriately added before mixing and dispersing. Further, in these mixing ratios, the volume occupancy of the thermosetting resin in the total volume of the materials used for the metal magnetic composite material is 12.1 vol% or more, and the volume of the non-magnetic inorganic powder with respect to the volume of the thermosetting resin. The ratio of is 5.0 vol% or more and less than 200.0 vol%.
The order of addition of the metallic magnetic powder, the non-magnetic inorganic powder, the thermosetting resin and the solvent is not particularly limited. Then, the above mixing may be kneaded granulation. Further, when a granular metal magnetic material is obtained by granulation, it may be mixed and then classified. Examples of the classification method include sieving classification, inertial classification, dry classification such as centrifugal classification, and wet classification such as sedimentation classification. When a solvent is used, it is preferable to dry the mixture after mixing to bring the solvent content to approximately 0 wt%.

[Compression molding process]
The metal magnetic composite material obtained in the above material preparation step is filled in the die from the die opening of the press machine by an injector or the like. The shape and size of this mold are not particularly limited. Further, when the metal magnetic composite material is charged into the mold, the metal magnetic composite material may be charged while applying vibration in order to prevent the occurrence of a portion where the metal magnetic composite material is not sufficiently filled inside the mold.
Next, from either the upper or lower side of the mold or one of them, a movable punch (press head) is applied to the metal magnetic composite material in the mold, for example, 1 [ton / cm ² ] or more and 10 [ton] under normal pressure conditions. / Cm ² ] or less, the volume occupancy of the pores with respect to the total volume is 10.0 vol% or less, preferably less than 8.0 vol%, more preferably 6.0 vol% or less, still more preferably 5.0 vol. Compress and mold to less than%. In addition, in this compression molding, in order to make it easy to reduce the volume occupancy of the pores with respect to the total volume, similarly under reduced pressure conditions (for example, 10 kPa or less), 1 [ton / cm ² ] or more and 10 [ton / cm ² ] or less It may be molded by the pressure of. When the metal magnetic composite material is in the form of a paste, it may be molded by applying a pressure of 2 [kg / cm ² ] or more and 300 [kg / cm ² ] or less under reduced pressure conditions. As a result, a molded product of a metal magnetic composite material is obtained.

In the compression molding step, the thermosetting resin is softened by heating it below the thermosetting temperature and above the softening temperature by heating the mold or the like, and is softened by 2 [kg / cm ² ] or more and 300 [kg / kg /. It may be compression molded (hot pressed) with a pressure of cm ² ] or less.
Further, the metal magnetic composite material is put into a concave tray instead of a mold, a metal pressure part having a rubber tip is placed on the tray, and the tray and the pressure part are put together with water or Compression molding may be performed by hydraulic molding in which the oil is immersed in a liquid layer in which the oil is stored, and a load is further applied to the pressurized part to pressurize the metal magnetic composite material.

[Thermosetting process]
The molded product is taken out from the mold, and the molded product of the metal magnetic composite material is thermally cured at a temperature equal to or higher than the thermosetting temperature of the thermosetting resin. The thermosetting time is also not particularly limited, and may be, for example, 0.1 hour or more and 5 hours or less, and further 0.2 hours or more and 1 hour or less. After that, the thermosetting body of the obtained metal magnetic composite material is further selectively subjected to steps such as surface polishing and coating, if necessary.

In this way, in the present embodiment, a thermosetting body of a metal magnetic composite material having a low volume occupancy of pores can be obtained by eliminating air as much as possible at the time of manufacturing. The gas (particularly water vapor) permeability of the thermosetting material is significantly reduced. A decrease in gas permeability causes an increase in internal pressure due to the generation of water vapor in the MSL test, but the thermosetting body of the metal magnetic composite material according to the present embodiment has extremely high strength due to the above design and is sufficient for this internal pressure. As a result, cracks, cracks, and deterioration of characteristics are unlikely to occur.
This is because the strength of the non-magnetic inorganic powder that fills the space between the particles of the metal magnetic powder and the cured resin product is higher, so the strength of the thermosetting body against cohesive failure is further improved, and the vaporized vapor is not instantly released to the outside. However, in the MSL test, it can be estimated that the occurrence of cracks and cracks is suppressed.

<Manufacturing method of coil parts>
When a coil component including a magnetic core material composed of a thermosetting body of a metal magnetic composite material according to the present embodiment is manufactured, this is also not limited, but the metal magnetism according to the above-described embodiment. As a modified example of the method for producing a thermosetting composite material, it can be produced by, for example, the method shown in FIG.
Specifically, first, an air-core coil with a winding made of a wire such as a round wire is prepared. The air-core coil is composed of a winding portion 11 around which an insulatingly coated wire is wound and both end portions 12 of a winding drawn from the winding portion 11 (FIG. 1A). ). Next, this air-core coil is placed in the die 21 of the press machine, and the coil winding portion 11 (including the inside of the loop of the wound wire and the gap between the loops) is embedded through the opening of the die 21. As described above, the metal magnetic composite material 22 prepared by the material preparation step described above is filled. However, both ends 12 of the winding are exposed from the metal magnetic composite material 22 ((b) in FIG. 1). Then, under the same conditions as the compression molding step described above, compression molding is performed by the upper punch so that the volume occupancy of the pores is within a predetermined range, and the metal magnetic composite material 22 and the coil are integrated ((FIG. 1). c)). After that, the molded body is taken out from the mold, and a thermosetting step is performed at a temperature equal to or higher than the thermosetting temperature of the thermosetting resin, so that the metal magnetic composite material 22 is molded into a substantially rectangular shape and the magnetic core material 32 (thermosetting) A coil is embedded in a magnetic exterior body and a magnetic core), and both ends 12 of the winding get a coil component exposed to the outside (FIG. 1 (d)).

Instead of the air-core coil, a coil assembly made of a coil and a magnetic core material serving as a magnetic core may be prepared, and a coil component may be manufactured by the same method as described above. In this case, the magnetic exterior body (outer core material) is composed of the thermosetting body of the metal magnetic composite material according to the present embodiment, but the magnetic core (inner core material) is different from the metal magnetic composite material according to the present embodiment. It may be a coil component composed of a molded body of a material (for example, a ferrite core).

The thermosetting body of the metal magnetic composite material according to the present embodiment, the coil parts including the magnetic core material containing the thermosetting body, and the manufacturing method thereof have been described above, but the present invention is limited to the above-described embodiment. However, it also includes various modifications, improvements, and the like as long as the object of the present invention is achieved.
In addition, each of the above embodiments can be appropriately combined as long as the gist of the present invention is not deviated.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples, and various modifications and the like can be made within the technical idea of the present invention.

<Test I>
As materials, a bisphenol type one-component epoxy resin which is a thermocurable type and is solid at room temperature, and a spherical silica powder whose surface is hydrophobized and prepared by a sol-gel method (average particle size (D ₅₀ ): 0.1 um) and a metallic magnetic powder (average particle size (D ₅₀ ): 10 um) which is an Fe—Si—Cr based alloy powder were prepared. Here, the average particle size (D ₅₀ ) was measured using a laser diffraction / scattering type particle size distribution measuring device (particle size distribution) LA-960 (manufactured by HORIBA, Ltd.) (Tests II to be described later). The same applies to V).
Then, a solvent (methyl ethyl ketone) is mixed with the epoxy resin to prepare a resin solution, the spherical silica powder is sufficiently mixed and dispersed in the resin solution so as to have a predetermined volume ratio, and the metal magnetic powder is further mixed and dispersed in a predetermined volume ratio. It was mixed and dispersed so as to have a volume ratio (samples 5 to 9). Samples 1 to 4 and control (Ct) were prepared without blending spherical silica powder. Then, the solvent was dried while mixing and stirring to obtain a granular formulation (samples 1 to 9 and control). These were used as metal magnetic composite materials.

Next, an air-core coil in which an insulating coated copper wire was wound for 20 turns was prepared. This coil was installed in a mold, a required amount of each of the metal magnetic composite materials of Samples 1 to 9 was charged, and the mold was closed with an upper punch. Then, this mold was used for compression molding so as to have a target density set with a pressure of 10 [ton / cm ² ] as the upper limit, and then the molded product was taken out from the mold. The removed molded product was heat-treated under the conditions of 150 ° C. for 2 hours to heat-cure the epoxy resin. Then, an electrode was connected to the lead end of the coil in the thermosetting body (coil component of Samples 1 to 9) of the metal magnetic composite material embedding the obtained coil.
Separately, only the above samples 1 to 9 and the control metal magnetic composite material were filled in a mold, and similarly compression-molded and thermoset, a plate having a length of 15 mm, a width of 5 mm, and a thickness of 0.5 mm. Magnetic core materials (samples 1-9 and controls) were also made.
The volume occupancy of the metal magnetic powder, the epoxy resin, the spherical silica powder and the pores in the thermosetting body of the samples 1 to 9 and the control metal magnetic composite material, and the volume of the spherical silica powder and the epoxy resin. The ratio and the target density of compression molding are shown in Table 1 below. Here, the volume occupancy of each of the above is the weight and specific gravity of each of the above materials (the specific gravity of the metal magnetic powder is 7.61 g / cm ³ , the specific gravity of the epoxy resin is 1.17 g / cm ³ , and the specific gravity of the spherical silica powder is 2. It is calculated from .2 g / cm ³ ) and the weight and volume of the heat-cured body of the metal magnetic composite material.

Then, the strength of the samples 1 to 9 and the control plate-shaped magnetic core material was measured, and the MSL test was performed on the coil parts of the samples 1 to 9.
Specifically, the strength was measured by performing a three-point bending test on a plate-shaped magnetic core material at a distance of 7 mm between fulcrums using an autograph, and measuring the breaking strength (bending strength) of the material.
Further, the MSL test of the coil parts was carried out by the following method corresponding to MSL level 1 in accordance with JIS61760-4 (2016). First, it is dried (moisture removed) at 125 ± 5 ° C for 24 hours or more, then humidified (absorbed) at a temperature of 85 ° C and humidity of 85% RH for 168 hours, and within a certain period of time, the peak temperature is 260 ° C (compatible with lead-free solder). The temperature was loaded by passing it through the reflow furnace of the above as many times as necessary. Then, as a characteristic inspection, the inductance (L value) was confirmed with an LCR meter (E4980A LCR Meter manufactured by Agilent), and it was evaluated whether or not it was within the standard. In addition, as an appearance inspection, the appearance was inspected with an optical microscope having a magnification of 40 times, and the presence or absence of cracks, peeling, expansion, etc. was evaluated.

The test results are also shown in Table 1 below. The bending strength result is shown as a bending strength ratio when the bending strength of the control is 1.00. As for the MSL test results, those with an appearance evaluation (occurrence rate of cracks, etc.) of 0 and a characteristic evaluation (inductance change rate) of -5% or less are ○, and minor cracks, etc. are generated, but the inductance change rate. The value of -5% or less was evaluated as Δ, and the rate of change in inductance that did not fall within -5% was evaluated as x.

From these test results, by using a metal magnetic composite material containing hydrophobic spherical silica powder, a metal that has high bending strength and can withstand the MSL test even if the volume occupancy of the pores is 10.0 vol% or less. It has been clarified that a thermosetting body (magnetic core material, coil parts) of a magnetic composite material can be obtained.

<Test II>
As materials, a bisphenol type one-component epoxy resin which is a thermocurable type and is solid at room temperature, and a spherical silica powder whose surface is hydrophobized and prepared by a sol-gel method (average particle size (D ₅₀ ): 0.1 um) and a metallic magnetic powder (average particle size (D ₅₀ ): 10 um) which is an Fe—Si—Cr based alloy powder were prepared.
Then, a solvent (methyl ethyl ketone) is mixed with the epoxy resin to prepare a resin solution, the spherical silica powder is sufficiently mixed and dispersed in the resin solution so as to have a predetermined volume ratio, and the metal magnetic powder is further mixed and dispersed in a predetermined volume ratio. It was mixed and dispersed so as to have a volume ratio. Then, the solvent was dried while mixing and stirring to obtain a granular composition (Samples 10 to 42). These were used as metal magnetic composite materials.

Next, using each of the above metal magnetic composite materials, a coil component and a plate-shaped magnetic core material (samples 10 to 42) were produced by the same method as in Test I.
The volume occupancy of the metal magnetic powder, the epoxy resin, the spherical silica powder and the pores in the thermosetting body of the metal magnetic composite material of the samples 10 to 42, and the volume ratio of the spherical silica powder to the epoxy resin, The target densities for compression molding are shown in Table 2 below (the specific gravities of the above materials are the same as in Test I).

Then, the bending strength was measured and the MSL test was carried out on the samples 10 to 42 by the same method as in Test I. The test results are also shown in Table 2 below.

From these test results, the volume occupancy of the metal magnetic composite material with respect to the total volume of the thermosetting body was 11.0 vol% or more of the epoxy resin, and 1/10 of the volume of the metal magnetic powder with respect to the volume of the epoxy resin. By setting the volume ratio of the hydrophobic spherical silica powder having an average particle size (D ₅₀ ) to 5.3 vol% or more and less than 200.0 vol%, bending is performed even if the volume occupancy of the pores is 3.0 vol%. It has been clarified that a thermosetting body (magnetic core material, coil component) of a metal magnetic composite material having high strength and capable of withstanding the MSL test can be obtained.

<Test III>
As materials, a bisphenol type one-component epoxy resin which is a thermocurable type and is solid at room temperature, and an average particle size (D ₅₀ ) prepared by a sol-gel method or a synthetic melting method and having a hydrophobic treatment on the surface. A plurality of spherical silica powders having different values and a plurality of metal magnetic powders having different average particle diameters (D ₅₀ ), which are Fe—Si—Cr based alloy powders, were prepared.
Then, a solvent (methyl ethyl ketone) is mixed with the epoxy resin to prepare a resin solution, the spherical silica powder is sufficiently mixed and dispersed in the resin solution so as to have a predetermined volume ratio, and the metal magnetic powder is further mixed and dispersed in a predetermined volume ratio. It was mixed and dispersed so as to have a volume ratio. Then, the solvent was dried while mixing and stirring to obtain a granular composition (Samples 43 to 62). These were used as metal magnetic composite materials.

Next, using each of the above-mentioned metal magnetic composite materials, coil parts and plate-shaped magnetic core materials (samples 43 to 62) were produced by the same method as in Test I.
The average particle size of the metal magnetic powder and the spherical silica powder (D ₅₀ ) and the average particle size of the spherical silica powder relative to the average particle size (D ₅₀ ) of the heat-cured material of the metal magnetic composite material of the samples 43 to 62. Particle size (D ₅₀ ) ratio (average particle size ratio), volume occupancy of metal magnetic powder, epoxy resin, spherical silica powder and pores to total volume, volume ratio of spherical silica powder to epoxy resin, and compression The target densities for molding are shown in Table 3 below (the specific gravity of each of the above materials is the same as in Test I).

Then, the bending strength was measured and the MSL test was carried out on the samples 43 to 62 by the same method as in Test I. The test results are also shown in Table 3 below.

From these test results, in the metal magnetic composite material, the average particle size (D ₅₀ ) of the hydrophobic spherical silica powder contained in the volume ratio of 50.0 vol% with respect to the volume of the epoxy resin was determined by the average particles of the metal magnetic powder. By making the diameter (D ₅₀ ) 1/10 or less, even if the volume occupancy of the pores is 3.0 vol%, the thermocured body of the metal magnetic composite material having high bending strength and capable of withstanding the MSL test ( It has become clear that magnetic core materials and coil parts) can be obtained.

<Test IV>
The materials are a heat-curable, bisphenol-type one-component epoxy resin that is liquid at room temperature, and a spherical silica powder that has been prepared by the sol-gel method and whose surface has been hydrophobized (average particle size (D ₅₀ ): 0). .1um) and metal magnetic powder (average particle size (D ₅₀ ): 10um) which is an Fe—Si—Cr based alloy powder were prepared.
Then, the spherical silica powder was mixed and dispersed in the epoxy resin so as to have a predetermined volume ratio, and the metal magnetic powder was further mixed and dispersed so as to have a predetermined volume ratio. Then, the mixture was mixed and stirred to obtain a paste-like formulation (Samples 63 to 67). These were used as metal magnetic composite materials.

Next, an air-core coil in which an insulating coated copper wire was wound for 20 turns was prepared. This coil was installed in the mold, the required amount of each of the above metal-magnetic composite materials was charged, and the mold was closed with an upper punch. Then, the entire mold was depressurized to 10 kPa, and the compact was further compression-molded at a pressure of 200 [kg / cm ² ] while still under reduced pressure, and then returned to atmospheric pressure, and the molded product was taken out from the mold. Then, the taken-out molded product was heat-treated at 150 ° C. for 2 hours to heat-cure the epoxy resin. Then, an electrode was connected to the lead wire end of the coil in the thermosetting body (coil component of samples 63 to 67) of the metal magnetic composite material embedding the obtained coil.
Separately from this, a plate-shaped magnetic core material (sample 63) having a length of 15 mm, a width of 5 mm, and a thickness of 0.5 mm, in which only each of the above metal magnetic composite materials was filled in a mold, and similarly compression-molded and thermoset. ~ 67) was also produced.
The volume occupancy of the metal magnetic powder, the epoxy resin, the spherical silica powder and the pores in the thermosetting body of the metal magnetic composite material of the samples 63 to 67, and the volume ratio of the spherical silica powder to the epoxy resin, The target densities for compression molding are shown in Table 4 below (the specific gravities of the above materials are the same as in Test I).

Then, for these samples 63 to 67, the bending strength was measured and the MSL test was carried out by the same method as in Test I. The test results are also shown in Table 4 below.

From these test results, the volume occupancy of the metal magnetic composite material with respect to the total volume of the thermosetting body was set to 20.0 vol% or more, and 1/10 of the volume of the metal magnetic powder with respect to the volume of the epoxy resin. By setting the volume ratio of the hydrophobic spherical silica powder having an average particle size (D ₅₀ ) to 5.3 vol% or more and less than 200.0 vol%, bending is performed even if the volume occupancy of the pores is 3.0 vol%. It has been clarified that a thermosetting body (magnetic core material, coil component) of a metal magnetic composite material having high strength and capable of withstanding the MSL test can be obtained.

<Test V>
As a material, it was prepared by a heat-curable, bisphenol-type one-component epoxy resin that is liquid at room temperature, a sol-gel method, a flame melting method (synthetic silica powder, natural mineral silica powder), or a fumes method. Spherical silica powder (sol-gel method is one type without surface hydrophobic treatment, the other is two types with or without surface hydrophobic treatment, average particle size (D ₅₀ ): 0.1um) and Fe-Si-Cr. A metal magnetic powder (average particle size (D ₅₀ ): 10 um), which is a system alloy powder, was prepared.
Then, the spherical silica powder was mixed and dispersed in the epoxy resin so as to have a predetermined volume ratio, and the metal magnetic powder was further mixed and dispersed so as to have a predetermined volume ratio. Then, a paste-like formulation was obtained by mixing and stirring (Samples 68 to 74). These were used as metal magnetic composite materials.

Then, using each of the above-mentioned metal magnetic composite materials, coil parts and plate-shaped magnetic core materials (samples 68 to 74) were produced by the same method as in Test IV. In addition, as a sample containing spherical silica powder prepared by the sol-gel method and hydrophobized on the surface, the coil parts and the plate-shaped magnetic core material of Sample 8 of Test I were also prepared.
In addition, in the thermosetting body of the metal magnetic composite material of Samples 68 to 74 and Sample 8, the preparation method of the spherical silica powder used, the presence or absence of the hydrophobic treatment, the metal magnetic powder, the epoxy resin, the spherical silica powder and the empty with respect to the total volume. The volume occupancy of each pore, the volume ratio of the spherical silica powder to the epoxy resin, and the target density of compression molding are shown in Table 5 below (the specific gravity of each of the above materials is the same as in Test I).

Then, for these samples 68 to 74, the bending strength was measured and the MSL test was carried out by the same method as in Test I. The test results of this test and the test results of sample 8 of test I, which is a comparative sample, are also shown in Table 5 below.

From these test results, by assuming that the spherical silica powder to be blended in the metal magnetic composite material is prepared by the sol-gel method or the flame melting method, bending is performed even if the volume occupancy of the pores is 3.0 vol%. It was shown that a thermosetting body having high strength and capable of withstanding the MSL test can be obtained. Further, it has been clarified that a thermosetting body (magnetic core material, coil component) of a metal magnetic composite material having higher bending strength can be obtained by hydrophobizing the surface of the spherical silica powder.

Based on the above, the epoxy resin, the Fe—Si—Cr alloy powder, and the spherical silica powder are contained, and the volume occupancy of the epoxy resin with respect to the total volume of the heat-cured material is set to 11.0 vol% or more, and the volume of the pores is set. The occupancy rate is 10 vol% or less, the volume ratio of the spherical silica powder to the volume of the epoxy resin is 5.3 vol% or more and less than 200.0 vol%, and the average particle diameter (D ₅₀ ) of the spherical silica powder is Fe-Si-Cr. By using a thermohardened metal magnetic composite material with an average particle size (D ₅₀ ) of 1/10 or less of the system alloy powder, the volume occupancy of the pores is low and the bending strength is very high (bending strength ratio). Is 1.90 or more), and it has been shown that a magnetic core material or coil component that clears MSL level 1 can be obtained.

The present embodiment includes the following technical ideas.
(1) A thermosetting body of a metal magnetic composite material containing a thermosetting resin, a metal magnetic powder obtained by powdering a metal magnetic material, and a non-magnetic inorganic powder obtained by powdering a non-magnetic inorganic material. The volume occupancy of the thermosetting resin with respect to the total volume of the thermosetting body is 11.0 vol% or more, and the volume occupancy of the pores with respect to the total volume of the thermosetting body is 10.0 vol% or less. The ratio of the volume of the non-magnetic inorganic powder to the volume of the thermosetting resin is 5.0 vol% or more and less than 200.0 vol%, and the average particle size (D ₅₀ ) of the non-magnetic inorganic powder is that of the metal magnetic powder. A thermosetting body of a metal magnetic composite material having an average particle size (D ₅₀ ) or less.
(2) The thermosetting body of a metal-magnetic composite material according to (1), wherein the non-magnetic inorganic powder is a hydrophobic non-magnetic inorganic powder whose surface has been hydrophobized.
(3) The thermosetting body of the metal magnetic composite material according to (1) or (2), wherein the non-magnetic inorganic powder is spherical silica powder.
(4) The thermosetting body of the metal magnetic composite material according to (3), wherein the spherical silica powder is prepared by a sol-gel method or a melting method.
(5) The thermosetting body of a metal magnetic composite material according to any one of (1) to (4), wherein the thermosetting resin is an epoxy resin.
(6) The thermosetting body of a metal magnetic composite material according to any one of (1) to (5), wherein the metal magnetic powder is an insulated metal magnetic powder whose surface is heat-insulated.
(7) A coil component including a coil and a magnetic core material, wherein at least a part of the magnetic core material is a thermosetting body of the metal magnetic composite material according to any one of (1) to (6). Coil parts made up of.
(8) The ratio of the volume to the volume of the thermosetting resin having a volume occupancy of 12.1 vol% or more with respect to the total volume of the material, the metal magnetic powder obtained by pulverizing the metal magnetic material, and the thermosetting resin is 5 less than .0Vol% or more 200.0Vol%, and, is 1/10 or less of the average particle diameter _{(D 50)} mean particle diameter of the metal magnetic powder _{(D 50),} the non-magnetic inorganic material and powdered A material preparation step of mixing a non-magnetic inorganic powder and a solvent to obtain a metal magnetic composite material, and compressing the metal magnetic composite material until the volume occupancy of pores with respect to the total volume is 10.0 vol% or less. Thermosetting of a metal magnetic composite material comprising a compression molding step of molding to obtain a molded body of the metal magnetic composite material and a thermosetting step of thermosetting the molded body to obtain a thermosetting body of the metal magnetic composite material. How to make a body.

11 Coil winding part 12 Both ends of the coil 21 Mold 22 Metal magnetic composite material 32 Magnetic core material (outer core material and inner core material that are heat-cured materials of the metal magnetic composite material)

Claims (8)

A thermosetting body of a metal magnetic composite material containing a thermosetting resin, a metal magnetic powder obtained by pulverizing a metal magnetic material, and a non-magnetic inorganic powder obtained by pulverizing a non-magnetic inorganic material.
The volume occupancy of the thermosetting resin with respect to the total volume of the thermosetting body is 11.0 vol% or more.
The volume occupancy of the pores with respect to the total volume of the thermosetting body is 10.0 vol% or less.
The ratio of the volume of the non-magnetic inorganic powder to the volume of the thermosetting resin is 5.0 vol% or more and less than 200.0 vol%.
The average particle size (D ₅₀ ) of the non-magnetic inorganic powder is 1/10 or less of the average particle size (D ₅₀ ) of the metal magnetic powder.
Thermosetting body of metal magnetic composite material. The thermosetting body of a metallic magnetic composite material according to claim 1, wherein the non-magnetic inorganic powder is a hydrophobic non-magnetic inorganic powder whose surface has been hydrophobized. The thermosetting body of a metallic magnetic composite material according to claim 1 or 2, wherein the non-magnetic inorganic powder is spherical silica powder. The thermosetting body of the metal magnetic composite material according to claim 3, wherein the spherical silica powder is prepared by a sol-gel method or a melting method. The thermosetting body of a metal magnetic composite material according to any one of claims 1 to 4, wherein the thermosetting resin is an epoxy resin. The thermosetting body of a metal magnetic composite material according to any one of claims 1 to 5, wherein the metal magnetic powder is an insulated metal magnetic powder whose surface is insulated. A coil component including a coil and a magnetic core material.
A coil component in which at least a part of the magnetic core material is made of a thermosetting body of the metal magnetic composite material according to any one of claims 1 to 6. Thermosetting resin having a volume occupancy of 12.1 vol% or more with respect to the total volume of the material,
Metallic magnetic powder, which is a powder of metallic magnetic material,
The volume ratio of the thermosetting resin to the volume is 5.0 vol% or more and less than 200.0 vol%, and the average particle size (D ₅₀ ) is 1 / of the average particle size (D ₅₀ ) of the metal magnetic powder. A non-magnetic inorganic powder obtained by powdering a non-magnetic inorganic material having a volume of 10 or less,
A material preparation process in which a solvent is mixed to obtain a metallic magnetic composite material,
A compression molding step of obtaining a molded body of the metal magnetic composite material by compression molding the metal magnetic composite material until the volume occupancy of the pores with respect to the total volume is 10.0 vol% or less.
A thermosetting step of thermosetting the molded body to obtain a thermosetting body of a metal magnetic composite material.
A method for producing a thermosetting body of a metal magnetic composite material.

Images