JP2022047978A - Magnetic resin composition, and molding - Google Patents

Abstract

To provide a magnetic resin composition that can give a molding having high chemical resistance.SOLUTION: A magnetic resin composition 1 includes a magnetic filler 2, and a resin material 3. The magnetic filler 2 includes a first iron-nickel alloy filler 21, and a second iron-nickel alloy filler 22 having an average particle size smaller than that of the first iron-nickel alloy filler 21. Relative to the total mass of the first iron-nickel alloy filler 21 and the second iron-nickel alloy filler 22, the content of nickel is more than 39 mass%.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a magnetic resin composition and a molded body in general, and more particularly to a magnetic resin composition containing a magnetic filler and a resin material, and a molded body.

Patent Document 1 discloses a composite magnetic encapsulation material. This composite magnetic encapsulation material comprises a resin material and a filler. The filler is blended with the resin material, and the blending ratio is 30 to 85% by volume. Further, the filler contains a magnetic filler. This magnetic filler contains 32 to 39% by weight of a metal material containing Ni as a main component in Fe. As a result, the composite magnetic encapsulation material has a coefficient of thermal expansion of 15 ppm / ° C or less.

Japanese Unexamined Patent Publication No. 2017-188646

However, the present inventors have found that the composite magnetic encapsulation material of Patent Document 1 has a problem of low chemical resistance.

An object of the present disclosure is to provide a magnetic resin composition and a molded product capable of obtaining a molded product having high chemical resistance.

The magnetic resin composition according to one aspect of the present disclosure contains a magnetic filler and a resin material. The magnetic filler includes a first iron-nickel alloy filler and a second iron-nickel alloy filler having an average particle size smaller than the average particle size of the first iron-nickel alloy filler. The nickel content is more than 39% by mass with respect to the total mass of each of the first iron-nickel alloy filler and the second iron-nickel alloy filler.

The molded product according to one aspect of the present disclosure includes a cured product of the magnetic resin composition.

According to the present disclosure, a molded product having high chemical resistance can be obtained.

FIG. 1 is a schematic cross-sectional view schematically showing a magnetic resin composition according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view schematically showing a magnetic resin composition according to another embodiment of the present disclosure.

1. 1. Outline The magnetic resin composition 1 according to the present embodiment contains a magnetic filler 2 and a resin material 3 (see FIG. 1). The magnetic filler 2 includes a first iron-nickel alloy filler 21 and a second iron-nickel alloy filler 22. The second iron-nickel alloy filler 22 has an average particle diameter smaller than the average particle diameter of the first iron-nickel alloy filler 21. As a result, the magnetic filler 2 can be highly filled, and the molded product of the magnetic resin composition 1 has magnetic properties. Further, the nickel content is more than 39% by mass with respect to the total mass of each of the first iron-nickel alloy filler 21 and the second iron-nickel alloy filler 22. As described above, since the nickel content is higher than that of the conventional iron-nickel alloy filler, the chemical resistance of the molded product is improved. Therefore, even if the molded product is exposed to the chemical, the molded product can maintain the magnetic properties before being exposed to the chemical.

Therefore, according to the magnetic resin composition 1 according to the present embodiment, a molded product having high chemical resistance can be obtained.

2. 2. Details <Magnetic resin composition>
The magnetic resin composition 1 according to the present embodiment contains a magnetic filler 2 and a resin material 3 (see FIG. 1). The magnetic resin composition 1 may further contain a solvent. The form of the magnetic resin composition 1 is, for example, a paste, but a form other than the paste may be used.

≪Magnetic filler≫
The magnetic filler 2 is a powdery substance that can be magnetized. As described above, when the magnetic resin composition 1 contains the magnetic filler 2, a molded product having magnetic properties can be obtained. Magnetic properties are magnetic properties that are exhibited when magnetized. Specific examples of the magnetic characteristics include magnetic permeability and magnetic flux density.

As described above, the molded product has magnetic properties, but the molded product according to the present embodiment can have a high magnetic permeability at a high frequency. The high frequency frequency band is, for example, several MHz or more and several GHz or less, and includes 10 MHz. Permeability specifically means complex relative permeability ( _μr ). The complex relative permeability (μ _r ) is expressed by the formula μ _r = μ / μ ₀ (μ: complex permeability, μ ₀ : vacuum permeability). The complex magnetic permeability (μ) is expressed by the formula μ = μ'-iμ "(μ': real part, μ": imaginary part, i: imaginary unit).

The magnetic resin composition 1 may further contain a non-magnetic filler. The non-magnetic filler is a non-magnetic powdery substance.

[Magnetic filler]
The magnetic filler 2 includes a first iron-nickel alloy filler 21 and a second iron-nickel alloy filler 22. The second iron-nickel alloy filler 22 has an average particle diameter smaller than the average particle diameter of the first iron-nickel alloy filler 21 (see FIG. 1). As a result, the magnetic filler 2 can be highly filled, and the molded product of the magnetic resin composition 1 has magnetic properties. Hereinafter, the term simply iron-nickel alloy filler means both the first iron-nickel alloy filler 21 and the second iron-nickel alloy filler 22.

The iron-nickel alloy filler is a magnetic filler 2 made of an iron-nickel alloy. An iron-nickel alloy is a eutectic containing an iron element and a nickel element. The eutectic of the iron-nickel alloy may further contain an element of molybdenum.

The nickel content is more than 39% by mass, preferably 45% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, based on the total mass of the iron-nickel alloy filler. be.

As described above, since the nickel content is higher than that of the conventional iron-nickel alloy filler, the chemical resistance of the molded product is improved. Here, the chemical resistance is a property that the molded product is not significantly deteriorated by the treatment of chemicals. The chemical treatment is not particularly limited, and examples thereof include desmear treatment, electroless plating, and electrolytic plating. Examples of the chemicals include chemicals for desmear treatment (chromic acid, sulfuric acid, neutralizers, conditioners, hydrofluoric acid, etc.), chemicals for electroless plating treatment, and plating solutions for electrolytic plating. The chemicals also include chemicals used for pre- and post-plating treatments. For example, acids such as sulfuric acid used in pretreatments for electroless plating (soft etching, pickling, predip, etc.) are also included.

When the chemical resistance of the molded product is increased, the molded product after being treated with the chemical can easily maintain the performance of the molded product before being treated with the chemical. That is, even if the molded product having magnetic properties is exposed to chemicals, the molded product can maintain the magnetic properties before being exposed to the chemicals. As described above, the molded product according to the present embodiment does not easily deteriorate in magnetic properties even when treated with chemicals.

Further, since the nickel content is higher than that of the conventional iron-nickel alloy filler, the machinability of the molded product is improved. Here, the machinability is a degree indicating the ease of machining of a molded product. The machinability is not particularly limited, and examples thereof include hole machinability. The hole workability is a degree indicating the ease of processing the molded body when drilling a through hole in the molded body. The hole workability can be evaluated, for example, by the degree of wear of the drill bit.

When the machinability of the molded body, particularly the hole workability, is improved, for example, wear of the drill bit, unevenness of the hole wall, and generation of smear are reduced.

The upper limit of the nickel content with respect to the total mass of the iron-nickel alloy filler is not particularly limited, but is preferably 90% by mass or less, more preferably 85% by mass or less.

The content of the magnetic filler 2 is preferably less than 90% by volume, more preferably 85% by volume or less, still more preferably 75% by volume or less, based on the total volume of the magnetic resin composition 1. When the content of the magnetic filler 2 is less than 90% by volume, the thickening of the magnetic resin composition 1 can be suppressed, and the deterioration of the vacuum print filling property can be suppressed. Here, the vacuum print filling property means that when the magnetic resin composition 1 is filled in a hollow portion such as a through hole of a substrate by using a screen printing method under vacuum, an unfilled hollow portion is unlikely to occur. Further, it means that bubbles (voids) are less likely to be mixed in the magnetic resin composition 1 filled in the cavity.

Further, when the content of the magnetic filler 2 is less than 90% by volume, the machinability can be improved. In particular, the hole workability can be improved.

Further, when the content of the magnetic filler 2 is less than 90% by volume, the magnetic loss at a high frequency can be reduced. Specifically, the loss coefficient (tan δ) can be reduced. The loss coefficient (tan δ) is expressed by the equation tan δ = μ ”/ μ’.

The content of the magnetic filler 2 is preferably 30% by volume or more, more preferably 35% by volume or more, still more preferably more than 40% by volume, based on the total volume of the magnetic resin composition 1. When the content of the magnetic filler 2 is 30% by volume or more, the magnetic permeability at high frequencies can be further increased.

The average particle size of the first iron-nickel alloy filler 21 is preferably less than 24 μm. This makes it possible to improve machinability. In addition, the eddy current loss is reduced, and the magnetic loss at high frequencies can be reduced. The average particle size of the first iron-nickel alloy filler 21 is preferably 5 μm or more. In the present specification, the average particle size is the particle size at an integrated value of 50% in the particle size distribution measured based on the particle size distribution measuring device based on the laser scattering / diffraction method, that is, the 50% volume average particle size (D50). ) Means.

The average particle size of the second iron-nickel alloy filler 22 is preferably more than 1 μm. As a result, the thickening of the magnetic resin composition 1 can be suppressed, and the deterioration of the vacuum print filling property can be suppressed. The average particle size of the second iron-nickel alloy filler 22 is preferably 7 μm or less.

The average particle size of the second iron-nickel alloy filler 22 is preferably 0.1 times or more and 0.9 times or less the average particle size of the first iron-nickel alloy filler 21, more than 0.1 times and 0. More preferably, it is less than 8 times. This makes it possible to increase the filling of the magnetic filler 2.

The content of the first iron-nickel alloy filler is preferably 50 parts by mass or more and 100 parts by mass or less, and more preferably 60 parts by mass or more and 98 parts by mass or less with respect to 100 parts by mass of the total of the magnetic filler 2.

The content of the second iron-nickel alloy filler is preferably 2 parts by mass or more and 50 parts by mass or less, and more preferably 5 parts by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the total of the magnetic filler 2.

The iron-nickel alloy filler preferably contains spherical particles (see FIG. 1). This makes it possible to increase the filling of the iron-nickel alloy filler. That is, when the iron-nickel alloy filler contains spherical particles, the filling amount of the iron-nickel alloy filler in the magnetic filler 2 can be increased as compared with the case where the iron-nickel alloy filler does not contain spherical particles. The iron-nickel alloy filler may contain particles having a shape other than the spherical shape. The shape other than the spherical shape is not particularly limited, and examples thereof include an ellipsoidal shape, a flat shape, a crushed shape, and an indefinite shape.

As described above, when the iron-nickel alloy filler is highly filled, the magnetic permeability of the molded product can be increased. Further, the fluidity of the magnetic resin composition 1 can be improved. That is, it becomes easy to mold the molded body.

Here, the case where the surface of the iron-nickel alloy filler is covered with the insulating layer (first case) and the case where the surface of the iron-nickel alloy filler is not covered with the insulating layer (second case). By comparison, the first case is preferable. That is, preferably, the surface of the iron-nickel alloy filler is covered with an insulating layer. More specifically, the surface of the individual particles constituting the iron-nickel alloy filler is coated with an insulating layer. In the second case, it is considered that the individual particles come into contact with each other and behave as a large mass of particles, but in the first case, the contact of the individual particles is suppressed by the insulating layer. Therefore, the insulating layer can suppress the generation of eddy currents flowing between the particles of the adjacent iron-nickel alloy filler. By reducing the eddy current loss in this way, the magnetic loss can be reduced.

The magnetic filler 2 preferably further contains a ferrite 23 (see FIG. 2). Ferrite 23 is a ceramic filler containing iron oxide as a main component. When the magnetic filler 2 further contains the ferrite 23, the magnetic permeability at a high frequency can be further increased.

Ferrites include soft ferrites exhibiting soft magnetism and hard ferrites exhibiting hard magnetism. Ferrites are classified into spinel ferrites, hexagonal ferrites, garnet ferrites, and the like according to their crystal structures.

Spinel ferrite has a spinel-type crystal structure. The composition formula of spinel ferrite is represented by AFe ₂ O ₄ (A is Mn, Co, Ni, Cu, Zn, etc.). Most of the spinel ferrites are soft ferrites. Spinel ferrite includes, for example, manganese-zinc ferrite, nickel-zinc ferrite, copper-zinc ferrite and the like. Since spinel ferrite has high magnetic permeability and electrical resistance, the eddy current loss in the high frequency frequency band is small. Magnetite is also a type of spinel ferrite. The composition formula of magnetite is represented by Fe ₃ O ₄ .

Hexagonal ferrite has a magnetoplumbite-type hexagonal crystal structure. The composition formula of the hexagonal ferrite is represented by AFe ₁₂ O ₁₉ (A is Ba, Sr, Pb, etc.). Hexagonal ferrite is also called magnetoplambite-type ferrite or M-type ferrite. Hexagonal ferrite has a larger magnetic anisotropy than spinel ferrite, so it exhibits a large coercive force. Hexagonal ferrite is a typical hard ferrite.

Garnet ferrite has a garnet-type crystal structure. The composition formula of garnet ferrite is represented by RFe ₅ O ₁₂ (R is a rare earth element). Garnet ferrite is also called Rare-earth Iron Garnet (RIG). A typical example of garnet ferrite is yttrium iron garnet (YIG). Garnet ferrite has a small magnetic loss at high frequencies.

When the magnetic filler 2 further contains the ferrite 23, the average particle size of the ferrite 23 is preferably smaller than the average particle size of the second iron-nickel alloy filler 22. Specifically, the average particle size of the ferrite 23 is preferably 0.05 μm or more and 5 μm or less, and more preferably 0.1 μm or more and less than 3.5 μm. Thereby, the gap between the particles of the first iron-nickel alloy filler 21 and the second iron-nickel alloy filler 22 can be filled with the ferrite 23 (see FIG. 2). If there is a gap between the particles of the first iron-nickel alloy filler 21 and the second iron-nickel alloy filler 22, a demagnetizing field may occur in the gap. This demagnetic field can cause a decrease in magnetic permeability, but if the above gap is filled with ferrite 23 as much as possible, the magnetic permeability at high frequencies can be further increased.

The average particle size of the ferrite 23 is preferably 0.03 times or more and 0.5 times or less, and 0.04 times or more and less than 0.3 times the average particle size of the second iron-nickel alloy filler 22. Is more preferable. This makes it possible to increase the filling of the magnetic filler 2.

When the magnetic filler 2 further contains the ferrite 23, the ferrite 23 preferably contains spherical particles. This makes it possible to increase the filling of the ferrite 23. That is, when the ferrite 23 contains spherical particles, the filling amount of the ferrite 23 in the magnetic filler 2 can be increased as compared with the case where the ferrite 23 does not contain spherical particles. The ferrite 23 may contain particles having a shape other than the spherical shape. The shape other than the spherical shape is not particularly limited, and examples thereof include an ellipsoidal shape, a flat shape, a crushed shape, and an indefinite shape.

As described above, when the ferrite 23 is highly filled, the magnetic permeability of the molded product can be increased. Further, the fluidity of the magnetic resin composition 1 can be improved. That is, it becomes easy to mold the molded body.

When the magnetic filler 2 further contains the ferrite 23, the content of the ferrite 23 is preferably 0.1 part by mass or more and 35 parts by mass or less, more preferably 1 part by mass or more, based on 100 parts by mass of the total of the magnetic filler 2. It is 20 parts by mass or less. When the content of ferrite 23 is 0.1 part by mass or more, the magnetic permeability at high frequencies can be further increased. When the ferrite content is 35 parts by mass or less, the thickening of the magnetic resin composition 1 can be suppressed.

Preferably, the magnetic resin composition 1 does not substantially contain sendust and an amorphous alloy (amorphous alloy). Here, sendust is a ternary alloy (Fe—Si—Al alloy) composed of iron, silicon, and aluminum. The basic composition of sendust is Fe-10Si-5Al. On the other hand, the amorphous alloy is an alloy in which the arrangement of elements is not regular and disordered. As described above, if the magnetic resin composition 1 does not substantially contain sendust and an amorphous alloy, deterioration of chemical resistance and machinability can be suppressed. However, at least one of sendust and an amorphous alloy may be contained in the magnetic resin composition 1 as an unavoidable impurity.

[Non-magnetic filler]
The non-magnetic filler is not particularly limited, and examples thereof include silica powder and alumina powder.

The silica powder may contain crystalline silica particles, amorphous silica particles, and the like.

The alumina powder may contain α-alumina particles, γ-alumina particles, δ-alumina particles, θ-alumina particles, η-alumina particles, κ-alumina particles and the like.

≪Resin material≫
The resin material 3 contains, for example, a thermosetting resin, a curing agent, a curing accelerator, a surface treatment agent, and the like. Preferably, the resin material 3 contains a self-polymerizing material. As a result, the pot life (pot life) of the magnetic resin composition 1 can be lengthened. Further, by heat curing for a short time, a molded product having a high glass transition temperature (Tg) can be obtained.

[Thermosetting resin]
The thermosetting resin is not particularly limited, and is, for example, a bisphenol F type epoxy resin, a polyfunctional epoxy resin (for example, a trifunctional epoxy resin), a reactive diluent, an alicyclic epoxy resin, a bisphenol A type epoxy resin, and the like. Can be mentioned. Reactive diluents include alkyl diglycidyl ethers, alkyl monoglycidyl ethers, alkylphenol monoglycidyl ethers and the like.

Preferably, the thermosetting resin is liquid. When the thermosetting resin is liquid, it is easy to make the magnetic resin composition 1 into a paste. The reactive diluent is effective in reducing the viscosity of the magnetic resin composition 1.

When the thermosetting resin contains an epoxy resin, the epoxy equivalent of the epoxy resin is not particularly limited, but is, for example, 90 g / eq or more and 200 g / eq or less.

[Curing agent]
The curing agent is not particularly limited, and examples thereof include acid anhydrides, phenols, polyamines, polyamides, and imidazole compounds. Acid anhydrides include methylbicyclo [2.2.1] heptane-2,3-dicarboxylic acid anhydride and bicyclo [2.2.1] heptane-2,3-dicarboxylic acid anhydride. Preferably, the curing agent is liquid. When the curing agent is liquid, the magnetic resin composition 1 can be easily made into a paste. When the curing agent contains acid anhydrides, the acid anhydride equivalent of the acid anhydrides is, for example, 170 g / eq or more and 190 g / eq or less. The imidazole compound is effective for storage stability and low viscosity of the magnetic resin composition 1. In addition, some curing agents can function as a curing accelerator.

[Curing accelerator]
The curing accelerator is not particularly limited, and examples thereof include an imidazole compound and the like. Preferably, the curing accelerator is encapsulated. If the curing accelerator is encapsulated, the storage stability of the magnetic resin composition 1 can be improved. Further, by changing the film thickness of the capsule, the curing start temperature of the magnetic resin composition 1 can be controlled, and the curing behavior can be adjusted according to the usage pattern. For example, if the film thickness of the capsule is reduced, the reaction can be started at a low temperature. On the other hand, if the film thickness of the capsule is increased, the reaction can be started at a high temperature and the storage stability at a low temperature and a normal temperature can be improved. In addition, some curing accelerators may function as a curing agent.

[Surface treatment agent]
Surface treatment agents are used to form an interface between a filler surface with different chemical properties and a resin material. The surface treatment agent is not particularly limited, and examples thereof include a silane coupling agent and a dispersant. The silane coupling agent and the dispersant can improve the dispersibility of the filler in the magnetic resin composition 1.

≪Solvent≫
The solvent is not particularly limited, and examples thereof include methyl ethyl ketone (MEK), N, N-dimethylformamide (DMF), acetone, and methyl isobutyl ketone (MIBK).

≪Form≫
Preferably, the magnetic resin composition 1 is in the form of a liquid, a sheet, or a powder. This makes it possible to expand the applications.

<Molded body>
The molded product according to the present embodiment contains a cured product of the magnetic resin composition 1. Therefore, the molded product has high chemical resistance, and its magnetic properties are unlikely to deteriorate even when exposed to chemicals.

When the resin material 3 contains a thermosetting resin, the molded product is obtained by heat-curing the magnetic resin composition 1. The molded product has the following magnetic properties.

That is, the real part (μ') of the complex magnetic permeability of the molded product at 10 MHz is preferably 10 or more, more preferably 13 or more, still more preferably 17 or more. This makes it possible to further increase the magnetic permeability at high frequencies.

The loss coefficient (tan δ) of the molded product at 10 MHz is preferably 0.1 or less, more preferably 0.09 or less, and further preferably 0.08. This makes it possible to further reduce the loss.

The molded body can form a part of an insulating substrate used for manufacturing a printed wiring board. Even if the insulating substrate is treated with chemicals, the chemical resistance of the molded product is high, so that the magnetic properties of the molded product can be maintained. Therefore, it is possible to impart the magnetic characteristics of the molded product to the printed wiring board.

Further, the molded body may be used for manufacturing an inductor component. The inductor component includes a coiled wiring and an insulating layer covering the coiled wiring. The insulating layer is the above-mentioned molded product. This makes it easier for the inductor component to control noise in the high frequency band. Inductor components include coils, inductors, filters, reactors, and transformers. The use of the inductor component is not particularly limited, and examples thereof include a noise filter component and an impedance matching circuit component. Examples of the noise filter include a low-pass filter and a common choke coil.

3. 3. Aspects As will be clear from the above embodiments, the present disclosure includes the following aspects. In the following, the reference numerals are given in parentheses only to clearly indicate the correspondence with the embodiment.

The first aspect is the magnetic resin composition (1), which contains a magnetic filler (2) and a resin material (3). The magnetic filler (2) includes a first iron-nickel alloy filler (21) and a second iron-nickel alloy filler (22). The second iron-nickel alloy filler (22) has an average particle diameter smaller than the average particle diameter of the first iron-nickel alloy filler (21). The nickel content is more than 39% by mass with respect to the total mass of each of the first iron-nickel alloy filler (21) and the second iron-nickel alloy filler (22).

According to this aspect, a molded product having high chemical resistance can be obtained.

The second aspect is the magnetic resin composition (1) based on the first aspect. In the second aspect, the content of the magnetic filler (2) is less than 90% by volume with respect to the total volume of the magnetic resin composition (1).

According to this aspect, thickening can be suppressed and deterioration of vacuum print filling property can be suppressed. Moreover, the machinability can be improved. In addition, the magnetic loss at high frequencies can be reduced.

The third aspect is the magnetic resin composition (1) based on the first or second aspect. In the third aspect, the average particle size of the second iron-nickel alloy filler (22) is more than 1 μm.

According to this aspect, thickening can be suppressed and deterioration of vacuum print filling property can be suppressed.

The fourth aspect is the magnetic resin composition (1) based on any one of the first to third aspects. In the fourth aspect, the average particle size of the first iron-nickel alloy filler (21) is less than 24 μm.

According to this aspect, machinability can be improved. In addition, the magnetic loss at high frequencies can be reduced.

A fifth aspect is the magnetic resin composition (1) based on any one of the first to fourth aspects. In a fifth aspect, the magnetic filler (2) further comprises a ferrite (23).

According to this aspect, the magnetic permeability at high frequencies can be increased.

The sixth aspect is the magnetic resin composition (1) based on the fifth aspect. In the sixth aspect, the average particle size of the ferrite (23) is smaller than the average particle size of the second iron-nickel alloy filler (22).

According to this aspect, the gap between the particles of the first iron-nickel alloy filler (21) and the second iron-nickel alloy filler (22) can be filled with the ferrite (23). This makes it possible to further increase the magnetic permeability at high frequencies.

A seventh aspect is the magnetic resin composition (1) based on any one of the first to sixth aspects. In the seventh aspect, the resin material (3) contains a self-polymerizing material.

According to this aspect, the pot life (pot life) can be lengthened. Further, by heat curing for a short time, a molded product having a high glass transition temperature (Tg) can be obtained.

The eighth aspect is a molded product and includes a cured product of the magnetic resin composition (1) based on any one of the first to seventh aspects.

According to this aspect, a molded product having high chemical resistance can be obtained.

The ninth aspect is a molded body based on the eighth aspect. In the ninth aspect, the real part (μ') of the complex magnetic permeability of the molded product at 10 MHz is 10 or more.

According to this aspect, the magnetic permeability at high frequencies can be further increased.

The tenth aspect is a molded product based on the eighth or ninth aspect. In the tenth aspect, the loss coefficient (tan δ) of the molded product at 10 MHz is 0.1 or less.

According to this aspect, it is possible to reduce the loss.

Hereinafter, the present disclosure will be specifically described with reference to Examples. However, the present disclosure is not limited to the examples.

A paste-like magnetic resin composition (hereinafter, also referred to as “magnetic paste”) was prepared. The raw materials for the magnetic paste are shown below.

≪Magnetic filler≫
[Fe-Ni alloy]
Fe-50Ni (1) (nickel content: 50% by mass, average particle diameter: 3 μm, particle shape: spherical, insulating layer: yes)
Fe-50Ni (2) (nickel content: 50% by mass, average particle diameter: 5 μm, particle shape: spherical, insulating layer: yes)
Fe-50Ni (3) (nickel content: 50% by mass, average particle diameter: 6 μm, particle shape: spherical, insulating layer: yes)
Fe-50Ni (4) (nickel content: 50% by mass, average particle diameter: 10 μm, particle shape: spherical, insulating layer: yes)
Fe-50Ni (5) (nickel content: 50% by mass, average particle diameter: 20 μm, particle shape: spherical, insulating layer: yes)
Fe-50Ni (6) (nickel content: 50% by mass, average particle diameter: 24 μm, particle shape: spherical, insulating layer: yes)
Fe-50Ni (7) (nickel content: 50% by mass, average particle diameter: 1 μm, particle shape: spherical, insulating layer: yes)
Fe-50Ni (8) (nickel content: 50% by mass, average particle diameter: 1.5 μm, particle shape: spherical, insulating layer: yes)
Fe-50Ni (9) (nickel content: 50% by mass, average particle diameter: 8 μm, particle shape: spherical, insulating layer: yes)
[Ferrite]
・ Magnetite (average particle size: 0.3 μm)
-Mn ferrite (1) (average particle size: 3.5 μm)
-Mn ferrite (2) (average particle size: 0.3 μm)
〔others〕
-Sendust, Fe-10Si-5Al (silicon content: 10% by mass, aluminum content: 5% by mass, average particle size: 10 μm)
-Fe amorphous alloy, Fe-Si-Cr-B (average particle size: 10 μm)
≪Resin material≫
[Thermosetting resin]
-Bisphenol F type epoxy resin (manufactured by Nittetsu Chemical & Materials Co., Ltd., trade name "YDF-8170C", liquid, epoxy equivalent: 155 to 165 g / eq)
-Alicyclic epoxy resin (manufactured by Daicel Co., Ltd., trade name "Selokiside 2021P", liquid, epoxy equivalent: 128-145 g / eq)
-Trifunctional epoxy resin (manufactured by ADEKA Corporation, trade name "EP-3950S", glycidylamine type, epoxy equivalent: 95 g / eq)
-Reactive diluent (manufactured by Mitsubishi Chemical Corporation, trade name "YED216D", liquid, epoxy equivalent: 110-130 g / eq)
[Curing agent]
-Epoxy resin curing agent (manufactured by Shin Nihon Rika Co., Ltd., trade name "Ricacid HNA-100", acid anhydride, acid anhydride equivalent: 174 to 184 g / eq)
-Imidazole-based epoxy resin curing agent (manufactured by Shikoku Chemicals Corporation, trade name "2MAOK-PW", fine powder)
[Curing accelerator]
-Epoxy resin latent curing agent (manufactured by Asahi Kasei Corporation, trade name "NovaCure HX-3722", capsule-type latent curing agent)
[Surface treatment agent]
・ Silane coupling agent (manufactured by Momentive Performance Materials Japan GK, trade name "Silquest A-187")
・ Dispersant (manufactured by Big Chemie Japan Co., Ltd., product name "DISPERBYK-2152")
<Magnetic paste>
The above raw materials were blended so as to have the contents shown in Tables 1 to 5, and uniformly mixed to obtain a magnetic paste. A known mixer was used for mixing the raw materials.

<Evaluation>
The above magnetic paste was tested for the following evaluation items.

[viscosity]
The viscosity of the magnetic paste was measured using a rheometer "AR2000ex" manufactured by TA Instruments. Specifically, the gap between the upper and lower parallel plates having a diameter of 25 mm is set to 300 μm, and after filling this gap with magnetic paste, a temperature equilibrium time of 2 minutes is allowed at room temperature, and the rotation speed is set to 2.0 rpm. The viscosity was measured.

[Chixo index]
In the same manner as the above viscosity measurement, the viscosity of the magnetic paste was measured at a rotation speed of 0.2 rpm. The chixo index of the magnetic paste was calculated by the following formula using the viscosity at a rotation speed of 0.2 rpm and the viscosity at a rotation speed of 2.0 rpm.

Chixo index = Viscosity at 0.2 rpm / Viscosity at 2.0 rpm.

[Vacuum print filling property]
First, a test substrate (manufactured by Panasonic Corporation, trade name "R-1515V", thickness 1.0 mm) was drilled to form 100 through holes. The inner diameter of each through hole is 0.35 mm, and the pitch between the through holes is 1.0 mm.

Next, in order to fill the through holes of the test substrate with the magnetic paste, vacuum printing was performed by a screen printing method using a screen plate. The screen plate has a through hole with an inner diameter of 0.5 mm at a position corresponding to each through hole of the test substrate. The conditions for vacuum printing are a vacuum degree of 100 Pa, a squeegee angle of 10 °, and a squeegee speed of 8 mm / sec. The magnetic paste after vacuum printing was first cured by step curing at 100 ° C. for 1 hour and then at 150 ° C. for 1 hour.

Then, the test substrate was cut and the cross section of each through hole was observed, and normal through holes were counted. Here, the normal through hole is a through hole that is not unfilled and does not contain air bubbles having a size of 50 μm or more in the cured product of the filled magnetic paste. Then, the vacuum print filling property was determined according to the following criteria.

S: 90 or more and 100 or less normal through holes A: 70 or more and less than 90 normal through holes B: 70 or less normal through holes.

[chemical resistance]
The magnetic paste was heat-cured in the atmosphere to obtain a cured product. The heating conditions are 100 ° C. for 1 hour and then 150 ° C. for 1 hour. Further, the entire surface of the cured product was polished with No. 1500 abrasive paper so that the filler was exposed to obtain an evaluation molded product (40 mm × 40 mm × thickness 0.5 mmt).

On the other hand, a desmear treatment solution (300 mL) was placed in a beaker. The desmear treatment liquid contains 100 mL / L of "Reduction Securigant P500" manufactured by Atotech and 50 mL / L of a 98% aqueous sulfuric acid solution.

Then, the evaluation molded product was immersed in the desmear treatment liquid in the beaker, and the presence or absence of foaming on the surface of the evaluation molded product was confirmed over time. Judgment was made according to the following criteria.

S: No foaming on the surface of the evaluation molded product is confirmed even after immersion for 20 minutes A: No foaming is confirmed on the surface of the evaluation molded product even after immersion for 10 minutes B: For evaluation after immersion for less than 10 minutes Foaming on the surface of the molded product is confirmed.

[Hole workability]
The magnetic paste was heat-cured in the atmosphere to obtain an evaluation molded product (100 mm × 100 mm × thickness 1.0 mmt). The heating conditions are 100 ° C. for 1 hour and then 150 ° C. for 1 hour.

Next, 3000 through holes were formed in the evaluation molded product using "ND-1S211" manufactured by Via Mechanics. Specifically, while rotating the drill bit (Φ0.15 mm) at a speed of 80 kHz, drilling was performed at a feed rate of 0.8 m / min and a pitch of 1.0 mm.

Then, by comparing the photographs from the front of the drill bit before and after the drilling of 3000 through holes, the area ratio of the drill bit scraped by the wear caused by the drilling is calculated, and this is the drill bit wear rate. It was set to (%). Judgment was made according to the following criteria.

S: Drill bit wear rate is less than 20% A: Drill bit wear rate is 20% or more and less than 40% B: Drill bit wear rate is 40% or more.

[Magnetic characteristics]
The magnetic paste was heat-cured in the atmosphere to obtain a ring-shaped evaluation molded product (outer diameter 7.0 mm, inner diameter 3.5 mm, thickness 1.0 mmt). The heating conditions are 100 ° C. for 1 hour and then 150 ° C. for 1 hour.

Next, the complex magnetic permeability of the ring-shaped evaluation molded product at 10 MHz was measured using a “4291A RF impedance / material analyzer” manufactured by Hewlett-Packard Company. The measurement was performed at room temperature with the current frequency set to 1 MHz or more and 500 MHz or less. From the initial magnetization curve obtained by measurement, the real part (μ') and the imaginary part (μ ”) were obtained, and the magnetic permeability (complex magnetic permeability ( _μr )) and the loss coefficient (tan δ) were calculated from these. ..

1 Magnetic resin composition 2 Magnetic filler 21 First iron-nickel alloy filler 22 Second iron-nickel alloy filler 23 Ferrite 3 Resin material

Claims (10)

Contains a magnetic filler and a resin material,
The magnetic filler includes a first iron-nickel alloy filler and a second iron-nickel alloy filler having an average particle size smaller than the average particle size of the first iron-nickel alloy filler.
The nickel content is more than 39% by mass with respect to the total mass of each of the first iron-nickel alloy filler and the second iron-nickel alloy filler.
Magnetic resin composition. The content of the magnetic filler is less than 90% by volume with respect to the total volume of the magnetic resin composition.
The magnetic resin composition according to claim 1. The average particle size of the second iron-nickel alloy filler is more than 1 μm.
The magnetic resin composition according to claim 1 or 2. The average particle size of the first iron-nickel alloy filler is less than 24 μm.
The magnetic resin composition according to any one of claims 1 to 3. The magnetic filler further comprises ferrite.
The magnetic resin composition according to any one of claims 1 to 4. The average particle size of the ferrite is smaller than the average particle size of the second iron-nickel alloy filler.
The magnetic resin composition according to claim 5. The resin material comprises a self-polymerizing material.
The magnetic resin composition according to any one of claims 1 to 6. A cured product of the magnetic resin composition according to any one of claims 1 to 7.
Molded body. The real part (μ') of the complex magnetic permeability at 10 MHz of the molded product is 10 or more.
The molded product according to claim 8. The loss coefficient (tan δ) of the molded product at 10 MHz is 0.1 or less.
The molded product according to claim 8 or 9.

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