magnetic complex

Abstract

The present invention provides a magnetic composite having a ferrite layer that is dense, has a relatively thick film, has excellent magnetic and electrical properties, and has better adhesion. The magnetic composite comprises a resin substrate and a ferrite layer provided on the surface of the resin substrate, wherein the resin substrate has a thickness (dR) of 10 μm or more, the ferrite layer has a thickness (dF) of 2.0 μm or more, is composed mainly of spinel-type ferrite, and in X-ray diffraction analysis, the ratio (I222 / I311) of the integrated intensity of the (222) plane to the integrated intensity (I311) of the (311) plane is 0.00 or more and 0.03 or less.

Description

Technology Field

[0001] The present invention relates to a magnetic composite. Background Technology

[0002] With the rapid advancement of electronic information and communication technology in recent years, the use of electromagnetic waves has increased rapidly, and the frequency and broadband of the electromagnetic waves used are becoming more advanced. Specifically, in addition to systems in the quasi-microwave band, such as mobile phones (1.5, 2.0 GHz) and wireless LANs (2.45 GHz), new systems using radio waves in the millimeter wave band, such as high-speed wireless LANs (65 GHz) and collision avoidance radars (76.5 GHz), are being introduced.

[0003] With the expansion of electromagnetic wave usage and the advancement of high frequencies, issues related to electromagnetic interference—such as malfunctions in electronic devices caused by electronic noise and adverse effects on the human body—are emerging, leading to a growing demand for EMC countermeasures. As one means of EMC countermeasures, a method is known to prevent the intrusion of unwanted electromagnetic waves by utilizing electromagnetic wave absorbers.

[0004] Materials exhibiting conductive loss, dielectric loss, and / or magnetic loss are used as electromagnetic wave absorbers. Ferrites, which have high permeability and high electrical resistance, are widely used as materials exhibiting magnetic loss. Ferrites undergo a resonance phenomenon at specific frequencies to absorb electromagnetic waves and convert the absorbed electromagnetic energy into thermal energy, which is then radiated outwards. As electromagnetic wave absorbers utilizing ferrite, composite materials containing ferrite powder and binder resin, or ferrite thin films, have been proposed. Furthermore, for applications other than electromagnetic wave absorbers, a technique for forming a ferrite film on a substrate is known.

[0005] For example, Patent Document 1 discloses an electromagnetic wave absorber characterized by being formed by physically depositing a ferromagnetic material onto a gaseous phase composed of an organic polymer, and states that the electromagnetic wave absorber has good electromagnetic wave absorption characteristics, is small and lightweight, flexible, and rigid (Claim 1 and Paragraph

[0008] ). Furthermore, Patent Document 1 describes that oxide-based soft magnetic materials are mainly used as ferromagnetic materials, that ferrite is preferred as oxide-based soft magnetic materials, and that physical vapor deposition methods include EB deposition, ion plating, magnetron sputtering, and counter-target type magnetron sputtering (Paragraphs

[0009] ,

[0010] and

[0017] ).

[0006] Patent Document 2 discloses a composite structure of a resin and a brittle material, characterized in that an underlayer made of an adhesive material that adheres to the surface of a resin substrate is formed, and a layer of a polycrystalline brittle material such as ferrite is formed on all or part of the underlayer (Claim 1). In addition, Patent Document 2 describes attempting to form a structure by spraying submicron-sized ferrite particles with a purity of 99% or more onto a plastic substrate using a fine particle beam deposition method, investigating the electromagnetic wave absorption effect, and stably composited on a resin substrate even with a brittle material such as ferrite (Paragraphs

[0036] and

[0055] to

[0059] ).

[0007] Patent Document 3 discloses the manufacture of a radio wave absorber using the AD method or the ferrite plating method (paragraphs

[0020] –

[0022] ). Specifically, the composition of the ferrite substrate is Ni 0.5 Zn 0.5It is described that a ferrite raw material powder is mixed to become Fe2O4 and then mixed with a mixer and supplied to a nozzle, the pressure inside the chamber is adjusted to 7 Pa, and the aerosolized ferrite raw material powder is sprayed from the tip of the nozzle onto a substrate made of polyimide resin at a flow rate of 5 liters / min to produce a ferrite substrate with a film thickness of 5 μm, and 16 holes with a diameter of 2 μm are formed in the ferrite substrate by etching treatment to obtain an electromagnetic wave absorber (paragraph

[0020] ). Prior art literature

[0008] Japanese Patent Publication No. 2005-045193 Japanese Patent Publication No. 2006-175375 Japanese Patent Publication No. 2006-269675 The problem to be solved

[0009] As such, it is proposed to apply a composite fabricated by forming a ferrite-containing layer on a substrate to applications such as electromagnetic wave absorbers, but there was room for improvement in the prior art. For example, the electromagnetic wave absorber proposed in Patent Document 1 is formed by physical vapor deposition, but it is difficult to form a thick film during manufacturing, and there were limitations in improving magnetic properties such as electromagnetic wave absorption characteristics. Furthermore, even if a thick film could be formed, there was a problem that the film was prone to peeling off from the substrate. The composite structure of Patent Document 2 requires forming an underlayer on the surface of the substrate in advance using an adhesive material to fabricate it. Since this underlayer has poor heat resistance, there is a problem of insufficient thermal stability of the composite structure. In addition, there is a problem that manufacturing is difficult due to the complex manufacturing process. Furthermore, in the examples, fine brittle material particles are used as raw materials, and there is a problem that the density of the obtained brittle material layer is insufficient. Patent Document 3 does not disclose detailed manufacturing conditions such as the particle size of the ferrite raw material powder, and it is unclear to what extent the obtained electromagnetic wave absorber possesses density and characteristics.

[0010] The inventors have conducted a thorough examination in consideration of these problems. As a result, they found that in a magnetic composite comprising a resin substrate and a ferrite layer, the crystal state of the ferrite layer is important, and by controlling this, a ferrite layer can be obtained that is dense, has a relatively thick film, exhibits excellent magnetic and electrical properties, and has better adhesion.

[0011] The present invention is completed based on such findings and aims to provide a magnetic composite having a ferrite layer that is dense, has a relatively thick film, excellent magnetic and electrical properties, and has even better adhesion. means of solving the problem

[0012] The present invention includes the following embodiments (1) to (7). Meanwhile, in this specification, the expression “~” includes the numerical values ​​at both ends. That is, “X~Y” has the same meaning as “X or greater and Y or less.”

[0013] (1) A magnetic composite having a resin substrate and a ferrite layer provided on the surface of the resin substrate,

[0014] The above resin substrate has a thickness (d R ) is 10μm or larger, and

[0015] The above ferrite layer has a thickness (d F ) is 2.0 μm or greater, consists mainly of spinel-type ferrite, and in X-ray diffraction analysis the integrated intensity (I of the (311) plane) 311 Integral strength (I) of the (222) plane for ) 222 The ratio of )(I 222 / I 311 A magnetic composite having ) 0.00 or more and 0.03 or less.

[0016] (2) The magnetic composite of (1), wherein the ferrite layer has an α-Fe2O3 content of 0.0 mass% or more and 20.0 mass% or less.

[0017] (3) The ferrite layer comprises iron (Fe) and oxygen (O), and further comprises at least one element selected from the group consisting of lithium (Li), magnesium (Mg), aluminum (Al), titanium (Ti), manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu) and cobalt (Co), the magnetic composite of (1) or (2).

[0018] (4) The above ferrite layer has a thickness (d F The ratio of surface arithmetic mean height (Sa) to ) (Sa / d F A magnetic composite of any one of (1) to (3) above, wherein ) is greater than 0.00 and less than or equal to 0.20.

[0019] (5) The ferrite layer comprises a ferrite component, and the remainder has a composition of unavoidable impurities, any one of (1) to (4) magnetic composite.

[0020] (6) The specific gravity of the resin constituting the resin substrate is 0.95 g / cm³ 3 A magnetic composite of any one of the above (1) to (5).

[0021] (7) The resin constituting the resin substrate is at least one selected from the group consisting of polycarbonate (PC), polyimide (PI), polyvinyl chloride (PVC), polyoxymethylene (POM), acrylonitrile butadiene styrene (ABS), polyetheretherketone (PEEK) and polyamide (PA), and is a magnetic composite of any one of (1) to (6). Effects of the invention

[0022] According to the present invention, a magnetic composite is provided having a ferrite layer that is dense, has a relatively thick film, has excellent magnetic and electrical properties, and has good adhesion. Brief explanation of the drawing

[0023] Figure 1 shows one embodiment of a magnetic composite. Figure 2 shows another embodiment of the magnetic composite. Figure 3 shows another embodiment of the magnetic composite. Figure 4 shows another embodiment of the magnetic composite. Figure 5 shows an example of applying a magnetic composite to an inductor. Figure 6 shows another example of applying a magnetic composite to an inductor. Figure 7 shows another example of applying a magnetic composite to an inductor. Figure 8 shows an example of applying a magnetic composite to an antenna element (UHF-ID tag). Figure 9 shows an example of the configuration of an aerosol deposition film device. Figure 10 shows the cross-sectional elemental mapping of the ferrite layer. Figure 11 shows the permeability of the magnetic complex (real part μ', imaginary part μ"). Specific details for implementing the invention

[0024] Specific embodiments of the present invention (hereinafter referred to as "the present embodiments") will be described. Meanwhile, the present invention is not limited to the following embodiments, and various modifications are possible within the scope of not altering the gist of the present invention.

[0025] <<1. Magnetic Complex>>

[0026] The magnetic composite of the present embodiment comprises a resin substrate and a ferrite layer provided on the resin substrate. The resin substrate has a thickness (d R ) is 10μm or more. The thickness of the ferrite layer (d F ) is 2.0 μm or more. In addition, the ferrite layer is mainly composed of spinel-type ferrite, and in X-ray diffraction analysis, the integrated intensity (I of the (311) plane) 311 Integral strength (I) of the (222) plane for ) 222 The ratio of )(I 222 / I 311 ) is 0.00 or greater and 0.03 or less. The magnetic composite is described in detail below.

[0027] The resin constituting the resin substrate is not particularly limited. It may be a single resin, or a mixture or copolymer of two or more types of resins. Preferably, the resin is at least one selected from the group consisting of polycarbonate (PC), polyimide (PI), polyvinyl chloride (PVC), polyoxymethylene (POM), acrylonitrile butadiene styrene (ABS), polyetheretherketone (PEEK), and polyamide (PA). These resins have excellent mechanical strength and excellent insulation properties.

[0028] The specific gravity of the resin constituting the resin substrate is 0.95 g / cm³ 3 It is desirable that it be above this level. Specific gravity is 0.95 g / cm³ 3 In smaller cases, the collision energy is easily dispersed when raw material particles collide with the substrate during film deposition, making it difficult for plastic deformation of the particles to occur. Consequently, the formation of the ferrite layer becomes difficult.

[0029] The color tone of the resin substrate is not limited. For example, colorless, transparent, or light-colored resins may be used. Additionally, resins colored to the extent that light is transmitted may be used. In magnetic composites fabricated using such resins as substrates, the ferrite layer can be seen through the resin when viewed from the side where the ferrite layer is not formed. Therefore, along with various characteristics such as electromagnetic shielding performance, it becomes possible to impart to the composite an aesthetic appeal that cannot be obtained when using resins that do not transmit light.

[0030] The shape of the resin substrate is not limited. The substrate may be in the shape of a sheet, or it may have a shape other than a sheet. For example, a resin substrate having a complex three-dimensional shape may be used. When such a resin substrate having a complex shape is applied to a housing light body of an electrical circuit, a light body with excellent mechanical strength can be obtained. In addition, a ferrite layer may be provided on the entire surface of the resin substrate, or a ferrite layer may be provided on a part of it. For example, a ferrite layer may be provided on a part of the surface of the resin substrate using a resin substrate with a complex shape. Accordingly, electromagnetic shielding performance can be imparted to any surface of the housing light body with a complex shape. Conventionally, to impart electromagnetic shielding performance to a resin substrate with a complex shape, it was necessary to punch-form a sheet-shaped resin substrate and attach a ferrite sheet to the punched member. By using the magnetic composite of the present embodiment, such work is unnecessary, so a light body having various characteristics such as electromagnetic shielding performance can be manufactured at a low cost. In addition, unlike electromagnetic shielding materials composed of an integrated mixture of resin and filler, the resin substrate and the ferrite layer are clearly separated, so it is possible to achieve design properties that could not be obtained in the past.

[0031] Thickness of the resin substrate (d RThe thickness is limited to 10 μm or more (0.01 mm or more). If the resin substrate is excessively thin, it is difficult to produce a composite with sufficient mechanical strength. If flexibility is desired, the thickness of the resin substrate is preferably 25 μm or more (0.025 mm or more), and more preferably 35 μm or more (0.035 mm or more). If the thickness of the ferrite layer is desired to be large, 35 μm or more (0.035 mm or more) is more preferably, and 100 μm or more (0.1 mm or more) is particularly preferably. The thickness may be 5,000 μm or more (5 mm or more). Meanwhile, there is no upper limit to the thickness. However, flexibility can be imparted to the magnetic composite by appropriately thinning the resin substrate. The thickness may be 100,000 μm or less (100 mm or less), 50,000 μm or less (50 mm or less), 10,000 μm or less (10 mm or less), 5,000 μm or less (5 mm or less), and 1,000 μm or less (1 mm or less).

[0032] In addition, the resin substrate may be in the shape of a plate or a sheet. However, it is preferably in the shape of a sheet. By using a sheet-shaped resin substrate (resin sheet), a magnetic composite with excellent flexibility can be produced. In addition, the resin substrate may be composed solely of resin, or it may be a laminate of a non-resin substrate and a resin layer. In this case, the resin layer laminated on the non-resin substrate corresponds to the resin substrate. A metal film, etc., may be used as the non-resin substrate.

[0033] Meanwhile, in the case where the substrate is a laminate composed of multiple layers, the thickness of the layer in direct contact with the ferrite layer corresponds to the thickness of the substrate. In the case where the substrate has irregularities, the arithmetic mean of the thinnest and thickest parts of the substrate where the ferrite layer is formed is the thickness of the substrate (d R ) and the arithmetic mean of the thinnest and thickest parts of the composite and the thickness of the substrate (d R) difference in the thickness of the ferrite layer (d F ...is used. In cases where ferrite layers are formed on both sides of the composite, the arithmetic mean of the thinnest and thickest parts of the composite and the thickness of the substrate (d R ) The difference is considered to be twice the thickness of the ferrite layer, and the thickness (d F Calculates ). That is, in the case where ferrite layers of the same film thickness are formed on both sides of the substrate, the thickness of the ferrite layer on one side is d F Equivalent to. Thickness of the substrate (d R If ) exceeds 2,000μm, the thickness of the substrate (d R Assuming ) is 2,000 μm, the thickness ratio (d F / d R Produces ).

[0034] The ferrite layer of the present embodiment is a polycrystalline material with spinel-type ferrite as the main component. That is, it is an aggregate of crystal grains composed of spinel-type ferrite. Spinel-type ferrite is a complex oxide of iron (Fe) having a spinel-type crystal structure, and most of it exhibits soft magnetism. By providing a layer with spinel-type ferrite as the main component, the magnetic properties of the magnetic composite are improved. The type of spinel-type ferrite is not particularly limited. For example, at least one type selected from the group consisting of manganese (Mn)-based ferrite, manganese-zinc (MnZn)-based ferrite, magnesium (Mg)-based ferrite, magnesium-zinc (MgZn)-based ferrite, nickel (Ni)-based ferrite, nickel-copper (NiCu)-based ferrite, nickel-copper-zinc (NiCuZn)-based ferrite, cobalt (Co)-based ferrite, and cobalt-zinc (CoZn)-based ferrite may be cited. In addition, it may be a mixture of multiple types of ferrite and / or a solid solution. Meanwhile, in this specification, the term "main component" refers to a component with a content of 50.0 mass% or more. In order to utilize the excellent magnetic properties of spinel-type ferrite, the content ratio of spinel-type ferrite (ferrite phase) in the ferrite layer is preferably 60.0 mass% or more, more preferably 70.0 mass% or more, even more preferably 80.0 mass% or more, and particularly preferably 90.0 mass% or more.

[0035] The thickness (d) of the ferrite layer of this embodiment FThe thickness is limited to 2.0 μm or more. If the ferrite layer is excessively thin, the film thickness of the ferrite layer becomes non-uniform, and there is a risk that magnetic properties and electrical properties (electrical insulation) will deteriorate. A thickness of 3.0 μm or more is preferred, and 3.5 μm or more is more preferred. The thickness may be 5.0 μm or more, 6.0 μm or more, or 7.0 μm or more. There is no upper limit to the thickness. However, it is difficult to form an excessively thick ferrite layer while maintaining density. In addition, if the ferrite layer is excessively thick, the internal stress of the ferrite layer becomes too high, and there is a risk that the ferrite layer will delaminate. Furthermore, when imparting flexibility to the magnetic composite, it is preferable that the ferrite layer be appropriately thin. A thickness of 100.0 μm or less is preferred, 50.0 μm or less is more preferred, 20.0 μm or less is more preferred, and 10.0 μm or less is particularly preferred. In addition, it is desirable that the ferrite layer is in direct contact with the resin substrate, that is, that no other layer is interposed between the ferrite layer and the resin substrate.

[0036] The ferrite layer of the present embodiment has an integrated intensity (I) of the (311) plane in X-ray diffraction (XRD) analysis. 311 Integral strength (I) of the (222) plane for ) 222 The ratio of )(I 222 / I 311 ) is 0.00 or greater and 0.03 or less (0.00≤I 222 / I 311 (≤0.03). That is, when the ferrite layer is analyzed by X-ray diffraction, most diffraction peaks based on the (222) plane of the spinel are not observed in the X-ray diffraction profile. This is because the crystal grains constituting the ferrite layer are composed of microcrystalline particles. The crystal grains of the ferrite layer in this embodiment undergo plastic deformation during the manufacture of the magnetic composite. Therefore, the crystallite diameter is small and the distribution of the lattice constant is broad. As a result, the XRD peaks become broad, and the (222) diffraction peaks are not observed. I 222 / I 311The value is preferably 0.02 or less, more preferably 0.01 or less. In contrast, general spinel-type ferrite materials have high crystallinity even in a polycrystalline state. Because of this, the (222) plane diffraction peak is observed relatively strongly. Specifically, the XRD peak intensity ratio (I 222 / I 311 ) is about 0.04~0.05 (4~5%).

[0037] XRD peak intensity ratio (I 222 / I 311 The ferrite layer of the present embodiment, which has a small magnetic field, is characterized by being dense. This is because crystal grains that have undergone plastic deformation tend to be densely packed. Furthermore, the ferrite layer of the present embodiment has the effect of excellent adhesion to the resin substrate. This is because the contact area with the resin substrate has increased as the crystal grains undergo plastic deformation. Additionally, it is presumed that the bonding with the resin constituting the substrate becomes stronger due to the small crystallite diameter and the crystal structure with broken periodicity, which is another factor. Furthermore, the ferrite layer of the present embodiment is characterized by having low magnetic loss (tanδ) in the high-frequency region of 500 MHz or higher. This is presumed to be because the correlation length of the magnetic moment is shortened due to the small crystallite diameter, and as a result, domain wall movement in the high-frequency region occurs smoothly. In contrast, in general spinel-type ferrite materials, the correlation length of the magnetic moment is long. In the low-frequency region, domain wall movement by an external magnetic field is possible, but in the high-frequency region of 100 MHz or higher, domain wall movement cannot keep up with fluctuations in the external magnetic field, resulting in increased magnetic loss.

[0038] Preferably, the crystallite diameter of the ferrite layer is 1 nm or more and 10 nm or less. By making the crystallite diameter smaller than 10 nm, the density and adhesion of the ferrite layer are increased, and the effect of suppressing the increase in magnetic loss becomes more pronounced. In addition, by making the crystallite diameter 1 nm or more, it is possible to prevent the ferrite layer from becoming amorphous and the magnetic properties from deteriorating. More preferably, the crystallite diameter is 1 nm or more and 5 nm or less, more preferably 1 nm or more and 3 nm or less, and particularly preferably 1 nm or more and 2 nm or less.

[0039] Preferably, the lattice constant of the spinel-type ferrite included in the ferrite layer is 8.30 Å or more and 8.80 Å or less. By setting the lattice constant to 8.30 Å or more and 8.80 Å or less, the effect of increasing the magnetic properties of the raw material particles can be obtained. More preferably, the lattice constant is 8.30 Å or more and 8.60 Å or less, and even more preferably 8.30 Å or more and 8.50 Å or less.

[0040] Preferably, the thickness (d) of the resin substrate R Thickness of the ferrite layer (d) for ) F The ratio of )(d F / d R ) is between 0.0001 and 0.5000. Thickness ratio (d F / d R If ) is excessively small, the film thickness of the ferrite layer becomes non-uniform, leading to a deterioration in magnetic and electrical properties (electrical insulation). The ratio of thicknesses (d F / d R ) is more preferably 0.0010 or higher. Meanwhile, the thickness ratio (d F / d R If ) is excessively large, the resin substrate cannot resist the internal stress of the ferrite layer, and there is a risk that the resin composite will bend. The ratio of thicknesses (d F / d R) is more preferably 0.4000 or less, more preferably 0.3000 or less, and particularly preferably 0.2000 or less. Meanwhile, in the case of using a laminate of a non-resin substrate and a resin layer, the thickness of the resin layer corresponds to the thickness of the resin substrate.

[0041] Preferably, the ferrite layer contains α-Fe2O3 (hematite) in an amount of 0.0 mass% or more and 20.0 mass% or less. α-Fe2O3 is free iron oxide that has not formed a spinel phase. Unlike the spinel phase, which is a ferromagnetic material, α-Fe2O3 is an antiferromagnetic material and exhibits almost no magnetism externally. Therefore, if the amount of α-Fe2O3 is excessively high, there is a risk that the magnetic properties of the ferrite layer will deteriorate. The amount of α-Fe2O3 is more preferably 15.0 mass% or less, and more preferably 10.0 mass% or less. Meanwhile, α-Fe2O3 is a stable compound with high electrical resistance. By appropriately including α-Fe2O3 in the ferrite layer, the conductive paths within the ferrite layer can be severed, thereby allowing the electrical resistance to be further increased. In particular, manganese (Mn)-based ferrites and manganese-zinc (MnZn)-based ferrites tend to have low electrical resistance because they contain manganese (Mn) and iron (Fe) ions with unstable valence. Therefore, incorporating α-Fe2O3 into these ferrites can significantly enhance electrical resistance. Furthermore, appropriately incorporating α-Fe2O3 can improve the densification and adhesion of the ferrite layer. α-Fe2O3 is generated during the ferrite layer formation process in the manufacture of magnetic composites. Specifically, α-Fe2O3 is produced during the film deposition process through plastic deformation and reoxidation of ferrite crystal grains. This plastic deformation and reoxidation play a crucial role in increasing the densification and adhesion of the ferrite layer. Consequently, a ferrite layer containing an appropriate amount of α-Fe2O3 exhibits high density and adhesion. The amount of α-Fe2O3 is more preferably 0.1 mass% or more, more preferably 0.5 mass% or more, particularly preferably 1.0 mass% or more, and most preferably 5.0 mass% or more.

[0042] Preferably, the ferrite layer comprises iron (Fe) and oxygen (O), and also comprises at least one element selected from the group consisting of lithium (Li), magnesium (Mg), aluminum (Al), titanium (Ti), manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), and cobalt (Co).

[0043] Preferably, the ferrite layer has a thickness (d F The ratio of surface arithmetic mean height (Sa) to ) (Sa / d F ) greater than 0.00 and less than or equal to 0.20 (0.00<Sa / d F It is (≤0.20). Roughness ratio (Sa / d F If ) is excessively large, the film thickness of the ferrite layer tends to become uneven. Therefore, there is a risk that leakage current may occur due to the localized concentration of the electric field when high voltage is applied. Roughness ratio (Sa / d F ) is more preferably greater than 0.00 and less than or equal to 0.15, more preferably greater than 0.00 and less than or equal to 0.10, and particularly preferably greater than 0.00 and less than or equal to 0.05.

[0044] The ferrite layer of the present embodiment has a relatively high density. This is because, as a result of the ferrite crystal particles constituting the ferrite layer undergoing repeated plastic deformation, small crystallite diameters are deposited as the ferrite layer. The relative density of the ferrite layer (density of the ferrite layer / true specific gravity of the ferrite powder) is preferably 0.40 (40%) or higher, more preferably 0.60 (60%) or higher, even more preferably 0.70 (70%) or higher, even more preferably 0.80 (80%) or higher, particularly preferably 0.90 (90%) or higher, and most preferably 0.95 (95%) or higher. By increasing the density, the effects of improving the magnetic properties, electrical properties, and adhesion of the ferrite layer become more pronounced.

[0045] The ferrite layer of the present embodiment has a relatively high electrical resistance. This is because the high density of the ferrite layer results in less adsorption of conductive components, such as moisture, which are a factor in the degradation of electrical resistance. In addition, it is presumed that the small crystallite diameter of the ferrite crystal grains constituting the ferrite layer also has an influence. In fact, the volume resistivity of a general MnZn ferrite material is 10 3 It is approximately Ω·cm. In contrast, the ferrite layer of the present embodiment exhibits a higher resistance value, and the cause can be determined by the size of the crystallite diameter. Furthermore, by incorporating an appropriate amount of α-Fe2O3, the electrical resistance of the ferrite layer can be further increased. The surface resistance of the ferrite layer is preferably 10 4 Ω or more, more preferably 10 5 Ω or more, more preferably 10 6 It is greater than Ω. By increasing the surface resistance, the insulation of the ferrite layer can be improved, which allows problems such as eddy current generation to be suppressed when the magnetic composite is applied to a device.

[0046] The ferrite layer preferably comprises ferrite constituents, with the remainder consisting of unavoidable impurities. That is, it is desirable not to include organic or inorganic components other than the ferrite constituents in an amount exceeding that of unavoidable impurities. The ferrite layer of the present embodiment can be sufficiently dense without adding resin components such as binders or inorganic additive components such as sintering aids. By minimizing the content of non-magnetic materials, excellent magnetic properties based on ferrite can be fully utilized. Meanwhile, ferrite constituents are components that constitute the spinel-type ferrite, which is the main component. For example, when the ferrite layer has manganese zinc (MnZn) ferrite as the main component, the ferrite constituents are iron (Fe), manganese (Mn), zinc (Zn), and oxygen (O). When the ferrite layer has nickel copper zinc (NiCuZn) ferrite as the main component, the ferrite constituents are iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), and oxygen (O). In addition, unavoidable impurities are components that are inevitably incorporated during manufacturing, and their content is typically 1,000 ppm or less. In particular, it is desirable that the ferrite layer does not contain components other than oxides, especially resin components.

[0047] It is preferable that the magnetic composite is manufactured by a process comprising preparing a resin substrate and spinel-type ferrite powder having an average particle size (D50) of 2.5 μm or more and 10.0 μm or less (preparation process), and forming a film on the surface of the resin substrate using the aerosol deposition method with the ferrite powder (film formation process), wherein the ratio (LCf / LCp) of the spinel-type lattice constant (LCf) contained in the ferrite layer to the spinel-type ferrite powder containing spinel-type lattice constant (LCp) is 0.95 or more and 1.05 or less (0.95≤LCf / LCp≤1.05).

[0048] The shape of the magnetic composite is not particularly limited. As shown in FIG. 1, the ferrite layer (ferrite film) may be provided over the entire surface of the resin substrate. As shown in FIG. 2, the ferrite layer may be provided only on a part of the surface of the resin substrate. The ferrite layer may be provided on both sides as well as on one side of the resin substrate. As shown in FIG. 3, the ferrite layer with partially varied thickness may be provided on the surface of the resin substrate. Additionally, as shown in FIG. 4, the ferrite layer may be wound around the outer circumference of a rod-shaped resin substrate.

[0049] Magnetic composites can be applied in various ways. Such applications include devices or components having coil and / or inductor functions equipped with magnetic composites, electronic devices, light bodies for housing electronic components, electromagnetic wave absorbers, electromagnetic wave shields, or devices or components having antenna functions.

[0050] In this regard, conventional inductor elements were generally surface-mounted on circuit boards as electronic components. In contrast, with the magnetic composite of the present embodiment, inductor elements can be placed inside electronic boards or flexible printed circuit boards (FPC boards). This contributes to the miniaturization of electronic devices. Furthermore, since flexibility can be imparted to the magnetic composite, electronic circuits can be formed on substrates having complex shapes that could not be mounted in the prior art.

[0051] In addition, in the production of electromagnetic shielding materials, conventionally, it was common practice to attach a shielding material punched in a specific shape to a specific location on a finished circuit board. In contrast, by using the composite magnetic material of the present embodiment, it becomes possible to integrally produce a circuit board while incorporating an electromagnetic shielding function in a specific location.

[0052] Figure 5 shows an example of applying a magnetic composite to an inductor. The magnetic composite comprises a resin substrate, a ferrite layer (ferrite film) provided on one surface of the resin substrate, and a coil provided on the surface of the ferrite layer. Additionally, a back electrode is provided on the back side of the resin substrate. The coil is composed of a conductive material such as a metal. Furthermore, the coil has a spiral-shaped planar circuit pattern, and the coil is formed such that the axial direction of the coil is perpendicular to the surface of the ferrite layer. Accordingly, the coil exhibits an inductor function. The circuit pattern of the coil can be formed by methods such as electroless plating, screen printing using a paste containing metal colloidal particles, inkjet, sputtering, or deposition. By forming a circuit pattern on the ferrite layer, a thin device having an inductor function can be obtained.

[0053] Another example of applying a magnetic composite to an inductor is shown in FIG. 6. In this example, a coil is formed to rotate in the thickness direction of the magnetic composite. That is, the magnetic composite is equipped with a surface electrode, a back electrode, and a through electrode connecting the surface electrode and the back electrode, and a coil circuit pattern in the shape of a winding is formed by these electrodes. In this example, the coil is formed such that the axial direction of the coil is parallel to the surface of the ferrite layer.

[0054] Figure 7 shows another example of applying a magnetic composite to an inductor. In this example, a ferrite layer (ferrite film) and a coil are provided on both the outer and inner sides of a resin substrate. Additionally, the coil on the surface side and the coil on the back side are electrically connected through through electrodes provided in the resin substrate and the ferrite layer. By providing inductor functions to both sides of the resin substrate, it is possible to manufacture a miniaturized inductor.

[0055] Figure 8 shows an example of applying a magnetic composite to an antenna element (UHF-ID tag). The antenna element (magnetic composite) comprises a resin substrate, a ferrite layer (ferrite film) provided on one surface of the resin substrate, a metal conductor provided on one surface of the ferrite layer, and a chip for an ID tag mounted on the metal conductor. The metal conductor provided on the surface of the ferrite layer is patterned to form an antenna pattern. Since the ferrite layer has a higher permeability than the surrounding space, electromagnetic waves tend to accumulate on the ferrite layer. By providing an antenna pattern on the ferrite layer, antenna sensitivity can be improved.

[0056] <<2. Method for Manufacturing Magnetic Composite>>

[0057] The manufacturing method of the magnetic composite of the present embodiment is not limited as long as it satisfies the requirements described above. However, a preferred manufacturing method comprises the following steps: a step of preparing a resin substrate and spinel-type ferrite powder having an average particle size (D50) of 2.5 μm or more and 10.0 μm or less (preparation step); and a step of forming a film on the surface of the resin substrate by an aerosol deposition method using the ferrite powder (film formation step).

[0058] In this way, a relatively thick ferrite layer can be produced at a high deposition rate by forming a film using the aerosol deposition method (AD method) with ferrite powder having a specific particle size as a raw material. This ferrite layer is dense, has excellent magnetic and electrical properties, and exhibits excellent adhesion to the substrate. Therefore, it is a desirable method for manufacturing magnetic composites. Each process is described in detail below.

[0059] <Preparation Process>

[0060] In the preparation process, a resin substrate and spinel-type ferrite powder are prepared. The details of the resin substrate are as described above. Meanwhile, as spinel-type ferrite powder, a powder with an average particle size (D50) of 2.5 μm or more and 10.0 μm or less is prepared. The average particle size is preferably 2.5 μm or more and 7.0 μm or less. By adjusting the average particle size to within the above range, a dense ferrite layer with high adhesion can be obtained in the subsequent film formation process.

[0061] The method for producing ferrite powder is not limited. However, preferably, a mixture of ferrite raw materials is subjected to a main calcination in an atmosphere with an oxygen concentration lower than that of the atmosphere to produce a calcined product, and the obtained calcined product is crushed to produce irregular particles of a specific particle size. Additionally, the ferrite raw material mixture may be subjected to a preliminary calcination, crushing, and / or granulation treatment prior to calcination. Known ferrite raw materials, such as oxides, carbonates, and hydroxides, may be used as the ferrite raw materials.

[0062] It is preferable that the shape of the ferrite powder be irregular. Specifically, the average value of the shape factor (SF-2) of the ferrite powder is preferably 1.02 or higher and 1.50 or lower, more preferably 1.02 or higher and 1.35 or lower, and even more preferably 1.02 or higher and 1.25 or lower. Here, SF-2 is an indicator representing the degree of irregularity of the particles; a value closer to 1 indicates a perfectly spherical shape, while a value larger indicates an irregular shape. If SF-2 is excessively small, the particles become too round. Consequently, it is difficult for the particles to adhere to the substrate, making it impossible to increase the film deposition speed. On the other hand, if SF-2 is excessively large, the surface irregularities of the particles become too large. Consequently, although the film deposition speed increases, voids are likely to remain in the resulting ferrite layer due to the surface irregularities of the particles. If SF-2 is within the above range, it becomes possible to obtain a dense ferrite layer at a high film deposition speed. Meanwhile, SF-2 can be obtained according to the following formula (1).

[0063]

[0064] In addition, the average value of the aspect ratio of the ferrite powder is preferably 1.00 or higher and 2.00 or lower, more preferably 1.02 or higher and 1.75 or lower, and even more preferably 1.02 or higher and 1.50 or lower. If the aspect ratio is within the above range, the gas flow supplying the raw material during film formation becomes stable. On the other hand, if it exceeds the above range, the raw material is prone to clogging in the piping from the raw material supply container to the nozzle. Therefore, there is a risk that the film formation speed will become unstable as the film formation time progresses. Meanwhile, the aspect ratio can be calculated according to the following formula (2).

[0065]

[0066] In addition, the CV value of the ferrite powder particle size is preferably 0.5 or higher and 2.5 or lower. Here, the CV value indicates the degree of non-uniformity of the particle size in the powder; it becomes smaller as the particle size is more uniform and larger as it is more non-uniform. It is difficult to obtain powder with a value lower than 0.5 using general grinding methods (bead mill, jet mill, etc.) for obtaining irregular particles. On the other hand, powder with a value greater than 2.5 is prone to clogging in the piping from the raw material supply container to the nozzle. Therefore, there is a concern that the film formation speed may become unstable as the film formation time progresses. Meanwhile, the CV value can be calculated by the following equation (3) using the 10% cumulative diameter (D10), 50% cumulative diameter (D50; average particle size), and 90% cumulative diameter (D90) in the volumetric particle size distribution.

[0067]

[0068] When plasticizing is performed during the production of ferrite powder, plasticizing can be carried out, for example, under an atmospheric condition at 500 to 1,100°C for 1 to 24 hours. Additionally, when sintering is carried out, the sintering can be carried out, for example, under an atmosphere such as an atmospheric or reducing atmosphere at 800 to 1,350°C for 4 to 24 hours. Furthermore, it is preferable that the oxygen concentration during the sintering be low. This is because it allows for the intentional creation of lattice defects within the spinel crystals of the ferrite powder. If lattice defects are present within the crystals, plastic deformation is likely to occur starting from these lattice defects when raw material particles collide with the substrate during the subsequent film deposition process. Consequently, a dense ferrite layer with high adhesion can be easily obtained. The oxygen concentration is preferably 0.001 to 10 volume%, more preferably 0.001 to 5 volume%, and even more preferably 0.001 to 2 volume%. Furthermore, when the ferrite contains copper (Cu), it is preferable to perform calcination under a reducing atmosphere. When calcined under a reducing atmosphere, copper(II) oxide (CuO) releases some oxygen atoms and changes into copper(I) oxide (Cu2O). At this time, lattice defects are likely to form. In addition, making the ferrite powder an iron (Fe)-rich composition is also effective for obtaining a dense ferrite layer.

[0069] The sintered product is preferably ground using a grinder such as a dry bead mill. By dry grinding, mechanochemical treatment is performed on the sintered product, which reduces the crystallite diameter and increases surface activity. The ground powder with high surface activity contributes to the densification of the ferrite layer obtained in the subsequent film formation process, along with the effect of an appropriate particle size. The crystallite diameter (CSp) of the ferrite powder is preferably 10 Å or more and 50 Å or less. By using ferrite powder with a fine crystallite diameter, a dense ferrite layer can be obtained.

[0070] <Tabernacle Construction>

[0071] In the film deposition process, ferrite powder is deposited on the surface of a resin substrate using the aerosol deposition method (AD method). The aerosol deposition method (AD method) is a technique that forms a film by high-speed spraying of aerosolized raw material fine particles onto a substrate and utilizing the room-temperature impact solidification phenomenon. Because it utilizes the room-temperature impact solidification phenomenon, it is possible to form a dense film with high adhesion. Furthermore, since fine particles are used as feedstock, thick films can be obtained at a rapid deposition rate compared to thin film formation methods such as sputtering or deposition, which separate raw materials down to the atomic level. Additionally, since room-temperature deposition is possible, there is no need to complicate the configuration of the equipment, resulting in cost savings.

[0072] An example of the configuration of an aerosol deposition film forming device is shown in FIG. 9. The aerosol deposition film forming device (20) comprises an aerosolization chamber (2), a film forming chamber (4), a return gas source (6), and a vacuum exhaust system (8). The aerosolization chamber (2) comprises a vibrator (10) and a raw material container (12) placed thereon. Inside the film forming chamber (4), a nozzle (14) and a stage (16) are provided. The stage (16) is configured to move perpendicularly to the spraying direction of the nozzle (14).

[0073] During film formation, a return gas is introduced from a return gas source (6) into a raw material container (12), and a vibrator (10) is operated. Raw material fine particles (ferrite powder) are loaded into the raw material container (12). Due to vibration, the raw material fine particles are mixed with the return gas and aerosolized. Additionally, the film formation chamber (4) is vacuum-evacuated by a vacuum exhaust system (8) to reduce the pressure inside the chamber. The aerosolized raw material fine particles are returned into the film formation chamber (4) by the pressure difference and sprayed from a nozzle (14). The sprayed raw material fine particles collide with the surface of a substrate (substrate) mounted on a stage (16) and are deposited there. At this time, the kinetic energy of the raw material fine particles, which are accelerated by the gas return, is locally released upon collision with the substrate, thereby realizing bonding between the substrate and the particles, and between the particles themselves. Therefore, it is possible to form a dense film. By moving the stage (16) during film formation, it is possible to form a film that has diffusivity in the planar direction.

[0074] The reason a dense ferrite layer is obtained by the manufacturing method of the present embodiment is presumed as follows. That is, ceramics are generally referred to as materials that have a high elastic limit and are difficult to plastically deform. However, it is presumed that when raw material fine particles collide with the substrate at high speed during film formation in the aero deposition method, a large impact force is generated as the elastic limit is exceeded, causing the fine particles to plastically deform. Specifically, defects such as misalignment of crystal planes or dislocation movement occur within the fine particles, and to compensate for these defects, plastic deformation occurs, and the crystal structure becomes finer. In addition, new planes are formed, and mass transfer occurs. It is presumed that as a result of the combined action of these factors, the bonding strength between the substrate and particles and between particles increases, resulting in a dense film. Furthermore, it is presumed that during plastic deformation, a portion of the ferrite decomposes and reoxidizes, generating α-Fe2O3, which contributes to increased resistance. In addition, it is speculated that during the initial stage of film formation, microparticles colliding with the resin substrate penetrate into the interior of the substrate, and by exhibiting an anchoring effect, the adhesion between the ferrite layer and the substrate is enhanced.

[0075] In obtaining a dense ferrite layer, the average particle size of the raw ferrite powder is important. In this embodiment, the average particle size (D50) of the ferrite powder is limited to 2.5 μm or more and 10.0 μm or less. If the average particle size is less than 2.5 μm, it becomes difficult to obtain a dense film. This is because powders with a small average particle size have a small mass of the particles constituting them. Aerosolized raw fine particles collide with the substrate at high speed along with a carrier gas. The carrier gas that collides with the substrate changes direction and flows as exhaust gas. Particles with small particle size and small mass are pushed by the exhaust flow of the carrier gas, and the collision velocity with the substrate surface and the resulting impact force are reduced. If the impact force is small, the plastic deformation received by the fine particles is insufficient, and the crystallite diameter does not decrease. The formed film does not become dense, and becomes a compacted body in which the powder is merely compressed. Such a compacted body contains a large number of holes internally, and its magnetic and electrical properties are degraded. Furthermore, the adhesion to the substrate is not increased. On the other hand, when the average particle size exceeds 10.0 μm and is excessively large, the impact force received by a single particle is large, but the number of contact points between particles decreases. Consequently, plastic deformation and packing become insufficient, making it difficult to obtain a dense film.

[0076] The film deposition conditions according to the aerosol deposition method are not particularly limited as long as a dense ferrite layer with high adhesion can be obtained. Air or an inert gas (nitrogen, argon, helium, etc.) may be used as the carrier gas. However, an atmosphere (air) that is easy to handle is preferred. The flow rate of the carrier gas may be, for example, 1.0 to 20.0 L / min. In addition, the internal pressure of the film deposition chamber may be, for example, 10 to 50 Pa before film deposition and 50 to 400 Pa during film deposition. The scanning speed (movement speed) of the resin substrate (stage) may be, for example, 1.0 to 10.0 mm / sec. Coating (film deposition) may be performed only once or multiple times. However, from the perspective of sufficiently securing the film thickness of the obtained ferrite layer, it is preferable to perform it multiple times. The number of coatings is, for example, 5 times or more and 100 times or less.

[0077] The ratio (LCf / LCp) of the lattice constant of the spinel phase (LCf) contained in the ferrite layer to the lattice constant of the spinel phase (LCp) contained in the raw ferrite powder is preferably 0.95 or higher and 1.05 or lower (0.95 ≤ LCf / LCp ≤ 1.05). The spinel phase in the raw ferrite powder has an oxygen-deficient composition and is prone to containing lattice defects. Consequently, the lattice constant tends to increase compared to a state where lattice defects are absent. Meanwhile, when the raw ferrite powder is subjected to aerosol deposition film formation treatment, plastic deformation occurs starting from the lattice defects. Furthermore, active faces are formed due to plastic deformation, and these active faces are oxidized. Since the reconstruction of the crystal structure and the re-oxidation of the active faces occur, the lattice constant is prone to change. By controlling the lattice constant ratio (LCf / LCp) within the above range, the amount of α-Fe2O3 involved in the reconstruction of the crystal structure and reoxidation of the active surface can be adjusted to a desired range, and as a result, a ferrite layer with excellent electrical properties (electrical insulation) can be formed while maintaining excellent magnetic properties. More preferably, the lattice constant ratio (LCf / LCp) is 0.99 or higher and 1.04 or lower.

[0078] The degree of variation in lattice constants depends on the manufacturing conditions or composition of the raw ferrite powder, as well as the material and type of the substrate. Specifically, the ferrite composition is stoichiometric or iron-rich (Fe) composition (M X Fe 3-XIn the case of O4 (0 < x ≤ 1, M is a metal atom), although it depends on the sintering conditions, the amount of oxygen contained in the raw ferrite powder tends to be substantially lower than the stoichiometric ratio. Consequently, the lattice constant of the raw ferrite powder tends to increase. On the other hand, in the ferrite layer deposited by the AD method, the crystal structure is reorganized due to oxidation accompanying the sintering deformation of the raw particles; therefore, the lattice constant tends to be smaller than that of the raw ferrite powder. This tendency is particularly pronounced when using ferrite powder containing lithium (Li) or manganese (Mn), or ferrite powder sintered under oxygen concentrations lower than atmospheric levels. Consequently, in these cases, the LCf / LCp tends to be less than 1.00.

[0079] The amount of Fe is the stoichiometric ratio of ferrite (M X Fe 3-X When O4 (0 < x ≤ 1, M is a metal atom) is less than 0, the amount of oxygen contained in the ferrite tends to be equal to the stoichiometric ratio. In addition, in ferrite layers deposited by the aerosol deposition method, the lattice constant tends to increase because lattice defects caused by plastic deformation increase. This tendency is particularly pronounced when using ferrite powder containing copper (Cu) or ferrite powder calcined under an atmospheric atmosphere. Therefore, in this case, the LCf / LCp tends to exceed 1.00.

[0080] The lattice constant ratio (LCf / LCp) can be adjusted by controlling the aerosol deposition film formation conditions. Specifically, increasing the collision velocity of the raw material microparticles can accelerate the progression of deformation and re-oxidation. The collision velocity of the raw material microparticles can be varied by adjusting the chamber internal pressure. Furthermore, excessive re-oxidation can be prevented by altering the film formation speed. Since re-oxidation proceeds from the surface of the raw material microparticles, increasing the film formation speed of the ferrite layer shortens the exposure time of the raw material microparticles to the atmosphere, thereby suppressing the progression of re-oxidation.

[0081] The ratio (CSf / CSp) of the spinel-shaped crystallite diameter (CSf) contained in the ferrite layer to the spinel-shaped crystallite diameter (CSp) contained in the raw ferrite powder is preferably 0.01 or more and 0.50 or less (0.01 ≤ CSf / CSp ≤ 0.50). The crystallite diameter of the ferrite changes as it undergoes aerosol deposition film formation. This is because deformation occurs upon collision with the substrate, and the active surface is reoxidized. Even if film formation is performed under conditions where the crystallite diameter ratio (CSf / CSp) becomes excessively small, a dense ferrite layer with high adhesion cannot be obtained. This is because the internal stress of the ferrite layer becomes too large. Furthermore, even if film formation is possible, the ferrite layer easily peels off due to internal stress. Consequently, stability over time is lacking. The crystallite diameter ratio (CSf / CSp) is more preferably 0.05 or more and 0.30 or less, and even more preferably 0.10 or more and 0.20 or less.

[0082] In this way, a magnetic composite of the present embodiment can be obtained. In the obtained magnetic composite, the ferrite layer is dense, so the magnetic properties and electrical properties (electrical insulation) are excellent. In addition, the adhesion to the resin substrate is high. In fact, the inventors have succeeded in producing a magnetic composite having a ferrite layer with a relative density of 0.95 or higher and an adhesion strength of 8H on a pencil hardness scale. Furthermore, the ferrite layer has relatively low magnetic loss in the high-frequency region. Moreover, although not limited to, the magnetic composite having a thin-layered resin substrate has flexibility, making it possible to manufacture devices with complex shapes. A magnetic composite having such a ferrite layer can be used not only as an electromagnetic wave absorber but also for electronic components such as transformers, inductance elements, and impedance elements, and is particularly desirable for UHF tags, 5G filters, and high-frequency inductors.

[0083] The technology for producing the magnetic composite of the present embodiment is not known prior to the present invention, to the best of the inventors' knowledge. For example, the ferrite thin film proposed in Patent Document 1 is difficult to form thickly during manufacturing. In fact, Patent Document 1 discloses forming an Mn-Zn ferrite film on a polyethylene terephthalate film by a counter-target type magnetron sputtering method, but the film thickness of the ferrite layer is only 3 nm (paragraph

[0030] ). Furthermore, Patent Document 2 uses ferrite microparticles with a sub-micron particle size as a raw material (paragraph

[0036] ), and it is difficult to form a ferrite film with a dense and high adhesion using such fine raw materials. Patent Document 3 discloses the production of a radio wave absorber using the AD method (paragraphs

[0020] to

[0021] ), but the particle size of the raw ferrite particles is not disclosed, and the details of properties other than radio wave absorption properties of the obtained ferrite layer are unclear (paragraphs

[0020] to

[0022] ).

[0084] Examples

[0085] The present invention will be explained in more detail using the following examples. However, the present invention is not limited to the following examples.

[0086] (1) Fabrication of magnetic composites

[0087] [Example 1]

[0088] In Example 1, ferrite powder with MnZn-based ferrite as the main component was prepared, and the obtained ferrite powder was deposited onto a polycarbonate (PC) plate (resin substrate) to produce a magnetic composite. The preparation and deposition of the ferrite powder were carried out in the following order.

[0089] <Production of Ferrite Powder>

[0090] Iron oxide (Fe2O3), trimanganese tetroxide (Mn3O4), and zinc oxide (ZnO) were used as raw materials, and the materials were weighed and mixed to achieve a molar ratio of F2O3:Mn3O4:ZnO = 53:12.3:10. Mixing was performed using a Henschel mixer. The obtained mixture was molded using a roller compactor to obtain an aggregate (pre-aggregate).

[0091] Next, the assembled raw material mixture (pre-assembled material) was plasticized to produce a plasticized product. Plasticization was carried out using a rotary kiln under atmospheric conditions of 880°C × 2 hours.

[0092] Subsequently, the obtained plastic material was crushed and granulated to produce an aggregate (main aggregate). First, the plastic material was coarsely ground using a dry bead mill (φ3 / 16 inch steel beads), water was added, and the mixture was finely ground using a wet bead mill (φ0.65 mm zirconium oxide beads) to form a slurry. The resulting slurry had a solid content concentration of 50 mass% and a particle size of the crushed powder (slurry particle size) of 2.15 μm. To the obtained slurry, an ammonium polycarboxylate salt was added as a dispersant at a ratio of 50 cc per 25 kg of solid content in the slurry, and a 10 mass% aqueous solution of polyvinyl alcohol (PVA) was added as a binder at a volume of 500 cc. Afterward, the slurry containing the dispersant and binder was granulated using a spray dryer to obtain the main aggregate.

[0093] Then, the obtained main assembly was fired (main firing) using an electric furnace under a non-oxidizing atmosphere at 1,250°C for 4 hours to produce a fired product. Subsequently, the obtained fired product was crushed using a dry bead mill (φ3 / 16 inch steel ball beads) to obtain a crushed fired product.

[0094] <Tabernacle>

[0095] Using the obtained pulverized sintered material, a ferrite layer was deposited on the surface of a resin substrate. A polycarbonate (PC) plate with a thickness of 500 μm was used as the resin substrate. This PC plate was colorless and transparent. In addition, the film deposition was performed under the following conditions by the aerosol deposition method (AD method).

[0096] Carrier gas (return gas): Air

[0097] Gas flow rate: 5.0 L / min

[0098] Internal pressure of the tabernacle chamber (before the tabernacle): 30 Pa

[0099] Internal pressure of the tabernacle chamber (at the tabernacle): 120 Pa

[0100] Substrate scan speed: 5mm / sec

[0101] Number of coatings: 10 times

[0102] Distance from material to nozzle: 20mm

[0103] Nozzle shape: 10mm × 0.4mm

[0104] [Example 2]

[0105] In Example 2, the number of coatings during film formation was changed from 10 to 20. Otherwise, a magnetic composite was fabricated in the same manner as in Example 1.

[0106] [Example 3]

[0107] In Example 3, a polyimide (PI) film with a thickness of 50 μm was used as the resin substrate. This PI film was brown and transparent. A magnetic composite was prepared in the same manner as in Example 1.

[0108] [Example 4]

[0109] In Example 4, a polyvinyl chloride (PVC) plate with a thickness of 500 μm was used as the resin substrate. This PVC plate was colorless and transparent. Except for that, a magnetic composite was fabricated in the same manner as in Example 1.

[0110] [Example 5]

[0111] In Example 5, a polyoxymethylene (POM) plate with a thickness of 500 μm was used as the resin substrate. This POM plate was white and opaque. A magnetic composite was prepared in the same manner as in Example 1.

[0112] [Example 6]

[0113] In Example 6, an acrylonitrile-butadiene-styrene (ABS) plate with a thickness of 500 μm was used as the resin substrate. This ABS plate was milky white and opaque. A magnetic composite was fabricated in the same manner as in Example 1.

[0114] [Example 7]

[0115] In Example 7, a polyetheretherketone (PEEK) plate with a thickness of 5,000 μm was used as the resin substrate. This PEEK plate was gray and opaque. A magnetic composite was fabricated in the same manner as in Example 1.

[0116] [Example 8]

[0117] In Example 8, a polyamide (PA) plate with a thickness of 5,000 μm was used as the resin substrate. This PA plate was blue and opaque. A magnetic composite was fabricated in the same manner as in Example 1.

[0118] [Example 9 (Comparative Example)]

[0119] In Example 9, a polypropylene (PP) plate with a thickness of 500 μm was used as the resin substrate. This PP plate was white and translucent. A magnetic composite was fabricated in the same manner as in Example 1.

[0120] [Example 10 (Comparative Example)]

[0121] In Example 10, a polymethyl methacrylate (PMMA) plate with a thickness of 500 μm was used as the resin substrate. This PMMA plate was colorless and transparent. A magnetic composite was prepared in the same manner as in Example 1, except for the above.

[0122] [Example 11]

[0123] In Example 11, raw material particles (ferrite powder) with NiCuZn-based ferrite as the main component were prepared, and then the obtained ferrite powder was deposited onto a polycarbonate (PC) plate to produce a magnetic composite. The preparation of the ferrite powder and the deposition were carried out in the following order.

[0124] <Production of Ferrite Powder>

[0125] Iron oxide (Fe2O3), zinc oxide (ZnO), nickel oxide (NiO), and copper oxide (CuO) were used as raw materials, and the materials were weighed and mixed to achieve a molar ratio of Fe2O3:ZnO:NiO:CuO = 48.5:33:12.5:6. A Henschel mixer was used for mixing. The resulting mixture was molded using a roller compactor to obtain an assembly (pre-assembly).

[0126] Next, the assembled raw material mixture (pre-assembled material) was plasticized to produce a plasticized product. Plasticization was carried out using a rotary kiln under atmospheric conditions of 910°C × 2 hours.

[0127] Subsequently, the obtained plastic material was crushed and granulated to produce an aggregate (main aggregate). First, the plastic material was coarsely ground using a dry bead mill (φ3 / 16 inch steel ball beads), water was added, and the mixture was finely ground using a wet bead mill (φ0.65 mm zirconium oxide beads) to form a slurry. The resulting slurry had a solid content concentration of 50 mass% and a particle size of the crushed powder (slurry particle size) of 2.77 μm. To the obtained slurry, an ammonium polycarboxylate salt was added as a dispersant at a ratio of 50 cc per 25 kg of solid content in the slurry, and a 10 mass% aqueous solution of polyvinyl alcohol (PVA) was added as a binder at a ratio of 250 cc. Afterward, the slurry containing the dispersant and binder was granulated using a spray dryer to obtain the main aggregate.

[0128] Then, the original assembly was fired (original firing) using an electric furnace under an oxidizing atmosphere at 1,100°C for 4 hours to produce a fired product. Subsequently, the obtained fired product was ground using a dry bead mill (φ3 / 16 inch steel ball beads) to obtain a ground fired product.

[0129] <Tabernacle>

[0130] Using the obtained crushed and calcined material, a ferrite layer was formed on the surface of a resin substrate. A polycarbonate (PC) plate with a thickness of 500 μm was used as the resin substrate. The formation was carried out using the same method as in Example 1.

[0131] [Example 12 (Comparative Example)]

[0132] In Example 12, the processing conditions for dry bead mill treatment of the sintered product were changed to obtain a finely ground sintered product. A magnetic composite was produced in the same manner as in Example 11, except for the above.

[0133] [Example 13 (Comparative Example)]

[0134] In Example 13, the processing conditions for dry bead mill treatment of the sintered product were changed to obtain a finely ground sintered product. A magnetic composite was produced in the same manner as in Example 1, except for the above.

[0135] [Example 14 (Comparative Example)]

[0136] In Example 14, the number of coatings during film formation was changed from 10 to 1. Otherwise, a magnetic composite was fabricated in the same manner as in Example 1.

[0137] [Example 15 (Comparative Example)]

[0138] In Example 15, the gas flow rate during film deposition was changed from 5.0 L / min to 1.0 L / min. In addition, the internal pressure of the film deposition chamber (during film deposition) was changed from 120 Pa to 80 Pa. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0139] [Example 16 (Comparative Example)]

[0140] In Example 16, the gas flow rate during film deposition was changed from 5.0 L / min to 2.5 L / min. In addition, the internal pressure of the film deposition chamber (during film deposition) was changed from 120 Pa to 100 Pa. Otherwise, the magnetic composite was fabricated in the same manner as in Example 1.

[0141] [Examples 17–25]

[0142] Magnetic composites were fabricated by changing the manufacturing conditions of the magnetic composites as shown in Tables 1 and 2.

[0143] The manufacturing conditions of ferrite powder and magnetic composites for Examples 1 to 25 are summarized in Tables 1 and 2.

[0144]

[0145]

[0146] (2) Evaluation

[0147] For Examples 1 to 25, various characteristic evaluations were performed on the ferrite powder, resin substrate, and magnetic composite as follows.

[0148] <Particle Shape (Raw Powder)>

[0149] The average SF-2 value and the average aspect ratio of the ferrite powder were calculated as follows. Ferrite powder was analyzed using a particle image analyzer (Spectris, Morphology G3), and for 30,000 particles, the projected periphery, projected area, major axis Ferret diameter, and minor axis Ferret diameter were calculated. The analysis was performed using an objective lens with a magnification of 20x. Then, using the obtained data, the SF-2 and aspect ratio were calculated for each particle according to the following equations (1) and (2), and the average values ​​were calculated.

[0150]

[0151]

[0152] <Particle Size Distribution (Raw Material Particles)>

[0153] The particle size distribution of the ferrite powder was measured as follows. First, 0.1 g of the sample and 20 ml of water were placed in a 30 ml beaker, and two drops of sodium hexametaphosphate were added as a dispersant. Subsequently, the mixture was dispersed using an ultrasonic homogenizer (SMT Co., Ltd., UH-150). At this time, the output level of the ultrasonic homogenizer was set to 4, and dispersion was performed for 20 seconds. Afterward, the bubbles formed on the surface of the beaker were removed, and the mixture was introduced into a laser diffraction particle size distribution measuring device (Shimadzu Seisakusho Co., Ltd., SALD-7500 nano) to perform the measurement. Through this measurement, the 10% cumulative diameter (D10), 50% cumulative diameter (D50; average particle size), and 90% cumulative diameter (D90) in the volumetric particle size distribution were determined. The measurement conditions were set to a pump speed of 7, an internal ultrasonic irradiation time of 30, and a refractive index of 1.70-0.50 i. Then, using D10, D50 and D90, the CV value was calculated according to the following equation (3).

[0154]

[0155] <XRD(Raw Powder, Ferrite Layer)>

[0156] X-ray diffraction (XRD) analysis was performed on the ferrite powder and the ferrite layer of the magnetic composite. The analysis conditions were as shown below.

[0157] - X-ray diffraction device: Panalytical X’pert MPD (including high-speed detector)

[0158] - Sailor: Co-Kα

[0159] - Tube voltage: 45kV

[0160] - Tube current: 40mA

[0161] - Scan speed: 0.002° / sec (continuous scan)

[0162] - Scan range (2θ): 15~90°

[0163] In the obtained X-ray diffraction profile, the integrated intensity (I) of the (222) plane diffraction peak on the spinel 222 ) and (311) plane diffraction peak integrated intensity (I 311 Calculate ) and the XRD peak intensity ratio (I 222 / I 311 ) was calculated. In addition, the content ratios of the spinel phase and α-Fe2O3 were determined based on the X-ray diffraction profile.

[0164] In addition, the lattice constants (LCp, LCf) of the spinel phase were estimated by analyzing the X-ray diffraction profile using Rietveld analysis, and the crystallite diameters (CSp, CSf) of the spinel phase were calculated according to Scherrer's formula. Then, the rate of change in the lattice constants (LCf / LCp) and crystallite diameters (CSf / CSp) of the spinel phase before and after film deposition were calculated.

[0165] <Magnetic Properties (Raw Particles, Magnetic Composites)>

[0166] The magnetic properties (saturation magnetization, remanent magnetization, and coercivity) of ferrite powder and magnetic composites were measured as follows. First, a sample was filled into a cell with an inner diameter of 6 mm and a height of 2 mm and set up in a vibrating sample type magnetic measuring device (Toei High School Co., Ltd., VSM-C7-10A). An applied magnetic field was applied and swept to 5 kOe, and then the applied magnetic field was reduced to draw a hysteresis curve. From the data of the obtained curve, the saturation magnetization (σs), remanent magnetization (σr), and coercivity (Hc) of the sample were determined.

[0167] Meanwhile, when the thickness of the magnetic composite, including the ferrite layer, is 2 mm or less, the magnetic composite was processed into a disc shape with an outer diameter of 6 mm, and the processed magnetic composite was filled into a cell for measurement. When the thickness of the magnetic composite, including the ferrite layer, is more than 2 mm, the surface of the magnetic composite where the ferrite layer is not formed (resin surface) was ground to a thickness of 500 μm, punched into a disc shape with an outer diameter of 6 mm, and the punched magnetic composite was filled into a cell for measurement.

[0168] <True Specific Gravity (Raw Material Particles)>

[0169] The true specific gravity of the raw material particles was measured by the gas displacement method in accordance with JIS Z8837:2018.

[0170] <Thickness and Elemental Distribution (Ferrite Layer)>

[0171] The cross-section of the ferrite layer was observed using a field emission scanning electron microscope (FE-SEM), and its thickness was determined. Then, elemental mapping analysis of the cross-section was performed using an energy dispersive X-ray analyzer (EDX) attached to the microscope, and a mapping image was obtained.

[0172] <Density (Ferrite Layer)>

[0173] The density of the ferrite layer was measured as follows. First, the mass of the resin substrate was measured before the ferrite layer was formed. Next, the mass of the resin substrate was measured after the ferrite layer was formed, and the difference from the mass of the resin substrate was calculated to determine the mass of the ferrite layer. In addition, the formation area and thickness of the ferrite layer were measured. The thickness was determined by observing the cross-section of the ferrite layer using a scanning electron microscope (SEM). Then, the density of the ferrite layer was calculated according to the following equation (4).

[0174]

[0175] <Surface Roughness (Resin Substrate, Ferrite Layer)>

[0176] The arithmetic mean height (Sa) and maximum height (Sz) of the surfaces of the resin substrate and the ferrite layer, respectively, were evaluated using a laser microscope (LaserTech Co., Ltd., OPTELICS HYBRID). Ten measurements were taken for each sample, and the average value was calculated. The measurements were performed in accordance with JIS B 0601-2001. In addition, the thickness (d) relative to the arithmetic mean height (Sa) of the ferrite layer F From ), roughness ratio (Sa / d F ) was produced.

[0177] <Surface Resistance (Resin Substrate, Ferrite Layer)>

[0178] The surface resistance of the ferrite layer was measured using a resistivity meter (Mitsubishi Chemical Corporation, LorestaHP MCP-T410). Ten measurements were taken for each sample, and the average value was calculated.

[0179] <Permeability (Magnetic Complex)>

[0180] The permeability of the magnetic composite was measured using a microstrip line complex permeability measurement method with a vector network analyzer (Keysight, PNA N5222B, 10 MHz to 26.5 GHz) and a permeability measurement jig (Keycom Co., Ltd.). Specifically, the magnetic composite was cut and set on the permeability measurement jig as a measurement sample. Subsequently, the measurement frequency in the range of 100 MHz to 10 GHz was scanned on a logarithmic scale. The real part (μ') and imaginary part (μ") of the complex permeability at a frequency of 1 GHz were obtained, and the loss coefficient (tanδ) was calculated according to the following equation (5).

[0181]

[0182] Meanwhile, when the thickness of the magnetic composite, including the ferrite layer, is 1 mm or less, the magnetic composite is processed into a strip shape with a width of 5 mm and a length of 10 mm, and the processed magnetic composite is set on a measuring jig and measured. When the thickness of the magnetic composite, including the ferrite layer, exceeds 1 mm, the resin surface of the magnetic composite where the ferrite layer is not formed is ground to a thickness of 500 μm, processed into a strip shape with a width of 5 mm and a length of 10 mm, and the processed magnetic composite is set on a measuring jig and measured.

[0183] <Flexibility (Magnetic Composite)>

[0184] The flexibility of a magnetic composite (substrate thickness 50 μm) was evaluated by winding it onto an inch tube. Specifically, three types of inch tubes were prepared: one with an outer diameter of 1 / 16 inch, one with an outer diameter of 1 / 8 inch, and one with an outer diameter of 1 / 4 inch. The magnetic composite was wound onto each inch tube with the ferrite layer facing outward. Then, the condition of the ferrite layer was visually observed and graded from ○ to × according to the following criteria.

[0185] ○: No change was observed in the ferrite layer before and after winding.

[0186] △: Cracks occurred in the ferrite layer after winding.

[0187] ×: The ferrite layer peeled off after winding.

[0188] <Adhesion (Magnetic Composite)>

[0189] The adhesion between the ferrite layer and the resin substrate was evaluated by a pencil hardness test (pencil scratch test). Measurements were performed in accordance with the former JIS K5400. In each test, scratching was repeated 5 times with a pencil of the same density symbol. At that time, the tip of the pencil lead was sharpened for each scratch. Meanwhile, the pencil hardness increases in the order of 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9H, and 10H, and higher hardness indicates better adhesion.

[0190] <Adhesion (Magnetic Composite)>

[0191] The adhesion between the ferrite layer and the resin substrate of magnetic composites (substrate thicknesses 500 μm and 5000 μm) was evaluated using the cross-cutting method. Measurements were performed in accordance with JIS K5600-5-6:1999. In addition, based on the obtained evaluation results, the samples were graded according to the following criteria.

[0192] A: The edges of the cut are completely smooth, and there is no peeling in any of the grid eyes.

[0193] B: There is small peeling of the film at the intersection of the cuts. The number of affected parts in the cross-cut section does not clearly exceed 5%.

[0194] C: The film peeled off along the cutting edges and / or at the intersections. The number of affected parts in the cross-cut section clearly exceeds 5% but does not exceed 15%.

[0195] D: The film has peeled significantly, partially or completely, along the cutting edge, and / or several parts of the eye have peeled partially or completely. The number of affected areas in the cross-cut section clearly exceeds 15% but does not exceed 35%.

[0196] E: The coating has peeled off significantly, partially or completely, along the cutting edge, and / or the eyes at multiple points have peeled off partially or completely. The number of affected areas in the cross-cut section does not clearly exceed 65%.

[0197] F: The degree of peeling cannot be classified from A to E.

[0198] (3) Evaluation results

[0199] For Examples 1 to 25, the characteristics of the ferrite powder and the characteristics of the resin substrate are shown in Tables 3 and 4, respectively. In addition, the characteristics of the magnetic composite are shown in Tables 5 and 6.

[0200] As shown in Table 3, the ferrite powders used for film formation in Examples 1–11 and 14–25 all had a high spinel phase content of 99 mass% or more, and the synthesis of spinel-type ferrite proceeded sufficiently. In addition, the XRD peak intensity ratio (I 222 / I 311 The value was approximately 0.04 to 0.05, and it was comparable to general spinel-type ferrite. In addition, the average particle size (D50) was 3.6 to 5.2 μm, and the crystallite diameter was approximately 10 to 18 nm. On the other hand, the ferrite powders of Example 12 and Example 13 had a low spinel phase content of less than 96 mass%. In addition, the crystallite diameter was small, approximately 2 to 5 nm, and the magnetic properties were poor. It is presumed that oxidation of the raw material occurred because the grinding conditions during dry bead mill processing were strengthened to finely pulverize it.

[0201] As shown in Tables 5 and 6, the magnetic composites of Examples 1–8, Example 11, and Examples 17–25 have a ferrite layer thickness (d F ) is 2.0μm or greater, and the XRD peak intensity ratio (I 222 / I 311 ) was zero (0). In addition, the amount of α-Fe2O3 was about 0.5 to 19.7 mass%, and the crystallite diameter was small, less than 2.20 nm. Therefore, these samples had relatively high relative density and adhesion, and high surface resistance. In particular, Examples 1, 4, 7, and 8 had a very high relative density of over 90%, and the results of the adhesion test were also excellent, with a pencil hardness of 5H or higher. In addition, the magnetic composites of Examples 3 and 17 to 25 had good results in the flexibility test.

[0202] Meanwhile, in Example 9, since polypropylene with low specific gravity was used as the substrate, the adhesion to the substrate was weak, and a low-density ferrite layer was formed, so sufficient magnetic properties were not obtained. In addition, in Example 10, the resin substrate was erased by the ferrite powder sprayed at high speed during film formation, making it impossible to form a ferrite layer. This is presumed to be because the compatibility between the resin (PMMA) constituting the substrate and the ferrite powder was poor, and the anchoring effect did not function properly. Furthermore, in Examples 12 to 16, it appeared that a ferrite layer could be formed, but the ferrite layer peeled off immediately when rubbed with a finger. In particular, Examples 12 to 15 resulted in a laminate of powders called a compact, showing a result that did not reach film formation. Consequently, in Examples 10 and 12 to 16, the film formation was non-uniform (stained), making it impossible to measure various properties.

[0203] Cross-sectional elemental mapping images of the ferrite layer of the magnetic composite obtained for Example 1 are shown in FIGS. 10 (a) to (f). Here, FIGS. 10 (a) to (f) are, respectively, an electron beam image (a), a carbon (C) mapping image (b), an oxygen (O) mapping image (c), a manganese (Mn) mapping image (d), an iron (Fe) mapping image (e), and a zinc (Zn) mapping image (f). In addition, FIGS. 10 (a) to (f) show the resin substrate on the lower side and the ferrite layer on the upper side.

[0204] The constituent elements of the resin substrate and the ferrite layer were clearly separated. That is, carbon (C) was present on the substrate side, while manganese (Mn), iron (Fe), zinc (Zn), and oxygen (O) were present only on the ferrite layer side. From this, it was revealed that no elemental diffusion occurred between the resin substrate and the ferrite layer due to reaction.

[0205] Figure 11 shows the permeability (real part μ', imaginary part μ") of the magnetic composite obtained for Example 1. It was found that μ' exhibits a constant value when μ' is nearly zero across the frequency range from low frequency to high frequency ranges above 1 GHz, and that μ' takes a maximum value at frequencies above 1 GHz.

[0206] From these results, it was found that the magnetic composite of the present embodiment is dense, has a relatively thick film, and has a ferrite layer with excellent magnetic properties and better adhesion.

[0207]

[0208]

[0209]

[0210] Industrial applicability

[0211] According to the present invention, a magnetic composite is provided having a ferrite layer that is dense, has a relatively thick film, has excellent magnetic and electrical properties, and has even better adhesion.

[0212] Although the present invention has been described in detail with reference to specific embodiments, it is obvious to those skilled in the art that various changes or modifications can be made without departing from the spirit and scope of the invention.

[0213] This application is based on Japanese Patent Application No. 2021-018761 filed on February 9, 2021, Japanese Patent Application No. 2022-017459 filed on February 7, 2022, and Japanese Patent Application No. 2022-018310 filed on February 8, 2022, the contents of which are incorporated herein by reference. Explanation of the symbols

[0214] 2: Aerosolization Chamber 4: Tabernacle Chamber 6: Return gas source 8: Vacuum exhaust system 10: Vibrator 12: Raw material container 14: Nozzle 16: Stage 20: Aerosol Deposition Tabernacle Device

Claims

Claim 1 A magnetic composite having a resin substrate and a ferrite layer provided on the surface of the resin substrate, wherein the resin substrate has a thickness (d R ) is 10μm or more, and the ferrite layer has a thickness (d F ) is 2.0 μm or greater, consists mainly of spinel-type ferrite, and in X-ray diffraction analysis the integrated intensity (I of the (311) plane) 311 Integral strength (I) of the (222) plane for ) 222 The ratio of )(I 222 / I 311 A magnetic composite having ) 0.00 or more and 0.03 or less, wherein the ferrite layer has an α-Fe2O3 content of 0.1 mass% or more and 20.0 mass% or less. Claim 2 delete Claim 3 A magnetic composite according to claim 1, wherein the ferrite layer comprises iron (Fe) and oxygen (O) and comprises at least one element selected from the group consisting of lithium (Li), magnesium (Mg), aluminum (Al), titanium (Ti), manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), and cobalt (Co). Claim 4 In claim 1, the ferrite layer has a thickness (d F The ratio of surface arithmetic mean height (Sa) to ) (Sa / d F A magnetic composite in which ) is greater than 0.00 and less than or equal to 0.

20. Claim 5 In paragraph 3, the ferrite layer has a thickness (d F The ratio of surface arithmetic mean height (Sa) to ) (Sa / d F A magnetic composite in which ) is greater than 0.00 and less than or equal to 0.

20. Claim 6 A magnetic composite according to claim 1, wherein the ferrite layer comprises a ferrite constituent component and the remainder has a composition of unavoidable impurities. Claim 7 In paragraph 3, the magnetic composite, wherein the ferrite layer comprises a ferrite constituent and the remainder has a composition of unavoidable impurities. Claim 8 In claim 1, the specific gravity of the resin constituting the resin substrate is 0.95 g / cm³ 3 Ideal, magnetic complex. Claim 9 In paragraph 3, the specific gravity of the resin constituting the resin substrate is 0.95 g / cm³ 3 Ideal, magnetic complex. Claim 10 A magnetic composite according to claim 1, wherein the resin constituting the resin substrate is at least one selected from the group consisting of polycarbonate (PC), polyimide (PI), polyvinyl chloride (PVC), polyoxymethylene (POM), acrylonitrile butadiene styrene (ABS), polyetheretherketone (PEEK), and polyamide (PA).

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