Electromagnetic shielding materials, electronic components, and electronic equipment

Abstract

Provided are an electromagnetic-wave shielding material, an electronic component including the electromagnetic-wave shielding material, and an electronic apparatus, the electromagnetic-wave shielding material comprising a multilayer structure including two metal layers sandwiching a high-permeability layer which is an insulating layer having a complex relative permeability with the real part of more than or equal to 30 at a frequency of 100 kHz.

Description

[Technical Field]

[0001] This invention relates to electromagnetic shielding materials, electronic components, and electronic devices. [Background technology]

[0002] In recent years, electromagnetic shielding materials have attracted attention as materials for reducing the effects of electromagnetic waves in various electronic components and electronic devices (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 3-6898 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Electromagnetic shielding materials (hereinafter also referred to as "shielding materials") can perform the function of shielding electromagnetic waves (shielding performance) by reflecting electromagnetic waves incident on the shielding material and / or attenuating them within the shielding material.

[0005] "Electromagnetic waves" include both electric field waves and magnetic field waves. As an electromagnetic shielding material, one that can significantly attenuate both electric field waves and magnetic field waves is desirable because it can reduce the effects of both electric and magnetic field waves in electronic components and electronic equipment.

[0006] One aspect of the present invention aims to provide a novel electromagnetic shielding material that can exhibit high shielding performance against both electric and magnetic fields. [Means for solving the problem]

[0007] One aspect of the present invention is, An electromagnetic wave shielding material comprising a multilayer structure having a high-permeability layer between two metal layers, the high-permeability layer being an insulating layer with a real part of the complex relative permeability at a frequency of 100 kHz of 30 or more. Regarding.

[0008] In one embodiment, the high-permeability layer described above may contain magnetic particles.

[0009] In one embodiment, the magnetic particles may include metallic particles.

[0010] In one embodiment, the high-permeability layer may contain flattened particles as magnetic particles.

[0011] In one embodiment, the degree of orientation, which is the sum of the absolute value of the average orientation angle of the flattened particles with respect to the surface of the high-permeability layer and the variance of the orientation angle, can be 30° or less.

[0012] In one embodiment, the high-permeability layer may include a resin.

[0013] In one embodiment, the glass transition temperature Tg of the above resin can be 50°C or less.

[0014] In one embodiment, let T1 be the thickness of one of the two metal layers and T2 be the thickness of the other metal layer. T1 can be greater than or equal to T2, and the thickness ratio (T2 / T1) can be greater than or equal to 0.15.

[0015] In one embodiment, one or both of the two metal layers described above may be metal layers with a metal content of 80.0% by mass or more, selected from the group consisting of Al and Mg.

[0016] In one embodiment, the electromagnetic shielding material may further include one or more layers selected from the group consisting of adhesive layers and bonding layers.

[0017] In one embodiment, the total thickness of the metal layers included in the electromagnetic shielding material can be 100 μm or less.

[0018] In one form, the total thickness of the electromagnetic wave shielding material can be 200 μm or less.

[0019] One aspect of the present invention relates to an electronic component including the electromagnetic wave shielding material.

[0020] One aspect of the present invention relates to an electronic device including the electromagnetic wave shielding material. [Advantages of the Invention]

[0021] According to one aspect of the present invention, it is possible to provide a new electromagnetic wave shielding material that can exhibit high shielding performance against both electric field waves and magnetic field waves. Further, according to one aspect of the present invention, it is possible to provide an electronic component and an electronic device including this electromagnetic wave shielding material. [Embodiments for Carrying Out the Invention]

[0022] [Electromagnetic Wave Shielding Material] One aspect of the present invention relates to an electromagnetic wave shielding material including a multilayer structure having a high magnetic permeability layer that is an insulating layer having a real part of the complex relative magnetic permeability of 30 or more at a frequency of 100 kHz between two metal layers.

[0023] In the present invention and this specification, the "electromagnetic wave shielding material" refers to a material that can exhibit shielding performance against electromagnetic waves at at least one frequency or at least a part of a frequency band. "Electromagnetic waves" are classified into electric field waves and magnetic field waves. The "electromagnetic wave shielding material" is preferably a material that can exhibit shielding performance against both electric field waves at at least one frequency or at least a part of a frequency band and magnetic field waves at at least one frequency or at least a part of a frequency band, more preferably a material that can exhibit shielding performance against a wider frequency band of electric field waves and a wider frequency band of magnetic field waves, and even more preferably a material that can exhibit higher shielding performance.

[0024] When the complex relative permeability is measured using a permeability measuring device, the real part μ' and the imaginary part μ'' are usually displayed. In this invention and specification, the real part of the complex relative permeability refers to this real part μ'. Hereafter, the real part of the complex relative permeability at a frequency of 100 kHz will also be simply referred to as "permeability". Permeability can be measured using a commercially available permeability measuring device or a permeability measuring device with a known configuration.

[0025] In the present invention and this specification, "insulating properties" mean that the electrical conductivity is less than 1 S (siemens) / m. The electrical conductivity of a given layer is calculated from the surface electrical resistivity of that layer and the thickness of that layer by the following formula. Electrical conductivity can be measured by known methods. Electrical conductivity [S / m] = 1 / (Surface electrical resistivity [Ω] × Thickness [m])

[0026] The total thickness of the electromagnetic shielding material and the thickness of each layer contained within the electromagnetic shielding material shall be determined by imaging a cross-section exposed by a known method using a scanning electron microscope (SEM), and taking the arithmetic mean of the thicknesses of five randomly selected locations in the resulting SEM image.

[0027] In the present invention and this specification, "metal layer" means a layer containing a metal. A metal layer may be a layer containing one or more metals, such as a pure metal consisting of a single metal element, an alloy of two or more metal elements, or an alloy of one or more metal elements and one or more nonmetal elements. Details regarding the metal layer will be described later.

[0028] The inventors of the present invention speculate as follows on why the above-mentioned electromagnetic shielding material can exhibit high shielding performance against both electric and magnetic fields. However, the present invention is not limited to the speculation described herein.

[0029] The propagation constant γ and characteristic impedance Zs of a material when electromagnetic waves are incident on it can be expressed by the following equations. In the following equations, j is the imaginary unit, ω is the angular frequency of the electromagnetic wave [1 / s], μ is the permeability of the material [H / m], σ is the electrical conductivity of the material [S / m], and ε is the permittivity of the material [F / m].

[0030]

number

[0031] The propagation constant γ is related to the amplitude attenuation of electromagnetic waves in a material; the larger γ, the greater the attenuation of the electromagnetic wave amplitude. Comparing the metal layer with the high-permeability layer described above, σ is very large in the metal layer, so γ is also large. Therefore, significant attenuation of electromagnetic waves can be expected in the metal layer. In contrast, μ is large in the high-permeability layer, so γ is also large. Therefore, attenuation of electromagnetic waves can be expected in the high-permeability layer. On the other hand, in materials where μ, σ, and ε are all small, such as air and resin, the attenuation of electromagnetic waves within the material is very small. Furthermore, the characteristic impedance Zs is related to the reflectance and transmittance of electromagnetic waves when they enter and exit a material boundary. The greater the difference between the wave impedance and the characteristic impedance of the electromagnetic wave, the greater the reflection at the material boundary. In a metallic layer, σ is large and μ is small, so the characteristic impedance is small. In contrast, in the high-permeability layer mentioned above, μ is large, so σ is small and the characteristic impedance is large. At a sufficiently far distance from the wave source (for example, about 1 / 6 of the wavelength of the electromagnetic wave), the electromagnetic wave becomes a plane wave and its wave impedance is approximately 377Ω. On the other hand, at a sufficiently close distance from the wave source (for example, closer than 1 / 6 of the wavelength of the electromagnetic wave), the wave impedance decreases as you approach the source if the wave source is a small loop current (so-called magnetic field wave), and increases as you approach the source if the wave source is a small dipole (so-called electric field wave). In the KEC method, a typical method for measuring shielding performance, according to "Lumped-Parameter Equivalent Circuit of Electric Field / Magnetic Field Shielding Effect Measuring Instrument (KEC Method)" (Technical Report of the Institute of Image Information and Television Engineers, Vol. 25, 30 (2001)), the wave impedance at 100 kHz for magnetic field waves is 0.0033 Ω, which is significantly smaller than the wave impedance of a plane wave (377 Ω). KEC is an abbreviation for the Kansai Electronics Industry Promotion Center. Thus, because the wave impedance of a magnetic field wave is small, when a magnetic field wave is incident on and off a metal layer with low characteristic impedance, the difference between the wave impedance and characteristic impedance is small, resulting in low reflectivity at the interface. On the other hand, when a magnetic field wave is incident on and off the high-permeability layer with high characteristic impedance, the difference between the wave impedance and characteristic impedance is large, resulting in higher reflectivity at the interface than in the metal layer. In order to obtain high shielding performance against electromagnetic waves in an electromagnetic shielding material, it is desirable to increase the reflection at the interface in addition to increasing the electromagnetic wave attenuation capacity. That is, it is desirable for electromagnetic waves to be greatly attenuated by repeatedly reflecting at the interface and passing through the shielding material many times. However, as described above, regarding the behavior of the metal layer and the high permeability layer with respect to electromagnetic waves, the metal layer has a large electromagnetic wave attenuation capacity but small reflection of magnetic field waves at the interface, while the high permeability layer has a smaller electromagnetic wave attenuation capacity than the metal layer but greater reflection of magnetic field waves at the interface than the metal layer. Therefore, it is difficult to achieve both high reflection and attenuation against magnetic field waves with the metal layer alone or the high permeability layer alone. In contrast, the electromagnetic shielding material described above includes a multilayer structure having the high-permeability layer between two metal layers, thereby achieving both reflection of electromagnetic waves at the interface and attenuation of electromagnetic waves within the layers. The inventors believe this is the reason why the electromagnetic shielding material can exhibit high shielding performance against both electric and magnetic fields.

[0032] The electromagnetic shielding material described above will be explained in more detail below.

[0033] <High permeability layer> The permeability (real part of the complex ratio permeability at a frequency of 100 kHz) of the above-mentioned high-permeability layer is 30 or higher. Including an insulating layer with a high permeability of 30 or higher between the two metal layers can contribute to the electromagnetic shielding material exhibiting high shielding performance not only against electric fields but also against magnetic fields. From this point of view, the permeability is preferably 40 or higher, more preferably 50 or higher, even more preferably 60 or higher, even more preferably 70 or higher, even more preferably 80 or higher, even more preferably 90 or higher, and still even more preferably 100 or higher. Furthermore, the permeability can be, for example, 200 or less, 190 or less, 180 or less, 170 or less, or 160 or less, and can exceed the values ​​exemplified here. A higher permeability is preferable because it increases the characteristic impedance Zs and allows for a higher interfacial reflection effect.

[0034] The above-mentioned high-permeability layer is an insulating layer. This also contributes to the fact that the electromagnetic shielding material can exhibit high shielding performance not only against electric field waves but also against magnetic field waves. The electrical conductivity of the above-mentioned high-permeability layer is less than 1 S / m, preferably 0.5 S / m or less, more preferably 0.1 S / m or less, and even more preferably 0.05 S / m or less. The electrical conductivity of the above-mentioned high-permeability layer is, for example, 1.0 × 10⁻⁶ -12 S / m or larger or 1.0×10 -10 It can be S / m or higher.

[0035] (magnetic particles) The above-mentioned high-permeability layer may contain magnetic particles. In the present invention and this specification, "magnetic" means ferromagnetic property. As magnetic particles, one type selected from the group consisting of magnetic particles generally called soft magnetic particles, such as metal particles and ferrite particles, or a combination of two or more types can be used. Since metal particles generally have a saturation magnetic flux density about 2 to 3 times that of ferrite particles, they can maintain relative permeability without magnetic saturation even under a strong magnetic field and exhibit shielding performance. Therefore, it is preferable that the magnetic particles contained in the high-permeability layer are metal particles.

[0036] metal particles In the present invention and this specification, "metal particles" include particles of pure metals consisting of a single metal element, and particles of alloys of one or more metal elements with one or more other metal and / or nonmetal elements. The metal particles may or may not be crystalline. That is, metal particles may be crystalline particles or amorphous particles. Examples of metallic or nonmetallic elements contained in metal particles include Ni, Fe, Co, Mo, Cr, Al, Si, B, P, etc. Metal particles may or may not contain components other than the constituent elements of the metal (including alloys). In addition to the constituent elements of the metal (including alloys), metal particles may contain in any proportion elements contained in additives that may be optionally added and / or elements contained in impurities that may be unintentionally introduced during the manufacturing process of the metal particles. In metal particles, the content of constituent elements of the metal (including alloys) is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, and may also be 100% by mass, less than 100% by mass, 99.9% by mass or less, or 99.0% by mass or less.

[0037] Examples of metal particles include Sendust (Fe-Si-Al alloy), Permalloy (Fe-Ni alloy), Molybdenum Permalloy (Fe-Ni-Mo alloy), Fe-Si alloy, Fe-Cr alloy, Fe-containing alloys generally called iron-based amorphous alloys, Co-containing alloys generally called cobalt-based amorphous alloys, alloys generally called nanocrystalline alloys, iron, and Permendur (Fe-Co alloy). Among these, Sendust is preferred because it exhibits high saturation magnetic flux density and relative permeability.

[0038] Flat shaped particles From the viewpoint of forming a layer that exhibits high permeability as a high-permeability layer, it is preferable that the magnetic particles are flattened particles. By arranging the long side direction of the flattened particles to be closer to parallel with the in-plane direction of the high-permeability layer, the long side direction of the particles is more aligned with the vibration direction of electromagnetic waves incident perpendicular to the electromagnetic wave shielding material, thereby reducing the demagnetizing field and allowing for higher permeability. In the present invention and this specification, "flattened particles" refers to particles with an aspect ratio of 0.20 or less. The aspect ratio of the flattened particles is preferably 0.15 or less, and more preferably 0.10 or less. The aspect ratio of the flattened particles can be, for example, 0.01 or more, 0.02 or more, or 0.03 or more. For example, the shape of the particles can be made flattened by flattening by a known method. For information on flattening, see, for example, Japanese Patent Publication No. 2018-131640, specifically paragraphs 0016, 0017, and the section on examples. The magnetic particles contained in the high-permeability layer are preferably flattened Sendust particles.

[0039] As described above, from the viewpoint of forming a layer exhibiting high permeability as a high-permeability layer, it is preferable to arrange the flattened particles so that the direction of the long side is closer to parallel with the in-plane direction of the high-permeability layer. From this point of view, the degree of orientation, which is the sum of the absolute value of the average orientation angle of the flattened particles with respect to the surface of the high-permeability layer and the variance of the orientation angle, is preferably 30° or less, more preferably 25° or less, even more preferably 20° or less, and most preferably 15° or less. The degree of orientation can be, for example, 3° or more, 5° or more, or 10° or more, and can also be lower than the values ​​exemplified here. The method for controlling the degree of orientation will be described later.

[0040] In the present invention and this specification, the aspect ratio and the degree of orientation of the magnetic particles shall be determined by the following method. The cross-section of the high-permeability layer is exposed by a known method. A cross-sectional image is acquired as a SEM image of a randomly selected region of this cross-section. The imaging conditions are: acceleration voltage: 2kV, magnification: 1000x, and the SEM image is obtained as a backscattered electron image. The image is read in grayscale using the cv2.imread() function of the OpenCV4 image processing library (Intel Corporation) with the second argument set to 0. A binarized image is obtained using the cv2.threshold() function, with the midpoint between the high-luminance and low-luminance areas as the boundary. The white areas (high-luminance areas) in the binarized image are identified as magnetic particles. For the obtained binarized image, the rotational circumscribed rectangle corresponding to the portion of each magnetic particle is obtained using the cv2.minAreaRect() function, and the long side length, short side length, and rotation angle are obtained as the return value of the cv2.minAreaRect() function. When determining the total number of magnetic particles included in the above binarized image, particles in which only a portion is included in the binarized image shall be included. For particles in which only a portion is included in the binarized image, the long side length, short side length, and rotation angle are determined for the portion included in the binarized image. The ratio of the short side length to the long side length (short side length / long side length) obtained in this way shall be taken as the aspect ratio of each magnetic particle. In the present invention and this specification, if the number of magnetic particles identified as flattened particles with an aspect ratio of 0.20 or less is 10% or more of the total number of magnetic particles included in the above binarized image on a numerical basis, then the high permeability layer shall be determined to be a "high permeability layer containing flattened particles as magnetic particles". Furthermore, the "orientation angle" is determined from the rotation angle obtained above, as the rotation angle with respect to the horizontal plane (the surface of the high-permeability layer). Particles with an aspect ratio of 0.20 or less obtained in the binarized image are identified as flattened particles. For the orientation angles of all flattened particles included in the binarized image, the sum of the absolute value of the mean (arithmetic mean) and the variance is calculated. This sum is defined as the "orientation degree". Furthermore, the coordinates of the circumscribing rectangle are calculated using the cv2.boxPoints() function, and an image is created by superimposing the rotated circumscribing rectangle onto the original image using the cv2.drawContours() function. Rotated circumscribing rectangles that are clearly misdetected are excluded from the calculation of the aspect ratio and orientation degree. In addition, the mean (arithmetic mean) of the aspect ratios of the particles identified as flattened particles is defined as the aspect ratio of flattened particles included in the high-permeability layer of the measurement target. This aspect ratio is 0.20 or less, preferably 0.15 or less, and more preferably 0.10 or less. The above aspect ratio can also be, for example, 0.01 or more, 0.02 or more, or 0.03 or more.

[0041] The magnetic particle content in the above-mentioned high-permeability layer can be, for example, 50% or more by mass, 60% or more by mass, 70% or more by mass, 72% or more by mass, 75% or more by mass, or 80% or more by mass, relative to the total mass of the high-permeability layer, and can also be, for example, 100% or less by mass, 98% or less by mass, or 95% or less by mass.

[0042] As a high-permeability layer, one embodiment can be a sintered body of ferrite particles (ferrite plate), etc. Considering that electromagnetic wave shielding material may need to be cut to a desired size or be bent into a desired shape, a layer containing resin is preferred as the high-permeability layer compared to a sintered ferrite plate.

[0043] (resin) The high-permeability layer may be a layer containing resin, or a layer containing magnetic particles and resin. In a high-permeability layer containing magnetic particles and resin, the resin content may be, for example, 1 part by mass or more, 3 parts by mass or more, or 5 parts by mass or more per 100 parts by mass of magnetic particles, or 20 parts by mass or less, or 15 parts by mass or less.

[0044] Resins can act as binders in high-permeability layers. In the present invention and this specification, "resin" means polymer, and includes rubber and elastomers. Polymers include homopolymers and copolymers. Rubbers include natural rubber and synthetic rubber. Elastomers are polymers that exhibit elastic deformation. Examples of resins include conventionally known thermoplastic resins, thermosetting resins, UV-curable resins, radiation-curable resins, rubber-based materials, and elastomers. Specific examples include polyester resins, polyethylene resins, polyvinyl chloride resins, polyvinyl butyral resins, polyurethane resins, cellulose resins, ABS (acrylonitrile-butadiene-styrene) resins, nitrile-butadiene rubbers, styrene-butadiene rubbers, epoxy resins, phenolic resins, amide resins, styrene elastomers, olefin elastomers, vinyl chloride elastomers, polyester elastomers, polyamide elastomers, polyurethane elastomers, and acrylic elastomers.

[0045] The electromagnetic wave shielding material described above can be used, for example, by bending it into any shape. When the shielding material is bent, if the high permeability layer breaks, the shielding performance may decrease at the point of breakage. Therefore, a high permeability layer that is highly resistant to breakage and difficult to break when bent is desirable. From the viewpoint of improving the break resistance of the high permeability layer, a layer containing a resin with a glass transition temperature Tg of 50°C or less is preferred as the high permeability layer. In the present invention and this specification, the glass transition temperature Tg is determined from the measurement results of heat flow measurement using a differential scanning calorimeter as the baseline shift start temperature of the heat flowchart when heating. From the viewpoint of further improving the break resistance of the high permeability layer, the glass transition temperature Tg of the resin contained in the high permeability layer is more preferably 40°C or less, even more preferably 30°C or less, even more preferably 20°C or less, even more preferably 10°C or less, even more preferably 0°C or less, and even more preferably -10°C or less. The glass transition temperature Tg of the resin contained in the high permeability layer can be, for example, -100°C or higher, -90°C or higher, or -80°C or higher.

[0046] In addition to the above components, the high-permeability layer may also contain one or more known additives such as curing agents, dispersants, stabilizers, and coupling agents in any amount.

[0047] <Metal layer> The electromagnetic shielding material described above includes the high-permeability layer between two metal layers. The electromagnetic shielding material may include one or more multilayer structures having the high-permeability layer between two metal layers. That is, the electromagnetic shielding material may include at least two metal layers, and may include three or more metal layers, and may include at least one high-permeability layer, and may include two or more high-permeability layers. In one embodiment, the two or three or more metal layers included in the electromagnetic shielding material have the same composition and thickness, and in another embodiment, they have different compositions and / or thicknesses. Furthermore, if the electromagnetic shielding material includes two or more high-permeability layers, in one embodiment, the two or more high-permeability layers have the same composition and thickness, and in another embodiment, they have different compositions and / or thicknesses.

[0048] Specific examples of the layer configuration of the electromagnetic shielding material described above include "metal layer / high permeability layer / metal layer", "metal layer / high permeability layer / metal layer / high permeability layer / metal layer", and "metal layer / high permeability layer / metal layer / high permeability layer / metal layer / high permeability layer / metal layer / high permeability layer / metal layer". In the above, the symbol " / " is used to encompass both the case where the layer listed to the left of the symbol and the layer listed to the right are in direct contact without other layers in between, and the case where they are indirectly laminated through one or more other layers. Specific examples of the other layers described above include double-sided tape and adhesives for bonding, which will be discussed later.

[0049] As the metal layer, a layer containing one or more metals selected from the group consisting of various pure metals and various alloys can be used. The metal layer can exert an attenuation effect in the shielding material. The attenuation effect is greater the larger the propagation constant, and the propagation constant is greater the larger the electrical conductivity; therefore, it is preferable that the metal layer contains a metal element with high electrical conductivity. From this point of view, it is preferable that the metal layer contains a pure metal of Ag, Cu, Au, or Al, or an alloy in which one of these is the main component. A pure metal is a metal consisting of a single metal element and may contain trace amounts of impurities. Generally, a metal consisting of a single metal element with a purity of 99.0% or more is called a pure metal. Purity is based on mass. An alloy is generally a pure metal with one or more metal or non-metal elements added to adjust its composition for purposes such as corrosion prevention and strength improvement. The main component in an alloy is the component with the highest proportion by mass, and can be, for example, a component that accounts for 80.0% by mass or more (for example, 99.8% by mass or less) in the alloy. From an economic standpoint, pure metals of Cu or Al, or alloys mainly composed of Cu or Al, are preferred, and from the standpoint of high electrical conductivity, pure metals of Cu or alloys mainly composed of Cu are more preferred.

[0050] The purity of the metal in the metal layer, i.e., the metal content, can be 99.0% by mass or more, preferably 99.5% by mass or more, and more preferably 99.8% by mass or more, relative to the total mass of the metal layer. Unless otherwise specified, the metal content in the metal layer refers to the content on a mass basis. For example, as the metal layer, a sheet of pure metal or alloy can be used. For example, pure metal Cu is commercially available in sheets of various thicknesses (so-called copper foil). For example, such copper foil can be used as the metal layer. Copper foil includes electrolytic copper foil obtained by depositing copper foil on the cathode by electroplating, and rolled copper foil obtained by applying heat and pressure to an ingot and stretching it thinly. Either type of copper foil can be used as the metal layer of the electromagnetic shielding material described above. Also, for example, Al is commercially available in sheets of various thicknesses (so-called aluminum foil). For example, such aluminum foil can be used as the metal layer.

[0051] From the viewpoint of reducing the weight of electromagnetic shielding materials, it is preferable that one or both (preferably both) of the two metal layers included in the above multilayer structure are metal layers containing a metal selected from the group consisting of Al and Mg. This is because both Al and Mg have small values ​​obtained by dividing specific gravity by electrical conductivity (specific gravity / electrical conductivity). The smaller this value of the metal used, the lighter the electromagnetic shielding material can be while maintaining high shielding performance. As values ​​calculated from literature, for example, the values ​​obtained by dividing specific gravity by electrical conductivity (specific gravity / electrical conductivity) for Cu, Al, and Mg are as follows: Cu: 1.5 × 10 -7 m / s, Al: 7.6 × 10 -8 m / s, Mg: 7.6 × 10 -8m / S. From the above values, Al and Mg can be said to be preferred metals from the viewpoint of reducing the weight of the electromagnetic shielding material. A metal layer containing a metal selected from the group consisting of Al and Mg may, in one form, contain only Al or Mg, and in another form, contain both. From the viewpoint of reducing the weight of the electromagnetic shielding material, it is more preferable that one or both (preferably both) of the two metal layers included in the above multilayer structure have a metal content of 80.0 mass% or more of a metal selected from the group consisting of Al and Mg, and even more preferable that they have a metal content of 90.0 mass% or more of a metal selected from the group consisting of Al and Mg. A metal layer containing at least Al among Al and Mg may have an Al content of 80.0 mass% or more, and may also have an Al content of 90.0 mass% or more. A metal layer containing at least Mg among Al and Mg may have an Mg content of 80.0 mass% or more, and may also have an Mg content of 90.0 mass% or more. The content of the metal selected from the group consisting of Al and Mg, the Al content, and the Mg content can each be, for example, 99.9% by mass or less. The content of the metal selected from the group consisting of Al and Mg, the Al content, and the Mg content are each the content relative to the total mass of the metal layer.

[0052] <Various thicknesses> From the viewpoint of processability of the metal layer and the shielding performance of the electromagnetic wave shielding material, the thickness of the metal layer is preferably 4 μm or more per layer, more preferably 5 μm or more, even more preferably 10 μm or more, even more preferably 15 μm or more, even more preferably 20 μm or more, and even more preferably 25 μm or more. On the other hand, from the viewpoint of processability of the metal layer, the thickness of the metal layer is preferably 100 μm or less per layer, more preferably 50 μm or less, even more preferably 45 μm or less, and even more preferably 40 μm or less.

[0053] If we consider two metal layers separated by a high-permeability layer, and let T1 be the thickness of one metal layer and T2 be the thickness of the other metal layer, and T1 is greater than or equal to T2 (i.e., T1 = T2 or T1 > T2), then the ratio of the thicknesses of the two metal layers (T2 / T1) can be, for example, 0.10 or more. From the viewpoint of being able to show higher shielding performance against magnetic field waves, it is preferable that it be 0.15 or more, more preferably 0.30 or more, even more preferably 0.50 or more, even more preferably 0.70 or more, and even more preferably 0.80 or more. From the viewpoint of being able to show even higher shielding performance against magnetic field waves, it is preferable that the difference between T1 and T2 is smaller. The ratio of the thicknesses (T2 / T1) can be 1.00 or less, and can also be 1.00 (i.e., T1 = T2). If the electromagnetic shielding material described above includes two or more multilayer structures having the high permeability layer between two metal layers, the above description regarding the thickness ratio (T2 / T1) can be applied to at least one of the multilayer structures included in the electromagnetic shielding material, to two or more, or to all of them.

[0054] Shielding material can be bent and processed into any shape according to its application. When the shielding material is bent, if the width of the bent portion (hereinafter referred to as "bending width") is wide, the shape of the bent portion becomes a gentle curve, which may make it difficult to process into the desired shape. From this point of view, the narrower the bending width, the better; for example, it is preferable to have a bending width of 2.20 mm or less, 2.00 mm or less, and more preferably 1.50 mm or less. The thicker the total thickness of the metal layers contained in the shielding material, the wider the bending width tends to be. From the viewpoint of narrowing the bending width of the shielding material, the total thickness of the metal layers contained in the electromagnetic wave shielding material is preferably 100 μm or less, more preferably 90 μm or less, even more preferably 80 μm or less, even more preferably 70 μm or less, even more preferably 60 μm or less, even more preferably 50 μm or less, and still even more preferably 40 μm or less. The total thickness of the metal layers contained in the electromagnetic wave shielding material can be, for example, 8 μm or more or 10 μm or more. The total number of metal layers in the electromagnetic shielding material described above is two or more, and can be, for example, 2 to 5 layers.

[0055] Regarding the thickness of the high permeability layer described above, the thickness per layer can be, for example, 3 μm or more, preferably 10 μm or more, and more preferably 20 μm or more, from the viewpoint of the shielding performance of the electromagnetic wave shielding material. Furthermore, from the viewpoint of the processability of the electromagnetic wave shielding material, the thickness per layer of the high permeability layer can be, for example, 90 μm or less, preferably 70 μm or less, and more preferably 50 μm or less. When the electromagnetic wave shielding material contains two or more layers of the high permeability layer described above, the total thickness of the high permeability layers contained in the electromagnetic wave shielding material can be, for example, 6 μm or more, and also, for example, 180 μm or less. The total number of layers of the high permeability layer contained in the electromagnetic wave shielding material can be one or more, and can be, for example, 1 to 4 layers.

[0056] Furthermore, the total thickness of the shielding material can be, for example, 250 μm or less. From the viewpoint of narrowing the bending width, a thinner total thickness of the shielding material is also preferable. From this point of view, the total thickness of the electromagnetic wave shielding material is preferably 200 μm or less, more preferably 190 μm or less, and even more preferably 170 μm or less. The total thickness of the electromagnetic wave shielding material can be, for example, 30 μm or more or 40 μm or more.

[0057] <Manufacturing method for electromagnetic wave shielding material> (Method for forming a high-permeability layer) The above-mentioned high-permeability layer can be produced, for example, by applying a high-permeability layer-forming composition and drying the resulting coating layer. The high-permeability layer-forming composition contains the components described above and may optionally contain one or more solvents. Examples of solvents include various organic solvents, such as ketone solvents like acetone, methyl ethyl ketone, and cyclohexanone; acetic acid ester solvents like ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols like cellosolve and butyl carbitol; aromatic hydrocarbon solvents like toluene and xylene; and amide solvents like dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. One solvent selected considering the solubility of the components used in the preparation of the high-permeability layer-forming composition, or two or more solvents mixed in any proportion, can be used. The solvent content of the high-permeability layer-forming composition is not particularly limited and should be determined considering the coatability of the high-permeability layer-forming composition.

[0058] Compositions for forming high magnetic permeability layers can be prepared by mixing various components sequentially or simultaneously in any order. Furthermore, if necessary, dispersion can be performed using known dispersers such as ball mills, bead mills, sand mills, and roll mills, and / or stirring can be performed using known stirrers such as shaking stirrers.

[0059] The high-permeability layer-forming composition can be applied, for example, to a support. The application can be carried out using known application equipment such as a blade coater or die coater. The application can be performed using a so-called roll-to-roll method or a batch method.

[0060] Examples of supports to which the high-permeability layer-forming composition is applied include films of various resins such as polyester (PET, PEN, etc.), polycarbonate (PC), acrylic (PMMA, etc.), cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. For these resin films, refer to paragraphs 0081 to 0086 of Japanese Patent Application Publication No. 2015-187260. As the support, a support that has been subjected to a release treatment by a known method on the surface (coated surface) to which the high-permeability layer-forming composition is applied can be used. One form of the release treatment is the formation of a release layer. For the release layer, refer to paragraph 0084 of Japanese Patent Application Publication No. 2015-187260. Alternatively, commercially available pre-released resin films can be used as the support. By using a support with a stripping treatment applied to the surface to be coated, the high-permeability layer and the support can be easily separated after film formation.

[0061] In one embodiment, a metal layer is used as a support, and the composition for forming a high magnetic permeability layer is directly applied onto the metal layer. By directly applying the composition for forming a high magnetic permeability layer onto the metal layer, a laminated structure of a metal layer and a high magnetic permeability layer can be manufactured in a single step.

[0062] The coating layer formed by applying the high-permeability layer-forming composition can be dried by known methods such as heating or blowing hot air. The drying process can be carried out under conditions that allow the solvent contained in the high-permeability layer-forming composition to volatilize. For example, the drying process can be carried out in a heated atmosphere with an ambient temperature of 80 to 150°C for 1 minute to 2 hours.

[0063] The degree of orientation of the flattened particles described above can be controlled by the type of solvent, amount of solvent, viscosity, and coating thickness of the high-permeability layer-forming composition. For example, if the boiling point of the solvent is low, convection occurs due to drying, which tends to increase the degree of orientation. If the amount of solvent is low, physical interference between adjacent flattened particles tends to increase the degree of orientation. On the other hand, if the viscosity is low, rotation of the flattened particles is more likely to occur, which tends to decrease the degree of orientation. Reducing the coating thickness tends to decrease the degree of orientation. Furthermore, pressurizing treatment, which will be described later, can contribute to reducing the degree of orientation. By adjusting the various manufacturing conditions described above, the degree of orientation of the flattened particles can be controlled within the range described above.

[0064] (Pressurization treatment of high-permeability layer) High-permeability layers can also be subjected to pressure treatment after film formation. By applying pressure to a high-permeability layer containing magnetic particles, the density of magnetic particles within the layer can be increased, resulting in higher permeability. Furthermore, in high-permeability layers containing flattened particles, the degree of orientation can be reduced by pressure treatment, resulting in higher permeability.

[0065] Pressurization can be performed by applying pressure in the thickness direction of the high-permeability layer using a flat plate press, a roll press, or the like. A flat plate press places the object to be pressed between two flat press plates positioned vertically, and applies pressure to the object by bringing the two press plates together using mechanical or hydraulic pressure. A roll press passes the object to be pressed between rotating pressure rolls positioned vertically, and applies pressure by applying mechanical or hydraulic pressure to the pressure rolls during this process, or by making the distance between the pressure rolls smaller than the thickness of the object to be pressed.

[0066] The pressure during pressurization can be set arbitrarily. For example, in the case of a flat plate press, it can be set to 1-50 N (Newtons) / mm 2 For example, in the case of a roll press machine, the linear pressure is 20-400 N / mm. The pressurization time can be set arbitrarily. When using a flat plate press, for example, it can be from 5 seconds to 30 minutes. When using a roll press, the pressurization time can be controlled by the conveying speed of the object being pressed, for example, the conveying speed can be from 10 cm / min to 200 m / min. The material of the press plate and pressure roll can be arbitrarily selected from metal, ceramics, plastic, rubber, etc. During the pressurization process, it is also possible to apply heat to both the upper and lower press plates of a plate press machine, or to one of the upper and lower rolls of a roll press machine, and then apply pressure. Heating can soften the high-permeability layer, thereby achieving a high compression effect when pressure is applied. The heating temperature can be set arbitrarily, for example, between 50°C and 200°C. The above heating temperature can be the internal temperature of the press plate or roll. This temperature can be measured by a thermometer installed inside the press plate or roll. After heating and pressurizing in a plate press, for example, the high-permeability layer can be extracted by separating the press plates while they are still hot. Alternatively, the high-permeability layer can be extracted by cooling the press plates with water, air, or other methods while maintaining the pressure, and then separating the press plates. In a roll press machine, the high-permeability layer can be cooled immediately after pressing by methods such as water cooling or air cooling. It is also possible to repeat the pressurization process two or more times. When a high-permeability layer is deposited on a release film, for example, it can be subjected to pressure treatment while laminated on the release film. Alternatively, it can be peeled off the release film and subjected to pressure treatment as a single layer of high-permeability layer. When a high-permeability layer is deposited directly on a metal layer, it can be subjected to pressure treatment while the metal layer and the high-permeability layer are stacked together. Furthermore, by performing pressure treatment with the high-permeability layer positioned between metal layers, it is possible to simultaneously perform pressure treatment on the high-permeability layer and bond the metal layer and the high-permeability layer.

[0067] (Bonding of a metal layer and a high-permeability layer) A metal layer and a high-permeability layer can be directly bonded together, for example, by applying pressure and heat. A flat plate press, roll press, etc., can be used for bonding. During the bonding process, the high-permeability layer softens, promoting contact with the metal layer surface, thereby bonding the metal layer and the high-permeability layer. The pressure during bonding can be set arbitrarily. For a flat plate press, for example, 1 to 50 N / mm². 2 For a roll press, the linear pressure is, for example, 20 to 400 N / mm. The pressing time during crimping can be set arbitrarily. When using a flat plate press, for example, it is 5 seconds to 30 minutes. When using a roll press, it can be controlled by the conveying speed of the object to be pressed, for example, the conveying speed is 10 cm / min to 200 m / min. The temperature during crimping can be selected arbitrarily. For example, it is 50°C or higher and 200°C or lower.

[0068] The metal layer and the high-permeability layer can also be bonded together by interposing an adhesive layer and / or bonding layer between the metal layer and the magnetic layer.

[0069] In the present invention and this specification, "adhesive layer" refers to a layer that has tackiness on its surface at room temperature. Here, "room temperature" refers to 23°C, and the room temperature described later with respect to the adhesive layer also refers to 23°C. Such a layer adheres to an object by its adhesive force when it comes into contact with the object. Tackiness generally refers to the property of exhibiting adhesive force in a short time after contact with an object with very light force, and in the present invention and this specification, "having tackiness" means that the result in the inclined ball tack test specified in JIS Z 0237:2009 (measurement environment: temperature 23°C, relative humidity 50%) is No. 1 to No. 32. If other layers are laminated on the surface of the adhesive layer, for example, the surface of the adhesive layer exposed by peeling off the other layers can be subjected to the above test. If other layers are laminated on one surface and the other surface of the adhesive layer, the other layers on either surface can be peeled off.

[0070] As the adhesive layer, a film can be used which has been processed by coating it with an adhesive-forming composition containing an adhesive such as an acrylic adhesive, a rubber adhesive, a silicone adhesive, or a urethane adhesive. The adhesive layer-forming composition can be applied, for example, to a support. The application can be carried out using known application equipment such as a blade coater or die coater. The application can be performed using a so-called roll-to-roll method or a batch method. Examples of supports to which the adhesive layer-forming composition is applied include films of various resins such as polyester (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN)), polycarbonate (PC), acrylic (e.g., polymethyl methacrylate (PMMA)), cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. As the support, a support that has been subjected to a release treatment by a known method on the surface to which the adhesive layer-forming composition is applied (the surface to be coated) can be used. One form of release treatment is the formation of a release layer. Alternatively, commercially available pre-released resin films can be used as the support. By using a support with a release treatment on the surface to be coated, the adhesive layer and the support can be easily separated after film formation. An adhesive layer can be laminated onto the surface of a metal layer or a high-permeability layer by coating an adhesive layer-forming composition, in which the adhesive is dissolved and / or dispersed in a solvent, onto the metal layer or high-permeability layer and drying it.

[0071] Furthermore, by overlapping a film-like adhesive layer with a metal layer or a high-permeability layer and applying pressure, the adhesive layer can be laminated onto the surface of the metal layer or high-permeability layer.

[0072] To fabricate an electromagnetic shielding material having an adhesive layer, an adhesive tape containing the adhesive layer can be used. Double-sided tape can be used as the adhesive tape. Double-sided tape has adhesive layers on both sides of a support, and both adhesive layers may have tackiness at room temperature. Alternatively, an adhesive tape with an adhesive layer on one side of the support can be used. Examples of support materials include films, nonwoven fabrics, and paper made from various resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. Commercially available adhesive tapes with adhesive layers on one or both sides of the support can be used, as can double-sided tapes manufactured by known methods.

[0073] In the present invention and this specification, "adhesive layer" means a layer that has no tackiness on its surface at room temperature, and which, when heated and pressed against an adherend, flows and follows minute irregularities on the adherend surface, exhibiting adhesive force through an anchoring effect, or, when heated and pressed against an adherend, forms a chemical bond with the adherend surface through a chemical reaction, thereby exhibiting adhesive force. The adhesive layer can soften and / or undergo a chemical reaction upon heating. The above-mentioned "no tackiness" means that in the inclined ball tack test specified in JIS Z 0237:2009 (measurement environment: temperature 23°C, relative humidity 50%), ball No. 1 does not stop. If other layers are laminated on the surface of the adhesive layer, for example, the adhesive layer surface exposed by peeling off the other layers can be subjected to the above test. If other layers are laminated on one surface and the other surface of the adhesive layer, the other layers on either surface can be peeled off.

[0074] A film-like resin material can be used as the adhesive layer. Thermoplastic resins and / or thermosetting resins can be used as the resin material. Thermoplastic resins have the property of softening when heated, and when pressed against the adherend while heated, they flow and conform to minute irregularities on the adherend surface, exhibiting adhesive strength through an anchoring effect. The adhesive state can then be maintained by cooling. Thermosetting resins can undergo a chemical reaction when heated, and when heated in contact with the adherend, a chemical reaction occurs, forming a chemical bond with the adherend surface and exhibiting adhesive strength.

[0075] Examples of thermoplastic resins include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyvinyl acetate, polyurethane, polyvinyl alcohol, ethylene vinyl acetate copolymer, styrene-butadiene rubber, acrylonitrile-butadiene rubber, silicone rubber, olefin-based elastomers (PP), styrene-based elastomers, ABS resin, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polycarbonate (PC), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, and triacetylcellulose (TAC). Examples of thermosetting resins include epoxy resins, phenolic resins, melamine resins, thermosetting urethane resins, xylene resins, and thermosetting silicone resins. It is preferable in terms of adhesion between the high-permeability layer and the adhesive layer if the adhesive layer contains a resin whose main polymer skeleton is similar to that of the resin contained in the high-permeability layer, as this increases the compatibility between the resin in the high-permeability layer and the resin in the adhesive layer. For example, it is preferable that both the high-permeability layer and the adhesive layer contain polyurethane resin.

[0076] The film-like resin material used as the adhesive layer may be a commercially available product or a film-like resin material prepared by a known method.

[0077] In one embodiment, an adhesive layer made of a film-like resin material can be laminated onto the surface of a metal layer or high-permeability layer by coating a resin or resin precursor dissolved and / or dispersed in a solvent onto a metal layer or high-permeability layer and curing it by drying or polymerization. Alternatively, an adhesive layer can be formed by coating a support with a resin or resin precursor dissolved and / or dispersed in a solvent, curing it by drying or polymerization, and then peeling it off the support to form a film-like adhesive layer.

[0078] By layering a film-like adhesive layer with a metal layer or a high-permeability layer and applying pressure under heating, the adhesive layer can be laminated onto the surface of the metal layer or high-permeability layer. By heating and applying pressure while the highly permeable layer, which is the object to be adhered to, is superimposed on the adhesive layer of a metal layer that has an adhesive layer laminated on its surface, the metal layer and the highly permeable layer can be bonded together via the adhesive layer. Alternatively, the metal layer to be adhered to can be bonded to the high-permeability layer via the adhesive layer by overlapping the metal layer with the adhesive layer of the high-permeability layer, which has an adhesive layer laminated on its surface, and then applying pressure under heating. Alternatively, the metal layer and the high-permeability layer can be bonded together via the adhesive layer by overlapping them with an adhesive layer, which is a film-like resin material, between them, and then applying pressure under heating. Pressurization under heating can be performed using a flat plate press, roll press, or the like, which have a heating mechanism.

[0079] Furthermore, as an example of an adhesive means, we can also mention the double-sided tape described in Japanese Patent Publication No. 2003-20453 as a silicone-based substrate-less double-sided tape.

[0080] General adhesive and bonding layers have extremely low electrical conductivity compared to metal layers, extremely low magnetic permeability compared to the high-permeability layers mentioned above, and a relative permittivity only a few times that of air, with characteristic impedance and propagation constants similar to those of air. Therefore, using general adhesive and / or bonding layers does not affect the shielding performance of the shielding material, or the effect is negligibly small. The thickness of each adhesive and bonding layer is not particularly limited and can be, for example, between 1 μm and 30 μm.

[0081] In one embodiment, the electromagnetic shielding material described above can be manufactured by following one or more of the following steps. However, the manufacturing method of the electromagnetic shielding material is not particularly limited.

[0082] The metal layer and the high-permeability layer are bonded together using an adhesive or bonding layer formed in the form of a film.

[0083] The bonding of the metal layer and the high-permeability layer is performed by forming a high-permeability layer with an adhesive or bonding layer on its surface, and then bonding this high-permeability layer to the metal layer via the adhesive or bonding layer.

[0084] The bonding of the metal layer and the high-permeability layer is performed by forming a metal layer with an adhesive or bonding layer on its surface, and then bonding this metal layer to the high-permeability layer via the adhesive or bonding layer.

[0085] The adhesive layer or bonding layer is directly coated onto the surface of the metal layer or high-permeability layer.

[0086] A high-permeability layer having an adhesive or bonding layer on its surface is formed by coating a release film with an adhesive or bonding layer, applying pressure to bond it to a high-permeability layer, or applying heat and pressure to bond it to a high-permeability layer, and then peeling off the release film.

[0087] A metal layer having an adhesive or bonding layer on its surface is formed by coating a release film with an adhesive or bonding layer, applying pressure to bond it to a high-permeability layer, or applying heat and pressure to bond it to a metal layer, and then peeling off the release film.

[0088] The electromagnetic shielding material described above can be in any shape and size, such as a film (or sheet). For example, a film-like electromagnetic shielding material can be bent into any shape and incorporated into electronic components or electronic devices.

[0089] [Electronic components] One aspect of the present invention relates to an electronic component including the above-mentioned electromagnetic shielding material. Examples of the above-mentioned electronic component include various electronic components such as electronic components included in electronic devices such as mobile phones, personal digital assistants, and medical devices, semiconductor elements, capacitors, coils, and cables. The above-mentioned electromagnetic shielding material can be bent into any shape according to the shape of the electronic component and placed inside the electronic component, or it can be placed as a cover material that covers the outside of the electronic component. Alternatively, it can be processed into a cylindrical shape and placed as a cover material that covers the outside of a cable.

[0090] [Electronic equipment] One aspect of the present invention relates to an electronic device including the above-mentioned electromagnetic shielding material. Examples of such electronic devices include mobile phones, personal digital assistants, medical devices, and other electronic devices; electronic devices including various electronic components such as semiconductor elements, capacitors, coils, and cables; and electronic devices in which electronic components are mounted on a circuit board. Such electronic devices may include the above-mentioned electromagnetic shielding material as a component of the electronic components contained in the device. Furthermore, as a component of the electronic device, the above-mentioned electromagnetic shielding material can be placed inside the electronic device, or placed as a cover material that covers the outside of the electronic device. Alternatively, it can be processed into a cylindrical shape and placed as a cover material that covers the outside of a cable.

[0091] One example of how the above-mentioned electromagnetic shielding material can be used is to cover a semiconductor package on a printed circuit board with the shielding material. For example, "Electromagnetic Shielding Technology for Semiconductor Packages" (Toshiba Review Vol. 67 No. 2 (2012) P. 8) discloses a method for obtaining a high shielding effect by performing ground wiring by electrically connecting the side vias at the edge of the package substrate to the inner surface of the shielding material when covering a semiconductor package with the shielding material. In order to perform such wiring, it is desirable that the outermost layer on the electronic component side of the shielding material be a metal layer. The above-mentioned electromagnetic shielding material includes one or more multilayer structures having the above-mentioned high permeability layer between two metal layers, and one or both of the outermost layers of the shielding material can be metal layers, so it can be suitably used when performing the above-mentioned wiring. [Examples]

[0092] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the embodiments shown in the examples.

[0093] [Example 1] <Preparation of coating solution> In a plastic bottle, Fe-Si-Al flattened magnetic particles (Sendust MFS-SUH, manufactured by MKT Corporation) 100g Polystyrene polybutadiene block copolymer (manufactured by Sigma-Aldrich Japan) 12g Cyclohexanone 205g The mixture was added and mixed in a vibrating stirrer for 1 hour to prepare the coating solution.

[0094] <Fabrication of magnetic particle-containing layer (high permeability layer)> (Film formation of a magnetic particle-containing layer) A coating solution was applied to the release surface of a release-treated PET film (PET75TR manufactured by Nippa Co., Ltd., also referred to as "release film" below) using a blade coater with a coating gap of 300 μm, and dried in a drying apparatus at an internal ambient temperature of 80°C for 30 minutes to form a film-like magnetic particle-containing layer.

[0095] (Pressurization treatment of magnetic particle-containing layer) The upper and lower press plates of a plate press machine (large hot press TA-200-1W manufactured by Yamamoto Iron Works Co., Ltd.) are heated to 140°C (internal temperature of the press plates), and the magnetic particle-containing layer on the release film is placed in the center of the press plate along with the release film, and a pressure of 4.66 N / mm is applied. 2 The pressure was applied and held for 10 minutes. After the upper and lower press plates were cooled to 50°C (internal temperature of the press plates) while maintaining the pressure, the magnetic particle-containing layer was removed along with the release film.

[0096] <Formation of shielding material> A portion of the magnetic particle-containing layer after the release film was peeled off was cut out and used as a sample for the permeability measurement, electrical conductivity measurement, and fracture resistance evaluation described below. After cutting out the sample, a 5 μm thick double-sided tape (NeoFix5 S2 manufactured by Nichiei Shinka Co., Ltd.) was attached to the top and bottom surfaces of the magnetic particle-containing layer, and then a 10 μm thick copper foil (compliant with JIS H3100:2018 standard, alloy number C1100R, copper content 99.90% by mass or more) was attached to the top and bottom surfaces. Thus, the electromagnetic wave shielding material of Example 1 was obtained. The shielding material of Example 1 includes a multilayer structure of "copper foil / magnetic particle-containing layer (high permeability layer) / copper foil".

[0097] <Measurement of magnetic permeability> The above magnetic particle-containing layer was cut into a rectangle measuring 28 mm x 10 mm, and the permeability was measured using a permeability measuring device (per01 manufactured by Keycom Co., Ltd.). The permeability was determined as the real part (μ') of the complex ratio permeability at a frequency of 100 kHz.

[0098] <Measurement of electrical conductivity> A 30mm diameter cylindrical main electrode was connected to the negative terminal of a digital super-insulation resistance meter (TR-811A, manufactured by Takeda Riken), and a 40mm inner diameter, 50mm outer diameter ring electrode was connected to the positive terminal. The main electrode and the ring electrode were placed on a 60mm x 60mm sample piece of magnetic particle-containing layer, and a voltage of 25V was applied to both electrodes to measure the surface electrical resistivity of the magnetic particle-containing layer alone. The electrical conductivity of the magnetic particle-containing layer was calculated from the surface electrical resistivity and the following formula. The thickness of the magnetic particle-containing layer was determined by the method described below. Electrical conductivity [S / m] = 1 / (Surface electrical resistivity [Ω] × Thickness [m])

[0099] <Acquisition of cross-sectional image of shield material> The following method was used to perform cross-sectional processing to expose the cross-section of the shielding material. The shielding material, cut to a size of 3mm x 3mm, was embedded in resin, and the cross-section of the shielding material was cut using an ion milling device (Hitachi High-Tech Corporation IM4000PLUS). The cross-section of the exposed shielding material was observed using a scanning electron microscope (Hitachi High-Tech SU8220) under conditions of an acceleration voltage of 2kV and a magnification of 100x to obtain a backscattered electron image. From the obtained image, the thickness of the magnetic particle-containing layer, the two metal layers, and the entire shielding material was measured at five points using the scale bar as a reference. The arithmetic mean of these measurements was taken as the thickness of the magnetic particle-containing layer, the thickness of each of the two metal layers, and the total thickness of the shielding material.

[0100] <Acquisition of cross-sectional images of magnetic particle-containing layers (high permeability layers)> Similarly to the above, the cross-section of the shielding material was processed and exposed. The portion containing magnetic particles was observed using a scanning electron microscope (Hitachi High-Tech Corporation SU8220) under conditions of an acceleration voltage of 2kV and a magnification of 1000x, and a backscattered electron image was obtained.

[0101] <Measurement of aspect ratio of magnetic particles and degree of orientation of flattened particles> Using the backscattered electron images obtained above, the aspect ratio of the magnetic particles was determined by the method described earlier, and flattened particles were identified from the aspect ratio values. It was determined whether or not the magnetic particle-containing layer contained flattened particles as magnetic particles, as described earlier. If it was determined that flattened particles were present, "Contains flattened particles" was written in Table 1, and if it was determined that flattened particles were not present, "Not present" was written in Table 1. If it was determined that flattened particles were present, the degree of orientation of the magnetic particles identified as flattened particles was determined by the method described earlier. In addition, the average value (arithmetic mean) of the aspect ratios of all particles identified as flattened particles was taken as the aspect ratio of the flattened particles contained in the magnetic particle-containing layer.

[0102] <Magnetic particle content of magnetic particle-containing layer (high permeability layer)> The content of magnetic particles relative to the total mass of the magnetic particle-containing layer was calculated as the content of magnetic particles relative to the total amount of solids in the coating solution. Here, solids refer to the components excluding the solvent, and in the above coating solution, these are magnetic particles and polystyrene-butadiene block copolymer. The ratio of magnetic particles to the total mass of the magnetic particle-containing layer can also be determined from the total mass of the magnetic particle-containing layer and the mass of magnetic particles extracted from the magnetic particle-containing layer by a known method.

[0103] <Evaluation of fracture resistance> A sample of the magnetic particle-containing layer was bent at a right angle, and the bent portion was observed at 500x magnification using an optical microscope (Nikon LV150) to check for the occurrence of fracture.

[0104] <Evaluation of electromagnetic shielding ability (KEC method)> A KEC method evaluation apparatus, including a signal generator, amplifier, a pair of magnetic or electric field antennas, and a spectrum analyzer, was used. Shielding material cut to 150mm x 150mm was placed between the antennas, and the ratio of the received signal strength with and without the shielding material was determined for frequencies from 100kHz to 1GHz to determine the shielding capacity. This was performed for both the magnetic field antenna and the electric field antenna to determine the magnetic field wave shielding capacity and the electric field wave shielding capacity, respectively.

[0105] <Measurement of bending width> The shielding material was cut to a size of 4 cm x 2 cm. The cut sample piece was firmly folded in half by hand, then unfolded and flattened. The unfolded piece was attached to a glass slide, and the folded portion was observed at 50x magnification using an optical microscope (Nikon LV150) to acquire an image. In the acquired image, the area that was brighter or darker than the unfolded area was identified as the deformed area, and its width was measured. This measured width was defined as the bending width.

[0106] [Example 2] When preparing the coating solution, polystyrene polybutadiene block copolymer is used. 38g of polyurethane resin (UR-8300, manufactured by Toyobo Co., Ltd.) with a solid content concentration of 30% by mass. Polyfunctional isocyanate (Coronate L, manufactured by Tosoh Corporation) 0.5g Except for the substitutions made, the electromagnetic shielding material was fabricated using the same method as in Example 1, and various measurements and evaluations shown in Tables 1 and 2 were performed.

[0107] [Example 3] The electromagnetic shielding material was prepared using the same method as in Example 1, except that 300 g of cyclohexanone was used as the coating solution and the coating gap was 500 μm. Various measurements and evaluations shown in Tables 1 and 2 were then performed.

[0108] [Example 4] The electromagnetic shielding material was prepared using the same method as in Example 1, except that 400 g of cyclohexanone was used as the coating solution and the coating gap was 600 μm. Various measurements and evaluations shown in Tables 1 and 2 were then performed.

[0109] [Example 5] The electromagnetic shielding material was prepared using the same method as in Example 1, except that the coating solution was prepared by the following method. Various measurements and evaluations shown in Tables 1 and 2 were then performed. In a plastic bottle, Iron-based nanocrystalline alloy magnetic particles (Epson Atomics KUAMETNC1 053C03A) 75g Iron-based amorphous magnetic particles (Epson Atomics AW2-08 PF-3F) 25g Polystyrene-polybutadiene block copolymer (manufactured by Sigma-Aldrich Japan) 3.2g Cyclohexanone 205g The mixture was added and mixed in a vibrating stirrer for 1 hour to prepare the coating solution.

[0110] [Example 6] When preparing the coating solution, polystyrene polybutadiene block copolymer is used. Polybenzyl methacrylate (manufactured by Sigma-Aldrich Japan) 12g Except for the substitutions made, the electromagnetic shielding material was fabricated using the same method as in Example 1, and various measurements and evaluations shown in Tables 1 and 2 were performed.

[0111] [Example 7] When preparing the coating solution, polystyrene polybutadiene block copolymer is used. Polymethyl methacrylate (manufactured by Sigma-Aldrich Japan) 12g Except for the substitutions made, the electromagnetic shielding material was fabricated using the same method as in Example 1, and various measurements and evaluations shown in Tables 1 and 2 were performed.

[0112] [Example 8] A magnetic particle-containing layer was prepared using the same method as in Example 1. Using the same copper foil as the metal layer used in Example 1, five layers of "copper foil / magnetic particle-containing layer / copper foil / magnetic particle-containing layer / copper foil" were bonded together, with the same double-sided tape used in Example 1 placed between each layer. The electromagnetic wave shielding material of Example 8 thus prepared was measured and evaluated in the same manner as in Example 1, as shown in Tables 1 and 2.

[0113] [Example 9] The electromagnetic shielding material was fabricated using the same method as in Example 8, except that the magnetic particle-containing layer was peeled off the release film after pressure treatment, stacked in three layers, and pressure-treated again in the same manner to increase the thickness of the magnetic particle-containing layer. Various measurements and evaluations shown in Tables 1 and 2 were then performed.

[0114] [Example 10] The electromagnetic shielding material was fabricated using the same method as in Example 1, except that the thickness of one of the two copper foils was changed to 20 μm. Various measurements and evaluations shown in Tables 1 and 2 were then performed.

[0115] [Example 11] The electromagnetic shielding material was fabricated using the same method as in Example 1, except that the thickness of one of the two copper foils was changed to 18 μm and the thickness of the other to 2 μm. Various measurements and evaluations shown in Tables 1 and 2 were then performed.

[0116] [Example 12] The electromagnetic shielding material was prepared using the same method as in Example 1, except that the two copper foils were each replaced with 15 μm thick aluminum foils (compliant with JIS H4160:2006 standard, alloy number 1N30, quality (1)O, Al content 99.3% by mass or more). Various measurements and evaluations shown in Tables 1 and 2 were then performed.

[0117] The mass of the shielding material in Example 12, measured at a size of 15 cm x 15 cm, was 4.5 g. In contrast, the mass of the shielding material in Example 1, measured at the same size, was 6.7 g.

[0118] [Example 13] <Formation of the adhesive layer> (Preparation of Coating Liquid) Into a plastic bottle, 100 g of a polyurethane resin (UR-8300 manufactured by Toyobo Co., Ltd.) with a solid content concentration of 30% by mass 900 g of methyl ethyl ketone were added and mixed with a shaking stirrer for 1 hour to prepare a coating liquid.

[0119] (Formation of Adhesive Layer) The coating liquid was applied to the release surface of a release-treated PET film (PET75TR manufactured by Nippa Co., Ltd.) with a blade coater having a coating gap of 300 μm, and dried in a drying apparatus at an internal atmosphere temperature of 80°C for 30 minutes, and an adhesive layer corresponding to the above-described adhesive layer was formed in a film shape on the release film. Two adhesive layers with release films were produced by the above method.

[0120] (Formation of Magnetic Particle-Containing Layer with Adhesive Layer (High Permeability Layer)) The upper and lower press plates of a plate press (Large Hot Press TA-200-1W manufactured by Yamamoto Iron Works Co., Ltd.) were heated to 140°C (internal temperature of the press plate), and the adhesive layer with the release film was placed in the center of the press plate with the adhesive layer facing upward. A magnetic particle-containing layer produced by the method described in Example 2 was placed on the adhesive layer, and further, an adhesive layer with the release film was placed with the adhesive layer facing downward so that the adhesive layer was on the side of the magnetic particle-containing layer. It was held for 10 minutes under a pressure of 4.66 N / mm 2 While maintaining the pressure, the upper and lower press plates were cooled to 50°C (internal temperature of the press plate), and then the magnetic particle-containing layer with double-sided adhesive layers was taken out together with the release film.

[0121] (Formation of Shielding Material) The upper and lower press plates of a plate press (Large Hot Press TA-200-1W manufactured by Yamamoto Iron Works Co., Ltd.) were heated to 140°C (internal temperature of the press plate), and a copper foil with a thickness of 10 μm (conforming to JIS H3100:2018 standard, alloy number C1100R, copper content 99.90% by mass or more), a magnetic particle-containing layer with double-sided adhesive layers with the release films peeled off from both sides, and a copper foil with a thickness of 10 μm were placed in the center of the press plate in this order, and 4.66 N / mm 2The pressure was applied and held for 10 minutes. After the upper and lower press plates were cooled to 50°C (internal temperature of the press plates) while maintaining the pressure, the shielding material was removed along with the release film. Subsequently, the release film was peeled off to obtain the electromagnetic shielding material of Example 13. The shielding material of Example 13 includes a multilayer structure of "copper foil / magnetic particle-containing layer (high permeability layer) / copper foil". Various measurements and evaluations were performed on the electromagnetic shielding material of Example 13 as shown in Tables 1 and 2.

[0122] [Example 14] <Formation of the adhesive layer> (Preparation of the coating solution) In a plastic bottle, 100g of polyurethane resin (Toyobo UR-8300) with a solid content concentration of 30% by mass. Methyl ethyl ketone 900g The mixture was added and mixed in a vibrating stirrer for 1 hour to prepare the coating solution.

[0123] (Formation of adhesive layer) A coating solution was applied to a 10 μm thick copper foil (compliant with JIS H3100:2018 standard, alloy number C1100R, copper content of 99.90% by mass or more) using a blade coater with a coating gap of 100 μm. The solution was then dried for 30 minutes in a drying apparatus with an internal ambient temperature of 80°C to form an adhesive layer corresponding to the adhesive layer described above, in film form on the metal layer. Two metal layers with adhesive layers were fabricated using the method described above.

[0124] <Formation of shielding material> The upper and lower press plates of a plate press machine (large hot press TA-200-1W manufactured by Yamamoto Iron Works Co., Ltd.) are heated to 140°C (internal temperature of the press plates). An adhesive-coated metal layer is placed in the center of the press plate with the adhesive layer facing upwards. A magnetic particle-containing layer, prepared by the method described in Example 2, is placed on top of the adhesive layer. Furthermore, an adhesive-coated layer is placed on top of that, with the adhesive layer facing downwards so that the adhesive layer faces the magnetic particle-containing layer, and the pressure is 4.66 N / mm. 2The pressure was applied and maintained for 10 minutes. After the upper and lower press plates were cooled to 50°C (internal temperature of the press plates) while the pressure was maintained, the shielding material was removed. Subsequently, the release film was peeled off to obtain the electromagnetic shielding material of Example 14. The shielding material of Example 14 includes a multilayer structure of "copper foil / magnetic particle-containing layer (high permeability layer) / copper foil". Various measurements and evaluations were performed on the electromagnetic shielding material of Example 14 as shown in Tables 1 and 2.

[0125] [Example 15] Except for using 38 g of polystyrene-polybutadiene block copolymer and 250 g of cyclohexanone in the coating solution, the electromagnetic shielding material was prepared using the same method as in Example 1, and various measurements and evaluations shown in Tables 1 and 2 were performed.

[0126] [Example 16] The electromagnetic shielding material was prepared using the same method as in Example 1, except that the amount of polystyrene-polybutadiene block copolymer in the coating solution was 45 g and the amount of cyclohexanone was 260 g. Various measurements and evaluations shown in Tables 1 and 2 were then performed.

[0127] [Comparative Example 1] The electromagnetic shielding material was prepared using the same method as in Example 1, except that the coating solution was prepared by the following method. Various measurements and evaluations shown in Tables 1 and 2 were then performed. In a plastic bottle, Iron-based amorphous magnetic particles (Epson Atomics AW2-08 PF-15F) 100g Polystyrene-polybutadiene block copolymer (manufactured by Sigma-Aldrich Japan) 3.2g Cyclohexanone 205g The mixture was added and mixed in a vibrating stirrer for 1 hour to prepare the coating solution.

[0128] [Comparative Example 2] The electromagnetic shielding material was prepared using the same method as in Example 1, except that 500 g of cyclohexanone was used as the coating solution and the coating gap was 800 μm. Various measurements and evaluations shown in Tables 1 and 2 were then performed.

[0129] [Comparative Example 3] An electromagnetic shielding material was fabricated using the same method as in Example 1, except that a metal layer (copper foil) was placed on only one side of the magnetic particle-containing layer. Various measurements and evaluations shown in Tables 1 and 2 were then performed.

[0130] [Comparative Example 4] The electromagnetic shielding material was prepared using the same method as in Example 1, except that the coating solution was prepared by the following method. Various measurements and evaluations shown in Tables 1 and 2 were then performed. The layer formed using the following coating solution is a resin layer that does not contain magnetic particles. In a plastic bottle, Polystyrene polybutadiene block copolymer (manufactured by Sigma-Aldrich Japan) 20g Cyclohexanone 205g The mixture was added and mixed in a vibrating stirrer for 1 hour to prepare the coating solution.

[0131] [Comparative Example 5] Copper foil (10 μm thick) alone was used as the electromagnetic shielding material in Comparative Example 5, and various measurements and evaluations shown in Tables 1 and 2 were performed using the same method as in Example 1.

[0132] [Comparative Example 6] Copper foil (20 μm thick) alone was used as the electromagnetic shielding material in Comparative Example 6, and various measurements and evaluations shown in Tables 1 and 2 were performed using the same method as in Example 1.

[0133] [Comparative Example 7] A magnetic particle-containing layer was prepared using the same method as in Example 1. Using the same copper foil as the metal layer used in Example 1, three layers consisting of a "magnetic particle-containing layer / copper foil / magnetic particle-containing layer" were bonded together, with the same double-sided tape used in Example 1 placed between each layer. The electromagnetic shielding material of Comparative Example 7 thus prepared was measured and evaluated in the same manner as in Example 1, as shown in Tables 1 and 2.

[0134] [Reference example 1] A copper plate (115 μm thick) alone was used as the electromagnetic shielding material in Reference Example 1, and various measurements and evaluations shown in Tables 1 and 2 were performed using the same method as in Example 1.

[0135] <Measurement of the glass transition temperature (Tg) of resins> The same resin (pellet or powder sample) used to prepare the coating solution was placed in an aluminum sample pan, sealed using a press, and heat flow measurements were performed using a T.A. Instruments Q100 differential scanning calorimeter under the following conditions. From the measurement results, the glass transition temperature of the resin was determined as the baseline shift start temperature of the heat flowchart during heating. (Measurement conditions) Scanning temperature: -80.0℃ to 200.0℃ Heating rate: 10.0℃ / min

[0136] The results are shown in Table 1 (Tables 1-1 to 1-2) and Table 2 (Tables 2-1 to 2-2). In Table 1, the columns for electric field shielding ability and magnetic field shielding ability that show values ​​with "or more" indicate that the values ​​were above the evaluation upper limit of the KEC method evaluation device used. For magnetic field shielding ability, it is desirable that the magnetic field shielding ability at 100 kHz be 10.0 dB or more, and the magnetic field shielding ability at 10 MHz be 70.0 dB or more.

[0137] [Table 1-1]

[0138] [Table 1-2]

[0139] As shown in Table 1, the electromagnetic shielding materials of Examples 1 to 16, which include a multilayer structure with a high-permeability layer between two metal layers, having a complex relative permeability real part of 30 or more at a frequency of 100 kHz, exhibit excellent electric field shielding and magnetic field shielding capabilities across a wide frequency range from low to high frequencies. In contrast, the electromagnetic shielding materials of Comparative Examples 1 to 7 showed lower shielding capabilities against magnetic fields at 100 kHz and / or 10 MHz in the low-frequency range compared to the electromagnetic shielding materials of Examples 1 to 16. Reference Example 1 is a reference example showing that, with a metal layer alone, in order to obtain high electric field shielding and high magnetic field shielding capabilities across a wide frequency range from low to high frequencies, the metal layer must be significantly thicker than the metal layer included in the electromagnetic shielding materials of the Examples. However, as shown in Table 2, it was confirmed that such a thick metal layer results in a wider bending width.

[0140] [Table 2-1]

[0141] [Table 2-2] [Industrial applicability]

[0142] One aspect of the present invention is useful in the technical fields of various electronic components and various electronic devices.

Claims

1. The multilayer structure includes a high-permeability layer between two metal layers, which is an insulating layer with a real portion of the complex relative permeability of 40 or more at a frequency of 100 kHz, and The aforementioned high-permeability layer is an electromagnetic wave shielding material containing Sendust particles.

2. The electromagnetic wave shielding material according to claim 1, wherein the high permeability layer includes flattened particles as the Sendust particles.

3. The electromagnetic wave shielding material according to claim 2, wherein the degree of orientation, which is the sum of the absolute value of the average value of the orientation angle of the flattened particles with respect to the surface of the high permeability layer and the variance of the orientation angle, is 30° or less.

4. The electromagnetic wave shielding material according to any one of claims 1 to 3, wherein the high permeability layer includes a resin.

5. The electromagnetic wave shielding material according to claim 4, wherein the glass transition temperature Tg of the resin is 50°C or less.

6. Let T1 be the thickness of one of the two metal layers, and T2 be the thickness of the other metal layer. T1 is greater than or equal to T2, and An electromagnetic wave shielding material according to any one of claims 1 to 5, wherein the thickness ratio, T2 / T1, is 0.15 or more.

7. The electromagnetic wave shielding material according to any one of claims 1 to 6, wherein one or both of the two metal layers are metal layers with a metal content of 80.0% by mass or more, selected from the group consisting of Al and Mg.

8. The electromagnetic wave shielding material according to any one of claims 1 to 7, further comprising one or more layers selected from the group consisting of adhesive layers and bonding layers.

9. The electromagnetic wave shielding material according to any one of claims 1 to 8, wherein the total thickness of the metal layers contained in the electromagnetic wave shielding material is 100 μm or less.

10. The electromagnetic wave shielding material according to any one of claims 1 to 9, wherein the total thickness of the electromagnetic wave shielding material is 200 μm or less.

11. The electromagnetic wave shielding material according to any one of claims 1 to 10, wherein the complex ratio permeability real portion of the high permeability layer at a frequency of 100 kHz is 40 or more and 200 or less.

12. An electronic component comprising an electromagnetic shielding material according to any one of claims 1 to 11.

13. An electronic device comprising an electromagnetic shielding material according to any one of claims 1 to 11.

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