Electromagnetic shielding materials, electronic components, and electronic equipment

Abstract

An electromagnetic shielding member is provided that has at least one magnetic layer containing magnetic particles and a resin, wherein the peak top temperature of the loss tangent Tanδ in dynamic viscoelasticity measurement at 1 Hz is greater than or equal to 0° and less than 60°C. An electronic component and an electronic device containing this electromagnetic shielding member are also provided.

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a soft magnetic film to be mounted on a circuit board of an electronic device. Specifically, paragraph 0095 of Patent Document 1 describes that a soft magnetic film can be laminated onto an antenna, a coil, or a circuit board on which these are formed on the surface. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] WO2014 / 132880 [Overview of the project] [Problems that the invention aims to solve]

[0004] 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. Electromagnetic shielding materials (hereinafter also referred to as "shielding materials") can exhibit shielding performance (shielding ability) by reflecting electromagnetic waves incident on the shielding material and / or attenuating them within the shielding material. For example, a soft magnetic film as described in Patent Document 1 can function as an electromagnetic shielding material.

[0005] The following two performance characteristics are desirable for electromagnetic shielding materials. Firstly, it is desirable to be able to exhibit high shielding capabilities against electromagnetic waves. Electromagnetic shielding materials that exhibit high shielding capabilities against electromagnetic waves are desirable because they can significantly reduce the effects of electromagnetic waves on electronic components and electronic equipment. Secondly, it has excellent moldability. Electromagnetic shielding materials can be processed into various shapes for incorporation into electronic components or electronic devices. Excellent moldability means that defects such as shape defects and breakage are less likely to occur during molding. Electromagnetic shielding materials with excellent moldability are desirable, for example, because they are less likely to break in molded products during three-dimensional molding (in other words, three-dimensional molding). However, Patent Document 1 does not mention anything about the above-mentioned moldability.

[0006] In view of the above, one aspect of the present invention aims to provide an electromagnetic wave shielding material that can exhibit high shielding performance against electromagnetic waves and has excellent moldability. [Means for solving the problem]

[0007] One aspect of the present invention is as follows: [1] Having one or more magnetic layers containing magnetic particles and resin, An electromagnetic shielding material in which the peak-top temperature of the loss tangent Tanδ in a 1 Hz dynamic viscoelasticity measurement (hereinafter also referred to as "Tanδ peak-top temperature") is between 0°C and 60°C. [2] The electromagnetic wave shielding material according to [1], further comprising one or more adhesive layers. [3] The electromagnetic wave shielding material according to [2], further comprising a resin layer located between two adhesive layers. [4] Further having two or more metal layers, An electromagnetic wave shielding material according to any one of [1] to [3], comprising one or more magnetic layers sandwiched between two metal layers. [5] An electromagnetic shielding material according to any of [1] to [4], wherein the storage modulus E' in a dynamic viscoelastic measurement at 1 Hz is 0.010 GPa or more and less than 10.000 GPa at 60°C (hereinafter, the above storage modulus E' will also be referred to as "E' at 60°C"). [6] The electromagnetic shielding material according to any one of [1] to [5], comprising a resin having a urethane structure in the magnetic layer. [7] The peak top temperature of the loss tangent Tanδ in the dynamic viscoelasticity measurement at 1 Hz is 15°C or higher and less than 40°C, and An electromagnetic shielding material according to any one of [1] to [6], wherein the storage modulus E' in a dynamic viscoelastic measurement at 1 Hz is 0.010 GPa or more and less than 10.000 GPa at 60°C. [8] The electromagnetic wave shielding material according to any one of [1] to [7], wherein the magnetic layer comprises flattened metal particles as the magnetic particles. [9] An electromagnetic shielding material in sheet form, as described in any of [1] to [8]. Electronic components containing electromagnetic shielding material as described in any of

[10] [1] to [9]. Electronic equipment containing an electromagnetic shielding material as described in any of

[11] [1] to [9]. [Effects of the Invention]

[0008] According to one aspect of the present invention, an electromagnetic wave shielding material can be provided that exhibits high shielding performance against electromagnetic waves and has excellent moldability. Furthermore, according to one aspect of the present invention, an electronic component and electronic device containing this electromagnetic wave shielding material can be provided. [Modes for carrying out the invention]

[0009] [Electromagnetic shielding material] One aspect of the present invention relates to an electromagnetic wave shielding material having one or more magnetic layers containing magnetic particles and resin, wherein the peak top temperature of the loss tangent Tanδ in a dynamic viscoelasticity measurement at 1 Hz is 0°C or higher and less than 60°C.

[0010] In the present invention and this specification, "electromagnetic wave shielding material" means a material that can exhibit shielding ability against electromagnetic waves of at least one frequency or at least a portion of a frequency band. "Electromagnetic waves" include magnetic field waves and electric field waves. Preferably, the "electromagnetic wave shielding material" is a material that can exhibit shielding ability against magnetic field waves of at least one frequency or at least a portion of a frequency band, and against one or both of electric field waves of at least one frequency or at least a portion of a frequency band.

[0011] In the present invention and this specification, "magnetic" means ferromagnetic property. Details of the magnetic layer will be described later.

[0012] <Peak top temperature of Tanδ> The peak top temperature of the loss tangent Tanδ in the dynamic viscoelasticity measurement at 1 Hz of the electromagnetic wave shielding material is 0°C or higher and lower than 60°C. "Tan" is an abbreviation of Tangent. In the present invention and this specification, the peak top temperature of the loss tangent Tanδ (tangent delta) is obtained by the dynamic viscoelasticity measurement described below. The dynamic viscoelasticity measurement is performed using a dynamic viscoelasticity measuring device. As the dynamic viscoelasticity measuring device, for example, the dynamic viscoelasticity measuring device DMS6100 manufactured by Hitachi High-Tech Science Corporation can be used, and this device was used in the examples described later. The measurement procedure is as follows. A measurement sample with a length of 28 mm and a width of 10 mm is cut out from the electromagnetic wave shielding material to be measured. In the dynamic viscoelasticity measuring device, the viscoelasticity of the above measurement sample is measured under the following measurement conditions. The maximum point of the loss tangent Tanδ in the temperature range from -50°C to 100°C measured in this way is taken as the peak top of the loss tangent Tanδ. When there are two or more of the above maximum points in the data of the above temperature range, the maximum point on the highest temperature side is taken as the peak top of the loss tangent Tanδ. The temperature of the peak top thus specified is taken as the peak top temperature of the loss tangent Tanδ. On the other hand, when there is no maximum point of the loss tangent Tanδ in the data of the above temperature range, it is determined that there is no peak top of Tanδ. (Measurement conditions) Distance between chucks: 10 mm Measurement temperature range: from -50°C to 100°C Temperature rising rate: 2°C / min Sampling rate: 3 seconds Measurement frequency: 1 Hz

[0013] The peak top temperature of Tanδ of the electromagnetic wave shielding material is 0°C or higher and lower than 60°C. The present inventors speculate that this contributes to the electromagnetic wave shielding material being able to exhibit excellent formability. Regarding formability, forming that is performed without heating the forming target and / or the mold, or that is performed by heating with little increase in temperature, is generally called cold forming. The electromagnetic wave shielding material having a peak top temperature of Tanδ of 0°C or higher and lower than 60°C is preferable from the viewpoint of suppressing breakage of a molded product obtained by three-dimensional forming by forming generally called cold forming. The present inventors speculate that this is because the peak top temperature of Tanδ being within the above range can contribute to the electromagnetic wave shielding material exhibiting elongation suitable for cold forming. However, the present invention is not limited to the speculation described in this specification. From the viewpoint of further improving formability, the peak top temperature of Tanδ of the electromagnetic wave shielding material is preferably 58°C or lower, more preferably 55°C or lower, and still more preferably 53°C or lower, 50°C or lower, 48°C or lower, 45°C or lower, 43°C or lower, 41°C or lower, 40°C or lower, lower than 40°C, 38°C or lower, 35°C or lower, 33°C or lower, 30°C or lower in that order. On the other hand, the peak top temperature of Tanδ of the electromagnetic wave shielding material is 0°C or higher, and can also be, for example, 1°C or higher, 3°C or higher, 5°C or higher, 10°C or higher, 12°C or higher, 15°C or higher, 17°C or higher, or 20°C or higher.

[0014] The peak top temperature of Tanδ can be controlled by the type of layer constituting the electromagnetic wave shielding material, the type and content rate of the resin contained in the magnetic layer, etc. Details regarding this point will be described later.

[0015] Hereinafter, the electromagnetic wave shielding material will be described in more detail.

[0016] <Magnetic layer> The electromagnetic wave shielding material has one or more magnetic layers containing magnetic particles and a resin. In one form, the electromagnetic wave shielding material can be composed of only one magnetic layer or only two or more magnetic layers, and in another form, it can include one or more of various layers described later.

[0017] (magnetic particles) 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 strong magnetic fields and exhibit shielding ability. Therefore, it is preferable that the magnetic particles contained in the magnetic layer are metal particles. In the present invention and this specification, a layer containing metal particles as magnetic particles corresponds to a "magnetic layer".

[0018] metal particles Examples of metal particles used as magnetic 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. In addition to the constituent elements of the metal (including alloys), the metal particles may contain elements contained in additives that can be optionally added and / or elements contained in impurities that may be unintentionally introduced during the manufacturing process of the metal particles, in any desired proportion. 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.

[0019] In one embodiment, the shielding ability of an electromagnetic wave shielding material against electromagnetic waves can be evaluated using the permeability (more specifically, the real part of the complex relative permeability) of the magnetic layer contained in the electromagnetic wave shielding material as an indicator. A magnetic layer having high permeability (more specifically, the real part of the complex relative permeability) is preferable because it can exhibit high shielding ability against electromagnetic waves.

[0020] 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 3 MHz (megahertz) 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. From the viewpoint of exhibiting even better electromagnetic shielding performance, the permeability of the magnetic layer contained in the electromagnetic shielding material (real part of the complex relative permeability at a frequency of 3 MHz) is preferably 40 or more, more preferably 100 or more, and even more preferably 120 or more. Furthermore, the above permeability can be, for example, 500 or less, 300 or less, or 200 or less, and can exceed the values ​​exemplified herein. Electromagnetic shielding materials with high permeability are preferred because they can exhibit excellent electromagnetic shielding performance.

[0021] From the viewpoint of forming a magnetic layer exhibiting high magnetic permeability, the magnetic particles are preferably flattened particles, and more preferably flattened metallic particles. By arranging the long side direction of the flattened particles to be closer to parallel with the in-plane direction of the magnetic 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 the magnetic layer to exhibit higher magnetic 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. An example of a magnetic layer exhibiting high magnetic permeability is a magnetic layer containing flattened particles of Sendust.

[0022] As mentioned earlier, from the viewpoint of forming a layer that exhibits high magnetic permeability as a magnetic 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 magnetic 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 magnetic 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.

[0023] 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 magnetic layer is exposed by a known method. A scanning electron microscope (SEM) image is obtained of a randomly selected region of this cross-section. The imaging conditions are an acceleration voltage of 2kV and a magnification of 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 circumscribing 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 magnetic layer shall be determined to be a "magnetic 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 magnetic 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". 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 aspect ratio and orientation degree. Furthermore, 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 magnetic layer being measured. This aspect ratio is 0.20 or less, preferably 0.15 or less, and more preferably 0.10 or less. In addition, the above aspect ratio can be, for example, 0.01 or more, 0.02 or more, or 0.03 or more.

[0024] The content of magnetic particles in the above magnetic layer can be, for example, 50% or more by mass, 60% or more by mass, 70% or more by mass, or 80% or more by mass, relative to the total mass of the magnetic layer, and can also be, for example, less than 100% by mass, 99% or less by mass, 98% or less by mass, or 95% or less by mass. The content of various components in the magnetic layer can be determined by known methods such as TG / DTA (Thermogravimetry / Differential Thermal Analysis) or extraction of various components using solvents. Note that "TG / DTA" is generally called thermogravimetric differential thermal analysis. If the composition of the magnetic layer forming composition used to form the magnetic layer is known, the content of various components in the magnetic layer can also be determined from this known composition.

[0025] In one embodiment, the magnetic layer described above can be an insulating layer. In the present invention and this specification, "insulating" means that the electrical conductivity is less than 1 S (siemens) / m. The electrical conductivity of a layer is calculated from the surface electrical resistivity of the layer and the thickness of the 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 inventors surmise that the above magnetic layer being an insulating layer is preferable for the above electromagnetic wave shielding material to exhibit even higher electromagnetic wave shielding performance. From this point of view, the electrical conductivity of the above magnetic layer is preferably less than 1 S / m, more preferably 0.5 S / m or less, even more preferably 0.1 S / m or less, and even more preferably 0.05 S / m or less. The electrical conductivity of the above magnetic layer is, for example, 1.0 × 10 -12 S / m or larger or 1.0×10 -10 It can be S / m or higher.

[0027] (resin) The above-mentioned magnetic layer is a layer containing magnetic particles and resin. The resin can act as a binder in the magnetic layer. In the present invention and this specification, a layer containing both magnetic particles and resin is referred to as a "magnetic layer". The resin content of the magnetic layer can be, for example, 5% by mass or more with respect to the total mass of the magnetic layer, and from the viewpoint of further improving moldability, it is preferably 10% by mass or more, and more preferably 15% by mass or more. Furthermore, the resin content of the magnetic layer can be, for example, 50% by mass or less with respect to the total mass of the magnetic layer, and from the viewpoint of increasing the magnetic permeability of the magnetic layer, it is preferably 45% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less.

[0028] In the present invention and this specification, "resin" means polymer, and includes rubber and elastomer. Polymers include homopolymers and copolymers. Rubber includes natural rubber and synthetic rubber. Elastomers are polymers that exhibit elastic deformation. Examples of resins included in the magnetic layer 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, polyester urethane resins, cellulose resins, ABS (acrylonitrile-butadiene-styrene) resins, nitrile-butadiene rubbers, styrene-butadiene rubbers, epoxy resins, phenolic resins, amide resins, silicone resins, styrene elastomers, olefin elastomers, vinyl chloride elastomers, polyester elastomers, polyamide elastomers, polyurethane elastomers, and acrylic elastomers. In particular, from the viewpoint of further improving moldability, resins having a urethane structure, such as polyurethane resin, polyester urethane resin, and polyurethane elastomer, are preferred. In the present invention and this specification, "resin having a urethane structure" means a resin having a structure containing one or more urethane bonds (-NH-C(=O)O-). The type of resin contained in the magnetic layer can be determined by organic analysis such as pyrolysis GC / MS (Gas Chromatography / Mass Spectrometry) or Fourier transform infrared spectroscopy. For example, if isocyanate component residue and / or polyol component residue are observed by pyrolysis GC / MS, it can be determined that the resin has a urethane structure.

[0029] The glass transition temperature Tg of the resin contained in the magnetic layer is preferably 50°C or less, more preferably 40°C or less, and even more preferably 30°C or less, 20°C or less, 10°C or less, 0°C or less, and -10°C or less, in that order. Having the glass transition temperature Tg of the resin contained in the magnetic layer within the above range is preferable for controlling the peak top temperature of Tanδ of the electromagnetic wave shielding material to less than 60°C, and is also preferable from the viewpoint of giving the electromagnetic wave shielding material more elongation suitable for cold forming. Furthermore, the glass transition temperature Tg of the resin contained in the magnetic layer can be, for example, -50°C or higher, -40°C or higher, or -30°C or higher. In the present invention and this specification, the glass transition temperature Tg of the resin is a value obtained from the measurement results of heat flow measurement using a differential scanning calorimeter as the baseline shift start temperature of the heat flowchart during heating.

[0030] In addition to the above components, the magnetic layer may also contain one or more known additives such as curing agents, dispersants, stabilizers, and coupling agents in any amount.

[0031] For example, a compound having a crosslinking group can be used as a curing agent. In the present invention and this specification, "crosslinking group" means a group that can undergo a crosslinking reaction, and a specific example thereof is an isocyanate group. Furthermore, a compound having two or more crosslinking groups (for example, two to four) in one molecule is preferred as the curing agent, and a specific example thereof is polyisocyanate. Polyisocyanate is a compound having two or more isocyanate groups in one molecule. In one embodiment, with 100 parts by mass of resin contained in the magnetic layer, the magnetic layer preferably contains 1 part by mass or more of curing agent, and more preferably 2.5 parts by mass or more of curing agent. In another embodiment, with 100 parts by mass of resin contained in the magnetic layer, the magnetic layer may contain 100 parts by mass or less, or 40 parts by mass or less, of curing agent. When the curing agent is a compound having a crosslinking group, in a magnetic layer containing such curing agent, the curing agent may be included in a form after at least a portion of the crosslinking groups have undergone a crosslinking reaction.

[0032] The electromagnetic shielding material described above includes at least one magnetic layer, and more specifically, may include only one magnetic layer, or may include two or more magnetic layers that are the same or different in composition and / or thickness. When the above electromagnetic wave shielding material includes only one magnetic layer, the thickness of this single magnetic layer can be, for example, 5 μm or more, and from the viewpoint of further improving the shielding ability against electromagnetic waves, it is preferable that it be 10 μm or more, and more preferably 20 μm or more. Furthermore, the thickness of this single magnetic layer can be, for example, 100 μm or less or 90 μm or less, and from the viewpoint of further improving moldability, it is preferable that it be less than 90 μm, more preferably 80 μm or less, and even more preferably 70 μm or less. When the above electromagnetic wave shielding material includes two or more magnetic layers, the thickness of each of these two or more magnetic layers (i.e., the thickness per layer) can be, for example, 5 μm or more, and from the viewpoint of further improving the shielding ability against electromagnetic waves, it is preferable that it be 10 μm or more, and more preferable that it be 20 μm or more. Furthermore, the thickness of this single magnetic layer can be, for example, 100 μm or less or 90 μm or less, and from the viewpoint of further improving moldability, it is preferable that it be less than 90 μm, and more preferable that it be 80 μm or less. The thicknesses of each of the two or more magnetic layers can be the same or different.

[0033] The thickness of each layer in the electromagnetic shielding material is determined by imaging a cross-section exposed by a known method using a scanning electron microscope (SEM), and then taking the arithmetic mean of the thicknesses of five randomly selected points in the resulting SEM image.

[0034] The electromagnetic shielding material described above can consist of only a single magnetic layer in one embodiment, or it can include one or more magnetic layers and one or more other layers in another embodiment. The various layers that may be included in the electromagnetic shielding material described above are explained below.

[0035] <Adhesive layer> The electromagnetic shielding material described above may include one or more adhesive layers. In the electromagnetic shielding material described above, at least one adhesive layer may be positioned as a layer in direct contact with the magnetic layer. In the present invention and this specification, "direct contact" with respect to two layers means that there is no other layer interposed between these two layers. In the present invention and this specification, "adhesive layer" means a layer that has tackiness on its surface at room temperature. Here, "room temperature" means 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. Including an adhesive layer in the electromagnetic shielding material is preferable in terms of controlling the peak top temperature of Tanδ of the electromagnetic shielding material to less than 60°C, and is also preferable from the viewpoint of giving the electromagnetic shielding material more elongation suitable for cold forming.

[0036] In one embodiment, the glass transition temperature Tg of the adhesive layer can be, for example, less than 50°C, 45°C or less, or 40°C or less, and can also be, for example, -70°C or higher. The glass transition temperature Tg of the adhesive layer is determined from the measurement results of heat flow measurement using a differential scanning calorimetry (DSC) as the midpoint temperature between the starting point and the ending point of the descent of the DSC chart.

[0037] 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 also be applied, for example, to a support. Application can be carried out using known application equipment such as a blade coater or die coater. 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 electromagnetic shielding material can also be manufactured by coating a magnetic layer with an adhesive layer by a composition for forming an adhesive layer, in which the adhesive is dissolved and / or dispersed in a solvent, and then drying the mixture.

[0038] 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.

[0039] The above electromagnetic shielding material may have one or more adhesive layers, more specifically, it may have only one adhesive layer, or it may have two or more adhesive layers that are the same or different in composition and / or thickness. The total number of adhesive layers included in the above electromagnetic shielding material may be, for example, one to four layers, or one or two layers. If the electromagnetic shielding material described above includes only one adhesive layer, the thickness of this adhesive layer can be, for example, 0.5 μm or more, preferably 1 μm or more, and more preferably 2 μm or more. Furthermore, the thickness of this adhesive layer can be, for example, 20 μm or less, or 10 μm or less. If the electromagnetic shielding material described above includes two or more adhesive layers, the thickness of each of these two or more adhesive layers (i.e., the thickness per layer) can be, for example, 0.5 μm or more, preferably 0.8 μm or more, and more preferably 1.5 μm or more. Furthermore, the thickness of one of these adhesive layers can be, for example, 10 μm or less or 5 μm or less. The thicknesses of each of the two or more adhesive layers can be the same or different.

[0040] In one embodiment, the electromagnetic shielding material may be composed of two layers: one magnetic layer and one adhesive layer. In another embodiment, the electromagnetic shielding material may be composed of three layers: a magnetic layer, an adhesive layer, and another magnetic layer, and may include these three layers in this order. In yet another embodiment, the electromagnetic shielding material may have a resin layer between two adhesive layers. For example, the electromagnetic shielding material may include a laminated structure having the magnetic layer and a resin layer between two adhesive layers. In a laminated structure having a resin layer between two adhesive layers, the resin layer may be a layer that is in direct contact with one or both of the two adhesive layers, and it is preferable that it is a layer that is in direct contact with both adhesive layers. In one embodiment, the electromagnetic shielding material may be composed of four layers: a magnetic layer, an adhesive layer, a resin layer, and another adhesive layer, and may include these four layers in this order. In yet another embodiment, the electromagnetic shielding material may have a laminated structure having a resin layer between two adhesive layers on both sides of the magnetic layer. An example of an electromagnetic shielding material with such a configuration is one composed of seven layers: an adhesive layer, a resin layer, an adhesive layer, a magnetic layer, an adhesive layer, a resin layer, and an adhesive layer, with these seven layers included in this order. In another embodiment, the above electromagnetic shielding material may further include a metal layer, as described later, in addition to the above layer configuration.

[0041] The fact that the above-mentioned electromagnetic shielding material has a resin layer between two adhesive layers is preferable from the viewpoint of providing the electromagnetic shielding material with more elongation suitable for cold forming. In the present invention and this specification, "resin layer" means a layer containing resin, and may be a layer mainly composed of resin. The main component is the component that accounts for the largest amount by mass among the components constituting the layer. The resin content of the resin layer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, based on the total mass of the resin layer. Furthermore, the resin content in the resin layer may be, for example, 100% by mass or less, less than 100%, or 99% by mass or less, based on the total mass of the resin layer. The resin layer contains one or more types of resin, and may also contain one or more known additives such as plasticizers, curing agents, dispersants, stabilizers, and coupling agents in any amount. As the resin layer, for example, commercially available resin films usable as plastic substrates, resin films manufactured by known methods, etc., can be used. Examples of resins included in the resin layer include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, cellophane, diacetylcellulose, triacetylcellulose, acetylcellulose butyrate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, polystyrene, polycarbonate, polymethylpentene, polysulfone, polyetheretherketone, polyethersulfone, polyetherimide, polyimide, fluororesin, nylon, acrylic resin, polyamide, cycloolefin, polyethersulfan, and other resins. Among these, resin films such as polyethylene terephthalate, polyethylene naphthalate, and nylon are preferred because of their high mechanical strength. One form of the resin layer is the support for the double-sided tape. The thickness of the resin layer is preferably 0.1 μm or more, and more preferably 1 μm or more. Furthermore, the thickness of the resin layer is preferably, for example, 100 μm or less, more preferably 10 μm or less, and even more preferably less than 10 μm. The electromagnetic wave shielding material may contain only one resin layer, or it may contain two or more layers (for example, two or three layers), between the two adhesive layers.

[0042] The glass transition temperature Tg of the resin layer can be, for example, 50°C or higher, 60°C or higher, or 70°C or higher, and can also be, for example, 150°C or lower, 130°C or lower, or 110°C or lower. The glass transition temperature Tg of the resin layer is determined from the measurement results of heat flow measurement using a differential scanning calorimetry (DSC) as the midpoint temperature between the starting point and the ending point of the downward descent of the DSC chart.

[0043] <Metal layer> In the present invention and this specification, "metal layer" means a layer containing a metal. The 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.

[0044] The electromagnetic shielding material described above may further include one or more metal layers. In one embodiment, the two or more metal layers may have the same composition and thickness, and in another embodiment, they may have different compositions and / or thicknesses. In an electromagnetic shielding material including two or more metal layers, one or more magnetic layers may be positioned between the two metal layers. Here, the magnetic layer sandwiched between the two metal layers may be in direct contact with one or both of the two metal layers, or it may be in indirect contact via one or more other layers (e.g., adhesive layers). The metal layers may be, for example, the outermost layers of one or both of the electromagnetic shielding materials. In one embodiment, the electromagnetic shielding material may have the metal layers, the laminated structure (i.e., a laminated structure having a resin layer between two adhesive layers), the magnetic layer, the laminated structure, and the metal layers in this order. In this embodiment, the electromagnetic shielding material can be composed of nine layers, for example, a metal layer, an adhesive layer, a resin layer, an adhesive layer, a magnetic layer, an adhesive layer, a resin layer, an adhesive layer, and a metal layer, and these nine layers can be included in this order. Furthermore, it can also have a metal layer, the above laminated structure (i.e., a laminated structure having a resin layer between two adhesive layers), a magnetic layer, the above laminated structure, a metal layer, the above laminated structure, a magnetic layer, the above laminated structure, and a metal layer, in this order. In this embodiment, the electromagnetic shielding material can be composed of seventeen layers, for example, a metal layer, an adhesive layer, a resin layer, an adhesive layer, a magnetic layer, an adhesive layer, a resin layer, an adhesive layer, a metal layer, an adhesive layer, a resin layer, an adhesive layer, a magnetic layer, an adhesive layer, a resin layer, an adhesive layer, and a metal layer, and these seventeen layers can be included in this order. A configuration in which the magnetic layer is sandwiched between two metal layers is preferable from the viewpoint of improving the shielding ability against magnetic field waves with frequencies in the range of 0.01 to 100 MHz.

[0045] 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.

[0046] 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, a sheet of pure metal or alloy can be used as the metal layer. For example, a commercially available metal foil or a metal foil manufactured by a known method can be used as the metal layer. For pure metal Cu, sheets of various thicknesses (so-called copper foil) are commercially available. 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, sheets of Al (so-called aluminum foil) of various thicknesses are commercially available. For example, such aluminum foil can be used as the metal layer.

[0047] 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 a Mg content of 80.0 mass% or more, and may also have a 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.

[0048] <60℃ E'> With respect to viscoelasticity, from the viewpoint that the electromagnetic shielding material may exhibit elongation that is more suitable for cold forming, the storage modulus E' of the electromagnetic shielding material in dynamic viscoelastic measurement at 1 Hz is preferably 0.010 GPa or higher, and more preferably 0.020 or higher, at 60°C. Furthermore, the E' of the electromagnetic shielding material at 60°C can be, for example, 11.000 GPa or lower. From the above viewpoint, the E' of the electromagnetic shielding material at 60°C is preferably less than 10.000 GPa, more preferably 9.000 GPa or lower, and even more preferably 5.000 GPa. In the present invention and this specification, the E' of the electromagnetic shielding material at 60°C is a value obtained by dynamic viscoelastic measurement with respect to Tanδ by the method described above. The E' at 60°C can be controlled by the type of layer constituting the electromagnetic shielding material, the type and content of the resin contained in the magnetic layer, etc. For example, including an adhesive layer in the electromagnetic shielding material, using a resin having a glass transition temperature within the range described above as the resin for the magnetic layer, and setting the resin content in the magnetic layer within the range described above are examples of means for controlling E' at 60°C to the above range.

[0049] <Manufacturing method for electromagnetic wave shielding material> (Method for forming a magnetic layer) The magnetic layer described above can be produced, for example, by applying a magnetic layer-forming composition and drying the resulting coating. The magnetic 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 preparing the magnetic layer-forming composition, or two or more solvents mixed in any proportion, can be used. The solvent content of the magnetic layer-forming composition is not particularly limited and should be determined considering the coatability of the magnetic layer-forming composition.

[0050] A composition for forming a magnetic layer 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.

[0051] The magnetic layer-forming composition can be applied, for example, to a support. The application can be carried out using known coating 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.

[0052] Examples of supports to which the magnetic layer-forming composition is applied include films of various resins such as polyesters (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN)), polycarbonate (PC), acrylics (e.g., polymethyl methacrylate (PMMA)), cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. For these resin films, please 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 to which the magnetic layer-forming composition is applied (the surface to be coated) can be used. One form of the release treatment is the formation of a release layer. For the release layer, please 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 release treatment on the surface to be coated, the magnetic layer and the support can be easily separated after film formation.

[0053] In one embodiment, the magnetic layer forming composition can be directly applied to the adhesive layer or to the adhesive layer of the laminated structure, using the adhesive layer as a support, the adhesive tape having the adhesive layer as a support, or the laminated structure having a resin layer between two layers as a support.

[0054] The coated layer formed by applying the magnetic 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 magnetic 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.

[0055] Regarding a composition for forming a magnetic layer, which includes magnetic particles and a resin in addition to a curing agent, the curing agent can be described in the preceding text. The magnetic layer formed using such a composition can be cured with a curing agent at any stage. Depending on the type of curing agent, the curing treatment can be heat treatment or light irradiation treatment. For example, if the curing treatment is heat treatment, in one embodiment it can be performed before the pressurization treatment described later, and in another embodiment it can be performed after the pressurization treatment described later. According to the inventors' studies, when the heat treatment is performed after the pressurization treatment, there is a tendency for the permeability of the formed magnetic layer to increase. The heat treatment can be performed, for example, by holding the magnetic layer before or after the pressurization treatment in an environment with an ambient temperature of 35°C or higher (for example, 35°C to 150°C). The holding time can be, for example, 3 to 72 hours.

[0056] 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 magnetic 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, applying pressure, as 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.

[0057] (Pressurization treatment of the magnetic layer) The magnetic layer can also be subjected to pressure treatment after film formation. By applying pressure to a magnetic layer containing magnetic particles, the density of magnetic particles within the magnetic layer can be increased, resulting in higher magnetic permeability. Furthermore, in magnetic layers containing flattened particles, the degree of orientation can be reduced by pressure treatment, resulting in higher magnetic permeability.

[0058] Pressurization can be performed by applying pressure in the thickness direction of the magnetic 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.

[0059] 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 5 seconds to 4 hours. 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 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 perform a heating and pressurizing treatment by applying heat to, for example, one or both upper and lower press plates of a plate press machine, or one of the upper and lower rolls of a roll press machine. In the heating and pressurizing treatment, the magnetic layer can be softened by heating, thereby obtaining 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. In one embodiment, a heat treatment can be performed as a curing treatment for the hardener before or after the heating and pressurizing treatment. Such a heat treatment is as described above. After heating and pressurizing in a plate press, the magnetic layer can be extracted by separating the press plates while they are still hot, for example. Alternatively, the press plates can be cooled by methods such as water cooling or air cooling while maintaining the pressure, and then the magnetic layer can be extracted by separating the press plates. In a roll press machine, the magnetic 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 magnetic layer is formed on a release film, for example, it can be subjected to pressure treatment while laminated on the release film. Alternatively, the magnetic layer can be peeled off the release film and subjected to pressure treatment as a single layer.

[0060] (Layering of various layers) As described above, the adhesive layer can be bonded to the magnetic layer as an adhesive tape, or it can be laminated with the magnetic layer by coating the magnetic layer with an adhesive layer-forming composition and drying it. The metal layer can be incorporated into the electromagnetic shielding material as a layer that is in direct contact with the adhesive layer, for example, by bonding it to the adhesive layer. Furthermore, in the electromagnetic shielding material described above, two adjacent layers can be bonded together by applying pressure and heat, for example. A flat plate press, a roll press, etc., can be used for bonding. For example, when a magnetic layer is placed as a layer in direct contact with a metal layer, the magnetic layer softens during the bonding process, promoting contact with the surface of the metal layer, thereby bonding the two adjacent layers together. The pressure during bonding can be set arbitrarily. In the case of a flat plate press, for example, 1 to 50 N / mm 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. For a flat plate press, for example, it is 5 seconds to 30 minutes. For 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 20°C or higher and 200°C or lower.

[0061] The electromagnetic shielding material described above can be incorporated into electronic components or electronic devices in any shape. The electromagnetic shielding material can be in sheet form, and its size is not particularly limited. In this invention and specification, "sheet" is synonymous with "film". Furthermore, the electromagnetic shielding material can be a three-dimensional molded product obtained by three-dimensionally molding a sheet-like electromagnetic shielding material, or it can be a sheet-like electromagnetic shielding material for three-dimensional molding. Various molding methods such as die press molding, vacuum forming, and pressure forming can be used as the three-dimensional molding method. Among these, since the electromagnetic shielding material has excellent formability for cold forming, it is preferable to apply cold forming such as deep drawing and stretch forming to the electromagnetic shielding material. Deep drawing is a molding method in which a sheet-like object to be molded is pressed using a pair of molds, a female and a male, to form a bottomed container of various shapes such as a cylinder, a rectangular tube, or a cone. In contrast, stretch forming is a method of forming a molded product in which a curved surface protrudes from a flat surface from a sheet-like object to be molded. Stretch forming can also be performed by pressing with only a male mold without a female mold. Deep drawing is broadly classified into deep drawing and shallow drawing. Shallow drawing produces molded products with shallow depth, while deep drawing produces molded products with greater depth (for example, deeper than the diameter of a cylinder or cone, or the length of one side of a pyramid). The electromagnetic shielding material described above can be an electromagnetic shielding material that is resistant to breakage when formed by such a three-dimensional molding method. Known techniques can be applied to the three-dimensional molding method.

[0062] [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, for example, be three-dimensionally molded into any shape according to the shape of the electronic component and placed inside the electronic component, or it can be three-dimensionally molded into the shape of a cover material that covers the outside of the electronic component and placed as a cover material. Alternatively, it can be three-dimensionally molded into a cylindrical shape and placed as a cover material that covers the outside of a cable.

[0063] [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 them. 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 formed into a cylindrical shape and placed as a cover material that covers the outside of a cable.

[0064] 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. In one embodiment, the above-mentioned electromagnetic shielding material can have one or both outermost layers as metal layers, so it can be suitably used when performing the above-mentioned wiring. [Examples]

[0065] 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.

[0066] [Resin for the magnetic layer] The resins used for the magnetic layers shown in Table 1 are as follows. In Table 1, polyester urethane resin is abbreviated as "polyester urethane," silicone resin as "silicone," and polyurethane resin as "polyurethane." The polyester urethane resin with a glass transition temperature (Tg) of -30°C is UR-6100, manufactured by Toyobo Co., Ltd. The polyester urethane resin with a glass transition temperature (Tg) of -11°C is a mixture of Toyobo's UR-8300 and Toyobo's UR-8700 in a mass ratio of 1:3. The polyester urethane resin with a glass transition temperature (Tg) of 23°C is UR-8300, manufactured by Toyobo Co., Ltd. The silicone resin with a glass transition temperature (Tg) of -13°C is KE-541-U silicone rubber manufactured by Shin-Etsu Silicone Co., Ltd. The polyester urethane resin with a glass transition temperature (Tg) of 73°C is UR-8200, manufactured by Toyobo Co., Ltd. The polyurethane resin with a glass transition temperature (Tg) of -50°C is Nipponran 5120, manufactured by Tosoh Corporation.

[0067] The glass transition temperatures of the resins shown in Table 1 were determined by the following method. The same resin (pellet or powder sample) used in the preparation of the magnetic layer forming composition (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

[0068] [Example 1] <Preparation of magnetic layer forming composition (coating solution)> In a plastic bottle, Fe-Si-Al flattened magnetic particles (Sendust MFS-SUH, manufactured by MKT Corporation) 36g Polyester urethane resin (see Table 1, solid content concentration 45% by mass) 20g Polyfunctional isocyanate (Tosoh Corporation's Coronate 3041) 0.45g Cyclohexanone 84g The mixture was added and mixed in a shaking stirrer for 1 hour to prepare the coating solution.

[0069] <Fabrication of magnetic layers> (Deposition of magnetic layer) A coating solution was applied to the release surface of a release-treated PET film (PET75TR manufactured by Nipper Co., Ltd., hereinafter referred to as "release film") 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 60 minutes to form a film-like magnetic layer. Subsequently, as a curing treatment, the magnetic layer on the release film was heat-treated by holding the release film together with the magnetic layer in a drying apparatus at an internal ambient temperature of 60°C for 48 hours to cause a crosslinking reaction between the polyester urethane resin and the polyfunctional isocyanate contained in the magnetic layer.

[0070] (Pressurization treatment of the magnetic 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 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 layer was removed along with the release film.

[0071] <Fabrication of shielding material> Iwatani Corporation's MK6G (labeled "MK6G" in Table 1) was used as a double-sided tape with adhesive layers on both sides of the support. The above double-sided tape is composed of five layers: a release (lightly peelable) polyethylene terephthalate (PET) film, an adhesive layer (layer containing acrylic adhesive), a PET film (support (glass transition temperature Tg: 70°C, determined by the method described above as the method for measuring the glass transition temperature of the resin layer)), an adhesive layer (layer containing acrylic adhesive), and a release (strongly peelable) PET film. The two adhesive layers on both sides of the support are both layers corresponding to the adhesive layers described above. After peeling off the release film, a sample piece for the following permeability measurement and electrical conductivity measurement evaluation was cut out from a part of the magnetic layer. One side of the magnetic layer after cutting out the sample piece was brought into contact with the adhesive layer exposed by peeling off the light-release PET film from the above double-sided tape, and the double-sided tape and the magnetic layer were bonded together. Then, the strong-release PET film of the above double-sided tape was peeled off to obtain an electromagnetic wave shielding material in the form of a sheet composed of four layers of a magnetic layer, an adhesive layer, a PET film (resin layer), and an adhesive layer, having these four layers in this order. The PET film contained in the obtained electromagnetic wave shielding material is mainly composed of resin, and the resin content is 90% by mass or more.

[0072] <Measurement of Permeability> The above magnetic layer was cut out into a rectangle with a size of 28 mm × 10 mm, and the permeability was measured using a permeability measuring device (Per01 manufactured by Keycom Co., Ltd.), and the permeability was determined as the real part (μ’) of the complex relative permeability at a frequency of 3 MHz. The obtained permeability was the value shown in Table 1. The evaluation results A, C, and D of the permeability shown in Table 1 are based on the following evaluation criteria. A: Permeability μ’ is 100 or more C: Permeability μ’ is 40 or more and less than 100 D: Permeability μ’ is less than 40

[0073] <Measurement of Electrical Conductivity> A cylindrical main electrode with a diameter of 30 mm was connected to the negative electrode side of a digital ultra-insulation resistance meter (TR-811A manufactured by Takeda Riken), a ring electrode with an inner diameter of 40 mm and an outer diameter of 50 mm was connected to the positive electrode side, and the main electrode and the ring electrode were installed on the sample piece of the above magnetic layer cut to a size of 60 mm × 60 mm at a position surrounding it. A voltage of 25 V was applied to both electrodes, and the surface resistivity of the magnetic layer alone was measured. The electrical conductivity of the magnetic layer was calculated from the surface resistivity and the following formula. The calculated electrical conductivity was 1.1×10 -2 S / m. As the thickness, the thickness of the magnetic layer obtained by the following method was used. Electrical conductivity [S / m] = 1 / (Surface resistivity [Ω] × Thickness [m])

[0074] <Acquisition of cross-sectional image of shield material> The cross-sectional processing to expose the cross-section of the shielding material in Example 1 was performed using the following method. 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. Using the scale bar as a reference, the thickness of each of the four layers—magnetic layer, adhesive layer, PET film (resin layer), and adhesive layer—was measured at five points, and the arithmetic mean of these measurements was taken as the thickness of the magnetic layer, the thickness of each of the two adhesive layers, and the thickness of the PET film (resin layer). The thickness of the magnetic layer was 30 μm, the thickness of each of the two adhesive layers was 2 μm, and the thickness of the PET film (resin layer) was 2 μm.

[0075] <Acquisition of cross-sectional images of the magnetic layer> Similarly to the above, the cross-section of the shielding material of Example 1, which was exposed by cross-sectional processing, was observed using a scanning electron microscope (SU8220, Hitachi High-Tech Corporation) under conditions of an acceleration voltage of 2kV and a magnification of 1000x to obtain a backscattered electron image.

[0076] <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. When it was determined whether or not the magnetic layer contained flattened particles as magnetic particles, as described earlier, it was determined that the magnetic layer contained flattened particles. Furthermore, the degree of orientation of the magnetic particles identified as flattened was determined to be 13° by the method described earlier. In addition, the average value (arithmetic mean) of the aspect ratios of all particles identified as flattened was calculated as the aspect ratio of the flattened particles contained in the magnetic layer. The calculated aspect ratio was 0.071.

[0077] <Peak top temperature of Tanδ, E’ at 60°C> A measurement sample with a length of 28 mm and a width of 10 mm was cut out from the electromagnetic wave shielding material, and dynamic viscoelasticity measurement was performed according to the measurement procedure described above using a dynamic viscoelasticity measuring device DMS6100 manufactured by Hitachi High-Tech Sciences Corporation as the dynamic viscoelasticity measuring device. From the obtained measurement results, the peak top temperature of the loss tangent Tanδ and E’ at 60°C in the dynamic viscoelasticity measurement at 1 Hz were determined.

[0078] <Formability> The electromagnetic wave shielding material was used to produce a hemispherical three-dimensional molded product by drawing and molding in a room temperature (25°C) environment without heating using a mold (manufactured by Amada Co., Ltd.) consisting of a male mold and a female mold. The presence or absence of breakage in the produced three-dimensional molded product was visually confirmed, and the formability was evaluated according to the following evaluation criteria from the confirmation results. (Evaluation criteria) A: It is possible to mold a three-dimensional molded product with a depth of 3 cm without breakage using a hemispherical mold with a depth of 3 cm. B: It is possible to mold a three-dimensional molded product with a depth of 2 cm without breakage using a hemispherical mold with a depth of 2 cm. Furthermore, when using a hemispherical mold with a depth of 3 cm, was there breakage in the obtained three-dimensional molded product with a depth of 3 cm, or a three-dimensional molded product with a depth of 3 cm could not be obtained. C: It is possible to mold a three-dimensional molded product with a depth of 1 cm without breakage using a hemispherical mold with a depth of 1 cm. Furthermore, when using a hemispherical mold with a depth of 2 cm, was there breakage in the obtained three-dimensional molded product with a depth of 2 cm, or a three-dimensional molded product with a depth of 2 cm could not be obtained. D: There is breakage in the obtained three-dimensional molded product with a depth of 1 cm using a hemispherical mold with a depth of 1 cm.

[0079] <Tensile test (elongation rate)> A measuring sheet measuring 50 mm in length and 10 mm in width was cut from the electromagnetic shielding material mentioned above. Tensile tests were performed on this measuring sheet using an A&D Company, Limited Tensilon universal material tester (RTF-1310) under the following measurement conditions to determine the elongation. The elongation is calculated as follows: Elongation [unit: %] = 100 × L / distance between chucks, where L is the maximum elongation of the test sheet stretched during the tensile test (i.e., the elongation displacement in the length direction at the point when at least one layer of the measuring sheet breaks). The breakage of at least one layer can be determined by the stress decrease in the stress-strain curve, visual inspection, etc. The elongation rate obtained in this way is preferably 1.0% or higher from the viewpoint of formability (e.g., formability in cold forming), more preferably 2.0% or higher, even more preferably 5.0% or higher, and even more preferably 10.0% or higher. Furthermore, the above elongation rate can be, for example, 90.0% or less, 80.0% or less, 70.0% or less, or 60.0% or less, or may exceed the values ​​exemplified herein. (Measurement conditions) Chuck spacing: 25mm Measurement environment: Temperature 23°C, relative humidity 50% Load cell: 500N (Newtons) Tensile speed: 1 mm / min Tensile direction: Length direction

[0080] [Examples 2-11, Comparative Examples 2, 3] Except for the changes made to the items shown in Table 1 and the adjustment of the amount of polyfunctional isocyanate used in the preparation of the magnetic layer-forming composition to 5% by mass relative to the solid content of the resin used (i.e., 5 parts by mass per 100 parts by mass of resin), the electromagnetic shielding material was prepared and various evaluations were performed using the method described for Example 1. For the examples and comparative examples, which differ from Example 1 in terms of the resin content of the magnetic layer, the resin content of the magnetic layer was changed by altering the amount of resin in the magnetic layer forming composition described above. For the electromagnetic shielding materials of Examples 2, 3, 6-8, 10, 11 and Comparative Example 2, the thickness of each layer was determined using the method described above, and the thickness of each layer was the same as the value obtained for Example 1. The electromagnetic shielding materials for Examples 5, 9, and Comparative Example 3, which are listed as "none" in the adhesive sheet column of Table 1, are electromagnetic shielding materials consisting of only one magnetic layer. For the above examples and comparative examples, the thickness of the magnetic layer was determined to be 30 μm using the method described above. The adhesive tape used in Example 4 was Lintec's NCF-D692(5) adhesive tape (referred to as "D692" in Table 1). This adhesive tape is a three-layer adhesive tape having an adhesive layer (acrylic adhesive-containing layer) between two release films, and does not include a support. The adhesive layer of the above adhesive tape corresponds to the adhesive layer described above. In Example 4, a magnetic layer was prepared as described in Example 1, and a sample piece for evaluating the magnetic permeability measurement was cut out from a part of the magnetic layer after peeling off the release film. One side of the magnetic layer after cutting out the sample piece was brought into contact with the adhesive layer exposed by peeling off one of the release films of the above adhesive tape, and the adhesive tape and the magnetic layer were bonded together. Then, the other release film was peeled off to obtain the electromagnetic wave shielding material of Example 4, which consists of two layers: a magnetic layer and an adhesive layer. When the thickness of each layer was determined by the method described above, the thickness of the magnetic layer was 30 μm and the thickness of the adhesive layer was 5 μm.

[0081] [Example 12] Except for the method used to deposit the magnetic layer, the electromagnetic shielding material was fabricated and various evaluations were performed using the method described for Example 1. For the electromagnetic shielding material of Example 12, the thickness of each layer was determined using the method described above, and the thickness of each layer was the same as that determined for Example 1.

[0082] <Preparation of magnetic layer forming composition (coating solution)> In a plastic bottle, Fe-Si-Al flattened magnetic particles (Sendust MFS-SUH, manufactured by MKT Corporation) 12g Silicone resin (see Table 1) 1g Hardener (Shin-Etsu Silicone Co., Ltd. C-8) 0.02g Methyl ethyl ketone 14g Cyclohexanone 14g The mixture was added and mixed in a shaking stirrer for 12 hours to prepare the coating solution.

[0083] <Fabrication of magnetic layers> (Deposition of magnetic layer) A coating solution was applied to the peeled surface of a pre-released PET film (PET75TR manufactured by Nippa Co., Ltd.) using a blade coater with a coating gap of 300 μm. The film was dried for 30 minutes in a drying apparatus with an internal ambient temperature of 80°C, and then cured for 12 hours at an internal ambient temperature of 150°C to form a magnetic film.

[0084] [Example 13] Except for the magnetic layer being fabricated using the method described below, the electromagnetic shielding material was fabricated and various evaluations were performed using the method described for Example 1. When the thickness of each layer of the electromagnetic shielding material of Example 13 was determined using the method described above, the thickness of each layer was the same as the value obtained for Example 1.

[0085] <Preparation of magnetic layer forming composition (coating solution)> In a plastic bottle, Fe-Si-Al flattened magnetic particles (Sendust MFS-SUH, manufactured by MKT Corporation) 12g Polyurethane resin (Nipporan 5120, manufactured by Tosoh Corporation, solid content concentration 30% by mass) 3.3g Polyfunctional isocyanate (Takenate D101E, manufactured by Mitsui Chemicals, 75% solids by mass) 0.40g Cyclohexanone 25g The mixture was added and mixed in a shaking stirrer for 12 hours to prepare the coating solution. The amount of polyfunctional isocyanate in the prepared magnetic layer forming composition was 30 parts by mass per 100 parts by mass of resin.

[0086] <Fabrication of magnetic layers> (Deposition of magnetic layer) A coating solution was applied to the peeled surface of a pre-released PET film (PET75-JOL manufactured by Nipper Co., Ltd.) using a blade coater with a coating gap of 300 μm. The film was then dried for 30 minutes in a drying apparatus with an internal ambient temperature of 80°C to form a magnetic film on the pre-released PET film.

[0087] (Pressurization and heat treatment of the magnetic layer) The upper and lower press plates of a plate press machine (Toyo Seiki Mini Test Press) are heated to 140°C (internal temperature of the press plates), and the magnetic layer from which the above-mentioned peeled PET film has been removed is sandwiched between two 1mm thick Teflon® sheets and subjected to a pressure of 30 N / mm². 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 layer was removed from between the two Teflon® sheets. Subsequently, in order to cause a crosslinking reaction between the polyurethane resin and the polyfunctional isocyanate contained in the magnetic layer, the magnetic layer was heat-treated by holding it in a drying apparatus with an internal atmosphere temperature of 60°C for 48 hours to obtain the magnetic layer.

[0088] [Example 14] Prior to the pressurization treatment of the magnetic layer, the magnetic layer was heat-treated by holding it in a drying apparatus with an internal atmosphere temperature of 60°C for 48 hours to cause a crosslinking reaction between the polyurethane resin and the polyfunctional isocyanate contained in the magnetic layer. After this heat treatment, the magnetic layer was pressurized using the method described in Example 13, and no further heat treatment was performed after the pressurization treatment. Except for the points mentioned above, the electromagnetic shielding material was fabricated and various evaluations were performed using the method described for Example 13. When the thickness of each layer of the electromagnetic shielding material of Example 14 was determined using the method described above, the thickness of each layer other than the magnetic layer was the same as the value obtained for Example 13, and the thickness of the magnetic layer was 34 μm.

[0089] [Comparative Example 1] TDK's noise suppression sheet, product name FlexiShield (model number IFL16-30NB), consists of a magnetic sheet, double-sided tape, and a release liner, in that order. The sheet with the release liner removed was used as the electromagnetic wave shielding material for Comparative Example 1, and various evaluations were performed using the method described above.

[0090] The results are shown in Table 1. In the "Overall Evaluation" column of Table 1, the lower of the two evaluation results (formability and permeability) was adopted. For example, if the two evaluation results were A and C, the overall evaluation result was C.

[0091] [Table 1]

[0092] The results shown in Table 1 confirm that the electromagnetic shielding material of the example has high magnetic permeability of the magnetic layer, excellent shielding ability, and excellent moldability.

[0093] An electromagnetic wave shielding material consisting of four layers, a magnetic layer, an adhesive layer, a PET film, and another adhesive layer, was obtained by the method described in Example 1. The side of the magnetic layer of the electromagnetic shielding material that was not bonded to the adhesive layer was brought into contact with the adhesive layer exposed by peeling off the easily removable PET film from the double-sided tape (MK6G, manufactured by Iwatani Corporation), thereby bonding the double-sided tape and the magnetic layer. After removing the strong release PET film from the double-sided tape, a 10 μm thick copper foil (compliant with JIS H3100:2018 standard, alloy number C1100R, copper content of 99.90% by mass or more) was attached to the adhesive layer on the outermost surface of each side. Thus, an electromagnetic wave shielding material was obtained consisting of nine layers: a metal foil (metal layer), an adhesive layer, a PET film (resin layer), an adhesive layer, a magnetic layer, an adhesive layer, a PET film (resin layer), an adhesive layer, and a metal foil (metal layer), with these nine layers included in this order. The shielding performance of the obtained electromagnetic wave shielding material was evaluated by the method described below, and it was found to be 14.5 dB at a frequency of 100 kHz and 73.2 dB at a frequency of 10 MHz, confirming that it has excellent shielding performance against magnetic fields. Furthermore, when the moldability of the obtained electromagnetic wave shielding material was evaluated as described above, the same evaluation results as in Example 1 were obtained.

[0094] <Evaluation of shielding performance (KEC method)> A KEC method evaluation apparatus, including a signal generator, amplifier, a pair of magnetic 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 at frequencies of 100kHz and 10MHz to determine the shielding capacity. This process was then performed for the magnetic field antennas to determine their magnetic field shielding capacity. KEC stands for Kansai Electronics Industry Promotion Center. [Industrial applicability]

[0095] One aspect of the present invention is useful in the technical fields of various electronic components and various electronic devices.

Claims

1. It has one or more magnetic layers containing magnetic particles and resin, An electromagnetic shielding material in which the peak top temperature of the loss tangent Tanδ in a 1 Hz dynamic viscoelasticity measurement is between 0°C and 60°C.

2. The electromagnetic wave shielding material according to claim 1, further comprising one or more adhesive layers.

3. The electromagnetic wave shielding material according to claim 2, further comprising a resin layer located between two adhesive layers.

4. It further has two or more metal layers, and An electromagnetic wave shielding material according to any one of claims 1 to 3, comprising one or more magnetic layers sandwiched between two metal layers.

5. An electromagnetic shielding material according to any one of claims 1 to 3, wherein the storage modulus E' in a dynamic viscoelastic measurement at 1 Hz is 0.010 GPa or more and less than 10.000 GPa at 60°C.

6. The electromagnetic wave shielding material according to any one of claims 1 to 3, wherein the magnetic layer comprises a resin having a urethane structure.

7. The peak top temperature of the loss tangent Tanδ in the dynamic viscoelasticity measurement at 1 Hz is 15°C or higher and less than 40°C, and An electromagnetic shielding material according to any one of claims 1 to 3, wherein the storage modulus E' in a dynamic viscoelastic measurement at 1 Hz is 0.010 GPa or more and less than 10.000 GPa at 60°C.

8. The electromagnetic wave shielding material according to any one of claims 1 to 3, wherein the magnetic layer includes flattened metal particles as the magnetic particles.

9. An electromagnetic wave shielding material according to any one of claims 1 to 3, which is in the form of a sheet.

10. An electronic component comprising an electromagnetic shielding material according to any one of claims 1 to 3.

11. An electronic device comprising an electromagnetic shielding material according to any one of claims 1 to 3.

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