Electronic interference suppression materials

Abstract

An electronic interference suppression material comprising a matrix material including at least one selected from organic and inorganic materials, and a carbon composite material, wherein the carbon composite material is at least one selected from a core-shell particle having a coating layer made of graphene with an average number of layers of 4 or less on the surface of an inorganic particle, and a core-shell connector having a coating layer made of graphene with an average number of layers of 4 or less on the surface of a connector of inorganic particles, and has a volume resistivity of 103 Ω·cm or more.

Description

Technology Field

[0001] The present disclosure relates to an electronic interference suppression material. Background Technology

[0002] Recently, various countermeasures are being implemented with the aim of reducing electronic interference, such as device malfunctions caused by electronic noise, information leakage, and the degradation of information and communication speeds due to interference. As means to reduce electronic interference, methods of blocking electromagnetic waves through reflection or absorbing electromagnetic waves have been proposed.

[0003] For example, Patent Document 1 proposes an electromagnetic shielding material formed by dispersing a soft magnetic metal powder, such as a metal selected from Fe, Ni, Co, and V or an alloy composed of two or more of these metals, in a matrix of rubber or plastic and molding it into a sheet. Patent Document 2 proposes a sheet-shaped electromagnetic wave absorber in which an electromagnetic wave absorption layer formed by an electromagnetic wave absorption material, in which silicon carbide powder is dispersed in a matrix resin, is laminated onto the surface of a metal body. Patent Document 3 proposes an electromagnetic wave absorbing sheet in a frequency band of 5 to 7 GHz, comprising a dielectric layer formed by a matrix including a carbon material, a divided conductive film layer laminated on one side of the dielectric layer, and an electromagnetic wave reflection layer laminated on the other side of the dielectric layer. Prior art literature

[0004] Japanese Patent Publication No. 2001-68889, Japanese Patent Publication No. 2005-57093, Japanese Patent Publication No. 2012-209515 The problem to be solved

[0005] Conventionally, many proposals aimed at reducing electromagnetic interference have been made, such as the electromagnetic shielding materials, electromagnetic wave absorbers, and electromagnetic wave absorbing sheets described in the aforementioned patent documents 1 to 3. However, due to the recent increase in performance and diversification of communication devices, there are cases where the reduction of electromagnetic interference is insufficient, and further improvements are required.

[0006] In addition, there was also the challenge that methods of blocking electromagnetic waves through reflection using metals, etc., could not avoid self-poisoning.

[0007] The present disclosure is made in consideration of these circumstances and aims to provide an electromagnetic interference suppression material having good electromagnetic wave absorption performance and electromagnetic interference suppression performance, and further performance in reducing electromagnetic interference. means of solving the problem

[0008] As a result of careful consideration to solve the above problem, the inventors discovered that an electromagnetic interference suppression material comprising a base material including at least one selected from organic and inorganic materials and a predetermined carbon composite material has high electromagnetic wave absorption performance and electromagnetic interference suppression performance, and has better performance in reducing electromagnetic interference.

[0009] The present disclosure is completed based on these findings.

[0010] That is, the present disclosure relates to the following.

[0011] [1] An electronic interference suppression material comprising a base material including at least one selected from organic and inorganic materials, and a carbon composite material,

[0012] The carbon composite material is at least one selected from core-shell particles having a coating layer made of graphene with an average number of layers of 4 or less on the surface of inorganic particles, and core-shell connectors having a coating layer of graphene with an average number of layers of 4 or less on the surface of a connector of inorganic particles.

[0013] The volume resistivity is 10 3Electron interference suppression material having a value of Ω·cm or greater.

[0014] [2] In [1],

[0015] An electronic interference suppression material having an average particle diameter of the inorganic particles having the core-shell particles and the inorganic particles having the core-shell linkage of 100 μm or less.

[0016] [3] In either [1] or [2],

[0017] An electronic interference suppression material having a graphene content of 0.001 to 30 mass% relative to the total electronic interference suppression material.

[0018] [4] In any one of [1] to [3],

[0019] An electronic interference suppression material comprising at least one selected from alumina, silica, magnesium oxide, tungsten carbide, and aluminum nitride, wherein the inorganic particle having the core-shell particle and the inorganic particle having the core-shell linker are included.

[0020] [5] In any one of [1] to [3],

[0021] An electronic interference suppression material in which the inorganic particles having the core-shell particles and the inorganic particles having the core-shell linkage are magnetic materials.

[0022] [6] [5] In this case,

[0023] An electronic interference suppression material comprising at least one selected from magnetic metals, magnetic metal alloys, and magnetic oxides, wherein the magnetic oxide is at least one selected from ferrites and magnetites.

[0024] [7] [6] In this case,

[0025] An electronic interference suppression material in which the above magnetic metal and magnetic metal alloy have a flat shape.

[0026] [8] In any one of [1] to [7],

[0027] An electronic interference suppression material in which the above organic material is a thermosetting resin.

[0028] [9] In any one of [1] to [7],

[0029] An electronic interference suppression material in which the above organic material is a thermoplastic resin.

[0030]

[10] In any one of [1] to [9],

[0031] An electronic interference suppression material in which the above-mentioned inorganic material is ceramics. Effects of the invention

[0032] According to the present disclosure, an electromagnetic interference suppression material can be provided that has high electromagnetic wave absorption performance and electromagnetic interference suppression performance, and further reduces electromagnetic interference performance. Specific details for implementing the invention

[0033] Hereinafter, the present disclosure will be described in detail with reference to one embodiment.

[0034] In this specification, the notation "XX to YY" means "XX or greater and YY or less." Furthermore, in this specification, regarding numerical ranges (e.g., ranges of content, etc.), the lower and upper limits described in steps may each be combined independently. Additionally, regarding numerical ranges described in this specification, the upper or lower limit of the numerical range may be substituted with the values ​​shown in the examples.

[0035] In this specification, "electronic interference suppression material" refers to a material capable of dampening nearby electromagnetic fields and electromagnetic waves by utilizing loss characteristics (magnetic loss, dielectric loss, electrical resistance, etc.).

[0036] In this specification, "graphene" refers to "10 layers or less sp 2 It means "sheet-like material of bonded carbon atoms."

[0037] In this specification, the "average number of layers" of graphene is a value obtained by the following formula. Specifically, it is obtained by the method described in the examples below.

[0038] Average number of graphene layers = Carbon loading per area (g / m²) / (Mass of graphene per area [g / m²])

[0039] In addition, the "carbon loading per area (g / m²)" is a value obtained by dividing the carbon loading (g) of the carbon composite material per mass, determined by thermogravimetric analysis, by the specific surface area (m² / g) of the inorganic particles in the core-shell particles or the inorganic particles in the core-shell linkage. Specifically, the carbon loading (g) of the carbon composite material per mass, determined by thermogravimetric analysis, is obtained by the method described in the examples.

[0040] The above specific surface area refers to the BET specific surface area, and is a value obtained by measuring the BET multi-point method (e.g., 5 to 6 points) by nitrogen adsorption.

[0041] In this specification, "volume resistance" refers to volume resistivity, which can be measured in accordance with JIS K-6911:2006, and specifically, can be measured by the method described in the examples.

[0042] [Electronic interference suppression materials]

[0043] The electron interference suppression material of the present disclosure comprises a matrix material comprising at least one selected from organic and inorganic materials, and a carbon composite material. The carbon composite material is at least one selected from core-shell particles in which a coating layer made of graphene with an average number of layers of 4 or less is coated on the surface of inorganic particles, and a core-shell connector in which a coating layer of graphene with an average number of layers of 4 or less is coated on the surface of a connector of inorganic particles, and the electron interference suppression material has a volume resistivity of 1.0 × 10⁻⁶ 3 It is greater than Ω·cm.

[0044] The above-mentioned carbon composite material is at least one selected from a core-shell particle having a coating layer of graphene having an average number of layers of 4 or less on the surface of an inorganic particle, and a core-shell connector having a coating layer of graphene having an average number of layers of 4 or less on the surface of a connector of inorganic particles. The resulting electron interference suppression material has high electromagnetic wave absorption performance and electron interference suppression performance, and has better performance in reducing electron interference. Although the reason is not certain, it is thought to be as follows.

[0045] The carbon composite material of the present disclosure has a coating layer made of graphene having an average number of layers of 4 or less coated on the surface of an inorganic particle. In other words, the carbon composite material of the present disclosure has a graphene sheet (shell) having an average number of layers of 4 or less that is three-dimensionally continuous on the surface of an inorganic particle (core). Therefore, the carbon composite material has a large specific surface area and high electromagnetic wave absorption performance per unit volume as a carbon composite material. As such, due to the large specific surface area, the carbon composite material of the present disclosure can improve volume resistivity compared to cases containing the same amount of other carbon composite materials. Thus, by having a large specific surface area and an effect of improving volume resistivity, it is believed that the carbon composite material of the present disclosure has high electromagnetic wave absorption performance and electromagnetic interference suppression performance.

[0046] The coating layer of the core-shell particles and the coating layer of the core-shell linkage may be made of graphene. In order to increase the specific surface area of ​​the carbon composite material and further improve electromagnetic wave absorption performance and electromagnetic interference suppression performance, the average number of graphene layers may be less than 4, 3 or less, 2.5 or less, 2.0 or less, or 1.9 or less.

[0047] The electronic interference suppression material of the present disclosure has a volume resistivity of 1.0 × 10⁻⁶ 3 It is greater than Ω·cm.

[0048] It is generally said that it is difficult for electromagnetic interference suppression materials to possess insulation, electron absorption performance, and electromagnetic interference suppression performance simultaneously. However, the electromagnetic interference suppression material of the present disclosure includes the carbon composite material described above, thereby possessing high insulation (volume resistivity) while also enhancing electromagnetic wave absorption performance and electromagnetic interference suppression performance.

[0049] In one embodiment of the present disclosure, with respect to ensuring insulation, the volume resistivity is 10 6 It may be Ω·cm or greater, and 10 8 It may be Ω·cm or greater, and 10 10 It may be Ω·cm or greater. No specific upper limit is formed, but 1.0×10 16 It may be Ω㎝ or less.

[0050] Communication devices can generate significant heat, and generally, a heat dissipation mechanism, such as a heat dissipation sheet, is required. If an electromagnetic interference suppression material not only reduces electromagnetic interference but also has high thermal conductivity and heat dissipation properties, there is no need to use other mechanisms, such as heat dissipation sheets. This is useful because, in addition to miniaturizing and lightening electronic components, it also allows for a reduction in assembly time. In this regard, the thermal conductivity of the electromagnetic interference suppression material may be 0.1 to 10.0 W / m·K, 0.5 to 8.0 W / m·K, or 1.0 to 6.0 W / m·K.

[0051] In addition, the above thermal conductivity can be obtained by the hot wire method, which is determined by comparing the temperature gradient when heat flow energy is provided by a hot wire with a sample whose thermal conductivity is already known, or by the laser flash method, which calculates the thermal conductivity based on the thermal diffusivity and specific heat measured at that time by instantaneously applying high energy, such as a laser, to a homogeneous material. Specifically, it can be measured by the method described in the examples.

[0052] As communication devices become smaller and lighter, there is a demand for packaging materials that use electromagnetic interference suppression materials. For example, packages of module-type electronic components are asymmetric thin and some have large surface areas. In a packaging process where electronic components on a large substrate, such as FOWLP (Fan Out Wafer Level Package), are sealed on one side and then reassembled, it is necessary to reduce warping. In such cases, it is useful to bring the thermal expansion of the electromagnetic interference suppression material as close as possible to that of an insert with a low coefficient of thermal expansion, that is, to make the electromagnetic interference suppression material low in thermal expansion. From this perspective, the coefficient of thermal expansion of the electromagnetic interference suppression material (α1: coefficient of thermal expansion between room temperature (25°C) and the glass transition temperature) may be 1 ppm / deg. or higher, or 3 ppm / deg. or higher. Additionally, the coefficient of thermal expansion of the electromagnetic interference suppression material may be 40 ppm / deg. or lower, or 35 ppm / deg. or lower. When the above-mentioned electronic interference suppression material is used as a sealant, the thermal expansion coefficient of the above-mentioned electronic interference suppression material may be 22 ppm / deg. or less, or 20 ppm / deg. or less.

[0053] In addition, the above coefficient of thermal expansion can be obtained from the slope of the tangent line at 25 to 60°C on a TMA chart obtained from measurements by Thermal Mechanical Analysis (TMA). Specifically, it can be measured by the method described in the example.

[0054] Carbon Composite Materials

[0055] The carbon composite material of the present disclosure is at least one selected from a core-shell particle having a coating layer made of graphene with an average number of layers of 4 or less on the surface of an inorganic particle, and a core-shell connector having a coating layer made of graphene with an average number of layers of 4 or less on the surface of a connector of inorganic particles.

[0056] In addition, the carbon composite materials of the present disclosure include those in which the pores of inorganic particles are coated with carbon, or those in which carbon is filled into the pores of inorganic particles.

[0057] The average particle diameter of the above core-shell particles may be 0.0005 to 100 μm, 0.1 to 50 μm, or 0.5 to 20 μm in order to further improve ease of manufacturing, electromagnetic wave absorption performance, and electromagnetic interference suppression performance.

[0058] In addition, the average particle diameter of the core-shell particles is a value obtained from the following formula, assuming a cylindrical pore shape.

[0059] Average particle diameter of core-shell particles (m) = 6 / [Specific surface area (m² / g) × True density of core-shell particles (g / m³)]

[0060] The above specific surface area refers to the BET specific surface area, and is a value obtained by measuring the BET multi-point method (e.g., 5 to 6 points) by nitrogen adsorption.

[0061] The average particle diameter of the above-mentioned core-shell connector may be 0.0005 to 100 μm, 0.1 to 50 μm, or 0.5 to 20 μm in order to further improve ease of manufacturing, electromagnetic wave absorption performance, and electromagnetic interference suppression performance.

[0062] In addition, the average particle diameter of the above-mentioned core-shell connector can also be estimated by using a laser diffraction particle size distribution system.

[0063] The average particle diameter of the above carbon composite material may be 100 μm or less in order to further improve electromagnetic wave absorption performance and electromagnetic interference suppression performance. In addition, in this specification, "average particle diameter of the carbon composite material" refers to the average particle diameter of primary particles when the carbon composite material is not aggregated and is a primary particle, and refers to the average particle diameter of secondary particles when the carbon composite material is aggregated and forms secondary particles.

[0064] In addition, the method for measuring the average particle diameter of the carbon composite material described above is a value calculated from the volume and specific surface area of ​​the holes, estimated by a laser diffraction particle size distribution system, or as the average value of the particle diameters of particles observed in 20 to 100 fields of view using observation means of a scanning electron microscope (SEM) or a transmission electron microscope (TEM). In addition, "particle diameter" refers to the maximum distance between any two points passing through the center of the particle and on the outline of the particle.

[0065] The specific surface area of ​​the above carbon composite material may be 800 m² / g or less, 780 m² / g or less, or 600 m² / g or less in terms of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance. Although no lower limit is specifically formed, it may be 1 m² / g or more, 5 m² / g or more, or 10 m² / g or more.

[0066] In addition, the above specific surface area refers to the BET specific surface area, and is a value measured by the BET multi-point method based on nitrogen adsorption.

[0067] In the present disclosure, the content (mass%) of the carbon composite material in the electromagnetic interference suppression material is not particularly limited as it varies significantly depending on the application and the base material. In order to further improve electromagnetic wave absorption performance and electromagnetic interference suppression performance, the content (mass%) of the carbon composite material in the electromagnetic interference suppression material may be 0.1 to 90 mass%, 0.5 to 35 mass%, or 1 to 30 mass% with respect to the total amount of the electromagnetic interference suppression material.

[0068] [Inorganic Particles]

[0069] The core-shell particles and core-shell linkages of the present disclosure have inorganic particles. The inorganic particles having the core-shell particles and the inorganic particles having the core-shell linkages (hereinafter collectively referred to as "inorganic particles") are not particularly limited. Examples include inorganic particles such as alumina, silica, magnesium oxide, tungsten carbide, aluminum nitride, cerium oxide, titanium oxide, and calcium carbonate; magnetic materials such as magnetic metals such as pure iron; amorphous magnetic metal alloys; Ni-Fe alloys; magnetic materials such as mild steel, silicon steel (Fe-Si alloys), Fe-Al alloys, Fe-Si-Al alloys (Sendust); and Co-Fe alloys; and magnetic materials such as magnetic oxides such as carbonyl iron, magnetite, and ferrite.

[0070] Specifically, examples of the above ferrite include Mn-Zn ferrite, Ni-Zn ferrite, Cu-Zn ferrite, Cu-Zn-Mg ferrite, Mn-Mg-Al ferrite, Y-type hexagonal ferrite, Z-type hexagonal ferrite, M-type hexagonal ferrite, etc.

[0071] The magnetic metal and the magnetic metal alloy may have a flat shape.

[0072] The above inorganic particles may be selected according to the application of the electronic interference suppression material.

[0073] The above inorganic particles may include at least one selected from alumina, silica, magnesium oxide, tungsten carbide, and aluminum nitride for the purpose of improving volume resistance, may include at least one selected from alumina, silica, and magnesium oxide, and may include alumina.

[0074] In addition, the above-mentioned inorganic particles may include silica in terms of thermal expansion coefficient.

[0075] In addition, the above-mentioned inorganic particles may include one selected from alumina, magnesium oxide, and aluminum nitride in terms of thermal conductivity, and may include alumina.

[0076] In addition, the above-mentioned inorganic particles may be magnetic materials in terms of improving electromagnetic wave absorption ability over a wide frequency range along with improving thermal conductivity, and the above-mentioned magnetic materials may include at least one selected from magnetic metals, magnetic metal alloys, and magnetic oxides, may include amorphous magnetic metal alloys, may include at least one selected from Fe-Si-Al alloys (Sendust), ferrite, and magnetite, and may include at least one selected from ferrite and magnetite.

[0077] The above-mentioned inorganic particles may consist of only one type, or may include two or more types.

[0078] The above-mentioned inorganic particles may be nanoparticles in order to further improve electromagnetic wave absorption performance and electronic interference suppression performance.

[0079] [Graphene]

[0080] The graphene of the present disclosure is a sheet-like material having a hexagonal lattice structure in which carbon atoms are bonded. The graphene may be in a single-layer state having a layer thickness of one carbon atom, or in a multilayer state of two or more layers. In addition to carbon atoms, the graphene may include oxygen atoms, hydrogen atoms, boron atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, etc.

[0081] The content (mass%) of graphene in the core-shell particles and the core-shell linkage is not particularly limited. In order to further improve electromagnetic wave absorption performance and electromagnetic interference suppression performance, it may be 0.1 to 70 mass%, 0.5 to 45 mass%, or 1 to 20 mass%.

[0082] There is no particular limit on the content (mass%) of graphene in the above-mentioned electronic interference suppression material. In order to further improve electromagnetic wave absorption performance and electronic interference suppression performance, it may be 0.001 to 30 mass%, 0.01 to 20 mass%, or 0.05 to 15 mass%.

[0083] <Material>

[0084] The base material of the present disclosure comprises at least one selected from organic and inorganic materials. The base material may comprise only organic materials, only inorganic materials, or both organic and inorganic materials.

[0085] [Organic matter]

[0086] The organic material included in the base material is not particularly limited, but examples include thermosetting resins, thermoplastic resins, etc.

[0087] Examples of thermosetting resins include epoxy resin, phenolic resin, imide resin, etc.

[0088] Examples of thermoplastic resins include polyolefin resins, vinyl resins, styrene-acrylic resins, ethylene-acrylic acid ester resins, ethylene-methacrylic acid ester resins, diene resins, terpene resins, petroleum resins, cellulose resins, polyamide resins, polyurethane resins, polyester resins, polycarbonate resins, polyimide resins, fluoropolymer resins, etc.

[0089] The above organic material may be a thermosetting resin from the perspective of reliability of a molded body using an electron interference suppression material, or an epoxy resin or an imide resin from the perspective of electrical insulation and heat resistance of a molded body using an electron interference suppression material. It may be a thermoplastic resin from the perspective of ease of manufacturing and processing, or a polyurethane from the perspective of durability and weather resistance, and for outdoor use, a polycarbonate-based polyurethane with good hydrolytic resistance may be used. Furthermore, the term "molded body" refers to a molded body manufactured by placing it into a mold, such as a casting or die.

[0090] The above organic material may be used as a single type, or a combination of two or more types may be used.

[0091] In the present disclosure, the epoxy resin used as an organic material has two or more epoxy groups in one molecule and is generally used as an electronic component, and its molecular structure, molecular weight, etc. are not particularly limited.

[0092] Examples of the above epoxy resins include, for instance, phenol novolak-type epoxy resins, cresol novolak-type epoxy resins, aliphatic epoxy resins such as dicyclopentadiene derivatives, and aromatic epoxy resins such as biphenyl-type, biphenyl-aralkyl-type, naphthyl-type, and bisphenol-type. These epoxy resins may be used as a single type or as a mixture of two or more types. There are no particular restrictions on the physical properties, and it may be either liquid or solid at room temperature (25°C). For instance, the above epoxy resin may be a solid cresol novolak-type epoxy resin. The above solid cresol novolak-type epoxy resin is available as a commercial product, and examples include N670 (manufactured by DIC Corporation). Additionally, for instance, the above epoxy resin may be a liquid epoxy resin, specifically examples include bisphenol A-type and bisphenol F-type resins. The liquid epoxy resin may be a liquid bisphenol A-type epoxy resin. Liquid bisphenol A type epoxy resins are available as commercial products, and examples include EPOMIK (registered trademark) R140 (manufactured by MITSUI CHEMICALS, INC.).

[0093] In addition, in the present disclosure, liquid epoxy resin refers to an epoxy resin that exhibits a liquid phase at 25°C.

[0094] The epoxy equivalent of the above epoxy resin may be 140 or more from the perspective of the thermomechanical properties of the molded body. In addition, it may be 200 or more from the perspective of electromagnetic wave absorption performance. As for the upper limit of the above epoxy equivalent, it may be 400 or less from the perspective of thermomechanical properties, or 380 or less.

[0095] The above epoxy resin is (R 1 Polyoxyalkylene structure represented by O)m and (R 2 It may be an epoxy resin having a polyoxyalkylene structure represented by O)n.

[0096] Here, R 1 and R 2 Each independently represents an alkylene group having 1 or more carbon atoms. m+n may be 1 or more and 50 or less, or 1 or more and 20 or less. Also, m may be 0 or more and 49 or less, or 0 or more and 19 or less. n may be 1 or more and 50 or less, or 1 or more and 20 or less.

[0097] R 1 and R 2 As for the alkylene group represented by, for example, an alkylene group having 1 to 6 carbon atoms is exemplified, and specifically, a methylene group, an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, a hexamethylene group, etc. are exemplified. From the perspective of electromagnetic wave absorption performance, the above alkylene group may be a methylene group or an ethylene group.

[0098] m R 1 In the O period, multiple R 1 The groups may be identical alkylene groups or alkylene groups with different carbon numbers. In addition, n R 2 In the O period, multiple R 2 The groups may be identical alkylene groups or alkylene groups with different carbon numbers.

[0099] Examples of epoxy resins having the above polyoxyalkylene structure include liquid epoxy resins having a bisphenol A backbone and polyethylene glycol diglycidyl ether. Examples of commercially available liquid epoxy resins having a bisphenol A backbone include RIKARESIN BEO-60E (manufactured by New Japan Chemical Co., Ltd.) represented by the following general formula (1), and examples of commercially available polyethylene glycol diglycidyl ether include EPOLITE 400E (manufactured by KYOEISHA CHEMICAL Co., LTD.) which has a compound represented by the following general formula (2) as a main component.

[0100]

[0101]

[0102] In the present disclosure, examples of imide resins used as organic materials include, for instance, bis-allyl-nadiimide. Bis-allyl-nadiimide is available as a commercial product, and examples include BANI-M (manufactured by Maruzen Petrochemical Co., Ltd.) and BANI-X (manufactured by Maruzen Petrochemical Co., Ltd.).

[0103] In the present disclosure, the content (mass%) of the organic material in the electromagnetic interference suppression material may be 0.1 to 40 mass%, 1 to 30 mass%, 3 to 25 mass%, or 5 to 20 mass% with respect to the total amount of the electromagnetic interference suppression material in order to further improve electromagnetic wave absorption performance and electromagnetic interference suppression performance.

[0104] When the above organic material includes a thermosetting resin, the electronic interference suppression material of the present disclosure may further contain a curing agent and a curing accelerator, etc.

[0105] Examples of the above curing agents include aliphatic amines, aromatic amines, dicyandiamides, dihydrazide compounds, acid anhydrides, phenolic resins, etc. One of these may be used, or two or more may be used in combination.

[0106] Examples of the above-mentioned curing accelerators include organic peroxides such as dicumyl peroxide and dibutyl peroxide; imidazole compounds such as 2-methylimidazole and 2-ethylimidazole; organic phosphorus compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, and triphenylphosphine; diazabicycloalkene compounds such as 1,8-diazabicyclo[5,4,0]undecene-7 (DBU) and 1,5-diazabicyclo(4,3,0)nonene-5; and tetraphenylboron compounds such as 2-ethyl-4-[methylimidazole tetraphenylborate]. These may be used individually or in combination of two or more types.

[0107] In one embodiment of the present disclosure, when the electronic interference suppression material of the present disclosure contains a curing agent, the content may be 0 to 150 mass%, 0 to 120 mass%, or 0 to 100 mass% with respect to 100 mass% of the thermosetting resin.

[0108] In another embodiment of the present disclosure, when the electronic interference suppression material of the present disclosure contains a curing agent, the content thereof may be 1 to 20 mass%, 2 to 18 mass%, or 3 to 15 mass% with respect to the total amount of the electronic interference suppression material.

[0109] In addition, when the electronic interference suppression material of the present disclosure contains a curing accelerator, the content thereof may be 0.01 to 10 mass%, 0.05 to 5 mass%, or 0.1 to 3 mass% with respect to the total amount of the electronic interference suppression material.

[0110] The electronic interference suppression material of the present disclosure may further include a dispersion aid. The dispersion aid is not particularly limited as long as it is a material for stably and highly dispersing fine particles in a matrix resin. Generally, the dispersion aid is a surfactant having functional groups of different reactivity within one molecule, and a coupling agent, etc. Examples of the dispersion aid include anionic surfactants such as carboxylic acid salts, cationic surfactants such as quaternary ammonium salts; coupling agents having amine-based functional groups and sulfide-based functional groups, cellulose nanofibers, etc.

[0111] The above cellulose nanofibers are bipolar microsolids that improve the dispersibility of the filler through their surfactant action. The cellulose nanofibers may also be highly dispersed in a liquid such as water or a thermosetting resin oligomer.

[0112] The average fiber length of the above cellulose nanofiber may be 1㎛ or more and 100㎛ or less in terms of workability and fluidity, or 5㎛ or more and 50㎛ or less.

[0113] The average fiber diameter of the above cellulose nanofiber may include aggregates and may be 1 nm or more and 1000 nm or less, or 4 nm or more and 500 nm or less. By making the average fiber diameter within the above range, the dispersibility of the carbon composite material can be increased, and as a result, the electronic interference suppression performance can be further improved.

[0114] In addition, the average fiber length and average fiber diameter of cellulose nanofibers can be measured using a scanning electron microscope (SEM) by the same operation as that used for the average fiber length and average fiber diameter of the carbon nanotubes described above.

[0115] Examples of commercially available coupling agents having the above-mentioned amine-based and sulfide-based functional groups include SUMILINK (registered trademark) 100 (manufactured by Sumitomo Chemical Co., Ltd.). Examples of commercially available cellulose nanofibers include ELLEX-S (manufactured by Daio Paper Corporation).

[0116] When the dispersion aid is included in the electronic interference suppression material of the present disclosure, the content thereof may be 0.1 to 30 mass%, 0.2 to 10 mass%, or 0.3 to 5 mass% with respect to the total amount of the electronic interference suppression material in terms of maintaining dispersibility and thermomechanical properties.

[0117] In addition to the above components, the electronic interference suppression material of the present disclosure may, as necessary, incorporate additives such as release agents, including synthetic waxes, natural waxes, higher fatty acids, and esters of higher fatty acids, which are generally incorporated into electronic interference suppression materials of this type, within a scope that does not deviate from the gist of the present disclosure; coloring agents such as cobalt blue; modifiers such as silicone oil and silicone rubber; hydrotalcites; ion capture agents; charge control agents; and flame retardants such as phosphazene. Each of these additives may be used as a single type, or two or more types may be mixed and used.

[0118] The content of each of these additives in the electronic interference suppression material of the present disclosure may be 0.05 to 30 mass% as the total amount of each additive with respect to the total amount of the electronic interference suppression material, or 0.2 to 20 mass%.

[0119] [Inorganic]

[0120] The inorganic material included in the base material is not particularly limited as long as it is an inorganic material used in electronic components, but the inorganic material (A) and inorganic material (B) described below are examples.

[0121] You may use one type of these, or you may use a combination of two or more types.

[0122] (Inorganic(A))

[0123] The inorganic material (A) is at least one selected from inorganic fillers such as silica, alumina, magnesium oxide, titanium oxide, barium titaniumate, silicon nitride, aluminum nitride, silicon carbide and tungsten carbide, amorphous magnetic metal alloys, Ni-Fe alloys, pure iron, mild steel, silicon steel (Fe-Si alloys), Fe-Al alloys, Fe-Si-Al alloys, Co-Fe alloys, soft magnetic materials such as carbonyl iron, magnetic oxides such as magnetite and ferrite, and is an inorganic material other than the inorganic material (B) described below.

[0124] The above inorganic material (A) may be used together with organic material. It may be at least one selected from silica and alumina for the purpose of reducing the coefficient of expansion of the electromagnetic interference suppressor or improving thermal conductivity, and may be silica. In addition, it may be at least one selected from ferrite and amorphous magnetic metal alloys for the purpose of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance.

[0125] The shape of the above-mentioned inorganic material (A) is not particularly limited, but examples include spherical, flake-like, fibrous, etc. The shape of the above-mentioned inorganic material may be spherical or may be other than spherical.

[0126] The average particle diameter of the above inorganic material (A) is not particularly limited, but may be 0.1㎛ or more and 100㎛ or less, 0.2㎛ or more and 75㎛ or less, or 0.2㎛ or more and 50㎛ or less.

[0127] In addition, in this specification, the average particle diameter is the volume average particle diameter, and the average particle diameter of the inorganic material (A) can be calculated as the average value of the major axis of the particles measured using a laser diffraction particle size distribution measuring device.

[0128] When the inorganic material (A) is included in the electronic interference suppression material of the present disclosure, the content thereof may be 20 to 95 mass%, 30 to 90 mass%, or 35 to 85 mass% with respect to the total amount of the electronic interference suppression material in order to further improve electromagnetic wave absorption performance and electronic interference suppression performance.

[0129] When the electron interference suppression material of the present disclosure is used as a sealing material for semiconductors, metal foreign matter is removed during the manufacturing process of the semiconductor sealing material. When metal foreign matter is removed using a magnet, the magnetic material is considered a foreign matter and is removed, resulting in a poor yield. In this regard, when the electron interference suppression material of the present disclosure is used as a sealing material for semiconductors, the content of the magnetic material may be 1 mass% or less, 0.5 mass% or less, or 0 mass% with respect to the total amount of the electron interference suppression material. Furthermore, since the magnetic material has a high specific gravity, the content of the magnetic material may be less than or equal to the above value from the perspective of reducing the weight of the resulting molded body.

[0130] (Inorganic(B))

[0131] Inorganic material (B) is ceramics.

[0132] The ceramics mentioned above are not particularly limited, but specifically, sintered bodies having metal oxides, nitrides, carbides, etc. as main components are exemplified.

[0133] Examples of oxides of the above metals include, specifically, alumina, zirconia, magnesium oxide, etc.

[0134] Examples of the nitrides of the above metals include, specifically, aluminum nitride, boron nitride, silicon nitride, etc.

[0135] Examples of the carbides of the above metals include, specifically, silicon carbide, boron carbide, etc.

[0136] The ceramics may be at least one sintered body selected from alumina and aluminum nitride.

[0137] [Method for manufacturing carbon composite materials]

[0138] Hereinafter, one form of a method for manufacturing a carbon composite material of the present disclosure is described, but the present disclosure is not limited to the following forms.

[0139] The carbon composite material according to the present disclosure can be manufactured, for example, by a method of coating a carbon layer onto inorganic particles.

[0140] (Inorganic particles)

[0141] As for the inorganic particles according to the present disclosure, the inorganic particles described in [Inorganic Particles] above are exemplified.

[0142] In the case where a carbon layer is coated on the inorganic particles of the present embodiment by CVD treatment, etc., the original structure may be stably maintained during CVD treatment, etc. For this reason, high heat resistance may be used.

[0143] The inorganic particles may be materials with a uniform structure and composition and particle size, and may also be materials capable of controlling the average number of graphene layers obtained to 4 or less in order to achieve a high specific surface area.

[0144] In this regard, the inorganic particles may be at least one selected from alumina, silica, magnesium oxide, tungsten carbide, aluminum nitride, and magnetic materials such as magnetic metals, magnetic metal alloys, and magnetic oxides. Additionally, in terms of improving electrical insulation performance, they may be alumina or silica, in terms of improving thermal conductivity and heat dissipation, they may be magnetic materials, and in terms of improving heat dissipation, they may be at least one selected from Fe-Si-Al alloys (sentust), ferrite, and magnetite.

[0145] The average particle diameter of the above-mentioned inorganic particles is not particularly limited, but the average particle diameter may be 0.0005 to 100 μm, 0.1 to 50 μm, or 0.5 to 20 μm. If the average particle diameter is 0.0005 μm or more, it is easy to handle and has good carbon coating properties. In addition, since the gas permeability of the carbon source is improved when coating the carbon source, uniform carbon coating becomes easy. On the other hand, if the average particle diameter is 100 μm or less, a carbon composite material with a high specific surface area (BET specific surface area) can be obtained.

[0146] The above inorganic particles may be used in combination with granular spacers. By using spacers, appropriate voids can be secured between the particles, preventing the particles from becoming too tightly packed and increasing pressure loss. As for the spacers, particles with an average particle diameter of, for example, 100 to 5000 μm may be used. The material of the spacers is not particularly limited as long as it can be sieved after carbon coating, and it may not decompose at 900 to 1000°C.

[0147] The mixing ratio of the particles and spacers is not particularly limited, but for example, the (particle:spacer) mass ratio may be 0.1:10 to 10:10 or 1:10 to 10:10. Within the above range, the carbon composite material can be obtained in a high yield.

[0148] (Covering of carbon layer)

[0149] The method of coating a carbon layer on the surface of inorganic particles is not particularly limited, and either a wet method or a dry method can be applied. In order to keep the average number of graphene layers 4 or less, a chemical vapor deposition (CVD) method may be used, or a method of introducing naphthalene molecules onto the surface of inorganic particles such as silica using a chemical formula and then calcining may be used.

[0150] The CVD method, used to introduce organic compounds and deposit a carbon layer on inorganic particles, is an industrial method for producing a thin film (e.g., a thin film made of carbon) composed of a specific element or elemental composition on a substrate such as inorganic particles. Typically, it is a technology that utilizes the process in which energy is applied to a gas containing raw materials by heat or light, or plasma-generated by high frequency, causing the raw materials to become radicalized and highly reactive through chemical reactions or thermal decomposition, and then adsorbed and deposited onto the substrate.

[0151] The organic compound used in the CVD method may be a gas at room temperature or capable of vaporization. Methods of vaporization include heating above the boiling point or reducing the atmospheric pressure. The organic compound used may be appropriately selected from carbon source materials. In particular, it may be a compound that undergoes thermal decomposition upon heating, or a compound capable of depositing a carbon layer on the surface of inorganic particles.

[0152] In addition, the organic compound used may be an organic compound containing hydrogen, oxygen, nitrogen, boron, sulfur, phosphorus, etc. This organic compound may be an organic compound containing unsaturated or saturated hydrocarbons, or a mixture thereof.

[0153] The organic compound used may be an unsaturated straight-chain or branched-chain hydrocarbon having double and / or triple bonds, a saturated straight-chain or branched-chain hydrocarbon, etc., or may be a saturated cyclic hydrocarbon, an aromatic hydrocarbon such as benzene, toluene, etc. As an organic compound, alcohols such as methanol and ethanol, or nitrogen-containing compounds such as acetonitrile and acrylonitrile may be used. Examples of organic compounds include acetylene, methylacetylene, ethylene, propylene, isoprene, cyclopropane, methane, ethane, propane, benzene, toluene, vinyl compounds, ethylene oxide, methanol, ethanol, acetonitrile, acrylonitrile, etc. One type of organic compound may be used alone, or two or more types may be used in combination. Among these, the organic compound used may be one that can enter the voids between particles, such as acetylene, ethylene, propylene, methane, ethane, etc., and may also be used for the purpose of precipitating highly crystalline carbon, such as methane, propylene, and benzene. In addition, methane may be used for the purpose of obtaining highly crystalline carbon due to the high thermal decomposition temperature.

[0154] The organic compound used for CVD at higher temperatures and for CVD at lower temperatures may be the same or different. For example, acetylene, ethylene, etc. may be used for CVD at lower temperatures, and propylene, isoprene, benzene, etc. may be used for CVD at higher temperatures.

[0155] When introducing an organic compound onto the above-mentioned inorganic particles, the inorganic particles may be subjected to reduced pressure beforehand, or the system itself may be subjected to reduced pressure. Any method in which carbon is deposited by CVD may be used. For example, carbon generated by the chemical reaction or thermal decomposition of an organic compound may be deposited (or adsorbed) onto alumina nanoparticles to coat the alumina nanoparticles with a carbon layer.

[0156] The pressure during CVD treatment is not particularly limited and, for example, may be 1 kPa to 200 kPa or 50 to 150 kPa. The heating temperature during CVD treatment should be a condition capable of forming a carbon layer of a few layers or less on the inorganic particles, and an appropriately suitable temperature can be selected depending on the organic compound used. The heating temperature may be 400 to 1500°C, 450 to 1100°C, or 550 to 950°C. For example, when propylene is used as the organic compound, the temperature may be 700 to 900°C, and when methane is used, the temperature may be 900 to 1100°C. However, a temperature approximately 50 to 200°C lower than the decomposition temperature of the organic compound is suitable. When heated above the decomposition temperature of organic compounds, gaseous carbon precipitation becomes pronounced, but by doing as described above, for example, unevenness in the amount of carbon deposited on the surface and inside the inorganic particles can be prevented and it can be deposited uniformly.

[0157] In addition, the heating temperature can be appropriately selected based on the CVD processing time and / or the pressure within the reaction system. Additionally, the product may be analyzed, and the temperature required to achieve the desired number of layers may be set based on the results.

[0158] The heating rate during CVD treatment is not particularly limited, but may be 1 to 50°C / min or 5 to 20°C / min. The treatment time during CVD treatment (CVD treatment time at a predetermined heating temperature) should be the time required to obtain graphene with an average number of layers of 4 or less, and an appropriately suitable time may be selected depending on the organic compound used and the temperature. For example, the treatment time during CVD treatment may be 5 minutes to 8 hours, 0.5 to 6 hours, or 1 to 5 hours. In addition, the time required for sufficient carbon deposition may be set based on the results of analyzing the product.

[0159] CVD treatment may be performed under reduced pressure, under vacuum, under pressurized conditions, or under an inert gas atmosphere. When performed under an inert gas atmosphere, examples of inert gases include nitrogen, helium, neon, argon, etc., and nitrogen may be used.

[0160] In the CVD method, carbon can be easily deposited or adsorbed onto particles in the gas phase by heating while passing a gaseous organic compound in contact with the particles along with a carrier gas. The type of carrier gas, flow rate, flow rate, and heating temperature are appropriately adjusted according to the type of organic compound used. The carrier gas may be, for example, the aforementioned inert gas, nitrogen, or a mixture with oxygen or hydrogen gas.

[0161] With respect to keeping the average number of graphene layers 4 or less, the flow rate of the carrier gas may be, for example, 0.05 to 1.0 m / min or 0.32 to 0.64 m / min. In addition, the amount of organic compound introduced may be 1 to 30 volume% or 5 to 20 volume% with respect to the total amount of the carrier gas and the organic compound.

[0162] As a method for coating a carbon layer on the above-mentioned inorganic particles, carbonization may be performed by introducing an organic compound through a wet method such as an impregnation method. Additionally, carbonization may be performed by impregnating the organic compound before introducing the organic compound and performing CVD. As for the organic compound to be impregnated, a thermal polymerizable monomer such as furfuryl alcohol, which has a high carbonization yield, may be used. For the method of impregnating the organic compound, known means may be employed, such as contacting the inorganic particles by bringing the organic compound into contact with the inorganic particles as is or mixed with a solvent if the organic compound is liquid, or by dissolving it in a solvent if it is solid.

[0163] After the first process, the carbon-coated inorganic particles may be heat-treated and the carbon layer carbonized to precipitate highly crystalline carbon on the surface of the inorganic particles. By doing so, the carbon composite material obtained becomes more highly crystalline and has a high specific surface area.

[0164] Since carbonization of the carbon layer can also be carried out by CVD treatment, the above heat treatment may be performed during CVD treatment or by other methods.

[0165] The method of heat treatment is not particularly limited, and heat treatment may be performed using a high-frequency induction furnace, etc.

[0166] By the above method, a core-shell particle and a core-shell linker, i.e., a carbon composite material, can be obtained, in which a coating layer made of graphene with an average number of layers of 4 or less is coated on the surface of an inorganic particle.

[0167] [Method for manufacturing electronic interference suppression material]

[0168] The electronic interference suppression material of the present disclosure may be obtained by sufficiently and uniformly mixing a carbon composite material and other components, which are blended as needed, using a mixer or the like, and then performing a mixing treatment using a disperser, kneader, three-stage roll mill, twin-axis heated roll, twin-axis heated extrusion mixing device, etc. The mixing treatment may be performed by heating. The temperature at that time may be 70°C or higher and 150°C or lower, or 75°C or higher and 120°C or lower.

[0169] The electronic interference suppression material of the present disclosure may be used after, for example, cooling and solidifying after the above-mentioned mixing process, and then crushing it to a suitable size using a cutting mill, ball mill, cyclone mill, hammer mill, vibration mill, cutter mill, grinder mill, speed mill, etc.

[0170] In addition, the mixture obtained after the above mixing treatment may be pressed in a molding machine under conditions of a temperature of 50°C or higher and 100°C or lower and a pressure of 0.5 MPa or higher and 1.5 MPa or lower to form a sheet.

[0171] The electronic interference suppression material of the present disclosure can be used as a radio wave absorbing material, a noise suppression sheet, a semiconductor sealing material, a sealing sheet, a wire sheathing material, etc.

[0172] As one embodiment of the present disclosure, for example, a semiconductor device fixed on a substrate can be sealed with a semiconductor device sealant comprising the electron interference suppression material of the present disclosure to obtain a resin-sealed electronic component.

[0173] In addition, known molding methods are used to obtain electronic components without being particularly limited. Low-pressure transfer molding is exemplified as the most common molding method, but molding by injection molding, die molding, compression molding, etc., is also possible.

[0174] For example, in the case of a transfer molding method, a heat treatment may be performed by a transfer molding machine at a temperature of 150°C or higher and 200°C or lower and a time of 20 seconds or higher and 200 seconds or lower, and the molded product may be withdrawn from the molding mold, and a heat treatment to complete curing may be performed at a temperature of 150°C or higher and 200°C or lower and a time of 2 hours or higher and 12 hours or lower.

[0175] In addition, in the case of the compression molding method, a substrate with a semiconductor device mounted thereon is first supplied to the upper mold of the molding die, and at the same time, the electron interference suppression material of the present disclosure is supplied into the cavity of the lower mold. Subsequently, by clamping both the upper and lower molds by the required clamping pressure, the substrate with the semiconductor device mounted thereon is immersed in the electron interference suppression material heated and melted within the lower mold cavity. After that, the electron interference suppression material heated and melted within the lower mold cavity is pressed by a cavity bottom member, and compression molding is performed by applying the required pressure under reduced pressure. The molding conditions may be a temperature of 120°C or higher and 200°C or lower, and a pressure of 2 MPa or higher and 20 MPa or lower.

[0176] Examples

[0177] Next, the present disclosure will be specifically described by way of examples, but the present disclosure is not limited in any way by these examples.

[0178] [Manufacturing of Carbon Composite Materials]

[0179] The details of the inorganic particles listed in Tables 1 and 2 used in the manufacture of carbon composite materials are as follows.

[0180] · Silica: SO-C1; Manufactured by Admatechs Co., Ltd., Average particle diameter: 0.3㎛

[0181] · Alumina: Puralox SBa-200; Manufactured by Sasol Limited, Average particle diameter (primary particle diameter): 7 nm

[0182] · Mesoporous silica: SBA-15 (prepared by the method described below)

[0183] · Magnesium oxide: Manufactured by EMJapan Co., Ltd., Average particle diameter (primary particle diameter): 10 nm

[0184] · Sendust (Fe-Si-Al alloy): Sanyo Special Steel Co., Ltd., Average grain diameter: 40㎛, Flat shape

[0185] · Ferrite (Mn-Zn system): Powdertech Co., Ltd., Average particle diameter: 5–10 µm,

[0186] <Preparation Example 1>

[0187] 2.3 g of 2,3-dihydroxynaphthalene (DN) was dissolved in 5 ml of acetone, and 0.47 g of dried silica (SO-C1) was added to obtain a mixture. This mixture was stirred at room temperature for 2 hours, and then the acetone was evaporated at 95°C. The residue of the mixture of DN and silica was heat-treated for 1 hour under a nitrogen stream at 573°C to react with the silica surface and DN, and then heat-treated for 4 hours under a nitrogen stream at 800°C to obtain carbon-coated silica particles (A-1).

[0188] <Preparation Example 2>

[0189] Alumina (Puralox SBa-200) and quartz sand (manufactured by SendaiWako Pure Chemical, Ltd.) as a spacer were mixed in a mass ratio of 3:20 (alumina nano: quartz sand). At this time, the quartz sand used was immersed in 1M hydrochloric acid for 12 hours, heated in air at 800°C in a muffle furnace for 2 hours, and sieved through a sieve with a mesh size of 180 μm. The mixture of alumina and quartz sand prepared above was placed in a reaction tube (inner diameter 37 mm), and chemical vapor phase growth CVD (methane CVD) using methane as a carbon source was performed. Specifically, under conditions where the flow rate of N2 gas was controlled to 224 ml / min, the mixture of alumina and quartz sand prepared above was heated from room temperature to 900°C at a heating rate of 10°C / min, maintained at 900°C for 30 minutes, then N2 gas (carrier gas) and methane gas were introduced into the reaction tube, and chemical vapor deposition (CVD) treatment was performed at 900°C for 2 hours. In addition, when introducing N2 gas and methane gas into the reaction tube, the amount of methane gas was controlled to 20 volume% relative to the total amount of N2 gas and methane gas, the flow rate of methane gas to 45 ml / min, and the flow rate of N2 gas to 179 ml / min.

[0190] After CVD treatment, the introduction of methane gas was stopped, and under conditions where the flow rate of N2 gas was adjusted to 224 ml / min, the temperature was maintained at 900°C for 30 minutes, then cooled, and carbon-coated alumina particles (A-2) were obtained.

[0191] <Preparation Example 3>

[0192] Mesoporous silica (SBA-15) was prepared by the sol-gel method. Specifically, it was prepared by the following method. First, using a 500 ml beaker, 15 g of surfactant (P-123) was dissolved in 360 ml of pure water, 33 g of tetraethoxysilane (TEOS) was added, and the mixture was stirred for 5 minutes. Subsequently, 60 ml of 36 mass% hydrochloric acid was added dropwise over 30 minutes, stirred at 35°C for 20 hours, and then stirred at 95°C for 24 hours. The resulting white precipitate was dried at 80°C for 12 hours, and then calcined under air at 550°C for 6 hours to obtain SBA-15.

[0193] Next, carbon-coated silica particles (A-3) were obtained by the same operation as in Example 1, except that mesoporous silica (SBA-15) was used instead of silica as the inorganic particle.

[0194] <Preparation Example 4>

[0195] Carbon-coated magnesium oxide particles (A-4) were obtained by the same operation as in Example 2, except that magnesium oxide was used instead of alumina as the inorganic particle.

[0196] <Preparation Example 5>

[0197] In order to increase the degree of crystal regularity and to form an oxide layer of Si and Al on the surface, Sendust was heated at 700°C for 5 hours under an Ar atmosphere, and then heated at 150°C for 5 hours in the atmosphere.

[0198] Next, carbon-coated Sendust particles (A-5) were obtained by the same operation as in Example 1, except that Sendust obtained instead of silica was used as the inorganic particle.

[0199] <Preparation Example 6>

[0200] In Example 2 of preparation, carbon-coated ferrite particles (A-6) were obtained by the same operation except that ferrite was used instead of alumina as the inorganic particle.

[0201] [Measurement and Evaluation of Carbon Composite Materials]

[0202] Measurement and evaluation of the following items were performed on the obtained carbon composite material. The results of these measurements and evaluations are summarized in Table 1.

[0203] <Specific Surface Area (BET Specific Surface Area)>

[0204] After vacuum heating and drying the obtained carbon composite material at 150°C for 6 hours, the specific surface area was determined using the multi-point method (5 points) from the nitrogen adsorption isotherm measured using the high-precision automatic gas / vapor adsorption amount measuring device “BEL SORP MAX” (manufactured by BEL JAPAN Inc.).

[0205] <Carbon Load (Carbon Content in Carbon Composite Material)>

[0206] The carbon loading of the obtained carbon composite material was measured using a differential thermal and thermogravimetric simultaneous measurement device “DTG-60 / 60H” (manufactured by Shimadzu Corporation). Specifically, while measuring the mass of the obtained carbon composite material, it was heated to 120°C at a rate of 10°C / min under synthetic air circulation (50cc / min) and maintained for 30 minutes, then heated to 800°C at a rate of 5°C / min and maintained for 1 hour, and then cooled to 120°C at a rate of -10°C / min and maintained for 30 minutes. The carbon loading per mass was calculated from the difference between the average mass when maintained at 120°C before heating to 800°C and the average mass when maintained at 120°C after heating to 800°C.

[0207] Average number of layers in graphene

[0208] From the specific surface area and carbon loading obtained by the above-described method, the average number of graphene layers was calculated using the following formula.

[0209] Average number of graphene layers = Carbon loading per area (g / m²) / (Mass of graphene per area [g / m²])

[0210] In addition, the "carbon loading per area (g / m²)" is a value obtained by dividing the carbon loading (g) of the carbon composite material per mass, calculated by the method described above, by the specific surface area (m² / g) of the inorganic particles possessed by the core-shell particles or the core-shell linkage.

[0211] <Carbon Content (Graphene Content)>

[0212] The carbon content in the carbon composite material was calculated using the following formula.

[0213] Carbon content (%) = Carbon face density of graphene (g / m²) × Specific surface area of ​​inorganic particles possessed by core-shell particles or core-shell links (m² / g) × Average number of graphene layers

[0214] In addition, the carbon plane density of graphene is 7.61 × 10⁻⁶ -4 It was set to g / ㎡.

[0215]

[0216] [Manufacturing of Electronic Interference Suppression Materials]

[0217] The details of each component listed in Table 2 used in the manufacture of the electronic interference suppression material are as follows.

[0218] [Organic matter]

[0219] · Epoxy resin: EPICLON N670; Cresol novolak-type epoxy resin; Manufactured by DIC Corporation, Epoxy equivalent: 210

[0220] ·Phenol resin: PC-25; Sumitomo Bakelite Co., Ltd.

[0221] · Curing agent: BRG-557; Phenol novolak resin; Manufactured by Aica Kogyo Company, Limited

[0222] · Curing Accelerator: CUREZOL C17Z; Imidazole compound; Agent of SHIKOKU CHEMICALS CORPORATION

[0223] · Flame Retardant: RABITLE (Phospazene-based flame retardant) FP100; Manufactured by Mitsui Fine Chemicals, Inc.

[0224] · Ethylene-ethyl acrylate copolymer: MB-870; Manufactured by Nippon Unicar Company Limited

[0225] · Lubricant: Stearic acid; Manufactured by NOF CORPORATION

[0226] [Inorganic]

[0227] · Silica: FB105; Manufactured by Denka Company Limited, Average particle diameter: 12㎛

[0228] · Alumina: DAW 07; Manufactured by Denka Company Limited, Average particle diameter: 8㎛, Maximum particle diameter: 50㎛

[0229] [Carbon Materials]

[0230] · Carbon Black (CB): TPK1227R; Manufactured by Cabot Corporation, Average particle diameter: 0.1㎛

[0231] · Carbon Nanotube (CNT): LUCAN; Manufactured by LG, Average fiber length: 30㎛, Average fiber diameter: 0.02㎛, Aspect ratio: 1500

[0232] 〔etc〕

[0233] · Fe-based alloy powder: Fe content? 95wt% (remainder Si, Cr), BET specific surface area: 5㎡ / g

[0234] <Examples 1–7 and Comparative Examples 1–3>

[0235] Each component of the type and amount listed in Table 2 was fed into a Henschel mixer and mixed, then fed into a twin-roll kneading device heated to 110°C, and heat kneading was performed until uniform. Subsequently, the obtained heat-kneaded material was fed into a cold roll, stretched into a sheet, and then ground to obtain an electron interference suppression material composition. The obtained electron interference suppression material composition was compression molded into a molded body with a thickness of 0.5 mm, 1.0 mm, or 25 mm (temperature: 175°C, pressure: 10 MPa) to obtain an electron interference suppression material.

[0236] <Examples 8–10>

[0237] Each component of the type and amount listed in Table 2 was extruded into a tube shape of 0.5 mm using an extruder heated to 180°C, rolled into a plate shape in a rolling mill, and an electron interference suppression material composition was obtained. The obtained electron interference suppression material composition was compression molded into a molded body with a thickness of 0.5 mm, 1.0 mm, or 25 mm (temperature: 190°C, pressure: 15 MPa), and an electron interference suppression material was obtained.

[0238] <Example 11>

[0239] 56 parts by mass of carbon-coated alumina particles (A-2) obtained in Preparation Example 2 were mixed with 104 parts by mass of a mixed solution containing phenol resin, methanol, and acetone (solid content concentration 43%), and then a sheet with a thickness of 0.15 mm was produced using the doctor blade method, and then the sheet was pressed in multiple layers and then heat-treated at 150°C for 2 hours to obtain a sheet sample (20 mm × 20 mm) with a thickness of 0.5 mm.

[0240] <Example 12>

[0241] In Example 11, a sheet sample was obtained by the same operation except that a sheet with a thickness of 0.15 mm was produced by the doctor blade method, the sheet was pressed in multiple layers, and then heat-treated at 150°C for 2 hours to obtain a sheet sample (20 mm × 20 mm) with a thickness of 0.9 mm.

[0242] <Comparative Example 4>

[0243] 70 parts by mass of Fe-based alloy powder and 150 parts by mass of a mixed solution containing phenol resin, methanol, and acetone (solid content 43%) were mixed, and then a sheet with a thickness of 0.15 mm was produced using the doctor blade method, and then the sheet was pressed in multiple layers, and then heat treated at 150°C for 2 hours to obtain a sheet sample (20 mm × 20 mm) with a thickness of 0.5 mm.

[0244]

[0245] [Measurement and Evaluation of Electron Interference Suppression Materials]

[0246] For the electromagnetic interference suppression materials obtained in Examples 1 to 10 and Comparative Examples 1 to 3, measurement evaluations were performed on thermal conductivity, coefficient of thermal expansion, volume resistance (volume resistivity), electromagnetic wave absorption performance (frequency 10 GHz, near-field measurement system), and electromagnetic wave absorption performance (frequency 5 GHz, far-field measurement system). The results of these measurement evaluations are summarized in Table 3.

[0247] For the sheet samples (electronic interference suppression materials) obtained in Examples 11 and 12 and Comparative Example 4, measurement evaluations of surface resistance, transmission attenuation power (Rtp), and voltage standing wave ratio (VSWR) were performed. The results of these measurement evaluations are summarized in Table 4.

[0248] Thermal conductivity

[0249] In the example, laser light was irradiated onto one side of an electronic interference suppression material, which is a molded body with a thickness of 1.0 mm, and thermal energy with periodically modulated intensity was applied. A temperature sensor was used to detect the phase difference of the temperature response on the other side of the molded body, the thermal diffusivity and specific heat were determined, and the thermal conductivity was calculated.

[0250] <Coefficient of Thermal Expansion>

[0251] Using the electron interference suppression material, which is a molded body with a thickness of 1.0 mm obtained in the example, the thermal analysis device “SSC / 5200” (manufactured by Seiko Instruments Inc.) was used by the TMA method, and the temperature was raised from room temperature (25°C) to 300°C at a heating rate of 5°C / min. From the obtained TMA chart, the slope of the part closest to a straight line between 25°C and 60°C was defined as the coefficient of thermal expansion.

[0252] Volume Resistance (Volume Resistivity)

[0253] Using the electronic interference suppression material, which is a molded body with a thickness of 1.0 mm obtained in the example, the volume resistivity at 150°C was measured in accordance with JIS K-6911:2006.

[0254] Electromagnetic wave absorption performance (frequency 10 GHz, near-field measurement system)

[0255] An electromagnetic interference suppression material formed to a thickness of 0.5 mm was installed between a high-frequency oscillation device and a receiving antenna, and the electromagnetic wave intensity when electromagnetic waves of a frequency of 10 GHz were generated was measured in the case with and without the molded body, and the ratio (electromagnetic wave intensity when electromagnetic waves are absorbed by the electromagnetic interference suppression material / electromagnetic wave intensity when there is no electromagnetic interference suppression material) was defined as the electromagnetic wave absorption performance in dB units.

[0256] In addition, electromagnetic field strength was measured in accordance with “Journal of the Institute of Electronics, Information and Communication Engineering B Vol.J97-B No.3 pp.279-285”.

[0257] Electromagnetic wave absorption performance (frequency 5GHz, far-field measuring system)

[0258] A copper plate (600 mm × 600 mm) with a thickness of 1 mm was installed on an anti-reflection radio wave absorber, and an electromagnetic interference suppression material (440 mm × 440 mm) formed to a thickness of 25 mm was installed on a metal plate. Subsequently, an antenna was mounted on a network analyzer via a cable, and electromagnetic waves of a frequency of 5 GHz were transmitted from one antenna and reflected by the electromagnetic interference suppression material or the radio wave absorber and the metal plate loaded underneath, and the electromagnetic wave intensity was measured by receiving them at the one antenna. In addition, electromagnetic waves were radiated in the same manner as above without installing the electromagnetic interference suppression material on the metal plate, and the electromagnetic wave intensity was measured. The ratio of these values ​​(electromagnetic wave intensity when absorbed by the electromagnetic interference suppression material / electromagnetic wave intensity when there is no electromagnetic interference suppression material) was referred to as electromagnetic wave absorption performance in dB units.

[0259] In addition, electromagnetic field intensity was measured in accordance with “Reports of Kagoshima Prefectural Institute of Industrial Technology No. 15 (2001), pp. 53-61”.

[0260] Surface Resistance

[0261] In accordance with JIS K-6911:2006, the surface resistance was measured by measuring the resistance meter probes at intervals of 1 cm.

[0262] <Transmission Decay Rate (Rtp) and Voltage Standing Wave Ratio (VSWR)>

[0263] In the measurement method of the IEC 62333-2 Transmission Attenuation Ratio, the Rtp and Voltage Standing Wave Ratio (VSWR) of the sheet sample in the frequency bands listed in Table 4 were measured in accordance with the said method, except that a coplanar line with a line width of 0.6 mm was used instead of the microstrip line used in the said method.

[0264]

[0265]

[0266] As shown in Table 3, the electromagnetic interference suppression materials of Examples 1 to 10 have good electromagnetic wave absorption performance. In addition, it can be said that they have good electromagnetic interference suppression performance in the near field due to having high volume resistivity. They also possess high thermal conductivity.

[0267] As shown in Table 4, the sheet samples of Examples 11 and 12 had small Rtp at 3 GHz, while Rtp at 30 GHz and 45 GHz each showed large values ​​exceeding 20 dB.

[0268] Meanwhile, the sheet sample of Comparative Example 4 showed a larger Rtp at 3 GHz compared to the sheet samples of Examples 11 and 12, and a smaller value at 45 GHz than the sheet samples of Examples 11 and 12.

[0269] Regarding the voltage standing wave ratio (VSWR), both samples were 1.5 or less, but the values ​​for the sheet samples of Examples 11 and 12 at 30 GHz and 5 GHz were 1.1, which is a very small value.

[0270] From the above results, it can be said that the sheet samples of Examples 11 and 12 have excellent frequency selectivity and exhibit a large electronic interference suppression effect in the high-frequency region of 30 GHz or higher without deterioration of VSWR.

[0271] Accordingly, the configuration of the present disclosure is an effective means for suppressing electronic interference occurring in the microwave band (3 GHz to 30 GHz) and high frequency regions exceeding 30 GHz, and can be said to be effective as a high-frequency noise suppression sheet used in a near-field environment such as inside a mobile phone.

Claims

Claim 1 An electron interference suppression material comprising a matrix material including organic and inorganic materials and a carbon composite material, wherein the organic material is a thermosetting resin and the content of the organic material is 0.1 to 40 mass%, and the carbon composite material is at least one selected from a core-shell particle having a coating layer of graphene having an average number of layers of 4 or less coated on the surface of an inorganic particle, and a core-shell connector having a coating layer of graphene having an average number of layers of 4 or less coated on the surface of a connector of inorganic particles, and the volume resistivity is 10 3 Electron interference suppression material having a value of Ω·cm or greater. Claim 2 An electronic interference suppression material according to claim 1, wherein the average particle diameter of the inorganic particles having the core-shell particles and the inorganic particles having the core-shell linkage is 100 μm or less. Claim 3 An electronic interference suppression material according to claim 1 or 2, wherein the graphene content in the electronic interference suppression material is 0.001 to 30 mass% with respect to the entire electronic interference suppression material. Claim 4 An electronic interference suppression material according to claim 1 or 2, wherein the inorganic particle having the core-shell particle and the inorganic particle having the core-shell linker comprise at least one selected from alumina, silica, magnesium oxide, tungsten carbide, and aluminum nitride. Claim 5 An electronic interference suppression material according to claim 1 or 2, wherein the inorganic particles having the core-shell particles and the inorganic particles having the core-shell linkage are magnetic materials. Claim 6 An electronic interference suppression material according to claim 5, wherein the magnetic body comprises at least one selected from magnetic metals, magnetic metal alloys, and magnetic oxides, and the magnetic oxide is at least one selected from ferrites and magnetites. Claim 7 In claim 6, the electronic interference suppression material wherein the magnetic metal has a flat shape. Claim 8 delete Claim 9 delete Claim 10 An electronic interference suppression material according to claim 1 or 2, wherein the inorganic material is ceramics.

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