TW201938662A - Electromagnetic absorber composition, three-dimensionally molded article formed from electromagnetic absorber, electronic component and electronic device using same, and methods for producing electronic component and electronic device - Google Patents

Abstract

This three-dimensionally molded article formed from an electromagnetic absorber is molded using an electromagnetic absorber composition containing a binder resin and iron oxide which is an electromagnetic wave absorbing material which magnetically resonates in millimeter-wave and higher frequency bands. The three-dimensionally molded article is molded into a thin-wall structure capable of covering an electronic member and satisfies the relational expression d * V1/3 > 0.4, where d (mm) represents the wall thickness of the three-dimensionally molded article, and V (%) represents the volume content percentage of the electromagnetic wave absorbing material contained in the three-dimensionally molded article. Moreover, the electromagnetic wave transmission attenuation in the millimeter-wave and higher frequency bands is 10dB or greater.

Description

Composition for electromagnetic wave absorber, three-dimensional shape of electromagnetic wave absorber, electronic component and electronic device using the same, and manufacturing method of electronic component and electronic device

The present invention relates to an electromagnetic wave absorber that absorbs electromagnetic waves in the millimeter wave band, and more specifically relates to a composition for an electromagnetic wave absorber, a three-dimensional shape of the electromagnetic wave absorber, electronic components and electronic devices using the same, and electronic components and electronic devices thereof. Production method.

With the development of wireless communication technology represented by mobile phones, various devices and sensors are wirelessly connected to the network. Moreover, in the medical field, from the viewpoint of preventing infection, devices are wirelessly connected, and medical devices are also being connected wirelessly. Such communications require high speed and large capacity over relatively short distances and high frequency of use. With the increase in the use of such high-frequency devices, malfunctions caused by noise from the devices, interference with the use of electromagnetic waves, and the like have increased the risk of malfunctions in electronic devices and communications. In recent years, millimeter-wave radios have also been installed for the purpose of preventing collision accidents in automobiles. In such medical and automotive fields, malfunctions of equipment cannot affect malfunctions because they affect human lives. Here, the electromagnetic wave absorber that is called EMC (Electromagnetic Compatibility) as a countermeasure to prevent the bad state caused by the noise and interference of the equipment is suitable for circuit components and transmission circuits that need to transmit and receive millimeter wave electromagnetic waves. Sexual improvement.

In order to suppress high-frequency noise, a conventional electromagnetic wave absorption sheet using magnetic loss of a magnetic material has a low effect, and a resonance type electromagnetic wave absorption sheet using a conductive material is necessary (Patent Document 1, Non-Patent Document 1). However, it is not suitable because a certain circuit element and a transmission path that are in direct contact with a conductive material to be turned on cause short circuits. In addition, even if the conductive layer of the resonance-type electromagnetic wave absorbing sheet is prevented from directly contacting the circuit element and the transmission path with an adhesive for attaching the circuit element and the transmission path, the sheet is cut / punched to a desired size. During use, the conductive layer will be exposed on the cut surface, and there is a danger of short-circuiting the circuit due to the contact of this part. In addition, the danger of short circuit caused by the fall of the conductive material cannot be wiped out.

On the other hand, iron oxide magnetic bodies are non-conductive materials, and there is no danger of short circuits. In recent years, it has been found that ε-type iron oxide has an electromagnetic wave absorption ability in the millimeter wave band, and the absorption frequency can be controlled by the substitution element and its substitution amount (Patent Documents 2 and 3). Further, it is known that hexagonal ferrite also has an electromagnetic wave absorption capability in the millimeter wave band (Patent Document 4). [Prior Art Literature] [Patent Literature]

[Patent Document 1] JP 2007-81119 (Patent No. 5481613) [Patent Document 2] JP 2008-60484 (Patent No. 4787978) [Patent Document 3] JP 2008-277726 (Patent No. 4798791) [Patent Document 4] JP 2007-250823 (Patent No. 4674380) [Non-Patent Document]

[Non-Patent Document 1] Research Report of Tokyo Metropolitan Industrial Technology Research Center, No. 9, 2014

[Problems to be solved by the invention]

In addition, when a sheet-shaped electromagnetic wave absorber is adhered to a noise generation source or a circuit element or a transmission path to be prevented from being affected by the noise with an adhesive or the like, generally, the shape of the electromagnetic wave absorber sheet is Since it is difficult to follow the shape of the surface of the circuit element or the conveyance path, the sheet may peel off. In addition, since the size of the circuit element or the transmission path is reduced, there is a problem that handling of the electromagnetic wave absorber sheet is difficult. Furthermore, because of the material and thickness of the surface of the circuit element, the inability to adhere to the adhesive or the contact of the adhesive will also have a bad effect on the circuit element or the transmission path.

In addition, the noise suppression effect is related to the presence of the electromagnetic wave absorbing material in the direction in which the electromagnetic wave progresses, and the more the electromagnetic wave absorbing material is present, the higher the noise suppression effect. Therefore, because of the thickness of the electromagnetic wave absorber and the uneven distribution of the electromagnetic wave absorbing material, the noise suppression effect will be reduced, and noise will leak.

In order to solve the foregoing problems, the present invention provides a three-dimensional shape of an electromagnetic wave absorber, which can prevent the electromagnetic wave absorber from leaking noise to the source of noise or to prevent circuit elements or transmission lines from preventing the influence of noise. The way of information installation. [Means to solve the problem]

The composition for an electromagnetic wave absorber of the present invention is a composition for an electromagnetic wave absorber used to form a three-dimensional shape of the electromagnetic wave absorber, and includes: an electromagnetic wave absorbing material and a binder resin; and the electromagnetic wave absorbing material is above the millimeter wave frequency band. Iron oxide that performs magnetic resonance in the frequency band; when the thickness of the three-dimensional shaped object of the electromagnetic wave absorber is d (mm), the volume fraction of the electromagnetic wave absorbing material in the composition for the electromagnetic wave absorber is V ( %), The relationship of d × V ^1/3 > 0.4 is established; the electromagnetic wave transmission attenuation in the frequency band above the millimeter wave band is 10 dB or more.

The three-dimensional shaped article of the electromagnetic wave absorber of the present invention is a three-dimensional shaped article of the electromagnetic wave absorber formed by using the composition for an electromagnetic wave absorber of the present invention, wherein the three-dimensional shaped article of the electromagnetic wave absorber is shaped to cover the electronic component. Thin structure; when the thickness of the three-dimensional shaped object of the electromagnetic wave absorber is d (mm), and the volume fraction of the electromagnetic wave absorbing material contained in the three-dimensional shaped object of the electromagnetic wave absorber is V (%), d × is established. The relational expression of V ^1/3 > 0.4 is that the electromagnetic wave transmission attenuation in a frequency band above the millimeter wave band is 10 dB or more.

The electronic component of the present invention includes an electronic member covered with the three-dimensional shaped object of the electromagnetic wave absorber of the present invention.

An electronic device of the present invention includes the electronic component of the present invention described above.

The method for manufacturing an electronic component of the present invention includes the process of preparing the above-mentioned composition for an electromagnetic wave absorber of the present invention; the process of using the aforementioned composition for an electromagnetic wave absorber to form a three-dimensional shape of the electromagnetic wave absorber; Preform, a process of bonding to an electronic component and covering it.

The method for manufacturing an electronic device according to the present invention includes a process of assembling an electronic component manufactured by the method for manufacturing an electronic component according to the present invention into an electronic device. [Effect of the invention]

According to the present invention, a non-conductive material iron oxide is used as an electromagnetic wave absorbing material to form a three-dimensional shape of an electromagnetic wave absorber having a thin structure, and the thickness of the three-dimensional shape of the electromagnetic wave absorber and the three-dimensional shape of the electromagnetic wave absorber are formed. The volume fraction of the above-mentioned electromagnetic wave absorbing material is controlled in a specific relationship, and it is possible to provide an electromagnetic wave absorber that does not cause a short circuit and has no noise leakage.

The composition for an electromagnetic wave absorber disclosed in the present case is a composition for an electromagnetic wave absorber used to form a three-dimensional shape of the electromagnetic wave absorber, and includes: an electromagnetic wave absorber and a binder resin; and the electromagnetic wave absorber is in a millimeter wave band or more. Iron oxide that performs magnetic resonance in the frequency band; when the thickness of the three-dimensional shaped object of the electromagnetic wave absorber is d (mm), the volume fraction of the electromagnetic wave absorbing material in the composition for the electromagnetic wave absorber is V ( %), The relationship of d × V ^1/3 > 0.4 is established; the electromagnetic wave transmission attenuation in the frequency band above the millimeter wave band is 10 dB or more.

Using the composition for an electromagnetic wave absorber, a three-dimensional electromagnetic wave absorber having a thin structure is formed. The thickness of the three-dimensional electromagnetic wave absorber and the volume of the electromagnetic wave absorber in the three-dimensional electromagnetic wave absorber are formed. The content ratio is controlled to the above-mentioned specific relationship, and an electromagnetic wave absorber can be provided which does not cause a short circuit and has no noise leakage.

The electromagnetic wave absorbing material is preferably a hexagonal ferrite containing at least one selected from the group consisting of Sr and Ba. Furthermore, the electromagnetic wave absorbing material is hexagonal ferrite containing Sr, and it is preferable that a part of Fe positions of the hexagonal ferrite containing Sr is replaced with Al. The hexagonal ferrite is a non-conductive iron oxide that undergoes magnetic resonance in a frequency band above the millimeter wave band. By replacing a part of the Fe position of the hexagonal ferrite containing Sr with Al, it is possible to carry electromagnetic waves. Changes in the absorbed magnetic resonance frequency can make thermal stability better.

The electromagnetic wave absorbing material is ε-type iron oxide, and a part of the Fe position of the ε-type iron oxide is preferably substituted with at least one selected from the group consisting of Al, Ga, and In. The ε-type iron oxide is a non-conductive iron oxide that undergoes magnetic resonance in a frequency band above the millimeter wave band, and a part of the Fe position is replaced with at least one selected from the group consisting of Al, Ga, and In. It is possible to change the magnetic resonance frequency that is responsible for electromagnetic wave absorption.

The binder resin preferably contains at least one selected from the group consisting of an active energy ray-curable resin, a thermosetting resin, a thermoplastic resin, and a rubbery resin. By using the above-mentioned binder resin, a three-dimensionally shaped electromagnetic wave absorber having a thin structure can be formed by various methods.

In addition, the three-dimensional shape of the electromagnetic wave absorber disclosed in the present case is a three-dimensional shape of the electromagnetic wave absorber formed by using the composition for the electromagnetic wave absorber disclosed above, wherein the three-dimensional shape of the electromagnetic wave absorber is formed to cover the electronic component. Thin structure; when the thickness of the three-dimensional shape of the electromagnetic wave absorber is d (mm) and the volume fraction of the electromagnetic wave absorbing material contained in the three-dimensional shape of the electromagnetic wave absorber is V (%), d × is established. The relational expression of V ^1/3 > 0.4 is that the electromagnetic wave transmission attenuation in a frequency band above the millimeter wave band is 10 dB or more.

Using the composition for an electromagnetic wave absorber, a three-dimensional electromagnetic wave absorber having a thin structure is formed. The thickness of the three-dimensional electromagnetic wave absorber and the volume of the electromagnetic wave absorber in the three-dimensional electromagnetic wave absorber are formed. The content ratio is controlled in the above-mentioned relationship, and even if the thickness of the three-dimensional shaped object of the electromagnetic wave absorber is changed during forming, it can ensure a certain electromagnetic wave absorption performance and provide an electromagnetic wave absorber without noise leakage.

The volume resistivity of the three-dimensional shaped object of the electromagnetic wave absorber is preferably 10 ¹⁰ Ωcm or more. This can reliably prevent the occurrence of a short circuit.

The electronic component disclosed in the present application is an electronic component including an electronic component covered with the three-dimensional shape of the electromagnetic wave absorber disclosed above. By covering the electronic component with the three-dimensional shaped object of the electromagnetic wave absorber, EMC (electromagnetic compatibility) of the electronic component can be ensured. In other words, regarding the above-mentioned electronic components, electromagnetic waves emitted from the electronic components do not affect any other devices or systems, and even if they receive electromagnetic waves from other devices or systems, they can ensure that the operation resistance is satisfied.

It is preferable that the three-dimensional shaped object of the electromagnetic wave absorber contacts and follows the surface of the electronic component. This makes it possible to more reliably prevent noise leakage and increase the EMC (electromagnetic compatibility) of electronic components.

The three-dimensional shaped object of the electromagnetic wave absorber may have a non-contact portion on a surface of the electronic component. This is because, depending on the surface shape of the electronic component, it may be difficult to form the three-dimensional shape of the electromagnetic wave absorber into a shape that contacts the surface of the electronic component.

Examples of the electronic component include a circuit element, a transmission path, and the like.

The electronic device disclosed in this application is an electronic device including the electronic components disclosed above. Because the electronic components are provided, it is possible to ensure EMC (electromagnetic compatibility) of electronic equipment.

The method for manufacturing an electronic component disclosed in the present application includes a process of preparing the composition for an electromagnetic wave absorber disclosed above; a process of using the composition for an electromagnetic wave absorber to form a three-dimensional shape of the electromagnetic wave absorber; and forming the electromagnetic wave absorber A three-dimensional object that is bonded to an electronic component and covered. According to the manufacturing method described above, an electronic component having high EMC (Electromagnetic Compatibility) can be manufactured.

The method for manufacturing an electronic device disclosed in this application includes a process of assembling an electronic component manufactured by the method for manufacturing an electronic component disclosed above into an electronic device. According to the manufacturing method described above, an electronic device with high EMC (Electromagnetic Compatibility) can be manufactured.

(Embodiment of composition for electromagnetic wave absorber) First, the embodiment of the composition for electromagnetic wave absorber will be described. The composition for an electromagnetic wave absorber according to this embodiment is used to form a three-dimensional shape of the electromagnetic wave absorber, and includes: an electromagnetic wave absorbing material and a binder resin; and the electromagnetic wave absorbing material is iron oxide that undergoes magnetic resonance in a frequency band above the millimeter wave band. When the thickness of the three-dimensional shaped object of the electromagnetic wave absorber is d (mm), and when the volume fraction of the electromagnetic wave absorbing material in the composition for the electromagnetic wave absorber is V (%), d × is established. The relational expression of V ^1/3 >0.4; the electromagnetic wave transmission attenuation in a frequency band above the millimeter wave band is 10 dB or more.

Hereinafter, each component contained in the said composition for electromagnetic wave absorbers is demonstrated.

<Electromagnetic Wave Absorbing Material> The electromagnetic wave absorbing material is an iron oxide that performs magnetic resonance in a frequency band above the millimeter wave band. Specifically, the following hexagonal ferrite or ε-type oxide can be used. The volume fraction of the electromagnetic wave absorbing material in the composition for the electromagnetic wave absorber is set to V (%), and when the thickness of the three-dimensional shaped object of the electromagnetic wave absorber is set to d (mm), it is adjusted to be d × V. The relation of ^1/3 > 0.4.

[Hexagonal Ferrite] As the hexagonal ferrite, a hexagonal ferrite containing at least one selected from the group consisting of Sr and Ba and having a part of Fe positions replaced with Al can be used. The hexagonal ferrite has a magnetoplumbite type crystal structure and is represented by a general formula: AFe ₁₂ O ₁₉ , where A in the general formula is at least one selected from the group consisting of Sr and Ba. The hexagonal ferrite described above can change a part of the Fe position with a trivalent Al metal element to change the magnetic resonance frequency that is responsible for electromagnetic wave absorption.

The hexagonal ferrite is disclosed in detail in the aforementioned Patent Document 4 (Japanese Patent Application Laid-Open No. 2007-250823).

[ε-type iron oxide] As the ε-type iron oxide, it is possible to use an ε-type iron oxide in which a part of Fe positions is replaced with at least one selected from the group consisting of Al, Ga, and In. The ε-type iron oxide has an ε-phase crystal structure and is represented by a general formula: ε-Fe ₂ O _3. By replacing a part of the Fe position with at least one selected from the group consisting of Al, Ga, and In, it is possible to make Changes in the magnetic resonance frequency that bears electromagnetic wave absorption.

The above-mentioned ε iron oxide is disclosed in detail in the aforementioned Patent Document 2 (Japanese Patent Application Laid-Open No. 2008-60484) and Patent Document 3 (Japanese Patent Application Laid-Open No. 2008-277726).

<Binder resin> The above binder resin is used to disperse and fix the electromagnetic wave absorbing material, and as a matrix material user when forming a three-dimensional shape of the electromagnetic wave absorber, specifically, active energy ray-curable resin and thermosetting resin can be used. And at least one selected from the group consisting of a thermoplastic resin and a rubbery resin.

[Active energy ray-curable resin] As the active energy ray-curable resin, for example, urethane acrylic, acrylic resin acrylic, epoxy acrylic, and the like can be used. When the active energy ray-curable resin is used as the binder resin, a three-dimensional shaped article of an electromagnetic wave absorber can be produced by a photoforming method using a three-dimensional printer.

More specifically, a polyfunctional ethylenically unsaturated monomer having more than two functional groups can be used. For example, a linear or branched alkylene glycol di (meth) acrylic acid having a carbon number of 10 to 25 can be used. Alkyl glycol tri (meth) acrylic acid [eg, tripropylene glycol di (meth) acrylic acid, 1,6-hexanediol di (meth) acrylic acid, neopentyl glycol di (meth) acrylic acid, 1,9 -Nonanediol di (meth) acrylic acid, 3-methyl-1,5-pentanediol di (meth) acrylic acid, 2-n-butyl-2-ethyl-1,3-propanediol di (methyl) Group) acrylic acid, pentaerythritol tri (meth) acrylic acid, etc.], alicyclic rings having 10 to 30 carbon atoms contain di (meth) acrylic acid [eg, dimethyloltricyclodecanediene (meth) acrylic acid, etc.] . These can be used alone or in combination of two or more.

[Thermosetting resin] As the thermosetting resin, for example, a phenol resin, a urea resin, a melamine resin, an epoxy resin, an unsaturated polyester resin, an alkyd resin, a silicone resin, and polyurethane can be used. When the thermosetting resin is used as the binder resin, a three-dimensional shaped article of an electromagnetic wave absorber can be produced by a heat compression molding method.

[Thermoplastic resin] As the above-mentioned thermoplastic resin, for example, polyethylene, polypropylene, polystyrene, ABS resin, methyl methacrylate resin, polyvinyl chloride, polyamine, polyterephthalic acid, polyparaphenylene can be used. When dicarboxylic acid, polycarbonate, or the like is used as the binder resin, when the thermoplastic resin is used, a three-dimensional shaped article of an electromagnetic wave absorber can be produced by an injection molding method.

[Rubber-like resin] As the above-mentioned rubber-like resin, for example, a urethane rubber, a silicone rubber, a fluororubber, or the like, which is a thermosetting elastomer, can be used. When the rubber-like resin is used as the binder resin, a three-dimensional shaped article of an electromagnetic wave absorber can be produced by a heat compression molding method.

<Photopolymerization initiator> (1) When the active energy ray-curable resin is used as the binder resin, a photopolymerization initiator is added to the composition for an electromagnetic wave absorber. The photopolymerization initiator is a monomer that initiates a polymerization reaction or a crosslinking reaction of an active energy ray, and because the composition for an electromagnetic wave absorber includes the photopolymerization initiator, for example, it can be irradiated by active energy ray. The above-mentioned composition for an electromagnetic wave absorber emitted using a three-dimensional printer is cured.

As the active energy ray irradiated to the photopolymerization initiator, for example, ultraviolet light, near-ultraviolet light, visible light, infrared light, and far-infrared light can be appropriately selected and used.

As a photopolymerization initiator, there is no particular limitation as long as it can start polymerization at a low energy, and benzoin compounds having a carbon number of 14 to 18 can be used [for example, benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin propyl ether. , Benzoin isobutyl ether, etc.], acetophenone compounds with 8 to 18 carbons [eg, acetophenone, 2,2-diethoxy-2-phenylacetophenone, 2,2-diethoxy 2-phenylacetophenone, 1,1-dichloroacetophenone, 2-hydroxy-2-methyl-phenylacetylene-1-one, diethoxyacetophenone, 1-hydroxycyclohexylbenzene Ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinylacetylene-1-one, etc.], anthraquinone compounds having 14 to 19 carbons [for example, 2-ethyl Anthraquinone, 2-t-butylanthraquinone, 2-chloroanthraquinone, 2-pentylanthraquinone, etc.], thioxanthone compounds having 13 to 17 carbons [for example, 2,4-diethylthioxanthine Ketone, 2-isopropylthioxanthone, 2-chlorothioxanthone, etc.], ketal compounds with 16 to 17 carbons [eg, acetophenone dimethyl ketal, benzyl dimethyl ketal, etc.] 13-21 carbon benzophenone compounds [for example, benzophenone, 4-benzidine-4'-methyldiphenylsulfide, 4,4'-bismethylaminobenzophenone Etc.], fluorenylphosphine oxide compounds having 22 to 28 carbon atoms [for example, 2,4,6-trimethylbenzylidene-diphenyl-phosphine oxide, bis- (2,6-dimethoxy Benzylfluorenyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzylidene) -phenylphosphine oxide, etc.], mixtures of compounds thereof, and the like. These can be used alone or in combination of two or more.

The amount of the photopolymerization initiator to be added may be 3.0 to 15 parts by mass when the total mass of the composition for an electromagnetic wave absorber is 100 parts by mass. When the above-mentioned photopolymerization initiator is used in combination of two or more kinds, the above-mentioned addition amount is determined as the total of the addition amounts of the respective photopolymerization initiators.

<Surface modifier> (1) When the active energy ray-curable resin is used as the binder resin, a surface modifier is added to the composition for an electromagnetic wave absorber. Thereby, the surface tension of the said composition for electromagnetic wave absorbers can be adjusted to a suitable range. By adjusting the surface tension of the composition for an electromagnetic wave absorber to an appropriate range, it is possible to obtain a light shaped product with good size accuracy. In order to obtain this effect, when the total amount of the surface modifier is set to 100 parts by mass of the composition for the electromagnetic wave absorber, the amount may be 0.005 to 3.0 parts by mass.

As the surface conditioner, a silicone compound or the like can be used. As the silicone compound, for example, a silicone compound having a polydimethylsiloxane structure can be used. Specifically, it can be polyether-modified polydimethylsiloxane, polyester fiber-modified polydimethylsiloxane, polyaralkyl-modified polydimethylsiloxane, or the like. More specifically, as the product name, YK-300, BYK-302, BYK-306, BYK-307, BYK-310, BYK-315, BYK-320, BYK-322, BYK-323 manufactured by BYK can be used. , BYK-325, BYK-330, BYK-331, BYK-333, BYK-337, BYK-344, BYK-370, BYK-375, BYK-377, BYK-UV3500, BYK-UV3510, BYK-UV3570; Evonik・ TEGO-Rad2100, TEGO-Rad2200N, TEGO-Rad2250, TEGO-Rad2300, TEGO-Rad2500, TEGO-Rad2600, TEGO-Rad2700 manufactured by Japan; GLANOL 100, GLANOL 115, GLANOL 400, GLANOL manufactured by Kyoeisha Chemical Co., Ltd. 410, GLANOL 435, GLANOL 440, GLANOL 450, B-1484, POLYFLOW ATF-2, KL-600, UCR-L72, UCR-L93, etc. These can be used alone or in combination of two or more. When the above-mentioned surface adjustment is used in combination of two or more types, the above-mentioned addition amount is determined as the total of the addition amounts of the respective surface modifiers.

The above-mentioned filler and dispersant can be further added to the composition for an electromagnetic wave absorber.

<Filler> 添加 By adding the filler described above, the electromagnetic wave absorption characteristics of the electromagnetic wave absorber can be improved. As the filler, for example, metal particles, metal fibers, carbon, carbon nanotubes, carbon nanotubes, etc., whose surface is covered with an insulator layer can be used.

<Dispersant> 添加 By adding the dispersant described above, the aforementioned electromagnetic wave absorbing material can be uniformly arranged without uneven distribution in the electromagnetic wave absorber, and the electromagnetic wave absorption characteristics of the electromagnetic wave absorber are improved. As the dispersant, a polymer dispersant having an Mw of 1,000 or more is preferably used. As the above polymer dispersant, as the trade name, DISPERBYK-101, DISPERBYK-102, etc. manufactured by BYK-Chemie; EFKA4010, EFKA4046, etc. manufactured by EFKA; DISPERSANT 6, DISPERSANT 8, etc. manufactured by SAN NOPCO; Noveon Various SOLSPERSE dispersants such as SOLSPERSE 3000, 5000 manufactured by the company; Adeka PulllonicL 31, F38, etc. manufactured by ADEKA; IONET S-20 by Sanyo Chemical Industry Co .; These can be used alone or in combination of two or more.

The addition amount of the dispersant may be 0.05 to 15 parts by mass when the total mass of the composition for an electromagnetic wave absorber is 100 parts by mass. When the dispersant is used in combination of two or more kinds, the above-mentioned added amount is determined as the total of the added amounts of the respective dispersants.

The composition for an electromagnetic wave absorber can be produced by uniformly dispersing and mixing the above components. By uniformly dispersing the above components, the uneven distribution of the electromagnetic wave absorbing material can be prevented, and an electromagnetic wave absorber without noise leakage can be produced. The above-mentioned mixing method is not particularly limited, and for example, a mixing method using a kneader, an extruder, a roll mill, or the like is preferred.

(Embodiment of Three-dimensional Shape of Electromagnetic Wave Absorber) Next, an embodiment of the three-dimensional shape of electromagnetic wave absorber will be described. The three-dimensional shape of the electromagnetic wave absorber of this embodiment is a three-dimensional shape of the electromagnetic wave absorber made of the composition for an electromagnetic wave absorber disclosed in the foregoing embodiment. The three-dimensional shape of the electromagnetic wave absorber is formed into a thin structure that can cover an electronic component. When the thickness of the three-dimensional shaped object is d (mm), and the volume fraction of the electromagnetic wave absorbing material included in the three-dimensional shaped object of the electromagnetic wave absorber is set to V (%), d × V ^1/3 > 0.4 is established. The relational expression is that the electromagnetic wave transmission attenuation in a frequency band above the millimeter wave band is 10 dB or more.

When forming a three-dimensional electromagnetic wave absorber using the composition for an electromagnetic wave absorber, it is always difficult to make the thickness of the three-dimensional electromagnetic wave absorber completely uniform. Therefore, the thickness of the three-dimensional shaped object of the electromagnetic wave absorber may vary. That is, there may be cases where a thin portion and a thick portion are generated in the three-dimensional shaped object of the electromagnetic wave absorber. At this time, the content of the electromagnetic wave absorbing material included in the thin portion is smaller than the content of the electromagnetic wave absorbing material included in the thick portion, and the electromagnetic wave absorption characteristics of the thin portion are reduced. That is, when the electromagnetic wave passes through the thin portion, the thickness through which the electromagnetic wave passes becomes thin, and the electromagnetic wave absorption effect decreases. As a result, unnecessary electromagnetic waves may leak from the inside of the device to the outside, which may cause a bad influence on the external device.

In contrast, when the thickness of the three-dimensional shaped article of the electromagnetic wave absorber is d (mm), and the volume fraction of the electromagnetic wave absorbing material contained in the three-dimensional shaped article of the electromagnetic wave absorber is V (%), d × is established. The relational expression of V ^1/3 > 0.4, even if the thickness of the three-dimensional shaped object of the electromagnetic wave absorber is changed during shaping, the electromagnetic wave absorption performance can be ensured over a certain area in the entire area of the three-dimensional shaped object of the electromagnetic wave absorber, and noise can be realized. It leaks small electromagnetic wave absorbers. Specifically, an electromagnetic wave absorber capable of securing an electromagnetic wave transmission attenuation greater than -10 dB can be realized. If the electromagnetic wave transmission attenuation is smaller than -10dB, the electromagnetic wave transmission attenuation is small, and there is a high risk of affecting the surrounding electronic equipment. The above-mentioned relational expressions have been made by the inventors through experiments. For example, when the thickness d is constant, it means that the volumetric content ratio V is set to be a certain value or more. When the volumetric content ratio V is set to be a constant value, This means that the thickness d is set to a certain value or more.

Moreover, the three-dimensional shaped object of the electromagnetic wave absorber can be formed beforehand in accordance with the surface shape of various electronic components or the frame of the electronic component, and the three-dimensional shaped object of the electromagnetic wave absorber can also be mounted on the electronic component as an electromagnetic wave absorber.

The volume resistivity of the three-dimensional electromagnetic wave absorber can be set to 10 ¹⁰ Ωcm by forming the three-dimensional electromagnetic wave absorber using the composition for the electromagnetic wave absorber containing a non-conductive iron oxide and a binder resin. the above. Thereby, the three-dimensional shaped object of the electromagnetic wave absorber can be used as a non-conductive material, and the occurrence of a short circuit can be reliably prevented.

Although the manufacturing method of the said three-dimensional electromagnetic wave absorber is not specifically limited, It can select from various manufacturing methods according to the kind of the binder resin used for the said composition for electromagnetic wave absorbers. For example, when producing a three-dimensional shaped article of an electromagnetic wave absorber by a photoforming method, an active energy ray-curable resin, a photopolymerization initiator, a surface conditioner, or a suitable combination of a filler and a dispersant may be used as necessary. At this time, the inkjet light forming method (MJM forming method) using an inkjet printer as the three-dimensional printer can easily and easily form the three-dimensional shaped object of the electromagnetic wave absorber with high forming accuracy. At this time, it is necessary to adjust the viscosity of the composition for an electromagnetic wave absorber to a proper viscosity for discharge from an inkjet printer.

When the thermosetting resin and the rubber-like resin are used as the binder resin, a three-dimensional shaped article of an electromagnetic wave absorber can be produced by a heat compression molding method. When the thermoplastic resin resin is used as the binder resin, a three-dimensional shaped article of an electromagnetic wave absorber can be produced by an injection molding method.

Next, an embodiment of the three-dimensional shaped object of the electromagnetic wave absorber will be described based on the drawings. FIGS. 1A and B and FIGS. 2A and B are schematic cross-sectional views showing a specific example of a three-dimensional shaped object of an electromagnetic wave absorber of this embodiment manufactured in accordance with the surface shape of a specific electronic component. Although the method for manufacturing the electromagnetic wave absorber three-dimensionally shaped product is not particularly limited, it can be applied to the bonding of the composition for the electromagnetic wave absorber from the light shaping method, the heat compression molding method, and the injection molding method using three-dimensional printing. The type of resin resin is selected.

The three-dimensional shaped objects 11 and 12 of the electromagnetic wave absorber shown in FIGS. 1A and 1B have a thin structure and are formed in a cup shape so as to cover an electronic component. The thicknesses d of the three-dimensional shaped objects 11 and 12 of the electromagnetic wave absorber shown in FIGS. 1A and 1B are formed substantially uniformly.

On the other hand, although the electromagnetic wave absorber three-dimensional shapes 21 and 22 shown in FIGS. 2A and B have a thin structure and are formed in a cup shape so as to cover electronic components, the electromagnetic wave absorber three-dimensional shapes 21 and 22 have thick portions, respectively. 21a, 22a and thin portions 21b, 22b.

The thickness d (mm) of the three-dimensional shaped objects 11, 12, 21, and 22 of the electromagnetic wave absorber shown in FIGS. 1A, B, and 2A, and B, and the electromagnetic wave absorption contained in the three-dimensional shaped objects 11, 12, 21, and 22 of the electromagnetic wave absorber The relationship between d × V ^{1/3 and} 0.4 is established between the volume fraction V (%) of the material. Even if the thickness changes during forming as shown in FIGS. 2A and B, the three-dimensional shaped object of the electromagnetic wave absorber can be formed. The electromagnetic wave absorption performance of the electromagnetic wave transmission attenuation in the frequency band above the millimeter wave band is 10 dB or more in the entire area, and it can be used as an electromagnetic wave absorber without noise leakage.

(Embodiments of electronic components and electronic devices) Next, embodiments of electronic components will be described. The electronic component of this embodiment includes an electronic member covered with a three-dimensional shaped object of the electromagnetic wave absorber disclosed in the foregoing embodiment. The electronic device of this embodiment includes the electronic component of this embodiment.

Since the electronic component constituting the electronic component is covered with the three-dimensional shaped object of the electromagnetic wave absorber, EMC (electromagnetic compatibility) of the electronic component can be ensured. In addition, since the electronic device includes the electronic component that secures EMC, EMC can be secured as the entire electronic device.

Examples of the electronic component covered with the three-dimensional shaped object of the electromagnetic wave absorber include a circuit element, a transmission path, and the like. Examples of the circuit element include a transistor, a diode, a resistor, a capacitor, an inductor, and a battery. Examples of the transmission path include wiring, a printed circuit board, a connector, and a socket. In addition, as the electronic component, for example, there is a circuit board including a circuit element, a transmission path, and the like.

Examples of the electronic device include a communication device using a wireless communication technology, a sensor, a medical device, and a millimeter wave radio.

Next, an embodiment of the electronic component will be described based on the drawings. 3A and 3B and FIGS. 4A and 4B are schematic cross-sectional views showing a part of an electronic component (for example, a circuit board) according to this embodiment including a circuit element covered with a three-dimensional shaped object of an electromagnetic wave absorber. FIG. 3A shows a part of an electronic component in which the circuit element 13 is covered with the three-dimensional shaped article 11 of the electromagnetic wave absorber shown in FIG. 1A. FIG. 3B shows a part of the electronic component in which the circuit element 14 is covered with the three-dimensional shaped object 12 of the electromagnetic wave absorber shown in FIG. 1B. FIG. 4A illustrates a part of an electronic component in which the circuit element 23 is covered with the three-dimensional shaped object 21 of the electromagnetic wave absorber shown in FIG. 2A. FIG. 4B shows a part of the electronic component in which the circuit element 24 is covered with the three-dimensional shaped object 22 of the electromagnetic wave absorber shown in FIG. 2B. More specifically, FIG. 3 and FIG. 4 show a part of a circuit board, for example.

In FIGS. 3A and 4A, the three-dimensional shapes 11 and 21 of the electromagnetic wave absorber contact and follow the surfaces of the circuit elements 13 and 23. On the other hand, in FIGS. 3B and 4B, the surfaces of the three-dimensional shaped objects 12 and 22 of the electromagnetic wave absorber have non-contact portions with respect to the circuit elements 14 and 24, respectively.

Next, an embodiment of a method for manufacturing an electronic component will be described. The method for manufacturing an electronic component according to this embodiment includes the steps of preparing a composition for an electromagnetic wave absorber disclosed in the foregoing embodiment; using the composition for an electromagnetic wave absorber to form a three-dimensional shape of the electromagnetic wave absorber; and absorbing the electromagnetic wave. A three-dimensional object that is bonded to an electronic component and covered. According to the manufacturing method described above, an electronic component having high EMC (Electromagnetic Compatibility) can be manufactured. Furthermore, in the above manufacturing method, since the three-dimensional shaped article of the electromagnetic wave absorber can be manufactured by a process different from that of the electronic component, the influence of heat and pressure when manufacturing the three-dimensional shaped article of the electromagnetic wave absorber is not less than that of the electronic component. Furthermore, because the three-dimensional shaped article of the electromagnetic wave absorber does not include a conductive layer and has a volume resistance of 10 ¹⁰ Ω ･ cm or more, there is no risk of a short circuit when contacting a circuit element or an electronic component.

Next, an embodiment of a method for manufacturing an electronic device will be described. The method for manufacturing an electronic device according to this embodiment includes a process of assembling an electronic component manufactured by the method for manufacturing an electronic component disclosed in the above embodiment into an electronic device. According to the manufacturing method described above, an electronic device with high EMC (Electromagnetic Compatibility) can be manufactured. [Example]

Hereinafter, the present invention will be described in detail based on examples. However, the present invention is not limited to the following examples.

(Example 1) <Production of composition for electromagnetic wave absorber> The following ingredients were kneaded with a pressurized batch kneader to produce a hexagonal ferrite magnetic powder, which is an electromagnetic wave absorbing material, and the volume fraction V became 51%. Composition A for an electromagnetic wave absorber of this embodiment. The hexagonal ferrite magnetic powder of the following composition formula is a one in which the magnetic resonance frequency of electromagnetic wave absorption is adjusted to 76G (Hz). (1) Hexagonal ferrite magnetic powder (composition formula: SrFe _10.56 Al _1.44 O ₁₉ ) (2) Silicone rubber (made by Shin-Etsu Chemical Co., Ltd., trade name "KE-541-U")

<Production of Three-Dimensional Shaped Electromagnetic Wave Absorber> Using the composition A for an electromagnetic wave absorber produced as described above, a thermal compression molding method using a hydraulic press at a temperature of 165 ° C was used to produce a length: 12 cm, a width: 12 cm, and a thickness. d: 2 mm sheet-shaped electromagnetic wave absorber three-dimensional shape (electromagnetic wave absorber). The value of d × V ^1/3 of the electromagnetic wave absorber of this embodiment is 1.60.

(Example 2) <Production of composition for electromagnetic wave absorber> The following ingredients were kneaded with a pressurized batch type kneader to produce an electromagnetic wave absorbing material, that is, ε-type iron oxide magnetic powder having a volume fraction V of 40%. Composition B for an electromagnetic wave absorber of this embodiment. The ε-type ferromagnetic powder of the following composition formula is a one in which the magnetic resonance frequency of the electromagnetic wave absorption is adjusted to 76 G (Hz). (1) ε-type iron oxide magnetic powder (composition formula: ε-Ga _0.46 Fe _1.54 O ₃ ) (2) Silicone rubber (made by Shin-Etsu Chemical Co., Ltd., trade name "KE-541-U")

<Production of Three-Dimensional Shaped Electromagnetic Wave Absorber> Using the composition B for an electromagnetic wave absorber produced as described above, a thermal compression molding method using a hydraulic press at a temperature of 165 ° C was used to produce a length: 12 cm, a width: 12 cm, and a thickness. d: 2 mm sheet-shaped electromagnetic wave absorber three-dimensional shape (electromagnetic wave absorber). The value of d × V ^1/3 of the electromagnetic wave absorber of this embodiment is 1.47.

(Example 3) <Preparation of composition for electromagnetic wave absorber> The following ingredients were kneaded with a heating extruder to produce a hexagonal ferrite magnetic powder, which is an electromagnetic wave absorbing material, and the volume fraction V was 47%. Composition C for an example of an electromagnetic wave absorber. The hexagonal ferrite magnetic powder described below is the same as the user in Example 1. (1) Hexagonal ferrite magnetic powder (composition formula: SrFe _10.56 Al _1.44 O ₁₉ ) (2) Polycarbonate (made by Teijin Co., Ltd., trade name "Panlite")

<Production of three-dimensional shaped article of electromagnetic wave absorber> Using the composition C for an electromagnetic wave absorber produced as described above, a three-dimensional shaped article of electromagnetic wave absorber having a length of 12 cm, a width of 12 cm, and a thickness d of 1 mm was produced by injection molding. (Electromagnetic wave absorber). The value of d × V ^1/3 of the electromagnetic wave absorber of this embodiment is 0.78.

Comparative Example 1 A three-dimensional electromagnetic wave absorber was produced in the same manner as in Example 1 except that the thickness d of the three-dimensional electromagnetic wave absorber (electromagnetic wave absorber) was changed to 0.5 mm. The value of d × V ^{1/3 in} this comparative example is 0.40.

(Comparative Example 2) A three-dimensional electromagnetic wave absorber (electromagnetic wave absorber) was produced in the same manner as in Example 2 except that the thickness d of the three-dimensional electromagnetic wave absorber was changed to 0.5 mm. The value of d × V ^{1/3 in} this comparative example is 0.37.

Comparative Example 3 A three-dimensional electromagnetic wave absorber (electromagnetic wave absorber) was produced in the same manner as in Example 3, except that the thickness d of the three-dimensional electromagnetic wave absorber was changed to 0.5 mm. The value of d × V ^{1/3 in} this comparative example is 0.39.

Next, the amount of electromagnetic wave transmission attenuation of the three-dimensional shaped object (electromagnetic wave absorber) of the electromagnetic wave absorber produced in Examples 1 to 3 and Comparative Examples 1 to 3 was measured by a free space method. Specifically, using a millimeter-wave network analyzer "ME7838A" (product name) manufactured by Anritsu Corporation, an electromagnetic wave absorber is irradiated with an input wave (millimeter wave) of a predetermined frequency from a transmitting antenna through a dielectric lens to be disposed in The receiving antenna on the back side of the electromagnetic wave absorber measures transmitted electromagnetic waves. The intensity of the irradiated electromagnetic wave and the intensity of the transmitted electromagnetic wave were grasped as voltage values, and the amount of electromagnetic wave transmission attenuation was obtained from the difference in intensity in dB units.

As a result, the amount of electromagnetic wave attenuation at 76 GHz is shown in Table 1 and FIG. 5. In Table 1, in addition to the amount of electromagnetic wave transmission attenuation, the types of the electromagnetic wave absorbing material and the binder resin, the thickness d of the electromagnetic wave absorber, and the values of the volume content V and d × V ^1/3 of the electromagnetic wave absorbing material are also recorded. 6 shows the electromagnetic wave absorption spectra of Example 1 and Comparative Example 3.

As can be understood from Table 1 and FIG. 5, the electromagnetic wave transmission attenuation of Examples 1 to 3 with a value of d × V ^1/3 exceeding 0.4 is higher than 10 dB, and the electromagnetic waves from the covered electronic components will not affect the electrons outside the covered. The component affects, and the electromagnetic wave from the electronic component outside the cover will not invade and affect the covered electronic component. In contrast, the electromagnetic wave transmission attenuation of Comparative Examples 1 to 3 with a value of d × V ^1/3 of 0.4 or less is less than 9 dB. The electromagnetic waves from the covered electronic components will affect the electronic components outside the coating. Electromagnetic waves from the electronic components outside the cover can invade and affect the covered electronic components. This should be because d × V ^1/3 exceeds 0.4. Even if the thickness of the electromagnetic wave absorber is changed, the amount of electromagnetic wave absorbing material in the electromagnetic wave absorber can be ensured to be more than a certain value, and the electromagnetic wave transmission attenuation amount can be achieved. [Industrial availability]

The composition for electromagnetic wave absorber and three-dimensional optical shape of electromagnetic wave absorber disclosed in this case can absorb electromagnetic waves in the high frequency band above the millimeter wave band, no noise leakage, and non-conductive electromagnetic wave absorber. Electronic components and electronic machines are useful.

11, 12, 21, 22‧‧‧Three-dimensional shape of electromagnetic wave absorber

21a, 22a‧‧‧thick part

21a, 22a‧‧‧Thin part

13, 14, 23, 24‧‧‧Circuit components

[FIG. 1] FIG. 1 is a schematic cross-sectional view showing an example of a three-dimensional shaped object of an electromagnetic wave absorber according to this embodiment. [FIG. 2] FIG. 2 is a schematic cross-sectional view showing another example of a three-dimensional shaped object of an electromagnetic wave absorber according to this embodiment. [FIG. 3] FIG. 3 is a schematic cross-sectional view showing an example of a part of the electronic component according to this embodiment. [FIG. 4] FIG. 4 is a schematic cross-sectional view showing another example of a part of the electronic component according to this embodiment. [FIG. 5] FIG. 5 is a graph showing an electromagnetic wave transmission attenuation amount at a frequency of 76 GHz of the electromagnetic wave absorber of the example and the comparative example. [FIG. 6] FIG. 6 is a diagram showing electromagnetic wave absorption spectra of the electromagnetic wave absorbers of Example 1 and Comparative Example 3. FIG.

Claims (14)

A composition for an electromagnetic wave absorber is a composition for an electromagnetic wave absorber used to form a three-dimensional shape of the electromagnetic wave absorber, and includes: an electromagnetic wave absorber and a binder resin; the electromagnetic wave absorber is performed in a frequency band above the millimeter wave band Iron oxide of magnetic resonance; When the thickness of the three-dimensional shaped object of the electromagnetic wave absorber is d (mm), the volume fraction of the electromagnetic wave absorbing material in the composition for the electromagnetic wave absorber is V (%) At the time, a relational expression of d × V ^1/3 > 0.4 is established; the electromagnetic wave transmission attenuation in a frequency band above the millimeter wave frequency band is 10 dB or more. The composition for an electromagnetic wave absorber according to claim 1, wherein the electromagnetic wave absorbing material is a hexagonal ferrite containing at least one selected from the group consisting of Sr and Ba. The composition for an electromagnetic wave absorber according to claim 1 or 2, wherein the electromagnetic wave absorbing material is hexagonal ferrite containing Sr; A part of Fe positions of the hexagonal ferrite containing Sr is replaced with Al. The composition for an electromagnetic wave absorber according to claim 1, wherein the electromagnetic wave absorbing material is an ε-type iron oxide; 的 A part of Fe positions of the ε-type iron oxide is at least 1 selected from the group consisting of Al, Ga, and In. Kind of replacement. The composition for an electromagnetic wave absorber according to any one of claims 1 to 4, wherein the aforementioned binder resin is selected from the group consisting of an active energy ray-curable resin, a thermosetting resin, a thermoplastic resin, and a rubbery resin. At least 1 species. A three-dimensional shaped object of an electromagnetic wave absorber, which is a three-dimensional shaped object of an electromagnetic wave absorber formed by using the composition for an electromagnetic wave absorber described in any one of claims 1 to 5, wherein the three-dimensional shaped object of the electromagnetic wave absorber is formed. The thin structure of the electronic component can be covered. The thickness of the three-dimensional shaped article of the electromagnetic wave absorber is d (mm), and the volume fraction of the electromagnetic wave absorbing material contained in the three-dimensional shaped article of the electromagnetic wave absorber is V (%). ), A relational expression of d × V ^1/3 > 0.4 is established, and the electromagnetic wave transmission attenuation in a frequency band above the millimeter wave band is 10 dB or more. The three-dimensional shaped article of an electromagnetic wave absorber according to claim 6, wherein the volume resistivity is 10 ¹⁰ Ωcm or more. An electronic component comprising an electronic component covered with a three-dimensional shaped object of an electromagnetic wave absorber according to claim 6 or 7. The electronic component according to claim 8, wherein the three-dimensional shaped object of the electromagnetic wave absorber contacts and follows the surface of the electronic component. The electronic component according to claim 8, wherein the three-dimensional shaped article of the electromagnetic wave absorber has a non-contact portion with respect to a surface of the electronic component. The electronic component according to any one of claims 8 to 10, wherein the electronic component includes a circuit element and a transmission path. An electronic device including the electronic component according to claim 11. An electronic component manufacturing method, comprising: a process of preparing the composition for an electromagnetic wave absorber according to any one of claims 1 to 5; (i) a process of forming a three-dimensional shape of the electromagnetic wave absorber using the aforementioned composition for an absorber; (ii) A process in which the three-dimensional shaped object of the electromagnetic wave absorber is bonded to an electronic component and covered. An electronic device manufacturing method includes a process of assembling an electronic component manufactured by the electronic component manufacturing method according to claim 13 into an electronic device.