JP2006332693A - Composite magnetic body and electromagnetic interference suppressor using the same - Google Patents
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本発明は、有機結合剤中に軟磁性体粉末を混練・分散させた複合磁性体とそれを用いた電磁干渉抑制体に関し、詳しくは、高周波電子回路/装置において問題となる電磁干渉の抑制に有効な複素透磁率特性の優れた複合磁性体と、その製造方法及びそれを用いた電磁干渉抑制体に関する。 The present invention relates to a composite magnetic material in which soft magnetic powder is kneaded and dispersed in an organic binder and an electromagnetic interference suppressor using the same, and more particularly to suppression of electromagnetic interference which is a problem in high-frequency electronic circuits / devices. The present invention relates to a composite magnetic body excellent in effective complex permeability characteristics, a manufacturing method thereof, and an electromagnetic interference suppressor using the same.
近年、デジタル電子機器をはじめ高周波を利用する電子機器類の普及が進み、中でも準マイクロ波帯域を使用する通信機器類の普及がめざましい。携帯電話に代表される移動体通信機器は、小型化軽量化の要求が顕著であり、高密度実装化が重要な技術課題の一つとなっている。したがって、過密に実装された電子部品類やプリント配線、あるいは、モジュール間配線等が互いに極めて接近することになり、更には、信号処理速度の高速化も図られているため、静電および電磁結合による線間結合の増大化や放射ノイズによる干渉などが生じ機器の正常な動作を妨げる事態が少なからず生じている。このような電磁障害に対して、従来は、主に導体シールドを施すことによる対策がなされてきた。 In recent years, electronic devices using high frequencies such as digital electronic devices have been widely used. In particular, communication devices using a quasi-microwave band have been widely used. Mobile communication devices represented by mobile phones are remarkably demanded for miniaturization and weight reduction, and high-density mounting is one of the important technical issues. Therefore, electronic components and printed wiring that are mounted densely, wiring between modules, etc. will be very close to each other, and further, signal processing speed is increased, so electrostatic and electromagnetic coupling There are not a few cases where the inter-line coupling is increased due to the noise and interference due to radiation noise occurs, thereby preventing the normal operation of the device. Conventionally, measures against such electromagnetic interference have been made mainly by providing a conductor shield.
しかしながら、導体シールドは空間とのインピーダンス不整合に起因する電磁波の反射を利用する電磁障害対策であるために、遮蔽効果は得られても不要輻射源からの反射による電磁結合が助長され、その結果、二次的な電磁障害を引き起こす場合が少なからず生じている。この二次的な電磁障害対策として、磁性体の磁気損失を利用した不要輻射の抑制が有効である。即ち、前記シールド体と不要輻射源の間に磁気損失の大きい磁性体を配設することで不要輻射を抑制することができる。 However, since the conductor shield is a countermeasure against electromagnetic interference that uses reflection of electromagnetic waves due to impedance mismatch with the space, even if the shielding effect is obtained, electromagnetic coupling due to reflection from unwanted radiation sources is promoted, and as a result In many cases, secondary electromagnetic interference is caused. As a secondary countermeasure against electromagnetic interference, it is effective to suppress unnecessary radiation using magnetic loss of a magnetic material. That is, unnecessary radiation can be suppressed by disposing a magnetic body having a large magnetic loss between the shield body and the unnecessary radiation source.
ここで、磁性体の厚さdは、μ″>μ′なる関係を満足する周波数帯域にてμ″に反比例するので、前記した電子機器の小型化及び軽量化要求に迎合する薄い電磁干渉抑制体、即ち、シールド体と磁性体からなる複合体を得るためには、虚数部透磁率μ″の大きな磁性体が必要となる。また、前記した不要輻射は、多くの場合、その成分が広い周波数範囲にわたっており、電磁障害に係る周波数成分の特定も困難な場合が少なくない。従って、前記電磁干渉抑制体についても、より広い周波数の不要輻射に対応できるものが望まれている。 Here, since the thickness d of the magnetic material is inversely proportional to μ ″ in a frequency band satisfying the relationship of μ ″> μ ′, thin electromagnetic interference suppression that meets the requirements for downsizing and weight reduction of the electronic device described above. In order to obtain a body, that is, a composite body composed of a shield body and a magnetic body, a magnetic body having a large imaginary part permeability μ ″ is necessary. In many cases, the above-mentioned unnecessary radiation has a wide component. In many cases, it is difficult to specify the frequency component related to electromagnetic interference over the frequency range, and therefore, the electromagnetic interference suppressor is also desired to be able to cope with a wider frequency of unnecessary radiation.
そこで、本発明の一つの技術的課題は、移動体通信機器をはじめとする高周波電子機器類内部での電磁波の干渉抑制に有効な薄厚の電磁干渉抑制体とそれに用いる複合磁性体及びその製造方法を提供することにある。 Therefore, one technical problem of the present invention is that a thin electromagnetic interference suppressor effective for suppressing interference of electromagnetic waves inside a high-frequency electronic device such as a mobile communication device, a composite magnetic body used therefor, and a method for manufacturing the same Is to provide.
また、本発明の他の技術的課題は、複雑な形状への対応や厳しい耐振動、衝撃要求への対応が可能である複合磁性体、その製造方法、及びそれを用いた電磁干渉抑制体を提供することにある。 In addition, another technical problem of the present invention is to provide a composite magnetic body capable of dealing with complicated shapes, severe vibration resistance, impact demands, a manufacturing method thereof, and an electromagnetic interference suppressor using the same. It is to provide.
本発明者らは、懸る要求に対応すべく広い周波数範囲にて磁気損失体として機能する磁性体、即ち、μ″>μ′なる周波数領域において、μ″が広い周波数範囲に亘って大きな値を示す磁性体の検討を行った。即ち、本発明者らは、以前に形状異方性を有する軟磁性体粉末において磁気共鳴により発現すると思われる数十MHzから数GHzに亘る磁気損失を利用する電磁干渉抑制体(特願平6−4864号、参照)を作製し、形状異方性の付与による電磁干渉抑制効果の改善を示した。ところで、この磁気共鳴の発現(周波数シフト)には、前記形状磁気異方性の他に結晶磁気異方性や各種誘導磁気異方性を利用することも可能であり、これらの総合による異方性の大きさ、即ち、異方性磁界(Hk)を制御することにより、所望の周波数に磁気共鳴を発現できることが示されている。本発明者らは、この点に新ためて着目し、周波数の異なる複数の磁気共鳴を発現させることにより、各々の磁気共鳴に対応して異なる周波数領域に出現する個々の磁気損失が重畳され、その結果、広帯域なμ″分散特性が得られるものと推測し、種々検討した結果、本発明をなすに至ったものである。 In order to meet the demands of the present inventors, a magnetic material that functions as a magnetic loss material in a wide frequency range, that is, in a frequency range of μ ″> μ ′, μ ″ has a large value over a wide frequency range. The magnetic material shown was examined. In other words, the present inventors have previously proposed an electromagnetic interference suppressor (Japanese Patent Application No. 6) that uses a magnetic loss ranging from several tens of MHz to several GHz that appears to be manifested by magnetic resonance in a soft magnetic powder having shape anisotropy. -4864 (see No. 4864), and showed an improvement in electromagnetic interference suppression effect by imparting shape anisotropy. By the way, for the manifestation (frequency shift) of this magnetic resonance, it is possible to utilize crystal magnetic anisotropy and various induced magnetic anisotropies in addition to the shape magnetic anisotropy. It has been shown that magnetic resonance can be developed at a desired frequency by controlling the magnitude of the sex, that is, the anisotropic magnetic field (Hk). The inventors have refocused on this point, and by expressing a plurality of magnetic resonances having different frequencies, individual magnetic losses appearing in different frequency regions corresponding to each magnetic resonance are superimposed, As a result, it is presumed that a broadband μ ″ dispersion characteristic can be obtained, and as a result of various studies, the present invention has been achieved.
本発明によれば、軟磁性体粉末と有機結合剤からなる電気的に非良導性の複合磁性体であって、前記複合磁性体は、互いに異なる大きさの異方性磁界(Hk)によってもたらされる磁気共鳴を少なくとも2つ有することを特徴とする複合磁性体が得られる。 According to the present invention, an electrically non-conductive composite magnetic material composed of soft magnetic powder and an organic binder, wherein the composite magnetic material is subjected to anisotropic magnetic fields (Hk) having different magnitudes. A composite magnetic body characterized in that it has at least two magnetic resonances is provided.
また、本発明によれば、実質的に前記複合磁性体からなる電磁干渉抑制体であって、前記複合磁性体の前記互いに異なる大きさの異方性磁界(Hk)に相応して相異なる周波数領域に出現する複数の磁気共鳴のうち、最も低い周波数領域に現れる磁気共鳴が、当該電磁干渉抑制体の電磁干渉抑制周波数帯域の下限よりも低い周波数領域にあることを特徴とする電磁干渉抑制体が得られる。 According to the present invention, there is provided an electromagnetic interference suppressor substantially composed of the composite magnetic body, and having different frequencies corresponding to the anisotropic magnetic fields (Hk) having different magnitudes of the composite magnetic body. Among the plurality of magnetic resonances appearing in the region, the magnetic resonance appearing in the lowest frequency region is in a frequency region lower than the lower limit of the electromagnetic interference suppressing frequency band of the electromagnetic interference suppressing member. Is obtained.
また、本発明によれば、前記電磁干渉抑制体において、前記軟磁性体粉末は、異なる大きさの磁気異方性を有する少なくとも2種の軟磁性体粉末の混合体であることを特徴とする電磁干渉抑制体が得られる。 According to the present invention, in the electromagnetic interference suppressor, the soft magnetic powder is a mixture of at least two soft magnetic powders having different magnetic anisotropies. An electromagnetic interference suppressor is obtained.
また、本発明によれば、前記電磁干渉抑制体において、前記軟磁性体粉末は、表面に酸化物層を備えていることを特徴とする電磁干渉抑制体が得られる。 According to the present invention, in the electromagnetic interference suppressor, an electromagnetic interference suppressor characterized in that the soft magnetic powder has an oxide layer on the surface.
また、本発明によれば、少なくとも2種の互いに異なる大きさの磁気異方性を有する軟磁性体粉末と有機結合剤とを混合し成形することによって、電気的に非良導性であって、互いに異なる大きさの異方性磁界(Hk)によってもたらされる磁気共鳴を少なくとも2つ有する複合磁性体を得ることを特徴とする複合磁性体の製造方法が得られる。 In addition, according to the present invention, at least two kinds of soft magnetic powders having different magnetic anisotropies and an organic binder are mixed and molded, thereby being electrically non-conducting. A method for producing a composite magnetic body characterized in that a composite magnetic body having at least two magnetic resonances caused by anisotropic magnetic fields (Hk) of different magnitudes is obtained.
また、本発明によれば、前記複合磁性体の製造方法において、前記軟磁性体粉末を、前記有機結合剤と混合する前段階、又は混合過程後にて気相徐酸法又は液相徐酸法によって酸素含有混合ガスにより表面酸化することを特徴とする複合磁性体の製造方法が得られる。 Further, according to the present invention, in the method for producing a composite magnetic body, the gas phase slow acid method or the liquid phase slow acid method is performed before or after the soft magnetic powder is mixed with the organic binder. Thus, a method for producing a composite magnetic body characterized in that the surface is oxidized with an oxygen-containing mixed gas can be obtained.
ここで、所望の磁気損失特性に対応する必要な大きさの異方性磁界(Hk)を与える複合磁性体を得るには、形状磁気異方性、結晶磁気異方性、誘導磁気異方性、あるいは磁気弾性効果(磁歪)による異方性のいずれか、あるいはその複数を有する軟磁性粉末を用いれば良い。即ち、本発明において、複数の互いに異なる周波数の磁気共鳴及びそれに対応する帯域拡張された磁気損失を得るためには、互いに異なる大きさの異方性磁界(Hk)を有する複数の磁性粉末を混合すればよい。 Here, in order to obtain a composite magnetic body that provides an anisotropic magnetic field (Hk) having a required magnitude corresponding to a desired magnetic loss characteristic, shape magnetic anisotropy, crystal magnetic anisotropy, induced magnetic anisotropy are obtained. Or a soft magnetic powder having one or more of anisotropy due to a magnetoelastic effect (magnetostriction) or a plurality thereof. That is, in the present invention, a plurality of magnetic powders having different anisotropic magnetic fields (Hk) are mixed to obtain a plurality of magnetic resonances having different frequencies and a corresponding band-expanded magnetic loss. do it.
これ以外に複数の磁気共鳴を得る手段として、以下に述べる粉末および粉末複合体特有の性質、あるいは粉末の粉砕・展延プロセスを積極的に利用することも可能である。 In addition to this, as a means for obtaining a plurality of magnetic resonances, it is also possible to positively utilize the following properties unique to powders and powder composites, or powder crushing and spreading processes.
即ち、第1に、単一原料種を特定の条件下で加工することにより得られる粉体特性の分化を利用する方法がある。第2に、粉体の粉砕・展延加工に用いる粉砕メディアをスチール球のような軟磁性メディアとすることで、メディアの磨耗により軟磁性の磨耗粉が混入する、いわゆる汚染現象を積極的に利用する方法がある。また、第3には、単一種粉末の複合体中での存在形態の違いを利用する方法がある。例えば、同一マトリクス中に一次粒子として存在する粒子群と、凝集してその内部のぬれが不十分で、そのために粒子間が極めて接近、あるいは接触している粒子群とでは、磁気的相互作用や配向挙動が異なるために異方性磁界が分散する。更には、試料の形状が薄膜状、シート状であれば実効的異方性磁界は試料形状による反磁界との代数和となるので、原料磁性粉末の配向制御も積極的に利用できる。 That is, firstly, there is a method that utilizes differentiation of powder characteristics obtained by processing a single raw material species under specific conditions. Secondly, by using soft magnetic media such as steel balls as the grinding media for powder crushing and spreading, the so-called contamination phenomenon in which soft magnetic wear powder is mixed due to media wear is actively promoted. There are ways to use it. Third, there is a method that utilizes the difference in the form of existence in a composite of a single type powder. For example, a group of particles that exist as primary particles in the same matrix and a group of particles that are agglomerated and have insufficient wettability inside them, so that the particles are in close proximity or in contact with each other. Since the orientation behavior is different, the anisotropic magnetic field is dispersed. Furthermore, since the effective anisotropic magnetic field is an algebraic sum with the demagnetizing field due to the sample shape if the sample shape is a thin film or sheet, the orientation control of the raw magnetic powder can be actively utilized.
本発明において利用する複数の異方性磁界を得る手段としては、これらのいずれの方法を用いても良いが、所望の磁気損失帯域が得られるように複数の異方性磁界を与えることが重要である。特に、その内、最も低周波数側に出現する磁気共鳴を与える異方性磁界については、虚数部透磁率(磁気損失)の分散が実数部透磁率の減少に伴って生じることを踏まえて、所望する電磁干渉抑制周波数帯域の下限よりも低い周波数領域に磁気共鳴を与える値に設定する必要がある。 Any of these methods may be used as means for obtaining a plurality of anisotropic magnetic fields used in the present invention. However, it is important to provide a plurality of anisotropic magnetic fields so as to obtain a desired magnetic loss band. It is. In particular, an anisotropic magnetic field that gives magnetic resonance that appears on the lowest frequency side is desired in view of the fact that the dispersion of the imaginary part permeability (magnetic loss) occurs as the real part permeability decreases. It is necessary to set a value that gives magnetic resonance in a frequency region lower than the lower limit of the electromagnetic interference suppression frequency band.
ここで、本発明において用いることのできる軟磁性粉末としては、高周波透磁率の大きな鉄アルミ珪素合金(センダスト)、鉄ニッケル合金(パーマロイ)、あるいはアモルファス合金等の金属軟磁性材料を粉砕、延伸〜引裂加工、あるいはアトマイズ造粒等により粉末化したものを代表として挙げることができるが、本発明の必要要素である複合磁性体の非良導性を軟磁性粉の高充填状態においても確保できるように、少なくともその表面が酸化され、それによって個々の粒子が電気的に隔離されることが望ましい。 Here, as a soft magnetic powder that can be used in the present invention, a metal soft magnetic material such as an iron aluminum silicon alloy (Sendust), an iron nickel alloy (Permalloy), or an amorphous alloy having a high high frequency permeability is pulverized and stretched. A typical example is powdered by tearing or atomizing granulation, etc., but the non-conductivity of the composite magnetic material, which is a necessary element of the present invention, can be ensured even in a high filling state of soft magnetic powder. In addition, it is desirable that at least the surface be oxidized, thereby electrically isolating the individual particles.
また、本発明の軟磁性粉末には、スピネル型フェライト、プレーナ型フェライト等の酸化物軟磁性体の粉末を用いることもでき、前記金属軟磁性粉末との混合使用も可能である。 In addition, the soft magnetic powder of the present invention may be a powder of an oxide soft magnetic material such as spinel type ferrite or planar type ferrite, and may be used in combination with the metal soft magnetic powder.
さらに、本発明の副材料として用いる有機結合剤としては、ポリエステル系樹脂、ポリエチレン樹脂、ポリ塩化ビニル系樹脂、ポリビニルブチラール樹脂、ポリウレタン樹脂、セルロース系樹脂、ABS樹脂、ニトリル−ブタジエン系ゴム、スチレン−ブタジエン系ゴム等の熱可塑性樹脂、あるいはそれらの共重合体、エポキシ樹脂、フェノール樹脂、アミド系樹脂、及びイミド系樹脂等の熱硬化性樹脂等を挙げることができる。 Furthermore, as an organic binder used as an auxiliary material of the present invention, polyester resin, polyethylene resin, polyvinyl chloride resin, polyvinyl butyral resin, polyurethane resin, cellulose resin, ABS resin, nitrile-butadiene rubber, styrene- Examples thereof include thermoplastic resins such as butadiene rubber, or copolymers thereof, epoxy resins, phenol resins, amide resins, and thermosetting resins such as imide resins.
以上、述べた本発明の構成要素を混練、分散し複合磁性体を得る手段には特に制限はなく、用いる結合剤の性質や工程の容易さを基準に好ましい方法を選択すればよい。 The means for kneading and dispersing the constituent elements of the present invention described above to obtain a composite magnetic material is not particularly limited, and a preferred method may be selected based on the properties of the binder used and the ease of the process.
また、本発明の複合磁性体および電磁干渉抑制体は、互いに異なる大きさの複数の異方性磁界(Hk)を有し、それに伴い相異なる周波数領域に複数の磁気共鳴が出現する。そのため、該複数の磁気共鳴に伴って相異なる周波数領域に現れる虚数部透磁率μ″が重畳され、その結果、広帯域なμ″分散特性を得ることができる。ここで、虚数部透磁率μ″は、電磁波の吸収に必要な磁気損失項であり、μ″の値が大きく且つ広帯域に亘っていることにより優れた電磁干渉抑制効果が現れる。 Further, the composite magnetic body and electromagnetic interference suppressor of the present invention have a plurality of anisotropic magnetic fields (Hk) having different sizes, and a plurality of magnetic resonances appear in different frequency regions accordingly. Therefore, the imaginary part permeability μ ″ appearing in different frequency regions with the plurality of magnetic resonances is superimposed, and as a result, a broadband μ ″ dispersion characteristic can be obtained. Here, the imaginary part permeability μ ″ is a magnetic loss term necessary for electromagnetic wave absorption, and an excellent electromagnetic interference suppression effect appears when the value of μ ″ is large and covers a wide band.
また、本発明に用いられる軟磁性粉末は、少なくともその表面が酸化されているために、粉末の充填率が高い場合においても個々の粒子が電気的に隔離された状態で存在することになり、良導性のバルク体にみられるような渦電流損失による周波数特性の劣化が少ないばかりでなく、空間とのインピーダンス不整合による表面での電磁波の反射が起こりにくくなり、高周波領域にて優れた電磁干渉抑制効果を発揮することができる。 In addition, since the soft magnetic powder used in the present invention is oxidized at least on its surface, even when the filling rate of the powder is high, individual particles are present in an electrically isolated state, Not only does the frequency characteristics deteriorate due to eddy current loss, as seen in a bulk material with good conductivity, but it also makes it difficult for reflection of electromagnetic waves on the surface due to impedance mismatch with space, and excellent electromagnetic properties in the high frequency range. Interference suppression effect can be exhibited.
本発明の複合磁性体およびそれを用いた電磁干渉抑制体は、互いに異なる大きさの複数の異方性磁界(Hk)を有し、それに伴い相異なる周波数領域に複数の磁気共鳴が出現するので、広帯域なμ″分散特性が得られる。この虚数部透磁率μ″は、電磁波の吸収に必要な磁気損失項であり、μ″の値が大きく且つ広帯域に亘っていることにより優れた電磁干渉抑制効果が現れる。即ち、移動体通信機器をはじめとする高周波電子機器類内部での電磁波の干渉抑制に有効な薄厚の電磁干渉抑制体を提供することができる。 The composite magnetic body of the present invention and the electromagnetic interference suppressor using the same have a plurality of anisotropic magnetic fields (Hk) having different sizes, and accordingly, a plurality of magnetic resonances appear in different frequency regions. A broadband μ ″ dispersion characteristic can be obtained. This imaginary part permeability μ ″ is a magnetic loss term necessary for electromagnetic wave absorption, and is excellent in electromagnetic interference due to a large μ ″ value and over a wide band. In other words, it is possible to provide a thin electromagnetic interference suppressor effective for suppressing interference of electromagnetic waves inside high-frequency electronic devices such as mobile communication devices.
さらに、本発明の複合磁性体およびそれを用いた電磁干渉抑制体は、その構成要素から判るように容易に可とう性を付与することが可能であり、複雑な形状への対応や厳しい耐振動、衝撃要求への対応が可能である。 Furthermore, the composite magnetic body of the present invention and the electromagnetic interference suppressor using the same can easily provide flexibility as can be seen from its constituent elements, and can cope with complex shapes and severe vibration resistance. It is possible to respond to shock demands.
以下、本発明の実施の形態について説明する。 Hereinafter, embodiments of the present invention will be described.
まず、本発明の実施の一形態による電磁干渉抑制体に用いられる複合磁性体とその原料である軟磁性粉末の製造方法の一例について説明する。 First, an example of a method for producing a composite magnetic body used for an electromagnetic interference suppressor according to an embodiment of the present invention and a soft magnetic powder as a raw material thereof will be described.
はじめに、水アトマイズ法により作製された平均粒径が異なる複数の鉄アルミ珪素合金粉末を用意し、アトライタ及びピンミルを用い様々な条件下にて延伸〜粉砕加工を行い、さらに炭化水素系有機溶媒中で酸素分圧35%の窒素−酸素混合ガスを導入しながら8時間撹拌し、液相徐酸処理した後、分級処理を施し異方性磁界(Hk)の異なる複数の粉末試料を得た。ここで得られた粉末を表面分析した結果、Al−O及びSi−O結合が明確に確認され、試料粉末の表面において酸化皮膜の存在が認められた。 First, a plurality of iron aluminum silicon alloy powders with different average particle diameters prepared by the water atomization method are prepared, stretched and pulverized under various conditions using an attritor and a pin mill, and further in a hydrocarbon-based organic solvent. Then, the mixture was stirred for 8 hours while introducing a nitrogen-oxygen mixed gas having an oxygen partial pressure of 35%, subjected to liquid phase gradual acid treatment, and then subjected to classification treatment to obtain a plurality of powder samples having different anisotropic magnetic fields (Hk). As a result of surface analysis of the obtained powder, Al—O and Si—O bonds were clearly confirmed, and the presence of an oxide film was observed on the surface of the sample powder.
なお、延伸〜粉砕加工処理された鉄アルミ珪素合金粉末を減圧乾燥し、これを酸素分圧20%の窒素−酸素混合ガス雰囲気中で気相徐酸した試料についてもその表面にAl−O及びSi−O結合が検出され、本発明に用いることのできる少なくともその表面が酸化された軟磁性粉末が液相あるいは気相徐酸法にて製造できることが確認された。 Note that a sample obtained by drying the stretched and pulverized iron-aluminum-silicon alloy powder under reduced pressure and subjecting this to a gas-phase gradual acid in a nitrogen-oxygen mixed gas atmosphere having an oxygen partial pressure of 20% also has Al-O and The Si—O bond was detected, and it was confirmed that a soft magnetic powder having at least a surface that can be used in the present invention can be produced by a liquid phase or gas phase slow acid method.
本発明の一実施の形態に係る電磁干渉抑制体の特性を検証するにあたり、これらの粉末試料を用いて以下に述べる複合磁性体を作製し、μ−f特性及び電磁干渉抑制効果を調べた。ここで、μ−f特性の測定には、トロイダル形状に加工された複合磁性体試料を用いた。これを1ターンコイルを形成するテストフィクスチャに挿入し、インピーダンスを計測することによりμ′及びμ″を求めた。 In verifying the characteristics of the electromagnetic interference suppressor according to the embodiment of the present invention, a composite magnetic body described below was prepared using these powder samples, and the μ-f characteristic and the electromagnetic interference suppression effect were examined. Here, for measuring the μ-f characteristic, a composite magnetic material sample processed into a toroidal shape was used. This was inserted into a test fixture forming a one-turn coil, and μ ′ and μ ″ were obtained by measuring impedance.
一方、電磁干渉抑制効果の検証は、図1に示される評価系により行い、電磁干渉抑制体10の試料には、銅板8が裏打ちされた厚さ2mmで、一辺の長さが20cmの複合磁性体2を用いた。ここで、電磁界波源用発振器6を用いた波源用素子及び受信用素子には、ループ径1.5mmの電磁界送信用及び電磁界受信用の微小ループアンテナ4,5を用い、結合レベルの測定にはネットワークアナライザ(電磁界強度測定器)7を使用した。
On the other hand, the electromagnetic interference suppression effect is verified by the evaluation system shown in FIG. 1, and the sample of the electromagnetic
(実施例1)
表1の配合からなる軟磁性体ペーストを調合し、これをドクターブレード法により製膜し、熱プレスを施した後に85℃にて24時間キュアリングを行い、評価用試料1を得た。
Example 1
A soft magnetic paste having the composition shown in Table 1 was prepared, formed into a film by a doctor blade method, subjected to hot pressing, and then cured at 85 ° C. for 24 hours to obtain
なお、得られた試料1を振動型磁力計並びに走査型電子顕微鏡を用いて解析したところ、磁化容易軸及び粒子配向方向は試料膜面内方向であった。
The obtained
(実施例2)
表2の配合からなる軟磁性体ペーストを調合し、実施例1と同様な方法にて評価用試料2を得た。
(Example 2)
A soft magnetic paste having the composition shown in Table 2 was prepared, and an
なお、得られた試料2を振動型磁力計並びに走査型電子顕微鏡を用いて解析したところ、磁化容易軸及び粒子配向方向は試料膜面内方向であった。
In addition, when the obtained
(比較例1)
表3の配合からなる軟磁性体ペーストを調合し、実施例1と同様な方法にて評価用試料3を得た。
(Comparative Example 1)
A soft magnetic paste having the composition shown in Table 3 was prepared, and an
なお、得られた試料3を振動型磁力計並びに走査型電子顕微鏡を用いて解析したところ、磁気的には、ほぼ等方性であった。
When the obtained
実施例1、実施例2、及び比較例で得られた各試料のμ−f特性を図2〜図4に示す。 The μ-f characteristics of the samples obtained in Example 1, Example 2, and Comparative Example are shown in FIGS.
図2及び図3は、各々本発明の実施例1、実施例2である試料1及び試料2のμ−f特性であり、いずれの試料についても高周波領域においてμ″の値が大きく且つ広帯域に亘っていることが判る。
2 and 3 show the μ-f characteristics of
一方、図4に比較例として示した従来の試料3では、μ−f特性は複合磁性体にみられる一般的な傾向を示しており、μ″の分布は広くない。
On the other hand, in the
即ち、これらの結果より、本発明の実施例1、実施例2に係る複合磁性体は、高周波領域において広帯域な磁気損失特性を有していることが判る。 That is, from these results, it can be seen that the composite magnetic bodies according to Example 1 and Example 2 of the present invention have a broadband magnetic loss characteristic in a high frequency region.
次に、各試料の粉末充填率、表面抵抗、μ″分布、及び電磁干渉抑制効果を表4に示す。ここで、表面抵抗はASTM−D−257法による測定値であり、電磁干渉抑制効果の値は、銅板を基準(0dB)としたときの信号減衰量である。 Next, the powder filling rate, surface resistance, μ ″ distribution, and electromagnetic interference suppression effect of each sample are shown in Table 4. Here, the surface resistance is a measured value by the ASTM-D-257 method, and the electromagnetic interference suppression effect. The value of is a signal attenuation when the copper plate is used as a reference (0 dB).
表4より、以下に述べる効果が明白である。 From Table 4, the effects described below are clear.
即ち、本発明の実施例1、実施例2に係る試料1、試料2、及び比較例に係る試料3ともに、表面抵抗の値が107〜108Ωとなっており、少なくとも表面が酸化された磁性粉末を用いることによって、複合磁性体を非良導性とすることができ、導体やバルクの金属磁性体等にてみられるようなインピーダンス不整合による電磁波の表面反射を抑制できる。
That is, the
更に、本発明の実施例1、実施例2に係る試料1及び2では、粉末の充填率が比較例1に係る試料3に比べて低いにもかかわらず良好な電磁干渉抑制効果を示しており、本発明によるμ″分布の拡張効果が電磁干渉抑制に極めて有効であることが理解できる。
Furthermore,
なお、本発明において用いられる軟磁性体の少なくともその表面を酸化させることの効果については、前記以外に次の効果も期待できる。 In addition to the above, the following effects can also be expected for the effect of oxidizing at least the surface of the soft magnetic material used in the present invention.
例えば、粉体表面酸化層(=非磁性層)の厚さを制御することによって磁性体層(=非酸化層)の厚みを変えることができ、異方性磁界(Hk)の値を制御することが可能となる。 For example, the thickness of the magnetic layer (= non-oxidized layer) can be changed by controlling the thickness of the powder surface oxidized layer (= non-magnetic layer), and the value of the anisotropic magnetic field (Hk) is controlled. It becomes possible.
2 複合磁性体
4,5 微小ループアンテナ
6 電磁界波源用発振器
7 電磁界強度測定器
8 銅板
10 電磁干渉抑制体
2 Composite
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