JP6044021B2 - Noise suppression member - Google Patents
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Description
本発明は、回路から放射される電磁波を遮断するためのノイズ抑制部材に関する。 The present invention relates to a noise suppressing member for blocking electromagnetic waves radiated from a circuit.
携帯電話等の電子機器の回路では、回路から放射された電磁波が電磁干渉を起こすという問題がある。近年、電子機器の小型化や高性能化の要望にこたえる形で、回路基板や部品の高密度実装化が進んでおり、回路基板間や部品間の間隔が小さくなることに起因して、電磁干渉の問題が深刻となっている。このような電磁干渉の対策の一つとして、従来、回路の近傍に、結合材中にフェライト粉末を分散して作製されたノイズ抑制シートを配置したり（例えば、特許文献１参照）、回路の近傍に、フェライト粉末を焼結して作製されたノイズ抑制シートを配置したりするもの（例えば、特許文献２参照）があった。 In a circuit of an electronic device such as a mobile phone, there is a problem that electromagnetic waves radiated from the circuit cause electromagnetic interference. In recent years, high-density mounting of circuit boards and components has been progressing in response to demands for miniaturization and high performance of electronic devices, and the distance between circuit boards and components has been reduced. The problem of interference has become serious. As one of the countermeasures against such electromagnetic interference, a noise suppression sheet prepared by dispersing ferrite powder in a binder has been conventionally arranged in the vicinity of a circuit (for example, see Patent Document 1), In the vicinity, a noise suppression sheet prepared by sintering ferrite powder is disposed (for example, see Patent Document 2).
これら特許文献１や特許文献２に記載のノイズ抑制シートは、あまり薄くしすぎると厚さに比例して電磁干渉抑制効果が低下し、さらに破損する虞があるため、１ミリ程度の厚みが必要となる。このため、ノイズ抑制シートを回路の近傍に配置する際に、回路基板の実装に支障をきたすことがあるという課題があった。しかも、回路が高周波集積回路（Ｒａｄｉｏ Ｆｒｅｑｕｅｎｃｙ Ｉｎｔｅｇｒａｔｅｄ Ｃｉｒｃｕｉｔ：ＲＦＩＣ）である場合、回路から放射される電磁波だけでなく、通信周波数帯で発生する信号も遮断されるため、通信品質の低下が懸念されるという課題もあった。 Since the noise suppression sheets described in Patent Document 1 and Patent Document 2 are too thin, the electromagnetic interference suppression effect is reduced in proportion to the thickness and may be damaged. It becomes. For this reason, when arrange | positioning a noise suppression sheet | seat in the vicinity of a circuit, there existed a subject that the mounting of a circuit board might be obstructed. In addition, when the circuit is a radio frequency integrated circuit (RFIC), not only electromagnetic waves radiated from the circuit but also signals generated in the communication frequency band are blocked, and there is a concern that communication quality may be degraded. There was also a problem.
本発明は、このような課題に鑑みてなされたものであって、回路基板の実装の妨げとならず、電磁干渉を抑制しつつ通信品質を良好に維持できるノイズ抑制部材を提供することを目的としている。 The present invention has been made in view of such problems, and it is an object of the present invention to provide a noise suppression member that does not hinder mounting of a circuit board and that can maintain good communication quality while suppressing electromagnetic interference. It is said.
本発明に係るノイズ抑制部材は、回路から放射される電磁波を遮断するためのノイズ抑制部材であって、強磁性共鳴周波数を有し、前記回路に近接配置された磁性薄膜を備え、前記強磁性共鳴周波数以上の周波数帯で、前記磁性薄膜内部の磁気抵抗と、前記磁性薄膜からの漏洩磁束の経路の磁気抵抗との和が０となるよう構成されており、前記回路の通信周波数帯が、前記磁性薄膜のシールド効果が負となる所定の周波数範囲内に含まれることを特徴とする。
Noise suppression member according to the present invention is a noise suppression member for blocking electromagnetic waves radiated from the circuit, has a ferromagnetic resonance frequency, comprising a magnetic thin film which is disposed close to the circuit, the ferromagnetic The sum of the magnetic resistance inside the magnetic thin film and the magnetic resistance of the leakage magnetic flux path from the magnetic thin film is configured to be 0 in a frequency band equal to or higher than the resonance frequency, and the communication frequency band of the circuit is The magnetic thin film is included in a predetermined frequency range in which the shielding effect is negative .
本発明に係るノイズ抑制部材は、前記磁性薄膜から成り、前記磁性薄膜は、前記強磁性共鳴周波数以上の周波数帯域で比透磁率の実部が負となる軟磁性薄膜であることが好ましい。また、この場合、前記軟磁性薄膜は、ＮｉＦｅ、ＣｏＦｅＢ、ＣｏＣｒＮｂ、ＣｏＺｒＮｂ、ＮｉＦｅＮｂ、ＣｏＺｒＯ、ＣｏＡｌＯ、ＣｏＰｄＡｌＯから選択される１または複数の材料で構成されていることが好ましい。また、前記軟磁性薄膜は、厚みが、１００ｎｍ〜５μｍであることが好ましい。また、前記軟磁性薄膜と前記回路との間隔が、２μｍ〜１０μｍであることが好ましい。
Noise suppression member according to the present invention is made from the magnetic thin film, the magnetic thin film is preferably the real part of the relative permeability in the ferromagnetic resonance frequency or higher frequency band is soft magnetic thin film serving as a negative. In this case, the soft magnetic thin film is preferably made of one or more materials selected from NiFe, CoFeB, CoCrNb, CoZrNb, NiFeNb, CoZrO, CoAlO, and CoPdAlO. The soft magnetic thin film preferably has a thickness of 100 nm to 5 μm. Moreover, it is preferable that the space | interval of the said soft-magnetic thin film and the said circuit is 2 micrometers-10 micrometers.
本発明のノイズ抑制部材を用いることで、ノイズ抑制部材の回路基板への実装が容易となる。しかも、通信周波数帯の近傍の周波数でシールド効果が負になるため、信号が遮断されずに通信品質を良好に維持できながらも、通信周波数帯の近傍以外の周波数でシールド効果が正になるため、回路から放射された電磁波を遮断して電磁干渉を効果的に抑制できる。このように、本発明によれば、回路基板の実装の妨げとならず、電磁干渉を抑制しつつ通信品質を良好に維持できるノイズ抑制部材を提供することができる。 By using the noise suppression member of the present invention, the noise suppression member can be easily mounted on the circuit board. Moreover, since the shielding effect becomes negative at frequencies near the communication frequency band, the shielding effect becomes positive at frequencies other than the vicinity of the communication frequency band while maintaining good communication quality without blocking the signal. Electromagnetic interference can be effectively suppressed by blocking electromagnetic waves radiated from the circuit. As described above, according to the present invention, it is possible to provide a noise suppression member that does not hinder the mounting of the circuit board and that can satisfactorily maintain communication quality while suppressing electromagnetic interference.
以下、本発明の実施の形態のノイズ抑制部材を図面に基づいて詳細に説明する。
図１、図３に示すように、ガラスエキポシ製（Ｇｌａｓｓ ｅｐｏｘｙ）の基板Ａの上に、グラウンド（Ｇｒｏｕｎｄ）に接続されたコプレーナ線路（Ｃｏｐｌａｎａｒ ｔｒａｎｓｍｉｓｓｉｏｎ ｌｉｎｅ）Ｂ（回路の一例）が配置されている。コプレーナ線路Ｂの寸法は、信号線幅１６０μｍ、厚み３５μｍ、グラウンドギャップ３０μｍとし、直流抵抗を無視した場合に特性インピーダンスが５０Ωに整合するよう設計した。このコプレーナ線路Ｂ上に、厚み２ｍｍのガラス基板（Ｇｌａｓｓ）Ｃの上に製膜した膜厚０．２５μｍの磁性薄膜（Ｃｏ８５Ｚｒ３Ｎｂ１２膜、ＣｏＺｒＮｂ ｆｉｌｍ）Ｄを、コプレーナ線路Ｂと磁性薄膜が近接するよう配置した。磁性薄膜（Ｍａｇｎｅｔｉｃ ｆｉｌｍ）Ｄは、本発明の実施の形態のノイズ抑制部材を成している。
Hereinafter, the noise suppression member of embodiment of this invention is demonstrated in detail based on drawing.
As shown in FIGS. 1 and 3, a coplanar transmission line B (an example of a circuit) connected to a ground is disposed on a glass epoxy substrate A. . The dimensions of the coplanar line B were designed such that the signal line width was 160 μm, the thickness was 35 μm, the ground gap was 30 μm, and the characteristic impedance matched to 50Ω when the DC resistance was ignored. On this coplanar line B, a magnetic thin film (Co 85 Zr 3 Nb 12 film, CoZrNb film) D having a thickness of 0.25 μm formed on a glass substrate (Glass) C having a thickness of 2 mm is formed with the coplanar line B and a magnetic film. The thin films were placed close together. A magnetic thin film (Magnetic film) D forms a noise suppressing member according to the embodiment of the present invention.
尚、ＣｏＺｒＮｂの組成比は、Ｃｏ８５Ｚｒ３Ｎｂ１２に限られるものではない。また、磁性薄膜Ｄとして、ＮｉＦｅ、ＣｏＦｅＢ、ＣｏＣｒＮｂ、ＣｏＺｒＮｂ、ＮｉＦｅＮｂ、ＣｏＺｒＯ、ＣｏＡｌＯ、ＣｏＰｄＡｌＯ等の軟磁性薄膜も利用可能である。膜厚は、０．２５μｍに限られるものではなく、１００ｎｍ〜５μｍの範囲であればよい。 The composition ratio of CoZrNb is not limited to Co 85 Zr 3 Nb 12 . Further, as the magnetic thin film D, soft magnetic thin films such as NiFe, CoFeB, CoCrNb, CoZrNb, NiFeNb, CoZrO, CoAlO, and CoPdAlO can be used. The film thickness is not limited to 0.25 μm and may be in the range of 100 nm to 5 μm.
この磁性薄膜Ｄの周波数特性を、図２に示す。図２に示すように、比透磁率（Ｒｅｌａｃｔｉｖｅ Ｐｅｍｅａｂｉｌｉｔｙ）は０．１ＧＨｚにおいて７００程度、強磁性共鳴周波数ｆｒは１．１ＧＨｚである。アジレント製のネットワークアナライザ（Ｎｅｔｗｏｒｋ Ａｎａｌｙｚｅｒ）Ｅを用いて、この磁性薄膜Ｄのシールド効果を計測した。図３に示すように、ネットワークアナライザＥのポート１（Ｐｏｒｔ １）より、０ｄＢｍの電力をコプレーナ線路Ｂの一端から入力し、他端を５０Ω抵抗により終端させ、コプレーナ線路Ｂの上方に配置されたシールディドループコイル型の磁界プローブ（Ｍａｇｎｅｔｉｃ ｆｉｅｌｄ ｐｒｏｂｅ）Ｆを用いて、ネットワークアナライザＥのポート２（Ｐｏｒｔ ２）で信号を検出した。シールド効果（ＳＥ）を下記の（１）式で評価した。 The frequency characteristics of this magnetic thin film D are shown in FIG. As shown in FIG. 2, the relative permeability (Relactive Pemeability) is about 700 at 0.1 GHz, the ferromagnetic resonance frequency f r is 1.1 GHz. The shielding effect of the magnetic thin film D was measured using a network analyzer (Network Analyzer) E manufactured by Agilent. As shown in FIG. 3, 0 dBm of power is input from one end of the coplanar line B from the port 1 (Port 1) of the network analyzer E, and the other end is terminated by a 50Ω resistor, and is disposed above the coplanar line B. A signal was detected at port 2 (Port 2) of the network analyzer E by using a shielded loop coil type magnetic field probe F. The shielding effect (SE) was evaluated by the following formula (1).
図４に示すように、磁性薄膜Ｄの漏洩磁束を含めた磁気回路をモデルとして、シールド効果を計算した。特定の周波数帯域において、磁束が磁性薄膜Ｄを透過する現象の理解を行うため、磁性薄膜Ｄ内外の磁気抵抗の周波数特性を考察した。ここで、Ｒ’ｍおよびＲ’’ｍは、それぞれ磁性薄膜Ｄ内の磁気抵抗の実部および虚部を示している。ＲｌｐおよびＲｌｖは、それぞれ磁性薄膜Ｄからの漏洩磁束の磁気抵抗（Ｒｅｌｕｃｔａｎｃｅ ｏｆ ｌｅａｋａｇｅ ｆｌｕｘ）を示している。ＲｄｌおよびＲｄｖは、信号線周りの磁気抵抗を示している。ＲｌｐおよびＲｌｖの導出には、パーミアンス法を用いた。このとき、信号線を流れる伝導電流は周波数に対して一定値とし、磁性薄膜Ｄ内のシールド効果に対する渦電流の影響は小さいものと仮定した。 As shown in FIG. 4, the shielding effect was calculated using a magnetic circuit including the leakage magnetic flux of the magnetic thin film D as a model. In order to understand the phenomenon of magnetic flux passing through the magnetic thin film D in a specific frequency band, the frequency characteristics of the magnetoresistance inside and outside the magnetic thin film D were considered. Here, R ′ m and R ″ m indicate the real part and the imaginary part of the magnetic resistance in the magnetic thin film D, respectively. R lp and R lv indicate the reluctance of leakage flux from the magnetic thin film D, respectively. R dl and R dv indicate the magnetic resistance around the signal line. The permeance method was used to derive R lp and R lv . At this time, it was assumed that the conduction current flowing through the signal line was a constant value with respect to the frequency, and the influence of the eddy current on the shielding effect in the magnetic thin film D was small.
図５に示すように、シールド効果の計測値（Ｍｅａｓ．）と計算値（Ｃａｌｃ．）とを比較して、このモデルの妥当性を検討し、磁性薄膜Ｄを用いた帯域通過フィルタのメカニズムを実証した。シールド効果は、磁性薄膜Ｄの強磁性共鳴周波数である１．１ＧＨｚまでは２〜４ｄＢであり、磁性薄膜Ｄのシールド効果が得られている。一方、シールド効果は、１．１〜１．５ＧＨｚまで単調に減少し、最小となった後に上昇した。１．５ＧＨｚでは、シールド効果が負となっており、この周波数帯においては、磁束が磁性薄膜Ｄを透過している。また、計算値は、計測値と傾向がよく一致しており、特に磁束を透過する周波数帯域についてはほぼ一致している。 As shown in FIG. 5, the measured value (Meas.) And the calculated value (Calc.) Of the shielding effect are compared to examine the validity of this model, and the mechanism of the bandpass filter using the magnetic thin film D is examined. Demonstrated. The shielding effect is 2 to 4 dB up to 1.1 GHz which is the ferromagnetic resonance frequency of the magnetic thin film D, and the shielding effect of the magnetic thin film D is obtained. On the other hand, the shielding effect decreased monotonically from 1.1 to 1.5 GHz, and increased after reaching a minimum. At 1.5 GHz, the shielding effect is negative, and the magnetic flux passes through the magnetic thin film D in this frequency band. In addition, the calculated values tend to agree well with the measured values, and in particular, the frequency band that transmits the magnetic flux substantially agrees.
図６に、磁性薄膜Ｄ内外の磁気抵抗（Ｒｅｌｕｃｔａｎｃｅ）の周波数特性を示す。図６の黒の実線（Ｒ’ｍ）は、磁性薄膜Ｄ内部の磁気抵抗の実部を示し、灰色の実線（Ｒｌ）は、漏洩磁束の経路における磁気抵抗を示している。図６に示すように、膜固有の強磁性共鳴周波数１．１ＧＨｚ以上においては、磁性薄膜Ｄの比透磁率が負となることから、磁気抵抗内部の磁束は、周波数範囲において負の値となり、単調減少する。その結果、膜固有の強磁性共鳴周波数以上の周波数帯域において、磁性薄膜Ｄの磁気抵抗と漏洩磁束の経路の磁気抵抗との和が０となる所定の周波数帯ｆｔが存在する。このことから、磁性薄膜Ｄ及び漏洩磁束の経路において、磁気回路が電気回路の共振現象に近い現象が発生し、膜内を流れる磁束および漏洩磁束が増大し、図５に示すように、シールド効果が負となることが明らかとなった。このとき、磁性薄膜Ｄのシールド効果が負となる所定の周波数範囲Ｗ内に、高周波集積回路の通信周波数帯が含まれることが好ましい。このように構成すれば、信号が遮断されずに通信品質を良好に維持できながらも、回路から放射された電磁波を遮断して電磁干渉を効果的に抑制できる。 FIG. 6 shows the frequency characteristics of the magnetic resistance (Reluctance) inside and outside the magnetic thin film D. The black solid line (R ′ m ) in FIG. 6 indicates the real part of the magnetic resistance inside the magnetic thin film D, and the gray solid line (R 1 ) indicates the magnetic resistance in the leakage magnetic flux path. As shown in FIG. 6, the magnetic permeability inside the magnetic resistance becomes negative in the frequency range because the relative permeability of the magnetic thin film D becomes negative at a film-specific ferromagnetic resonance frequency of 1.1 GHz or higher. Monotonously decreases. As a result, there is a predetermined frequency band ft in which the sum of the magnetic resistance of the magnetic thin film D and the magnetic resistance of the leakage flux path is zero in a frequency band equal to or higher than the ferromagnetic resonance frequency inherent in the film. Therefore, in the magnetic thin film D and the leakage magnetic flux path, a phenomenon occurs in which the magnetic circuit is close to the resonance phenomenon of the electric circuit, and the magnetic flux and the leakage magnetic flux flowing in the film increase. As shown in FIG. Became negative. At this time, it is preferable that the communication frequency band of the high-frequency integrated circuit is included in a predetermined frequency range W in which the shielding effect of the magnetic thin film D is negative. If comprised in this way, although electromagnetic waves radiated | emitted from the circuit are interrupted | blocked, electromagnetic interference can be suppressed effectively, although communication quality is favorably maintained without being interrupted | blocked.
本発明は、上記実施の形態に限定されるものではなく、特許請求の範囲に記載した発明の範囲内で種々の変形が可能であり、それらも本発明の範囲内に含まれることはいうまでもない。 The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these are also included in the scope of the present invention. Nor.
Ａ 基板
Ｂ コプレーナ線路
Ｃ ガラス基板
Ｄ 磁性薄膜
Ｅ ネットワークアナライザ
Ｆ シールディドループコイル型の磁界プローブ
ｆｔ 所定の周波数帯
Ｗ 所定の周波数範囲
A substrate B coplanar line C glass substrate D magnetic thin film E network analyzer F shielded loop coil type magnetic field probe ft predetermined frequency band W predetermined frequency range
Claims (5)
強磁性共鳴周波数を有し、前記回路に近接配置された磁性薄膜を備え、
前記強磁性共鳴周波数以上の周波数帯で、前記磁性薄膜内部の磁気抵抗と、前記磁性薄膜からの漏洩磁束の経路の磁気抵抗との和が０となるよう構成されており、
前記回路の通信周波数帯が、前記磁性薄膜のシールド効果が負となる所定の周波数範囲内に含まれることを
特徴とするノイズ抑制部材。 A noise suppressing member for blocking electromagnetic waves radiated from a circuit,
A magnetic thin film having a ferromagnetic resonance frequency and disposed in close proximity to the circuit;
In the frequency band equal to or higher than the ferromagnetic resonance frequency , the sum of the magnetoresistance in the magnetic thin film and the magnetoresistance of the leakage magnetic flux path from the magnetic thin film is configured to be 0 ,
The noise suppression member , wherein a communication frequency band of the circuit is included in a predetermined frequency range in which the shielding effect of the magnetic thin film is negative .
前記磁性薄膜は、前記強磁性共鳴周波数以上の周波数帯域で比透磁率の実部が負となる軟磁性薄膜であることを
特徴とする請求項１記載のノイズ抑制部材。 Consisting of the magnetic thin film,
The magnetic thin film, the noise suppression element according to claim 1, wherein the real part of the relative permeability in the ferromagnetic resonance frequency or higher frequency band is soft magnetic thin film serving as a negative.
5. The noise suppression member according to claim 2 , wherein an interval between the soft magnetic thin film and the circuit is 2 μm to 10 μm.
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| JP2008204086A (en) * | 2007-02-19 | 2008-09-04 | Shin Etsu Polymer Co Ltd | Manufacturing method of electronic equipment |
| WO2009128310A1 (en) * | 2008-04-18 | 2009-10-22 | 株式会社村田製作所 | Functional substrate |
| JP5082060B2 (en) * | 2008-05-22 | 2012-11-28 | 学校法人明星学苑 | Low characteristic impedance power supply / ground pair line structure |
| JP2010135567A (en) * | 2008-12-04 | 2010-06-17 | Tohoku Univ | Radio wave absorbing material |
| JP5136914B2 (en) * | 2010-03-31 | 2013-02-06 | Ｎｅｃインフロンティア株式会社 | Wireless LAN terminal, automatic handover threshold optimization method for wireless LAN terminal, and optimization program thereof |
| JP2012038807A (en) * | 2010-08-04 | 2012-02-23 | Toshiba Corp | Electromagnetic shield sheet |
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