JP2005033156A - Electromagnetic wave absorption sheet, electronic apparatus, and method of manufacturing electromagnetic wave absorption sheet - Google Patents
Electromagnetic wave absorption sheet, electronic apparatus, and method of manufacturing electromagnetic wave absorption sheet Download PDFInfo
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Abstract
Description
本発明は、本発明は、強磁性体を用いた電磁波吸収シート、該電磁波吸収シートを備えた電子機器および電磁波吸収シートの製造方法に関する。 The present invention relates to an electromagnetic wave absorbing sheet using a ferromagnetic material, an electronic device including the electromagnetic wave absorbing sheet, and a method of manufacturing the electromagnetic wave absorbing sheet.
近年、インターネット利用をはじめとして、パソコン、自動車のエレクトロニックコントロールユニット、光モジュールや携帯電話あるいは携帯情報端末、高度道路情報システム、ブルートゥ−スなどＧＨｚ帯の高いクロック周波数を持つＣＰＵを利用した電子機器や電波を利用した情報通信機器が普及してきており、ユビキタス社会が訪れてきている。しかし、これら情報機器の普及に伴って、これら情報機器から放射される電磁波がもたらす、他の電子機器への誤作動や、人体への影響が問題とされてきている。
そのため、電子機器には、誤作動を起こさないこと、他の電子機器や人体に影響を与えないように、電磁波をできるだけ放出しないこと、外部から電磁波を受けても誤作動しないことが求められ、電子機器に対し、電磁波を反射あるいは吸収する電磁波遮蔽を施すことが行われている。
In recent years, electronic devices such as personal computers, electronic control units for automobiles, optical modules, mobile phones or portable information terminals, intelligent road information systems, Bluetooth, and other electronic devices using CPUs with a high clock frequency in the GHz band, including the use of the Internet. Information and communication equipment using radio waves has become widespread, and a ubiquitous society has come. However, with the widespread use of these information devices, malfunctions to other electronic devices caused by electromagnetic waves radiated from these information devices and effects on the human body have become problems.
For this reason, electronic devices are required not to malfunction, not to emit electromagnetic waves as much as possible so as not to affect other electronic devices and human bodies, and not to malfunction even when receiving electromagnetic waves from the outside. Electronic devices are shielded against electromagnetic waves that reflect or absorb electromagnetic waves.
電子機器、特に携帯可能な電子機器は、多機能、高性能化、小型化、軽量化が求められ、電磁波吸収においても同様で、堅牢で吸収効率がよく、小スペースで軽量であるものが求められている。 Electronic devices, especially portable electronic devices, are required to have multiple functions, higher performance, smaller size, and lighter weight. The same applies to electromagnetic wave absorption, and they must be robust, have good absorption efficiency, be small in space and lightweight. It has been.
従来より行われている導体シールドでは、不要輻射源からの反射による電磁結合が助長されるので、磁性体の磁気損失、すなわち虚数部透磁率μ”を利用した不要輻射の抑制が有効であるとして、軟磁性体扁平粉の厚みが表皮深さより薄く、充分なアスペクト比を有し、磁性体表面を不導体化した磁性体粉を有機結合剤中に約９５質量％加えてなる、効率のよい電磁波吸収特性を有し、可撓性を有する電磁波吸収体の提案がある（例えば、特許文献１参照。）。この特許文献１の実施例においては評価にあたって銅板で裏打ちされた電磁波吸収体を用いており、この電磁波吸収体の厚みは測定用銅板込みで２ｍｍとされている。
In conventional conductor shields, electromagnetic coupling due to reflection from unwanted radiation sources is promoted. Therefore, suppression of unwanted radiation using magnetic loss of magnetic material, that is, imaginary part permeability μ ”is effective. The soft magnetic flat powder is thinner than the skin depth, has a sufficient aspect ratio, and is obtained by adding about 95% by mass of a magnetic powder with a non-conductive magnetic surface to the organic binder. There is a proposal of an electromagnetic wave absorber having electromagnetic wave absorption characteristics and flexibility (see, for example,
また、セラミック相と強磁性超微結晶相とを含んでなる超微結晶磁性膜からなる電磁波吸収体の提案、すなわち、強磁性元素とセラミック元素をマグネトロンスパッタリングで基板上に製膜し、低温でアニールすることにより高抵抗のセラミック層中に強磁性体からなる超微結晶を析出させ、アイソレートしてなる電磁波吸収体の提案がある。この電磁波吸収体は、１００ＭＨｚ〜１０ＧＨｚの高周波帯域で、電気抵抗が高く、渦電流による電磁波の反射が抑えられ、虚数部透磁率が大きいため優れた電磁波吸収特性を有するとされている（例えば、特許文献２参照。）。
しかし、特許文献１記載の電磁波吸収体はその厚みが銅板込みで２ｍｍであり、電磁波吸収体自体のシート厚みが１ｍｍ以上と厚く、しかもその９５質量％が鉄などの強磁性体からなるので重く、軽量化が達成されたとはいえない。また、有機結合剤の量が少ないので堅牢性、可撓性も充分とはいえない。さらに、軟磁性体粉の扁平化や表面の不導体化に手間を要するため軟磁性体扁平粉は高価なものとなり、これを多量に用いるので電磁波吸収体も高価なものとなり、産業上満足のいくものではなかった。
また、特許文献２の電磁波吸収体においては、セラミック相中に強磁性超微結晶を生成させるためには高温の熱処理が必要とされている。特許文献２の実施例ではスライドガラス上にＲＦマグネトロンスパッタ法でセラミック／強磁性元素の膜を製膜し、２００〜３５０℃の熱処理をして強磁性超微結晶を形成させている。特許文献２では有機フィルム上に作製することを考慮しているものの、有機フィルムとしては高耐熱有機フィルムを用いざるを得ない。高耐熱有機フィルムは価格が高く、高価なものとなる。さらに、仮に高耐熱有機フィルム上にこのような強磁性超微結晶相を形成させたとしても、有機フィルムと生成されたセラミックスとでは熱膨張率に大きな差があり、クラックが生じやすく、可撓性や堅牢性が高いというものではない。
このような状況から、電子機器や電子部品などに、組み込み応用が容易で、電磁波吸収特性が良く、小型、軽量で、可撓性があり、堅牢な電磁波吸収体は、未だ満足のいくものがなく、求められている。
However, the electromagnetic wave absorber described in
In addition, in the electromagnetic wave absorber of
Under such circumstances, electromagnetic wave absorbers that are easy to be incorporated into electronic devices and electronic components, have good electromagnetic wave absorption characteristics, are small, light, flexible, and are robust, are still satisfactory. There is no need.
上記状況に鑑み、本発明者らは、強磁性体の超微粒子分散を検討し、電磁波吸収特性に優れ、小型、軽量で可撓性があり、堅牢な電磁波吸収シートに到達した。
すなわち、本発明の電磁波吸収シートは、有機高分子と強磁性体からなる電磁波吸収機能層を有し、電磁波吸収機能層の総厚みあたりの電磁波最大透過減衰量が０．５〜５００ｄＢ／μｍであることを特徴とする。
又、本発明の熱伝導シート付き電磁波吸収シートは、前記電磁波吸収シートの少なくとも一方の面に、熱伝導性充填剤を含有する熱伝導シートを積層してなることを特徴とする。
また、本発明の電磁波吸収シートの製造方法は、有機高分子からなる基体（以下、有機高分子基体という。）上に、強磁性体粒子を粒子エネルギー５ｅＶ以上で物理的に蒸着して電磁波吸収機能層を形成することを特徴とする。
又、本発明の電子機器は前記電磁波吸収シートが電子部品あるいは電子部品群の少なくとも一部を覆ってなることを特徴とする。
又、本発明の電子機器は前記電磁波吸収シート、印刷回路板を有する電子機器の少なくとも一つの印刷回路板の少なくとも一方の面の一部又は全面に設けられてなることを特徴とする。
又、本発明の電子機器は前記電磁波吸収シートが、印刷回路板を有する電子機器の印刷回路に信号を伝達する電気コネクタに積層されていることを特徴とする。
又、本発明の電子機器は下面に前記電磁波吸収シートが積層された押釦スイッチ用キートップ部材を用いてなることを特徴とする。
又、本発明の電子機器はクリック部材を配列したクリックシートと、クリックシート上に設けられたキートップとを有し、クリックシートの一方の面に前記電磁波吸収シートが積層されてなる押釦スイッチ用キートップ部材を有することを特徴とする。
又、本発明の電子機器は少なくとも一方の面に前記電磁波吸収シートが積層されたプレフォーム用インサートシートを用いてなることを特徴とする。
In view of the above situation, the present inventors have studied dispersion of ultrafine particles of a ferromagnetic material, and have reached an electromagnetic wave absorbing sheet that is excellent in electromagnetic wave absorption characteristics, is small, lightweight, flexible, and robust.
That is, the electromagnetic wave absorbing sheet of the present invention has an electromagnetic wave absorbing functional layer composed of an organic polymer and a ferromagnetic material, and an electromagnetic wave maximum transmission attenuation per total thickness of the electromagnetic wave absorbing functional layer is 0.5 to 500 dB / μm. It is characterized by being.
The electromagnetic wave absorbing sheet with a heat conductive sheet of the present invention is characterized in that a heat conductive sheet containing a heat conductive filler is laminated on at least one surface of the electromagnetic wave absorbing sheet.
In addition, the method for producing an electromagnetic wave absorbing sheet of the present invention can absorb electromagnetic waves by physically depositing ferromagnetic particles on a substrate made of an organic polymer (hereinafter referred to as an organic polymer substrate) at a particle energy of 5 eV or more. A functional layer is formed.
The electronic device of the present invention is characterized in that the electromagnetic wave absorbing sheet covers at least a part of an electronic component or an electronic component group.
In addition, the electronic device of the present invention is characterized in that it is provided on a part or all of at least one surface of at least one printed circuit board of the electronic device having the electromagnetic wave absorbing sheet and the printed circuit board.
The electronic device according to the present invention is characterized in that the electromagnetic wave absorbing sheet is laminated on an electrical connector that transmits a signal to a printed circuit of an electronic device having a printed circuit board.
The electronic device of the present invention is characterized in that it uses a key top member for a pushbutton switch in which the electromagnetic wave absorbing sheet is laminated on the lower surface.
The electronic device of the present invention has a click sheet in which click members are arranged, and a key top provided on the click sheet, and is for a push button switch in which the electromagnetic wave absorbing sheet is laminated on one surface of the click sheet. It has a key top member.
The electronic device of the present invention is characterized by using a preform insert sheet in which the electromagnetic wave absorbing sheet is laminated on at least one surface.
本発明によれば、電磁波吸収特性が良く、小型、軽量で、可撓性があり、堅牢な電磁波吸収シートを提供することができる。 According to the present invention, it is possible to provide an electromagnetic wave absorbing sheet having good electromagnetic wave absorption characteristics, small size, light weight, flexibility and robustness.
本発明で用いられる強磁性体としては、金属系軟磁性体および／または、酸化物系軟磁性体および／または、窒化物系軟磁性体が主に用いられるが、これらは１種単独で用いてもよいし、これらの２種以上を混合して用いてもよい。
金属系軟磁性体としては、鉄および鉄合金が一般的に用いられ、鉄合金として具体的にはＦｅ−Ｎｉ、Ｆｅ−Ｃｏ、Ｆｅ−Ｃｒ、Ｆｅ−Ｓｉ、Ｆｅ−Ａｌ、Ｆｅ−Ｃｒ−Ｓｉ、Ｆｅ−Ｃｒ−Ａｌ及びＦｅ−Ａｌ−Ｓｉ合金を用いることができる。これらの金属系軟磁性体は１種単独で用いてもよいし、２種以上の組合せを用いてもよい。鉄および鉄合金のほかにコバルトやニッケルの金属あるいはそれらの合金を用いてもよい。ニッケルは単独で用いた場合は酸化に対して抵抗力があるので好ましい。
As the ferromagnetic material used in the present invention, metal-based soft magnetic materials and / or oxide-based soft magnetic materials and / or nitride-based soft magnetic materials are mainly used, but these are used alone. Alternatively, two or more of these may be mixed and used.
As the metal-based soft magnetic material, iron and an iron alloy are generally used. Specific examples of the iron alloy include Fe—Ni, Fe—Co, Fe—Cr, Fe—Si, Fe—Al, and Fe—Cr—. Si, Fe—Cr—Al, and Fe—Al—Si alloys can be used. These metallic soft magnetic materials may be used alone or in combinations of two or more. In addition to iron and iron alloys, cobalt or nickel metals or alloys thereof may be used. Nickel is preferred because it is resistant to oxidation when used alone.
酸化物系軟磁性体としてはフェライトが好ましい。具体的にはＭｎＦｅ２Ｏ４、ＣｏＦｅ２Ｏ４、ＮｉＦｅ２Ｏ４、ＣｕＦｅ２Ｏ４、ＺｎＦｅ２Ｏ４、ＭｇＦｅ２Ｏ４、Ｆｅ３Ｏ４、Ｃｕ−Ｚｎ−フェライト、Ｎｉ−Ｚｎ−フェライト、Ｍｎ−Ｚｎ−フェライト、Ｂａ２Ｃｏ２Ｆｅ１２Ｏ２２、Ｂａ２Ｎｉ２Ｆｅ１２Ｏ２２、Ｂａ２Ｚｎ２Ｆｅ１２Ｏ２２、Ｂａ２Ｍｎ２Ｆｅ１２Ｏ２２、Ｂａ２Ｍｇ２Ｆｅ１２Ｏ２２、Ｂａ２Ｃｕ２Ｆｅ１２Ｏ２２、Ｂａ３Ｃｏ２Ｆｅ２４Ｏ４１を用いることができる。これらのフェライトは１種単独で用いても良いし、２種以上を組合せて用いてもよい。
窒化物系軟磁性体としては、Ｆｅ２Ｎ、Ｆｅ３Ｎ、Ｆｅ４Ｎ、Ｆｅ１６Ｎ２などが知られている。これらの窒化物系軟磁性体は透磁率が高く、耐食性が高いので好ましい。
Ferrite is preferable as the oxide soft magnetic material. MnFe 2 O 4 Specifically, CoFe 2 O 4, NiFe 2 O 4, CuFe 2
Known nitride-based soft magnetic materials include Fe 2 N, Fe 3 N, Fe 4 N, and Fe 16 N 2 . These nitride-based soft magnetic materials are preferable because of their high magnetic permeability and high corrosion resistance.
有機高分子基体として用いられる有機高分子は、ポリオレフィン系樹脂、ポリアミド系樹脂、ポリエステル系樹脂、ポリエーテル系樹脂、ポリケトン系樹脂、ポリイミド系樹脂、ポリウレタン系樹脂、ポリシロキサン系樹脂、フェノール系樹脂、エポキシ系樹脂、アクリル系樹脂や、天然ゴム、イソプレンゴム、ブタジエンゴム、スチレンブタジエンゴムなどのジエン系ゴム、ブチルゴム、エチレンプロピレンゴム、ウレタンゴム、シリコーンゴムなどの非ジエン系ゴムなどが挙げられる。これらは熱可塑性であってもよく、熱硬化性であってもよく、その未硬化物であってもよい。また、該有機高分子は上述の樹脂、ゴムなどの変性物、混合物、共重合物であってもよい。 Organic polymers used as organic polymer substrates include polyolefin resins, polyamide resins, polyester resins, polyether resins, polyketone resins, polyimide resins, polyurethane resins, polysiloxane resins, phenolic resins, Examples thereof include epoxy resins, acrylic resins, diene rubbers such as natural rubber, isoprene rubber, butadiene rubber, and styrene butadiene rubber, and non-diene rubbers such as butyl rubber, ethylene propylene rubber, urethane rubber, and silicone rubber. These may be thermoplastic, may be thermosetting, or may be an uncured product thereof. The organic polymer may be a modified product such as the above-described resin or rubber, a mixture, or a copolymer.
図１に、有機高分子基体上に強磁性体が物理的に蒸着された状態の電磁波シートの模式図を示す。
本発明の電磁波吸収シートは、有機高分子基体（１）上に強磁性体（３）の超微粒子が物理的に蒸着されているが、基体である有機高分子基体（１）の表層から０．０３〜２０μｍの範囲にわたって強磁性体（３）の超微粒子が部分的に潜り込んで三次元的に分散し、均質膜を形成していない電磁波吸収機能層（２）を形成していることが好ましい。
すなわち、一般的には強磁性体（３）が有機高分子基体（１）の表面のみに蒸着されると、蒸着量が増えるにつれて強磁性体の連続層が形成されて、電磁波を反射しやすくなる。これに対して有機高分子基体（１）の表面近傍に強磁性体（３）の超微粒子が分散して０．０３〜２０μｍの厚みの電磁波吸収機能層（２）を形成していると、有機高分子内に分散した強磁性体（３）の超微粒子が連続層を形成し難くなり、電磁波の反射を生じせしめずに電磁波を吸収できるようになる。電磁波吸収機能層（２）の厚みを０．０３μｍ以上とすることにより、充分な電磁波吸収能を示すことができる。電磁波吸収機能層（２）を複数層積層して、その総厚みを１００μｍを超える厚みとしてもそれ以上の電磁波吸収機能の向上はなく、厚い電磁波吸収機能層（２）を形成するためには、例えば物理蒸着における粒子エネルギーを高める必要が生じ、物理蒸着コストがそれだけ高くなるので好ましくない。
FIG. 1 shows a schematic diagram of an electromagnetic wave sheet in a state where a ferromagnetic material is physically deposited on an organic polymer substrate.
In the electromagnetic wave absorbing sheet of the present invention, ultrafine particles of the ferromagnetic material (3) are physically deposited on the organic polymer substrate (1). The ultrafine particles of the ferromagnet (3) are partially submerged and dispersed three-dimensionally over a range of 0.03 to 20 μm to form an electromagnetic wave absorbing functional layer (2) that does not form a homogeneous film. preferable.
That is, generally, when the ferromagnetic material (3) is deposited only on the surface of the organic polymer substrate (1), a continuous layer of the ferromagnetic material is formed as the deposition amount increases, and it is easy to reflect electromagnetic waves. Become. On the other hand, when the ultrafine particles of the ferromagnetic material (3) are dispersed in the vicinity of the surface of the organic polymer substrate (1) to form the electromagnetic wave absorbing functional layer (2) having a thickness of 0.03 to 20 μm, The ultrafine particles of the ferromagnetic material (3) dispersed in the organic polymer are difficult to form a continuous layer, and can absorb electromagnetic waves without causing reflection of the electromagnetic waves. By setting the thickness of the electromagnetic wave absorbing functional layer (2) to 0.03 μm or more, sufficient electromagnetic wave absorbing ability can be exhibited. In order to form a thick electromagnetic wave absorption functional layer (2) without laminating the electromagnetic wave absorption functional layer (2) in a plurality of layers and increasing the total thickness to more than 100 μm, there is no further improvement in the electromagnetic wave absorption function. For example, it is necessary to increase the particle energy in physical vapor deposition, which is not preferable because the physical vapor deposition cost increases accordingly.
また、強磁性体（３）がミクロンオーダーの大きさである場合、大きな透過吸収率を得るために、大量かつ高密度に強磁性体を使用し、厚く重い電磁波吸収シートを用いる必要があるが、強磁性体（３）を例えばナノメーターオーダーまで超微粒子化すると、ミクロンオーダーの粒子の場合とは特性が異なり、透磁率が大きくなり、吸収帯域が拡がることが知られている。従って、大きな透過吸収率を得るために、上記の場合のように大量かつ高密度に強磁性体を使用し、厚く重い電磁波吸収シートを用いる必要がなくなる。 In addition, when the ferromagnetic material (3) has a size on the order of microns, it is necessary to use a large amount and a high density of ferromagnetic material and to use a thick and heavy electromagnetic wave absorbing sheet in order to obtain a large transmittance. It is known that when the ferromagnetic material (3) is made into ultrafine particles, for example, in the nanometer order, the characteristics are different from those in the case of micron order particles, the magnetic permeability is increased, and the absorption band is expanded. Therefore, in order to obtain a large transmission absorption rate, it is not necessary to use a large amount and a high density of ferromagnetic material and to use a thick and heavy electromagnetic wave absorbing sheet as in the above case.
この電磁波吸収機能層（２）中の強磁性体（３）の微粒子の寸法を直接測定するのは困難であるが、この強磁性体（３）がナノメーターオーダーの微粒子となっていることの目安として、電磁波吸収シートの電磁波吸収機能層（２）の厚みあたりの電磁波最大透過減衰量（ｄＢ／μｍ）で判断することができる。
電磁波吸収機能層（２）の厚みあたりの電磁波最大透過減衰量が、０．５〜５００ｄＢ／μｍであると、強磁性体（３）がナノメーターオーダーの微粒子になっていることを示す。本発明においては、この電磁波吸収機能層（２）の厚みあたりの電磁波最大透過減衰量が、０．５〜５００ｄＢ／μｍであることが必要である。この指標が０．５ｄＢ／μｍよりも小さいかあるいは５００ｄＢ／μｍよりも大きいと電磁波の吸収効率が悪く、電磁波が透過しやすくなり、電磁波吸収効果が無くなるか、あるいは所定の電磁波吸収効果を発現させるためには電磁波吸収シートの厚みを厚くする必要が生じ、使用する電子機器等のスペースの制限が生じてくる。
電磁波最大透過減衰量は、吸収したい周波数帯域で測定される最大の透過減衰量を指し、例えば１０ＭＨｚ〜１ＧＨｚ、１００ＭＨｚ〜３ＧＨｚ、１〜３ＧＨｚ、３〜２０ＧＨｚ、２０〜５０ＧＨｚ、５０〜１００ＧＨｚなどの帯域で周波数を変えながら電磁波吸収機能層を透過してくる電磁波量を測定し、最も透過減衰量が大きかった時の周波数における電磁波透過減衰量を意味する。
Although it is difficult to directly measure the size of the fine particles of the ferromagnet (3) in the electromagnetic wave absorption functional layer (2), the ferromagnet (3) is a nanometer-order microparticle. As a standard, it can be determined by the electromagnetic wave maximum transmission attenuation (dB / μm) per thickness of the electromagnetic wave absorbing functional layer (2) of the electromagnetic wave absorbing sheet.
When the electromagnetic wave maximum transmission attenuation amount per thickness of the electromagnetic wave absorbing functional layer (2) is 0.5 to 500 dB / μm, it indicates that the ferromagnetic material (3) is a nanometer order fine particle. In the present invention, the electromagnetic wave maximum transmission attenuation amount per thickness of the electromagnetic wave absorption functional layer (2) needs to be 0.5 to 500 dB / μm. If this index is smaller than 0.5 dB / μm or larger than 500 dB / μm, the electromagnetic wave absorption efficiency is poor and the electromagnetic wave is easily transmitted, and the electromagnetic wave absorbing effect is lost or a predetermined electromagnetic wave absorbing effect is exhibited. For this purpose, it is necessary to increase the thickness of the electromagnetic wave absorbing sheet, which limits the space of the electronic equipment to be used.
The electromagnetic wave maximum transmission attenuation amount indicates the maximum transmission attenuation amount measured in the frequency band to be absorbed, for example, 10 MHz to 1 GHz, 100 MHz to 3 GHz, 1 to 3 GHz, 3 to 20 GHz, 20 to 50 GHz, 50 to 100 GHz, and the like. The amount of electromagnetic wave transmitted through the electromagnetic wave absorbing functional layer while changing the frequency is measured, and the electromagnetic wave transmission attenuation amount at the frequency when the transmission attenuation amount is the largest.
電磁波吸収機能層の厚みに対しての電磁波透過量が小さくても、実使用上で実効的な値でなくてはならず、電磁波吸収の効果があるとされる６ｄＢ以上、ピーク値では１０ｄＢ以上である必要がある。吸収の効果として認められる上限は５０ｄＢであれば十分である。また、電磁波吸収機能層の厚みも、電子機器内に納まる適当な厚さである必要があり、０．０３〜１００μｍが好ましい。電磁波吸収シートとしては、この電磁波吸収機能層のほかに、支持層や粘着層あるいは絶縁層や保護層などを有するもので、各層は極力薄いことが好ましい。
同様に、吸収の効果を得るためには、電磁波の反射量も小さいことが好ましく、最大透過減衰量を示す帯域での反射減衰量が６ｄＢ以上であることが好ましく、１０ｄＢ以上がさらに好ましい。
Even if the electromagnetic wave transmission amount with respect to the thickness of the electromagnetic wave absorption functional layer is small, it must be an effective value in actual use, and is 6 dB or more, which is considered to have an electromagnetic wave absorption effect, and a peak value of 10 dB or more Need to be. The upper limit recognized as an effect of absorption is sufficient if it is 50 dB. Moreover, the thickness of the electromagnetic wave absorption functional layer needs to be an appropriate thickness that can be accommodated in the electronic device, and is preferably 0.03 to 100 μm. In addition to the electromagnetic wave absorbing functional layer, the electromagnetic wave absorbing sheet includes a support layer, an adhesive layer, an insulating layer, a protective layer, and the like, and each layer is preferably as thin as possible.
Similarly, in order to obtain an absorption effect, it is preferable that the reflection amount of the electromagnetic wave is small, the reflection attenuation amount in the band showing the maximum transmission attenuation amount is preferably 6 dB or more, and more preferably 10 dB or more.
電磁波吸収シートが電磁波吸収機能層の厚みあたりの高い透過減衰量を有するためには、物理蒸着にあたって、強磁性体超微粒子が有機高分子基体の表面から有機高分子基体内部に潜り込む必要があり、そのためには、該有機高分子の剪断弾性率が低いことが好ましい。有機高分子の剪断弾性率が低いと、有機高分子基体への強磁性体の物理的蒸着時に、強磁性体超微粒子が有機高分子基体内に侵入あるいは強磁性体超微粒子の衝突による有機高分子の変形や流動により、有機高分子基体表層の０．０３〜２０μｍの層にわたり分散しやすくなる。
図２ａは強磁性体を蒸着した有機高分子基体の表面状態を示すレーザー顕微鏡画像であり、表面には凹凸が見られる。図２ｂではその断面形状を計測しており、突起の高さは約６μｍである。一方、図３ａは蒸着前の表面状態を示すレーザー顕微鏡画像であるが、蒸着前の表面は平坦である。図３ｂではその断面形状を計測しており、平均表面粗さは０．０５μｍである。図２、図３から、蒸着により、有機高分子が変形や流動を起こしていることが伺われる。
以上の観点から、物理的蒸着時には、有機高分子の剪断弾性率が、１×１０３〜１×１０７Ｐａであることが好ましく、より好ましくは１×１０３〜１×１０６Ｐａ、さらに好ましくは１×１０３〜１×１０５Ｐａとされる。物理的蒸着時には、所望の剪断弾性率にするために必要ならば基体を例えば１００〜３００℃に加熱することもできるが、分解や蒸発が起きない温度に加熱することが必要である。常温で物理的蒸着を行う時には、特に加熱を必要とするものではないが、この常温で物理蒸着する対象となる有機高分子としては、おおよそゴム硬度５０〜６０°（ＪＩＳ−Ａ）以下の弾性体が挙げられる。
In order for the electromagnetic wave absorbing sheet to have a high transmission attenuation per thickness of the electromagnetic wave absorbing functional layer, it is necessary for the ferromagnetic ultrafine particles to enter the inside of the organic polymer substrate from the surface of the organic polymer substrate in physical vapor deposition. For this purpose, it is preferable that the organic polymer has a low shear modulus. When the shear modulus of the organic polymer is low, the ferromagnetic ultrafine particles penetrate into the organic polymer substrate or collide with the ferromagnetic ultrafine particles during the physical vapor deposition of the ferromagnetic material on the organic polymer substrate. Due to the deformation and flow of the molecule, it becomes easy to disperse over the 0.03 to 20 μm layer of the surface of the organic polymer substrate.
FIG. 2a is a laser microscope image showing the surface state of an organic polymer substrate on which a ferromagnetic material is deposited, and irregularities are seen on the surface. In FIG. 2b, the cross-sectional shape is measured, and the height of the protrusion is about 6 μm. On the other hand, FIG. 3a is a laser microscope image showing the surface state before vapor deposition, but the surface before vapor deposition is flat. In FIG. 3b, the cross-sectional shape is measured, and the average surface roughness is 0.05 μm. 2 and 3, it can be seen that the organic polymer is deformed or fluidized by vapor deposition.
From the above viewpoints, at the time of physical vapor deposition, the shear modulus of the organic polymer is preferably 1 × 10 3 to 1 × 10 7 Pa, more preferably 1 × 10 3 to 1 × 10 6 Pa, and further Preferably, it is 1 × 10 3 to 1 × 10 5 Pa. During physical vapor deposition, the substrate can be heated to, for example, 100 to 300 ° C. if necessary in order to obtain a desired shear modulus, but it is necessary to heat to a temperature at which decomposition and evaporation do not occur. When physical vapor deposition is performed at normal temperature, heating is not particularly required. However, as an organic polymer to be physically vapor-deposited at normal temperature, the elasticity of rubber hardness is about 50 to 60 ° (JIS-A) or less. The body is mentioned.
また、プラズマ化あるいはイオン化された強磁性体原子が入り込みやすい分子間空隙の広さを示す指標として、ガス透過率を用いることができる。本来は、前記した強磁性体元素の大きさに等しいアルゴンガス、クリプトンガスが透過率を確認することに都合がよいが、ガス透過率の測定には一般的でないため、例えば炭酸ガスの透過率データで代用することができる。常温での炭酸ガス透過率の大きな有機高分子として、１×１０−９［ｃｍ３（ＳＴＰ）ｃｍ／（ｃｍ２×ｓ×ｃｍＨｇ）］以上のポリフェニレンオキサイド、ポリメチルペンテン、ナイロン１１、ハイインパクトポリスチレンなどのゴム成分との混合物や共重合物、１×１０−８［ｃｍ３（ＳＴＰ）ｃｍ／（ｃｍ２×ｓ×ｃｍＨｇ）］以上のポリブタジエン、ポリイソプレン、スチレンブタジエンゴム、シリコーンゴムなどが挙げられる。剪断弾性率の点からもシリコーンゴムなどのゴム類は特に好ましい。 In addition, gas permeability can be used as an index indicating the size of intermolecular voids where plasmad or ionized ferromagnetic atoms can easily enter. Originally, argon gas and krypton gas, which are equal in size to the ferromagnetic elements described above, are convenient for confirming the transmittance, but are not generally used for measuring the gas permeability. Data can be substituted. As an organic polymer having a large carbon dioxide gas permeability at room temperature, polyphenylene oxide, polymethylpentene, nylon 11, high impact of 1 × 10 −9 [cm 3 (STP) cm / (cm 2 × s × cmHg)] or more Polybutadiene, polyisoprene, styrene butadiene rubber, silicone rubber, etc. with a mixture or copolymer with a rubber component such as polystyrene, 1 × 10 −8 [cm 3 (STP) cm / (cm 2 × s × cmHg)] or more Can be mentioned. From the viewpoint of shear modulus, rubbers such as silicone rubber are particularly preferable.
また、強磁性体超微粒子の酸化を防止する観点からは、酸素透過性の低いものが良く、１×１０−１０［ｃｍ３（ＳＴＰ）ｃｍ／（ｃｍ２×ｓ×ｃｍＨｇ）］以下のポリエチレン、ポリトリフルオロクロロエチレン、ポリメチルメタクリレートなどやさらには１×１０−１２［ｃｍ３（ＳＴＰ）ｃｍ／（ｃｍ２×ｓ×ｃｍＨｇ）］以下のポリエチレンテレフタレート、ポリアクリロニトリルなどを挙げることができる。 In addition, from the viewpoint of preventing the oxidation of the ferromagnetic ultrafine particles, those having low oxygen permeability are preferable, and polyethylene having a density of 1 × 10 −10 [cm 3 (STP) cm / (cm 2 × s × cmHg)] or less. , Polytrifluorochloroethylene, polymethyl methacrylate, and the like, and polyethylene terephthalate, polyacrylonitrile, and the like of 1 × 10 −12 [cm 3 (STP) cm / (cm 2 × s × cmHg)] or less.
このほか、補強性フィラーや難燃剤、老化防止剤、酸化防止剤、着色剤、チクソトロピー性向上剤、可塑剤、滑剤、耐熱向上剤などを適宜添加して構わないが、硬質なものを配合すると、強磁性超微粒子がこれに衝突し、十分な分散が行われないことがあるので、注意が必要である。 In addition, reinforcing fillers, flame retardants, antioxidants, antioxidants, colorants, thixotropic improvers, plasticizers, lubricants, heat improvers, etc. may be added as appropriate, Care must be taken because the ultrafine ferromagnetic particles may collide with this and may not be sufficiently dispersed.
該有機高分子の膜厚は薄い方がよく、１〜２００μｍ程度とされる。有機高分子の膜が単独では薄くて、あるいは使用温度域での剪断弾性率が小さくて、ハンドリングが困難な場合は、別に該有機高分子を担持する支持層を設けることができる。支持層は前記した高分子基体と同等のものであってもよいが、金属箔や可撓性のあるセラミックス箔などで、有機高分子基体を構成する有機高分子より剛性が高く、剪断弾性率の高いものがよい。その支持層の厚さは薄いものがよく、５０μｍ以下が好ましく、２５μｍ以下がさらに好ましい。
有機高分子基体や、支持体を構成する薄い有機高分子の膜を形成するには、製膜材料の流動性の大きいことがよく、有機高分子を溶剤に溶解した溶液を製膜してもよく、有機高分子が単独で流動性を有する場合は無溶剤で製膜してもよい。
The film thickness of the organic polymer is preferably thin, and is about 1 to 200 μm. When the organic polymer film is thin by itself or has a low shear modulus in the operating temperature range and is difficult to handle, a separate supporting layer for supporting the organic polymer can be provided. The support layer may be the same as the polymer substrate described above, but it is a metal foil or a flexible ceramic foil, which has higher rigidity and higher shear modulus than the organic polymer constituting the organic polymer substrate. Higher ones are better. The thickness of the support layer is preferably small, preferably 50 μm or less, and more preferably 25 μm or less.
In order to form an organic polymer substrate or a thin organic polymer film constituting the support, the fluidity of the film-forming material is good, and even if a solution obtained by dissolving the organic polymer in a solvent is formed If the organic polymer has fluidity alone, it may be formed without a solvent.
図４に強磁性体が物理的に蒸着された有機高分子の断面状態のＳＥＭ像を示す。これは、前記した表面の突起状部を除く、ベース部分の断面を観察したものであり、約４５質量％の湿式シリカなどの無機フィラーを含む弾性体に、３０ｎｍ厚相当の強磁性体を蒸着することにより、表層のスキン層に４０ｎｍ厚の電磁波吸収機能層が形成されている。このように強磁性体が、直接、超微粒子化された状態で、電磁波吸収機能層に分散されているため、再加熱等による強磁性体の再結晶をはかるなどの後処理の必要がない。 FIG. 4 shows an SEM image of a cross-sectional state of an organic polymer on which a ferromagnetic material is physically deposited. This is the result of observing the cross section of the base portion excluding the protrusions on the surface described above, and depositing a ferromagnetic material equivalent to a thickness of 30 nm on an elastic material containing an inorganic filler such as about 45 mass% wet silica. Thus, an electromagnetic wave absorption functional layer having a thickness of 40 nm is formed on the skin layer of the surface layer. As described above, since the ferromagnetic material is directly dispersed in the electromagnetic wave absorption functional layer in the form of ultrafine particles, there is no need for post-treatment such as recrystallization of the ferromagnetic material by reheating or the like.
強磁性体として、特に鉄、ニッケル、コバルトなどやその合金などの金属系軟磁性体を用いた場合、金属系軟磁性体が凝集して均質膜を形成するように蒸着されていると、金属系軟磁性体の固有抵抗が小さいので、渦電流が発生して電磁波吸収効果がなくなり、むしろ反射機能がでてくるため、電子回路や電子部品からの電磁波を吸収できずに、反射してしまい、電子回路等に逆に影響を与えてしまう。したがって、金属系軟磁性体を有機高分子基体（１）上に物理的に蒸着する場合は、特に、均質な強磁性体膜を形成しないようにすることがよい。膜の表面抵抗（直流抵抗）はおおよそ１×１０１〜１×１０１０Ω／□であることが好ましい。
後述する物理蒸着法により原子状態になった強磁性体元素は、おおよそ数Åのサイズであるが、有機高分子は、金属やセラミックスと異なり分子間に空隙を有しており、飛ばされた強磁性体原子は、この空隙に入り込み微小なクラスターや非常に薄い薄膜粒子を形成すると考えられるが、一平面に堆積して連続した薄膜を形成することがなく、三次元的に分散するため、蒸着量が少ない場合は、容易に超微粒子が独立して、良導通を示さない状態になり易い。
さらに、強磁性体の超微粒子が有機高分子基体の内部に深く入り込むことが可能になると、一度の蒸着で蒸着量が多くても容易に分散し、均質膜となることがないので、加工時間の手間を省くことができる。
When a metallic soft magnetic material such as iron, nickel, cobalt, or an alloy thereof is used as the ferromagnetic material, if the metallic soft magnetic material is deposited so as to aggregate and form a homogeneous film, the metal Since the resistivity of the soft magnetic material is small, eddy currents are generated and the effect of absorbing electromagnetic waves is lost. Instead, the reflection function appears, so that electromagnetic waves from electronic circuits and electronic components cannot be absorbed and reflected. This adversely affects electronic circuits and the like. Therefore, when a metal soft magnetic material is physically vapor-deposited on the organic polymer substrate (1), it is particularly preferable not to form a homogeneous ferromagnetic film. The surface resistance (DC resistance) of the film is preferably about 1 × 10 1 to 1 × 10 10 Ω / □.
Ferromagnetic elements that have been in an atomic state by physical vapor deposition, which will be described later, are approximately several tens of a size in size, but organic polymers, unlike metals and ceramics, have voids between the molecules, and have been blown off. It is thought that magnetic atoms enter the voids and form minute clusters and very thin thin film particles, but they are deposited in one plane and do not form a continuous thin film, but are dispersed three-dimensionally. When the amount is small, the ultrafine particles easily become independent and do not show good conduction.
Furthermore, if the ultrafine particles of the ferromagnetic material can penetrate deeply into the organic polymer substrate, even if the amount of deposition is large in one deposition, it is easily dispersed and does not become a homogeneous film. Can be saved.
物理蒸着法（ＰＶＤ）での各種成膜方法は、真空にした容器の中で薄膜形成物質を何らかの方法で気化させ、近傍に置いた基板上に堆積させて薄膜を形成する方法である。
物理蒸着法を薄膜物質の気化方法で分類すると、蒸発系とスパッタ系に分けられ、蒸発系にはＥＢ蒸着、イオンプレーティング、スパッタ系にはマグネトロンスパッタリング、対向ターゲット型マグネトロンスパッタリングなどが挙げられる。
Various film forming methods by physical vapor deposition (PVD) are methods in which a thin film forming material is vaporized by some method in a vacuumed container and deposited on a substrate placed in the vicinity to form a thin film.
The physical vapor deposition method is classified into a vaporization method of a thin film material, and is divided into an evaporation system and a sputtering system. Examples of the evaporation system include EB vapor deposition, ion plating, and sputtering system includes magnetron sputtering and counter target type magnetron sputtering.
ＥＢ蒸着は、蒸発粒子のエネルギーが１ｅＶと小さいので、基板のダメージが少なく、膜がポーラスになりやすく、膜強度が不足する傾向があるが、強磁性体膜の固有抵抗は高くなるという特徴がある。
イオンプレーティングはアルゴンガスや蒸発粒子のイオンは加速されて基板に衝突するため、ＥＢよりエネルギーは大きく、付着力の強い膜を得ることができる。ドロップレットと呼んでいるミクロンサイズの粒子が多数付着してしまうと放電が停止してしまう。また、酸化物系強磁性体を成膜するには、酸素などの反応性ガスを導入しなければならず、膜質コントロールが難しい反面、バイアス電圧を上げることにより１ＫｅＶまで原子状超微粒子を加速させることができる。
通常のマグネトロンスパッタリングは、磁界の影響で強いプラズマが発生するため成長速度が速い特徴があるが、ターゲットの利用効率が低い。バイアスを掛けた場合は数百ｅＶまでエネルギーをあげることができる。
マグネトロンスパッタリングのうち対向ターゲット型マグネトロンスパッタリングは、対向するターゲット間でプラズマを発生させ、対向するターゲットの外に基板を置き、プラズマダメージを受けることなく所望の薄膜を生成する方法である。そのため、基板上の薄膜を再スパッタすることなく、成長速度がさらに速く、スパッタされた原子が衝突緩和することがなく、緻密なターゲット組成物と同じ組成のものを生成することができ、通常８ｅＶ以上の高いエネルギーを持っている。
EB deposition has a feature that the energy of evaporated particles is as small as 1 eV, so that the substrate is less damaged, the film tends to be porous, and the film strength tends to be insufficient, but the specific resistance of the ferromagnetic film is increased. is there.
In the ion plating, ions of argon gas and evaporated particles are accelerated and collide with the substrate, so that a film having higher energy and stronger adhesion than EB can be obtained. If a large number of micron-sized particles called droplets adhere, the discharge stops. In addition, in order to form an oxide-based ferromagnetic material, a reactive gas such as oxygen must be introduced, and while it is difficult to control the film quality, the atomic ultrafine particles are accelerated to 1 KeV by increasing the bias voltage. be able to.
Ordinary magnetron sputtering is characterized by a high growth rate because strong plasma is generated under the influence of a magnetic field, but the target utilization efficiency is low. When a bias is applied, the energy can be increased up to several hundred eV.
Opposite target type magnetron sputtering is a method of generating a desired thin film without being damaged by plasma by generating plasma between opposing targets and placing a substrate outside the opposing targets. Therefore, without re-sputtering the thin film on the substrate, the growth rate is higher, the sputtered atoms are not impact-relaxed, and a dense target composition having the same composition can be generated, usually 8 eV. Has higher energy.
代表的な有機の共有結合エネルギーは約４ｅＶであり、具体的には例えばＣ−Ｃ、Ｃ−Ｈ、Ｓｉ−Ｏ、Ｓｉ−Ｃの結合エネルギーはそれぞれ３．６、４．３、４．６、３．３ｅＶであるのに対して、バイアスイオンプレーティング、バイアスマグネトロンスパッタや対向ターゲット型マグネトロンスパッタでは、このように高いエネルギーを持っているので、一部の化学結合を切断し、衝突するものであるから、スパッタ後の基体表面には例えば５μｍ以上の凹凸が形成され、強磁性体原子が、有機高分子基体の表面からおおよそ０．０３〜２０μｍ程度まで進入し、電磁波吸収機能層を形成することができる。これは、高エネルギーの強磁性体原子の基体表面への衝突等により強磁性体原子と有機高分子の局部的なミキシング作用が生じたためと推測される。このように、粒子エネルギーが５ｅＶ以上である強磁性体微粒子を有機高分子基体上に物理的に蒸着すると、一度に大量の強磁性体を分散させることができるので好ましい。すなわち、一度の蒸着で、強磁性体の質量を稼ぐことができることから、透過吸収率の大きな吸収体を容易に得ることができるため、好ましい。 A typical organic covalent bond energy is about 4 eV. Specifically, for example, the bond energies of C—C, C—H, Si—O, and Si—C are 3.6, 4.3, and 4.6, respectively. In contrast to 3.3 eV, bias ion plating, bias magnetron sputtering, and opposed target type magnetron sputtering have such high energy, so that some chemical bonds are broken and collide with each other. Therefore, irregularities of 5 μm or more, for example, are formed on the surface of the substrate after sputtering, and ferromagnetic atoms enter from the surface of the organic polymer substrate to about 0.03 to 20 μm to form an electromagnetic wave absorption functional layer. can do. This is presumably because a local mixing action of the ferromagnetic atoms and the organic polymer was caused by collision of the high energy ferromagnetic atoms with the substrate surface. Thus, it is preferable to physically deposit the ferromagnetic fine particles having a particle energy of 5 eV or more on the organic polymer substrate because a large amount of the ferromagnetic material can be dispersed at one time. That is, it is preferable because the mass of the ferromagnetic material can be increased by a single vapor deposition, and thus an absorber having a large transmittance can be easily obtained.
強磁性体の蒸着質量は、強磁性体単品の膜厚換算値で２００ｎｍ以下が好ましく、これより厚いと高分子基体の包含能力の限界に達し、分散できずに堆積し、均質な導通性を有する連続した膜が生成してしまう。それゆえ、より好ましくは１００ｎｍ以下、さらに好ましくは５０ｎｍ以下がよい。一方、電磁波吸収能の点からは０．５ｎｍ以上であることが好ましい。この蒸着質量は、ガラス、シリコン等の硬質基板上に堆積した厚みを測定することによって求められる。
蒸着された強磁性体は、電磁波吸収機能層中に分散されており、該機能層の厚みは、強磁性体単品の膜厚換算値よりも厚くなる。その測定は前記したように、断面のＳＥＭ像から算出することができる。
しかし、蒸着質量が小さくなると、吸収能力が低減するものであるから、電磁波吸収機能層を複数層積層して積層電磁波吸収シートとすることにより、適宜、電磁波吸収シートに占める強磁性体の総質量を増やすことが好ましい。この総質量は吸収レベルにもよるが、おおよそ総合の膜厚換算値で１０〜５００ｎｍがよい。電磁波吸収機能層の厚みは積層された各層の和とすることができ、１０〜１００μｍが好ましい。
積層電磁波吸収シートにおいては、その積層数は特に限定されるものではないが、積層電磁波吸収シートの全体の厚みを考慮して決められる。物理的蒸着後の、複数積層した有機高分子基体を含む全体の厚みは、おおよそ２０〜２００μｍ程度となるのが好ましい。そのため、有機高分子基体の厚みも積層電磁波吸収シートにした時の全体の厚みを考慮して適宜選択することが好ましい。
The vapor deposition mass of the ferromagnetic material is preferably 200 nm or less in terms of the film thickness of the single ferromagnetic material, and if it is thicker than this, the inclusion capacity of the polymer substrate is reached, it is deposited without being dispersed, and homogeneous conductivity is obtained. The continuous film | membrane which has is produced | generated. Therefore, 100 nm or less is more preferable, and 50 nm or less is more preferable. On the other hand, it is preferable that it is 0.5 nm or more from the point of electromagnetic wave absorptivity. This vapor deposition mass can be obtained by measuring the thickness deposited on a hard substrate such as glass or silicon.
The deposited ferromagnetic material is dispersed in the electromagnetic wave absorbing functional layer, and the thickness of the functional layer is larger than the film thickness converted value of the single ferromagnetic material. The measurement can be calculated from the SEM image of the cross section as described above.
However, since the absorption capacity is reduced when the deposition mass is reduced, the total mass of the ferromagnetic material in the electromagnetic wave absorbing sheet is appropriately obtained by laminating a plurality of electromagnetic wave absorbing functional layers into a laminated electromagnetic wave absorbing sheet. Is preferably increased. Although this total mass depends on the absorption level, it is preferably about 10 to 500 nm in terms of an overall film thickness conversion value. The thickness of the electromagnetic wave absorbing functional layer can be the sum of the laminated layers, and is preferably 10 to 100 μm.
In the laminated electromagnetic wave absorbing sheet, the number of laminated layers is not particularly limited, but is determined in consideration of the entire thickness of the laminated electromagnetic wave absorbing sheet. The total thickness including a plurality of stacked organic polymer substrates after physical vapor deposition is preferably about 20 to 200 μm. Therefore, it is preferable that the thickness of the organic polymer substrate is appropriately selected in consideration of the entire thickness when the laminated electromagnetic wave absorbing sheet is formed.
また、積層電磁波吸収シートにおいては、電磁波吸収機能層の厚みを変えたり、機能層中の強磁性体の質量を変えてもよい。例えば、電磁波吸収能力があるといえども、ある程度の反射が起こり、電磁波を放射した電子回路や電子部品に影響を与えることがあるので、積層する各電磁波吸収機能層の強磁性体の質量を、電子部品側の層から徐々に増して、傾斜的に配置するなど、極力反射を抑えることも可能である。 In the laminated electromagnetic wave absorbing sheet, the thickness of the electromagnetic wave absorbing functional layer may be changed, or the mass of the ferromagnetic material in the functional layer may be changed. For example, even if there is electromagnetic wave absorption capability, some reflection occurs, and it may affect electronic circuits and electronic components that radiate electromagnetic waves, so the mass of the ferromagnetic material of each electromagnetic wave absorption functional layer to be laminated, It is also possible to suppress reflection as much as possible, such as gradually increasing from the layer on the electronic component side and arranging it in an inclined manner.
本発明の熱伝導シート付き電磁波吸収シートに用いられる熱伝導シートは熱伝導性充填剤を含有するシートであり、熱伝導性充填剤としては、銅やアルミニウム等の金属、アルミニウムやインジウムなどの低融点合金、アルミナ、シリカ、マグネシア、ベンガラ、ベリリア、チタニア等の金属酸化物、窒化アルミニウム、窒化ケイ素、窒化ホウ素等の金属窒化物、或いは炭化ケイ素などを用いることができるが、特にこれらに限定されるものではない。 The heat conductive sheet used for the electromagnetic wave absorbing sheet with the heat conductive sheet of the present invention is a sheet containing a heat conductive filler. As the heat conductive filler, a metal such as copper or aluminum, or a low metal such as aluminum or indium is used. Melting point alloys, metal oxides such as alumina, silica, magnesia, bengara, beryllia, titania, metal nitrides such as aluminum nitride, silicon nitride, boron nitride, or silicon carbide can be used, but are not limited to these. It is not something.
熱伝導性充填剤の平均粒子径は０．１〜１００μｍであることが好ましく、１〜５０μｍであることがより好ましい。
粒径が０．１μｍ未満の場合には、粒子の比表面積が大きくなりすぎて高充填化が困難となる。粒径が１００μｍを超える場合には、熱伝導シートの表面に微小な凹凸が現れ、熱的な接触抵抗が大きくなるおそれがある。
熱伝導性充填剤の含有量は充填剤の種類にもよるが、１０〜８５ｖｏｌ％とすることが好ましい。１０ｖｏｌ％未満では、必要とする熱伝導性が得られない場合があり、８５ｖｏｌ％を超えると、シートが非常に脆いものとなってしまうおそれがある。
熱伝導シートを構成するシートの材質は特に限定されるものではないが、耐熱性、耐候性等の点からシリコーンゴム、ウレタンゴム等が好ましく用いられる。
この熱伝導シート付き電磁波吸収シートは、パワートランジスタやサイリスタのような発熱性半導体の放熱用途に特に効果がある。
The average particle size of the heat conductive filler is preferably 0.1 to 100 μm, and more preferably 1 to 50 μm.
When the particle size is less than 0.1 μm, the specific surface area of the particles becomes too large, making it difficult to achieve high packing. When the particle diameter exceeds 100 μm, minute irregularities appear on the surface of the heat conductive sheet, which may increase the thermal contact resistance.
Although content of a heat conductive filler is based also on the kind of filler, it is preferable to set it as 10-85 vol%. If it is less than 10 vol%, the required thermal conductivity may not be obtained, and if it exceeds 85 vol%, the sheet may be very brittle.
Although the material of the sheet | seat which comprises a heat conductive sheet is not specifically limited, Silicone rubber, urethane rubber, etc. are used preferably from points, such as heat resistance and a weather resistance.
This electromagnetic wave absorbing sheet with a heat conductive sheet is particularly effective for heat dissipation of heat-generating semiconductors such as power transistors and thyristors.
本発明の電磁波吸収シートは種々の電子機器の電子部品から発生する電磁波を吸収して電磁波による悪影響を抑制することができる。即ち電子機器が有する電子部品の中、他からの電磁波により誤作動を起こすおそれのある電子部品や電磁波を発生して他の電子部品に誤作動を起こすおそれのある電子部品を本発明の電磁波吸収体で覆って、電子部品から発生する、あるいは電子部品に影響を与えようとする電磁波を吸収することができる。このような電子機器としては、信号を発信、受信あるいは受発信する機器であればどのような電子機器も対象となる。即ち、本発明の電子機器は、該電子機器の有する電子部品あるいは電子部品群の少なくとも一部を上記電磁波吸収シートで覆ってなることを特徴とする。 The electromagnetic wave absorbing sheet of the present invention can absorb electromagnetic waves generated from electronic parts of various electronic devices and suppress adverse effects due to the electromagnetic waves. That is, among the electronic parts of electronic devices, the electronic parts that may cause malfunction due to electromagnetic waves from other parts and the electronic parts that may cause malfunctions due to the generation of electromagnetic waves may be absorbed by the electromagnetic wave according to the present invention. It can be covered with a body to absorb electromagnetic waves generated from or affecting electronic components. As such an electronic device, any electronic device can be used as long as it transmits, receives, or receives and transmits signals. That is, the electronic device of the present invention is characterized in that at least a part of an electronic component or a group of electronic components included in the electronic device is covered with the electromagnetic wave absorbing sheet.
本発明の電子機器は、上記電磁波吸収シートが、印刷回路板を有する電子機器の少なくとも一つの印刷回路板の少なくとも一方の面の一部又は全面に設けられてなることを特徴とする。
即ち、印刷回路板の両面全体、あるいは片面全体を覆っていてもよく、両面あるいは片面の一部を覆っていてもよい。印刷回路板上に設けられている電子部品から発生する電磁波が同じ印刷回路板上の他の電子部品に悪影響を与えるものでなければ、全体を電磁波吸収体で覆って、外部からの電磁波を吸収してもよい。
又、印刷回路板上の電子部品から発生する電磁波が同じ印刷回路板上の他の電子部品に悪影響を与えるものであれば、その悪影響を与える電磁波を発生する電子部品以外を例えばシールドボックスあるいは電磁波吸収シートで覆って、かつ、その悪影響を与える電磁波を発生する電子部品を個別に電磁波吸収シートで覆ってもよい。
本発明の電磁波吸収シートは可撓性を有するため、上記印刷回路板がフレキシブル印刷回路板である場合に、印刷回路板が応力により変形しても印刷回路板の変形に容易に追従してしっかりと電子部品を覆うことができるので特に適している。
The electronic device of the present invention is characterized in that the electromagnetic wave absorbing sheet is provided on a part or the whole of at least one surface of at least one printed circuit board of an electronic device having a printed circuit board.
That is, the entire printed circuit board may be covered on both sides or on one side, or both sides or part of one side may be covered. If the electromagnetic waves generated from the electronic components provided on the printed circuit board do not adversely affect other electronic components on the same printed circuit board, cover the whole with an electromagnetic wave absorber to absorb external electromagnetic waves. May be.
In addition, if the electromagnetic waves generated from the electronic components on the printed circuit board adversely affect other electronic components on the same printed circuit board, other than the electronic components that generate the adverse electromagnetic waves, for example, a shield box or electromagnetic waves An electronic component that covers an absorption sheet and generates an electromagnetic wave that adversely affects it may be individually covered with the electromagnetic wave absorption sheet.
Since the electromagnetic wave absorbing sheet of the present invention is flexible, when the printed circuit board is a flexible printed circuit board, even if the printed circuit board is deformed by stress, it easily follows the deformation of the printed circuit board. It is particularly suitable because it can cover electronic parts.
又、本発明の電子機器が少なくとも印刷回路板と印刷回路に信号を伝達する電気コネクタとを有するものであって、前記電磁波吸収シートが、該電気コネクタの少なくとも一部に積層されていると、電気コネクタに及ぼす外部からの電磁波による誤作動を惹き起こす信号の侵入を防止できる。この場合も本発明の電磁波吸収シートは可撓性を有するため、電気コネクタがフレキシブルコネクタであると、外部応力によりフレキシブルコネクタが変形してもその変形に容易に追従してしっかりとフレキシブルコネクタを覆うことができるので特に適している。
上記のような電子機器の例として携帯電話機、カメラ付き携帯電話機等を例示できる。
Further, the electronic device of the present invention has at least a printed circuit board and an electrical connector for transmitting a signal to the printed circuit, and the electromagnetic wave absorbing sheet is laminated on at least a part of the electrical connector. It is possible to prevent an intrusion of a signal that causes a malfunction due to an electromagnetic wave from the outside exerted on the electrical connector. Also in this case, since the electromagnetic wave absorbing sheet of the present invention has flexibility, if the electrical connector is a flexible connector, even if the flexible connector is deformed due to external stress, it easily follows the deformation and firmly covers the flexible connector. It is particularly suitable because it can.
Examples of the electronic device as described above include a mobile phone, a camera-equipped mobile phone, and the like.
又、本発明の電子機器としては、下面に前記電磁波吸収シートが積層された押釦スイッチ用キートップ部材を用いた電磁波ノイズ抑制電子機器を挙げることができ、このような押釦スイッチ用キートップ部材の具体例としては、押圧部を設けた加飾シートの下面に前記電磁波吸収シートが積層されてなる押釦スイッチ用キートップ部材を挙げることができる。
前記加飾シートの材料としては、ポリエステル、ポリウレタン、ポリカーボネート、アクリル、塩化ビニル、ポリエチレン、ポリプロピレンなど熱可塑性の樹脂が選択されるが、印刷性や成形加工性等を考慮するとポリエステル、ポリカーボネート、アクリル及びそれらのアロイ、共重合物が好ましい。
この加飾シートは必要に応じてシートの所定の位置に文字、記号、絵柄等の必要な印刷を施しておくことができる。この印刷は従来ある印刷方法を用いればよく、特に限定されるものではない。さらには塗装、メッキ、蒸着、ホットスタンプ、レーザーマーキング等の手法を用いて装飾を行っておいてもよい。
Moreover, the electronic device of the present invention can include an electromagnetic noise suppression electronic device using a key top member for a pushbutton switch in which the electromagnetic wave absorbing sheet is laminated on the lower surface. As a specific example, a key top member for a push button switch in which the electromagnetic wave absorbing sheet is laminated on a lower surface of a decorative sheet provided with a pressing portion can be exemplified.
As a material for the decorative sheet, a thermoplastic resin such as polyester, polyurethane, polycarbonate, acrylic, vinyl chloride, polyethylene, and polypropylene is selected. However, in consideration of printability and molding processability, polyester, polycarbonate, acrylic and Those alloys and copolymers are preferred.
This decorative sheet can be printed with necessary characters, symbols, patterns, etc. at predetermined positions on the sheet as required. This printing may be performed using a conventional printing method and is not particularly limited. Furthermore, the decoration may be performed using a technique such as painting, plating, vapor deposition, hot stamping, laser marking, or the like.
前記押圧部は加飾シートに絞り加工などにより凹部を設け、その凹部に樹脂、エラストマ等を充填してもよく、平板状の加飾シートの一方の面に樹脂、エラストマ等からなる押釦スイッチ状の成型体を接着してもよい。
加飾シートの凹部に充填されるあるいは加飾シート上に設けられる樹脂またはエラストマとしては、特に限定されるものではない。
電磁波吸収シートは押圧部を設けた加飾シートの下面に積層される。加飾シートに設けられた凹部に樹脂、エラストマ等を充填したものの場合は、凹部に充填された樹脂エラストマ等の底面と、加飾シートの凹部を有する側の面を共に覆う様に電磁波吸収シートが積層される。
加飾シート上に押釦スイッチ状の成型体が設けられたものの場合は加飾シートが設けられた面とは反対側の面に電磁波吸収シートが積層される。
The pressing portion may be provided with a recess in the decorative sheet by drawing or the like, and the recess may be filled with resin, elastomer, or the like, and a pushbutton switch made of resin, elastomer or the like on one surface of the flat decorative sheet The molded body may be adhered.
There is no particular limitation on the resin or elastomer filled in the concave portion of the decorative sheet or provided on the decorative sheet.
The electromagnetic wave absorbing sheet is laminated on the lower surface of the decorative sheet provided with the pressing portion. In the case where the concave portion provided in the decorative sheet is filled with resin, elastomer, etc., the electromagnetic wave absorbing sheet covers both the bottom surface of the resin elastomer filled in the concave portion and the surface of the decorative sheet having the concave portion. Are stacked.
In the case where a push button switch-like molded body is provided on the decorative sheet, the electromagnetic wave absorbing sheet is laminated on the surface opposite to the surface on which the decorative sheet is provided.
又、本発明の電子機器としては、クリック部材を配列したクリックシートと、クリックシート上に設けられたキートップとを有し、クリックシートの一方の面に前記電磁波吸収シートが積層されてなる押釦スイッチ用キートップ部材を有する電子機器を挙げることができる。
このような押釦スイッチ用キートップ部材の具体例としては、クリック部材が上に凸のドーム状で、ドーム状クリック部材内面（クリックシート下面）の少なくとも上部に導電性の被膜からなる可動接点が設けられ、キートップを押圧したときにクリック部材が変形して、例えばその下に配置された印刷配線基板上の固定接点に接触可能となっているものを挙げることができる。
電磁波吸収シートはクリックシートのキートップ側の面に積層されていてもよく、キートップ側と反対側の面に積層されていてもよい。キートップ側と反対側の面に積層されている場合は、電磁波吸収シートは前記可動接点と電気的に絶縁状態にある様に設けられる。即ち、可動接点のある部分を除いたクリックシート表面に電磁波吸収シートが積層されていてもよく、クリックシート下面の全面に電磁波吸収シートが積層され、電磁波吸収シートの表面のうち、ドーム状クリック部材内面の少なくとも上部に絶縁被膜を介して可動接点を設けてもよい。電磁波吸収シートが可動接点と電気的に絶縁されていると、キースキャンの際に他のキーとの干渉を抑制することができる。電磁波吸収シートがドーム状クリック部材の一方の面全面にわたって設けられているとミリ波帯域での電磁波の漏れを防止することができる。
クリックシートは押圧による変形性、押圧力解除時の反発による復元性、成型性等の点から例えばポリエチレンテレフタレート、ポリエチレンナフタレートなどのポリエステル系樹脂が好ましい。可動接点を構成する材料としては、導電性材料であれば特に限定されないが、銀、銅、カーボン等からなるものが好ましく用いられる。
The electronic device of the present invention includes a click sheet in which click members are arranged, and a key top provided on the click sheet, and the electromagnetic wave absorbing sheet is laminated on one surface of the click sheet. An electronic device having a key top member for a switch can be given.
As a specific example of such a key top member for a pushbutton switch, the click member has a convex dome shape, and a movable contact made of a conductive film is provided at least on the inner surface of the dome-shaped click member (the lower surface of the click sheet). For example, when the key top is pressed, the click member is deformed so that it can come into contact with, for example, a fixed contact on a printed wiring board disposed thereunder.
The electromagnetic wave absorbing sheet may be laminated on the key top side surface of the click sheet, or may be laminated on the surface opposite to the key top side. When laminated on the surface opposite to the key top side, the electromagnetic wave absorbing sheet is provided so as to be electrically insulated from the movable contact. That is, an electromagnetic wave absorbing sheet may be laminated on the surface of the click sheet excluding a portion having a movable contact, and the electromagnetic wave absorbing sheet is laminated on the entire lower surface of the click sheet. A movable contact may be provided on at least the upper part of the inner surface via an insulating coating. When the electromagnetic wave absorbing sheet is electrically insulated from the movable contact, interference with other keys can be suppressed during key scanning. When the electromagnetic wave absorbing sheet is provided over the entire surface of one surface of the dome-shaped click member, leakage of electromagnetic waves in the millimeter wave band can be prevented.
The click sheet is preferably a polyester resin such as polyethylene terephthalate or polyethylene naphthalate from the viewpoints of deformability by pressing, resilience by repulsion when releasing the pressing force, moldability, and the like. The material constituting the movable contact is not particularly limited as long as it is a conductive material, but a material made of silver, copper, carbon or the like is preferably used.
又、本発明の電子機器としては、少なくとも一方の面に前記に記載の電磁波吸収シートが積層されたプレフォーム用インサートシートを用いてなるものを挙げることができる。
プレフォーム用インサートシートはAV機器のフロントパネル、自動車の計器パネル、押釦などに用いられる成形品の表面に形成されるものであり、透光性基材と、透光性印刷層を有するものである。即ち、透光性基材の一方の面に透光性印刷層を有していてもよく、透光性印刷層を間に挟んで２枚の透光性基材層が積層されていてもよい。本発明のプレフォーム用インサートシートは押釦スイッチに用いられる成形品の表面に形成されるものとして特に有効である。
透光性基材の一方の面に透光性印刷層を有するインサートシートの場合は、電磁波吸収シートは透光性印刷層と異なる面に積層されているのが好ましく、透光性印刷層を間に挟んで２枚の透光性基材層が積層されている場合はどちらの面に積層されていてもよい。
電磁波吸収シートの透光性基材と反対側の面に導電層を設けるのが好ましい。導電層としては、金属箔、金属蒸着膜、印刷された導電ペースト等を例示できる。この導電層を設けることにより、電磁波を反射させ、外に逃さない、反射波を再吸収することができる、共振のＱを小さくすることでアンテナ効果を抑制することができる、金属光沢層の機能をも有することができるなどの効果を有する。
Moreover, as an electronic device of this invention, what uses the insert sheet for preforms which the above-mentioned electromagnetic wave absorption sheet was laminated | stacked on the at least one surface can be mentioned.
The insert sheet for preform is formed on the surface of a molded product used for a front panel of AV equipment, an instrument panel of an automobile, a push button, etc., and has a translucent substrate and a translucent printing layer. is there. That is, a light-transmitting printed layer may be provided on one surface of the light-transmitting substrate, or two light-transmitting substrate layers may be laminated with the light-transmitting printed layer interposed therebetween. Good. The insert sheet for preform of the present invention is particularly effective as being formed on the surface of a molded product used for a push button switch.
In the case of an insert sheet having a translucent printing layer on one side of the translucent substrate, the electromagnetic wave absorbing sheet is preferably laminated on a different surface from the translucent printing layer. When two light-transmitting base material layers are laminated with a gap therebetween, they may be laminated on either side.
It is preferable to provide a conductive layer on the surface of the electromagnetic wave absorbing sheet opposite to the translucent substrate. Examples of the conductive layer include metal foil, metal vapor deposition film, printed conductive paste, and the like. By providing this conductive layer, the function of the metallic luster layer that can reflect the electromagnetic wave, does not escape to the outside, can reabsorb the reflected wave, and can suppress the antenna effect by reducing the resonance Q. It has the effect that it can also have.
以下に、実施例を用いて、本発明をさらに詳しく説明する。
（評価）
表面観察：キーエンス製レーザー顕微鏡ＶＫ−９５００により、倍率４０００倍で、表面を観察した。
表面抵抗：ダイアインスツルメンツ製ＭＣＰ−Ｔ６００により、測定電圧１０Ｖで直流４端子法で測定した。測定点数５点の平均値で示した。
電磁波吸収機能層の厚み測定：日本電子製走査電子顕微鏡（ＳＥＭ）ＪＥＭ−２１００Ｆを用い、電磁波吸収シートの断面電子顕微鏡写真（倍率５００００倍）から測定した。
電磁波吸収特性：キーコム製近傍界用電波吸収材料測定装置を用い、Ｓパラメータ法によるＳ２１（透過量）とＳ１１（反射量）を測定した。ネットワークアナライザーは、アンリツ製ベクトルネットワークアナライザー３７２４７Ｃを用い、テストフィクスチャーにはキーコム製のＴＦ−３Ａ、ＴＦ−１８Ａを用いた。
Hereinafter, the present invention will be described in more detail with reference to examples.
(Evaluation)
Surface observation: The surface was observed with a Keyence laser microscope VK-9500 at a magnification of 4000 times.
Surface resistance: Measured by a DC four-terminal method with a measurement voltage of 10 V using Dia Instruments MCP-T600. The average value of 5 measurement points was shown.
Measurement of thickness of electromagnetic wave absorbing functional layer: Measured from a cross-sectional electron micrograph (magnification of 50000 times) of an electromagnetic wave absorbing sheet using JEM scanning electron microscope (SEM) JEM-2100F.
Electromagnetic wave absorption characteristics: S21 (transmission amount) and S11 (reflection amount) by the S-parameter method were measured using a near field electromagnetic wave absorption material measuring device manufactured by Keycom. As a network analyzer, an Anritsu vector network analyzer 37247C was used, and TF-3A and TF-18A made by Keycom were used as test fixtures.
（実施例１）
支持体として１２μｍ厚のポリエチレンテレフタレートフィルム（常温での剪断弾性率３．８×１０９Ｐａ）上に、有機高分子として２０μｍ厚のシリコーンゴム｛常温での剪断弾性率：１×１０７Ｐａ、常温での炭酸ガス透過率：２．２×１０−７ｃｍ３（ＳＴＰ）ｃｍ（ｃｍ×ｓｅｃ×ｃｍＨｇ）−１、湿式シリカ含有｝を設け、この上に、膜厚換算で３０ｎｍのＦｅ−Ｎｉ系軟磁性金属を、対向ターゲット型マグネトロンスパッタ法により、基板温度を常温に保ち、８ｅＶの粒子エネルギーを持つようわずかに負の電圧を印加し、スパッタを行った。電磁波吸収シートの表面抵抗を注意深く直流４端子法で測定し、所望の大きさに整え、総厚３２μｍの電磁波吸収シートを得た。スパッタ前後の表面観察を行い、次いで得られた試料の一部をミクロトームで薄片にし、断面にイオンビームポリシャーを施し、電磁波吸収機能層の厚みを計測し、電磁波吸収特性の測定を行った。
結果のまとめを表１に、表面観察結果を図２（ａ）、（ｂ）、図３（ａ）、（ｂ）に、電磁波吸収機能層の断面観察を図４に、０．０５〜３ＧＨｚの電磁波吸収特性を図５に示す。図５において、太線は入射電磁波量を基準（０）とした時の電磁波透過量を示し、細線は電磁波反射量を示す。
(Example 1)
On a polyethylene terephthalate film having a thickness of 12 μm as a support (shear elastic modulus at room temperature 3.8 × 10 9 Pa), a silicone rubber having a thickness of 20 μm as an organic polymer {shear elastic modulus at normal temperature: 1 × 10 7 Pa, Carbon dioxide gas permeability at normal temperature: 2.2 × 10 −7 cm 3 (STP) cm (cm × sec × cmHg) −1 , wet silica contained} is provided, and on this, Fe— The Ni-based soft magnetic metal was sputtered by facing the magnetron sputtering method while keeping the substrate temperature at room temperature and applying a slight negative voltage so as to have a particle energy of 8 eV. The surface resistance of the electromagnetic wave absorbing sheet was carefully measured by a direct current four-terminal method, adjusted to a desired size, and an electromagnetic wave absorbing sheet having a total thickness of 32 μm was obtained. Surface observation before and after sputtering was performed, and then a part of the obtained sample was sliced with a microtome, an ion beam polisher was applied to the cross section, the thickness of the electromagnetic wave absorption functional layer was measured, and the electromagnetic wave absorption characteristics were measured.
The summary of the results is shown in Table 1, the surface observation results are shown in FIGS. 2 (a), 2 (b), 3 (a) and 3 (b), the cross-sectional observation of the electromagnetic wave absorption functional layer is shown in FIG. The electromagnetic wave absorption characteristics are shown in FIG. In FIG. 5, the thick line indicates the electromagnetic wave transmission amount when the incident electromagnetic wave amount is set as a reference (0), and the thin line indicates the electromagnetic wave reflection amount.
（実施例２）
実施例１と同様の支持体に、有機高分子として６０μｍ厚のシリコーンゲル｛常温での剪断弾性率：５×１０４Ｐａ、常温での炭酸ガス透過率：２×１０−７［ｃｍ３（ＳＴＰ）ｃｍ／（ｃｍ２×ｓ×ｃｍＨｇ）］を設け、この上に、膜厚換算で８０ｎｍのＦｅ−Ｎｉ系軟磁性金属を、バイアスマグネトロンスパッタ法により、基板温度を常温に保ち、２０ｅＶの粒子エネルギーを持つようバイアス電圧を調整しスパッタを行い、総厚７２μｍの電磁波吸収シートを得た。以下実施例１と同様に表面抵抗、電磁波吸収機能層の厚みと電磁波吸収特性を測定した。
結果のまとめを表１に、０．０５〜１８ＧＨｚの電磁波吸収特性を図６に示す。図６において、太線は入射電磁波量を基準（０）とした時の電磁波透過量を示し、細線は電磁波反射量を示す。
(Example 2)
A silicone gel having a thickness of 60 μm as an organic polymer {shear elastic modulus at room temperature: 5 × 10 4 Pa, carbon dioxide gas permeability at room temperature: 2 × 10 −7 [cm 3 ( STP) cm / (cm 2 × s × cmHg)], and an Fe—Ni soft magnetic metal of 80 nm in terms of film thickness is maintained on the substrate at room temperature by bias magnetron sputtering, and 20 eV Sputtering was performed by adjusting the bias voltage so as to have particle energy, and an electromagnetic wave absorbing sheet having a total thickness of 72 μm was obtained. In the same manner as in Example 1, the surface resistance, the thickness of the electromagnetic wave absorption functional layer, and the electromagnetic wave absorption characteristics were measured.
A summary of the results is shown in Table 1, and electromagnetic wave absorption characteristics of 0.05 to 18 GHz are shown in FIG. In FIG. 6, the thick line indicates the electromagnetic wave transmission amount when the incident electromagnetic wave amount is set as a reference (0), and the thin line indicates the electromagnetic wave reflection amount.
（実施例３）
有機高分子基体として１００μｍ厚のポリアクリロニトリルシート｛常温での剪断弾性率：１．７×１０９Ｐａ、１６０℃における剪断弾性率：１．５×１０６Ｐａ、常温での炭酸ガス透過率：５．３×１０−８［ｃｍ３（ＳＴＰ）ｃｍ／（ｃｍ２×ｓ×ｃｍＨｇ）］、常温での酸素ガス透過率２．８×１０−１５［ｃｍ３（ＳＴＰ）ｃｍ／（ｃｍ２×ｓ×ｃｍＨｇ）］を設け、この上に、膜厚換算で６０ｎｍのＮｉ金属を、対向ターゲット型マグネトロンスパッタ法により、基板温度を１６０℃に保ち、１００ｅＶの粒子エネルギーを持つようバイアス電圧を調整しスパッタを行い、総厚１００μｍの電磁波吸収シートを得た。以下実施例２と同様に表面抵抗、電磁波吸収機能層の厚みと電磁波吸収特性を測定した。
結果のまとめを表１に、０．０５〜１８ＧＨｚの電磁波吸収特性を図７に示す。図７において、太線は入射電磁波量を基準（０）とした時の電磁波透過量を示し、細線は電磁波反射量を示す。
(Example 3)
100 μm-thick polyacrylonitrile sheet as an organic polymer substrate {shear elastic modulus at normal temperature: 1.7 × 10 9 Pa, shear elastic modulus at 160 ° C .: 1.5 × 10 6 Pa, carbon dioxide gas permeability at normal temperature: 5.3 × 10 −8 [cm 3 (STP) cm / (cm 2 × s × cm Hg)], oxygen gas permeability at room temperature 2.8 × 10 −15 [cm 3 (STP) cm / (cm 2 × s × cmHg)], and a bias voltage is adjusted so that the substrate temperature is kept at 160 ° C. and the particle energy is 100 eV by using a counter-target magnetron sputtering method with Ni metal having a thickness of 60 nm. Sputtering was performed to obtain an electromagnetic wave absorbing sheet having a total thickness of 100 μm. In the same manner as in Example 2, the surface resistance, the thickness of the electromagnetic wave absorption functional layer, and the electromagnetic wave absorption characteristics were measured.
A summary of the results is shown in Table 1, and electromagnetic wave absorption characteristics of 0.05 to 18 GHz are shown in FIG. In FIG. 7, the thick line indicates the electromagnetic wave transmission amount when the incident electromagnetic wave amount is set as a reference (0), and the thin line indicates the electromagnetic wave reflection amount.
（比較例１）
表面を酸化させ不導体膜を有した扁平状のＦｅ−Ｎｉ系軟磁性金属粉（平均粒径：１５μｍ、アスペクト比：６５）９４重量部に、ポリウレタン樹脂５重量部、硬化剤としてイソシアネート化合物１重量部、溶剤（シクロヘキサノンとトルエンの１：１混合物）３０重量部を加えたペーストを乾燥後の厚みが１．１ｍｍとなるよう、バーコート法で塗布して膜を形成し、十分乾燥させた後、真空加熱プレスし、８５℃で２４時間キュアリングして膜厚１ｍｍの電磁波吸収体を得た。次いで、実施例２と同様に表面抵抗、電磁波吸収機能層の厚みと電磁波吸収特性を測定した。
結果のまとめを表１に、０．０５〜３ＧＨｚの電磁波吸収特性を図８に示す。
図８において、太線は入射電磁波量を基準（０）とした時の電磁波透過量を示し、細線は電磁波反射量を示す。
(Comparative Example 1)
94 parts by weight of flat Fe-Ni soft magnetic metal powder (average particle size: 15 μm, aspect ratio: 65) having a non-conductive film oxidized on the surface, 5 parts by weight of polyurethane resin, and
A summary of the results is shown in Table 1, and electromagnetic wave absorption characteristics of 0.05 to 3 GHz are shown in FIG.
In FIG. 8, the thick line indicates the electromagnetic wave transmission amount when the incident electromagnetic wave amount is set as a reference (0), and the thin line indicates the electromagnetic wave reflection amount.
（比較例２）
平均粒径８μｍ、アスペクト比３１の粒子を用い、ペーストを乾燥後に、厚みが０．０３ｍｍになるようにしたこと以外、比較例１と同様に処理した。実施例２と同様に表面抵抗、電磁波吸収機能層の厚みと電磁波吸収特性を測定した。
結果のまとめを表１に、０．０５〜１８ＧＨｚの電磁波吸収特性を図９に示す。図９において、太線は入射電磁波量を基準（０）とした時の電磁波透過量を示し、細線は電磁波反射量を示す。
(Comparative Example 2)
The treatment was performed in the same manner as in Comparative Example 1 except that particles having an average particle diameter of 8 μm and an aspect ratio of 31 were used, and the thickness of the paste was 0.03 mm after drying. In the same manner as in Example 2, the surface resistance, the thickness of the electromagnetic wave absorption functional layer, and the electromagnetic wave absorption characteristics were measured.
A summary of the results is shown in Table 1, and electromagnetic wave absorption characteristics of 0.05 to 18 GHz are shown in FIG. In FIG. 9, the thick line indicates the electromagnetic wave transmission amount when the incident electromagnetic wave amount is the reference (0), and the thin line indicates the electromagnetic wave reflection amount.
（比較例３）
ＥＢ蒸着装置で蒸着を行ったこと以外は実施例２と同様にした。粒子エネルギーは１ｅＶであった。
結果のまとめを表１に、０．０５〜３ＧＨｚの電磁波吸収特性を図１０に示す。図１０において、太線は入射電磁波量を基準（０）とした時の電磁波透過量を示し、細線は電磁波反射量を示す。
(Comparative Example 3)
The same procedure as in Example 2 was performed except that vapor deposition was performed using an EB vapor deposition apparatus. The particle energy was 1 eV.
A summary of the results is shown in Table 1, and electromagnetic wave absorption characteristics of 0.05 to 3 GHz are shown in FIG. In FIG. 10, the thick line indicates the electromagnetic wave transmission amount when the incident electromagnetic wave amount is set as a reference (0), and the thin line indicates the electromagnetic wave reflection amount.
表１において、
ＰＥＴ：ポリエチレンテレフタレートフィルム
ＳＲ：シリコーンゴム
ＰＡＮ：ポリアクリロニトリル
ＰＵ：ポリウレタン樹脂
を示す。
In Table 1,
PET: Polyethylene terephthalate film SR: Silicone rubber PAN: Polyacrylonitrile PU: Polyurethane resin.
表１および図５〜９から、実施例１〜３、比較例１、２の電磁波吸収特性、すなわち透過減衰量と反射減衰量の傾向はほぼ同様で、低周波領域では、反射減衰量が大きく、透過減衰量が小さい。周波数が上がるにしたがって、透過減衰量は増加してくる。
実施例１〜３で、強磁性体量と最大透過減衰量とは相関が見られ、強磁性体量が多いほど、大きな減衰量を示している。
電磁波吸収機能層は薄く、比較例３と同程度の透過減衰特性と反射減衰特性を有している。比較例１では、電磁波吸収機能層（総厚と同じ）が、１０００μｍと厚く、実施例と同程度の透過減衰量、反射減衰量を示しているが、有機高分子の割合が少ないため、衝撃がかかった場合に壊れやすい。透過減衰量も低周波領域では、あまり大きな値ではなく、実施例と比較すると帯域は狭い。
比較例２では、厚みは薄いが、それと共に吸収特性も悪くなるため、電磁波吸収機能層厚みあたりの最大透過減衰量は、比較例１と同様に小さく、１０ｄＢもなく、実効的に吸収能力があるとはいい難い。比較例３は、蒸着時の超微粒子のエネルギーが小さいため、有機高分子の表面に均一な金属となっており、図１０のとおり金属と似た挙動を示し、金属特有のピークがあり、反射によって透過減衰をもたらしている。その吸収効果は小さいもので電磁波シールドとして機能している。
実施例１〜３の電磁波吸収シートは電磁波最大透過減衰量／電磁波吸収機能層が大きく、厚みに対しての吸収特性は優れており、かつ、有機高分子の特性を残していて、薄く、軽く、伸度および可撓性を有する。
From Table 1 and FIGS. 5 to 9, the electromagnetic wave absorption characteristics of Examples 1 to 3 and Comparative Examples 1 and 2, that is, the tendency of transmission attenuation and reflection attenuation is almost the same, and the reflection attenuation is large in the low frequency region. The transmission attenuation is small. As the frequency increases, the transmission attenuation increases.
In Examples 1 to 3, there is a correlation between the amount of ferromagnetic material and the maximum transmission attenuation, and the larger the amount of ferromagnetic material, the larger the amount of attenuation.
The electromagnetic wave absorption functional layer is thin and has transmission attenuation characteristics and reflection attenuation characteristics comparable to those of Comparative Example 3. In Comparative Example 1, the electromagnetic wave absorption functional layer (same as the total thickness) is as thick as 1000 μm, and shows the same amount of transmission attenuation and reflection attenuation as in the examples. It is fragile when applied. The transmission attenuation amount is not so large in the low frequency region, and the band is narrower than in the embodiment.
In Comparative Example 2, the thickness is thin, but the absorption characteristics are also deteriorated. Therefore, the maximum transmission attenuation per electromagnetic wave absorbing functional layer thickness is as small as Comparative Example 1, and there is no 10 dB, and the effective absorption capacity is obtained. It is hard to be there. In Comparative Example 3, since the energy of the ultrafine particles during vapor deposition is small, the surface of the organic polymer is a uniform metal, shows behavior similar to that of the metal as shown in FIG. Causes transmission attenuation. The absorption effect is small and functions as an electromagnetic wave shield.
The electromagnetic wave absorption sheets of Examples 1 to 3 have a large electromagnetic wave maximum transmission attenuation / electromagnetic wave absorption functional layer, excellent absorption characteristics with respect to thickness, and are thin and light while retaining the characteristics of organic polymers. Has elongation and flexibility.
１：有機高分子、 ２：電磁波吸収機能層、 ３：強磁性体
1: organic polymer, 2: electromagnetic wave absorption functional layer, 3: ferromagnetic material
Claims (17)
The electromagnetic wave noise control electronic device which uses the insert sheet for preform in which the electromagnetic wave absorption sheet of any one of Claims 1-5 was laminated | stacked on the at least one surface.
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| JP2003343631A JP4173424B2 (en) | 2003-06-18 | 2003-10-01 | Electromagnetic wave absorbing sheet, electronic device, and method of manufacturing electromagnetic wave absorbing sheet |
| US10/540,825 US7625633B2 (en) | 2003-03-25 | 2004-03-23 | Electromagnetic noise suppressor, article with electromagnetic noise suppressing function, and their manufacturing methods |
| PCT/JP2004/003951 WO2004086837A1 (en) | 2003-03-25 | 2004-03-23 | Electromagnetic noise suppressor, article with electromagnetic noise suppression function, and their manufacturing methods |
| TW93107868A TWI269632B (en) | 2003-03-25 | 2004-03-24 | Noise suppressor, article having noise suppression function, and manufacturing method therefor |
| US12/551,230 US20090314411A1 (en) | 2003-03-25 | 2009-08-31 | Electromagnetic noise suppressor, article with electromagnetic noise suppressing function and their manufacturing methods |
| US12/551,156 US7887911B2 (en) | 2003-03-25 | 2009-08-31 | Electromagnetic noise suppressor, article with electromagnetic noise suppressing function and their manufacturing methods |
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| JP2006295101A (en) * | 2005-03-14 | 2006-10-26 | Shin Etsu Polymer Co Ltd | Noise suppressor, wiring member and multilayer circuit board |
| JP2008041947A (en) * | 2006-08-07 | 2008-02-21 | Shin Etsu Polymer Co Ltd | Method for manufacturing wiring member |
| WO2012074024A1 (en) * | 2010-11-30 | 2012-06-07 | 住友大阪セメント株式会社 | Composite magnet and production method therefor, antenna, and communication device |
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| KR20210145272A (en) * | 2019-05-14 | 2021-12-01 | 후지필름 가부시키가이샤 | radio wave absorber |
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| JP2006295101A (en) * | 2005-03-14 | 2006-10-26 | Shin Etsu Polymer Co Ltd | Noise suppressor, wiring member and multilayer circuit board |
| JP4515342B2 (en) * | 2005-03-14 | 2010-07-28 | 信越ポリマー株式会社 | Multilayer circuit board |
| JP2008041947A (en) * | 2006-08-07 | 2008-02-21 | Shin Etsu Polymer Co Ltd | Method for manufacturing wiring member |
| WO2012074024A1 (en) * | 2010-11-30 | 2012-06-07 | 住友大阪セメント株式会社 | Composite magnet and production method therefor, antenna, and communication device |
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| KR20210145272A (en) * | 2019-05-14 | 2021-12-01 | 후지필름 가부시키가이샤 | radio wave absorber |
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