JP2004158599A

JP2004158599A - Noise filter

Info

Publication number: JP2004158599A
Application number: JP2002322251A
Authority: JP
Inventors: Naotsugu Yoneda; 尚継米田; Shogo Nakayama; 祥吾中山
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2002-11-06
Filing date: 2002-11-06
Publication date: 2004-06-03
Anticipated expiration: 2022-11-06
Also published as: JP4147904B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noise filter enhanced in the common mode impedance level and excellent in common mode noise rejection characteristics. <P>SOLUTION: A first coil 31, a second coil 34, and a third coil 37 are provided in a magnetic body. The first coil 31 comprises a first conductor 32 spiral in shape and a second conductor 33 spiral in shape and formed above the first conductor 32. The third coil 37 comprises a fifth conductor 38 spiral in shape and positioned above the second conductor 33 and facing the same, and a sixth conductor 39 spiral in shape and formed above the fifth conductor 38. The second coil 34 comprises a third conductor 35 shaping a double spiral in collaboration with the first conductor 32 on one and the same plane, and a fourth conductor 36 shaping a double spiral in collaboration with the sixth conductor 39 on one and the same plane. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、携帯電話、情報機器等のノイズ対策として使用されるノイズフィルタに関するものである。
【０００２】
【従来の技術】
従来のこの種のノイズフィルタは、図５に示されるような構成を有していた。
【０００３】
図５は従来のノイズフィルタ（積層コモンモードチョークコイル）の分解斜視図を示したもので、この図５に基づいて、従来のノイズフィルタの構成を説明する。
【０００４】
図５において、１は第１の絶縁性シートで、表面に第１のコイル導体２を設けている。３は第２の絶縁性シートで、表面に第２のコイル導体４を設けている。５は第３の絶縁性シートで、表面に第３のコイル導体６を設けている。７は第４の絶縁性シートで、表面に第４のコイル導体８を設けている。そして前記第１の絶縁性シート１、第２の絶縁性シート３、第３の絶縁性シート５、第４の絶縁性シート７を順次積層することにより、第１のコイル導体２の他端部は、第１の絶縁性シート１に設けたバイアホール１ａを介して第２のコイル導体４の一端部に電気的に直列に接続され、かつ第２のコイル導体４の他端部は、第２の絶縁性シート３に設けたバイアホール３ａを介して第３のコイル導体６の一端部に電気的に直列に接続され、さらに第３のコイル導体６の他端部は、第３の絶縁性シート５に設けたバイアホール５ａを介して第４のコイル導体８の一端部に電気的に直列に接続されるもので、このように、前記第１の絶縁性シート１、第２の絶縁性シート３、第３の絶縁性シート５、第４の絶縁性シート７を順次積層することにより、絶縁性シート１，３，５，７を積み重ねる上下方向に対して平行な軸を有する第１の螺旋状コイル９が構成されるものである。
【０００５】
１０は第５の絶縁性シートで、表面に第５のコイル導体１１を設けている。１２は第６の絶縁性シートで、表面に第６のコイル導体１３を設けている。１４は第７の絶縁性シートで、表面に第７のコイル導体１５を設けている。１６は第８の絶縁性シートで、表面に第８のコイル導体１７を設けている。そして前記第５の絶縁性シート１０、第６の絶縁性シート１２、第７の絶縁性シート１４、第８の絶縁性シート１６を順次積層することにより、第５のコイル導体１１の他端部は、第５の絶縁性シート１０に設けたバイアホール１０ａを介して第６のコイル導体１３の一端部に電気的に直列に接続され、かつ第６のコイル導体１３の他端部は、第６の絶縁性シート１２に設けたバイアホール１２ａを介して第７のコイル導体１５の一端部に電気的に直列に接続され、さらに第７のコイル導体１５の他端部は、第７の絶縁性シート１４に設けたバイアホール１４ａを介して第８のコイル導体１７の一端部に電気的に直列に接続されるもので、このように、前記第５の絶縁性シート１０、第６の絶縁性シート１２、第７の絶縁性シート１４、第８の絶縁性シート１６を順次積層することにより、絶縁性シート１０，１２，１４，１６を積み重ねる上下方向に対して平行な軸を有する第２の螺旋状コイル１８が構成されるものである。
【０００６】
１９は第９の絶縁性シートで、表面に第９のコイル導体２０を設けている。２１は第１０の絶縁性シートで、表面に第１０のコイル導体２２を設けている。２３は第１１の絶縁性シートで、表面に第１１のコイル導体２４を設けている。２５は第１２の絶縁性シートで、表面に第１２のコイル導体２６を設けている。そして前記第９の絶縁性シート１９、第１０の絶縁性シート２１、第１１の絶縁性シート２３、第１２の絶縁性シート２５を順次積層することにより、第９のコイル導体２０の他端部は、第９の絶縁性シート１９に設けたバイアホール１９ａを介して第１０のコイル導体２２の一端部に電気的に直列に接続され、かつ第１０のコイル導体２２の他端部は、第１０の絶縁性シート２１に設けたバイアホール２１ａを介して第１１のコイル導体２４の一端部に電気的に直列に接続され、さらに第１１のコイル導体２４の他端部は、第１１の絶縁性シート２３に設けたバイアホール２３ａを介して第１２のコイル導体２６の一端部に電気的に直列に接続されるもので、このように、前記第９の絶縁性シート１９、第１０の絶縁性シート２１、第１１の絶縁性シート２３、第１２の絶縁性シート２５を順次積層することにより、絶縁性シート１９，２１，２３，２５を積み重ねる上下方向に対して平行な軸を有する第３の螺旋状コイル２７が構成されるものである。
【０００７】
そして前記第１の螺旋状コイル９の上側と第３の螺旋状コイル２７の下側にカバーシート２８，２９を位置させて第１の螺旋状コイル９、第２の螺旋状コイル１８、第３の螺旋状コイル２７を積層することにより、積層体からなる積層コモンモードチョークコイル（ノイズフィルタ）を構成している。
【０００８】
前記積層体からなる積層コモンモードチョークコイル（ノイズフィルタ）には入力電極２８ａ，２８ｂ，２８ｃと、出力電極２９ａ，２９ｂ，２９ｃが設けられているもので、前記入力電極２８ａと出力電極２９ａは第１の螺旋状コイル９に電気的に接続されて第１の螺旋状コイル９の入力電極２８ａと出力電極２９ａを構成し、また前記入力電極２８ｂと出力電極２９ｂは第２の螺旋状コイル１８に電気的に接続されて第２の螺旋状コイル１８の入力電極２８ｂと出力電極２９ｂを構成し、さらに前記入力電極２８ｃと出力電極２９ｃは第３の螺旋状コイル２７に電気的に接続されて第３の螺旋状コイル２７の入力電極２８ｃと出力電極２９ｃを構成している。
【０００９】
なお、この出願の発明に関連する先行技術文献情報としては、例えば、特許文献１が知られている。
【００１０】
【特許文献１】
特開平１１−１８６０５６号公報
【００１１】
【発明が解決しようとする課題】
しかしながら、上記従来のノイズフィルタは、すべてのコイル、すなわち、第１の螺旋状コイル９、第２の螺旋状コイル１８、第３の螺旋状コイル２７の構造がそれぞれ独立の螺旋状となっているため、積層数が多くなり、その結果、第１の螺旋状コイル９と第２の螺旋状コイル１８との結合係数、第２の螺旋状コイル１８と第３の螺旋状コイル２７との結合係数を高めるのにも限界があり、そのため、第１の螺旋状コイル９と第３の螺旋状コイル２７はほとんど結合を有しないという課題を有していた。
【００１２】
本発明は上記従来の課題を解決するもので、コモンモードのインピーダンス値を高くでき、かつコモンモードのノイズの除去特性も高いノイズフィルタを提供することを目的とするものである。
【００１３】
【課題を解決するための手段】
上記目的を達成するために、本発明は以下の構成を有するものである。
【００１４】
本発明の請求項１に記載の発明は、磁性体と、この磁性体内に設けられた第１のコイル、第２のコイルおよび第３のコイルと、前記第１のコイル、第２のコイルおよび第３のコイルの各両端部とそれぞれ電気的に接続された外部電極とを備え、前記第１のコイルは、渦巻き状の第１の導体と、この第１の導体と電気的に接続され、かつ第１の導体の上方に渦巻き状に形成されている第２の導体とにより構成し、前記第３のコイルは、前記第２の導体の上方に対向して渦巻き状に形成されている第５の導体と、この第５の導体と電気的に接続され、かつ第５の導体の上方に渦巻き状に形成されている第６の導体とにより構成し、さらに前記第２のコイルは、前記第１の導体と同一平面上に２重の渦巻き状に形成されている第３の導体と、この第３の導体と電気的に接続され、かつ前記第６の導体と同一平面上に２重の渦巻き状に形成されている第４の導体とにより構成したもので、この構成によれば、第１のコイルと第２のコイルとの結合係数、第２のコイルと第３のコイルとの結合係数、および第３のコイルと第１のコイルとの結合係数がすべて高くなるため、積層数もコイル導体層としては４層のみで結合係数の高い３ラインのノイズフィルタを提供できるという作用効果が得られるものである。
【００１５】
本発明の請求項２に記載の発明は、特に、第１のコイルの外部電極間の導体の長さと、第２のコイルの外部電極間の導体の長さおよび第３のコイルの外部電極間の導体の長さをそれぞれ同じ長さにしたもので、この構成によれば、直流抵抗のバランスがとれた３ラインのノイズフィルタを提供できるという作用効果が得られるものである。
【００１６】
本発明の請求項３に記載の発明は、特に、第１の導体と第３の導体間の距離と、第４の導体と第６の導体間の距離を、それぞれ３０μｍより長く、かつ１５０μｍより短くしたもので、この構成によれば、結合係数の高い３ラインのノイズフィルタを提供できるという作用効果が得られるものである。
【００１７】
本発明の請求項４に記載の発明は、特に、第１の導体と第３の導体間の距離と、第４の導体と第６の導体間の距離を同一にしたもので、この構成によれば、結合係数のバランスがとれた３ラインのノイズフィルタを提供できるという作用効果が得られるものである。
【００１８】
本発明の請求項５に記載の発明は、特に、第２の導体が形成されている面と第５の導体が形成されている面間の距離を、前記第２の導体が形成されている面と第３の導体が形成されている面間の距離と、第４の導体が形成されている面と第５の導体が形成されている面間の距離のいずれよりも短くしたもので、この構成によれば、結合係数のバランスがとれた３ラインのノイズフィルタを提供できるという作用効果が得られるものである。
【００１９】
本発明の請求項６に記載の発明は、特に、第１のコイル、第２のコイルおよび第３のコイルをそれぞれ電鋳法により形成したもので、この構成によれば、直流抵抗の低い３ラインのノイズフィルタを提供できるという作用効果が得られるものである。
【００２０】
【発明の実施の形態】
以下、本発明の一実施の形態におけるノイズフィルタについて、図面を参照しながら説明する。
【００２１】
図１は本発明の一実施の形態におけるノイズフィルタの分解斜視図、図２は同ノイズフィルタの斜視図である。
【００２２】
図１、図２において、３１は第１のコイルで、この第１のコイル３１は、渦巻き状の第１の導体３２と、この第１の導体３２の上方に渦巻き状に形成されている第２の導体３３とにより構成されている。そして前記第１の導体３２は第１の引き出し部３２ａと、渦巻きの内部に位置する第１のバイア電極３２ｂとを有し、また第２の導体３３は第２の引き出し部３３ａと、渦巻きの内部に位置する第２のバイア電極３３ｂとを有している。
【００２３】
３４は第２のコイルで、この第２のコイル３４は、渦巻き状の第３の導体３５と、この第３の導体３５の上方に渦巻き状に形成されている第４の導体３６とにより構成されている。そして前記第３の導体３５は第３の引き出し部３５ａと、渦巻きの内部に位置する第３のバイア電極３５ｂとを有し、また第４の導体３６は第４の引き出し部３６ａと、渦巻きの内部に位置する第４のバイア電極３６ｂとを有している。
【００２４】
３７は第３のコイルで、この第３のコイル３７は、渦巻き状の第５の導体３８と、この第５の導体３８の上方に渦巻き状に形成されている第６の導体３９とにより構成されている。そして前記第５の導体３８は第５の引き出し部３８ａと、渦巻きの内部に位置する第５のバイア電極３８ｂとを有し、また第６の導体３９は第６の引き出し部３９ａと、渦巻きの内部に位置する第６のバイア電極３９ｂとを有している。
【００２５】
４０は方形状をなす第１の磁性体シートで、この第１の磁性体シート４０は前記第１の導体３２と第２の導体３３との間に配設され、かつ第１のバイアホール４０ａと第２のバイアホール４０ｂを有している。そしてこの第１のバイアホール４０ａによって前記第１のバイア電極３２ｂと第２のバイア電極３３ｂとが互いに電気的に接続され、これにより、第１の導体３２と第２の導体３３とが電気的に接続されて第１のコイル３１を形成している。
【００２６】
４１は方形状をなす第２の磁性体シートで、この第２の磁性体シート４１は前記第２の導体３３と第５の導体３８との間に配設され、かつ第３のバイアホール４１ａを有している。そしてこの第２の磁性体シート４１によって第２の導体３３と第５の導体３８との間を絶縁している。
【００２７】
４２は方形状をなす第３の磁性体シートで、この第３の磁性体シート４２は前記第５の導体３８と第６の導体３９との間に配設され、かつ第４のバイアホール４２ａと第５のバイアホール４２ｂを有している。そしてこの第４のバイアホール４２ａと、前記第２のバイアホール４０ｂおよび第３のバイアホール４１ａとによって前記第３のバイア電極３５ｂと第４のバイア電極３６ｂとが互いに電気的に接続され、これにより、第３の導体３５と第４の導体３６とが電気的に接続されて第２のコイル３４を形成している。また、前記第５のバイアホール４２ｂによって前記第５のバイア電極３８ｂと第６のバイア電極３９ｂとが互いに電気的に接続され、これにより、第５の導体３８と第６の導体３９とが電気的に接続されて第３のコイル３７を形成している。
【００２８】
なお、前記第１の導体３２、第２の導体３３、第３の導体３５、第４の導体３６、第５の導体３８、第６の導体３９はそれぞれ銀などの導電体により構成されているもので、それらの長さ、幅、厚みは所定の特性に合致するように調整すればよい。
【００２９】
また、前記第２の導体３３と第５の導体３８は、互いに対向し、かつその間は第２の磁性体シート４１によって絶縁されている。そしてまた、前記第１の導体３２と第３の導体３５、第２の導体３３と第５の導体３８、第４の導体３６と第６の導体３９は、同じ方向に引き出されている第１の引き出し部３２ａ、第３の引き出し部３５ａ、第５の引き出し部３８ａから第２の引き出し部３３ａ、第４の引き出し部３６ａ、第６の引き出し部３９ａへ電流を流したとき、第４の導体３６または第６の導体３９の上方から平面視によりそれぞれ同じ方向に電流が流れるように形成されている。
【００３０】
上記した配置関係となるように、前記第１の導体３２、第２の導体３３、第３の導体３５、第４の導体３６、第５の導体３８、第６の導体３９を形成したことにより、第１の導体３２と第３の導体３５は同一平面上に２重渦巻き状に形成されるため、第１の導体３２と第３の導体３５とに同方向の電流が流れれば、第１の導体３２と第３の導体３５でそれぞれ発生する磁束を互いに強め合うことができ、その結果、コモンモードのインピーダンス値を高くすることができるという効果が得られるものである。
【００３１】
また、第２の導体３３と第５の導体３８は第２の磁性体シート４１を挟んで対向するようにそれぞれ渦巻き状に形成されているため、第２の導体３３と第５の導体３８とに同方向の電流が流れれば、第２の導体３３と第５の導体３８でそれぞれ発生する磁束を互いに強め合うことができるため、コモンモードのインピーダンス値を高くすることができるという効果が得られるものである。
【００３２】
４３は方形状をなす第４の磁性体シートで、この第４の磁性体シート４３は第１の導体３２、第３の導体３５の下面に配設されている。
【００３３】
４４は方形状をなす第５の磁性体シートで、この第５の磁性体シート４４は第４の導体３６、第６の導体３９の上面に配設されている。
【００３４】
そして、前記第１の磁性体シート４０、第２の磁性体シート４１、第３の磁性体シート４２、第４の磁性体シート４３、第５の磁性体シート４４は、フェライト粉体の酸化物および樹脂からなる混合物により構成され、これらを、上記したように上下方向に積層することによって、図２に示すように、方形状をなす板状の磁性体４５を形成している。なお、この磁性体４５は板状でなく、ある程度の厚みを有していてもよい。また、この磁性体４５は必ずしも方形状である必要はない。そしてまた、磁性体４５を構成する前記第１の磁性体シート４０、第２の磁性体シート４１、第３の磁性体シート４２、第４の磁性体シート４３、第５の磁性体シート４４のそれぞれの厚みは、所定の特性（耐電圧など）によって適宜調整すればよく、さらに厚みの調整は、磁性体シート自体の厚みを変えるか、あるいは複数の磁性体シートの枚数を変えることによって行う。
【００３５】
４６ａ，４６ｂ，４６ｃは磁性体４５の一方の端面に形成された外部電極、４７ａ，４７ｂ，４７ｃは前記外部電極４６ａ，４６ｂ，４６ｃと相対向するように磁性体４５の他方の端面に形成された外部電極である。これらの外部電極４６ａ，４６ｂ，４６ｃ，４７ａ，４７ｂ，４７ｃは、銀などの導体の表面に、ニッケルめっき、スズやはんだなどの低融点金属めっきを施すことにより構成されている。
【００３６】
そして、前記第１のコイル３１の両端部、すなわち第１の引き出し部３２ａ、第２の引き出し部３３ａは、第１の引き出し部３２ａが外部電極４６ａと、第２の引き出し部３３ａが外部電極４７ａとそれぞれ電気的に接続されている。また、第２のコイル３４の両端部、すなわち第３の引き出し部３５ａ、第４の引き出し部３６ａは、第３の引き出し部３５ａが外部電極４６ｂと、第４の引き出し部３６ａが外部電極４７ｂとそれぞれ電気的に接続されている。そしてまた、第３のコイル３７の両端部、すなわち第５の引き出し部３８ａ、第６の引き出し部３９ａは、第５の引き出し部３８ａが外部電極４６ｃと、第６の引き出し部３９ａが外部電極４７ｃとそれぞれ電気的に接続されている。
【００３７】
なお、前記第１のコイル３１、第２のコイル３４、第３のコイル３７の長さが同一になるようにすれば、各コイル３１，３４，３７の直流抵抗値は等しくなるため、回路内に組み込んだときにバランスを崩すことがなくなるものである。
【００３８】
また、前記第１のコイル３１と第２のコイル３４との結合係数および第２のコイル３４と第３のコイル３７との結合係数は、第１の導体３２と第３の導体３５間の距離および第４の導体３６と第６の導体３９間の距離で決まるものである。
【００３９】
図３は本発明の一実施の形態におけるノイズフィルタの第１の導体３２と第３の導体３５間の距離と、結合係数Ｋ、耐電圧の関係を示す図である。
【００４０】
なお、耐電圧は第１の導体３２と第３の導体３５との間に１００Ｖを１分間印加したときの良品（絶縁抵抗が１００ＭΩ以上のもの）率を表したもので、図３は横軸に第１の導体３２と第３の導体３５間の距離（μｍ）を、縦軸に結合係数Ｋと耐電圧不良率（％）を示している。
【００４１】
図３から明らかなように、第１の導体３２と第３の導体３５間の距離は３０μｍより長く、かつ１５０μｍより短くすればよいことがわかる。すなわち、このような範囲にすれば、第１の導体３２と第３の導体３５間の耐電圧を保持できて、耐電圧不良率を０％にすることができるとともに、第１の導体３２と第３の導体３５との間の結合係数もアップするため、コモンモードのインピーダンス値を高くできるという効果が得られるものである。また、このことは、第４の導体３６と第６の導体３９との関係においても同様のことが言えるもので、前記第１の導体３２と第３の導体３５間の距離と、第４の導体３６と第６の導体３９間の距離を同一にすれば、第１のコイル３１と第２のコイル３４との結合係数と、第２のコイル３４と第３のコイル３７との結合係数は等しくなるもので、これにより、コモンモードインピーダンスのバランスがとれたコモンモードノイズフィルタを提供することができるものである。
【００４２】
図４（ａ）は従来のノイズフィルタの各コイル間のコモンモードインピーダンスを示したものであり、また図４（ｂ）は本発明の一実施の形態におけるノイズフィルタの各コイル間のコモンモードインピーダンスを示したものである。この図４（ａ）（ｂ）から明らかなように、従来のノイズフィルタでは、第１のコイル９と第３のコイル２７間のコモンモードインピーダンスだけが低く、バランスがとれていないのに対し、本発明の一実施の形態におけるノイズフィルタでは、すべてのコモンモードインピーダンスのバランスがとれているもので、これにより、優れたコモンモードノイズフィルタであることがわかる。
【００４３】
なお、前記第１の導体３２、第２の導体３３、第３の導体３５、第４の導体３６、第５の導体３８、第６の導体３９をそれぞれ電鋳法により形成すれば、狭い導体幅、細かい導体線間ピッチが実現できるため、それぞれの導体３２，３３，３５，３６，３８，３９の長さを長くすることができ、これにより、それぞれの導体３２，３３，３５，３６，３８，３９で発生する磁束を互いにさらに強め合うことができるため、コモンモードインピーダンス値をさらに高くすることができるものである。
【００４４】
【発明の効果】
以上のように本発明のノイズフィルタは、磁性体と、この磁性体内に設けられた第１のコイル、第２のコイルおよび第３のコイルと、前記第１のコイル、第２のコイルおよび第３のコイルの各両端部とそれぞれ電気的に接続された外部電極とを備え、前記第１のコイルは、渦巻き状の第１の導体と、この第１の導体と電気的に接続され、かつ第１の導体の上方に渦巻き状に形成されている第２の導体とにより構成し、前記第３のコイルは、前記第２の導体の上方に対向して渦巻き状に形成されている第５の導体と、この第５の導体と電気的に接続され、かつ第５の導体の上方に渦巻き状に形成されている第６の導体とにより構成し、さらに前記第２のコイルは、前記第１の導体と同一平面上に２重の渦巻き状に形成されている第３の導体と、この第３の導体と電気的に接続され、かつ前記第６の導体と同一平面上に２重の渦巻き状に形成されている第４の導体とにより構成しているため、第１のコイルと第２のコイルとの結合係数、第２のコイルと第３のコイルとの結合係数、および第３のコイルと第１のコイルとの結合係数はすべて高くなり、これにより、積層数もコイル導体層としては４層のみで結合係数の高い３ラインのノイズフィルタを提供できるという優れた効果を奏するものである。
【図面の簡単な説明】
【図１】本発明の一実施の形態におけるノイズフィルタの分解斜視図
【図２】同ノイズフィルタの斜視図
【図３】同ノイズフィルタの第１の導体３２と第３の導体３５間の距離と、結合係数Ｋ、耐電圧の関係を示す図
【図４】（ａ）従来のノイズフィルタの各コイル間のコモンモードインピーダンスを示す図
（ｂ）本発明の一実施の形態におけるノイズフィルタの各コイル間のコモンモードインピーダンスを示す図
【図５】従来のノイズフィルタの分解斜視図
【符号の説明】
３１第１のコイル
３２第１の導体
３３第２の導体
３４第２のコイル
３５第３の導体
３６第４の導体
３７第３のコイル
３８第５の導体
３９第６の導体
４０第１の磁性体シート
４１第２の磁性体シート
４２第３の磁性体シート
４３第４の磁性体シート
４４第５の磁性体シート
４５磁性体
４６ａ〜４６ｃ，４７ａ〜４７ｃ外部電極[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a noise filter used as a noise countermeasure for mobile phones, information devices, and the like.
[0002]
[Prior art]
A conventional noise filter of this type has a configuration as shown in FIG.
[0003]
FIG. 5 is an exploded perspective view of a conventional noise filter (laminated common mode choke coil). The configuration of the conventional noise filter will be described with reference to FIG.
[0004]
In FIG. 5, reference numeral 1 denotes a first insulating sheet, on which a first coil conductor 2 is provided. Reference numeral 3 denotes a second insulating sheet on which a second coil conductor 4 is provided. Reference numeral 5 denotes a third insulating sheet, on the surface of which a third coil conductor 6 is provided. Reference numeral 7 denotes a fourth insulating sheet, on the surface of which a fourth coil conductor 8 is provided. Then, the first insulating sheet 1, the second insulating sheet 3, the third insulating sheet 5, and the fourth insulating sheet 7 are sequentially laminated to form the other end of the first coil conductor 2. Is electrically connected in series to one end of the second coil conductor 4 via a via hole 1a provided in the first insulating sheet 1, and the other end of the second coil conductor 4 is 2 is electrically connected in series to one end of the third coil conductor 6 via a via hole 3 a provided in the insulating sheet 3, and the other end of the third coil conductor 6 is Is electrically connected in series to one end of the fourth coil conductor 8 through a via hole 5a provided in the conductive sheet 5, and thus, the first insulating sheet 1, the second insulating By sequentially laminating the conductive sheet 3, the third insulating sheet 5, and the fourth insulating sheet 7, , In which the first helical coil 9 having an axis parallel with respect to the vertical direction of stacking the insulating sheets 1,3,5,7 are configured.
[0005]
Reference numeral 10 denotes a fifth insulating sheet, on the surface of which a fifth coil conductor 11 is provided. Reference numeral 12 denotes a sixth insulating sheet, on the surface of which a sixth coil conductor 13 is provided. Reference numeral 14 denotes a seventh insulating sheet, on the surface of which a seventh coil conductor 15 is provided. Reference numeral 16 denotes an eighth insulating sheet, on the surface of which an eighth coil conductor 17 is provided. The other end of the fifth coil conductor 11 is formed by sequentially laminating the fifth insulating sheet 10, the sixth insulating sheet 12, the seventh insulating sheet 14, and the eighth insulating sheet 16. Is electrically connected in series to one end of the sixth coil conductor 13 via a via hole 10 a provided in the fifth insulating sheet 10, and the other end of the sixth coil conductor 13 is 6 is electrically connected in series to one end of a seventh coil conductor 15 through a via hole 12a provided in the insulating sheet 12 of the sixth embodiment. Is electrically connected in series to one end of the eighth coil conductor 17 through a via hole 14a provided in the conductive sheet 14, and thus, the fifth insulating sheet 10, the sixth insulating Sheet 12, seventh insulating sheet 14, eighth sheet By sequentially laminating an insulating sheet 16, in which the second helical coil 18 having an axis parallel with respect to the vertical direction of stacking the insulating sheets 10, 12, 14, 16 are configured.
[0006]
Reference numeral 19 denotes a ninth insulating sheet, on the surface of which a ninth coil conductor 20 is provided. Reference numeral 21 denotes a tenth insulating sheet, on the surface of which a tenth coil conductor 22 is provided. An eleventh insulating sheet 23 has an eleventh coil conductor 24 on its surface. Reference numeral 25 denotes a twelfth insulating sheet, on the surface of which a twelfth coil conductor 26 is provided. The ninth insulating sheet 19, the tenth insulating sheet 21, the eleventh insulating sheet 23, and the twelfth insulating sheet 25 are sequentially laminated to form the other end of the ninth coil conductor 20. Is electrically connected in series to one end of the tenth coil conductor 22 via a via hole 19a provided in the ninth insulating sheet 19, and the other end of the tenth coil conductor 22 is The other end of the eleventh coil conductor 24 is electrically connected in series to one end of the eleventh coil conductor 24 via a via hole 21 a provided in the ten insulating sheets 21. Is electrically connected in series to one end of the twelfth coil conductor 26 through a via hole 23a provided in the conductive sheet 23. Thus, the ninth insulating sheet 19, the tenth insulating Sheet 21, eleventh By sequentially laminating the insulating sheet 23 and the twelfth insulating sheet 25, a third spiral coil 27 having an axis parallel to the vertical direction in which the insulating sheets 19, 21, 23, and 25 are stacked is configured. Is what is done.
[0007]
Then, the cover sheets 28 and 29 are positioned above the first spiral coil 9 and below the third spiral coil 27, and the first spiral coil 9, the second spiral coil 18, the third spiral coil Are laminated to form a laminated common mode choke coil (noise filter) composed of a laminated body.
[0008]
The laminated common mode choke coil (noise filter) made of the laminated body is provided with input electrodes 28a, 28b, 28c and output electrodes 29a, 29b, 29c, and the input electrode 28a and the output electrode 29a are The first spiral coil 9 is electrically connected to form an input electrode 28a and an output electrode 29a of the first spiral coil 9, and the input electrode 28b and the output electrode 29b are connected to the second spiral coil 18. The input electrode 28b and the output electrode 29b of the second spiral coil 18 are electrically connected to form the input electrode 28c and the output electrode 29c, and the input electrode 28c and the output electrode 29c are electrically connected to the third spiral coil 27. 3 constitutes the input electrode 28c and the output electrode 29c of the spiral coil 27.
[0009]
As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
[0010]
[Patent Document 1]
JP-A-11-186056
[Problems to be solved by the invention]
However, in the above-described conventional noise filter, all the coils, that is, the structures of the first helical coil 9, the second helical coil 18, and the third helical coil 27 are each independently helical. Therefore, the number of layers increases, and as a result, the coupling coefficient between the first spiral coil 9 and the second spiral coil 18 and the coupling coefficient between the second spiral coil 18 and the third spiral coil 27 However, there is a limit in increasing the height of the first spiral coil 9 and the third spiral coil 27 have almost no coupling.
[0012]
An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a noise filter capable of increasing a common mode impedance value and having high common mode noise removal characteristics.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has the following configuration.
[0014]
According to the first aspect of the present invention, there is provided a magnetic body, a first coil, a second coil, and a third coil provided in the magnetic body, the first coil, the second coil, An external electrode electrically connected to both ends of the third coil, wherein the first coil is electrically connected to a spiral first conductor and the first conductor; And a second conductor formed in a spiral shape above the first conductor, and the third coil is formed in a spiral shape so as to face above the second conductor. 5 conductor, and a sixth conductor electrically connected to the fifth conductor and formed in a spiral shape above the fifth conductor. A third conductor formed in a double spiral on the same plane as the first conductor; And the fourth conductor which is electrically connected to the second conductor and is formed in a double spiral shape on the same plane as the sixth conductor. According to this configuration, the first conductor Since the coupling coefficient between the coil and the second coil, the coupling coefficient between the second coil and the third coil, and the coupling coefficient between the third coil and the first coil are all high, the number of layers is also small. The function and effect of providing a three-line noise filter having a high coupling coefficient with only four layers can be obtained.
[0015]
In particular, the invention described in claim 2 of the present invention is particularly applicable to the case where the length of the conductor between the external electrodes of the first coil, the length of the conductor between the external electrodes of the second coil, and the distance between the external electrodes of the third coil. In this configuration, the effect of providing a three-line noise filter with a balanced DC resistance can be obtained.
[0016]
In the invention according to claim 3 of the present invention, in particular, the distance between the first conductor and the third conductor and the distance between the fourth conductor and the sixth conductor are each longer than 30 μm and more than 150 μm. According to this configuration, a three-line noise filter having a high coupling coefficient can be provided.
[0017]
The invention described in claim 4 of the present invention is the one in which the distance between the first conductor and the third conductor is the same as the distance between the fourth conductor and the sixth conductor, and According to this, the effect of providing a three-line noise filter with balanced coupling coefficients can be obtained.
[0018]
In the invention according to claim 5 of the present invention, particularly, the distance between the surface on which the second conductor is formed and the surface on which the fifth conductor is formed is such that the second conductor is formed. The distance between the surface on which the third conductor is formed and the distance between the surface on which the fourth conductor is formed and the surface on which the fifth conductor is formed; According to this configuration, it is possible to obtain an operation and effect that a three-line noise filter having a balanced coupling coefficient can be provided.
[0019]
In the invention according to claim 6 of the present invention, the first coil, the second coil, and the third coil are formed by electroforming, respectively. The effect of being able to provide a line noise filter is obtained.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a noise filter according to an embodiment of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is an exploded perspective view of a noise filter according to an embodiment of the present invention, and FIG. 2 is a perspective view of the noise filter.
[0022]
1 and 2, reference numeral 31 denotes a first coil. The first coil 31 has a spiral first conductor 32 and a spiral first conductor 32 formed above the first conductor 32. And two conductors 33. The first conductor 32 has a first lead portion 32a and a first via electrode 32b located inside the spiral, and the second conductor 33 has a second lead portion 33a and a spiral lead. And a second via electrode 33b located inside.
[0023]
Reference numeral 34 denotes a second coil. The second coil 34 includes a spiral third conductor 35 and a spiral fourth conductor 36 formed above the third conductor 35. Have been. The third conductor 35 has a third lead portion 35a and a third via electrode 35b located inside the spiral, and the fourth conductor 36 has a fourth lead portion 36a and a spiral And a fourth via electrode 36b located inside.
[0024]
Reference numeral 37 denotes a third coil. The third coil 37 includes a fifth spiral conductor 38 and a sixth spiral conductor 39 formed above the fifth conductor 38. Have been. The fifth conductor 38 has a fifth lead portion 38a and a fifth via electrode 38b located inside the spiral, and the sixth conductor 39 has a sixth lead portion 39a and a spiral lead. And a sixth via electrode 39b located inside.
[0025]
Numeral 40 is a first magnetic material sheet having a rectangular shape. The first magnetic material sheet 40 is disposed between the first conductor 32 and the second conductor 33, and has a first via hole 40a. And a second via hole 40b. The first via electrode 32b and the second via electrode 33b are electrically connected to each other by the first via hole 40a, whereby the first conductor 32 and the second conductor 33 are electrically connected to each other. To form a first coil 31.
[0026]
Reference numeral 41 denotes a second magnetic material sheet having a square shape. The second magnetic material sheet 41 is disposed between the second conductor 33 and the fifth conductor 38 and has a third via hole 41a. have. The second conductor 33 insulates the second conductor 33 and the fifth conductor 38 from each other.
[0027]
Reference numeral 42 denotes a third magnetic sheet having a square shape. The third magnetic sheet 42 is disposed between the fifth conductor 38 and the sixth conductor 39 and has a fourth via hole 42a. And a fifth via hole 42b. Then, the third via electrode 35b and the fourth via electrode 36b are electrically connected to each other by the fourth via hole 42a, the second via hole 40b, and the third via hole 41a. Accordingly, the third conductor 35 and the fourth conductor 36 are electrically connected to form the second coil 34. Further, the fifth via electrode 38b and the sixth via electrode 39b are electrically connected to each other by the fifth via hole 42b, so that the fifth conductor 38 and the sixth conductor 39 are electrically connected to each other. To form a third coil 37.
[0028]
The first conductor 32, the second conductor 33, the third conductor 35, the fourth conductor 36, the fifth conductor 38, and the sixth conductor 39 are each made of a conductor such as silver. The length, width, and thickness may be adjusted to match predetermined characteristics.
[0029]
The second conductor 33 and the fifth conductor 38 face each other and are insulated by a second magnetic sheet 41 therebetween. Further, the first conductor 32 and the third conductor 35, the second conductor 33 and the fifth conductor 38, and the fourth conductor 36 and the sixth conductor 39 are extended in the same direction. When a current flows from the second lead portion 33a, the fourth lead portion 36a, and the sixth lead portion 39a from the lead portion 32a, the third lead portion 35a, and the fifth lead portion 38a, the fourth conductor It is formed such that current flows in the same direction from above or from above the sixth conductor 39 in plan view.
[0030]
By forming the first conductor 32, the second conductor 33, the third conductor 35, the fourth conductor 36, the fifth conductor 38, and the sixth conductor 39 so as to have the above arrangement relationship. Since the first conductor 32 and the third conductor 35 are formed in a double spiral shape on the same plane, if a current in the same direction flows through the first conductor 32 and the third conductor 35, The magnetic fluxes generated in the first conductor 32 and the third conductor 35 can be mutually strengthened, and as a result, the effect of increasing the common mode impedance value can be obtained.
[0031]
Further, the second conductor 33 and the fifth conductor 38 are formed in a spiral shape so as to face each other with the second magnetic material sheet 41 interposed therebetween. When the current flows in the same direction, the magnetic fluxes generated in the second conductor 33 and the fifth conductor 38 can be mutually strengthened, and the effect that the impedance value of the common mode can be increased can be obtained. It is something that can be done.
[0032]
Reference numeral 43 denotes a fourth magnetic material sheet having a rectangular shape. The fourth magnetic material sheet 43 is provided on the lower surfaces of the first conductor 32 and the third conductor 35.
[0033]
Reference numeral 44 denotes a fifth magnetic sheet having a square shape. The fifth magnetic sheet 44 is provided on the upper surfaces of the fourth conductor 36 and the sixth conductor 39.
[0034]
The first magnetic sheet 40, the second magnetic sheet 41, the third magnetic sheet 42, the fourth magnetic sheet 43, and the fifth magnetic sheet 44 are made of ferrite powder oxide. As shown in FIG. 2, a plate-shaped magnetic body 45 having a square shape is formed by stacking these in the vertical direction as described above. Note that the magnetic body 45 may not have a plate shape but have a certain thickness. Further, the magnetic body 45 does not necessarily have to be rectangular. The first magnetic sheet 40, the second magnetic sheet 41, the third magnetic sheet 42, the fourth magnetic sheet 43, and the fifth magnetic sheet 44 constituting the magnetic body 45. Each thickness may be appropriately adjusted according to predetermined characteristics (such as withstand voltage), and the thickness is adjusted by changing the thickness of the magnetic material sheet itself or by changing the number of a plurality of magnetic material sheets.
[0035]
46a, 46b and 46c are external electrodes formed on one end face of the magnetic body 45, and 47a, 47b and 47c are formed on the other end face of the magnetic body 45 so as to face the external electrodes 46a, 46b and 46c. External electrodes. These external electrodes 46a, 46b, 46c, 47a, 47b, 47c are formed by plating a surface of a conductor such as silver with a low melting point metal such as nickel or tin or solder.
[0036]
Both ends of the first coil 31, that is, the first lead portion 32 a and the second lead portion 33 a, are such that the first lead portion 32 a is the external electrode 46 a and the second lead portion 33 a is the external electrode 47 a Are electrically connected to each other. In addition, both end portions of the second coil 34, that is, the third lead portion 35a and the fourth lead portion 36a are such that the third lead portion 35a is connected to the external electrode 46b, and the fourth lead portion 36a is connected to the external electrode 47b. Each is electrically connected. In addition, both ends of the third coil 37, that is, the fifth lead portion 38a and the sixth lead portion 39a, have a fifth lead portion 38a with the external electrode 46c and a sixth lead portion 39a with the external electrode 47c. Are electrically connected to each other.
[0037]
If the first coil 31, the second coil 34, and the third coil 37 have the same length, the DC resistance values of the coils 31, 34, and 37 become equal, so that It does not break the balance when it is incorporated into a computer.
[0038]
The coupling coefficient between the first coil 31 and the second coil 34 and the coupling coefficient between the second coil 34 and the third coil 37 are determined by the distance between the first conductor 32 and the third conductor 35. And the distance between the fourth conductor 36 and the sixth conductor 39.
[0039]
FIG. 3 is a diagram showing the relationship between the distance between the first conductor 32 and the third conductor 35, the coupling coefficient K, and the withstand voltage of the noise filter according to the embodiment of the present invention.
[0040]
Note that the withstand voltage represents the percentage of non-defective products (those having an insulation resistance of 100 MΩ or more) when 100 V is applied between the first conductor 32 and the third conductor 35 for one minute. FIG. Shows the distance (μm) between the first conductor 32 and the third conductor 35, and the vertical axis shows the coupling coefficient K and the withstand voltage failure rate (%).
[0041]
As is clear from FIG. 3, it is understood that the distance between the first conductor 32 and the third conductor 35 should be longer than 30 μm and shorter than 150 μm. That is, with such a range, the withstand voltage between the first conductor 32 and the third conductor 35 can be maintained, and the withstand voltage failure rate can be reduced to 0%. Since the coupling coefficient with the third conductor 35 is also increased, the effect that the impedance value of the common mode can be increased can be obtained. The same can be said for the relationship between the fourth conductor 36 and the sixth conductor 39. The distance between the first conductor 32 and the third conductor 35 and the fourth If the distance between the conductor 36 and the sixth conductor 39 is made equal, the coupling coefficient between the first coil 31 and the second coil 34 and the coupling coefficient between the second coil 34 and the third coil 37 become This makes it possible to provide a common mode noise filter in which the common mode impedance is balanced.
[0042]
FIG. 4A shows the common mode impedance between the coils of the conventional noise filter, and FIG. 4B shows the common mode impedance between the coils of the noise filter according to the embodiment of the present invention. It is shown. 4 (a) and 4 (b), in the conventional noise filter, only the common mode impedance between the first coil 9 and the third coil 27 is low and not balanced. In the noise filter according to the embodiment of the present invention, all the common mode impedances are balanced, and it is understood that this is an excellent common mode noise filter.
[0043]
If the first conductor 32, the second conductor 33, the third conductor 35, the fourth conductor 36, the fifth conductor 38, and the sixth conductor 39 are each formed by electroforming, a narrow conductor can be obtained. Since the width and the fine pitch between conductor lines can be realized, the length of each of the conductors 32, 33, 35, 36, 38, and 39 can be lengthened, whereby the respective conductors 32, 33, 35, 36, and Since the magnetic fluxes generated at 38 and 39 can be further strengthened, the common mode impedance value can be further increased.
[0044]
【The invention's effect】
As described above, the noise filter of the present invention includes a magnetic body, a first coil, a second coil, and a third coil provided in the magnetic body, and the first, second, and third coils. An outer electrode electrically connected to both ends of the third coil, the first coil being a spiral first conductor, electrically connected to the first conductor, and A second conductor formed in a spiral shape above the first conductor, and the third coil is formed in a spiral shape so as to face above the second conductor. And a sixth conductor that is electrically connected to the fifth conductor and that is formed in a spiral shape above the fifth conductor. A third conductor formed in a double spiral shape on the same plane as the first conductor; The third coil is electrically connected to the third conductor, and the fourth conductor is formed in a double spiral shape on the same plane as the sixth conductor. The coupling coefficient between the second coil, the coupling coefficient between the second coil and the third coil, and the coupling coefficient between the third coil and the first coil are all high, so that the number of layers and the coil conductor This is an excellent effect that a noise filter of three lines having a high coupling coefficient can be provided with only four layers.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a noise filter according to an embodiment of the present invention. FIG. 2 is a perspective view of the noise filter. FIG. 3 is a distance between a first conductor 32 and a third conductor 35 of the noise filter. FIG. 4A is a diagram showing a relationship between a coupling coefficient K and a withstand voltage. FIG. 4A is a diagram showing a common mode impedance between coils of a conventional noise filter. FIG. 4B is a diagram showing each noise filter according to an embodiment of the present invention. FIG. 5 shows a common mode impedance between coils. FIG. 5 is an exploded perspective view of a conventional noise filter.
31 first coil 32 first conductor 33 second conductor 34 second coil 35 third conductor 36 fourth conductor 37 third coil 38 fifth conductor 39 sixth conductor 40 first magnetism Body sheet 41 Second magnetic body sheet 42 Third magnetic body sheet 43 Fourth magnetic body sheet 44 Fifth magnetic body sheet 45 Magnetic bodies 46a to 46c, 47a to 47c External electrodes

Claims

A magnetic body, a first coil, a second coil, and a third coil provided in the magnetic body; and both ends of the first coil, the second coil, and the third coil. And an external electrode connected to the first coil, wherein the first coil is spirally connected to the first conductor and is formed in a spiral shape above the first conductor. The third coil is composed of a fifth conductor which is formed in a spiral shape facing the second conductor, and which is electrically connected to the fifth conductor. And a sixth conductor that is spirally formed above the fifth conductor, and the second coil is a double coil on the same plane as the first conductor. A third conductor formed in a spiral shape, and electrically connected to the third conductor, and Serial sixth fourth noise filter constituted by a conductor formed in a double spiral on the conductor flush with.

The length of the conductor between the external electrodes of the first coil, the length of the conductor between the external electrodes of the second coil, and the length of the conductor between the external electrodes of the third coil are the same. 2. The noise filter according to 1.

The noise filter according to claim 1, wherein a distance between the first conductor and the third conductor and a distance between the fourth conductor and the sixth conductor are longer than 30 µm and shorter than 150 µm, respectively.

The noise filter according to claim 1, wherein a distance between the first conductor and the third conductor is equal to a distance between the fourth conductor and the sixth conductor.

The distance between the surface on which the second conductor is formed and the surface on which the fifth conductor is formed is defined as the distance between the surface on which the second conductor is formed and the surface on which the third conductor is formed. 2. The noise filter according to claim 1, wherein the distance is shorter than any of a distance and a distance between a surface on which the fourth conductor is formed and a surface on which the fifth conductor is formed.

The noise filter according to claim 1, wherein the first coil, the second coil, and the third coil are each formed by electroforming.