JP3974773B2 - Magnetic core having magnet for magnetic bias and inductance component using the same - Google Patents

Description

【００４２】
表１から、被覆処理温度が６５０℃と６００℃のデータからわかるように、被覆処理温度が６００℃を超えると表面磁束が小さくなる事がわかる。コアロスについては被覆処理温度が４００℃すなわち軟化点が３５０℃のガラス組成の被覆を用いたものは、リフロー後に表面磁束が劣化することがわかった。これは、南下点が３５０℃のガラス粉末は、一旦被覆処理された後、樹脂との熱混練中に再融解してはがれたことによるものと考えられる。他方、軟化点が６００℃を超えるガラスについては被覆処理温度が高すぎて、磁石粉末の酸化または被覆ガラス材との反応により磁石粉末の磁化寄与分の減少が起こって減磁が生じたものと思われる。
【００４３】
次に、コイル（図２の３５で示す）に直流磁界として８０（Ｏｅ）となる直流を重畳しながら、交流信号を印加した時のインダクタンスＬをＬＣＲメーターで測定し、コア定数（寸法）とコイルの巻線数から透磁率を計算した。その結果は、軟化点が４００℃（ＺｎＯ−Ｂ_２Ｏ_３−ＰｂＯ（２））〜５５０℃（ＳｉＯ_２−Ｂ_２Ｏ_３−ＰｂＯ（１））のガラス粉末を用いて被覆した磁石粉末を含むボンド磁石を磁気ギャップに挿入配置したコアの透磁率は５０以上の値を示した。一方、比較例として、磁気ギャップに磁石を挿入配置しない場合のコアの透磁率、及び、軟化点が３５０℃のガラス粉末（ＺｎＯ−Ｂ_２Ｏ_３−ＰｂＯ（１））及び６００℃のガラス粉末（ＳｉＯ_２−Ｂ_２Ｏ_３−ＰｂＯ（２））で被覆した磁石粉末を含むボンド磁石を磁気ギャップに挿入配置したコアの透磁率は、いずれも１５と著しく低い値を示した。
【００４４】
以上の結果より、軟化点が４００℃以上で５５０℃以下のガラス粉末で被覆した磁石粉末を用いたボンド磁石であって、比抵抗が１Ω・ｃｍ以上の永久磁石を磁気コアの磁気ギャップに挿入配置する時、直流重畳特性に優れしかもコアロス特性の劣化が小さい優れた磁気コアが得られる事が分かった。
【００４５】
（第２の実施の形態）
第１の実施の形態で使用したＳｍ_２Ｃｏ_１７磁石粉末と、軟化点が約５００℃の約３μｍのＳｉＯ_２−Ｂ_２Ｏ_３−ＰｂＯガラス粉末を、後者の重量比が、０．１、０．５、１．０、２．５、５．０、７．５、１０、１２．５ｗｔ％となるように、それぞれ、混合し、５５０℃Ａｒ中で熱処理して、磁石粉末にガラス被覆処理をした。次にこれらガラス被覆処理をした磁石粉末に、バインダーＺｎＯ−Ｂ_２Ｏ_３−ＰｂＯ（２））としてポリイミド樹脂を体積比で５０ｖｏｌ％混合して、ドクターブレード法でシート状にした。その溶剤を乾燥後、熱プレスし、厚み０．５ｍｍに成形した。
【００４６】
このボンド磁石の磁気特性は、テストピースを別途作製し、第１の実施の形態と同様にして測定した。その結果、各ボンド磁石は、磁石粉末に混合したガラス粉末の量によらず全て約１０ＫＯｅ以上の固有保磁力を示した。また比抵抗を測定した結果、全てのボンド磁石について１Ω・ｃｍ以上の値を示した。
【００４７】
次に第１の実施の形態と全く同様にシート状ボンド磁石を着磁して、その表面磁束を測定後、図１および２に示すフェライトのＥＥコア３３の中央磁脚の磁気ギャップに挟み込み、第１の実施の形態と同様に、コイル３５に交流と直流を重畳して印加し、直流重畳特性を測定した。さらに、第１の実施の形態と全く同様のリフロー炉（最高温度２７０℃）に２回通し、再度表面磁束と直流重畳特性を測定した。その結果を表面磁束については表２に、直流重畳特性については表３に示す。
【００４８】
【表２】

【００４９】
【表３】

【００５０】
表２および表３に示す通り、ガラス粉末の添加量が実質的に０を超え１０ｗｔ％以下の時優れた特性の耐酸化性の磁石が得られる事が分かる。
【００５１】
以上に説明したように、磁路の少なくとも１箇所以上にギャップを有する磁気コアであって、その磁気ギャップに挿入配置する磁気バイアス用磁石を、固有保磁力ｉＨｃが１０ＫＯｅ以上、キュリー点Ｔｃが５００℃以上、粉末粒径が２．５〜５０μｍの希土類磁石粉末を用いたボンド磁石とし、その磁石粉末表面を無機ガラスで被覆し、その粉末と少なくとも体積比で３０％以上の樹脂からなる比抵抗が１Ωｃｍ以上のボンド磁石を用いることによって、直流重畳特性、コアロス特性、耐酸化性に優れた磁気コアを実現できる。
【００５２】
次に本発明のもう一つの発明について説明する。
【００５３】
本発明の第２発明では、磁路の少なくとも１箇所以上にギャップを有する磁気コアに、該ギャップ両端から磁気バイアスを供給するために、該ギャップ近傍に永久磁石を配してなる磁気バイアス用磁石を有する磁気コアにおける上記課題を解決するために、前記永久磁石が、５ＫＯｅ以上の固有保磁力及び３００℃以上のキュリー温度を持つ粉末平均粒径が２．０〜５０μｍの希土類磁石粉末と樹脂とからなるボンド磁石であり、前記磁石粉末を無機ガラスで被覆した磁気バイアス用磁石を有する磁気コアである。
【００５４】
前記磁気バイアス用磁石としてのボンド磁石は、前記樹脂を体積比で３０％以上含有し、比抵抗が１Ωｃｍ以上であることが好ましい。
【００５５】
前記無機ガラスは、軟化点が２００℃以上５５０℃以下であることが好ましい。
【００５６】
また、前記ボンド磁石は、前記磁石粉末を被覆する前記無機ガラスは、重量比で、１０％以下含有することが好ましい。
【００５７】
又、本発明によれば、前記の磁気バイアス用磁石を有する磁気コアに、１ターン以上の巻線を少なくともひとつ施してあることを特徴とするインダクタンス部品が得られる。
【００５８】
なお、インダクタンス部品とは、コイル、チョークコイル、トランス、その他一般に磁気コアと巻き線とを必須とした部品を含むものとする。
【００５９】
本発明は、前記課題を達成するべく挿入する永久磁石について検討した結果、磁石の比抵抗が１Ωｃｍ以上で、固有保磁力ｉＨｃが５ＫＯｅ以上の永久磁石を使用するとき優れた直流重畳特性が得られ、しかもコアロス特性の劣化が生じない磁気コアを形成できる事を発見したものである。これは、優れた直流重畳特性を得るのに必要な磁石特性はエネルギー積よりもむしろ固有保磁力であり、従ってエネルギー積の低い永久磁石を使用しても固有保磁力が高ければ充分に高い直流重畳特性が得られる事を見出したことによる。
【００６０】
比抵抗が高くしかも固有保磁力が高い磁石は、一般的には希土類磁石粉末をバインダーとともに混合して成形した希土類ボンド磁石で得られるが、保磁力の高い磁石粉末であればどのような組成のものでも可能である。希土類磁石粉末の種類はＳｍＣｏ系、ＮｄＦｅＢ系、ＳｍＦｅＮ系とある。
【００６１】
チョークコイル用及びトランス用磁気コアとしては、軟磁気特性を有する材料であればなんでも有効であるが、一般的にはＭｎＺｎ系又はＮｉＺｎ系フェライト、圧粉磁気コア、珪素鋼板、アモルファス等が用いられる。また、磁気コアの形状についても特に制限があるわけではなく、トロイダルコア、ＥＥコア、ＥＩコア等あらゆる形状の磁気コアに本発明の適用が可能である。これらコアの磁路の少なくとも１箇所以上にギャップを設け、そのギャップに永久磁石を挿入配置する。
【００６２】
ギャップ長に特に制限はないがギャップ長が狭すぎると直流重畳特性が劣化し、またギャップ長が広すぎると透磁率が低下しすぎるので、おのずから挿入するギャップ長は決まってくる。なお、磁気バイアス用永久磁石の厚みは大きければバイアス効果を容易に得られるが、磁気コアの小型化にとっては、磁気バイアス用永久磁石は、薄いほどよい。しかしながら、５０μｍより小さいと十分な磁気バイアスが得られない。したがって、磁気バイアス用永久磁石を配置する磁気ギャップは５０μｍ以上であることが必要であり、コア寸法を抑えるという点からは、１００００μｍ以下が好ましい。
【００６３】
次にギャップに挿入される永久磁石に対する要求特性は、固有保磁力については５ＫＯｅ以下では磁気コアに印可される直流磁界によって保磁力が消失するのでそれ以上の保磁力が必要であり、また比抵抗は大きいほど良いが１Ω・ｃｍ以上であればコアロス劣化の大きな要因にはならない。また、粉末の平均最大粒径が５０μｍ以上になるとコアロス特性が劣化するので、粉末の最大粒径は５０μｍ以下である事が望ましく、最小粒径が２．０μｍ以下になると粉砕による粉末酸化により磁化の減少が顕著になるため２．０μｍ以上の粒径が必要で有る。
【００６４】
またコイルの発熱による熱減磁の問題があるが、トランスの想定される最高使用温度は２００℃なのでＴｃが３００℃以上であれば実質的に問題とはならない。また、コアロスを増大させないため樹脂の量は少なくとも体積比で２０％以上必要であり、耐酸化性を増大させるための無機ガラスは軟化点が２５０℃以上であれば最高使用温度でもその被覆が破壊されることがなく、一方５５０℃以下であればコーティング熱処理時の粉末酸化の問題が顕著には現れない。また、無機ガラスを添加することによって耐酸化性の効果があるが、添加量が１０ｗｔ％を超えると非磁性物の量の増加により、直流重畳特性の改善が小さくなるので、上限を１０ｗｔ％とするのがよい。
【００６５】
以下、本第２発明の実施の形態について、説明する。
【００６６】
（第３の実施の形態）
ガラス粉末として、軟化点が約３５０℃のＺｎＯ−Ｂ_２Ｏ_３−ＰｂＯ（１）、軟化点が約４００℃のＺｎＯ−Ｂ_２Ｏ_３−ＰｂＯ（２）、軟化点が約４５０℃のＢ２Ｏ３−ＰｂＯ、軟化点が約５００℃のＫ_２Ｏ−ＳｉＯ_２−ＰｂＯ、軟化点が約５５０℃のＳｉＯ_２−Ｂ_２Ｏ_３−ＰｂＯ（１）、軟化点が約６００℃のＳｉＯ２−Ｂ２Ｏ３−ＰｂＯ（２）、の６種類のガラス粉末を用意した。各粉末は、粒径が約３μｍであった。
【００６７】
次にＳｍ_２Ｃｏ_１７磁石粉末として、インゴットを粉砕して一般的な粉末冶金法で作製した焼結体を２．３μｍに微粉砕したものを用意した。その磁石粉末の磁気特性をＶＳＭで測定した結果は、保磁力ｉＨｃが約９ＫＯｅであった。
【００６８】
この磁石粉末に前記した各々のガラス粉末を１％混合し、ガラス粉末の軟化点よりも約５０℃高い温度にてＡｒ中で熱処理することによって、磁石粉末の表面をガラスにて被覆した。次にこうして被覆処理した磁石粉末と、体積比で４５ｖｏｌ％の熱可塑性樹脂として６ナイロンとを２軸式の熱混練機によって２２０℃にて混練した。次に熱プレス機で成形温度２２０℃、圧力０．０５ｔ／ｃｍ^２で高さ１．５ｍｍのシート状に無磁場中で成形し、ボンド磁石を作製した。これらシート状ボンド磁石の比抵抗は全て１Ωｃｍ以上の値を示した。このシート状ボンド磁石は図１および図２に示すものと同様のフェライトコア３３の中央磁脚と同一断面形状に加工した。
【００６９】
ここでボンド磁石の磁石特性は、作製したボンド磁石のシートを必要枚数張り合わせる事により直径φ１０ｍｍで厚みｔ１０ｍｍのテストピースを別途作製し、直流ＢＨトレーサーで測定した。その結果、全てのボンド磁石について固有保磁力が約９ＫＯｅ得られている事が分かった。
【００７０】
フェライトコア３３は、一般的なＭｎＺｎ系フェライト材で作製された磁路長７．５ｃｍ、実効断面積０．７４ｃｍのＥＥコアで、その中央磁脚に１．５ｍｍのギャップ加工を施した。そのギャップ部に、上記作製したボンド磁石３１を着磁磁場４Ｔでパルス着磁後、ガウスメーターで表面磁束を測定後、挿入配置した。次に、岩崎通信機製のＳＹ−８２３２交流ＢＨトレーサーで１００ＫＨｚ、０．１Ｔにおけるコアロス特性を室温で測定した。ここで測定に使用したフェライトコアは、各ボンド磁石に対して、同一のものであり、被覆されたガラスの種類だけが異なる磁石３１を交換して、コアロスを測定した。その測定結果を、表４に、熱処理前として示す。次に、それらボンド磁石をトランスの想定される最高使用温度である２００℃の恒温槽に正味３０分間保持し、上記と全く同様に表面磁束とコアロスを測定し、表４に、熱処理後として示す。
【００７１】
【表４】

【００７２】
表４から、被覆処理温度が６５０℃と６００℃のデータからわかるように、被覆処理温度が６００℃を超えると表面磁束が小さくなる事がわかる。コアロスについてはどのガラス組成の被覆を用いた場合でも劣化は見られなかった。従って、軟化点が６００℃を超えるガラスについては被覆処理温度が高すぎて、磁石粉末の酸化または被覆ガラス材との反応により磁石粉末の磁化寄与分の減少が起こって減磁が生じたものと思われる。
【００７３】
次に、コイル（図２の３５５で示す）に直流磁界として８０（Ｏｅ）となる直流を重畳品から、交流信号を印加して時のインダクタンスＬをＬＣＲメーターで測定し、コア定数（寸法）とコイルの巻線数から透磁率を計算した。その結果は、軟化点が３５０℃（ＺｎＯ−Ｂ_２Ｏ_３−ＰｂＯ（１））〜５５０℃（ＳｉＯ_２−Ｂ_２Ｏ_３−ＰｂＯ（１））のガラス粉末を用いて被覆した磁石粉末を含むボンド磁石を磁気ギャップに挿入配置したコアの透磁率は５０以上の値を示した。一方、比較例として、磁気ギャップに磁石を挿入配置しない場合のコアの透磁率、及び、軟化点が６００℃のガラス粉末（ＳｉＯ_２−Ｂ_２Ｏ_３−ＰｂＯ（２））で被覆した磁石粉末を含むボンド磁石を磁気ギャップに挿入配置したコアの透磁率は、いずれも１５と著しく低い値を示した。
【００７４】
以上の結果より、ガラス粉末の軟化点が５５０℃以下のガラス粉末で被覆した磁石粉末を用いたボンド磁石であって、比抵抗が１Ω・ｃｍ以上の永久磁石を磁気コアの磁気ギャップに挿入配置する時、直流重畳特性に優れしかもコアロス特性の劣化が小さい優れた磁気コアが得られる事が分かった。
【００７５】
（第４の実施の形態）
磁石粉末として還元拡散法で作製されたＳｍＦｅ粉末を３μｍに微粉砕後、窒化処理する事で得られたＳｍＦｅＮ粉末を用意した。この磁石粉末の磁気特性をＶＳＭで測定した結果は、保磁力ｉＨｃが約８ＫＯｅであった。
【００７６】
次に、この磁石粉末と、軟化点が約３５０℃の約３μｍのＺｎＯ−Ｂ_２Ｏ_３−ＰｂＯ ガラス粉末を、後者の重量比が、０．１、０．５、１．０、２．５、５．０、７．５、１０、１２．５ｗｔ％となるように、それぞれ、混合し、４００℃Ａｒ中で熱処理して、磁石粉末にガラス被覆処理をした。次にこれらガラス被覆処理をした磁石粉末に、バインダーとしてエポキシ樹脂を体積比で３０ｖｏｌ％混合して、図１及び２に示すフェライトコア３３の中央磁脚と同一の断面形状のシート状に金型成形後、１５０℃で樹脂を硬化させ、ボンド磁石を形成した。このボンド磁石の磁気特性は、テストピースを別途作製し、第３の実施の形態と同様にして測定した。その結果、各ボンド磁石は、磁石粉末に混合したガラス粉末の量によらず全て約８ＫＯｅの固有保磁力を示した。また比抵抗を測定した結果、全てのボンド磁石について１Ω・ｃｍ以上の値を示した。
【００７７】
次に第３の実施の形態と全く同様にシート状ボンド磁石を着磁して、その表面磁束を測定後、図１および２に示すフェライトのＥＥコア３３の中央磁脚の磁気ギャップに挟み込み、第３の実施の形態と同様に、コイル３５に交流と直流を重畳して印加し、直流重畳特性を測定した。
【００７８】
さらに、第３の実施の形態と全く同様に２００℃恒温槽に実質的に３０分間保持し、再度表面磁束と直流重畳特性を測定した。その結果を表面磁束については表５に、直流重畳特性については表６に示す。
【００７９】
【表５】

【００８０】
【表６】

【００８１】
表５および表６に示す通り、ガラス粉末の添加量が実質的に０を超え１０ｗｔ％以下の時優れた特性の耐酸化性の磁石が得られる事が分かる。
【００８２】
以上に説明したように、本発明の第２発明によれば、磁路の少なくとも１箇所以上にギャップを有する磁気コアであって、その磁気ギャップに挿入配置する磁気バイアス用磁石を、固有保磁力ｉＨｃが５ＫＯｅ以上、キュリー点Ｔｃが３００℃以上、粉末粒径が２．０〜５０μｍの希土類磁石粉末を用いたボンド磁石とし、その磁石粉末表面を無機ガラスで被覆し、その粉末と少なくとも体積比で２０％以上の樹脂からなる比抵抗が１Ωｃｍ以上のボンド磁石を用いることによって、直流重畳特性、コアロス特性、耐酸化性に優れた磁気コアを実現できる。
【００８３】
次に本発明のさらにもう一つの発明について説明する。
【００８４】
本発明の第３発明では、ポリアミドイミド樹脂、ポリイミド樹脂、エポキシ樹脂、ポリフェニレンサルファイト樹脂、シリコン樹脂、ポリエステル樹脂、芳香族系ポリアミド、液晶ポリマーから選択された一種類の樹脂に磁石粉末が分散されてなり、該樹脂含有量が体積比で３０％以上で、全体の厚みが５００μｍ以下であることを特徴とする薄板磁石が得られる。
【００８５】
ここで、前記磁石粉末は、固有保磁力が１０ＫＯｅ以上、Ｔｃが５００℃以上、粉末平均粒径が２．５〜５０μｍであることが好ましい。
【００８６】
また、薄板磁石においては、前記磁石粉末は、希土類磁石粉末であり、また、表面のグロス（光沢度）が２５％以上であることが好ましい。
【００８７】
また、薄板磁石においては、成形圧縮率が２０％以上であることが好ましい。前記磁石粉末は、表面活性剤でコーティングされている。
【００８８】
又、本発明の薄板磁石において、比抵抗が０．１Ω・ｃｍ以上あることが好ましい。
【００８９】
又、本発明においては、磁路の少なくとも１箇所以上に磁気ギャップを有する磁気コアに、該ギャップ両端から磁気バイアスを供給するために、該磁気ギャップ近傍に永久磁石を配してなる磁気バイアス用磁石を有する磁気コアにおいて、前記永久磁石が、前記した薄板磁石である磁気バイアス用磁石を有する磁気コアである。
【００９０】
前記磁気ギャップは、約５００μｍ以下のギャップ長を有し、前記磁気バイアス用磁石は該ギャップ長以下の厚みを有し、厚み方向に磁化されていることが好ましい。
【００９１】
更に又、本発明のインダクタンス部品は、前記薄板磁石を磁気バイアス用磁石として備えた磁気コアに、１ターン以上の巻線を少なくともひとつ施して、薄型で、直流重畳特性が良好で、コアロス低いインダクタンス部品である。
【００９２】
即ち、本発明においては、磁気コアの磁気ギャップに挿入配置する磁気バイアス用の永久磁石として、５００μｍ以下の厚みの薄板磁石の可能性について検討した。その結果、特定樹脂の含有量が体積比で３０％以上の薄板磁石の比抵抗が０．１Ω・ｃｍ以上で固有保磁力が１０ＫＯｅ以上の薄板磁石を使用した時優れた直流重畳特性が得られ、しかもコアロス特性の劣化が生じない磁気コアを形成できる事を発見した。これは、優れた直流重畳特性を得るのに必要な磁石特性は、エネルギー積よりもむしろ固有保磁力であり、従って比抵抗の高い永久磁石を使用しても固有保磁力が高ければ充分に高い直流重畳特性が得られる事を見出したことによる。
【００９３】
比抵抗が高くしかも固有保磁力が高い磁石は、一般的には希土類磁石粉末をバインダーとともに混合して成形した希土類ボンド磁石で得られるが、保磁力の高い磁石粉末であればどのような組成のものでも可能である。希土類磁石粉末の種類はＳｍＣｏ系、ＮｄＦｅＢ系、ＳｍＦｅＮ系とあるが、リフロー等の使用時の熱減磁を考えるとキュリー点Ｔｃが５００℃以上、固有保磁力ｉＨｃが１０ＫＯｅ以上の磁石が必要である。
【００９４】
また、磁石粉末に表面活性材でコーティングすることにより成形体中での粉末の分散が良好となり磁石の特性が向上するためさらに高特性の磁気コアが得られる。
【００９５】
チョークコイル用及びトランス用磁気コアとしては軟磁気特性を有する材料であればなんでも有効であるが、一般的にはＭｎＺｎ系又はＮｉＺｎ系フェライト、圧粉磁気コア、珪素鋼板、アモルファス等が用いられる。また、磁気コアの形状についても特に制限があるわけではなく、トロイダルコア、ＥＥコア、ＥＩコア等あらゆる形状の磁気コアに本発明の適用が可能である。これらコアの磁路の少なくとも１箇所以上にギャップを設け、そのギャップに薄板磁石を挿入配置する。ギャップ長に特に制限はないがギャップ長が狭すぎると直流重畳特性が劣化し、またギャップ長が広すぎると透磁率が低下しすぎるので、おのずから挿入するギャップ長は決まってくる。磁気コア全体の寸法を小さくするために、ギャップ長を５００μｍに抑える。
【００９６】
次にギャップに挿入される薄板磁石に対する要求特性は、固有保磁力については１０ＫＯｅ以下では磁気コアに印可される直流重畳磁界によって保磁力が消失するのでそれ以上の保磁力が必要であり、また比抵抗は大きいほど良いが０．１Ω・ｃｍ以上であればコアロス劣化の大きな要因にはならない。また、粉末の平均最大粒径が５０μｍ以上になるとコアロス特性が劣化するので、粉末の最大粒径は５０μｍ以下である事が望ましく、最小粒径が２．５μｍ以下になると粉末熱処理及びリフロー時に粉末の酸化による磁化の減少が顕著になるため２．５μｍ以上の粒径が必要で有る。
【００９７】
以下、本第３発明の実施の形態について説明する。
【００９８】
（第５の実施の形態）
Ｓｍ_２Ｃｏ_１７磁石粉末とポリイミド樹脂を熱混練機としてラボプラストミルを用いて熱混練を行った。樹脂量としては１５ｖｏｌ％〜４０ｖｏｌ％で変化させそれぞれ混練した。熱混練で得たものを熱プレス機で０．５ｍｍの薄板磁石の成形を試みた。この結果、樹脂の添加量は３０ｖｏｌ％以上でないと成形できないことがわかった。また、本実施の形態ではポリイミド樹脂薄板磁石の結果を示したが、これ以外のエポキシ樹脂、ポリフェニレンサルファイト樹脂、シリコン樹脂、ポリエステル樹脂、芳香族系ポリアミド、液晶ポリマーのそれぞれにおいても、同様の結果が得られた。
【００９９】
（第６の実施の形態）
各磁石粉末と各種樹脂とを、それぞれ、下の表７に示す組成でラボプラストミルを用いて熱混練を行った。ラボプラストミルの運転時の設定温度は各樹脂の軟化点よりもそれぞれ５℃高い温度とした。
【０１００】
【表７】

【０１０１】
ラボプラストミルで混練したものを、熱プレス機で無磁場中で金型成形する事によりそれぞれ０．５ｍｍの薄板磁石を作製した。この薄板磁石を図１，図２に示すＥ型フェライトコア３３の中央磁脚と同一断面形状に切断した。
【０１０２】
次に、図１，図２に示すように、一般的なＭｎＺｎ系フェライト材で作製された磁路長７．５ｃｍ、実効断面積０．７４ｃｍのＥＥコアの中央磁脚に０．５ｍｍのギャップ加工をした。そのギャップ部に上記作製した薄板磁石３１を挿入配置して、磁気バイアス磁石３１を有する磁気コアを作製した。同図において、３１が薄板磁石、３３がフェライトコアである。次に、磁石３１を、パルス着磁機でコア３３の磁路方向に着磁後、コア３３にコイル３５を巻き線し、ＨＰ製−４２８４ＬＣＲメーターで、交流磁場周波数１００ｋＨｚ、重畳磁場０〜２００Ｏｅの条件で、インダクタンスＬを測定した。この測定後、２７０℃でリフロー炉で３０分保持した後、インダクタンスＬを再び測定し、この繰り返しで５回測定した。この時の直流重畳による磁界の向きが、磁気バイアス磁石の磁化の向きとは逆になるように直流重畳電流を印可する。得られたインダクタンスＬと、コア定数（コア寸法等）と巻線数から透磁率を計算して、直流重畳特性を得た。各コアの５回の測定に基づく直流重畳特性を図３〜図７に示す。
【０１０３】
図７から、Ｓｍ_２Ｃｏ_１７磁石粉末をポリプロピレン樹脂に分散した薄板磁石を挿入配置したコアは２回目以降直流重畳特性が大きく劣化していることがわかる。これは、リフローで薄板磁石が変形してしまった為である。保磁力が４ｋＯｅしかないＢａフェライトをポリイミド樹脂に分散した薄板磁石を挿入配置したコアでは、図６に見られるように、測定回数がすすむにつれ、直流重畳特性が大きく劣化することがわかる。逆に、保磁力が１０ｋＯｅ以上の磁石粉末とポリイミドあるいはエポキシ樹脂とを用いた薄板磁石を挿入配置したコアは、図３〜８に見られる通り、繰り返しの測定においても大きな変化は無く、非常に安定した特性を示すことが分かる。これらの結果よりＢａフェライト薄板磁石は保磁力が小さいために、薄板磁石に印可される逆向きの磁界によって減磁、または磁化の反転が起こり、直流重畳特性が劣化したものと推測できる。また、コアに挿入する薄板磁石は保磁力が１０ｋＯｅ以上の薄板磁石において優れた直流重畳特性を示すことが分かった。また、本実施の形態では示さなかったが、本実施の形態以外の組み合わせでもポリフェニレンサルファイト樹脂、シリコン樹脂、ポリエステル樹脂、芳香族系ポリアミド、液晶ポリマーから選択した樹脂で作製した薄板磁石においても同様の効果が得られることを確認した。
【０１０４】
（第７の実施の形態）
ポリフェニレンサルファイト樹脂３０ｖｏｌ％と、磁石粉末の粒径が１．０μｍ、２．０μｍ、２５μｍ、５０μｍ、５５μｍのＳｍ_２Ｃｏ_１７磁石粉末とを、それぞれ、ラボプラストミルを用いて熱混練を行った。ラボプラストミルで混練したものを、熱プレス機により無磁場中で金型成形する事によりそれぞれ０．５ｍｍの薄板磁石を作製した。次に、第６の実施の形態と同様に、図１及び図２に示すように、この薄板磁石３１をＥ型フェライトコア３３の中央磁脚と同一断面形状に切断し、図１及び図２に示すようなコアを作製した。次に、薄板磁石３１を、パルス着磁機でコア３３の磁路方向に着磁後、コア４５にコイル４７を巻き線し、岩崎通信機製のＳＹ−８２３２交流ＢＨトレーサーで、３００ＫＨｚ、０．１Ｔにおけるコアロス特性を室温で測定した。その測定結果を表８に示す。表８より薄板磁石に用いる磁石の粉末平均粒径が２．５〜５０μｍではコアロス特性が優れていることがわかった。
【０１０５】
【表８】

【０１０６】
（第８の実施の形態）
Ｓｍ_２Ｃｏ_１７磁石粉末６０ｖｏｌ％とポリイミド樹脂４０ｖｏｌ％とをラボプラストミルを用いてそれぞれ熱混練を行った。熱混練で得たものを熱プレス機でプレス圧を変化させ０．３ｍｍの成形体を作製し、パルス着磁装置で４Ｔで着磁を行い、薄板磁石を作製した。作製した薄板磁石のグロス（光沢度）は、それぞれ１５％〜３３％でプレス圧が高いほどグロスも高い値を示した。これらの成形体を１ｃｍ×１ｃｍに切断を行い、ＴＯＥＩ ＴＤＦ−５ Ｄｉｇｉｔａｌ Ｆｌｕｘｍｅｔｅｒでフラックスを測定した結果とグロスの測定結果を表９に並べて示す。
【０１０７】
【表９】

【０１０８】
表９の結果から、グロスが２５％以上の薄板磁石では磁石特性が優れている。これは、作製した薄板磁石のグロスが２５％以上では薄板磁石の充填率が９０％以上となるためである。また、本実施の形態ではポリイミド樹脂で実験を行った結果を示したが、これ以外のエポキシ樹脂、ポリフェニレンサルファイト樹脂、シリコン樹脂、ポリエステル樹脂、芳香族系ポリアミド、液晶ポリマーから選択された一種類の樹脂でも同様の結果が得られた。
【０１０９】
（第９の実施の形態）
乾燥後の体積比がＳｍ_２Ｃｏ_１７磁石粉末６０ｖｏｌ％、ポリイミド樹脂４０ｖｏｌ％となるように、Ｓｍ_２Ｃｏ_１７磁石粉末と新日本理化製リカコート（ポリイミド樹脂）に、溶剤としてγ−ブチロラクトンを加えて、円心脱泡機で５分攪拌後、３本ロールで混練を行ってペーストを作製した。溶剤の配合比は、Ｓｍ_２Ｃｏ_１７磁石粉末と新日本理化製リカコートを合わせて７０重量部に対してγ−ブチロラクトンを１０重量部とした。作製したペーストをドクターブレード法により５００μｍのグリーンシートを作製し乾燥を行った。乾燥させたグリーンシートを１ｃｍ×１ｃｍに切断し、プレス圧を変化させ熱プレス機で熱プレスを行い、作製した成形体をパルス着磁装置で４Ｔで着磁を行い、薄板磁石を作製した。比較として、熱プレスを行っていない成形体も着磁して薄板磁石にした。また、今回は上記の配合比で作製したが、これ以外の成分、配合比でも、グリーンシート作製可能なペーストが得られるものであれば良い。また、混練のために三本ロールミルを用いたが、これ以外にもホモジナイザーやサンドミル等を用いても良い。作製した薄板磁石のグロス（光沢度）は、それぞれ９％〜２８％でプレス圧が高いほどグロスも高い値を示した。これらの薄板磁石のフラックスをＴＯＥＩ ＴＤＦ−５ Ｄｉｇｉｔａｌ Ｆｌｕｘｍｅｔｅｒで測定した結果を表１０に示す。また、この時の薄板磁石の熱プレスによる圧縮率（＝１−熱プレス後の厚さ／熱プレス前の厚さ）を測定した結果も並べて示す。
【０１１０】
【表１０】

【０１１１】
以上の結果から、第８の実施の形態と同様に、グロスが２５％以上では良好な磁石特性が得られる。この理由もグロス２５％以上では薄板磁石の充填率が９０％以上となるためである。また、圧縮率についてみると圧縮率２０％以上で良好な磁石特性が得られることがわかった。
【０１１２】
本実施の形態ではポリイミド樹脂で上記組成、配合比で実験を行った結果を示したが、これ以外のこれ以外のエポキシ樹脂、ポリフェニレンサルファイト樹脂、シリコン樹脂、ポリエステル樹脂、芳香族系ポリアミド、液晶ポリマーから選択された一種類の樹脂及び配合比、においても同様の結果が得られた。
【０１１３】
（第１０の実施の形態）
Ｓｍ_２Ｃｏ_１７磁石粉末と、界面活性剤としてリン酸ナトリウムを０．５ｗｔ％とを混合した。同様にして、Ｓｍ_２Ｃｏ_１７磁石粉末と、カルボキシメチルセルロースナトリウム０．５ｗｔ％とを混合、Ｓｍ_２Ｃｏ_１７磁石粉末と珪酸ナトリウムとを、それぞれ混合した。これら混合した粉末の、それぞれ、６５ｖｏｌ％と、ポリフェニルサルファイト樹脂３５ｖｏｌ％とをラボプラストミルを用いてそれぞれ熱混練を行った。ラボプラストミルで混練したものを熱プレスにより０．５ｍｍに成型し、第６の実施の形態と同一の、図１及び図２に示すＥ型フェライトコア３３の中央磁脚と同一断面形状に切断し、ＥＥコア３３の中央磁脚ギャップ部に上記作製した薄板磁石３１を挿入配置し、図１及び図２に示すコアを作製した。次に、この薄板磁石３１をパルス着磁機でコア３３の磁路方向に着磁後、コア３３にコイル３５を巻き線し、岩崎通信機製のＳＹ−８２３２交流ＢＨトレーサーにて、３００ＫＨｚ、０．１Ｔにおけるコアロス特性を室温で測定した。その測定結果を表１１に示す。比較として、界面活性剤を用いずに、Ｓｍ_２Ｃｏ_１７磁石粉末６５ｖｏｌ％とポリフェニルサルファイト樹脂３５ｖｏｌ％とをラボプラストミルで混練したものを熱プレスにより０．５ｍｍに成型し、上記と同じフェライトＥＥコアの中央磁脚の磁気ギャップ中に挿入配置し、これをパルス着磁機でコアの磁路方向に着磁後に、コイルを巻き線し、コアロスを測定した。その結果も表１１に並べて示す。
【０１１４】
【表１１】

【０１１５】
表１１より界面活性剤を添加したものは良好なコアロス特性を示している。これは、界面活性剤を添加することにより、１次粒子の凝集を防止し、渦電流損を抑制したためである。本実施の形態ではリン酸塩を添加した結果を示したがこれ以外の界面活性剤を添加しても同様に、コアロス特性が良好である結果が得られた。
【０１１６】
（第１１の実施の形態）
Ｓｍ_２Ｃｏ_１７磁石粉末とポリイミド樹脂とをラボプラストミルで熱混練した後、熱プレス機で無磁場中でプレス成形する事により厚さ０．５ｍｍの薄板磁石を作製した。ここでポリイミド樹脂の樹脂量を調節する事により、比抵抗が各々０．０５、０．１、０．２、０．５、１．０Ω・ｃｍの薄板磁石を作製した。その後、第６の実施の形態と同様に、図１及び図２のＥ型フェライトコア４５の中央磁脚と同一断面形状に加工した。次にこのＭｎＺｎ系フェライト材で作製された磁路長７．５ｃｍ、実効断面積０．７４ｃｍのＥＥコア４５の中央磁脚の磁気ギャップに上記作製した薄板磁石３１を挿入配置し、電磁石で磁路方向に着磁後、コイル３５を巻き線し、岩崎通信機製のＳＹ−８２３２交流ＢＨトレーサーで、３００ＫＨｚ、０．１Ｔにおけるコアロス特性を室温で測定した。ここで測定に使用したフェライトコアは同一のものであり、磁石だけを比抵抗の異なるものと交換して、コアロスを測定したその結果を表１２に示す。
【０１１７】
【表１２】

【０１１８】
表１２より比抵抗０．１Ω・ｃｍ以上の磁気コアでは良好なコアロス特性を示していることがわかる。これは、薄板磁石の比抵抗をあげることにより渦電流損失を抑制できるためである。
【０１１９】
（第１２の実施の形態）
各種磁石粉末と各種樹脂とを各々表１３に示す組成で、以下の記載した方法で混練、成形、加工して厚さ０．５ｍｍの試料を作製した。ここでＳｍ_２Ｃｏ_１７系紛末とフェライト紛末は焼結体の粉砕粉末であり、Ｓｍ_２Ｆｅ_１７Ｎ紛末は還元拡散法で作製したＳｍ_２Ｆｅ_１７紛末を窒化処理した紛末であり、各粉末は平均粒径で約５μｍであった。芳香族系ポリアミド樹脂（６Ｔナイロン）とポリプロピレン樹脂はラボプラストミルを用いてＡｒ中３００℃（ポリアミド）、２５０℃（ポリプロピレン）で熱混練後、熱プレス機で成形し試料を作製した。可溶性ポリイミド樹脂は溶剤としてγ−ブチロラクトンを加えて遠心脱泡機で５分間攪拌してペーストを作製後、ドクターブレード法により出来あがりが５００μｍになるようにグリーンシートを作製し、乾燥後、熱プレスによって試料を作製した。エポキシ樹脂はビーカーで攪拌混合後金型成形し適当なキュア条件により試料を作製した。これら試料の比抵抗は全て０．１Ωｃｍ以上であった。
【０１２０】
この薄板磁石を以下に説明するフェライトコアの中芯断面形状に切断した。コアは一般的なＭｎＺｎ系フェライト材で作製された磁路長５．９ｃｍ、実効断面積０．７４ｃｍのＥＥコアであり中芯には０．５ｍｍのギャップ加工をした。そのギャップ部に上記作製した薄板磁石を挿入し、図１及び図２に示すように配置した（３１が薄板磁石、３３がフェライトコア、３５は巻き線部）。
【０１２１】
次にパルス着磁機で磁路方向に着磁後、Ｈｅｗｌｅｔ Ｐａｃｋａｒｄ製ＨＰ−４２８４Ａ ＬＣＲメーターで直流重畳特性を交流磁場周波数１００ＫＨｚ、直流重畳磁場３５ Ｏｅの実効透磁率を測定した。
【０１２２】
次にこれらコアを２７０℃のリフロー炉で３０分間保持した後、再び直流重畳特性を全く同じ条件で測定した。
【０１２３】
比較例として、ギャップに磁石を挿入しないものについても同様に測定し、これはリフロー前後で特性の変化はなく、実効透磁率μｅは７０であった。
【０１２４】
これらの結果を表１３に、また結果の１例として図７に試料▲２▼と▲４▼と比較例との直流重畳特性を示す。また直流バイアス磁界の向きは、挿入時に着磁した磁石の磁化の向きとは逆になるように重畳電流を印可するのはもちろんのことである。
【０１２５】
なおポリプロピレン樹脂の薄板磁石を挿入したコアは、磁石が著しく変形したため測定出来なかった。
【０１２６】
保磁力が４ＫＯｅしかないＢａフェライトの薄板磁石を挿入したコアではリフロー後、直流重畳特性が大きく劣化することがわかる。またＳｍ_２Ｆｅ_１７Ｎの薄板磁石を挿入したコアでもリフロー後、直流重畳特性が大きく劣化することがわかる。逆に、保磁力が１０ＫＯｅ以上でＴｃが７７０℃と高いＳｍ_２Ｃｏ_１７の薄板磁石を挿入したコアは、特性の劣化が認められず、非常に安定した特性を示すことが分かる。
【０１２７】
これらの結果よりＢａフェライト薄板磁石は保磁力が小さいために、薄板磁石に印可される逆向きの磁界によって減磁、または磁化の反転が起こり、直流重畳特性が劣化したものと推測でき、またＳｍＦｅＮ磁石は保磁力が高いもののＴｃが４７０℃と低いために熱減磁が生じ、それに逆向きの磁界による減磁の相乗効果により特性が劣化したと推測される。従って、コアに挿入する薄板磁石は保磁力が１０ＫＯｅ以上でＴｃが５００℃以上の薄板磁石において優れた直流重畳特性を示すことが分かった。
【０１２８】
また、本実施の形態では示さなかったが、本実施の形態以外の組み合わせでも、請求の範囲で示した樹脂で作製した薄板磁石においても同様の効果が得られることを確認した。
【０１２９】
【表１３】

【０１３０】
（第１３の実施の形態）
第１２の実施の形態と全く同じＳｍ_２Ｃｏ_１７系磁石粉末（ｉＨｃ＝１５ｋＯｅ）と可溶性ポリアミドイミド樹脂（東洋紡バイロマックス）を加圧ニーダーで混練後、プラネタリーミキサーで希釈混練したものを遠心脱泡機で５分間攪拌してペーストを作製した。ペーストはドクターブレード法により乾燥後の厚みが約５００μｍになるようにグリーンシートを作製し、乾燥後、熱プレス、次に厚さ０．５ｍｍに加工し、薄板磁石試料とした。ここでポリアミドイミド樹脂の樹脂量は、比抵抗が各々０．０６、０．１、０．２、０．５、１．０Ω・ｃｍとなるように表１４のとおりに調製した。これらの薄板磁石を第５の実施の形態と全く同じコアの中芯断面形状に切断し、測定試料とした。
【０１３１】
次に、第１２の実施の形態と全く同じ０．５ｍｍのギャップ長を有するＥＥコアに上記作製した薄板磁石を挿入し、パルス着磁機で磁石を着磁した。これらのコアについて、岩崎通信機製のＳＹ−８２３２交流ＢＨトレーサーを用いて３００ＫＨｚ、０．１Ｔにおけるコアロス特性を室温で測定した。ここで測定に使用したフェライトコアは同一のものであり、比抵抗の異なる磁石だけを交換、挿入し再びパルス着磁機で着磁後コアロス特性を測定した。
【０１３２】
その結果を表１４に示す。比較例として、全く同じギャップ付のＥＥコアの、同じ測定条件でのコアロス特性は５２０（ＫＷ／ｍ^３）であった。表１４から、比抵抗０．１Ωｃｍ以上の磁気コアで良好なコアロス特性を示している。これは薄板磁石の比抵抗をあげると渦電流損失を抑制できるためと推測される。
【０１３３】
【表１４】

【０１３４】
（第１４の実施の形態）
Ｓｍ（Ｃｏ_{０．７４２}Ｆｅ_０．２０Ｃｕ_{０．０５５}Ｚｒ_{０．０２９}）_７．７組成の焼結磁石（ｉＨｃ＝１５ＫＯｅ）から、粉砕時間を変えて平均粒径の異なるものを用意し、次に径の異なるふるいを通じで最大粒径を調整した。
【０１３５】
乾燥後の体積比がＳｍ_２Ｃｏ_１７磁石粉末６０ｖｏ１％とポリイミド樹脂４０ｖｏｌ％となるように、Ｓｍ _２ Ｃｏ _１７ 磁石粉末と新日本理化製リカコート（ポリイミド樹脂）に溶剤としてγ−ブチロラクトンを加えて円心脱泡機で５分攪拌してペーストを作製した。溶剤の配合比は、Ｓｍ _２ Ｃｏ_１７磁石粉末と新日本理化製リカコートを合わせて７０重量部に対してγ−ブチロラクトンを１０重量部とした。作製したペーストをドククーブレード法により５００μｍのグリーンシートを作製し乾燥、熱プレスを行った。これをフェライトコアの中芯形状に切断後、パルス着磁装置を使用して４Ｔで着磁を行い、薄板磁石を作製した。これらの薄板磁石のフラックスをＴＯＥＩ ＴＤＦ−５ Ｄｉｇｉｔａｌ Ｆｌｕｘ ｍｅｔｅｒ で測定した結果を表１５に示す。さらに第１２の実施の形態と同様にフェライトコアにはさんで直流重畳特性を測定し、次にバイアス量を測定した。バイアス量は透磁率と重畳磁界の大きさの積で求めた。
【０１３６】
【表１５】

【０１３７】
平均粒径が２．１μｍの試料▲１▼はフラックスが低下しており、バイアス量が小さい。これは作製工程中で磁石粉末の酸化が進行しているためと考えられる。また平均粒径が大きい試料▲４▼は、粉末充填率が低いためフラックスが低く、また磁石の表面粗さが粗いため、コアとの密着性が悪くパーミアンス係数が低下するため、バイアス量が低下していると考えられる。また、粒径が小さいものでも、プレス圧が充分でなく表面粗さの大きい試料▲５▼は、粉末の充填率が低いためフラックスが低下しており、バイアス量が小さい。また粗大粒が混ざっている試料▲６▼は表面粗さが粗いため、バイアス量が低下していると考えられる。
【０１３８】
これらの結果より、磁性粉の平均粒径が２５μｍ以上で、かつ最大粒径が５０μｍであり、中心線平均粗さが１０μｍ以下の薄板磁石を挿入したとき、薄板磁石そ挿入したときに、優れた直流重畳特性を示すことがわかった。
【０１３９】
（第１５の実施の形態）
Ｓｍ_２Ｃｏ_１７系でＺｒ量が０．０１ａｔ％で組成がＳｍ（Ｃｏ_０．７８Ｆｅ_０．１１Ｃｕ_０．１０Ｚｒ_０．０１）_８．２の俗に第２世代Ｓｍ_２Ｃｏ_１７磁石と呼ばれる組成のインゴットを粗粉砕後に熱処理した磁石紛末と、Ｚｒ量が０．０２９ａｔ％で組成がＳｍ（Ｃｏ_{０．０７４２}Ｆｅ_０．２０Ｃｕ_{０．０５５}Ｚｒ_{０．０２９}）_８．２の俗に第３世代Ｓｍ２Ｃｏ１７磁石と呼ばれる組成のインゴツドを粗粉砕後に熱処理した磁石粉末を用いた。上記第２世代Ｓｍ_２Ｃｏ_１７磁石粉末は８００℃で１．５Ｈｒの時効熱処理を行い、第３世代Ｓｍ_２Ｃｏ_１７磁石は８００℃で１０Ｈｒの時効熱処理を行った。これによってＶＳＭで測定された磁石粉末の保磁力は、第２世代か８ＫＯｅで第３世代が２０ＫＯｅであった。これらの粗粉砕粉末を、有機溶媒中でボールミルにより平均粒径５．２μｍに微粉砕し、さらに目開き４５μｍの篩を通し、磁石粉末を得た。次にこれら作製した磁石粉末にそれぞれバインダーとしてエポキシ樹脂を３５ｖｏ１％混合し、第１２の実施の形態と全く同しＥＥコアの中芯形状と厚み０．５ｍｍのボンド磁石を金型成形により作製した。ここで磁石特注はφ１０×ｔ１０のテストピースを別途作製し、直流ＢＨトレーサーで測定した。
【０１４０】
保磁力は粗粉砕粉末とほほ同様の値であった。次にこれら磁石を第１２の実施の形態と全く同じＥＥコアに挿入後、パルス着磁、巻き線後、ＬＣＲメータで４０Ｏｅ直流重畳時の１００ＫＨｚにおける実効透磁率を測定した。次に、これらコアをリフロー炉の条件である２７０℃の恒温槽で１Ｈｒ保持した後、上記と同様に直流重畳特性を測定した。その結果も表１６に示す。
【０１４１】
【表１６】

【０１４２】
表１６より保磁力の高い第３世代Ｓｍ_２Ｃｏ_１７磁石粉末を使用した場合、リフロー後も良好な直流重畳特性が得られることがわかった。なお、Ｓｍと遷移金属の比で保磁力のピークを有することが知られているが、この最適値の組成比は合金に含有される酸素量によって変動することが知られており、焼結体は７．０〜８．０でインゴットは８．０〜８．５の間で変動することを確認している。以上より組成が第３世代であるＳｍ（Ｃｏ_ｂａｌ．Ｆｅ_{０．１５−０．２５}Ｃｕ_{０．０５−０．０６}Ｚｒ_{０．０２−０．０３}）_{７．０−８．５}でリフロー条件でも直流重畳特性が良好であることがわかった。
【０１４３】
（第１６の実施の形態）
第１４の実施の形態の試料▲３▼で作製した、組成がＳｍ（Ｃｏ_{０．７４２}Ｆｅ_０．２０Ｃｕ_{０．０５５}Ｚｒ_{０．０２９}）_７．７で粒径が平均で５μｍ、最大粒径で４５μｍの磁石紛末を用いた。その磁石粉末の表面にＺｎ、無機ガラス（ＺｎＯ−Ｂ_２Ｏ_３−ＰｂＯ）軟化点４００℃、Ｚｎ後更に無機ガラス（ＺｎＯ‐Ｂ_２Ｏ_３−ＰｂＯ）を被覆した薄板磁石を第１３の実施の形態の試料▲２▼と全く同様の方法で作製し、それを挿入したＭｎ‐Ｚｎ系フェライトコアの直流重畳特性は第１２の実施の形態と全く同様に測定後バイアス量を求め、コアロス特性は第１３の実施の形態と全く同様の方法で測定し、比較を行った結果を表１７に示す。
【０１４４】
ここでＺｎは磁石粉末と混合後、５００℃，Ａｒ雰囲気下で２時間熱処理を施した。ＺｎＯ−Ｂ_２Ｏ_３−ＰｂＯは熱処理温度が４５０℃以外は全く同じ方法で熱処理した。一方、複合層を形成するためには始めにＺｎと磁石粉末とを混合し５００℃で熱処理し、ここで一旦炉から取り出してこの粉末とＺｎＯ−Ｂ_２Ｏ_３−ＰｂＯ粉末を混合後、４５０℃で熱処理する。これら紛末は総体積の４５ｖｏｌ％に当たる量のバインター（エポキシ樹脂）を混合した後、無磁場中で金型成形を行った。成形体は第１２の実施の形態と全く同じフェライトコアの中芯断面形状でかつ高さ０．５ｍｍでありコアに挿入後約１０Ｔのパルス磁場で着磁して、第１２の実施の形態と同じ方法で直流重畳特性と第１３の実施の形態と同じ方法でコアロス特性とを測定した。次にこれらコアを２７０℃の恒温糟で３０分間保持した後、同様に直流重畳特性、コアロス特性を測定した。比較例として被覆していない粉末でも全く同じ方法で成形体を作製後、特性を測定した結果も表１７に示す。
【０１４５】
未被覆のものは熱処理により大きく直流重畳特性、コアロス特性が劣化するが、Ｚｎ、無機ガラス、及びその複合体を被覆したものは未被覆のものに比へ、熱処理における劣化率は非常に小さいことが分かる。これは被覆により磁石粉末の酸化が抑制されたためと推測できる。
【０１４６】
また被覆材を１０ｖｏ１％以上混合したものについては実効透磁挙が低く、磁石によるバイアス磁界の大きさが他のものに比へ非常に小さくなっていることか分かる。これは被覆材の量が増大したために、磁石粉末の割合が減少したため、もしくは磁石粉末と被覆材が反応し磁化の大きさが減少したためと考えられる。従って被覆する量は０．１〜１０ｗｔ％の範囲で非常に優れた特性を示すことが分かった。
【０１４７】
【表１７】

【０１４８】
（第１７の実施の形態）
第１４の実施の形態の試料▲３▼のＳｍ_２Ｃｏ_１７磁石劾末を用い、バインダーとしてエポキシ樹脂を５０ｖｏ１％混合した後、２Ｔの磁場中で中足上下方向に金型成形し異方性の磁石を作製した。また、比較例として無磁場中で金型成形したものも同様に作製した。次にこれらの各ボンド磁石を第１２の実施の形態と同様にＭｎＺｎ系フェライト材に挿入し、パルス着磁、巻き線を施し、ＬＣＲメーターで直流重畳特性を測定し、コア定数と巻線数から透磁率を計算した。その結果を表１８に示す。
【０１４９】
また、測定が終わった試料をリフローの条件である２７０℃の恒温糟で１Ｈｒ保持し常温まで冷却し上記と同様にＬＣＲメーターて直流重畳特注を測定した。その結果も表１８に示す。
【０１５０】
表１８よりリフロー前後とも無磁場磁石に比べ良好な結果が得られることがわかった。
【０１５１】
【表１８】

【０１５２】
（第１８の実施の形態）
第１４の実施の形態の試料（３）のＳｍ_２Ｃｏ_１７磁石粉末を用い、バインダーとしてエポキシ樹脂を５０ｖｏ１％混合した後、無磁場中で金型成形し０．５ｍｍ厚の磁石を作製したところまでは第２０の実施の形態と全く同じである。次に第１２の実施の形態と同様にＭｎＺｎ系フェライト材に挿入し着磁を行った。このときの磁場を１Ｔ、２Ｔ、２．５Ｔ、３Ｔ、５Ｔ、１０Ｔで着磁を行った。１Ｔ、２Ｔ、２５Ｔは、電磁石で着磁し、３Ｔ、５Ｔ、１０Ｔはパルス着磁機で着磁した。その後、ＬＣＲメーターで直流重畳物性を測定し、コア定数と巻線数から透磁率を計算した。その結果から第１７の実施の形態で求めた方法でバイアス量を求めその結果を図９に示す。
【０１５３】
図９より２．５Ｔ以上でないと良好な重畳特性が得られないことがわかった。
【０１５４】
（第１９の実施の形態）
図１０及び図１１を参照すると、本発明の第１９の実施の形態による薄板磁石を適用したインダクタンス部品において、使用するコア３９は、ＭｎＺｎ系フェライト材で作製され磁路長２．４６、実効断面積０．３９４ｃｍ_２のＥＥ型磁芯を形成する。図１１のように、Ｅ型コア３９に、モールドコイル（樹脂封止された巻線（巻回数４ターン））４１を組み込んだ後、さらにＥ型コア３９の中脚断面積と同形状に加工された、厚み０．１６ｍｍの薄板磁石４３を、コアキャップ部に配置して、もう片側のコア３９により挾みこんでインダクタンス部品として機能するものである。
【０１５５】
薄型磁石４３の着磁方向は、モールドコイルが作る磁界と逆向きに着磁されているものとする。
【０１５６】
薄型磁石を適用した場合の直流重畳インダクタンス特性と、比較として薄型磁石を適用しない場合の直流重畳インダクタンス特性を測定し、結果を図１２の４５（前者）と４７（後者）に示す。
【０１５７】
またリフロー炉（ピーク温度２７０℃）に通した後、上記同様直流重畳インダクタンス特性を測定し、その結果、リフロー前の結果と同様である事を確認した。
【０１５８】
（第２０の実施の形態）
図１３及び図１４を参照すると、本発明の第２０の実施の形態において、使用するコアは第１９の実施の形態と同様、ＭｎＺｎ系フェライト材で作製され磁路長２．４６ｃｍ、実効断面積０．３９４ｃｍの磁芯を形成するが、ＥＩ型磁芯を形成してインダクタンス部品として機能する。組立工程も第１９の実施の形態と同様であるが、片側のフェライトコア５３の形状は、Ｉ型である。
【０１５９】
薄型磁石を適用した直流重畳インダクタンス特性、及びリフロー炉に通した後の直流重畳インダクタンス特性は、第１９の実施の形態と変化はない。
【０１６０】
（第２１の実施の形態）
図１５及び図１６を参照すると、本発明の第２１の実施の形態による薄板磁石を適用したインダクタンス部品においては、使用するコア６５はＭｎＺｎ系フェライト材で作製され磁路長０．０２ｍ、実効断面積５×１０^−６ｃｍのＵＵ型磁芯を形成する。図１６のように、ボビン６３にコイル６７を巻回し、一対のＵ型コア６５を組み込む際、Ｕ型コア６５の断面積（接合部）と同形状に加工された、厚み０２ｍｍの薄板磁石６９を、コアギャップ部に配置する。これにより、透磁率４×１０^−３Ｈ／ｍのインダクタンス部品として機能するものである。
【０１６１】
薄型磁石６９の着磁方向は、コイルが作る磁界と逆向きに着磁されているものとする。
【０１６２】
薄型磁石を適用した場合の直流重畳インダクタンス特性と、比較として薄型磁石を適用しない場合の直流重畳インダクタンス特性を測定し、結果を図１７の７１（前者）と７３（後者）に示す。
【０１６３】
上記直流重畳インダクタンス特性の結果は、一般に磁芯を形成するコアの使用磁束密度（△Ｂ）の拡大を示していることと等価であり（図１８により補足，図１８の７５は従来のインダクタンス部品に対するコアの使用領域を示し、図１８の７７は本発明による薄板磁石を連用したインダクタンス部品のコアの使用領域を示す。これらの図は、前記直流重畳インダクタンス特性の結果７１と７７と７３と７５の各々対応する）インダクタンス部品の一般的な理論式は次の数１式により表わされる。
【０１６４】
【数１】

【０１６５】
この数１式より、前記使用磁束密度（△Ｂ）拡大の効果は、巻回数Ｎと磁芯の実効断面積Ａｅの逆数に比例し、前者はインダクタンス部品の巻回数を減らすことで銅損失低減の効果とインダクタンス部品の小型化をもたらし、後者は、磁芯を形成するコアの小型化に寄与して、前記巻回数低減による小型化と併せて、インダクタンス部品の小型化に大きく寄与することか明らかである。トランスにおいては一次及び二次コイル巻回数を低減できるため、その効果は絶大である。
【０１６６】
さらに出力電力に関する式を数２式に示すが、この式から使用磁束密度（△Ｂ）拡大効果は、出力電力拡大の効果にも作用していることが言える。
【０１６７】
【数２】

【０１６８】
また、インダクタンス部品の信頼性に関し、リフロー炉（ピーク温度２７０℃）に通した後、上記同様直流重畳インダクタンス特性を測定し、その結果、リフロー前の結果と同様である事を確認した。
【０１６９】
（第２２の実施の形態）
図１９及び図２０を参照すると、本発明の第２２の実施の形態による薄板磁石を適用したインダクタンス部品では、使用するコアは第２１の実施の形態と同様、ＭｎＺｎ系フェライト材で作製され磁路長０．０２ｍ、実効断面積５×１０^−６ｍ^２の磁芯を形成するか、ＵＩ型磁芯を形成してインダクタンス部品として機能する。図２０のように、ボビン８５にコイル８３を巻回し、Ｉ型コア８７をボビン８５に組み込んだ後、Ｕ型コア８９の断面積（接合部）と同形状に加工された、厚み０．１ｍｍの薄板磁石９１を、コイルを巻回したボビンの両翼部（Ｉ型コア８７がボビンからはみ出す部分）に各１枚（両翼で２枚）づつ配置して、Ｕ型コア８９を組み込んで完成する。
【０１７０】
薄型磁石を適用した直流重畳インダクタンス特性、及びリフロー炉投入後の直流重畳インダクタンス特性は、第２１の実施の形態と変化はない。
【０１７１】
（第２３の実施の形態）
図２１及び図２２を参照すると、本発明の第２３の実施の形態による薄板磁石を適用したインダクタンス部品においては、使用する４本のＩ型コア９５は珪素鋼で作製され、磁路長０．２ｍ、実効断面積１×１０^−４ｍ^２の口の字型磁芯を形成する。図２１のように、絶縁紙９７を備えた２つのコイル９９に、各１本ずつＩ型コア９５を挿入し、口の字の磁路を形成するように、もう２本のＩ型コア９５を組む。その接合部に本発明による薄板磁石１２３を配置して、透磁率２×１０^−２Ｈ／ｍの口の字型の磁路を形成してインダクタンス部品として機能する。
【０１７２】
薄型磁石１０１の着磁方向は、コイルが作る磁界と逆向きに着磁されているものとする。
【０１７３】
薄型磁石を適用した場合の直流重畳インダクタンス特性と、比較として薄型磁石を適用しない場合の直流重畳インダクタンス特性を測定し、結果を図２３の１１０３（前者）と１０５（後者）に示す。
【０１７４】
上記直流重畳インダクタンス特性の結果は、一般に磁芯を形成するコアの使用磁束密度（△Ｂ）の拡大を示していることと等価であり（図２４により補足，図２４の１０７は従来のインダクタンス部品に対するコアの使用領域を示し、図２４の１０９は本発明による薄板磁石を適用したインダクタンス部品のコアの使用領域を示す。これらの図は、前記直流重畳インダクタンス特性の結果１０３と１０５、１０９と１０７の各々対応する）、インダクタンス部品の一般的な理論式は次の数３式により表わされる。
【０１７５】
【数３】

【０１７６】
この数３式より、前記使用磁束密度（△Ｂ）拡大の効果は、巻回数Ｎと磁芯の実効断面積Ａｅの逆数に比例し、前者はインダクタンス部品の巻回数を減らすことで銅損失低減の効果とインダクタンス部品の小型化をもたらし、後者は、磁芯を形成するコアの小型化に寄与して、前記巻回数低減による小型化と併せて、インダクタンス部品の小型化に大きく寄与することか明らかである。トランスにおいては一次及び二次コイル巻回数を低減できるため、その効果は絶大である。
【０１７７】
さらに出力電力に関する式を数４式に示すが、この式から使用磁束密度（△Ｂ）拡大効果は、出力電力拡大の効果にも作用していることが言える。
【０１７８】
【数４】

【０１７９】
また、インダクタンス部品の信頼性に関し、リフロー炉（ピーク温度２７０℃）に通した後、上記同様直流重畳インダクタンス特性を測定し、その結果、リフロー前の結果と同様である事を確認した。
【０１８０】
（第２４の実施の形態）
図２５及び図２６を参照すると、本発明の第２４の実施の形態による薄板磁石を適用したインダクタンス部品においては、凹状のくぼみを有する口の字型コア１１３とＩ型コア１１５、コイル１１７が巻線されたボビン１１９及び薄板磁石１２１で構成される。図２６のように、薄板磁石１２１は、口の字型コア１１３の凹状くぼみ部、すなわち口の字型コア１１３とＩ型コア１１５の接合部に配置される。
【０１８１】
ここで使用の口の字型コア１１３及びＩ型コア１１５は、ＭｎＺｎ系フェライト材で、磁路長６．０ｃｍ、実効断面積０．１ｃｍ^２の日の字型磁芯を形成する。
【０１８２】
また、薄板磁石１２１は、厚み０．２５ｍｍ、断面積０．１ｃｍ^２であって、コイルが作る磁界と逆向きに着磁されているものとする。
【０１８３】
コイル１１７は１８ターン巻回されており、本インダクタンス部品の直流重畳インダクタンス特性と、比較として薄型磁石を適用しない場合の直流重畳インダクタンス特性を測定し、結果を図２７の１２３（前者）と１２５（後者）に示す。
【０１８４】
またリフロー炉（ピーク温度２７０℃）に通した後、上記同様直流重畳インダクタンス特性を測定し、その結果、リフロー前の結果と同様である事を確認した。
【０１８５】
（第２５の実施の形態）
図２８及び図２９を参照すると、本発明の第２５の実施の形態による薄板磁石を適用したインダクタンス部品は、凸状コア１３５にコイル１３１が巻線され凸状コア１３５の凸部上面に、この凸部上面と同形状（０．０７ｍｍ）で、厚み１２０μｍの薄板磁石１３３を配置して、円筒状のキャップコア１２９を被せて構成されているものである。
【０１８６】
ここで使用の凸状コア１３５及び円筒状のキャップコア１２９は、ＮｉＺｎ系フェライト材で、磁路長１．８５ｃｍ、実効断面積０．０７ｃｍ^２の磁芯を形成する。
【０１８７】
また薄板磁石１３３は、コイルが作る磁界と逆向きに着磁されているものとする。
【０１８８】
コイル１３１は１５ターン巻回されており、本インダクタンス部品の直流重畳インダクタンス特性と、比較として薄型磁石を適用しない場合の直流重畳インダクタンス特性を測定し、結果を図３０の１３９（前者）と１４１（後者）に示す。
【０１８９】
またリフロー炉（ピーク温度２７０℃）に通した後、上記同様直流重畳インダクタンス特性を測定し、その結果、リフロー前の結果と同様である事を確認した。
【０１９０】
以上説明したように、本発明の３発明によれば、５００μｍ以下の薄板磁石が得られ、この薄型磁石を磁気バイアス磁石として使用することにより、小型で、高周波における磁気コアの直流重畳特性が向上した且つリフロー温度でも特性の劣化のない磁気コア及び、この磁気コアを用いて、リフローにて特性の劣化の恐れなく表面実装を可能としたインダクタンス素子を提供することができる。
【０１９１】
【発明の効果】
以上に説明したように、本発明においては、磁路の少なくとも１箇所以上にギャップを有する磁気コアであって、その磁気ギャップに挿入配置する磁気バイアス用磁石を、固有保磁力ｉＨｃが１０ＫＯｅ以上、キュリー点Ｔｃが５００℃以上、粉末粒径が２．５〜５０μｍの希土類磁石粉末を用いたボンド磁石とし、その磁石粉末表面を無機ガラスで被覆し、その粉末と少なくとも体積比で３０％以上の樹脂からなる比抵抗が１Ωｃｍ以上のボンド磁石を用いることによって、直流重畳特性、コアロス特性、耐酸化性に優れた磁気コアを提供することができる。
【０１９２】
また、本発明においては、磁路の少なくとも１箇所以上にギャップを有する磁気コアであって、その磁気ギャップに挿入配置する磁気バイアス用磁石を、固有保磁力ｉＨｃが５ＫＯｅ以上、キュリー点Ｔｃが３００℃以上、粉末粒径が２．０〜５０μｍの希土類磁石粉末を用いたボンド磁石とし、その磁石粉末表面を無機ガラスで被覆し、その粉末と少なくとも体積比で２０％以上の樹脂からなる比抵抗が１Ωｃｍ以上のボンド磁石を用いることによって、直流重畳特性、コアロス特性、耐酸化性に優れた磁気コアを提供することができる。
【０１９３】
また、本発明においては、５００μｍ以下の薄板磁石が得られ、この薄型磁石を磁気バイアス磁石として使用することにより、小型で、高周波における磁気コアの直流重畳特性が向上した且つリフロー温度でも特性の劣化のない磁気コア及び、この磁気コアを用いて、リフローにて特性の劣化の恐れなく表面実装を可能としたインダクタンス部品を提供することができる。
【図面の簡単な説明】
【図１】図１は本発明の１実施の形態によるチョークコイルのコイル巻回前の一例を示す斜視図である。
【図２】図１のチョークコイルの側面図である。
【図３】本発明の第６の実施の形態におけるＳｍ_２Ｃｏ_１７磁石とポリイミド樹脂からなる薄板磁石の直流重畳特性の測定データを示す図である。
【図４】本発明の第６の実施の形態におけるＳｍ_２Ｃｏ_１７磁石とエポキシ樹脂からなる薄板磁石の直流重畳特性の測定データを示す図である。
【図５】本発明の第６の実施の形態におけるＳｍ_２Ｃｏ_１７Ｎ磁石とポリイミド樹脂からなる薄板磁石の直流重畳特性の測定データを示す図である。
【図６】本発明の第６の実施の形態におけるＢａフェライト磁石とポリイミド樹脂からなる薄板磁石の直流重畳特性の測定データを示す図である。
【図７】本発明の第６の実施の形態におけるＳｍ_２Ｃｏ_１７磁石とポリプロピレン樹脂からなる薄板磁石の直流重畳特性の測定データを示す図である。
【図８】本発明の第１２の実施の形態における試料２および４からなる薄板磁石を用いた場合と、薄板磁石を用いない場合について、リフロー前後における直流重畳特性の測定データを示す図である。
【図９】本発明の第１８の実施の形態におけるＳｍ２Ｃｏ１７磁石−エポキシ樹脂薄板磁石の着磁磁界と直流重畳特性を示す図である。
【図１０】本発明の第１９の実施の形態による薄板磁石を適用したインダクタンス部品を示す外観斜視図である。
【図１１】図１０のインダクタンス部品の分解組立斜視図である。
【図１２】本発明の第１９の実施の形態の薄型磁石を適用した場合の直流重畳インダクタンス特性と、比較として薄型磁石を適用しない場合の直流重畳インダクタンス特性の測定結果を示す図である。
【図１３】本発明の第２０の実施の形態による薄板磁石を適用したインダクタンス部品を示す外観斜視図である。
【図１４】図１３のインダクタンス部品の分解組立斜視図である。
【図１５】本発明の第２１の実施の形態による薄板磁石を適用したインダクタンス部品を示す外観斜視図である。
【図１６】図１５のインダクタンス部品の分解組立斜視図である。
【図１７】本発明の第２１の実施の形態の薄型磁石を適用した場合の直流重畳インダクタンス特性と、比較として薄型磁石を適用しない場合の直流重畳インダクタンス特性の測定結果を示す図である。
【図１８】（ａ）は従来のインダクタンス部品のコア使用領域を示す図である。
（ｂ）は本発明の第２２の実施の形態による薄型磁石を適用した場合のインダクタンス部品のコア使用領域を示す図である。
【図１９】本発明の第２２の実施の形態による薄板磁石を適用したインダクタンス部品を示す外観斜視図である。
【図２０】図１９のインダクタンス部品の分解組立斜視図である。
【図２１】本発明の第２３の実施の形態による薄板磁石を適用したインダクタンス部品を示す外観斜視図である。
【図２２】図２１のインダクタンス部品の分解組立斜視図である。
【図２３】図２３は薄型磁石を適用した場合の直流重畳インダクタンス特性と、比較として薄型磁石を適用しない場合の直流重畳インダクタンス特性の測定結果を示す図である。
【図２４】（ａ）は従来のインダクタンス部品に対するコアの使用領域を示す図である。
（ｂ）は本発明の第２３の実施の形態による薄板磁石を適用したインダクタンス部品のコアの使用領域を示す図である。
【図２５】本発明の第２４の実施の形態による薄板磁石を適用したインダクタンス部品を示す外観斜視図である。
【図２６】図２５のインダクタンス部品の磁路を形成するコアと薄板磁石の構成斜視図である。
【図２７】本発明の薄板磁石を適用した場合のインダクタンス特性と、比較として薄型磁石を適用しない場合の直流重畳インダクタンス特性を測定結果を示す図である。
【図２８】本発明の第２５の実施の形態による薄板磁石を適用したインダクタンス部品の断面図を示す図である。
【図２９】図２８のインダクタンス部品の磁路を形成するコアと薄板磁石の構成斜視図である。
【図３０】図３０は本発明の第２５の実施の形態によるインダクタンス部品の直流重畳インダクタンス特性と、比較として薄型磁石を適用しない場合の直流重畳インダクタンス特性の測定結果を示す図である。
【符号の説明】
３１ 磁石
３３ コア
３５ コイル
３７ インダクタンス部品
３９ コア
４１ コイル
４３ 磁石
５１ インダクタンス部品
５３ コア
５５ コア
５９ 磁石
６１ インダクタンス部品
６３ ボビン
６５ コア
６７ 巻線（コイル）
６９ 磁石
８１ インダクタンス部品
８３ コイル
８５ ボビン
８７ コア
８９ コア
９１ 磁石
９３ インダクタンス部品
９５ コア
９７ 絶縁紙
１０１ 磁石
１１１ インダクタンス部品
１１３ コア
１１５ コア
１１７ コイル
１１９ ボビン
１２１ 磁石
１２７ インダクタンス部品
１２９ コア
１３１ コイル
１３３ 磁石
１３５ コア
１３７ 端子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic core of an inductance component such as a choke coil or a transformer (hereinafter also simply referred to as “core”), and more particularly to a magnetic core including a permanent magnet for magnetic bias.
[0002]
[Prior art]
Conventionally, for example, in a choke coil and a transformer used for a switching power supply or the like, an alternating current is usually applied by being superimposed on a direct current. Therefore, magnetic cores used for these choke coils and transformers are required to have good permeability characteristics (this characteristic is referred to as “DC superposition characteristics”) that does not magnetically saturate with respect to this DC superposition.
[0003]
Ferrite magnetic cores and dust magnetic cores are used as high-frequency magnetic cores, but ferrite magnetic cores have high initial permeability and low saturation magnetic flux density, and powder magnetic cores have low initial magnetic permeability and saturation magnetic flux density. There is a feature derived from the material properties of high. Therefore, the dust core is often used in a toroidal shape. On the other hand, in the case of a ferrite magnetic core, for example, a magnetic air gap (magnetic gap) is formed in the middle leg of an E-type core to avoid magnetic saturation due to DC superposition.
[0004]
However, due to the demand for downsizing of electronic components in response to the downsizing of electronic devices in recent years, the magnetic gap of the magnetic core has to be reduced, and a magnetic core with higher permeability against DC superposition is strongly demanded. ing.
[0005]
In order to meet this requirement, it is generally essential to select a magnetic core having a high saturation magnetization, that is, a magnetic core that is not magnetically saturated with a high magnetic field. However, the saturation magnetization is inevitably determined by the composition of the material and cannot be made infinitely high.
[0006]
As a solution to this problem, it has long been proposed to dispose a permanent magnet in a magnetic gap provided in a magnetic path of a magnetic core and cancel a DC magnetic field due to DC superposition, that is, to give a magnetic bias to the magnetic core.
[0007]
This magnetic bias method using a permanent magnet is an excellent method for improving the DC superposition characteristics. On the other hand, if a sintered metal magnet is used, the core loss of the magnetic core is significantly increased. If a ferrite magnet is used, The superimposition characteristics were not stable, so it was not very practical.
[0008]
As a means for solving these problems, for example, Japanese Patent Laid-Open No. 50-133453 uses a bonded magnet obtained by mixing and molding a rare earth magnet powder having a high coercive force and a binder as a permanent magnet for magnetic bias. And that the temperature rise of the core has been improved.
[0009]
[Problems to be solved by the invention]
However, in recent years, demands for improving the power conversion efficiency for power supplies have become increasingly severe, and the magnetic cores for choke coils and transformers are at a level that cannot be determined by simply measuring the core temperature. Therefore, it is indispensable to judge the measurement result by the core loss measuring device, and as a result of actual study by the present inventors, it is clear that the core loss characteristic deteriorates at the resistivity value shown in Japanese Patent Laid-Open No. 50-133453. Became.
[0010]
In addition, with the recent miniaturization of electronic equipment, there is an increasing demand for miniaturization of inductance components, and therefore, there is also a demand for a thin magnetic bias magnet.
[0011]
In recent years, a surface mount type coil has been desired, but for surface mounting, the coil is subjected to reflow soldering. It is desired that the characteristics of the magnetic core of the coil do not deteriorate under this reflow condition. In addition, an oxidation-resistant rare earth magnet is essential.
[0012]
Accordingly, one technical problem of the present invention is to provide a magnetic core having a permanent magnet disposed in the vicinity of the gap in order to supply a magnetic bias from both ends of the gap to a magnetic core having a gap in at least one part of the magnetic path. In consideration of the above, the magnetic core having a bias magnet has an excellent DC superimposition characteristic, core loss characteristic, and oxidation resistance, and provides a magnetic core that does not deteriorate even under reflow conditions easily and inexpensively. There is to do.
[0013]
  Another technical problem of the present invention is to provide a magnetic core having a gap in at least one magnetic path of a small inductance component.thisIn order to supply a magnetic bias from both ends of the gap, a magnetic core provided with a magnet that is particularly suitable for miniaturization of a magnetic core having a magnetic bias magnet in which a permanent magnet is arranged in the vicinity of the gap is provided. There is to do.
[0014]
Still another technical problem of the present invention is to provide an inductance component using the magnet and the magnetic core.
[0015]
[Means for Solving the Problems]
  According to the present invention, a bonded magnet in which magnet powder is dispersed in a resin,1Ω · cmThe magnetic powder having the above specific resistance is formed by coating an inorganic glass with a powder having an intrinsic coercive force of 5 KOe or more, a Curie point Tc of 300 ° C. or more, and a powder particle size of 150 μm or less.And containing 10% or less of the inorganic glass by weight.The permanent magnet characterized by this can be obtained.
[0016]
Further, according to the present invention, a magnetic core having a magnetic bias magnet disposed in the vicinity of the magnetic gap in order to supply a magnetic bias from both ends of the gap to a magnetic core having a magnetic gap in at least one part of the magnetic path. In the core, a magnetic core having a magnetic bias magnet is obtained, wherein the magnetic bias magnet is the permanent magnet.
[0017]
  Also,According to the present invention, a magnetic core having a magnetic gap having a gap length of about 50 to 10000 μm is provided at least at one location of the magnetic path, and a magnetic bias is provided in the vicinity of the magnetic gap in order to supply a magnetic bias from both ends of the magnetic gap. In the inductance component having the magnetic bias magnet and the coil winding wound around the magnetic core for at least one turn, the magnetic bias magnet has a ratio of resin and magnet powder dispersed in the resin. A bonded magnet with a resistance of 1 Ω · cm or more. The magnet powder is coated with an inorganic glass with a rare earth magnet powder having an intrinsic coercive force of 5 KOe or more, a Curie point of 300 ° C. or more, a maximum particle size of 150 μm, and an average particle size of 2 to 50 μm. The rare earth magnet powder is composed of Sm—Co magnet powder, Nd—Fe—B magnet powder, and Sm—Fe—N magnet powder. Which has been selected from the group consisting ofYes, the bonded magnet contains the inorganic glass in a weight ratio of 10% or less.An inductance component characterized by this can be obtained.According to the present invention, a magnetic core having a magnetic gap having a gap length of about 50 to 10000 μm at least at one location of the magnetic path, and a magnetic bias near the magnetic gap for supplying a magnetic bias from both ends of the magnetic gap. In an inductance component having a magnetic bias magnet disposed on the magnetic core and a coil winding wound around the magnetic core for at least one turn, the magnetic bias magnet includes a resin and a resin in the resin. A bonded magnet having a specific resistance of 1 Ω · cm or more, the magnet powder having an intrinsic coercive force of 10 KOe or more, a Curie point of 500 ° C. or more, a maximum particle size of 150 μm, and an average particle size of 2.5 ˜50 μm Sm—Co rare earth magnet powder, which is coated with inorganic glass, and the bonded magnet is made of the inorganic glass. Inductance component is obtained which is characterized in that it contains an amount ratio of 10% or less. According to the present invention, a magnetic core having a magnetic gap having a gap length of about 500 μm or less at least at one location of the magnetic path and a magnetic bias from both ends of the magnetic gap are provided in the vicinity of the magnetic gap. In an inductance component having a magnetic bias magnet arranged and a coil winding wound around the magnetic core for at least one turn, the magnetic bias magnet is dispersed in the resin and the resin. A bonded magnet having a specific resistance of 0.1 Ω · cm or more and a thickness of 500 μm or less, the magnet powder having an intrinsic coercive force of 10 KOe or more, a Curie point of 500 ° C. or more, a maximum particle size of 150 μm, The Sm—Co rare earth magnet powder having an average particle diameter of 2.5 to 50 μm and coated with an inorganic glass, the bond magnet Contains 10% or less of the inorganic glass by weight, thereby obtaining an inductance component. Furthermore, according to the present invention, a magnetic core having a magnetic gap having a gap length of about 500 μm or less at least at one location in the magnetic path and a magnetic bias from both ends of the magnetic gap are provided in the vicinity of the magnetic gap. In an inductance component having a magnetic bias magnet arranged and a coil winding wound around the magnetic core for at least one turn, the magnetic bias magnet is dispersed in the resin and the resin. A bonded magnet having a specific resistance of 0.1 Ω · cm or more and a thickness of 500 μm or less, the magnet powder having an intrinsic coercive force of 10 KOe or more, a Curie point of 500 ° C. or more, a maximum particle size of 150 μm, The Sm—Co rare earth magnet powder having an average particle size of 2.5 to 50 μm and coated with an inorganic glass, The stone contains the inorganic glass in a weight ratio of 10% or less, thereby obtaining an inductance component.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
First, one invention of the present invention will be specifically described.
[0020]
In one aspect of the present invention, in order to supply a magnetic bias from both ends of a gap to a magnetic core having a gap in at least one location of a magnetic path, a magnetic bias magnet comprising a permanent magnet in the vicinity of the gap is provided. In order to solve the above-mentioned problem in the magnetic core having, the permanent magnet is composed of a rare earth magnet powder having an intrinsic coercive force of 10 KOe or more and a Curie temperature of 500 ° C. or more and a powder average particle diameter of 2.5 to 50 μm and a resin. A magnetic core having a magnetic bias magnet in which the magnet powder is coated with inorganic glass.
[0021]
The bonded magnet as the magnetic bias magnet preferably contains the resin in a volume ratio of 30% or more and has a specific resistance of 1 Ωcm or more.
[0022]
The inorganic glass preferably has a softening point of 400 ° C. or higher and 550 ° C. or lower.
[0023]
Moreover, it is preferable that the said bond magnet contains the said inorganic glass which coat | covers the said magnet powder 10% or less by weight ratio.
[0024]
Another aspect of the present invention is an inductance component in which at least one winding of one turn or more is provided on the magnetic core having the magnetic bias magnet.
[0025]
Furthermore, the rare earth magnet powder is Sm.₂Co₁₇A magnet powder is preferred.
[0026]
Inductance components include coils, choke coils, transformers, and other components that generally require a magnetic core and windings.
[0027]
In the invention of the present invention, as a result of examining the permanent magnet inserted into the magnetic core, excellent direct current superposition characteristics are obtained when a permanent magnet having a specific resistance of 1 Ωcm or more and an intrinsic coercive force iHc of 10 KOe or more is used. In addition, the present inventors have found that a magnetic core that does not cause deterioration of core loss characteristics can be formed. This is because the magnet characteristic required to obtain an excellent DC superposition characteristic is an intrinsic coercive force rather than an energy product. Therefore, even if a permanent magnet having a low energy product is used, if the intrinsic coercive force is high, the DC characteristic is sufficiently high. This is because it has been found that superimposition characteristics can be obtained.
[0028]
A magnet having a high specific resistance and a high intrinsic coercive force is generally obtained by a rare earth bonded magnet formed by mixing rare earth magnet powder with a binder, but any composition of magnet powder having a high coercive force can be obtained. A thing is also possible. The types of rare earth magnet powders are SmCo, NdFeB, and SmFeN.
[0029]
Considering reflow conditions and oxidation resistance, a magnet having a Curie point Tc of 500 ° C. or more and an intrinsic coercive force iHc of 10 KOe or more is required.₂Co₁₇Limited to system magnets.
[0030]
As the magnetic core for choke coil and transformer, any material having soft magnetic properties is effective, but generally MnZn-based or NiZn-based ferrite, powder magnetic core, silicon steel plate, amorphous, etc. are used. . Further, the shape of the magnetic core is not particularly limited, and the present invention can be applied to magnetic cores having any shape such as a toroidal core, an EE core, and an EI core. A gap is provided in at least one of the magnetic paths of these cores, and a permanent magnet is inserted into the gap.
[0031]
There is no particular limitation on the gap length, but if the gap length is too narrow, the DC superimposition characteristics deteriorate, and if the gap length is too wide, the magnetic permeability decreases too much, so that the gap length to be inserted is determined naturally. The bias effect can be easily obtained if the thickness of the magnetic bias permanent magnet is large. However, the thinner the magnetic bias permanent magnet is, the better for miniaturization of the magnetic core. However, if it is smaller than 50 μm, a sufficient magnetic bias cannot be obtained. Therefore, the magnetic gap in which the magnetic bias permanent magnet is disposed needs to be 50 μm or more, and is preferably 10,000 μm or less from the viewpoint of suppressing the core size.
[0032]
Next, the required characteristics for the permanent magnet inserted into the gap are that the coercive force disappears due to the direct current magnetic field applied to the magnetic core when the intrinsic coercive force is 10 KOe or less. The larger the value is, the better. However, if it is 1 Ω · cm or more, it does not become a major factor of core loss deterioration. In addition, since the core loss characteristic deteriorates when the average maximum particle size of the powder is 50 μm or more, it is desirable that the maximum particle size of the powder is 50 μm or less. In addition, the magnet powder is oxidized during reflow of the inductance component, and this causes a significant decrease in magnetization, so that a particle size of 2.5 μm or more is necessary.
[0033]
Although there is a problem of thermal demagnetization due to heat generation of the coil, the assumed maximum use temperature of the transformer is 200.degree. C., so if Tc is 500.degree. In addition, the amount of resin must be at least 30% in volume ratio so as not to increase core loss, and inorganic glass for increasing oxidation resistance can be used for reflow work or at the maximum use temperature if the softening point is 400 ° C. or higher. The coating is not destroyed, and on the other hand, if it is 550 ° C. or lower, the problem of powder oxidation during the coating heat treatment does not appear remarkably. In addition, the effect of oxidation resistance can be obtained by adding inorganic glass. However, if the added amount exceeds 10 wt%, the improvement in DC superposition characteristics is reduced due to the increase in the amount of nonmagnetic material, so the upper limit is 10 wt%. It is good to do.
[0034]
The first embodiment of the present invention will be described below.
[0035]
(First embodiment)
As a glass powder, ZnO-B having a softening point of about 350 ° C.₂O₃-PbO (1), ZnO-B with a softening point of about 400 ° C₂O₃-PbO (2), B2O3-PbO with a softening point of about 450 ° C., K with a softening point of about 500 ° C.₂O-SiO₂-PbO, SiO having a softening point of about 550 ° C₂-B₂O₃-PbO (1), SiO having a softening point of about 600 ° C₂-B₂O₃Six types of glass powders of -PbO (2) were prepared. Each powder had a particle size of about 3 μm.
[0036]
Next, as magnet powder, Sm₂Co₁₇The magnet powder was produced by grinding from a sintered body. That is, Sm₂Co₁₇The sintered body was produced by a usual powder metallurgy method. As for the magnet characteristics, (BH) max was 28 MGOe, and the coercive force was 25 KOe. The sintered body was coarsely pulverized with a jaw crusher or a disk mill, and pulverized with a ball mill to an average particle size of about 5.0 μm.
[0037]
1% of each glass powder described above was mixed with this magnet powder, and the surface of the magnet powder was coated with glass by heat treatment in Ar at a temperature about 50 ° C. higher than the softening point of the glass powder. Next, the magnet powder thus coated and polyphenylene sulfide (PPS) as a thermoplastic resin having a volume ratio of 45 vol% were kneaded at 330 ° C. by a biaxial thermal kneader. Next, using a hot press machine, the molding temperature is 330 ° C and the pressure is 1 t / cm.²Were molded into a sheet having a height of 1.5 mm in a non-magnetic field to produce a bonded magnet. The specific resistances of these sheet-like bonded magnets all showed values of 1 Ωcm or more. This sheet-like bonded magnet was processed into the same cross-sectional shape as the central magnetic leg of the ferrite core 33 shown in FIGS.
[0038]
Here, the magnetic properties of the bonded magnet were measured by a DC BH tracer by separately preparing a test piece having a diameter of 10 mm and a thickness of t10 mm by pasting the required number of sheets of bonded magnets. As a result, it was found that an intrinsic coercive force of about 10 KOe or more was obtained for all bonded magnets.
[0039]
The ferrite core 33 is an EE core made of a general Mn—Zn ferrite material having a magnetic path length of 7.5 cm and an effective cross-sectional area of 0.74 cm. . After the bonded magnet 31 produced as described above was pulse magnetized with a magnetizing magnetic field 4T, the surface magnetic flux was measured with a gauss meter, and then inserted into the gap portion of the core 33. Next, the core loss characteristics at 100 KHz and 0.1 T were measured at room temperature with a SY-8232 AC BH tracer manufactured by Iwasaki Tsushinki. The ferrite core used for the measurement here was the same for each bonded magnet, and the core loss was measured by exchanging the magnets 31 that differ only in the type of the coated glass. The measurement results are shown in Table 1 as before heat treatment.
[0040]
Next, after passing these bonded magnets twice through a reflow furnace having a maximum temperature of 270 ° C., the surface magnetic flux and the core loss were measured in the same manner as described above.
[0041]
[Table 1]

[0042]
From Table 1, it can be seen that the surface magnetic flux decreases when the coating processing temperature exceeds 600 ° C., as can be seen from the data of the coating processing temperatures of 650 ° C. and 600 ° C. Regarding the core loss, it was found that the surface magnetic flux deteriorated after reflowing in the case of using a coating with a glass composition having a coating temperature of 400 ° C., that is, a softening point of 350 ° C. This is presumably because the glass powder having a south lower point of 350 ° C. was once coated and then remelted and peeled off during thermal kneading with the resin. On the other hand, for glass whose softening point exceeds 600 ° C., the coating treatment temperature is too high, and the demagnetization occurs due to the reduction of the magnetization contribution of the magnet powder due to oxidation of the magnet powder or reaction with the coated glass material Seem.
[0043]
Next, while superimposing a direct current of 80 (Oe) as a direct current magnetic field on a coil (indicated by 35 in FIG. 2), an inductance L when an alternating current signal is applied is measured with an LCR meter, and a core constant (dimension) is obtained. The magnetic permeability was calculated from the number of turns of the coil. As a result, the softening point was 400 ° C. (ZnO—B₂O₃-PbO (2)) to 550 ° C (SiO₂-B₂O₃The magnetic permeability of the core in which the bonded magnet including the magnetic powder coated with the glass powder of -PbO (1)) was inserted in the magnetic gap was 50 or more. On the other hand, as a comparative example, the magnetic permeability of the core when no magnet is inserted and arranged in the magnetic gap, and the glass powder (ZnO-B having a softening point of 350 ° C.₂O₃-PbO (1)) and glass powder at 600 ° C. (SiO 2₂-B₂O₃The magnetic permeability of the core in which the bonded magnet containing the magnet powder coated with -PbO (2)) was inserted and disposed in the magnetic gap was as low as 15 in all cases.
[0044]
Based on the above results, a permanent magnet having a specific resistance of 1 Ω · cm or more is inserted into the magnetic gap of the magnetic core using a magnet powder coated with glass powder having a softening point of 400 ° C. or more and 550 ° C. or less. It was found that an excellent magnetic core with excellent DC superposition characteristics and small deterioration of core loss characteristics can be obtained when it is placed.
[0045]
(Second Embodiment)
Sm used in the first embodiment₂Co₁₇Magnet powder and about 3 μm SiO with a softening point of about 500 ° C.₂-B₂O₃-PbO glass powder was mixed so that the latter weight ratio would be 0.1, 0.5, 1.0, 2.5, 5.0, 7.5, 10, 12.5 wt%, respectively. And it heat-processed in 550 degreeC Ar, and the glass coating process was carried out to the magnet powder. Next, the binder powder ZnO-B is added to these glass powder-treated magnet powders.₂O₃-PbO (2)) was mixed with a polyimide resin in a volume ratio of 50 vol%, and formed into a sheet by a doctor blade method. The solvent was dried and hot-pressed to form a thickness of 0.5 mm.
[0046]
The magnetic properties of the bonded magnet were measured in the same manner as in the first embodiment by separately preparing a test piece. As a result, each bonded magnet exhibited an intrinsic coercive force of about 10 KOe or more regardless of the amount of glass powder mixed with the magnet powder. Moreover, as a result of measuring the specific resistance, all the bonded magnets showed a value of 1 Ω · cm or more.
[0047]
Next, a sheet-like bonded magnet is magnetized in exactly the same manner as in the first embodiment, and after measuring the surface magnetic flux, it is sandwiched in the magnetic gap of the central magnetic leg of the ferrite EE core 33 shown in FIGS. Similarly to the first embodiment, alternating current and direct current were superimposed and applied to the coil 35, and the direct current superposition characteristics were measured. Further, the surface magnetic flux and the direct current superposition characteristics were measured again by passing through a reflow furnace (maximum temperature 270 ° C.) exactly the same as in the first embodiment twice. The results are shown in Table 2 for the surface magnetic flux and Table 3 for the DC superposition characteristics.
[0048]
[Table 2]

[0049]
[Table 3]

[0050]
As shown in Tables 2 and 3, it can be seen that an oxidation-resistant magnet having excellent characteristics can be obtained when the amount of glass powder added is substantially over 0 and 10 wt% or less.
[0051]
As described above, a magnetic core having a gap in at least one part of a magnetic path, and a magnetic bias magnet inserted and disposed in the magnetic gap has an intrinsic coercive force iHc of 10 KOe or more and a Curie point Tc of 500. A specific resistance comprising a bonded magnet using a rare earth magnet powder having a powder particle size of 2.5 to 50 μm at a temperature of at least ° C., the surface of the magnet powder being coated with inorganic glass, and a resin comprising at least 30% by volume of the powder By using a bonded magnet having a resistance of 1 Ωcm or more, a magnetic core excellent in direct current superposition characteristics, core loss characteristics, and oxidation resistance can be realized.
[0052]
Next, another invention of the present invention will be described.
[0053]
In the second invention of the present invention, a magnet for magnetic bias comprising a permanent magnet disposed in the vicinity of the gap in order to supply a magnetic bias from both ends of the gap to a magnetic core having a gap in at least one position of the magnetic path. In order to solve the above-mentioned problem in the magnetic core having a magnetic core, the permanent magnet has an intrinsic coercive force of 5 KOe or more and a Curie temperature of 300 ° C. or more. A magnetic core having a magnetic bias magnet in which the magnet powder is coated with inorganic glass.
[0054]
The bonded magnet as the magnetic bias magnet preferably contains the resin in a volume ratio of 30% or more and has a specific resistance of 1 Ωcm or more.
[0055]
The inorganic glass preferably has a softening point of 200 ° C. or higher and 550 ° C. or lower.
[0056]
Moreover, it is preferable that the said bond magnet contains the said inorganic glass which coat | covers the said magnet powder 10% or less by weight ratio.
[0057]
In addition, according to the present invention, an inductance component characterized in that at least one winding of one turn or more is applied to the magnetic core having the magnetic bias magnet.
[0058]
Inductance components include coils, choke coils, transformers, and other components that generally require a magnetic core and windings.
[0059]
As a result of studying the permanent magnet to be inserted in order to achieve the above object, the present invention provides excellent direct current superposition characteristics when using a permanent magnet having a specific resistance of 1 Ωcm or more and an intrinsic coercive force iHc of 5 KOe or more. In addition, it has been discovered that a magnetic core can be formed in which deterioration of core loss characteristics does not occur. This is because the magnet characteristic required to obtain an excellent DC superposition characteristic is an intrinsic coercive force rather than an energy product. Therefore, even if a permanent magnet having a low energy product is used, if the intrinsic coercive force is high, the DC characteristic is sufficiently high. This is because it has been found that superimposition characteristics can be obtained.
[0060]
A magnet having a high specific resistance and a high intrinsic coercive force is generally obtained by a rare earth bonded magnet formed by mixing rare earth magnet powder with a binder, but any composition of magnet powder having a high coercive force can be obtained. A thing is also possible. The types of rare earth magnet powders are SmCo, NdFeB, and SmFeN.
[0061]
As the magnetic core for choke coil and transformer, any material having soft magnetic properties is effective, but generally MnZn-based or NiZn-based ferrite, powder magnetic core, silicon steel plate, amorphous, etc. are used. . Further, the shape of the magnetic core is not particularly limited, and the present invention can be applied to magnetic cores having any shape such as a toroidal core, an EE core, and an EI core. A gap is provided in at least one of the magnetic paths of these cores, and a permanent magnet is inserted into the gap.
[0062]
There is no particular limitation on the gap length, but if the gap length is too narrow, the DC superimposition characteristics deteriorate, and if the gap length is too wide, the magnetic permeability decreases too much, so that the gap length to be inserted is determined naturally. The bias effect can be easily obtained if the thickness of the magnetic bias permanent magnet is large. However, the thinner the magnetic bias permanent magnet is, the better for miniaturization of the magnetic core. However, if it is smaller than 50 μm, a sufficient magnetic bias cannot be obtained. Therefore, the magnetic gap in which the magnetic bias permanent magnet is disposed needs to be 50 μm or more, and is preferably 10,000 μm or less from the viewpoint of suppressing the core size.
[0063]
Next, the required characteristics for the permanent magnet inserted into the gap are that the coercive force disappears due to the DC magnetic field applied to the magnetic core when the intrinsic coercive force is 5 KOe or less. The larger the value, the better. However, if it is 1 Ω · cm or more, it does not become a major factor for deterioration of core loss. Further, since the core loss characteristics deteriorate when the average maximum particle size of the powder is 50 μm or more, it is desirable that the maximum particle size of the powder is 50 μm or less, and when the minimum particle size is 2.0 μm or less, magnetization is caused by powder oxidation by grinding. Therefore, a particle size of 2.0 μm or more is necessary.
[0064]
In addition, there is a problem of thermal demagnetization due to heat generation of the coil, but since the assumed maximum operating temperature of the transformer is 200 ° C., if Tc is 300 ° C. or higher, there is no substantial problem. In order not to increase core loss, the amount of resin must be at least 20% by volume. Inorganic glass for increasing oxidation resistance has a softening point of 250 ° C. or higher, and its coating breaks even at the highest use temperature. On the other hand, if the temperature is 550 ° C. or lower, the problem of powder oxidation during the coating heat treatment does not appear remarkably. In addition, there is an effect of oxidation resistance by adding inorganic glass. However, when the addition amount exceeds 10 wt%, the improvement of the DC superposition characteristics is reduced due to an increase in the amount of nonmagnetic material, so the upper limit is 10 wt%. It is good to do.
[0065]
The second embodiment of the present invention will be described below.
[0066]
(Third embodiment)
As a glass powder, ZnO-B having a softening point of about 350 ° C.₂O₃-PbO (1), ZnO-B with a softening point of about 400 ° C₂O₃-PbO (2), B2O3-PbO with a softening point of about 450 ° C., K with a softening point of about 500 ° C.₂O-SiO₂-PbO, SiO having a softening point of about 550 ° C₂-B₂O₃Six types of glass powders of -PbO (1) and SiO2-B2O3-PbO (2) having a softening point of about 600 ° C were prepared. Each powder had a particle size of about 3 μm.
[0067]
Next, Sm₂Co₁₇A magnet powder prepared by pulverizing an ingot and pulverizing a sintered body produced by a general powder metallurgy method to 2.3 μm was prepared. As a result of measuring the magnetic properties of the magnet powder by VSM, the coercive force iHc was about 9 KOe.
[0068]
1% of each glass powder described above was mixed with this magnet powder, and the surface of the magnet powder was coated with glass by heat treatment in Ar at a temperature about 50 ° C. higher than the softening point of the glass powder. Next, the magnetic powder thus coated and 6 nylon as a thermoplastic resin having a volume ratio of 45 vol% were kneaded at 220 ° C. by a biaxial heat kneader. Next, using a hot press machine, the molding temperature is 220 ° C and the pressure is 0.05 t / cm.²Were molded into a sheet having a height of 1.5 mm in a non-magnetic field to produce a bonded magnet. The specific resistances of these sheet-like bonded magnets all showed values of 1 Ωcm or more. This sheet-like bonded magnet was processed into the same cross-sectional shape as the central magnetic leg of the ferrite core 33 similar to that shown in FIGS.
[0069]
Here, the magnetic properties of the bonded magnet were measured by a DC BH tracer by separately preparing a test piece having a diameter of 10 mm and a thickness of t10 mm by pasting the required number of sheets of bonded magnets. As a result, it was found that an intrinsic coercive force of about 9 KOe was obtained for all bonded magnets.
[0070]
The ferrite core 33 is an EE core made of a general MnZn-based ferrite material having a magnetic path length of 7.5 cm and an effective cross-sectional area of 0.74 cm, and a gap processing of 1.5 mm is performed on the central magnetic leg thereof. In the gap portion, the produced bonded magnet 31 was pulsed with a magnetizing magnetic field 4T, and after measuring the surface magnetic flux with a gauss meter, it was inserted and arranged. Next, the core loss characteristics at 100 KHz and 0.1 T were measured at room temperature with a SY-8232 AC BH tracer manufactured by Iwasaki Tsushinki. The ferrite core used for the measurement here was the same for each bonded magnet, and the core loss was measured by exchanging the magnets 31 that differ only in the type of the coated glass. The measurement results are shown in Table 4 as before heat treatment. Next, these bonded magnets are held in a constant temperature bath of 200 ° C. which is the assumed maximum use temperature of the transformer for 30 minutes, and the surface magnetic flux and the core loss are measured in the same manner as described above. .
[0071]
[Table 4]

[0072]
From Table 4, it can be seen that the surface magnetic flux decreases when the coating processing temperature exceeds 600 ° C., as can be seen from the data of the coating processing temperatures of 650 ° C. and 600 ° C. Regarding the core loss, no deterioration was observed in any glass composition. Therefore, for glass whose softening point exceeds 600 ° C., the coating temperature is too high, and the demagnetization occurs due to the reduction of the magnetic contribution of the magnet powder due to oxidation of the magnet powder or reaction with the coated glass material. Seem.
[0073]
Next, the DC (magnetic field 355) of the DC magnetic field of 80 (Oe) as a DC magnetic field is superimposed on the coil, and an AC signal is applied to measure the inductance L with an LCR meter. The magnetic permeability was calculated from the number of turns of the coil. As a result, the softening point was 350 ° C. (ZnO—B₂O₃-PbO (1)) to 550 ° C (SiO₂-B₂O₃The magnetic permeability of the core in which the bonded magnet including the magnetic powder coated with the glass powder of -PbO (1)) was inserted in the magnetic gap was 50 or more. On the other hand, as a comparative example, the magnetic permeability of the core when no magnet is inserted and disposed in the magnetic gap, and the glass powder (SiO 2 with a softening point of 600 ° C.₂-B₂O₃The magnetic permeability of the core in which the bonded magnet containing the magnet powder coated with -PbO (2)) was inserted and disposed in the magnetic gap was as low as 15 in all cases.
[0074]
Based on the above results, a bonded magnet using magnet powder coated with glass powder having a softening point of glass powder of 550 ° C. or less, and a permanent magnet having a specific resistance of 1 Ω · cm or more is inserted and disposed in the magnetic gap of the magnetic core. As a result, it was found that an excellent magnetic core having excellent DC superposition characteristics and small deterioration of core loss characteristics can be obtained.
[0075]
(Fourth embodiment)
SmFeN powder obtained by pulverizing 3 μm of SmFe powder produced by the reduction diffusion method as magnet powder and then nitriding was prepared. As a result of measuring the magnetic characteristics of this magnet powder by VSM, the coercive force iHc was about 8 KOe.
[0076]
Next, this magnet powder and about 3 μm ZnO—B having a softening point of about 350 ° C.₂O₃-PbO glass powder was mixed so that the latter weight ratio would be 0.1, 0.5, 1.0, 2.5, 5.0, 7.5, 10, 12.5 wt%, respectively. Then, heat treatment was performed in Ar at 400 ° C., and the magnet powder was glass-coated. Next, the glass powder-treated magnet powder is mixed with 30 vol% of an epoxy resin as a binder in a volume ratio, and a mold is formed into a sheet shape having the same cross-sectional shape as the central magnetic leg of the ferrite core 33 shown in FIGS. After molding, the resin was cured at 150 ° C. to form a bonded magnet. The magnetic properties of the bonded magnet were measured in the same manner as in the third embodiment by separately preparing a test piece. As a result, each bonded magnet exhibited an intrinsic coercive force of about 8 KOe regardless of the amount of glass powder mixed with the magnet powder. Moreover, as a result of measuring the specific resistance, all the bonded magnets showed a value of 1 Ω · cm or more.
[0077]
Next, a sheet-like bonded magnet is magnetized in exactly the same manner as in the third embodiment, and after measuring the surface magnetic flux, it is sandwiched in the magnetic gap of the central magnetic leg of the ferrite EE core 33 shown in FIGS. Similar to the third embodiment, alternating current and direct current were superimposed and applied to the coil 35, and the direct current superposition characteristics were measured.
[0078]
Furthermore, the surface magnetic flux and the direct current superimposition characteristics were measured again in the same manner as in the third embodiment, which was maintained in a 200 ° C. constant temperature bath for substantially 30 minutes. The results are shown in Table 5 for the surface magnetic flux and Table 6 for the DC superimposition characteristics.
[0079]
[Table 5]

[0080]
[Table 6]

[0081]
As shown in Tables 5 and 6, it can be seen that an oxidation-resistant magnet having excellent characteristics can be obtained when the amount of glass powder added is substantially over 0 and 10 wt% or less.
[0082]
As described above, according to the second invention of the present invention, a magnetic core having a gap in at least one position of a magnetic path, and a magnetic bias magnet inserted into the magnetic gap is provided with an intrinsic coercive force. A bonded magnet using a rare earth magnet powder having an iHc of 5 KOe or more, a Curie point Tc of 300 ° C. or more, and a powder particle size of 2.0 to 50 μm, the surface of the magnet powder being coated with inorganic glass, and at least a volume ratio with the powder By using a bonded magnet having a specific resistance of 1 Ωcm or more made of 20% or more of a resin, a magnetic core excellent in DC superposition characteristics, core loss characteristics, and oxidation resistance can be realized.
[0083]
Next, another invention of the present invention will be described.
[0084]
In the third invention of the present invention, the magnet powder is dispersed in one kind of resin selected from polyamideimide resin, polyimide resin, epoxy resin, polyphenylene sulfite resin, silicon resin, polyester resin, aromatic polyamide, and liquid crystal polymer. Thus, a thin plate magnet having a resin content of 30% or more by volume and an overall thickness of 500 μm or less is obtained.
[0085]
Here, the magnet powder preferably has an intrinsic coercive force of 10 KOe or more, Tc of 500 ° C. or more, and a powder average particle size of 2.5 to 50 μm.
[0086]
In the thin plate magnet, the magnet powder is preferably a rare earth magnet powder, and the surface gloss (glossiness) is preferably 25% or more.
[0087]
Moreover, in a thin plate magnet, it is preferable that a shaping | molding compression rate is 20% or more. The magnet powder is coated with a surface active agent.
[0088]
In the thin plate magnet of the present invention, the specific resistance is preferably 0.1 Ω · cm or more.
[0089]
Further, in the present invention, for magnetic biasing, a permanent magnet is arranged in the vicinity of the magnetic gap in order to supply a magnetic bias from both ends of the gap to a magnetic core having a magnetic gap in at least one part of the magnetic path. In the magnetic core having a magnet, the permanent magnet is a magnetic core having a magnetic bias magnet which is the above-described thin plate magnet.
[0090]
Preferably, the magnetic gap has a gap length of about 500 μm or less, and the magnetic bias magnet has a thickness of the gap length or less and is magnetized in the thickness direction.
[0091]
Furthermore, the inductance component according to the present invention is an inductance having at least one winding of one turn or more on a magnetic core having the thin plate magnet as a magnetic bias magnet, thin, good in DC superposition characteristics, and low in core loss. It is a part.
[0092]
That is, in the present invention, the possibility of using a thin plate magnet having a thickness of 500 μm or less as a permanent magnet for magnetic bias inserted in the magnetic gap of the magnetic core was examined. As a result, excellent DC superposition characteristics can be obtained when a thin plate magnet having a specific resin content of 30% or more by volume and a specific resistance of 0.1 Ω · cm or more and an intrinsic coercive force of 10 KOe or more is used. In addition, it has been found that a magnetic core can be formed in which the core loss characteristics do not deteriorate. This is because the magnet characteristic necessary for obtaining an excellent DC superposition characteristic is an intrinsic coercive force rather than an energy product. Therefore, even if a permanent magnet having a high specific resistance is used, it is sufficiently high if the intrinsic coercive force is high. This is because it has been found that DC superimposition characteristics can be obtained.
[0093]
A magnet having a high specific resistance and a high intrinsic coercive force is generally obtained by a rare earth bonded magnet formed by mixing rare earth magnet powder with a binder, but any composition of magnet powder having a high coercive force can be obtained. A thing is also possible. There are SmCo, NdFeB, and SmFeN types of rare earth magnet powders. However, considering thermal demagnetization during use such as reflow, a magnet with a Curie point Tc of 500 ° C. or higher and an intrinsic coercive force iHc of 10 KOe or higher is required. is there.
[0094]
Further, by coating the magnet powder with a surface active material, the dispersion of the powder in the molded body becomes good and the characteristics of the magnet are improved, so that a magnetic core with higher characteristics can be obtained.
[0095]
Any material having soft magnetic properties can be used as the magnetic core for the choke coil and the transformer. Generally, a MnZn-based or NiZn-based ferrite, a dust magnetic core, a silicon steel plate, an amorphous material, or the like is used. Further, the shape of the magnetic core is not particularly limited, and the present invention can be applied to magnetic cores having any shape such as a toroidal core, an EE core, and an EI core. A gap is provided in at least one of the magnetic paths of these cores, and a thin plate magnet is inserted into the gap. There is no particular limitation on the gap length, but if the gap length is too narrow, the DC superimposition characteristics deteriorate, and if the gap length is too wide, the magnetic permeability decreases too much, so that the gap length to be inserted is determined naturally. In order to reduce the overall size of the magnetic core, the gap length is suppressed to 500 μm.
[0096]
Next, the required characteristics for the thin plate magnet inserted into the gap are that the coercive force disappears due to the DC superimposed magnetic field applied to the magnetic core below 10 KOe for the intrinsic coercive force. The larger the resistance, the better, but if it is 0.1 Ω · cm or more, it will not be a major cause of core loss degradation. Also, since the core loss characteristics deteriorate when the average maximum particle size of the powder is 50 μm or more, it is desirable that the maximum particle size of the powder is 50 μm or less, and when the minimum particle size is 2.5 μm or less, the powder is subjected to powder heat treatment and reflow. Since the decrease in magnetization due to the oxidation of becomes remarkable, a particle size of 2.5 μm or more is necessary.
[0097]
Hereinafter, an embodiment of the third invention will be described.
[0098]
(Fifth embodiment)
Sm₂Co₁₇The magnet powder and the polyimide resin were heat-kneaded using a lab plast mill as a heat kneader. The amount of resin was changed from 15 vol% to 40 vol%, and each was kneaded. An attempt was made to form a thin plate magnet having a thickness of 0.5 mm using a hot press machine. As a result, it was found that the resin could not be molded unless the addition amount of the resin was 30 vol% or more. Moreover, although the result of the polyimide resin thin plate magnet is shown in the present embodiment, the same result is obtained for each of other epoxy resins, polyphenylene sulfite resins, silicon resins, polyester resins, aromatic polyamides, and liquid crystal polymers. was gotten.
[0099]
(Sixth embodiment)
Each magnet powder and various resins were thermally kneaded using a lab plast mill with the composition shown in Table 7 below. The set temperature during operation of the Laboplast mill was 5 ° C. higher than the softening point of each resin.
[0100]
[Table 7]

[0101]
Thin kneaded magnets each having a thickness of 0.5 mm were produced by molding the materials kneaded with a lab plast mill with a hot press machine in a non-magnetic field. This thin plate magnet was cut into the same cross-sectional shape as the central magnetic leg of the E-type ferrite core 33 shown in FIGS.
[0102]
Next, as shown in FIGS. 1 and 2, a 0.5 mm gap is formed in the central magnetic leg of the EE core having a magnetic path length of 7.5 cm and an effective area of 0.74 cm made of a general MnZn ferrite material. Processed. The magnetic core having the magnetic bias magnet 31 was produced by inserting and arranging the produced thin plate magnet 31 in the gap portion. In the figure, 31 is a thin plate magnet and 33 is a ferrite core. Next, after magnet 31 is magnetized in the magnetic path direction of core 33 with a pulse magnetizer, coil 35 is wound around core 33, and AC magnetic field frequency is 100 kHz, superimposed magnetic field is 0 to 200 Oe with HP-4284 LCR meter. The inductance L was measured under the following conditions. After this measurement, after holding at 270 ° C. for 30 minutes in a reflow furnace, the inductance L was measured again, and this measurement was repeated five times. The DC superimposed current is applied so that the direction of the magnetic field due to DC superposition at this time is opposite to the direction of magnetization of the magnetic bias magnet. The magnetic permeability was calculated from the obtained inductance L, the core constant (core dimensions, etc.) and the number of windings to obtain the DC superposition characteristics. DC superposition characteristics based on five measurements of each core are shown in FIGS.
[0103]
From FIG. 7, Sm₂Co₁₇It can be seen that the direct current superposition characteristics of the core in which the thin plate magnet in which the magnetic powder is dispersed in the polypropylene resin is inserted are greatly deteriorated after the second time. This is because the thin plate magnet has been deformed by reflow. In the core in which a thin plate magnet in which Ba ferrite having a coercive force of only 4 kOe is dispersed in a polyimide resin is inserted and arranged, as shown in FIG. On the contrary, the core in which a thin plate magnet using magnet powder having a coercive force of 10 kOe or more and polyimide or epoxy resin is inserted and arranged is not greatly changed even in repeated measurement, as shown in FIGS. It can be seen that it exhibits stable characteristics. From these results, it can be estimated that the Ba ferrite thin plate magnet has a small coercive force, so that the reverse magnetic field applied to the thin plate magnet causes demagnetization or magnetization reversal, and the direct current superposition characteristics deteriorate. Further, it was found that the thin plate magnet inserted into the core exhibits excellent DC superposition characteristics in a thin plate magnet having a coercive force of 10 kOe or more. Although not shown in the present embodiment, the same applies to a thin plate magnet made of a resin selected from polyphenylene sulfite resin, silicon resin, polyester resin, aromatic polyamide, and liquid crystal polymer in combinations other than the present embodiment. It was confirmed that the effect of.
[0104]
(Seventh embodiment)
Sm of 30% by volume of polyphenylene sulfite resin and magnet powder having a particle size of 1.0 μm, 2.0 μm, 25 μm, 50 μm, and 55 μm₂Co₁₇Each of the magnetic powders was heat-kneaded using a lab plast mill. Thin kneaded magnets each having a thickness of 0.5 mm were prepared by molding the materials kneaded with a lab plast mill with a hot press machine in a non-magnetic field. Next, as in the sixth embodiment, as shown in FIGS. 1 and 2, the thin plate magnet 31 is cut into the same cross-sectional shape as the central magnetic leg of the E-type ferrite core 33, as shown in FIGS. A core as shown in FIG. Next, after magnetizing the thin plate magnet 31 in the direction of the magnetic path of the core 33 with a pulse magnetizer, the coil 47 is wound around the core 45, and 300 kHz, 0.005 by a SY-8232 AC BH tracer made by Iwasaki Tsushinki. Core loss characteristics at 1T were measured at room temperature. The measurement results are shown in Table 8. From Table 8, it was found that the core loss characteristics were excellent when the average particle diameter of the magnet used in the thin plate magnet was 2.5 to 50 μm.
[0105]
[Table 8]

[0106]
(Eighth embodiment)
Sm₂Co₁₇The magnet powder 60 vol% and the polyimide resin 40 vol% were respectively heat-kneaded using a lab plast mill. The product obtained by heat kneading was subjected to a press press to change a press pressure to produce a 0.3 mm compact, and magnetized at 4T with a pulse magnetizer to produce a thin plate magnet. The gloss (glossiness) of the produced thin plate magnets was 15% to 33%, respectively, and the higher the press pressure, the higher the gloss. These molded bodies were cut into 1 cm × 1 cm, and the results of measuring the flux with the TOEI TDF-5 Digital Flexmeter and the results of measuring the gloss are shown in Table 9.
[0107]
[Table 9]

[0108]
From the results shown in Table 9, the thin plate magnet having a gloss of 25% or more has excellent magnet characteristics. This is because when the gloss of the produced thin plate magnet is 25% or more, the filling rate of the thin plate magnet is 90% or more. In addition, in the present embodiment, the result of an experiment with a polyimide resin was shown, but one type selected from other epoxy resins, polyphenylene sulfite resins, silicon resins, polyester resins, aromatic polyamides, and liquid crystal polymers. Similar results were obtained with this resin.
[0109]
(Ninth embodiment)
Volume ratio after drying is Sm₂Co₁₇Sm so that the magnet powder is 60 vol% and the polyimide resin is 40 vol%.₂Co₁₇Γ-Butyrolactone was added as a solvent to magnet powder and Rika Coat (polyimide resin) manufactured by Nippon Nippon Chemical Co., Ltd., and stirred for 5 minutes with a concentric defoamer, and kneaded with three rolls to prepare a paste. The mixing ratio of the solvent is Sm₂Co₁₇The magnetic powder and Rika Co., Ltd. made by Nippon Nippon Chemical Co., Ltd. were combined to make 10 parts by weight of γ-butyrolactone with respect to 70 parts by weight. A 500 μm green sheet was prepared from the prepared paste by a doctor blade method and dried. The dried green sheet was cut into 1 cm × 1 cm, the pressing pressure was changed and hot pressing was performed with a hot press machine, and the formed compact was magnetized at 4T with a pulse magnetizing apparatus to produce a thin plate magnet. For comparison, a compact that was not hot-pressed was also magnetized into a thin plate magnet. Moreover, this time, it produced with said compounding ratio, but as long as it can obtain the paste which can produce the green sheet with component and compounding ratio other than this, it is good. In addition, although a three-roll mill is used for kneading, a homogenizer, a sand mill, or the like may be used in addition to this. The gloss (glossiness) of the produced thin plate magnets was 9% to 28%, respectively, and the higher the press pressure, the higher the gloss. Table 10 shows the results of measuring the flux of these thin plate magnets with a TOEI TDF-5 Digital Fluxmeter. In addition, the results of measuring the compression ratio of the thin plate magnet at this time by hot pressing (= 1−thickness after hot pressing / thickness before hot pressing) are also shown side by side.
[0110]
[Table 10]

[0111]
From the above results, as in the eighth embodiment, good magnet characteristics can be obtained when the gloss is 25% or more. This is also because when the gloss is 25% or more, the filling rate of the thin plate magnet is 90% or more. Moreover, when it looked at a compression rate, it turned out that a favorable magnet characteristic is acquired with a compression rate of 20% or more.
[0112]
In this embodiment, the results of experiments with the above composition and compounding ratio were shown with polyimide resin, but other epoxy resins other than this, polyphenylene sulfite resin, silicon resin, polyester resin, aromatic polyamide, liquid crystal Similar results were obtained with a single resin selected from the polymer and the compounding ratio.
[0113]
(Tenth embodiment)
Sm₂Co₁₇Magnet powder and 0.5 wt% sodium phosphate as a surfactant were mixed. Similarly, Sm₂Co₁₇Mixing magnet powder and sodium carboxymethylcellulose 0.5wt%, Sm₂Co₁₇Magnet powder and sodium silicate were mixed. These mixed powders were each kneaded with 65 vol% and polyphenyl sulfite resin 35 vol% using a lab plast mill. What was kneaded with a lab plast mill was molded to 0.5 mm by hot pressing and cut into the same cross-sectional shape as the central magnetic leg of the E-type ferrite core 33 shown in FIGS. 1 and 2 as in the sixth embodiment. Then, the produced thin plate magnet 31 was inserted into the central magnetic leg gap portion of the EE core 33, and the core shown in FIGS. 1 and 2 was produced. Next, after magnetizing the thin plate magnet 31 in the magnetic path direction of the core 33 with a pulse magnetizer, the coil 35 is wound around the core 33, and the SY-8232 AC BH tracer manufactured by Iwasaki Tsushinki Co., Ltd. is used. The core loss characteristics at 1T were measured at room temperature. The measurement results are shown in Table 11. For comparison, Sm was used without using a surfactant.₂Co₁₇A magnet powder of 65 vol% and polyphenyl sulfite resin 35 vol% kneaded with a lab plast mill is molded into 0.5 mm by hot pressing and inserted into the magnetic gap of the central magnetic leg of the same ferrite EE core as above. After magnetizing this in the magnetic path direction of the core with a pulse magnetizer, the coil was wound and the core loss was measured. The results are also shown in Table 11.
[0114]
[Table 11]

[0115]
Table 11 shows that the addition of a surfactant exhibits good core loss characteristics. This is because the addition of a surfactant prevented aggregation of primary particles and suppressed eddy current loss. In the present embodiment, the result of adding a phosphate was shown, but even when a surfactant other than this was added, the result that the core loss characteristics were good was obtained.
[0116]
(Eleventh embodiment)
Sm₂Co₁₇After magnet powder and polyimide resin were kneaded with a lab plast mill, a thin plate magnet having a thickness of 0.5 mm was produced by press molding in a magnetic field with a hot press. Here, by adjusting the resin amount of the polyimide resin, thin plate magnets having specific resistances of 0.05, 0.1, 0.2, 0.5, and 1.0 Ω · cm, respectively, were produced. Thereafter, similarly to the sixth embodiment, it was processed into the same cross-sectional shape as the central magnetic leg of the E-type ferrite core 45 of FIGS. 1 and 2. Next, the produced thin magnet 31 is inserted into the magnetic gap of the central magnetic leg of the EE core 45 having a magnetic path length of 7.5 cm and an effective sectional area of 0.74 cm made of this MnZn-based ferrite material. After magnetizing in the road direction, the coil 35 was wound, and the core loss characteristics at 300 KHz and 0.1 T were measured at room temperature using a SY-8232 AC BH tracer manufactured by Iwasaki Tsushinki. Here, the ferrite core used for the measurement is the same, and only the magnet is replaced with one having a different specific resistance, and the result of measuring the core loss is shown in Table 12.
[0117]
[Table 12]

[0118]
From Table 12, it can be seen that a magnetic core having a specific resistance of 0.1 Ω · cm or more shows good core loss characteristics. This is because eddy current loss can be suppressed by increasing the specific resistance of the thin plate magnet.
[0119]
(Twelfth embodiment)
A sample having a thickness of 0.5 mm was prepared by kneading, forming, and processing various magnet powders and various resins with the compositions shown in Table 13, respectively, by the methods described below. Where Sm₂Co₁₇The system powder and ferrite powder are pulverized powders of sintered bodies, Sm₂Fe₁₇N powder is Sm produced by the reduction diffusion method₂Fe₁₇The powder was obtained by nitriding the powder, and each powder had an average particle size of about 5 μm. Aromatic polyamide resin (6T nylon) and polypropylene resin were heat-kneaded at 300 ° C. (polyamide) and 250 ° C. (polypropylene) in Ar using a lab plast mill, and then molded with a hot press to prepare a sample. For soluble polyimide resin, add γ-butyrolactone as a solvent and stir with a centrifugal defoamer for 5 minutes to prepare a paste, then prepare a green sheet by doctor blade method so that the finished product is 500 μm, dry, and heat press A sample was prepared. The epoxy resin was stirred and mixed in a beaker and then molded into a mold, and a sample was prepared under appropriate curing conditions. The specific resistances of these samples were all 0.1 Ωcm or more.
[0120]
This thin plate magnet was cut into a core cross-sectional shape of a ferrite core described below. The core was an EE core made of a general MnZn-based ferrite material having a magnetic path length of 5.9 cm and an effective cross-sectional area of 0.74 cm, and the core was processed with a gap of 0.5 mm. The produced thin plate magnet was inserted into the gap portion and arranged as shown in FIGS. 1 and 2 (31 is a thin plate magnet, 33 is a ferrite core, and 35 is a winding portion).
[0121]
Next, after magnetizing in the direction of the magnetic path with a pulse magnetizer, the DC permeability was measured with an HP-4284A LCR meter manufactured by Hewlett Packard, and the effective magnetic permeability of an AC magnetic field frequency of 100 KHz and a DC superimposed magnetic field of 35 Oe was measured.
[0122]
Next, these cores were held in a reflow furnace at 270 ° C. for 30 minutes, and then the DC superposition characteristics were measured again under exactly the same conditions.
[0123]
As a comparative example, the same measurement was performed for a case in which no magnet was inserted into the gap, and there was no change in characteristics before and after reflow, and the effective permeability μe was 70.
[0124]
These results are shown in Table 13, and as an example of the results, FIG. 7 shows the DC superposition characteristics of the samples (2) and (4) and the comparative example. Of course, the superimposed current is applied so that the direction of the DC bias magnetic field is opposite to the direction of magnetization of the magnet magnetized at the time of insertion.
[0125]
In addition, the core into which the polypropylene resin thin magnet was inserted could not be measured because the magnet was significantly deformed.
[0126]
It can be seen that the DC superposition characteristics are greatly deteriorated after reflow in a core in which a Ba ferrite thin plate magnet having a coercive force of only 4 KOe is inserted. Sm₂Fe₁₇It can be seen that the DC superposition characteristic is greatly deteriorated after reflowing even in the core in which the N thin plate magnet is inserted. Conversely, the coercive force is 10 KOe or more and Tc is as high as 770 ° C.₂Co₁₇It can be seen that the core in which the thin plate magnet is inserted shows no very deteriorated characteristics and exhibits very stable characteristics.
[0127]
From these results, since the Ba ferrite thin plate magnet has a small coercive force, it can be presumed that the reverse magnetic field applied to the thin plate magnet causes demagnetization or magnetization reversal, and the direct current superposition characteristics are deteriorated, and SmFeN Although the magnet has a high coercive force, Tc has a low value of 470 ° C., so thermal demagnetization occurs, and it is presumed that the characteristics deteriorated due to a synergistic effect of demagnetization by a magnetic field in the opposite direction. Therefore, it was found that the thin plate magnet inserted into the core exhibits excellent DC superposition characteristics in the thin plate magnet having a coercive force of 10 KOe or more and a Tc of 500 ° C. or more.
[0128]
Further, although not shown in the present embodiment, it was confirmed that the same effect can be obtained even in combinations other than the present embodiment even in a thin plate magnet made of the resin shown in the claims.
[0129]
[Table 13]

[0130]
(Thirteenth embodiment)
Sm exactly the same as in the twelfth embodiment₂Co₁₇A system magnet powder (iHc = 15 kOe) and a soluble polyamideimide resin (Toyobo Viromax) were kneaded with a pressure kneader, then diluted and kneaded with a planetary mixer, and stirred for 5 minutes with a centrifugal defoamer to prepare a paste. A paste was prepared by a doctor blade method so that a green sheet was prepared so that the thickness after drying was about 500 μm, dried, hot pressed, and then processed to a thickness of 0.5 mm to obtain a thin plate magnet sample. Here, the resin amount of the polyamideimide resin was prepared as shown in Table 14 so that the specific resistances were 0.06, 0.1, 0.2, 0.5, and 1.0 Ω · cm, respectively. These thin plate magnets were cut into the same core cross-sectional shape as the core of the fifth embodiment to obtain measurement samples.
[0131]
Next, the produced thin plate magnet was inserted into an EE core having the same 0.5 mm gap length as in the twelfth embodiment, and the magnet was magnetized with a pulse magnetizer. About these cores, the core loss characteristic in 300KHz and 0.1T was measured at room temperature using the SY-8232 alternating current BH tracer made from Iwasaki Tsushinki. Here, the ferrite core used for the measurement was the same, and only the magnets having different specific resistances were replaced and inserted, and the core loss characteristics were measured after being magnetized again with a pulse magnetizer.
[0132]
The results are shown in Table 14. As a comparative example, the core loss characteristic of an EE core with exactly the same gap under the same measurement conditions is 520 (KW / m³)Met. Table 14 shows good core loss characteristics with a magnetic core having a specific resistance of 0.1 Ωcm or more. This is presumably because eddy current loss can be suppressed by increasing the specific resistance of the thin plate magnet.
[0133]
[Table 14]

[0134]
(Fourteenth embodiment)
Sm (Co_0.742Fe_0.20Cu_0.055Zr_0.029)_7.7From the sintered magnet having the composition (iHc = 15 KOe), those having different average particle diameters were prepared by changing the grinding time, and then the maximum particle diameter was adjusted through sieves having different diameters.
[0135]
  Volume ratio after drying is Sm₂Co₁₇Sm so that the magnet powder becomes 60 vol 1% and the polyimide resin 40 vol%. ₂ Co ₁₇ Γ-Butyrolactone was added as a solvent to magnet powder and Rika Coat (polyimide resin) manufactured by Nihon Rika Co., Ltd., and stirred for 5 minutes with a concentric deaerator to prepare a paste. The mixing ratio of the solvent is Sm ₂ Co₁₇The magnetic powder and Rika Co., Ltd. made by Nippon Nippon Chemical Co., Ltd. were combined to make 10 parts by weight of γ-butyrolactone with respect to 70 parts by weight. The prepared paste was applied to the 500 μm grease by the DocCoublade method.TheA sheet was prepared, dried, and hot pressed. This was cut into a core shape of a ferrite core, and then magnetized at 4T using a pulse magnetizing device to produce a thin plate magnet. Table 15 shows the results of measuring the flux of these thin plate magnets with a TOEI TDF-5 Digital Flux meter. Further, as in the twelfth embodiment, the DC superposition characteristics were measured across the ferrite core, and then the bias amount was measured. The amount of bias was determined by the product of the permeability and the magnitude of the superimposed magnetic field.
[0136]
[Table 15]

[0137]
Sample {circle around (1)} having an average particle diameter of 2.1 μm has a low flux and a small amount of bias. This is considered to be because the oxidation of the magnet powder proceeds during the production process. Sample (4), which has a large average particle size, has a low powder filling rate and a low flux, and because the surface roughness of the magnet is rough, the adhesion with the core is poor and the permeance coefficient is reduced, so the bias amount is reduced. it seems to do. Further, even for a sample having a small particle size, the sample (5) with insufficient press pressure and large surface roughness has a low flux and a small bias amount because of a low powder filling rate. In addition, the sample (6) in which coarse particles are mixed is considered to have a low bias amount because the surface roughness is rough.
[0138]
From these results, when a thin plate magnet having an average particle size of magnetic powder of 25 μm or more and a maximum particle size of 50 μm and a center line average roughness of 10 μm or less is inserted, it is excellent when the thin plate magnet is inserted. It was found that it showed direct current superposition characteristics.
[0139]
(Fifteenth embodiment)
Sm₂Co₁₇In the system, the Zr content is 0.01 at% and the composition is Sm (Co_0.78Fe_0.11Cu_0.10Zr_0.01)_8.22nd generation Sm₂Co₁₇A magnet powder obtained by coarsely grinding an ingot called a magnet and then heat-treated, and a Zr content of 0.029 at% and a composition of Sm (Co_0.0742Fe_0.20Cu_0.055Zr_0.029)_8.2In general, a magnet powder obtained by roughly pulverizing an ingot having a composition called a third generation Sm2Co17 magnet was used. Second generation Sm above₂Co₁₇The magnet powder was subjected to an aging heat treatment at 800 ° C. for 1.5 hours, and the third generation Sm₂Co₁₇The magnet was subjected to an aging heat treatment at 800 ° C. for 10 hours. As a result, the coercive force of the magnet powder measured by VSM was the second generation or 8 KOe, and the third generation was 20 KOe. These coarsely pulverized powders were finely pulverized in an organic solvent by a ball mill to an average particle size of 5.2 μm, and passed through a sieve having an opening of 45 μm to obtain a magnet powder. Next, 35% by volume of epoxy resin as a binder was mixed with each of the produced magnet powders, and a bonded magnet having an EE core core shape and a thickness of 0.5 mm was produced by molding, exactly the same as in the twelfth embodiment. . Here, as a custom magnet, a test piece of φ10 × t10 was separately prepared and measured with a DC BH tracer.
[0140]
The coercive force was almost the same as that of the coarsely pulverized powder. Next, these magnets were inserted into the same EE core as in the twelfth embodiment, and after pulse magnetization and winding, the effective permeability at 100 KHz when 40 Oe DC was superimposed was measured with an LCR meter. Next, these cores were held for 1 hour in a constant temperature bath of 270 ° C., which is the condition of the reflow furnace, and then the DC superposition characteristics were measured in the same manner as described above. The results are also shown in Table 16.
[0141]
[Table 16]

[0142]
Third generation Sm with higher coercivity than Table 16₂Co₁₇When magnet powder was used, it was found that good DC superposition characteristics could be obtained even after reflow. It is known that the ratio of Sm to transition metal has a coercive force peak, but this optimum composition ratio is known to vary depending on the amount of oxygen contained in the alloy. Confirms that the ingot fluctuates between 8.0 and 8.5. From the above, Sm (Co whose composition is the third generation_bal.Fe_0.15-0.25Cu_0.05-0.06Zr_0.02-0.03)_7.0-8.5Thus, it was found that the DC superposition characteristics are good even under reflow conditions.
[0143]
(Sixteenth embodiment)
The composition produced in the sample (3) of the fourteenth embodiment is Sm (Co_0.742Fe_0.20Cu_0.055Zr_0.029)_7.7A magnetic powder having an average particle size of 5 μm and a maximum particle size of 45 μm was used. Zn, inorganic glass (ZnO-B) on the surface of the magnet powder₂O₃-PbO) softening point 400 ° C, after Zn further inorganic glass (ZnO-B₂O₃A thin plate magnet coated with -PbO) was produced in the same manner as the sample (2) of the thirteenth embodiment, and the DC superposition characteristics of the Mn-Zn ferrite core into which the magnet was inserted were the twelfth embodiment. Table 17 shows the results of comparison and determination of the bias amount after measurement, and the core loss characteristics measured by the same method as in the thirteenth embodiment.
[0144]
Here, Zn was heat-treated for 2 hours in an Ar atmosphere at 500 ° C. after being mixed with the magnet powder. ZnO-B₂O₃-PbO was heat-treated by the same method except that the heat treatment temperature was 450 ° C. On the other hand, in order to form a composite layer, first, Zn and magnet powder are mixed and heat-treated at 500 ° C., and once taken out of the furnace, this powder and ZnO—B₂O₃-After PbO powder is mixed, heat treatment is performed at 450 ° C. These powders were mixed with an amount of bainter (epoxy resin) corresponding to 45 vol% of the total volume, and then molded in a magnetic field. The molded body has the same core cross-sectional shape as the twelfth embodiment and a height of 0.5 mm, and is magnetized with a pulse magnetic field of about 10 T after being inserted into the core. The DC superposition characteristics and the core loss characteristics were measured by the same method as in the thirteenth embodiment. Next, after these cores were held at a constant temperature bath of 270 ° C. for 30 minutes, DC superposition characteristics and core loss characteristics were similarly measured. As a comparative example, Table 17 also shows the results of measuring the properties of the uncoated powder after the molded body was prepared by the same method.
[0145]
The uncoated material is greatly deteriorated in DC superposition characteristics and core loss characteristics by heat treatment, but the coating rate of Zn, inorganic glass, and its composite is much smaller than that of uncoated material. I understand. This can be presumed to be because the oxidation of the magnet powder was suppressed by the coating.
[0146]
It can also be seen that the mixture of the coating material of 10 vo 1% or more has a low effective magnetic permeability, and the magnitude of the bias magnetic field by the magnet is much smaller than that of the other. This is presumably because the proportion of the magnet powder decreased because the amount of the covering material increased, or because the magnitude of magnetization decreased due to the reaction between the magnet powder and the covering material. Accordingly, it was found that the coating amount is very excellent in the range of 0.1 to 10 wt%.
[0147]
[Table 17]

[0148]
(Seventeenth embodiment)
Sm of sample (3) of the fourteenth embodiment₂Co₁₇Using a magnetic powder, 50% by volume of epoxy resin was mixed as a binder, and then molded in the vertical direction of the middle foot in a 2T magnetic field to produce an anisotropic magnet. Moreover, what was die-molded in a magnetic field as a comparative example was similarly produced. Next, each of these bonded magnets is inserted into a MnZn-based ferrite material in the same manner as in the twelfth embodiment, pulse magnetization and winding are performed, DC superposition characteristics are measured with an LCR meter, and the core constant and the number of windings are measured. From this, the magnetic permeability was calculated. The results are shown in Table 18.
[0149]
Further, the sample after the measurement was held at a constant temperature bath of 270 ° C., which is a reflow condition, for 1 hour, cooled to room temperature, and the DC superposition custom order was measured with an LCR meter in the same manner as described above. The results are also shown in Table 18.
[0150]
From Table 18, it was found that good results were obtained before and after reflowing compared to the magnetic fieldless magnet.
[0151]
[Table 18]

[0152]
  (Eighteenth embodiment)
  Sm of sample (3) of 14th embodiment₂Co₁₇The process is exactly the same as in the twentieth embodiment up to the point where a magnet powder is used and 50% by volume of epoxy resin is mixed as a binder and then a die is molded in a magnetic field to produce a 0.5 mm thick magnet. Next, as in the twelfth embodiment, it was inserted into a MnZn ferrite material and magnetized. The magnetic field at this time is 1T, 2T,2.5Magnetization was performed at T, 3T, 5T, and 10T. 1T, 2T, and 25T were magnetized with an electromagnet, and 3T, 5T, and 10T were magnetized with a pulse magnetizer. Thereafter, the DC superimposed physical properties were measured with an LCR meter, and the magnetic permeability was calculated from the core constant and the number of windings. The bias amount is obtained from the result by the method obtained in the seventeenth embodiment, and the result is shown in FIG.
[0153]
  From FIG.2.5It has been found that good superposition characteristics cannot be obtained unless the temperature is T or more.
[0154]
(Nineteenth embodiment)
Referring to FIGS. 10 and 11, in the inductance component to which the thin plate magnet according to the nineteenth embodiment of the present invention is applied, the core 39 to be used is made of MnZn-based ferrite material and has a magnetic path length of 2.46. Area 0.394cm₂The EE type magnetic core is formed. As shown in FIG. 11, after a mold coil (resin-sealed winding (4 turns)) is incorporated into the E-type core 39, it is further processed into the same shape as the cross-sectional area of the middle leg of the E-type core 39. The thin plate magnet 43 having a thickness of 0.16 mm is disposed in the core cap portion and is swallowed by the core 39 on the other side to function as an inductance component.
[0155]
It is assumed that the magnetizing direction of the thin magnet 43 is magnetized in the direction opposite to the magnetic field generated by the molded coil.
[0156]
The DC superimposed inductance characteristics when the thin magnet is applied and the DC superimposed inductance characteristics when the thin magnet is not applied are measured, and the results are shown in 45 (the former) and 47 (the latter) in FIG.
[0157]
Further, after passing through a reflow furnace (peak temperature: 270 ° C.), the DC superimposed inductance characteristics were measured in the same manner as above, and as a result, it was confirmed that the results were the same as before the reflow.
[0158]
(20th embodiment)
Referring to FIGS. 13 and 14, in the twentieth embodiment of the present invention, the core to be used is made of a MnZn-based ferrite material as in the nineteenth embodiment and has a magnetic path length of 2.46 cm and an effective sectional area. A 0.394 cm magnetic core is formed, but an EI type magnetic core is formed and functions as an inductance component. The assembly process is the same as in the nineteenth embodiment, but the shape of the ferrite core 53 on one side is the I type.
[0159]
The DC superimposed inductance characteristic using the thin magnet and the DC superimposed inductance characteristic after passing through the reflow furnace are the same as in the nineteenth embodiment.
[0160]
(Twenty-first embodiment)
Referring to FIGS. 15 and 16, in the inductance component to which the thin plate magnet according to the twenty-first embodiment of the present invention is applied, the core 65 to be used is made of a MnZn-based ferrite material and has a magnetic path length of 0.02 m and an effective interruption. Area 5 × 10^-6A UU type magnetic core of cm is formed. As shown in FIG. 16, when the coil 67 is wound around the bobbin 63 and the pair of U-shaped cores 65 are assembled, a thin plate magnet 69 having a thickness of 02 mm that is processed to have the same shape as the cross-sectional area (joint portion) of the U-shaped core 65. Is disposed in the core gap portion. Thereby, the permeability 4 × 10^-3It functions as an H / m inductance component.
[0161]
It is assumed that the magnetizing direction of the thin magnet 69 is magnetized in the direction opposite to the magnetic field generated by the coil.
[0162]
The DC superimposed inductance characteristics when the thin magnet is applied and the DC superimposed inductance characteristics when the thin magnet is not applied are measured, and the results are shown in 71 (the former) and 73 (the latter) in FIG.
[0163]
The result of the DC superimposed inductance characteristic is generally equivalent to showing an increase in the used magnetic flux density (ΔB) of the core forming the magnetic core (supplemented by FIG. 18, 75 in FIG. 18 is a conventional inductance component) 18 shows the use area of the core of the inductance component in which thin magnets according to the present invention are used together, and these figures show the results 71, 77, 73 and 75 of the DC superimposed inductance characteristics. A general theoretical expression of the inductance component (corresponding to each of the above) is expressed by the following equation (1).
[0164]
[Expression 1]

[0165]
From the equation (1), the effect of increasing the magnetic flux density (ΔB) is proportional to the reciprocal of the number of turns N and the effective area Ae of the magnetic core, and the former reduces the copper loss by reducing the number of turns of the inductance component. The latter contributes to the miniaturization of the core that forms the magnetic core, and the latter contributes to the miniaturization of the inductance component together with the miniaturization by reducing the number of turns. it is obvious. In the transformer, since the number of primary and secondary coil turns can be reduced, the effect is great.
[0166]
Furthermore, although the formula regarding output power is shown in Formula 2, it can be said from this formula that the effect of expanding the used magnetic flux density (ΔB) also acts on the effect of increasing the output power.
[0167]
[Expression 2]

[0168]
Further, regarding the reliability of the inductance component, after passing through a reflow furnace (peak temperature 270 ° C.), the DC superimposed inductance characteristics were measured in the same manner as described above, and as a result, it was confirmed that the results were the same as before the reflow.
[0169]
(Twenty-second embodiment)
Referring to FIGS. 19 and 20, in the inductance component to which the thin plate magnet according to the twenty-second embodiment of the present invention is applied, the core to be used is made of a MnZn-based ferrite material as in the twenty-first embodiment, and is a magnetic path. 0.02m long, effective area 5 × 10^-6m²Or a UI type magnetic core to function as an inductance component. As shown in FIG. 20, the coil 83 is wound around the bobbin 85, the I-type core 87 is assembled into the bobbin 85, and then processed into the same shape as the cross-sectional area (joint portion) of the U-type core 89. The thin plate magnets 91 are arranged one on each of the wings of the bobbin around which the coil is wound (the part where the I-type core 87 protrudes from the bobbin) (two on both wings), and the U-shaped core 89 is incorporated to complete the process. .
[0170]
The DC superimposed inductance characteristic using a thin magnet and the DC superimposed inductance characteristic after the reflow furnace is charged are not different from those in the twenty-first embodiment.
[0171]
(Twenty-third embodiment)
Referring to FIGS. 21 and 22, in the inductance component to which the thin plate magnet according to the twenty-third embodiment of the present invention is applied, the four I-type cores 95 to be used are made of silicon steel and have a magnetic path length of 0. 2m, effective area 1 × 10^-4m²This forms a mouth-shaped magnetic core. As shown in FIG. 21, two I-type cores 95 are inserted into two coils 99 each provided with insulating paper 97, so that a magnetic path with a square shape is formed. Assemble. A thin plate magnet 123 according to the present invention is arranged at the joint, and the permeability is 2 × 10.^-2An H / m-shaped magnetic path is formed to function as an inductance component.
[0172]
It is assumed that the magnetizing direction of the thin magnet 101 is magnetized in the direction opposite to the magnetic field generated by the coil.
[0173]
The DC superimposed inductance characteristics when the thin magnet is applied and the DC superimposed inductance characteristics when the thin magnet is not applied are measured for comparison, and the results are shown in 1103 (the former) and 105 (the latter) in FIG.
[0174]
The result of the DC superimposed inductance characteristic is equivalent to the fact that generally the used magnetic flux density (ΔB) of the core forming the magnetic core is enlarged (supplemented by FIG. 24, 107 in FIG. 24 is a conventional inductance component) 24 shows the use area of the core of the inductance component to which the thin magnet according to the present invention is applied, and these figures show the results 103 and 105, 109 and 107 of the DC superimposed inductance characteristics. The general theoretical formula of the inductance component is represented by the following formula (3).
[0175]
[Equation 3]

[0176]
From the equation (3), the effect of increasing the magnetic flux density (ΔB) is proportional to the reciprocal of the number of turns N and the effective cross-sectional area Ae of the magnetic core, and the former reduces the copper loss by reducing the number of turns of the inductance component. The latter contributes to the miniaturization of the core that forms the magnetic core, and the latter contributes to the miniaturization of the inductance component together with the miniaturization by reducing the number of turns. it is obvious. In the transformer, since the number of primary and secondary coil turns can be reduced, the effect is great.
[0177]
Furthermore, although the formula regarding output power is shown in Formula 4, it can be said from this formula that the effect of expanding the used magnetic flux density (ΔB) also acts on the effect of increasing the output power.
[0178]
[Expression 4]

[0179]
Further, regarding the reliability of the inductance component, after passing through a reflow furnace (peak temperature 270 ° C.), the DC superimposed inductance characteristics were measured in the same manner as described above, and as a result, it was confirmed that the results were the same as before the reflow.
[0180]
(24th Embodiment)
Referring to FIG. 25 and FIG. 26, in the inductance component to which the thin plate magnet according to the twenty-fourth embodiment of the present invention is applied, the round core 113, the I-type core 115, and the coil 117 having concave recesses are wound. It is composed of a lined bobbin 119 and a thin plate magnet 121. As shown in FIG. 26, the thin plate magnet 121 is disposed at the concave recess of the round core 113, that is, at the joint between the round core 113 and the I core 115.
[0181]
The mouth-shaped core 113 and the I-type core 115 used here are MnZn-based ferrite materials, a magnetic path length of 6.0 cm, and an effective cross-sectional area of 0.1 cm.²The sun-shaped magnetic core is formed.
[0182]
The thin plate magnet 121 has a thickness of 0.25 mm and a cross-sectional area of 0.1 cm.²It is assumed that the magnetic field is opposite to the magnetic field generated by the coil.
[0183]
The coil 117 is wound by 18 turns, and the DC superimposed inductance characteristics of this inductance component and the DC superimposed inductance characteristics when a thin magnet is not applied for comparison are measured, and the results are shown as 123 (the former) and 125 (the former) in FIG. The latter).
[0184]
Further, after passing through a reflow furnace (peak temperature: 270 ° C.), the DC superimposed inductance characteristics were measured in the same manner as above, and as a result, it was confirmed that the results were the same as before the reflow.
[0185]
(25th embodiment)
Referring to FIGS. 28 and 29, the inductance component to which the thin plate magnet according to the twenty-fifth embodiment of the present invention is applied has the coil 131 wound around the convex core 135 and the upper surface of the convex portion of the convex core 135. A thin plate magnet 133 having the same shape (0.07 mm) as the upper surface of the convex portion and having a thickness of 120 μm is arranged and covered with a cylindrical cap core 129.
[0186]
The convex core 135 and the cylindrical cap core 129 used here are NiZn ferrite materials, the magnetic path length is 1.85 cm, and the effective cross-sectional area is 0.07 cm.²The magnetic core is formed.
[0187]
Further, it is assumed that the thin plate magnet 133 is magnetized in the direction opposite to the magnetic field generated by the coil.
[0188]
The coil 131 is wound by 15 turns, and the DC superimposed inductance characteristics of this inductance component and the DC superimposed inductance characteristics when a thin magnet is not applied for comparison are measured, and the results are shown as 139 (the former) and 141 ( The latter).
[0189]
Further, after passing through a reflow furnace (peak temperature: 270 ° C.), the DC superimposed inductance characteristics were measured in the same manner as above, and as a result, it was confirmed that the results were the same as before the reflow.
[0190]
As described above, according to the third invention of the present invention, a thin plate magnet of 500 μm or less can be obtained, and by using this thin magnet as a magnetic bias magnet, the DC superposition characteristics of the magnetic core at a high frequency can be improved with a small size. In addition, it is possible to provide a magnetic core that does not deteriorate in characteristics even at a reflow temperature, and an inductance element that enables surface mounting without fear of deterioration in characteristics due to reflow using the magnetic core.
[0191]
【The invention's effect】
As described above, in the present invention, a magnetic core having a gap in at least one location of a magnetic path, and a magnetic bias magnet inserted and arranged in the magnetic gap has an intrinsic coercive force iHc of 10 KOe or more. A bonded magnet using a rare earth magnet powder having a Curie point Tc of 500 ° C. or higher and a powder particle diameter of 2.5 to 50 μm is coated with inorganic glass, and at least 30% by volume with the powder By using a bonded magnet made of a resin having a specific resistance of 1 Ωcm or more, a magnetic core excellent in DC superposition characteristics, core loss characteristics, and oxidation resistance can be provided.
[0192]
In the present invention, a magnetic core having a gap in at least one magnetic path and having a magnetic bias magnet inserted and disposed in the magnetic gap has an intrinsic coercive force iHc of 5 KOe or more and a Curie point Tc of 300. A specific resistance comprising a bonded magnet using a rare earth magnet powder having a powder particle diameter of 2.0 to 50 μm at a temperature of at least ° C., the surface of the magnet powder being coated with inorganic glass, and a resin comprising at least 20% by volume of the powder. By using a bonded magnet having a resistance of 1 Ωcm or more, it is possible to provide a magnetic core having excellent direct current superposition characteristics, core loss characteristics, and oxidation resistance.
[0193]
Further, in the present invention, a thin plate magnet having a thickness of 500 μm or less is obtained. By using this thin magnet as a magnetic bias magnet, the DC superposition characteristics of the magnetic core at a high frequency are improved and the characteristics are deteriorated even at a reflow temperature. By using this magnetic core, it is possible to provide an inductance component that can be surface-mounted without fear of deterioration of characteristics by reflow.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example before winding of a choke coil according to an embodiment of the present invention.
FIG. 2 is a side view of the choke coil of FIG.
FIG. 3 shows Sm in the sixth embodiment of the present invention.₂Co₁₇It is a figure which shows the measurement data of the direct current | flow superimposition characteristic of the thin-plate magnet which consists of a magnet and a polyimide resin.
FIG. 4 shows Sm in the sixth embodiment of the present invention.₂Co₁₇It is a figure which shows the measurement data of the direct current superimposition characteristic of the thin-plate magnet which consists of a magnet and an epoxy resin.
FIG. 5 shows Sm in the sixth embodiment of the present invention.₂Co₁₇It is a figure which shows the measurement data of the DC superimposition characteristic of the thin-plate magnet which consists of N magnet and a polyimide resin.
FIG. 6 is a diagram showing measurement data of direct current superposition characteristics of a thin plate magnet made of a Ba ferrite magnet and a polyimide resin in a sixth embodiment of the present invention.
FIG. 7 shows Sm in the sixth embodiment of the present invention.₂Co₁₇It is a figure which shows the measurement data of the direct current superimposition characteristic of the thin-plate magnet which consists of a magnet and a polypropylene resin.
FIG. 8 is a diagram showing measurement data of DC superposition characteristics before and after reflow in the case of using a thin plate magnet made of samples 2 and 4 and in the case of not using a thin plate magnet in the twelfth embodiment of the present invention. .
FIG. 9 is a diagram showing a magnetization magnetic field and DC superposition characteristics of an Sm2Co17 magnet-epoxy resin thin plate magnet in an eighteenth embodiment of the present invention.
FIG. 10 is an external perspective view showing an inductance component to which a thin plate magnet according to a nineteenth embodiment of the present invention is applied.
11 is an exploded perspective view of the inductance component shown in FIG. 10;
FIG. 12 is a diagram showing measurement results of DC superimposed inductance characteristics when a thin magnet according to a nineteenth embodiment of the present invention is applied and DC superimposed inductance characteristics when a thin magnet is not applied as a comparison;
FIG. 13 is an external perspective view showing an inductance component to which a thin plate magnet according to a twentieth embodiment of the present invention is applied.
14 is an exploded perspective view of the inductance component shown in FIG. 13;
FIG. 15 is an external perspective view showing an inductance component to which a thin plate magnet according to a twenty-first embodiment of the present invention is applied.
16 is an exploded perspective view of the inductance component shown in FIG. 15;
FIG. 17 is a diagram illustrating a measurement result of a DC superimposed inductance characteristic when the thin magnet according to the twenty-first embodiment of the present invention is applied and a DC superimposed inductance characteristic when the thin magnet is not applied as a comparison;
FIG. 18A is a diagram showing a core usage region of a conventional inductance component.
(B) is a figure which shows the core use area | region of an inductance component at the time of applying the thin magnet by the 22nd Embodiment of this invention.
FIG. 19 is an external perspective view showing an inductance component to which a thin plate magnet according to a twenty-second embodiment of the present invention is applied.
20 is an exploded perspective view of the inductance component shown in FIG. 19;
FIG. 21 is an external perspective view showing an inductance component to which a thin plate magnet according to a twenty-third embodiment of the present invention is applied.
22 is an exploded perspective view of the inductance component of FIG. 21. FIG.
FIG. 23 is a diagram showing a measurement result of a DC superimposed inductance characteristic when a thin magnet is applied and a DC superimposed inductance characteristic when a thin magnet is not applied as a comparison.
FIG. 24 (a) is a diagram showing a use area of a core for a conventional inductance component.
(B) is a figure which shows the use area | region of the core of the inductance component to which the thin-plate magnet by the 23rd Embodiment of this invention is applied.
FIG. 25 is an external perspective view showing an inductance component to which a thin plate magnet according to a twenty-fourth embodiment of the present invention is applied.
26 is a structural perspective view of a core and a thin plate magnet that form a magnetic path of the inductance component of FIG. 25. FIG.
FIG. 27 is a diagram showing the measurement results of the inductance characteristics when the thin plate magnet of the present invention is applied and the DC superimposed inductance characteristics when the thin magnet is not applied as a comparison.
FIG. 28 is a sectional view of an inductance component to which a thin plate magnet according to a twenty-fifth embodiment of the present invention is applied.
29 is a structural perspective view of a core and a thin plate magnet that form a magnetic path of the inductance component of FIG. 28. FIG.
FIG. 30 is a diagram showing a measurement result of a DC superimposed inductance characteristic of an inductance component according to a twenty-fifth embodiment of the present invention and a DC superimposed inductance characteristic when a thin magnet is not applied as a comparison.
[Explanation of symbols]
31 Magnet
33 core
35 coils
37 Inductance parts
39 core
41 coils
43 Magnet
51 Inductance parts
53 core
55 core
59 Magnet
61 Inductance parts
63 Bobbins
65 core
67 Winding (coil)
69 Magnet
81 Inductance parts
83 coils
85 bobbins
87 core
89 core
91 magnet
93 Inductance parts
95 core
97 Insulating paper
101 magnet
111 Inductance parts
113 core
115 core
117 coil
119 bobbin
121 magnet
127 Inductance component
129 core
131 coils
133 Magnet
135 core
137 terminal

Claims (53)

A bonded magnet in which magnet powder is dispersed in a resin, and has a specific resistance of 1 Ω · cm or more. The magnet powder has an intrinsic coercive force of 5 KOe or more, a Curie point Tc of 300 ° C. or more, and a powder particle size of 150 μm. It does from those of the powder is less coated with inorganic glass Ri, permanent magnet, characterized in that it contains less than 10% of the inorganic glass by weight. The permanent magnet according to claim 1 , wherein the magnet powder has an average particle size of 2.0 to 50 μm. The permanent magnet according to claim 1 , wherein the magnet powder has an average particle size of 2.5 to 25 μm and a maximum particle size of 50 μm. The permanent magnet according to claim 1 , wherein the inorganic glass has a softening point of 220 ° C. to 500 ° C. The permanent magnet according to claim 1 , wherein the resin content is 20% or more by volume ratio. The permanent magnet according to claim 1 , wherein the magnet powder is a rare-earth magnet powder. The permanent magnet according to claim 1 , wherein a molding compression rate is 20% or more. The permanent magnet according to claim 1 , wherein the magnet powder has an average particle size of 2.5 to 50 μm. The permanent magnet according to claim 1 , wherein the magnet powder has an intrinsic coercive force of 10 KOe or more and a Curie point Tc of 500 ° C. or more. The permanent magnet according to claim 9 , wherein the inorganic glass has a softening point of 400 ° C. to 550 ° C. The permanent magnet according to claim 9 , wherein the resin content is 30% or more by volume ratio. The permanent magnet according to claim 9 , wherein the magnet powder is a rare earth magnet powder. The permanent magnet according to claim 9 , wherein a molding compression rate is 20% or more. The permanent magnet according to claim 1 , wherein the total thickness is 10,000 μm or less. The permanent magnet according to claim 14 , wherein the total thickness is 500 μm or less. The thin magnet according to claim 1 , wherein the magnetizing magnetic field is 2.5T. The permanent magnet according to claim 1 , wherein the center line average roughness Ra is 10 μm or less. The permanent magnet according to claim 1 , wherein the permanent magnet is manufactured by molding. The permanent magnet according to claim 1 , wherein the permanent magnet is manufactured by hot pressing. 2. The permanent magnet according to claim 1 , wherein the permanent magnet is manufactured from a mixed paint of resin and magnet powder by a film forming method such as a doctor blade method or a printing method. The permanent magnet according to claim 1 , wherein the surface has a gloss (glossiness) of 25% or more. 2. The permanent magnet according to claim 1 , wherein the resin is at least one selected from polypropylene resin, 6-nylon resin, 12-nylon resin, polyimide resin, polyethylene resin, and epoxy resin. . 2. The permanent magnet according to claim 1 , wherein the resin is at least one selected from a polyimide resin, a polyamideimide resin, an epoxy resin, a polyphenylene sulfide resin, a silicon resin, a polyester resin, an aromatic polyamide resin, and a liquid crystal polymer. A permanent magnet characterized by that. The permanent magnet according to claim 6 , wherein the magnet powder is a rare earth magnet powder selected from SmCo, NdFeB, and SmFeN. The permanent magnet according to claim 24 , wherein the magnet powder is an Sm-Co magnet. The permanent magnet of claim 25, wherein the SmCo rare earth magnet _{powder, Sm (Co bal Fe 0.15~0.25 Cu} 0.05~0.06 Zr 0.02~0.03) 7.0~ A permanent magnet, which is an alloy powder represented by _8.5 .   A magnetic core having a magnetic bias magnet disposed in the vicinity of the magnetic gap in order to supply a magnetic bias from both ends of the gap to a magnetic core having a magnetic gap at least at one location in the magnetic path. A magnetic core having a magnet for magnetic bias, wherein the magnetic core is a permanent magnet according to claim 1.   In order to supply a magnetic bias from both ends of the gap to a magnetic core having a magnetic gap in at least one location of the magnetic path, the magnetic gap has a magnetic bias magnet disposed in the vicinity of the magnetic gap. A magnetic core having a gap length of 50 to 10,000 μm, wherein the magnetic bias magnet is the permanent magnet according to claim 17. 29. The magnetic core having a magnetic bias magnet according to claim 28 , wherein the magnetic gap has a gap length greater than about 500 [mu] m, and the magnetic bias magnet has a thickness corresponding to the magnetic gap length. And magnetic core. 29. The magnetic core having a magnetic bias magnet according to claim 28 , wherein the magnetic gap has a gap length of about 500 [mu] m or less, and the magnetic bias magnet has a thickness corresponding to the magnetic gap length. And magnetic core. An inductance component comprising at least one winding of one turn or more on a magnetic core having the magnetic bias magnet according to claim 28 . A magnetic core having a magnetic gap having a gap length of about 50 to 10000 μm at least at one location of the magnetic path, and a magnetic bias magnet disposed in the vicinity of the magnetic gap to supply a magnetic bias from both ends of the magnetic gap; An inductance component having a coil winding wound around the magnetic core for at least one turn,
The magnetic bias magnet is a bonded magnet having a specific resistance of 1 Ω · cm or more and having a resin and magnet powder dispersed in the resin.
The magnet powder consists of a rare earth magnet powder having an intrinsic coercive force of 5 KOe or more, a Curie point of 300 ° C. or more, a maximum particle size of 150 μm, and an average particle size of 2 to 50 μm coated with inorganic glass. The Sm—Co magnet powder, the Nd—Fe—B magnet powder, and the Sm—Fe—N magnet powder are selected, and the bonded magnet contains the inorganic glass in a weight ratio of 10% or less. An inductance component characterized by that. 33. The inductance component according to claim 32 , wherein the permanent magnet for bias is formed by molding. 34. The inductance component according to claim 33 , wherein the bias permanent magnet has a molding compression ratio of 20% or more. The inductance component according to claim 32 , wherein the inorganic glass has a softening point of 220 ° C to 550 ° C. 33. The inductance component according to claim 32 , wherein the resin content is 20% or more by volume, and the resin is polypropylene resin, 6-nylon resin, 12-nylon resin, polyimide resin, polyethylene resin, epoxy resin. An inductance component that is at least one selected from resins. A magnetic core having a magnetic gap having a gap length of about 50 to 10000 μm at least at one location of the magnetic path, and a magnetic bias magnet disposed in the vicinity of the magnetic gap to supply a magnetic bias from both ends of the magnetic gap; And an inductance component having a coil winding wound around the magnetic core for at least one turn and subjected to solder reflow processing.
The magnetic bias magnet is a bonded magnet having a specific resistance of 1 Ω · cm or more and having a resin and magnet powder dispersed in the resin.
The magnet powder is an Sm—Co rare earth magnet powder having an intrinsic coercive force of 10 KOe or more, a Curie point of 500 ° C. or more, a maximum particle size of 150 μm, and an average particle size of 2.5 to 50 μm, and coated with inorganic glass. Tona is, the bonded magnet inductance component characterized by containing 10% or less of the inorganic glass by weight. 38. The inductance component according to claim 37 , wherein the biasing permanent magnet is formed by molding. 39. The inductance component according to claim 38 , wherein the bias permanent magnet has a molding compression ratio of 20% or more. In the inductance component according to claim 37, wherein the SmCo rare earth magnet _{powder, Sm (Co bal Fe 0.15~0.25 Cu} 0.05~0.06 Zr 0.02~0.03) 7.0~ An inductance component characterized by being an alloy powder represented by _8.5 . The inductance component according to claim 37 , wherein the inorganic glass has a softening point of 220 ° C to 500 ° C. 38. The inductance component according to claim 37 , wherein the resin content is 30% or more by volume, and the resin is polyimide resin, polyamideimide resin, epoxy resin, polyphenylene sulfide resin, silicon resin, polyester resin, aromatic An inductance component comprising at least one selected from a group polyamide resin and a liquid crystal polymer. A magnetic core having a magnetic gap having a gap length of about 500 μm or less at least at one location of the magnetic path, and a magnetic bias magnet disposed in the vicinity of the magnetic gap to supply a magnetic bias from both ends of the magnetic gap; An inductance component having a coil winding wound around the magnetic core for at least one turn;
The magnetic bias magnet is a bonded magnet having a specific resistance of 0.1 Ω · cm or more and a thickness of 500 μm or less having a resin and magnet powder dispersed in the resin.
The magnet powder is a rare earth magnet powder having an intrinsic coercive force of 5 KOe or more, a Curie point of 300 ° C. or more, a maximum particle size of 150 μm, and an average particle size of 2.0 to 50 μm. , Nd-Fe-B magnetic powder, and Sm-Fe-N with those selected from among the magnet powder, Ri Do from those covered by the inorganic glass, wherein the bonded magnet is the inorganic glass at a weight ratio of 10 Inductance components characterized by containing no more than% . 44. The inductance component according to claim 43 , wherein the biasing permanent magnet is molded from a mixture of resin and magnet powder by a film forming method such as a doctor blade method or a printing method. 44. The inductance component according to claim 43 , wherein the bias permanent magnet has a molding compression ratio of 20% or more. 44. The inductance component according to claim 43 , wherein the inorganic glass has a softening point of 220 [deg.] C. to 500 [deg.] C. 44. The inductance component according to claim 43 , wherein the content of the resin is 20% or more by volume, and the resin includes polypropylene resin, 6-nylon resin, 12-nylon resin, polyimide resin, polyethylene resin, epoxy resin. An inductance component that is at least one selected from resins. A magnetic core having a magnetic gap having a gap length of about 500 μm or less in at least one location of the magnetic path; and a magnetic bias magnet disposed in the vicinity of the magnetic gap to supply a magnetic bias from both ends of the magnetic gap; In an inductance component having a coil winding wound around the magnetic core for at least one turn and subjected to solder reflow processing,
The magnetic bias magnet is a bonded magnet having a specific resistance of 0.1 Ω · cm or more and a thickness of 500 μm or less having a resin and magnet powder dispersed in the resin.
The magnet powder is an Sm— Co rare earth magnet powder having an intrinsic coercive force of 10 KOe or more, a Curie point of 500 ° C. or more, a maximum particle size of 150 μm, and an average particle size of 2.5 to 50 μm and coated with inorganic glass. The bond magnet contains the inorganic glass in a weight ratio of 10% or less . 49. The inductance component according to claim 48 , wherein the biasing permanent magnet is formed from a mixture of resin and magnet powder by a film forming method such as a doctor blade method or a printing method. 49. The inductance component according to claim 48 , wherein the bias permanent magnet has a molding compression ratio of 20% or more. 49. The inductance component according to claim 48 , wherein the inorganic glass has a softening point of 220 [deg.] C. to 500 [deg.] C. In the inductance component according to claim 48, wherein the SmCo rare earth magnet _{powder, Sm (Co bal Fe 0.15~0.25 Cu} 0.05~0.06 Zr 0.02~0.03) 7.0~ An inductance component characterized by being an alloy powder represented by _8.5 . 49. The inductance component according to claim 48 , wherein the resin content is 30% or more by volume, and the resin is polyimide resin, polyamideimide resin, epoxy resin, polyphenylene sulfide resin, silicon resin, polyester resin, aromatic An inductance component comprising at least one selected from a group polyamide resin and a liquid crystal polymer.

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