JP3920428B2 - Plating film and manufacturing method thereof - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、各種の薄膜磁気デバイス、例えば薄膜インダクタ、薄膜トランス等、さらに特に１０ＭＨｚ以上の高周波で使用される薄膜デバイスに用いることができる磁性めっき膜およびその製造方法に関する。
【０００２】
【従来の技術】
薄膜磁気デバイスにおいては、その使用周波数が上昇するに従い、渦電流損失が大きな問題となる。この問題を解決するために、鉄、コバルト等の磁性金属相と酸化物高比抵抗相とからなる複合相を有する磁性薄膜に関する研究が数多く報告されてる。
【０００３】
例えばアメリカ特許５３０２４６９号明細書には、Ｆｅ−Ｍ−Ｏ組成（但しＭはＹ、Ｈｆ、Ｚｒ等）を有し、磁性層の平均結晶粒径が１０００Å以下の軟磁性薄膜が開示されている。
また日本応用磁気学会誌第２０巻、第４６９〜４７２頁には、Ｆｅ−Ｘ−Ｏ（Ｘ＝Ｙ、Ｎｄ、Ｓｍ等）組成の高比抵抗膜が微細な磁性粒子による優れた軟磁気特性とセラミック絶縁相による高電気抵抗とを併せ持つこと、そしてこれらの特性はグラニュラー構造を形成する磁性粒子の組成や粒径および分散状態並びに絶縁相である粒界の厚さにより大きく左右されることが開示されている。
【０００４】
めっき膜としては、特開昭６２−１２０４９７号公報に、粒子径０．０１μｍから１μｍの酸化物微粒子を分散させためっき液から電解により酸化物が金属皮膜中に分散した複合めっき膜を得ることが開示されている。
さらに、めっき法による酸化物膜の形成方法として、特開平４−１７５２２６号公報には、ＬａとＭｎの塩の混合液を電解液とし比較的高電圧で電気分解することでペロブスカイト構造を有するＬａＭｎＯ薄膜が得られることが開示されている。さらに特開平５−３９５８５号公報には、同様の方法でＬａＣｏ０3 薄膜が得られることが開示されている。
また、特開平６−１３２１２８号公報には、めっき法により形成された非晶質軟磁性層と電解酸化法により形成された酸化層とからなる多層膜構造の軟磁性積層膜が開示されている。
さらに、特開平６−１５１１７１号公報には、磁性めっき成膜時に逆電解をかける交流電解法により、一度成膜した膜を再溶解し、多層膜構造を形成し高周波での透磁率を高くすることが開示されている。
【０００５】
従来公知の金属磁性微粒子が高抵抗酸化物相により絶縁された構造を有する軟磁性薄膜は、スパッタ法等の真空成膜法により形成されていた。しかし真空成膜法は設備価格、運転価格が高く、また成膜速度が遅いことから、現実の磁気デバイスに応用して安価に量産することは困難であった。
【０００６】
これに対して、電気化学的手法による成膜であるいわゆるめっき法は大量生産に適した薄膜形成方法である。しかし、めっき法では、所望の構造である金属磁性微粒子が高抵抗酸化物相により絶縁された構造を有する軟磁性薄膜を成膜することが困難であった。
例えば、単に酸化物微粒子を分散させためっき液から電解により酸化物が金属皮膜中に分散された複合めっきにおいては、形成された膜は酸化物微粒子が金属相の海の中に浮かぶという構造であり、その比抵抗は低かった。またこの方法では、酸化物微粒子を製造し、それをめっき液に分散する工程を要した。
【０００７】
これに対して、めっき法により酸化物を形成する手法として、いくつかの方法が知られているが、これらは酸化物膜のみを形成するものであり、金属相と酸化物相との２つの異なる相を同時に形成することは不可能であった。
また、一度作製した金属層を交流電解や電解酸化法に付すことにより、金属層に加えて、その金属層が一部溶解したことにより形成される結晶構造が金属層とは異なる層又は金属酸化層を追加的に有する多層膜は知られていたが、これはあくまで多層膜構造であり、しかも酸化物層又は変質層の主成分はもとの金属であり、その効果は公知のスパッタ法による金属磁性微粒子が高抵抗酸化物相により絶縁させた構造を有する軟磁性薄膜には及ばないものであった。
【０００８】
【発明が解決しようとする課題】
本発明者は、上記課題を解決するために鋭意検討研究した結果、大量生産に適しためっき法を用いて、スパッタ法で成膜された膜と同じ構造を有する高比抵抗軟磁性めっき膜およびその製造方法を完成するに至った。
本発明は量産性が高く、かつ膜の比抵抗が高く、特に高周波での磁気特性が優れためっき膜およびその製造方法を提供することを目的とする。
【０００９】
【課題を解決するための手段】
このような目的は、下記の本発明により達成される。
即ち、本発明は、Ｍ(-) イオン（ここで、Ｍ(-) は水の分解電位よりも卑な析出電位を有する元素から選ばれる１種類以上の元素を表わす）とＭ(+) イオン（ここで、Ｍ(+) は水の分解電位よりも貴な析出電位を有する元素から選ばれる１種類以上の元素を表わす）との両方の元素イオンを含有する水溶液に導電性基体を電極として交流電流を印加して電解を行うことによりＭ(-) の酸化物相とＭ(+) の金属相とを有する複合めっき膜を得ることを特徴とする、めっき膜の製造方法に関する。
Ｍ(+) は、Ｆｅ、Ｃｏ又はＮｉの少なくとも１種であるのが好ましい。
Ｍ(-) は、元素周期律表第３Ａ族元素、第３Ｂ族元素、第４Ａ族元素及び第４Ｂ族元素から選ばれる少なくとも１種の元素であるのが好ましく、Ｔｂ、Ｓｍ、Ｄｙ、Ｎｄ、Ｙ、Ｈｆ、Ｚｒ、Ａｌ及びＳｉから選ばれる少なくとも１種の元素であるのがより一層好ましい。
【００１０】
かかる方法によって得られるめっき膜も新規であり、従って、本発明は、少なくとも
・Ｆｅ、Ｃｏ及びＮｉから選ばれる少なくとも１種を主成分とする金属の相
並びに
・前記金属相を絶縁する、水の分解電位よりも卑な析出電位を有する元素から選ばれる１種類以上の元素Ｍ(-) の酸化物の相
の２つの相を有することを特徴とする複合めっき膜に関するものでもある。
【００１１】
Ｍ(-) は、前述のように、元素周期律表第３Ａ族元素、第３Ｂ族元素、第４Ａ族元素及び第４Ｂ族元素から選ばれる少なくとも１種の元素であるのが好ましく、Ｔｂ、Ｓｍ、Ｄｙ、Ｎｄ、Ｙ、Ｈｆ、Ｚｒ、Ａｌ及びＳｉから選ばれる少なくとも１種の元素であるのがより一層好ましい。
本発明のめっき膜は、Ｆｅ、Ｃｏ及びＮｉから選ばれる少なくとも１種を主成分とする金属相を有する。すなわちＦｅ、Ｃｏ、ＮｉまたはＦｅ−Ｃｏ、Ｆｅ−Ｎｉ、Ｎｉ−Ｆｅ−Ｃｏ等の合金を主成分とする。これらの金属イオンの析出電位は水の分解電位よりも貴なために、水溶液から適当な陽極を用い、陰極上に、これらの金属薄膜を形成することは広く知られている。
【００１２】
析出電位とは、その元素が還元されて陰極に析出が開始される電位を示す。この析出電位は、概ね元素の標準電極電位と極めて深い相関があるため、本発明においては析出電位とは元素の標準電極電位を示す。すなわち、例えば電気化学便覧（電気化学協会編、丸善発行、昭和６０年）の第７１頁には各種の電極反応の水溶液系の標準電極電位で示されている。例えば還元反応の標準電極電位を見ると２価鉄は−０．４４０Ｖ、ニッケルは−０．２３６Ｖ、コバルトは−０．２８７Ｖで、いずれも金属に還元されることがわかる。すなわち本発明においては、析出電位は標準電極電位と等しいと定義するために、鉄、ニッケル、コバルトの析出電位はそれぞれ−０．４４０Ｖ、−０．２３６Ｖ、−０．２８７Ｖと見なすことが可能であり、これらの電位はいずれも水の分解電位−１．２９Ｖよりも貴である。
【００１３】
これに対してアルミニウムの還元反応の標準電極電位は−１．６８Ｖで、水の分解電位−１．２９Ｖよりも卑である。このため水溶液から電析を行っても、陰極では水の分解反応が優先して進行するためにアルミニウムが陰極に析出することはないことがわかる。同様に元素周期律表第３Ａ族元素、第３Ｂ族元素、第４Ａ族元素、第４Ｂ族元素及び第５Ａ族元素の中で、例えばＴｂ、Ｓｍ、Ｄｙ、Ｎｄ、Ｙ、Ｈｆ、Ｚｒ、Ｓｉ等の還元反応の標準電極電位、すなわち析出電位は水の分解電位とほぼ等しいか、それよりも卑であり、同様に水溶液から陰極に金属として成膜することはできない。
【００１４】
本発明者らは、このような水の分解電位よりも卑な析出電位を有する元素から選ばれる１種類以上の元素イオンを含有する水溶液においては、通常のめっきとは逆に、陽極における酸化反応によって水の分解電位よりも卑な析出電位を有する元素の酸化物が陽極上に形成されることを見出した。
例えばテルビニウムイオンを含有するめっき液に、２枚の銅板を電極として電解反応を行うことで、陽極に酸化テルビウムが析出することが確認された。この際、陰極では水素発生が起こる。
【００１５】
そしてさらに、析出電位が水の分解電位よりも卑な元素から選ばれる１種類以上の元素イオンであるＭ(-) イオンと析出電位が水の分解電位よりも貴な元素から選ばれる１種類以上の元素イオンであるＭ(+) イオンとの両方の元素イオンを含有する水溶液に導電性基体を電極として交流電流を印加して電解を行うことによって、金属相と酸化物相との２つの相を有する複合膜を１つのめっき浴から形成できることを見出すに至った。すなわち交流電解法において、成膜すべき基体側が陰極になっている間は、に水の分解電位よりも貴な析出電位を有する元素の金属相が基体上成膜され、逆に基体側が陽極になっている間は、水の分解電位よりも卑な析出電位を有する元素の酸化物相が基体上に成膜される。
各種の元素が酸化物を形成する際の標準生成エンタルピー、即ち生成熱は、その元素の酸化しやすさを示す指標として用いることができる。例えば化学便覧（丸善）によるとＡｌでは１６７５ｋＪ／モル、Ｎｂでは１９００ｋＪ／モル、Ｔｂでは１８６５ｋＪ／モル、Ｙでは１８１５ｋＪ／モルである。これに対してＣｏは２３８ｋＪ／モル、Ｆｅは８２４ｋＪ／モルである、すなわち、析出電位が卑な元素ほど酸化物を形成しやすいことがわかる。このために本方法によって析出電位が貴な元素の金属相と析出電位が卑な元素の酸化物相とを有する複合めっき膜が得られるものと考える。
【００１６】
この結果、水の分解電位よりも貴な析出電位を有する元素Ｍ(+) の金属相、特にＦｅ、Ｃｏ、Ｎｉから選ばれる少なくとも１種を主成分とする金属相と水の分解電位よりも卑な析出電位を有する元素から選ばれる１種類以上の元素Ｍ(-) の酸化物相との少なくとも２つの異なる相を有し、前記金属相が前記酸化物相中に分散されたことを特徴とする複合めっき膜が、１つのめっき浴から容易に成膜可能となった。
本発明の複合めっき膜は、前記の２つの相に加えて前記金属の酸化物の相を含むこともある。本発明のめっき膜は、このような金属酸化物の相を含まないのが好ましいが、含んでいても性能上大きな問題点は生じない。
【００１７】
【発明の実施の形態】
以下、本発明の好適な実施の形態を詳細に説明する。
めっきされる元素イオンは、公知の各種の水溶性塩として供給される。すなわち、硫酸塩、リン酸塩、塩化物塩、酢酸塩等である。なお、特に硝酸塩を用いた場合に高特性の膜が得られる。これは成膜されためっき膜の結晶格子間に侵入型で窒素が含有されているためか、あるいは窒化物が形成されているためと考えられる。
【００１８】
めっき浴中に存在させるＭ(+) イオン及びＭ(-) イオンの浴中イオン濃度比Ｍ(+) ／Ｍ(-) は通常０．１〜１０程度であり、１〜５程度であるのが特に好ましい。
めっき浴中には、Ｍ(+) イオン及びＭ(-) イオンに加えて、クエン酸ナトリウム、ロッシェル塩、ほう酸、塩化アンモニウム、水酸化ナトリウム等の助剤を添加するのが一般的である。
めっき浴温度は常温〜９０℃程度にするのが一般的である。
交流電解周波数は０．００１〜１００Ｈｚ程度にするのが一般的である。
電流密度は１０〜１００００ｍＡ／ｄｍ2 程度にするのが一般的である。
基板及び対極としては、銅、チタン、ステンレスその他の当技術分野においてよく知られているものを用いることができる。
【００１９】
得られる複合めっき膜は、１００μΩｃｍ以上の比抵抗を有するのが好ましく、１５０μΩｃｍ以上の比抵抗を有するのが特に好ましい。前記範囲以上では渦電流損失による１０ＭＨｚ以上での高周波での磁気特性の劣化が小さい。
さらに、磁性金属相を主成分とし、その金属層の平均結晶粒径Ｄが１０００Å以下、特に好ましくは５００Å以下である場合には、優れた軟磁気特性、低保磁力、Ｈｃ＜１０ Ｏｅ、高透磁率、μ＞５００が実現する。
【００２０】
より優れた高比抵抗、軟磁気特性を有するめっき膜を得るための条件は、めっき浴組成、温度、撹拌強度等の成膜条件、基板等により異なるが、特に交流電解条件により管理することができる。すなわち、通常のめっきである成膜する基板が陰極となる時間Ｔｐと基板が陽極となる時間Ｔｎとの比又はＴｐ／（Ｔｐ＋Ｔｎ）であるデューティー比ｄ、Ｔｐの電流密度とＴｎの電流密度との間の比、並びに（Ｔｐ＋Ｔｎ）の切り替え時間である周波数が重要である。
これらを最適化することでスパッタ膜と同じ磁性金属相の粒界に酸化物高比抵抗相が形成された構造の複合相を有する磁性薄膜を得ることができる。
一般にｄは１０〜９０、Ｔｐの電流密度とＴｎの電流密度との間の比は０．１〜５、周波数は０．００１〜１００Ｈｚとするのが好ましい。いずれも前記範囲以外では、どちらかの相が１００％近くになり、所望の特性が得られない。
【００２１】
また、スパッタ法による同様の構造を有する高比抵抗軟磁性膜と同様に、磁場中成膜や磁場中熱処理により異方性を制御することが可能である。所望の方向に強い磁気異方性を誘導することで高異方性磁界膜を得ることができる。このような高異方性磁界膜は特に高周波での特性に優れている。
【００２２】
【実施例】
以下に本発明の実施例を示し、本発明を更に詳細に説明する。
表１に浴組成及び成膜条件を示す。なお、撹拌には窒素ガスバブリングを用い、対向永久磁石の直流磁界中（約３００ Ｏｅ）で成膜を行った。
膜組成分析には蛍光Ｘ線法、ＥＳＣＡを併用し、酸素を除いた金属組成比を求め、結晶粒径はＸ線回折法、比抵抗は４端子法、保磁力はＶＳＭ、透磁率は８の字コイル法を、飽和磁歪は光てこ法を用い評価した。
【００２３】
なお、実施例１では、浴中金属イオン濃度、錯化剤濃度、ｐＨ調整剤濃度、さらにデューティー比ｄを変化させた。図１に実施例１の代表的なＸ線回折パターンを示す。金属鉄のピークと基板である銅のピークしか観察されていないことから酸化鉄は殆ど存在していないことがわかる。テルビウムは含有量が少ないために明瞭なピークは観察されない。すなわち本めっき膜は強磁性体である鉄がほぼ全て金属であり、所望の構造が、実現している可能性が極めて高いことを示差している。さらに、図２に、浴中ロッシェル塩濃度を変化させた場合の膜中のテルビウムの含有量を示す。この条件範囲では５〜１３ａｔ％の範囲で変化していることがわかる。これは従来公知のスパッタ法による膜とほぼ同等の組成が本発明により実現していることを示している。またＥＳＣＡによる化学状態分析により膜中のテルビウムは全て酸化物であることが確認された。また、ＥＳＣＡによる化学状態分析により、膜中のテルビウムは全て酸化物状態であり、鉄は殆どが金属状態（非酸化物）であることが確認された。
【００２４】
それ以外の実施例を含めた膜組成、および特性を表２、表３に示す。
【００２５】
【表１】
【表２】
【表３】
【発明の効果】
以上の説明からわかるように、本発明に従えば、量産性が高く、かつ膜の比抵抗が高く、特に高周波での磁気特性が優れためっき膜およびその製造方法が提供される。
【図面の簡単な説明】
【図１】本発明のめっき膜のＸ線回折ピーク図である。
【図２】本発明のめっき条件において浴中ロッシェル塩濃度を変化させた場合の膜中テルビウム含有量の変化を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic plating film that can be used for various thin film magnetic devices, such as a thin film inductor, a thin film transformer, and the like, and particularly a thin film device used at a high frequency of 10 MHz or more, and a method for manufacturing the same.
[0002]
[Prior art]
In thin film magnetic devices, eddy current loss becomes a major problem as the operating frequency increases. In order to solve this problem, many studies on magnetic thin films having a composite phase composed of a magnetic metal phase such as iron or cobalt and an oxide high resistivity phase have been reported.
[0003]
For example, US Pat. No. 5,302,469 discloses a soft magnetic thin film having a Fe—M—O composition (where M is Y, Hf, Zr, etc.) and an average crystal grain size of the magnetic layer being 1000 μm or less. .
In addition, the Journal of Japan Society for Applied Magnetics, Vol. 20, pages 469-472, Fe-XO (X = Y, Nd, Sm, etc.) high resistivity film has excellent soft magnetic properties due to fine magnetic particles. And high electrical resistance due to the ceramic insulating phase, and these characteristics are greatly influenced by the composition, particle size and dispersion state of the magnetic particles forming the granular structure, and the thickness of the grain boundary which is the insulating phase. It is disclosed.
[0004]
As a plating film, Japanese Patent Application Laid-Open No. Sho 62-120497 obtains a composite plating film in which an oxide is dispersed in a metal film by electrolysis from a plating solution in which oxide fine particles having a particle diameter of 0.01 μm to 1 μm are dispersed. Is disclosed.
Furthermore, as a method for forming an oxide film by plating, JP-A-4-175226 discloses LaMnO having a perovskite structure by electrolysis at a relatively high voltage using a mixed solution of a salt of La and Mn as an electrolytic solution. It is disclosed that a thin film can be obtained. Furthermore, Japanese Patent Laid-Open No. 5-39585 discloses that a LaCoO 3 thin film can be obtained by the same method.
JP-A-6-132128 discloses a soft magnetic multilayer film having a multilayer structure comprising an amorphous soft magnetic layer formed by plating and an oxide layer formed by electrolytic oxidation. .
Furthermore, Japanese Patent Laid-Open No. 6-151171 discloses that a film once formed is re-dissolved by an alternating current electrolysis method in which reverse electrolysis is performed at the time of magnetic plating film formation to form a multilayer film structure and increase the magnetic permeability at high frequency. It is disclosed.
[0005]
A conventionally known soft magnetic thin film having a structure in which metal magnetic fine particles are insulated by a high resistance oxide phase has been formed by a vacuum film forming method such as a sputtering method. However, the vacuum film formation method is expensive in equipment and operation, and has a low film formation speed. Therefore, it is difficult to apply it to an actual magnetic device for mass production at a low cost.
[0006]
On the other hand, a so-called plating method, which is film formation by an electrochemical method, is a thin film formation method suitable for mass production. However, in the plating method, it is difficult to form a soft magnetic thin film having a structure in which metal magnetic fine particles having a desired structure are insulated by a high-resistance oxide phase.
For example, in composite plating in which oxide is dispersed in a metal film by electrolysis from a plating solution in which oxide particles are simply dispersed, the formed film has a structure in which the oxide particles float in the sea of the metal phase. Yes, its specific resistance was low. This method also requires a step of producing oxide fine particles and dispersing them in the plating solution.
[0007]
On the other hand, several methods are known as a method for forming an oxide by plating. However, these methods form only an oxide film, and two methods, a metal phase and an oxide phase. It was impossible to form different phases simultaneously.
In addition to the metal layer, the once formed metal layer is subjected to alternating current electrolysis or electrolytic oxidation, so that the crystal structure formed by partially dissolving the metal layer is different from the metal layer or metal oxide. A multilayer film having additional layers has been known, but this is a multilayer film structure, and the main component of the oxide layer or the altered layer is the original metal, and the effect is obtained by a known sputtering method. This was inferior to a soft magnetic thin film having a structure in which metal magnetic fine particles were insulated by a high resistance oxide phase.
[0008]
[Problems to be solved by the invention]
As a result of diligent study to solve the above problems, the present inventor has used a plating method suitable for mass production, and a high resistivity soft magnetic plating film having the same structure as a film formed by sputtering. The manufacturing method has been completed.
An object of the present invention is to provide a plating film having high mass productivity, high specific resistance of the film, and excellent magnetic characteristics particularly at high frequencies, and a method for producing the same.
[0009]
[Means for Solving the Problems]
Such an object is achieved by the present invention described below.
That is, the present invention relates to M (-) ions (where M (-) represents one or more elements selected from elements having a lower deposition potential than the decomposition potential of water) and M (+) ions. (Where M (+) represents one or more elements selected from elements having a precipitating potential higher than the decomposition potential of water) and an aqueous solution containing both elemental ions as a conductive substrate as an electrode The present invention relates to a method for producing a plating film, characterized in that a composite plating film having an M (−) oxide phase and an M (+) metal phase is obtained by performing electrolysis by applying an alternating current.
M (+) is preferably at least one of Fe, Co, or Ni.
M (−) is preferably at least one element selected from Group 3A elements, Group 3B elements, Group 4A elements, and Group 4B elements of the Periodic Table of Elements. Tb, Sm, Dy, Nd More preferably, it is at least one element selected from Y, Hf, Zr, Al and Si.
[0010]
The plating film obtained by such a method is also novel. Therefore, the present invention provides at least: a metal phase mainly composed of at least one selected from Fe, Co, and Ni; and water that insulates the metal phase. The present invention also relates to a composite plating film characterized by having two phases of an oxide phase of one or more kinds of elements M (−) selected from elements having a lower deposition potential than the decomposition potential.
[0011]
As described above, M (−) is preferably at least one element selected from Group 3A elements, Group 3B elements, Group 4A elements, and Group 4B elements of the Periodic Table of Elements, Tb, It is even more preferable that the element is at least one element selected from Sm, Dy, Nd, Y, Hf, Zr, Al, and Si.
The plated film of the present invention has a metal phase mainly composed of at least one selected from Fe, Co, and Ni. That is, the main component is Fe, Co, Ni, or an alloy such as Fe—Co, Fe—Ni, Ni—Fe—Co. Since the deposition potential of these metal ions is nobler than the decomposition potential of water, it is widely known to form these metal thin films on the cathode using an appropriate anode from an aqueous solution.
[0012]
The deposition potential is a potential at which the element is reduced and deposition starts on the cathode. Since this deposition potential has a very deep correlation with the standard electrode potential of the element, the deposition potential represents the standard electrode potential of the element in the present invention. That is, for example, page 71 of Electrochemical Handbook (edited by Electrochemical Society, published by Maruzen, 1985) shows the standard electrode potentials of various aqueous solutions for electrode reactions. For example, looking at the standard electrode potential of the reduction reaction, it can be seen that divalent iron is -0.440 V, nickel is -0.236 V, and cobalt is -0.287 V, both of which are reduced to metal. That is, in the present invention, since the deposition potential is defined as being equal to the standard electrode potential, the deposition potentials of iron, nickel, and cobalt can be regarded as -0.440V, -0.236V, and -0.287V, respectively. Yes, both of these potentials are nobler than the decomposition potential of water-1.29V.
[0013]
On the other hand, the standard electrode potential for the reduction reaction of aluminum is −1.68 V, which is lower than the decomposition potential of water −1.29 V. For this reason, even when electrodeposition is performed from an aqueous solution, it is understood that aluminum does not deposit on the cathode because the decomposition reaction of water proceeds preferentially at the cathode. Similarly, among the 3A group element, 3B group element, 4A group element, 4B group element and 5A group element of the periodic table, for example, Tb, Sm, Dy, Nd, Y, Hf, Zr, Si The standard electrode potential of the reduction reaction, such as the precipitation potential, is substantially equal to or lower than the decomposition potential of water, and similarly, a metal film cannot be formed from the aqueous solution to the cathode.
[0014]
In the aqueous solution containing one or more element ions selected from elements having a base deposition potential lower than the decomposition potential of water, the present inventors reverse the oxidation reaction at the anode, as opposed to normal plating. Has found that an oxide of an element having a base precipitation potential lower than the decomposition potential of water is formed on the anode.
For example, it was confirmed that terbium oxide was deposited on the anode by performing an electrolytic reaction on a plating solution containing terbium ions using two copper plates as electrodes. At this time, hydrogen generation occurs at the cathode.
[0015]
In addition, M (-) ions, which are one or more element ions selected from elements whose precipitation potential is lower than the decomposition potential of water, and one or more elements selected from elements whose precipitation potential is higher than the decomposition potential of water Two phases, a metal phase and an oxide phase, are obtained by applying an alternating current to an aqueous solution containing both element ions, M (+) ions, which are elemental ions, and using a conductive substrate as an electrode. It came to be found that a composite film having the above can be formed from one plating bath. That is, in the alternating current electrolysis method, while the substrate side to be deposited is the cathode, a metal phase of an element having a deposition potential nobler than the decomposition potential of water is deposited on the substrate, and conversely, the substrate side is the anode. During this time, an oxide phase of an element having a lower precipitation potential than the decomposition potential of water is formed on the substrate.
The standard enthalpy of formation when various elements form oxides, that is, the heat of formation, can be used as an index indicating the ease of oxidation of the element. For example, according to the Chemical Handbook (Maruzen), Al is 1675 kJ / mol, Nb is 1900 kJ / mol, Tb is 1865 kJ / mol, and Y is 1815 kJ / mol. On the other hand, Co is 238 kJ / mol and Fe is 824 kJ / mol, that is, an element having a lower precipitation potential is more likely to form an oxide. For this reason, it is considered that a composite plating film having a metal phase of an element having a noble precipitation potential and an oxide phase of an element having a noble precipitation potential can be obtained by this method.
[0016]
As a result, the metal phase of the element M (+) having a precipitating potential more precious than the decomposition potential of water, especially the metal phase mainly composed of at least one selected from Fe, Co, and Ni, and the decomposition potential of water. It has at least two different phases with an oxide phase of one or more elements M (-) selected from elements having a base precipitation potential, and the metal phase is dispersed in the oxide phase The composite plating film can be easily formed from one plating bath.
The composite plating film of the present invention may contain a phase of the metal oxide in addition to the two phases. Although it is preferable that the plating film of the present invention does not contain such a metal oxide phase, the inclusion of such a metal oxide does not cause a significant problem in performance.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail.
The element ions to be plated are supplied as various known water-soluble salts. That is, sulfates, phosphates, chlorides, acetates, and the like. In particular, a film having high characteristics can be obtained when nitrate is used. This is presumably because nitrogen is contained interstitially between the crystal lattices of the deposited plating film or because nitride is formed.
[0018]
The ion concentration ratio M (+) / M (-) in the bath of M (+) ions and M (-) ions present in the plating bath is usually about 0.1 to 10, and about 1 to 5. Is particularly preferred.
In addition to M (+) ions and M (-) ions, auxiliary agents such as sodium citrate, Rochelle salt, boric acid, ammonium chloride and sodium hydroxide are generally added to the plating bath.
The plating bath temperature is generally from room temperature to about 90 ° C.
The AC electrolysis frequency is generally about 0.001 to 100 Hz.
Current density is common to about 10~10000mA / dm 2.
As the substrate and the counter electrode, those well known in the art such as copper, titanium, stainless steel and the like can be used.
[0019]
The obtained composite plating film preferably has a specific resistance of 100 μΩcm or more, and particularly preferably has a specific resistance of 150 μΩcm or more. Above the above range, the deterioration of magnetic characteristics at high frequencies above 10 MHz due to eddy current loss is small.
Further, when the magnetic metal phase is the main component and the average crystal grain size D of the metal layer is 1000 Å or less, particularly preferably 500 Å or less, excellent soft magnetic properties, low coercive force, Hc <10 Oe, high Permeability, μ> 500 is realized.
[0020]
The conditions for obtaining a plating film having higher specific resistance and soft magnetic properties differ depending on the plating bath composition, film formation conditions such as temperature, stirring strength, etc., the substrate, etc. it can. That is, the ratio of the time Tp when the substrate to be deposited, which is a normal plating, becomes a cathode and the time Tn when the substrate becomes an anode, or the duty ratio d, Tp, and the current density of Tn, which are Tp / (Tp + Tn) The ratio between and the frequency which is the switching time of (Tp + Tn) is important.
By optimizing these, it is possible to obtain a magnetic thin film having a composite phase having a structure in which an oxide high resistivity phase is formed at the same grain boundary of the magnetic metal phase as the sputtered film.
In general, d is preferably 10 to 90, the ratio between the current density of Tp and the current density of Tn is 0.1 to 5, and the frequency is preferably 0.001 to 100 Hz. In either case, outside of the above range, either phase is close to 100%, and desired characteristics cannot be obtained.
[0021]
Further, anisotropy can be controlled by film formation in a magnetic field or heat treatment in a magnetic field, as in the case of a high resistivity soft magnetic film having a similar structure by sputtering. A highly anisotropic magnetic field film can be obtained by inducing strong magnetic anisotropy in a desired direction. Such a highly anisotropic magnetic film is particularly excellent in characteristics at high frequencies.
[0022]
【Example】
Examples of the present invention will be described below to explain the present invention in more detail.
Table 1 shows the bath composition and film forming conditions. Nitrogen gas bubbling was used for stirring, and film formation was performed in a direct current magnetic field (about 300 Oe) of an opposed permanent magnet.
For the film composition analysis, the fluorescent X-ray method and ESCA are used together to obtain the metal composition ratio excluding oxygen. The crystal grain size is the X-ray diffraction method, the specific resistance is the 4-terminal method, the coercive force is VSM, and the magnetic permeability is 8 The S-shaped coil method was used, and saturation magnetostriction was evaluated using the optical lever method.
[0023]
In Example 1, the metal ion concentration in the bath, the complexing agent concentration, the pH adjusting agent concentration, and the duty ratio d were changed. FIG. 1 shows a typical X-ray diffraction pattern of Example 1. Since only the peak of metallic iron and the peak of copper as the substrate are observed, it can be seen that there is almost no iron oxide. Since terbium has a low content, no clear peak is observed. In other words, this plating film shows that iron, which is a ferromagnetic material, is almost entirely metal, and that the desired structure is very likely to be realized. Further, FIG. 2 shows the terbium content in the film when the Rochelle salt concentration in the bath is changed. In this condition range, it can be seen that the change is in the range of 5 to 13 at%. This indicates that the present invention realizes a composition almost equivalent to a film formed by a conventionally known sputtering method. Moreover, it was confirmed by the chemical state analysis by ESCA that all the terbium in the film was an oxide. Further, it was confirmed by chemical state analysis by ESCA that all terbium in the film was in an oxide state, and most of iron was in a metal state (non-oxide).
[0024]
Tables 2 and 3 show film compositions and characteristics including other examples.
[0025]
[Table 1]
[Table 2]
[Table 3]
【The invention's effect】
As can be seen from the above description, according to the present invention, a plated film having high mass productivity, high specific resistance of the film, and excellent magnetic properties particularly at high frequencies, and a method for producing the same are provided.
[Brief description of the drawings]
FIG. 1 is an X-ray diffraction peak diagram of a plating film of the present invention.
FIG. 2 is a graph showing changes in the terbium content in the film when the Rochelle salt concentration in the bath is changed under the plating conditions of the present invention.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32967597A JP3920428B2 (en) | 1997-11-14 | 1997-11-14 | Plating film and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32967597A JP3920428B2 (en) | 1997-11-14 | 1997-11-14 | Plating film and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11150020A JPH11150020A (en) | 1999-06-02 |
| JP3920428B2 true JP3920428B2 (en) | 2007-05-30 |
Family
ID=18224020
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32967597A Expired - Lifetime JP3920428B2 (en) | 1997-11-14 | 1997-11-14 | Plating film and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3920428B2 (en) |
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1997
- 1997-11-14 JP JP32967597A patent/JP3920428B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH11150020A (en) | 1999-06-02 |
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