JP3619021B2

JP3619021B2 - Thin-film magnetic head plating apparatus and thin-film magnetic head

Info

Publication number: JP3619021B2
Application number: JP22327698A
Authority: JP
Inventors: 眞治古市; 清治藤田; 岳夫佐々木
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 1998-08-06
Filing date: 1998-08-06
Publication date: 2005-02-09
Anticipated expiration: 2018-08-06
Also published as: JP2000054198A

Description

【０００１】
【発明の属する技術分野】
本発明は、陰極が着脱可能であって、電気めっきにより均一な膜厚を得る薄膜磁気ヘッド製造用めっき装置と、それを用いて製造された薄膜磁気ヘッドに関するものである。
【０００２】
【従来の技術】
記録再生機能を有する薄膜磁気ヘッドは図１に斜視断面図で示すように、アルミナチタンカーバイドなどで作られた非磁性基板１１の上に、下部シールド１３、磁気抵抗効果素子１４、上部シールドと下部磁極を兼ねた磁性膜１５、上部磁極１６、下部磁極と上部磁極を巻回しするようにコイル４１、４２、磁気抵抗効果素子１４、コイル４１、４２と外部回路とを接続するための端子１７、端子表面膜１８で構成されている。ここで各薄膜を絶縁する絶縁膜の記載は省略している。これらの薄膜は磁性膜や導電性膜であり、スパッタや電気めっきで作製されている。特に下部シールド１３、上部シールドと下部磁極を兼ねた磁性膜１５、上部磁極１６、コイル４１、４２、端子１７、端子表面膜１８は数μｍ以上の膜厚を持つことや、複雑な形状を作る必要があるため電気めっきが主に持ちいられている。
【０００３】
これらの電気めっきは、図２に示すような電気めっき装置が用いられる事が多い。めっき装置のめっき槽２０の底面には、被めっきウェファー（以下陰極と言う）１０にめっき電流を供給する陰極電極２１、めっき膜厚分布を改善する補助陰極２２が配置される。陰極１０は陰極電極２１に陰極を密着させるためと、陰極を着脱するためのシリンダー２３が設けられる。陰極１０はシリンダー２３に真空吸着されるか、機械的に保持、固定される。めっき槽２０には陰極１０と対向する様に陽極２４が配置され、陽極２４と陰極電極２１、また陽極２４と補助陰極２２間にはめっき電流を供給、制御する直流電源２５、２５’が接続される。めっき槽２０にはめっき液２６をめっき槽に導入する導入口２７、めっき液を排出する排出口２８、めっき液の液位を保つ液位板２９、２９’より構成される。ここで、めっき液を撹拌する機構、めっき液の漏洩を防止するパッキン等の図面記載、説明は省略した。
【０００４】
めっきの手順を簡単に説明すると、下降したシリンダー２３に陰極１０を載せシリンダー２３を上昇させ陰極電極２１に密着させる。めっき液導入口２７よりめっき液をめっき槽２０に導入し、液位板２９を乗り越えためっき液は排出口２８より回収される。このめっき液の導入、回収は陰極にめっきを行っている間続けられ常にめっき液は循環されるものである。めっき槽にめっき液が満たされると、直流電源２５、２５’から陽極２４、陰極電極２１を介して陰極１０に、また補助電極２２にめっき電流が給電され、陰極および補助陰極にめっき膜が析出される。所定のめっき膜厚が得られた時点で直流電源２５、２５’からの給電が断たれると同じくして、めっき液の供給も断たれる。めっき液回収バルブ３１を開けめっき液を完全にめっき槽２０内から排出、回収する。シリンダー２３を下降させ陰極１０を取り外し一連のめっき作業が終了する。
【０００５】
陰極に析出させるめっき膜に要求される特性としては膜厚の均一性が上げられる。膜厚の均一性はめっき電流密度の均一性と言うこともできる。特に磁性めっきを行う時めっき電流密度により、めっき膜の組成が変動し磁気特性が変化すると言う問題がある。つまり膜厚の均一性を得ることが磁気特性の均一性を得ることであり、膜厚の均一性を得ることでめっき電流密度の均一性を得ることになる。
【０００６】
補助陰極２２を用いないで陰極にめっきを行うと、陰極の外周部のめっき電流密度が上がり膜厚が厚くなる傾向がある。外周部のめっき電流を補助陰極２２に流し陰極の膜厚分布を改善する方法は、額縁めっき法等の名で従来から用いられている。
【０００７】
図３に補助陰極２２の効果を陰極の径方向の膜厚を示し説明する。陰極の径は直径１５０ｍｍで外周部５ｍｍは陰極電極２１と密着する部分であるので、めっき膜は析出しないもので径方向の膜厚は５ｍｍから１４５ｍｍの範囲で示している。補助陰極の内径は１４０ｍｍ、外径は２００ｍｍである。直流電源２５’、陽極２４、補助陰極２２の経路で流れる電流をｉ’、直流電源２５、陽極２４、陰極１０、陰極電極２１の経路で流れる電流をｉとして、ｉを一定電流値に固定してｉ’を変化させめっきを行った時の陰極の径方向膜厚である。図中ａはｉ’＝０（Ａ）でありｂ，ｃ，ｄ，ｅの順にｉ’を増加してめっきを行っている。ちなみにｉは０．９８（Ａ）でｉ’はａ＝０（Ａ）、ｂ＝０．８２８（Ａ）、ｃ＝１．６５６（Ａ）、ｄ＝１．９６３（Ａ），ｅ＝２．５７２（Ａ）である。
【０００８】
ａは補助電極２２には電流が流れない状態つまり補助電極２２がない状態を表していると言える。ａは陰極外周部の膜厚が中央部に比べ薄く凹形状を示しているが、ｉ’が増加するに従い凹形状から陰極中央部の膜厚が外周部に比べ厚くなる凸形状に変化していることがわかる。つまり凹から凸に変化する点のｉ’を補助電極に流すことにより、陰極の膜厚ばらつきを最少にすることができる。説明したように補助陰極は陰極の膜厚均一化に非常に有効であることがわかる。
【０００９】
【発明が解決しようとする課題】
しかし、ｃが示すように陰極の全域に渡り膜厚が均一ではなく、補助電極に近い陰極外周部は膜厚が薄くなっている。この膜厚が薄い部分を陰極中心部と同じ膜厚にするためｉ’の値を図３のｃの電流値近傍で詳細に検討したが、補助陰極に近い陰極外周部の膜厚を増加させることは出来なかった。薄膜磁気ヘッドとして所望のヘッド特性を得るために必要な膜厚が得られる範囲（以下、有効めっき範囲と言う）は陰極にめっきされる範囲（陰極電極内径に相当する）より小さくならざるを得なかった。
【００１０】
例えば図３のｃでは、陰極中心点の膜厚±０．２μｍを薄膜磁気ヘッドに要求される膜厚とすると、この膜厚が得られる範囲は陰極外端より１９ｍｍから１３１ｍｍの範囲である。つまりφ１１２ｍｍの領域となる。陰極にめっきされる範囲は陰極電極の内径の領域であるのでφ１４０ｍｍの領域である。めっきされる領域と要求されるめっき膜厚が得られる領域の比を有効めっき範囲とすると、図３のｃでは８０（％）となる。つまりめっきを行った面積の２０（％）は膜厚不良で使えないことになる。
【００１１】
図４に陰極と陰極電極、補助陰極の関係を示す。陰極電極は陰極との密着性を上げるため、０．１〜０．３ｍｍと薄いチタンまたは銅のリング状の金属板を使用している。陰極電極２１と補助電極２２を電気的に絶縁するために絶縁材３３が挿入されている。絶縁体３３は陰極電極と補助電極を電気的に絶縁するだけでなく弾力性を持たせ陰極と陰極電極の密着性を上げる役目も合わせ持たせるためめっき液で溶けたり、膨潤しないシリコンゴムが主に用いられている。絶縁材３３の厚みは０．５ｍｍ程度である。
【００１２】
補助陰極２２、絶縁材３３、陰極電極２１の厚さを大きくすると、補助陰極表面と陰極表面との段差が大きくなり、めっき槽２０の底部に深い窪みができるため、めっき液撹拌装置（図示していない）を用いても、陰極表面のめっき液の循環が悪くなるためできうる限り補助陰極２２、絶縁材３３は薄いことが好ましい。補助陰極２２は陰極の膜厚分布を改善するためだけでなく、陰極を陰極電極にシリンダーが押しつける力を受けとめ、陰極と陰極電極の密着性を得て導電およびめっき液の漏洩防止を図る必要がある。このため補助電極材には銅に比べ機械的強度の高いチタン材を用いても２〜３ｍｍ位の厚さにならざるを得ない。
【００１３】
補助陰極の内径は陰極と陰極電極の密着性、めっき液の漏洩を防止するため陰極電極の内径と略同等の寸法にすることが従来から行われていた。陰極は所定のめっき膜厚が得られればめっきは終了し、次の陰極に交換されるが、補助陰極にはめっきが析出するばかりであるため、補助陰極と陰極電極が析出しためっき膜で短絡し、めっき電流ｉ，ｉ’が制御できなくなる現象が起こる。補助電極と陰極電極が短絡しないように定期的に補助陰極に析出しためっき膜を除去する必要があった。
【００１４】
【発明が解決しようとする課題】
そこで、本発明では陰極の有効めっき範囲の拡大と、補助陰極と陰極電極が短絡するまでの時間の延長をすることができる薄膜磁気ヘッド製造用めっき装置を提供することを目的とする。
【００１５】
【問題を解決するための手段】
本発明のめっき装置は、陰極と、前記陰極にめっき電流を供給する陰極電極と、前記陰極のめっき膜厚分布を制御する補助陰極を有し、補助陰極と陰極電極の内径は同等で、補助陰極の露出導電部の内径を陰極電極の内径より大きくすることを特徴とする。この補助陰極は、陰極電極に陰極を密着させる際に生じる力に耐えられる機械的強度を有することが好ましい。露出導電部とは、補助電極の表面において、めっき液との間で電流を導通させる領域を示す。また、上記のめっき装置において、補助陰極の内径と陰極電極の内径は同じで、補助陰極の内径側面と補助陰極内径側上面に絶縁樹脂を塗布するか、若しくは絶縁リングを付加することで、補助陰極の露出導電部内径寸法を陰極電極の内径より大きくすることができる。
【００１６】
また、上記の本発明においては、前記補助陰極は電気絶縁物により露出導電部の内径寸法を大きくすることを特徴とする。この電気絶縁物は、次のような構成として補助陰極に適用できる。例えば、補助陰極の一部分を電気絶縁物に置換した構成、物理または化学的な処理を施して補助陰極の一部分を絶縁物に変換した構成、または補助陰極の一部分を絶縁物で被覆もしくは被着させた構成などとすることができる。
【００１７】
また、本発明において、前記補助陰極の少なくとも内径側面は電気的絶縁がなされ、補助陰極と陰極電極の内径差は２〜１６ｍｍであることが望ましい。このように内径差を選択することにより、有効めっき範囲を９５％以上にすることができる。さらに、補助陰極と陰極電極の内径差を２〜１２ｍｍとすることで、有効めっき範囲内での膜厚分布の広がりを抑制し、均一な膜厚を得ることができる。
【００１８】
また、本発明において、前記補助陰極の一部分に絶縁樹脂を塗布するか、あるいは絶縁リングを付加することによって、補助陰極の露出導電部内径を大きくすることができる。ここでいう一部分としては補助陰極の内径側面が好ましいが、内径側上面あるいは下面を含んでもよい。
【００１９】
また、本発明の薄膜磁気ヘッドは、上記のめっき装置でめっきされることにより、膜厚を均一にすることができる。従って、これらの薄膜磁気ヘッドを形成したウェファーについても、ウェファー上の位置によってめっき膜厚の偏りがなく、薄膜磁気ヘッドの歩留まりを高めることができる。
【００２０】
【発明の実施の形態】
以下図面を参照しながら本発明の実施態様について詳細に説明する。図５は本発明のめっき装置の一実施態様の主要部断面図である。図７、図８は本発明の他の実施態様の主要部断面図である。これらの図面および従来のめっき装置を示す図２、図４で共通の部分は同じ参照符号を用いている。
図５において陰極電極２１、絶縁体３３、補助陰極５２の内径は略同一であり、図中に機械的内径寸法と記載している。補助陰極５２の内径側の側面と上面の一部に絶縁層５３を付加し絶縁層５３で覆われた部分はめっき電流が流れずめっきがされないものである。この絶縁層を除き補助陰極の露出導電部内径を電気的内径寸法として図中に記載している。機械的内径寸法と補助陰極露出導電部内径寸法の差の半値を補助電極に付加された絶縁層幅ｗと規定している。すなわち、内径差は２ｗに相当する。ここで補助電極の内径側側面に付けられた絶縁層の厚みはｗの値には含まれていない。絶縁層は０．１〜０．２ｍｍ厚でテフロン樹脂を焼き付け塗装した。
【００２１】
図６に絶縁層幅ｗと陰極のめっき膜厚の分布を示す。実験に用いためっき膜はＮｉＦｅ合金膜であり、めっき液のＮｉイオンとＦｅイオンの比はＮｉ／Ｆｅ＝４０で、ＰＨは２．８〜２．９である。陰極に流す電流ｉ＝０．９８（Ａ）、補助陰極に流す電流ｉ’＝１．６７（Ａ）と一定にして３５分間めっきを行い陰極１０の中央部で、３．５μｍのめっき膜厚とした。
【００２２】
図６では補助陰極に絶縁層がない従来のめっき装置、補助電極内径側面のみに絶縁層を付加したものと、補助電極内径側面と補助電極上面に絶縁層幅ｗを最大１５ｍｍまで変化させためっき装置の各々について、有効めっき範囲を示している。有効めっき範囲は陰極電極内径である１４０ｍｍの領域を１００％とし、めっき膜厚が３．５±０．２μｍの値が得られる範囲を％で表している。
【００２３】
補助陰極に絶縁層がない従来の方法ではめっき有効範囲は８０％であるが、補助電極内径側面のみ絶縁層を付加することにより９５％までめっき有効範囲は増加する。補助電極内径側面と補助電極上面に絶縁層を付け絶縁層幅ｗ＝１〜８ｍｍの範囲では９７％以上のめっき有効範囲が得られた。更に絶縁層幅ｗを増やしていくとめっき有効範囲は減少しｗ＝１５ｍｍでは７５％と、従来方法に比べても悪化することがわかった。ｗ＝６ｍｍを越えると陰極中央部の膜厚が薄く外周部が厚くなり、補助陰極としての効果が薄れてくることがわかった。絶縁層幅ｗは１〜８ｍｍが良い、好ましくは１〜６ｍｍの範囲である。補助陰極内径側面に絶縁層を付けず、補助陰極上面に絶縁層を設けてもめっき有効範囲は９５％以上は得られなかったことから、補助陰極内径側面の絶縁層はめっき有効範囲拡大に効果があると言える。以上のことから補助陰極内径側面と補助陰極上面の１〜８ｍｍ範囲に絶縁層を設けることはめっき有効範囲の拡大に有効である。
【００２４】
図５において絶縁層５３を被覆することによって補助陰極の露出導電部内径寸法を大きくし、陰極のめっき有効範囲を拡大しても、機械的内径寸法は変わらないためシリンダー２３による陰極の陰極電極への密着状態は何等変わることなく良好な結果が得られた。
【００２５】
補助陰極内径側面と補助陰極上面の１〜８ｍｍ範囲に絶縁層を設けたため、陰極電極との間隔が拡がり補助陰極と陰極電極との短絡の危険性は大幅に減少した。絶縁層を設けない従来方法では累計めっき膜厚が３００μｍ位に達すると補助陰極に析出しためっき膜を除去する必要があった。これは概略ＮｉＦｅめっきで累計５０時間、Ｃｕめっきで累計１０時間で補助陰極に析出しためっき膜を除去することになる。補助陰極に析出しためっき膜は補助陰極形状、面積を変えることになるが陰極のめっき有効範囲に影響しなければ問題ない。補助陰極に析出しためっき膜除去回数は従来にくらべ１／３〜１／５に減少した。
【００２６】
図７、図８に本発明の一実施形態であるめっき装置の主要部の断面図である。補助陰極の絶縁層として絶縁材を塗布するのではなく、補助陰極７１、８１に絶縁リング７２、８２を取り付けたものである。絶縁リングの材質はめっき液で溶解、膨潤しないテフロンを用いたが、セラミックやプラスチックでも良いことは言うまでもない。
【００２７】
【発明の効果】
以上説明したように、本発明の補助陰極を用いることで陰極の有効めっき範囲を拡大でき、陰極と称してきたウェファーからの薄膜磁気ヘッドの取れ数の増加と歩留まりの向上が図れる。また補助陰極導電部と陰極電極の間隔を大きくすることにより、補助陰極と陰極電極間の短絡の危険性を減らし、補助陰極に析出しためっき膜の除去回数を減らすことができる。
【図面の簡単な説明】
【図１】薄膜磁気ヘッドの斜視断面図。
【図２】従来のめっき装置の断面図。
【図３】従来の補助陰極の効果を説明する図。
【図４】従来のめっき装置の断面図。
【図５】本発明のめっき装置の断面図。
【図６】絶縁層幅ｗと陰極のめっき膜厚の分布を説明する図。
【図７】本発明のめっき装置の断面図。
【図８】本発明のめっき装置の断面図。
【符号の説明】
１０陰極電極、１１非磁性基板、１３下部シールド、１４磁気抵抗効果素子、１５磁性膜、１６上部磁極、１７端子、１８端子表面膜、２０めっき槽、２１陰極電極、２２補助陰極、２３シリンダー、２４陽極、２５２５‘ 直流電源、２６めっき液、２７導入口、２８排出口、２９２９’液位板、３１めっき液回収バルブ、３３絶縁体、４１４２コイル、５２補助陰極、５３絶縁層、７１８１補助陰極、７２８２絶縁リング
＆＃２６；[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plating apparatus for manufacturing a thin film magnetic head in which a cathode can be attached and detached and a uniform film thickness is obtained by electroplating, and a thin film magnetic head manufactured using the same.
[0002]
[Prior art]
As shown in the perspective sectional view of FIG. 1, a thin film magnetic head having a recording / reproducing function is formed on a nonmagnetic substrate 11 made of alumina titanium carbide or the like, on a lower shield 13, a magnetoresistive effect element 14, an upper shield and a lower portion. A magnetic film 15 also serving as a magnetic pole, an upper magnetic pole 16, a coil 41, 42, a magnetoresistive effect element 14, a terminal 17 for connecting the coils 41, 42 and an external circuit so as to wind the lower magnetic pole and the upper magnetic pole, The terminal surface film 18 is configured. Here, description of an insulating film for insulating each thin film is omitted. These thin films are magnetic films or conductive films, and are produced by sputtering or electroplating. In particular, the lower shield 13, the magnetic film 15 serving as both the upper shield and the lower magnetic pole, the upper magnetic pole 16, the coils 41 and 42, the terminal 17, and the terminal surface film 18 have a film thickness of several μm or more, or create a complicated shape. Electroplating is mainly used because it is necessary.
[0003]
In these electroplating, an electroplating apparatus as shown in FIG. 2 is often used. On the bottom surface of the plating tank 20 of the plating apparatus, a cathode electrode 21 for supplying a plating current to a wafer to be plated (hereinafter referred to as a cathode) 10 and an auxiliary cathode 22 for improving the plating film thickness distribution are arranged. The cathode 10 is provided with a cylinder 23 for bringing the cathode into close contact with the cathode electrode 21 and for attaching and detaching the cathode. The cathode 10 is vacuum-adsorbed on the cylinder 23 or is mechanically held and fixed. An anode 24 is arranged in the plating tank 20 so as to face the cathode 10, and DC power sources 25 and 25 ′ for supplying and controlling a plating current are connected between the anode 24 and the cathode electrode 21 and between the anode 24 and the auxiliary cathode 22. Is done. The plating tank 20 includes an inlet 27 for introducing the plating solution 26 into the plating tank, a discharge port 28 for discharging the plating solution, and liquid level plates 29 and 29 ′ for maintaining the liquid level of the plating solution. Here, description and description of the drawings such as a mechanism for stirring the plating solution and a packing for preventing leakage of the plating solution are omitted.
[0004]
The plating procedure will be briefly described. The cathode 10 is placed on the lowered cylinder 23, and the cylinder 23 is raised and brought into close contact with the cathode electrode 21. The plating solution is introduced into the plating tank 20 from the plating solution introduction port 27, and the plating solution that has passed over the liquid level plate 29 is collected from the discharge port 28. The introduction and recovery of the plating solution is continued while plating on the cathode, and the plating solution is always circulated. When the plating bath is filled with the plating solution, a plating current is supplied from the DC power sources 25 and 25 'to the cathode 10 via the anode 24 and the cathode electrode 21 and to the auxiliary electrode 22, and a plating film is deposited on the cathode and the auxiliary cathode. Is done. When the power supply from the DC power sources 25 and 25 'is cut off when the predetermined plating film thickness is obtained, the supply of the plating solution is also cut off. The plating solution recovery valve 31 is opened, and the plating solution is completely discharged from the plating tank 20 and recovered. The cylinder 23 is lowered, the cathode 10 is removed, and a series of plating operations is completed.
[0005]
As a characteristic required for the plating film deposited on the cathode, the uniformity of the film thickness can be increased. It can be said that the uniformity of the film thickness is the uniformity of the plating current density. In particular, when performing magnetic plating, there is a problem that the composition of the plating film varies and the magnetic characteristics change depending on the plating current density. In other words, obtaining uniformity in film thickness means obtaining uniformity in magnetic properties, and obtaining uniformity in film thickness results in uniformity in plating current density.
[0006]
If the cathode is plated without using the auxiliary cathode 22, the plating current density at the outer periphery of the cathode tends to increase and the film thickness tends to increase. A method of improving the film thickness distribution of the cathode by flowing the plating current of the outer peripheral portion to the auxiliary cathode 22 has been conventionally used in the name of frame plating.
[0007]
FIG. 3 explains the effect of the auxiliary cathode 22 by showing the film thickness in the radial direction of the cathode. Since the diameter of the cathode is 150 mm and the outer peripheral portion 5 mm is in close contact with the cathode electrode 21, no plating film is deposited, and the thickness in the radial direction is shown in the range of 5 mm to 145 mm. The auxiliary cathode has an inner diameter of 140 mm and an outer diameter of 200 mm. The current flowing through the path of the DC power supply 25 ′, the anode 24, and the auxiliary cathode 22 is i ′, and the current flowing through the path of the DC power supply 25, the anode 24, the cathode 10, and the cathode electrode 21 is i, and i is fixed at a constant current value. The thickness in the radial direction of the cathode when plating is performed with i ′ varied. In the figure, a is i ′ = 0 (A), and plating is performed by increasing i ′ in the order of b, c, d, and e. Incidentally, i is 0.98 (A), and i ′ is a = 0 (A), b = 0.828 (A), c = 1.656 (A), d = 1.963 (A), e = 2. .572 (A).
[0008]
It can be said that a represents a state in which no current flows through the auxiliary electrode 22, that is, a state in which the auxiliary electrode 22 is not present. a shows a concave shape in which the film thickness of the outer peripheral part of the cathode is thinner than that of the central part, but changes from a concave shape to a convex shape in which the film thickness of the central part of the cathode becomes thicker than that of the outer peripheral part as i ′ increases. I understand that. That is, by flowing i ′, which changes from concave to convex, through the auxiliary electrode, the thickness variation of the cathode can be minimized. As explained, the auxiliary cathode is found to be very effective in making the cathode film thickness uniform.
[0009]
[Problems to be solved by the invention]
However, as indicated by c, the film thickness is not uniform over the entire area of the cathode, and the film thickness on the outer peripheral part of the cathode near the auxiliary electrode is thin. In order to make the thin film portion the same film thickness as the cathode central portion, the value of i ′ was examined in detail in the vicinity of the current value of c in FIG. 3, but the film thickness of the cathode outer peripheral portion near the auxiliary cathode is increased. I couldn't. The range in which the film thickness necessary to obtain the desired head characteristics as a thin film magnetic head (hereinafter referred to as the effective plating range) must be smaller than the range in which the cathode is plated (corresponding to the cathode electrode inner diameter). There wasn't.
[0010]
For example, in FIG. 3c, assuming that the film thickness of the cathode central point ± 0.2 μm is the film thickness required for the thin film magnetic head, the film thickness can be obtained from 19 mm to 131 mm from the outer edge of the cathode. That is, it becomes an area of φ112 mm. Since the area to be plated on the cathode is the area of the inner diameter of the cathode electrode, it is an area of φ140 mm. When the ratio of the area to be plated to the area where the required plating film thickness can be obtained is defined as the effective plating range, the ratio is 80 (%) in FIG. That is, 20 (%) of the plated area cannot be used due to film thickness failure.
[0011]
FIG. 4 shows the relationship between the cathode, the cathode electrode, and the auxiliary cathode. The cathode electrode uses a titanium or copper ring-shaped metal plate as thin as 0.1 to 0.3 mm in order to improve adhesion to the cathode. An insulating material 33 is inserted to electrically insulate the cathode electrode 21 from the auxiliary electrode 22. Insulator 33 not only electrically insulates the cathode electrode from the auxiliary electrode, but also has the function of increasing the adhesion between the cathode and the cathode electrode, so that silicon rubber that does not melt or swell is mainly used. It is used for. The thickness of the insulating material 33 is about 0.5 mm.
[0012]
When the thicknesses of the auxiliary cathode 22, the insulating material 33, and the cathode electrode 21 are increased, the step between the auxiliary cathode surface and the cathode surface is increased, and a deep recess is formed at the bottom of the plating tank 20. However, it is preferable that the auxiliary cathode 22 and the insulating material 33 are as thin as possible because the circulation of the plating solution on the cathode surface is deteriorated. The auxiliary cathode 22 needs not only to improve the thickness distribution of the cathode, but also to receive the force that the cylinder presses the cathode against the cathode electrode, to obtain adhesion between the cathode and the cathode electrode, and to prevent leakage of the conductive and plating solution. is there. For this reason, even if a titanium material having higher mechanical strength than copper is used for the auxiliary electrode material, the thickness must be about 2 to 3 mm.
[0013]
Conventionally, the inner diameter of the auxiliary cathode has been approximately the same as the inner diameter of the cathode electrode in order to prevent adhesion between the cathode and the cathode electrode and leakage of the plating solution. When the predetermined plating film thickness is obtained, the plating is completed and replaced with the next cathode. However, since the plating is only deposited on the auxiliary cathode, the auxiliary cathode and the cathode electrode are short-circuited with the deposited film Then, a phenomenon occurs in which the plating currents i and i ′ cannot be controlled. It was necessary to periodically remove the plating film deposited on the auxiliary cathode so as not to short-circuit the auxiliary electrode and the cathode electrode.
[0014]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a plating apparatus for manufacturing a thin film magnetic head capable of extending the effective plating range of the cathode and extending the time until the auxiliary cathode and the cathode electrode are short-circuited.
[0015]
[Means for solving problems]
The plating apparatus of the present invention has a cathode, a cathode electrode for supplying a plating current to the cathode, and an auxiliary cathode for controlling the plating film thickness distribution of the cathode. The inside diameter of the exposed conductive portion of the cathode is made larger than the inside diameter of the cathode electrode. The auxiliary cathode preferably has a mechanical strength that can withstand the force generated when the cathode is brought into close contact with the cathode electrode. The exposed conductive portion refers to a region where current is conducted with the plating solution on the surface of the auxiliary electrode. In the above plating apparatus, the inner diameter of the auxiliary cathode and the inner diameter of the cathode electrode are the same, and an auxiliary resin is applied to the inner diameter side surface of the auxiliary cathode and the upper surface of the auxiliary cathode inner diameter side, or an insulating ring is added, thereby assisting. The inner diameter dimension of the exposed conductive portion of the cathode can be made larger than the inner diameter of the cathode electrode.
[0016]
In the present invention, the auxiliary cathode is characterized in that the inner diameter dimension of the exposed conductive portion is increased by an electrical insulator. This electrical insulator can be applied to the auxiliary cathode in the following configuration. For example, a configuration in which a part of the auxiliary cathode is replaced with an electrical insulator, a configuration in which a part of the auxiliary cathode is converted into an insulator by performing physical or chemical treatment, or a portion of the auxiliary cathode is coated or deposited with an insulator. Or the like.
[0017]
In the present invention, it is preferable that at least the inner diameter side surface of the auxiliary cathode is electrically insulated, and the inner diameter difference between the auxiliary cathode and the cathode electrode is 2 to 16 mm. By selecting the inner diameter difference in this way, the effective plating range can be 95% or more. Furthermore, by setting the inner diameter difference between the auxiliary cathode and the cathode electrode to 2 to 12 mm, it is possible to suppress the spread of the film thickness distribution within the effective plating range and obtain a uniform film thickness.
[0018]
In the present invention, the exposed conductive portion inner diameter of the auxiliary cathode can be increased by applying an insulating resin to a part of the auxiliary cathode or adding an insulating ring. As a part here, the inner diameter side surface of the auxiliary cathode is preferable, but the upper surface or the lower surface on the inner diameter side may be included.
[0019]
Further, the thin film magnetic head of the present invention can be made uniform by plating with the above plating apparatus. Therefore, the wafer on which these thin film magnetic heads are formed also has no uneven plating film thickness depending on the position on the wafer, and the yield of the thin film magnetic head can be increased.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 5 is a cross-sectional view of the main part of one embodiment of the plating apparatus of the present invention. 7 and 8 are cross-sectional views of the main part of another embodiment of the present invention. In these drawings and FIGS. 2 and 4 showing the conventional plating apparatus, the same reference numerals are used for the common parts.
In FIG. 5, the inner diameters of the cathode electrode 21, the insulator 33, and the auxiliary cathode 52 are substantially the same, and are described as mechanical inner diameter dimensions in the drawing. A portion where the insulating layer 53 is added to the inner side surface and a part of the upper surface of the auxiliary cathode 52 and covered with the insulating layer 53 is a portion where plating current does not flow and plating is not performed. Except for this insulating layer, the exposed conductive portion inside diameter of the auxiliary cathode is shown as an electrical inside diameter in the figure. The half value of the difference between the mechanical inner diameter and the auxiliary cathode exposed conductive portion inner diameter is defined as the insulating layer width w added to the auxiliary electrode. That is, the inner diameter difference corresponds to 2w. Here, the thickness of the insulating layer attached to the inner diameter side surface of the auxiliary electrode is not included in the value of w. The insulating layer was 0.1 to 0.2 mm thick and baked and coated with Teflon resin.
[0021]
FIG. 6 shows the distribution of the insulating layer width w and the plating film thickness of the cathode. The plating film used in the experiment is a NiFe alloy film, the ratio of Ni ions to Fe ions in the plating solution is Ni / Fe = 40, and the pH is 2.8 to 2.9. The plating was carried out for 35 minutes at a constant current i = 0.98 (A) flowing through the cathode and the current i ′ = 1.67 (A) flowing through the auxiliary cathode, and a plating film thickness of 3.5 μm was formed at the center of the cathode 10. It was.
[0022]
In FIG. 6, a conventional plating apparatus having no insulating layer on the auxiliary cathode, an insulating layer added only to the inner side surface of the auxiliary electrode, and plating with the insulating layer width w varied up to 15 mm on the auxiliary electrode inner side surface and the auxiliary electrode upper surface. The effective plating range is shown for each of the devices. The effective plating range is represented by 100% in the area of 140 mm, which is the inner diameter of the cathode electrode, and in%, the range in which the plating film thickness is 3.5 ± 0.2 μm can be obtained.
[0023]
In the conventional method in which the auxiliary cathode has no insulating layer, the plating effective range is 80%. However, the plating effective range is increased to 95% by adding the insulating layer only to the inner side surface of the auxiliary electrode. An insulating layer was attached to the inner surface of the auxiliary electrode and the upper surface of the auxiliary electrode, and an effective plating range of 97% or more was obtained in the range of the insulating layer width w = 1 to 8 mm. Further, it was found that as the insulating layer width w is increased, the effective plating range is reduced, and 75% at w = 15 mm, which is worse than the conventional method. It was found that when w = 6 mm was exceeded, the thickness of the cathode central portion was thin and the outer peripheral portion was thick, and the effect as an auxiliary cathode was diminished. The insulating layer width w is preferably 1 to 8 mm, preferably 1 to 6 mm. Even if an insulating layer was not provided on the inner side surface of the auxiliary cathode and an insulating layer was provided on the upper surface of the auxiliary cathode, the effective plating range could not be over 95%, so the insulating layer on the inner side surface of the auxiliary cathode was effective in expanding the effective plating range. It can be said that there is. From the above, providing an insulating layer in the range of 1 to 8 mm between the auxiliary cathode inner diameter side surface and the auxiliary cathode upper surface is effective in expanding the plating effective range.
[0024]
In FIG. 5, even if the inner diameter dimension of the exposed conductive portion of the auxiliary cathode is increased by covering the insulating layer 53 and the effective plating range of the cathode is expanded, the mechanical inner diameter dimension does not change. Good results were obtained without any change in the contact state.
[0025]
Since the insulating layer was provided in the range of 1 to 8 mm between the inner side surface of the auxiliary cathode and the upper surface of the auxiliary cathode, the distance between the cathode electrode was widened and the risk of short circuit between the auxiliary cathode and the cathode electrode was greatly reduced. In the conventional method in which an insulating layer is not provided, when the cumulative plating film thickness reaches about 300 μm, it is necessary to remove the plating film deposited on the auxiliary cathode. This removes the plating film deposited on the auxiliary cathode in approximately 50 hours by NiFe plating and in 10 hours by Cu plating. The plating film deposited on the auxiliary cathode changes the shape and area of the auxiliary cathode, but there is no problem as long as it does not affect the effective plating range of the cathode. The number of times of removal of the plating film deposited on the auxiliary cathode was reduced to 1/3 to 1/5 compared with the conventional method.
[0026]
7 and 8 are cross-sectional views of the main part of the plating apparatus according to one embodiment of the present invention. Insulating rings 72 and 82 are attached to the auxiliary cathodes 71 and 81 instead of applying an insulating material as an insulating layer of the auxiliary cathode. The insulating ring is made of Teflon which does not dissolve or swell in the plating solution, but it goes without saying that it may be ceramic or plastic.
[0027]
【The invention's effect】
As described above, by using the auxiliary cathode of the present invention, the effective plating range of the cathode can be expanded, and the number of thin film magnetic heads taken from the wafer called the cathode can be increased and the yield can be improved. Further, by increasing the distance between the auxiliary cathode conductive portion and the cathode electrode, it is possible to reduce the risk of a short circuit between the auxiliary cathode and the cathode electrode and reduce the number of times of removal of the plating film deposited on the auxiliary cathode.
[Brief description of the drawings]
FIG. 1 is a perspective sectional view of a thin film magnetic head.
FIG. 2 is a cross-sectional view of a conventional plating apparatus.
FIG. 3 is a diagram for explaining the effect of a conventional auxiliary cathode.
FIG. 4 is a cross-sectional view of a conventional plating apparatus.
FIG. 5 is a sectional view of the plating apparatus of the present invention.
FIG. 6 is a diagram for explaining the distribution of the insulating layer width w and the plating film thickness of the cathode.
FIG. 7 is a cross-sectional view of the plating apparatus of the present invention.
FIG. 8 is a cross-sectional view of the plating apparatus of the present invention.
[Explanation of symbols]
10 Cathode electrode, 11 Nonmagnetic substrate, 13 Lower shield, 14 Magnetoresistive element, 15 Magnetic film, 16 Upper magnetic pole, 17 Terminal, 18 Terminal surface film, 20 Plating tank, 21 Cathode electrode, 22 Auxiliary cathode, 23 Cylinder, 24 anode, 25 25 ′ DC power supply, 26 plating solution, 27 inlet, 28 outlet, 29 29 ′ liquid level plate, 31 plating solution recovery valve, 33 insulator, 41 42 coil, 52 auxiliary cathode, 53 insulating layer, 71 81 auxiliary cathode, 72 82 insulating ring 

Claims

陰極と、前記陰極にめっき電流を供給する陰極電極と、前記陰極のめっき膜厚分布を制御する補助陰極を有するめっき装置に於いて、補助陰極と陰極電極の内径は同等で、補助陰極の露出導電部の内径を陰極電極の内径より大きくすることを特徴とする薄膜磁気ヘッド製造用めっき装置。In a plating apparatus having a cathode, a cathode electrode for supplying a plating current to the cathode, and an auxiliary cathode for controlling the plating film thickness distribution of the cathode, the inner diameters of the auxiliary cathode and the cathode electrode are equal, and the auxiliary cathode is exposed. A plating apparatus for manufacturing a thin film magnetic head, wherein the inner diameter of the conductive portion is larger than the inner diameter of the cathode electrode.

前記補助陰極は電気絶縁物により露出導電部の内径寸法を大きくすることを特徴とする請求項１記載の薄膜磁気ヘッド製造用めっき装置。2. The plating apparatus for manufacturing a thin film magnetic head according to claim 1, wherein the auxiliary cathode has an inner diameter dimension of an exposed conductive portion increased by an electric insulator.

前記補助陰極の少なくとも内径側面は電気的絶縁がなされ、補助陰極と陰極電極の内径差は２〜１６ｍｍであることを特徴とする請求項１または２に記載の薄膜磁気ヘッド製造用めっき装置。The plating apparatus for manufacturing a thin film magnetic head according to claim 1 or 2, wherein at least an inner diameter side surface of the auxiliary cathode is electrically insulated, and an inner diameter difference between the auxiliary cathode and the cathode electrode is 2 to 16 mm.

前記補助陰極の少なくとも内径側面は電気的絶縁がなされ、補助陰極と陰極電極の内径差は２〜１２ｍｍであることを特徴とする請求項１ないし３のいずれかに記載の薄膜磁気ヘッド製造用めっき装置。4. The plating for manufacturing a thin-film magnetic head according to claim 1, wherein at least an inner diameter side surface of the auxiliary cathode is electrically insulated, and an inner diameter difference between the auxiliary cathode and the cathode electrode is 2 to 12 mm. apparatus.

前記補助陰極に絶縁樹脂を塗布するか、あるいは絶縁リングを付加することによって、補助陰極の露出導電部内径を大きくしたことを特徴とする請求項１ないし４のいずれかに記載の薄膜磁気ヘッド製造用めっき装置。5. The thin film magnetic head manufacturing method according to claim 1, wherein the inner diameter of the exposed conductive portion of the auxiliary cathode is increased by applying an insulating resin to the auxiliary cathode or by adding an insulating ring. Plating equipment.

請求項１〜５のいずれかに記載の薄膜磁気ヘッド製造用めっき装置でめっきされたことを特徴とする薄膜磁気ヘッド。A thin film magnetic head, which is plated by the plating apparatus for manufacturing a thin film magnetic head according to claim 1.