JP4623404B2 - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Description

これらは、有機溶剤に溶解あるいは分散可能であり、塗布操作に適した任意の固形分濃度（したがって粘度）の溶液あるいは分散液を容易に調製することができる。好ましい濃度としては約１０〜６０質量％、より好ましい濃度としては約１５〜４０質量％である。また、好ましい粘度としては約５０〜３０，０００ｃＰ、より好ましい粘度としては約５００〜１５，０００ｃＰである。低濃度、低粘度側では、マスキング線がにじみ、高濃度、高粘度側では糸引き等が起こり線幅が不安定になる。
マスキング材溶液によって形成されるマスキング層は、マスキング材溶液の塗布後、必要に応じて乾燥、加熱、光照射などの処理を行なってもよい。
ポリイミド溶液の具体例としては、塗布後の加熱処理により硬化する低分子ポリイミドを２−メトキシエチルエーテルやトリエチレングリコールジメチルエーテルなどの吸湿性の少ない溶剤に溶した溶液（例えば、宇部興産（株）から「ユピコート^ＴＭＦＳ−１００Ｌ」として販売されている。）、あるいは前記式（５）で示されるポリイミド樹脂をＮＭＰ（Ｎ−メチル−２−ピロリドン）やＤＭＡｃ（ジメチルアセトアミド）に溶解した溶液（例えば、新日本理化（株）から「リカコート^ＴＭ」として販売されている。）が好ましく使用できる。
前者は、塗布後１６０〜１８０℃の加熱処理により熱変性し高分子化して硬化し、柔軟性を有し、高い耐熱性と絶縁性を示す膜を与える。このポリイミド膜は、引っ張り強度２．０ｋｇ／ｍｍ^２、硬化膜の伸び率が６５％、初期弾性率４０．６ｋｇ／ｍｍ^２で、ゴム状の性質を保持し熱分解温度４６１℃の高い耐熱性を有している。体積抵抗は加湿下でも１０^１６Ω・ｃｍと高く、誘電率は３．２と低く、絶縁塗膜として優れた電気特性を保持している。
また、後者は２００℃以下の温度で溶剤を除去するだけで、優れた耐熱性、機械特性、電気特性、及び耐薬品性を有する膜を与える。この膜は引っ張り強度約１１．８ｋｇ／ｍｍ^２、硬化膜の伸び率が１４．２％、初期弾性率が２７４ｋｇ／ｍｍ^２以上、５％質量減少温度５１５℃の耐熱性を有し、体積抵抗は１０^１６Ω・ｃｍ、誘電率は３．１（２５℃）、２．８（２００℃）であり優れた電気特性を保持している。
本発明では、上記マスキング材溶液に消泡剤（低級アルコール系、鉱物油系、シリコーン樹脂系、オレイン酸、ポリプロピレングリコールなど）、チキソトロピー付与剤（シリカ微粉末、マイカ、タルク、炭酸カルシウムなど）、樹脂改質用シリコン剤（シランカップリング剤、シリコーンオイル、シリコン系界面活性剤、シリコーン系合成潤滑油など）などを添加することができる。例えばシリコーンオイル（ポリシロキサン）、シランカップリング剤を添加することにより、消泡性（硬化時の発泡を抑える）、離型性（導電性重合体の付着防止）、潤滑姓（細孔部内への浸透性）、電気絶縁姓（漏れ電流防止）、撥水性（導電性重合体の重合時に溶液の侵入（液上がり）防止）、制動・防振性（コンデンサ素子の積層時の圧力に対向）、樹脂の耐熱性・耐候性（架橋機構の導入）の改善が期待できる。
また、本発明では、可溶性ポリイミドシロキサンとエポキシ樹脂からなる組成物（特開平８−２５３６７７号公報（米国特許第５６４３９８６号））を用いることによって、上記シリコーンオイル（ポリシロキサン）の添加と同様の効果を得ることができる。
［マスキング材の塗布方法］
本発明に係る固体電解コンデンサ用基板（以下、単に基板という。）にマスキング材を塗布する装置について、一実施例の概要を示す平面図（図５Ａ）および側面図（図５Ｂ）を参照しながら説明する。
図５の装置は、円盤状の回転ロール（１３）を１回転させる間に、ロール塗布面へのマスキング材を含む溶液の供給、基板へのマスキング材の塗布、およびロール表面に残留するマスキング材の清掃の１サイクルを実施できるように構成されている。
図中、１１は複数の固体電解コンデンサ用基板（１２ａ，１２ｂ，１２ｃ……）の一端を短冊状に固定する金属製ガイドである。
金属製ガイド（１１）への基板の固定は電気的あるいは機械的に接合することにより行なうことができる。接合方法としては、例えば半田付け、導電ペーストによる接合、超音波溶接、スポット溶接、電子ビーム溶接などが挙げられる。
金属製ガイド（１１）は回転ロール（１３）上を矢印方向に直線運動する。金属製ガイド（１１）を移動する手段（図示せず）としてモーター、ベルト、シリンダー等慣用の手段が利用できる。金属製ガイドの進行速度（Ｖ１）と回転ロールの回転速度（Ｖ２）の関係を調整することにより基板（１２）の側面をも塗布することができる。すなわち、図６Ａに示すように、金属製ガイドの進行速度（Ｖ１）が回転速度（Ｖ２）より大きい時は、基板の進行方向先端部の側面を塗布でき、金属製ガイドの進行速度（Ｖ１）が回転速度（Ｖ２）より小さいときは、基板の進行方向後端部の側面部を塗布できる（図６Ｂ）。
また、本発明の装置では、金属ガイドと回転ロールとの相対的な位置関係を反転させ金属ガイドに固定した基板の両面および両側面を塗布できる機構を設けている。
このような機構の一例は金属ガイドの反転機構である。反転はモーター、シリンダーを利用するか、あるいは金属製ガイドの保持部を長手方向に対して回動自在に設け保持部を半回転させることなどにより行なうことができる。
反転した金属ガイドに固定された基板の反対面を塗布するためには、回転ロールの塗布面と基板の塗布位置との関係を調整する必要があるが、慣用の手段により金属ガイドを移動するか、回転ロールの位置を移動するか、あるいは両者を移動することにより行なうことができる。
また、２台の回転ロールを用意し、反転した金属ガイドに固定された基板の未塗布面を専用の回転ロールにて塗布してもよい。
さらに、基板を挟み配置に２台の回転ロールを設置し、金属製ガイドに固定した基板の両面及び両側面を同時にマスキングすることもできる。
回転ロール（１３）は、前記基板の所望の箇所に所定の押圧力で接触する平滑な塗布面を有する円盤状の回転ロールである。
回転ロール（１３）としては、マスキング材を含む溶液に耐性のある硬質の材料からなる金属製（ステンレス鋼等）あるいはセラミック材料製のものが使用される。その大きさは、１回転する間（マスキング材の塗布の１サイクル）にマスキング材が変質しない大きさであればよく、通常直径約２ｍｍ〜約５００ｍｍであり、本発明においては限定されない。また、ロールの塗布面幅は、所望幅にマスキング材が塗布できる幅であり、好ましくは、０．２〜３．０ｍｍ程度である。
前記回転ロール（１３）の周囲には、前記基板との接触位置の後方（回転方向の後方）に塗布面にマスキング材を含む溶液を供給する手段（１４）、基板（１２）との接触位置の前方に回転ロールの塗布面を清掃するスクレーパー（１５）及び拭き取り材（１６）が配設されている。
マスキング材を含む溶液を供給する手段（１４）は、本例では脈動の少ない密閉された定量連続吐出ディスペンサを備えた定量塗布液供給機である。定量塗布液供給機から、マスキング材を含む溶液に耐性のある樹脂製のチューブを通して吐出ニードルにより所定量連続的にロール塗布面にマスキング材を含む溶液を供給する。
また、マスキング材を含む溶液をロール（１３）の塗布面に安定して供給するためにニードル先端部とロール面との距離を安定させる微調整機構が設けられている。このような機構の一例は、マイクロメータヘッド（ネジ機構）を使って上下の位置を微調整するものである。
マスキング材を含む溶液を供給された回転ロール（１３）の塗布面は、基板との接触位置にて一定の押圧力で基板と接触する。この接触時の押圧力は、基板の弾性限度内であり、好ましくは回転運動をするロールの平滑な頂点（塗布面）における撓み量が約０．０３〜０．３ｍｍの範囲となるようにする。具体的な押圧力は、基板の種類や厚みによって異なるため一概に言えないが、例えば０．００２〜０．０２ｇ／基板（幅３ｍｍ×厚さ０．１ｍｍ）程度とする。
次いで、ロール塗布面を清掃する。清掃手段としては、例えば、機械式スクレーパ（１５）と拭き取り材（１６）を使用する。
スクレーパー（１５）はステンレス鋼、セラミックス材料などのロールと同質あるいはそれよりは柔らかい材質からなる材料製（樹脂、鋼材等）のブレードであり、少なくとも先端がロールの塗布面と密接するように配置され、基板塗布後のロールの塗布面に残留するマスキング材をかき落とす。スクレーパー（１５）の前方（回転方向の前方）に配設された、樹脂繊維に有機溶剤及び／または水（マスキング材溶液に使用しているのと同一の溶剤など）をしみ込ませた拭き取り材（１６）にてロール塗布面の付着物をこすり落とし、次の塗布サイクルに備えられる。
本装置ではマスキング材を含む溶液を密閉容器から無脈動式の駆動方式を採用することにより回転ロールの塗布面に安定して供給できる。
［固体電解質］
本発明において、固体電解質としては、ピロール、チオフェン、フランあるいはアニリン構造のいずれか１つの二価基、またはそれらの置換誘導体の少なくとも１つを繰り返し単位として有する導電性重合体が好ましく使用できるが、材料として従来知られているものを特に制限なく使用できる。
例えば、３，４−エチレンジオキシチオフェンモノマー及び酸化剤を好ましくは溶液の形態において、前後して別々にまたは一緒に金属箔の酸化皮膜層に塗布して形成する方法（特開平２−１５６１１号公報（米国特許第４，９１０，６４５号）や特開平１０−３２１４５号公報（欧州特許公開第８２００７６（Ａ２）号））等が利用できる。
一般に導電性重合体には、アリールスルホン酸塩系ドーパントが使用される。例えば、ベンゼンスルホン酸、トルエンスルホン酸、ナフタレンスルホン酸、アントラセンスルホン酸、アントラキノンスルホン酸などの塩を用いることができる。
発明を実施するための最良の形態
以下に実施例を挙げて説明するが、下記の例によって本発明は何ら限定されるものではない。
実施例１：
マスキング工程
厚み１００μｍの化成アルミ箔を３ｍｍ幅に切断（スリット）したものを１３ｍｍずつの長さに切り取り、この箔片の一方の短辺部を金属製ガイドに溶接により固定し、固定していない端から７ｍｍの箇所に粘度８００ｃＰに調整したポリイミド樹脂溶液（宇部興産（株）製；ユピコートＦＳ−１００Ｌ）を、塗布面幅０．４ｍｍの円盤状の塗布装置に供給して、塗布装置の塗布面をアルミ化成箔の全周に当接・押圧して０．８ｍｍ幅に線状に描き、約１８０℃で乾燥させマスキング層（ポリイミド膜）を形成した。
化成処理工程
塗布装置から外した金属製ガイドに固定されたアルミ箔の先端からマスキング線までの部分をアジピン酸アンモニウム水溶液中に浸して１３Ｖの電圧を印加して切口部の未化成部を化成し、誘電体皮膜を形成した。
固体電解質形成工程
化成処理層領域に以下のようにして固体電解質を形成した。
すなわち、アルミ箔の先端から４ｍｍのマスキング層を境にしてマスキング層と逆側の部分（３ｍｍ×４ｍｍ）を３，４−エチレンジオキシチオフェン２０質量％を含むイソプロパノール溶液（溶液１）に浸漬し、引き上げて２５℃で５分間放置した。次にモノマー溶液処理したアルミ箔部分を過硫酸アンモニウム３０質量％を含む水溶液（溶液２）に浸漬し、これを６０℃で１０分間乾燥し、酸化重合を行なった。溶液１に浸漬してから溶液２に浸漬し酸化重合を行なう操作を２５回繰返して固体電解質層を形成した。
チップ型固体電解コンデンサ素子の構築と試験
マスキング層を含む部分をリードフレーム上に銀ペーストで接合しながら３枚重ね、導電性重合体のついていない部分に陽極リード端子を溶接により接続し、全体をエポキシ樹脂で封止し、１２０℃で定格電圧を印加して２時間エージングして合計３０個のチップ型固体電解コンデンサを作製した。作製したチップ型固体電解コンデンサの断面図を図７に示す。
このコンデンサ素子について、２３０℃の温度領域を３０秒通過させることによりリフロー試験を行ない、定格電圧印加後１分後の漏れ電流を測定し、測定値が１ＣＶ以下のものについて平均値を求め、０．０４ＣＶ以上を不良品とした。これらの結果を表１に示す。
コンデンサマスキング部分の構造分析
実施例１の固体電解質形成工程にて金属材料としてアルミニウム箔を使用し、固体電解質として含硫黄高分子（３，４−エチレンジオキシチオフェンの重合体）層による固体電解質層の形成されたコンデンサ材料（試料）をエポキシ樹脂（商品名：Ｑｕｅｔｏｌ−８１２）中に入れ、３０〜６０℃、２０〜３０時間熱硬化させて試料を固定した後、図１ＤのＡ−Ａ′に相当する箇所で切断したマスキング部分周辺の写真（倍率５００倍）を図８に示す。
切断はＡ−Ａ′についてミクロトームで行ない、その切断面について微小体積（１μｍ^３程度）に含まれる元素の組成を分析する装置である電子線マイクロアナライザー（ＥＰＭＡ：ｅｌｃｔｒｏｎ ｐｒｏｂｅ ｍｉｃｒｏａｎａｌｙｓｅｒ）を使用して特定の元素の二次元的な分布状態をマッピング法で観察した。上記の電子線マイクロアナライザーによれば単位体積１μｍ^３に対して、１〜数％（質量）までの元素の定量分析が可能である。
拡大写真中に、アルミニウム芯金（１ａ）、誘電体層（１ｂ）、固体電解質（含硫黄高分子層）（４）及びマスキング層（２）が観察できる。
（１ａ）及び（１ｂ）にはアルミニウム元素が含まれ、（４）には硫黄元素が含まれ、（４）及び（２）には炭素元素が含まれている。従って、炭素、硫黄、アルミニウム等の元素分析を調べることにより、（１ａ）、（１ｂ）、（４）、（２）の各部位について、マスキング材及び重合体の分布が明確になった。その様子を図２に模式図として示す。
硫黄元素（Ｓ）の検出分布の観察から、誘電体層（１ｂ）において固体電解質（４）が分布している領域が明確に別れ、マスキング材が固体電解質の浸入をブロックしていることが判明した。ここで浸入をブロックするとは、マスキング材の浸透部に固体電解質材料が５質量％以上存在しないことをいう。この値は、例えば前記電子線マイクロアナライザーによる識別用元素の検出限界値および固体電解質中の識別用元素の含有率より求めることが出来る。
以上の結果から、本発明による固体電解コンデンサによりコンデンサ素子を形成した場合、漏れ電流、容量などが改善されたコンデンサ特性が得られるのは、マスキング材が誘電体皮膜中に浸透しかつ前記浸透部の上に形成されるが、固体電解質は前記マスキング材の浸透した誘電体皮膜中に浸透できずかつ前記浸透部の上に形成されたマスキング材により完全にブロックされる構造によるものと考えられる。
実施例２：
実施例１においてマスキング材としてポリイミド樹脂溶液（新日本理化（株）製；リカコート^ＴＭ）を用いて塗布したほかは、同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表１に示す。
実施例３：
実施例１において固体電解質形成工程での溶液２に、さらに２−アントラキノンスルホン酸ナトリウム（東京化成社製）が０．０７質量％となるように調製した水溶液で浸漬し、酸化重合を行なったほかは、同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表１に示す。
実施例４：
実施例１において固体電解質形成工程での溶液２に、さらに２−ナフタレンスルホン酸ナトリウム（東京化成社製）が０．０６質量％となるように調製した水溶液で浸漬し、酸化重合を行なったほかは、同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表１に示す。
実施例５：
実施例３において、３，４−エチレンジオキシチオフェンの代わりにＮ−メチルピロールを用いた以外は実施例３と同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表１に示す。
比較例１：
実施例１においてマスキング層を形成する代わりに耐熱性基材と耐熱性粘着剤よりなるテープをアルミ箔の表裏に幅１ｍｍで、張り付けたほかは、同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表１に示す。また、実施例１と同様に、ＥＰＭＡによる硫黄元素の分析から、誘電体層（１ｂ）において、固体電解質層（４）が分布している領域が明確に分かれておらず、マスキング層に固体電解質が浸入していた。
比較例２：
実施例１において高分子絶縁化膜を形成する代わりにフェノール樹脂を塗布硬化させ箔の表裏に幅０．８ｍｍの線を描いたほかは、同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表１に示す。また、比較例１と同様にＥＰＭＡ分析から、マスキング層に固体電解質が浸入していた。

実施例６：
第一マスキング工程
厚み１００μｍの化成アルミ箔を３ｍｍ幅に切断（スリット）したものを１３ｍｍずつの長さに切り取り、この箔片の一方の短辺部を金属製ガイドに溶接により固定し、固定していない端から７ｍｍの箇所に粘度８００ｃｐに調整したポリイミド樹脂溶液（新日本理化（株）製；リカコート^ＴＭ）を、塗布面幅０．４ｍｍの円盤状の塗布装置に供給して、塗布装置の塗布面をアルミ化成箔の全周に当接・押圧して０．８ｍｍ幅に線状に描き、約１８０℃で乾燥させ第一のマスキング層（ポリイミド膜）を形成した。
化成処理工程
塗布装置から外した金属製ガイドに固定されたアルミ箔の先端から第１のマスキング線までの部分をアジピン酸アンモニウム水溶液中に浸して１３Ｖの電圧を印加して切口部の未化成部を化成し、誘電体皮膜を形成した。
第二マスキング工程
次に金属製ガイドに固定されたアルミ箔を再び塗布装置に装着して、固定していない先端から４ｍｍの箇所に上記と同様にしてポリイミド樹脂溶液（新日本理化（株）製；リカコート^ＴＭ）を０．８ｍｍ幅に線状に描き、約１８０℃で乾燥させ第二のマスキング層（ポリイミド膜）を形成した。
固体電解質形成工程
前記第一のマスキング層と第二のマスキング層との間を除く化成処理層領域に以下のようにして固体電解質を形成した。
すなわち、アルミ箔の先端から４ｍｍの第二のマスキング層を境にして第一のマスキング層と逆側の部分（３ｍｍ×４ｍｍ）を３，４−エチレンジオキシチオフェン２０質量％を含むイソプロパノール溶液（溶液１）に浸漬し、引き上げて２５℃で５分間放置した。次にモノマー溶液処理したアルミ箔部分を過硫酸アンモニウム水溶液３０質量％を含む水溶液（溶液２）に浸漬し、これを６０℃で１０分間乾燥し、酸化重合を行なった。溶液１に浸漬してから溶液２に浸漬し酸化重合を行なう操作を２５回繰返して固体電解質層を形成した。
切断工程
上記の固体電解質層を形成したアルミ箔素子の導電性重合体層を形成した部分にカーボンペーストと銀ペーストを付けた後、前記第一のマスキング層と第二のマスキング層との間でアルミ箔を切断した。
チップ型固体電解コンデンサ素子の構築と試験
第二のマスキング層を含む切断部分をリードフレーム上に銀ペーストで接合しながら３枚重ね、導電性重合体のついていない部分に陽極リード端子を溶接により接続し、全体をエポキシ樹脂で封止し、１２０℃で定格電圧を印加して２時間エージングして合計３０個のチップ型固体電解コンデンサを作製した。作製したチップ型固体電解コンデンサの断面図を図７に示す。
このコンデンサ素子について、２３０℃の温度領域を３０秒通過させることによりリフロー試験を行ない、定格電圧印加後１分後の漏れ電流を測定し、測定値が１ＣＶ以下のものについて平均値を求め、０．０４ＣＶ以上を不良品とした。これらの結果を表２に示す。
実施例７：
実施例６において第一マスキング材としてポリイミド樹脂溶液（宇部興産（株）製；ユピコートＦＳ−１００Ｌ）を用いて塗布したほかは、同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表２に示す。
実施例８：
実施例６において第一マスキング材及び第二マスキング材としてポリイミド樹脂溶液（宇部興産（株）製；ユピコート^ＴＭＦＳ−１００Ｌ）を用いて塗布したほかは、同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表２に示す。
実施例９：
実施例８において固体電解質形成工程での溶液２に、さらに２−アントラキノンスルホン酸ナトリウム（東京化成社製）が０．０７質量％となるように調製した水溶液で浸漬し、酸化重合を行なったほかは、同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表２に示す。
実施例１０：
実施例８において固体電解質形成工程での溶液２に、さらに２−ナフタレンスルホン酸ナトリウム（東京化成社製）が０．０６質量％となるように調製した水溶液で浸漬し、酸化重合を行なったほかは、同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表２に示す。
比較例３：
マスキングを一度行なった他は実施例６と同様にしてチップ型固体電解コンデンサを作製した。すなわち、第２のマスキング工程（アルミ箔の先端から４ｍｍの位置）のみを実施して高分子（ポリイミド）膜を形成し、次いで化成処理工程、固体電解質形成工程、及び切断工程を行ない、チップ型固体電解コンデンサを作製し、漏れ電流の測定とリフロー試験を行なった。その結果を表２に示す。
比較例４：
比較例３において第二のマスキング層を形成する代わりに耐熱性基材と耐熱性粘着剤よりなるテープをアルミ箔の表裏に幅１ｍｍで、張り付けたほかは、同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表２に示す。
比較例５：
比較例３において高分子絶縁化膜を形成する代わりにフェノール樹脂を塗布硬化させ箔の表裏に幅０．８ｍｍの線を描いたほかは、同様にしてチップ型固体電解コンデンサを作製し、同様に漏れ電流の測定とリフロー試験を行なった。その結果を表２に示す。

産業上の利用可能性
本発明に係る固体電解コンデンサの製造方法の従来技術に比べた長所は以下の通りである。
（ａ）マスキング材として、従来のテープやエポキシ系、フェノール系樹脂に代えて、ポリイミド樹脂を使用したことにより、誘電体皮膜の表面が十分に被覆され、さらに芯金までの誘電体皮膜中に十分にマスキング材が浸透する構造となる結果、導電性高分子含浸部と陽極部が完全に分離され、漏れ電流が低減し、コンデンサ素子形成時及び素子化した後、リフロー処理時等に発生する応力を緩和することができる。
（ｂ）化成箔切口部を完全に化成することにより、導電性重合体や導電ペーストの切口部への浸入による漏れ電流の増加が防止できる。
（ｃ）マスキング層により、次工程の化成処理の際に化成液がマスキング層を超えて滲み上がることがなく確実にかつ容易に化成処理出来る。またマスキング材が前記誘電体皮膜中に浸透して、かつ前記浸透部の上に形成されるため固体電解質が前記マスキング材が浸透した誘電体皮膜中に浸透できず、前記浸透部の上に形成されたマスキング材によりマスキングされた構造を有するため、陰極部と陽極部とが確実に絶縁できる。
（ｄ）マスキング材として使用するポリイミド膜は導電性重合体の重合時に使用する水系またはアルコール等の有機溶媒に耐性があり誘電体皮膜中に浸透し、陽極部と陰極部との絶縁性を確実に保持できる。
また、マスキングを２回実施する方法によれば、第一のマスキング層（仮マスキング層）により、次工程の化成処理の際に化成液がマスキング層を超えて滲み上がることがなく、必要な箇所（固体電解コンデンサの陽極部を除く箇所）を確実にかつ容易に化成処理出来る。すなわち、仮マスキング層がないと化成液が基板上を滲み上り、化成時の漏れ電流が大きくなり電極と短絡することがある。長い基板（金属箔）を用いて化成液と電極位置の間隔をとれば短絡の可能性は低減できるが、経済性や生産性が低下する。仮マスキング層を設けない場合、化成液の滲み上がり量を規制するのが困難であり、化成状態を管理できないが、マスキングを２回実施する方法によればこのような問題が解決できる。
さらに、本発明のマスキング材塗布方法及び装置によれば、固体電解コンデンサ用のマスキング材を基板に塗布するに際して、ロールを１回転させる毎に溶剤に均一に溶解または分散したマスキング材（ポリイミド樹脂等）を直線状で、かつ安定した線幅で連続的に塗布することができる。
【図面の簡単な説明】
図１Ａ〜図１Ｄは、本発明の固体電解コンデンサの製造工程の概要図である。
図２は、本発明の方法で得られる固体電解コンデンサのマスキング層の構造を顕す模式図である。
図３は、固体電解コンデンサ素子例の断面図である。
図４Ａ〜図４Ｆは、二段マスキング処理を行なう場合の本発明の固体電解コンデンサの製造工程の概要図である。
図５は、マスキング材の塗布を行なう装置例の概要を示す平面図（図５Ａ）及び側面図（図５Ｂ）である。
図６は、基板の側面塗布の説明図である。
図７は、実施例で作成した固体電解コンデンサ素子の断面図である。
図８は、マスキング材を塗布したコンデンサのマスキング部分周辺の断面を示す拡大写真である。Related applications
This application is filed in accordance with the provisions of 35 USC 111 (b), provisional application 60 / 135,843 and provisional application 60 / 135,844 filed May 24, 1999. Is an application based on Article 111 (a) claiming in accordance with the provisions of Article 119 (e) (1).
Technical field
The present invention relates to a solid electrolytic capacitor and a method for manufacturing the same. More specifically, when a solid electrolyte layer is formed on a valve action metal substrate having a dielectric film, the metal substrate portion (anode portion) where the solid electrolyte layer is not provided and the solid electrolyte layer or further a conductive paste or the like thereon The present invention relates to a solid electrolytic capacitor having a masking structure that can reliably insulate a conductor layer (cathode portion) formed by the above method, a manufacturing method thereof, and a method and apparatus for applying a masking material to a substrate of the solid electrolytic capacitor.
Background art
A solid electrolytic capacitor using a conductive polymer is formed by forming a dielectric oxide film on the surface of a valve metal such as aluminum, tantalum, and titanium that has been etched in advance, and forming the conductive polymer on the dielectric oxide film. A solid electrolyte, having a basic structure in which an anode lead wire is connected to an anode terminal of a valve metal (a metal surface portion without a solid electrolyte), and a cathode lead wire is connected to a conductor layer containing a conductive polymer; The whole is sealed with an insulating resin such as an epoxy resin.
Such a solid electrolytic capacitor using a conductive polymer as a solid electrolyte can reduce the equivalent series resistance and leakage current compared to a solid electrolytic capacitor using manganese dioxide or the like as a solid electrolyte, thereby improving the performance and size of electronic equipment. It is useful as a capacitor that can cope with the manufacturing process, and many manufacturing methods have been proposed.
In order to produce a high-performance solid electrolytic capacitor using a conductive polymer, the anode part serving as the anode terminal and the cathode part formed of the conductive layer containing the conductive polymer must be electrically insulated reliably. Is essential.
As a masking means for insulating the anode part and the cathode part of the solid electrolytic capacitor, for example, a method of preventing conduction by applying epoxy, phenol resin, etc. to an unformed part, printing or potting, and curing it (JP-A-3-95910) Publication), a solution containing a polyamic acid salt is electrodeposited on at least a part of a portion of the valve metal that does not form a solid electrolyte to form a polyamic acid film, and then dehydrated and cured by heating to form a polyimide film. A method (Japanese Patent Laid-Open No. 5-47611), a method of forming a tape or a resin-coated film portion made of polypropylene, polyester, silicon resin or fluorine-based resin to prevent the solid electrolyte from creeping up (Japanese Patent Laid-Open No. 5-166681) Gazette), the boundary table between the portion of the metal substrate serving as the anode terminal and the portion where the capacitor is formed Insulating After the resin layer was formed, a method of exposing the metal substrate and removing the insulating resin layer in a portion other than the capacitor (JP-A-9-36003) has been proposed.
In the method using a phenol resin or an epoxy resin as a masking material (Japanese Patent Laid-Open No. 3-95910), the elastic modulus of the resin is high and the stress against the strain is high, so that the damage is great when the capacitor element receives an external force.
The method of forming a polyimide film by the electrodeposition method (Japanese Patent Laid-Open No. 5-47611) can form a film up to the pores as compared with a normal coating method, but the production cost is high because an electrodeposition process is required. In addition, a high temperature dehydration process is required to form a polyimide film.
In order to prevent the solid electrolyte from creeping up during production, a method using an insulating resin tape or a coated film (Japanese Patent Laid-Open No. 5-166681) is to securely attach the end of the substrate with a tape (film). There is a risk that the solid polymer electrolyte may enter the anode side.
In addition, the method of removing the insulating resin layer other than the capacitor and exposing the metal substrate after forming the insulating resin layer (Japanese Patent Laid-Open No. 9-36003) is essentially removing the once formed insulating resin layer. Costly process is required.
As described above, none of the conventional masking means is sufficiently satisfactory, and it is not clear what the masking form (structure) can reliably insulate the anode part and the cathode part of the solid electrolytic capacitor. Is the actual situation.
Object of the invention
An object of the present invention is to provide a solid electrolytic capacitor manufacturing method in which a solid electrolyte layer is formed on a valve-acting metal substrate having a dielectric film, and a metal substrate portion (anode portion) not provided with a solid electrolyte layer and a solid electrolyte layer An object of the present invention is to provide a solid electrolytic capacitor having a masking structure that can reliably insulate a conductive layer (cathode portion) provided with a conductive paste or the like thereon and a method for manufacturing the same.
Furthermore, the subject of this invention is providing the masking material application | coating method and its apparatus which can perform efficiently the masking which can insulate reliably the anode part and cathode part of a solid electrolytic capacitor.
Summary of the Invention
The present inventors (1) As a material for forming a masking material (hereinafter referred to as a masking material coating solution), for example, a solution containing a heat-resistant resin or a precursor thereof or a good insulating property and heat resistance after solidification. Using a solution of low molecular weight polyimide or its precursor, (2) In the conventional metal conversion material foil, the cut portion that occurs when cutting to a desired dimension becomes unformed, causing an increase in leakage current, (3) Conductive heavy metal containing at least one divalent group of pyrrole, thiophene, aniline, furan, or a substituted derivative thereof as a repeating unit as a solid electrolyte. We intensively studied matters such as adopting coalescence. As a result, the present inventors have found that a masking structure in which the masking material is sufficiently adhered onto the dielectric film and sufficiently penetrates through the dielectric film to the core metal can be formed.
In addition, the present inventors have examined the problem that the chemical conversion liquid oozes on the substrate during chemical conversion treatment, and the leakage current during chemical conversion increases to cause a short circuit with the electrode. As a result, the masking step is divided into two steps, and after the temporary masking (first masking layer) is performed before the chemical conversion treatment, the chemical conversion treatment is performed based on the position of the temporary masking, and then the masking (first masking) By applying the second masking layer), the chemical conversion solution does not bleed beyond the temporary masking layer during the chemical conversion treatment, and the necessary part (the part other than the anode part of the solid electrolytic capacitor) can be formed reliably and easily. It was confirmed that it could be processed.
Further, the present inventors masked a heat-resistant resin such as polyimide having good insulating properties and heat resistance on a desired portion (entire circumference) of the valve action etched metal substrate having a metal oxide layer on the surface by a coating method. The method of applying to the substrate as a material was examined.
First
(1) A method in which the masking material is thinly applied in a string shape, for example, by directly applying the masking material to the surface of the substrate (aluminum conversion foil) with a dispenser or the like,
(2) A method of applying to the surface of the aluminum conversion foil with a thin stick such as a brush or bamboo skewer,
(3) A method for screen-printing a masking material on aluminum formed foil was studied.
In the methods (1) and (2), coating can be performed in a short time by partial solidification of bamboo skewers or the like, but work in a long time is difficult and lacks stability. Further, the surface of a typical porous aluminum conversion foil has a property of repelling a masking material, and it is difficult to apply it on a straight line and easily becomes uneven. Moreover, although it is possible to apply | coat uniformly on the surface by the screen printing method of (3), it can apply | coat to predetermined | prescribed thickness (about 10-30 micrometers / single side | surface) and chemical conversion foil side application reliably. Have difficulty.
As described above, in any of the methods, it is difficult to apply the masking material to the entire circumference of the substrate in a uniform line shape.
Next, in order to efficiently apply the masking material to a large number of substrates (aluminum conversion foil), the present inventors attach a plurality of substrates to a guide plate in a strip shape, Considering a promising method of applying a masking material to a metal guide plate moving device with a fixed substrate, a disc-shaped rotating roll having a circumferential surface as a coating surface, a masking material tank in which a part of the rotating roll is immersed, and a roll A scraper that cleans the deposits remaining on the metal guide plate was provided, and an apparatus for applying the masking material by making contact with the circumferential surface of the masking material on the lower surface of the aluminum conversion foil attached to the metal guide plate was examined and examined.
However, in the prototype device, since the solution containing the masking material is applied in an open system (exposed to air), the masking material solidifies in the vicinity of the scraper, and the viscosity of the masking material in the tank changes. However, it has been found that there are problems to be improved, such as the need to change the solution containing the masking material in a short time.
Therefore, (1) fixing one end of a plurality of chemical conversion foils (substrates) in a strip shape on a table (metal guide) that performs linear motion,
(2) Arrangement so that the smooth top surface (application surface) of the disk-shaped roll that rotates is in contact with the back surface (lower side) of the substrate fixed to the metal guide with a constant force;
(3) Supply the masking material to the application surface of the roll by storing the solution containing the masking material in a sealed container and using a quantitative application liquid feeder such as a quantitative continuous discharge dispenser with little pulsation. In a closed system,
(4) A roll coated with a solution containing a masking material uniformly on the circumference of the coated surface is pressed against the chemical conversion foil, and the running speed of the metal plate guide and the rotational speed of the rotary roll are adjusted to adjust Applying masking material to the bottom and side surfaces;
(5) Provide a means for removing and cleaning the masking material remaining on the coated surface of the roll after the roll coated with the solution containing the masking material contacts the chemical conversion foil substrate and before a new coating solution is applied. thing,
As a result, the masking material was successfully applied to the entire circumference of the desired portion of the substrate in a uniform line shape.
That is, this invention provides the manufacturing method of the following solid electrolytic capacitors, the solid electrolytic capacitor obtained by the method, the coating method of a masking material solution, and a coating device.
[1] In a method of manufacturing a solid electrolytic capacitor having a dielectric film and forming a solid electrolyte at a desired position on a metal material having a valve action, the dielectric film penetrates into the dielectric film and A method for producing a solid electrolytic capacitor comprising a step of applying a masking material solution for forming a masking layer thereon.
[2] In a method of manufacturing a solid electrolytic capacitor having a dielectric film and forming a solid electrolyte at a desired position on a metal material having a valve action, the dielectric film penetrates into the dielectric film and Solid electrolysis which has a step of applying a masking material solution for forming a masking layer thereon, and the masking resin which has penetrated into the dielectric film and solidified in the coating step prevents the solid electrolyte formed in the subsequent step from entering. Capacitor manufacturing method.
[3] The method for producing a solid electrolytic capacitor according to [2], wherein the concentration of the solid electrolyte in the masking resin permeation portion of the dielectric film by the masking material solution coating step is equal to or lower than a detection limit value by an electron beam microanalyzer.
[4] A plurality of substrates for a solid electrolytic capacitor are fixed to one end of a metal guide in a strip shape, and a disk-shaped rotating roll is applied to a desired portion of the substrate with a predetermined pressing force while moving the metal guide. The masking layer is formed by applying the masking material solution supplied to the rotating roll coating surface from the masking material solution supplying means to both sides and both sides of the desired portion of the substrate for a solid electrolytic capacitor. 3] The manufacturing method of the solid electrolytic capacitor in any one of.
[5] Manufacture of a solid electrolytic capacitor according to [4], wherein the relative positional relationship between the metal guide and the rotating roll is reversed and the masking material solution is applied to both sides and both sides of the substrate fixed to the metal guide. Method.
[6] In a method of manufacturing a solid electrolytic capacitor having a dielectric film and forming a solid electrolyte at a desired position on a metal material cut into a predetermined shape and having a valve action, masking on the metal material A step of forming a first masking layer by applying a material solution and a step of forming a second masking layer, and penetrating into the dielectric film by at least the second masking layer forming step and the penetrating portion The method for producing a solid electrolytic capacitor according to [1], wherein a masking layer is formed on the substrate.
[7] In a method of manufacturing a solid electrolytic capacitor having a dielectric film and forming a solid electrolyte at a desired position on a metal material having a valve action cut into a predetermined shape,
A step of forming a first masking layer by linearly applying a masking material solution to the entire circumference of the boundary region where the chemical conversion treatment is performed on the metal material, and heating.
Chemical conversion treatment of a region for forming a solid electrolyte separated by a region having the first masking layer of the metal material,
A step of forming a second masking layer by applying a masking material solution in a linear manner to the entire circumference of the region on the metal material subjected to the chemical conversion treatment at a predetermined interval from the first masking layer;
A step of forming a solid electrolyte in a region excluding a space between the first masking layer and the second masking layer in the chemical conversion treatment region; and
The method for producing a solid electrolytic capacitor according to [6], including a step of cutting the metal material in a region between the first masking layer and the second masking layer.
[8] The method for producing a solid electrolytic capacitor according to any one of [1] to [7], wherein a solution of a heat resistant resin or a precursor thereof is used as the masking material solution.
[9] The method for producing a solid electrolytic capacitor according to [8], wherein the solution of the heat resistant resin or a precursor thereof is a low molecular weight polyimide solution or a polyamic acid solution that is solidified by heating.
[10] The method for producing a solid electrolytic capacitor according to [8] or [9], wherein the masking material solution further contains silicone oil, a silane coupling agent, or polyimidesiloxane.
[11] The production of the solid electrolytic capacitor according to any one of [1] to [7], wherein the metal material having a valve action is a material selected from aluminum, tantalum, niobium, titanium, zirconium, and alloys thereof. Method.
[12] The above [1] to [1], wherein the solid electrolyte is a polymer solid electrolyte containing at least one of divalent groups of pyrrole, thiophene, aniline, and furan, or a substituted derivative thereof as a repeating unit. [7] The method for producing a solid electrolytic capacitor according to any one of [7].
[13] The method for producing a solid electrolytic capacitor according to [12], wherein the polymer solid electrolyte includes a polymer of 3,4-ethylenedioxythiophene.
[14] The method for producing a solid electrolytic capacitor according to [12] or [13], wherein the solid electrolyte further contains an aryl sulfonate dopant.
[15] In a solid electrolytic capacitor having a dielectric film and having a solid electrolyte formed at a desired position on a metal material having a valve action, a masking material solution penetrates into the dielectric film and A solid electrolytic capacitor having a structure in which a masking layer is formed thereon and the solid electrolyte does not penetrate into the dielectric film infiltrated with the masking material solution and is masked by the masking layer formed on the infiltrating portion.
[16] The solid electrolytic capacitor according to [15], wherein the masking layer is formed using a masking material solution of a heat resistant resin or a precursor thereof.
[17] The solid electrolytic capacitor according to [15], wherein the concentration of the solid electrolyte in the dielectric film permeated with the masking material solution is equal to or lower than a detection limit value by an electron beam microanalyzer.
[18] A plurality of solid electrolytic capacitor substrates are fixed to one end of a metal guide in a strip shape, and a disk-shaped rotating roll is applied to a desired portion of the substrate with a predetermined pressing force while moving the metal guide. A masking material application method, comprising: contacting a masking material solution supplied from a masking material solution supply means to a rotary roll application surface on both sides and both sides of a desired portion of the substrate for a solid electrolytic capacitor.
[19] The masking material application method according to [18], wherein the masking material solution is applied to both sides and both sides of the substrate fixed to the metal guide by reversing the relative positional relationship between the metal guide and the rotating roll.
[20] A metal guide (11) for fixing one end of a plurality of solid electrolytic capacitor substrates (12) in a strip shape, a means for moving the metal guide, and a predetermined press on a desired location on the substrate (12). A disk-shaped rotating roll (13) that is brought into contact with pressure, means (14) for supplying a solution containing a masking material to the application surface of the rotating roll, and a scraper (15) for cleaning the application surface of the rotating roll (13). A masking material coating apparatus for coating a masking material on both sides and both sides of a desired portion of the solid electrolytic capacitor substrate (12).
[21] The masking material coating apparatus according to [20], wherein the relative positional relationship between the metal guide and the rotating roll is reversed to coat both sides and both sides of the substrate fixed to the metal guide.
[22] The apparatus according to [20], which includes two rotating rolls and applies the opposite surface of the substrate fixed to the inverted metal guide with a dedicated rotating roll.
[23] The masking material coating apparatus according to [20], wherein two rotating rolls arranged so as to sandwich the substrate are provided, and the masking material is simultaneously coated on both sides and both sides of the substrate fixed to the moving metal guide. .
[24] The masking material coating apparatus according to any one of [20] to [23], wherein the substrate is made of a valve action metal material, and the coating surface of the rotating roll contacts the substrate with a pressing force within the elastic limit.
[25] The masking material coating apparatus according to any one of [20] to [23], wherein the rotating roll is a steel material or a ceramic material.
[26] The masking material coating apparatus according to any one of [20] to [25], wherein the scraper is a resin blade that makes line contact with the rotating roll coating surface or a steel blade that is softer than the rotating roll material.
[27] The masking material coating apparatus according to any one of [20] to [26], wherein a wiping material (16) in which an organic solvent and / or water is impregnated into a resin fiber is disposed in front of a scraper.
[28] The masking material application device according to any one of [20] to [27], wherein the masking material supply means (4) is configured by a constant-quantity continuous discharge machine and a tubular member.
An outline of the manufacturing process of the solid electrolytic capacitor of the present invention is shown in FIGS. 1A to 1D, and a schematic view showing the structure of the masking layer of the obtained solid electrolytic capacitor is shown in FIG.
FIG. 1A is a plan view of a metal material (1) having a porous oxide film (dielectric film) serving as a base of a solid electrolytic capacitor, cut to a predetermined size, and FIG. 1B is provided with a masking layer (2). FIG. 1C is a plan view of a state in which a chemical conversion treatment layer (3) has been produced in order to reliably form a porous oxide film at the cut portion that accompanies cutting, and FIG. 1D forms a solid electrolyte layer (4). FIG.
FIG. 2 is a schematic diagram showing an enlarged structure around the masking portion of the AA ′ cut surface in FIG. 1D. As shown in FIG. 2, in the present invention, the masking layer (2) penetrates into the dielectric film (1b) and is formed on the infiltrated part, and the solid penetrates into the dielectric film (1b). The electrolyte does not penetrate into the dielectric film (1b) infiltrated with the masking material and has a structure that is completely masked by a masking layer formed on the infiltrating portion.
As shown in the cross-sectional view of FIG. 3, the actual solid electrolytic capacitor element (9) has a lead wire (6) joined to the anode terminal (5) of the cut surface, and is electrically conductive on the solid electrolyte layer (4) or further thereon. A lead wire (7) is bonded to a cathode on which a conductor layer (not shown) such as a paste is formed, and the whole is sealed with an insulating resin (8) such as an epoxy resin.
When the masking process is performed twice, the solid electrolytic capacitor can be manufactured according to the processes shown in FIGS. 4A to 4F.
FIG. 4A is a plan view of a metal material (1) having a porous oxide film serving as a base of a solid electrolytic capacitor, cut to a predetermined size, and FIG. 4B is a plan view in a state where a first masking layer (2a) is applied. FIG. 4C is a plan view of a state in which a chemical conversion treatment layer (3) has been produced in order to reliably form a porous oxide film at the cut portion accompanying cutting, and FIG. 4D is a state in which a second masking layer (2b) has been applied. FIG. 4E is a plan view of a state in which a solid electrolyte (4) is formed, and FIG. 4F is a solid electrolysis obtained by cutting between the first masking layer (2a) and the second masking layer (2b). It is a top view of a capacitor | condenser element (9).
Detailed Description of the Invention
The present invention will be described in detail below.
[Valve action metal]
The base material of the solid electrolytic capacitor is a valve metal having a dielectric oxide film on the surface. The valve metal is selected from aluminum, tantalum, niobium, titanium, zirconium, or an alloy-based metal foil, rod, or sintered body containing these as a main component. These metals have a dielectric oxide film whose surface is oxidized by oxygen in the air, but are roughened by an etching process or the like by a known method in advance. Next, it is preferable to form a dielectric oxide film reliably by chemical conversion according to a conventional method. As the valve action metal, an aluminum foil having an alumina oxide layer is preferably used.
It is preferable to use a valve action metal that has been roughened and cut in advance to a size that matches the shape of the solid electrolytic capacitor.
As the metal foil having a valve action, the thickness varies depending on the purpose of use, but generally a foil having a thickness of about 40 to 150 μm is used. Moreover, although the size and shape of the metal foil having a valve action vary depending on the application, a rectangular element having a width of about 1 to 50 mm and a length of about 1 to 50 mm is preferable as a flat element unit, and more preferably a width of about 2 to 2. It is 20 mm, length is about 2-20 mm, more preferably width is about 2-5 mm, and length is about 2-6 mm.
[Chemical conversion treatment]
The chemical conversion treatment of the valve action metal cut into a predetermined shape can be performed by various methods. By performing the chemical conversion treatment in advance, even if a defect occurs in the masking layer, an increase in leakage current is prevented.
The conditions for the chemical conversion treatment are not particularly limited. For example, an electrolytic solution containing at least one of oxalic acid, adipic acid, boric acid, phosphoric acid and the like is used, and the electrolytic solution concentration is 0.05% by mass to 20%. Mass%, temperature is 0 ° C. to 90 ° C., current density is 0.1 mA / cm²~ 200mA / cm²The voltage is formed according to the numerical value corresponding to the formation voltage of the coating film already formed on the conversion foil to be processed and the formation time within 60 minutes. More preferably, the electrolytic solution concentration is 0.1 mass% to 15 mass%, the temperature is 20 ° C to 70 ° C, and the current density is 1 mA / cm.²~ 100mA / cm²The conditions are selected within a range of 30 minutes or less.
The conditions of the chemical conversion treatment are suitable as an industrial method, but unless the dielectric oxide film already formed on the surface of the valve metal material is destroyed or deteriorated, the type of electrolyte, concentration of electrolyte, temperature Various conditions such as current density and formation time can be arbitrarily selected.
Before and after the chemical conversion treatment, for example, a phosphoric acid immersion treatment for improving water resistance, a heat treatment for strengthening the film, or an immersion treatment in boiling water can be performed. [Masking material]
The masking layer is provided in order to prevent the chemical conversion liquid from spreading into the portion that becomes the anode of the solid electrolytic capacitor during the chemical conversion treatment, and to ensure insulation from the solid electrolyte (cathode portion) formed in a later step. It is what
As a masking material, a general heat resistant resin, preferably a heat resistant resin which can be dissolved or swelled in a solvent or a precursor thereof, a composition comprising inorganic fine powder and a cellulose resin (Japanese Patent Laid-Open No. 11-80596), etc. Can be used but is not limited to materials. Specific examples include polyphenylsulfone (PPS), polyethersulfone (PES), cyanate ester resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, etc.), low molecular weight polyimides and their Derivatives and the like. Particularly preferred are low molecular weight polyimides, polyethersulfones, fluororesins and their precursors.
When the masking process is performed twice, the first masking layer is provided to prevent the chemical conversion liquid from spreading to the solid electrolytic capacitor anode portion during the chemical conversion treatment. Therefore, the first masking material is not particularly limited, and the general heat resistant resin described above can be used. As the second masking layer, the same material as the first masking material can be used, but in particular, it has sufficient adhesion and filling properties to the valve action metal and can withstand heat treatment up to about 450 ° C. A polyimide excellent in the thickness is preferable.
As polyimide, there is conventionally used a solution in which a precursor polyamic acid is dissolved in a solvent, and after coating, heat treatment is performed at a high temperature to imidize, but heat treatment at 250 to 350 ° C. is required, and anode foil There was a problem such as damage to the dielectric layer on the surface of the substrate due to heat.
In the present invention, curing is sufficiently possible by heat treatment at a low temperature of 200 ° C. or less, preferably 100 to 200 ° C., and there is little external impact such as damage or destruction due to heat of the dielectric layer on the surface of the anode foil. Use polyimide.
Polyimide is a compound containing an imide structure in the main chain. In the present invention, the polyimide represented by the following formulas (1) to (4) having a flexible structure in which intramolecular rotation easily occurs in the skeleton of the diamine component, and 3 Polyimide represented by the following formula (5) obtained by polycondensation reaction of 3,3 ', 4,4'-diphenylsulfonetetracarboxylic dianhydride and aromatic diamines can be preferably used. The average molecular weight is preferably about 1,000 to 1,000,000, more preferably about 2,000 to 200,000.

These can be dissolved or dispersed in an organic solvent, and a solution or dispersion having an arbitrary solid content concentration (and therefore viscosity) suitable for coating operation can be easily prepared. A preferable concentration is about 10 to 60% by mass, and a more preferable concentration is about 15 to 40% by mass. The preferred viscosity is about 50 to 30,000 cP, and the more preferred viscosity is about 500 to 15,000 cP. On the low concentration and low viscosity side, the masking line is blurred, and on the high concentration and high viscosity side, stringing occurs and the line width becomes unstable.
The masking layer formed by the masking material solution may be subjected to treatments such as drying, heating, and light irradiation as necessary after application of the masking material solution.
As a specific example of the polyimide solution, a solution (for example, from Ube Industries, Ltd.) in which a low molecular weight polyimide that is cured by heat treatment after coating is dissolved in a solvent having low hygroscopicity such as 2-methoxyethyl ether or triethylene glycol dimethyl ether. "Iupicoat^TMFS-100L ". ), Or a solution in which the polyimide resin represented by the above formula (5) is dissolved in NMP (N-methyl-2-pyrrolidone) or DMAc (dimethylacetamide) (for example, “Rika Coat” from Shin Nippon Rika Co., Ltd.)^TMIs sold as. ) Can be preferably used.
The former is heat-denatured by application of heat treatment at 160 to 180 ° C. after application, is polymerized and cured, and gives a film having flexibility and high heat resistance and insulation. This polyimide film has a tensile strength of 2.0 kg / mm.²The elongation of the cured film is 65%, and the initial elastic modulus is 40.6 kg / mm.²Thus, it retains rubber-like properties and has high heat resistance with a thermal decomposition temperature of 461 ° C. Volume resistance is 10 even under humidification¹⁶It has a high Ω · cm and a low dielectric constant of 3.2, and retains excellent electrical properties as an insulating coating.
The latter also provides a film having excellent heat resistance, mechanical properties, electrical properties, and chemical resistance simply by removing the solvent at a temperature of 200 ° C. or lower. This membrane has a tensile strength of about 11.8 kg / mm²The elongation of the cured film is 14.2%, and the initial elastic modulus is 274 kg / mm.²As mentioned above, it has heat resistance of 5% mass reduction temperature of 515 ° C. and volume resistance is 10¹⁶It has Ω · cm and dielectric constant of 3.1 (25 ° C.) and 2.8 (200 ° C.) and has excellent electrical characteristics.
In the present invention, the masking material solution contains an antifoaming agent (lower alcohol, mineral oil, silicone resin, oleic acid, polypropylene glycol, etc.), thixotropic agent (silica fine powder, mica, talc, calcium carbonate, etc.), Resin-modifying silicone agents (such as silane coupling agents, silicone oils, silicone surfactants, silicone synthetic lubricating oils, etc.) can be added. For example, by adding silicone oil (polysiloxane) and silane coupling agent, defoaming (suppresses foaming at the time of curing), releasability (prevention of adhesion of conductive polymer), lubrication last name (into pores) Penetrability), electrical insulation (prevents leakage current), water repellency (prevents penetration of solution during polymerization of conductive polymer), braking / vibration resistance (opposite pressure when capacitor elements are stacked) Improvement of heat resistance and weather resistance of resin (introduction of crosslinking mechanism) can be expected.
Further, in the present invention, by using a composition comprising a soluble polyimide siloxane and an epoxy resin (Japanese Patent Laid-Open No. 8-253777 (US Pat. No. 5,643,986)), the same effect as the addition of the silicone oil (polysiloxane) is obtained. Can be obtained.
[Masking material application method]
Referring to a plan view (FIG. 5A) and a side view (FIG. 5B) showing an outline of an embodiment of an apparatus for applying a masking material to a substrate for a solid electrolytic capacitor (hereinafter simply referred to as a substrate) according to the present invention. explain.
The apparatus of FIG. 5 supplies the solution containing the masking material to the roll coating surface, applies the masking material to the substrate, and the masking material remaining on the roll surface during one rotation of the disk-shaped rotating roll (13). It is comprised so that one cycle of cleaning can be implemented.
In the figure, 11 is a metal guide for fixing one end of a plurality of solid electrolytic capacitor substrates (12a, 12b, 12c...) In a strip shape.
The substrate can be fixed to the metal guide (11) by electrical or mechanical joining. Examples of the joining method include soldering, joining with a conductive paste, ultrasonic welding, spot welding, electron beam welding, and the like.
The metal guide (11) linearly moves in the direction of the arrow on the rotating roll (13). Conventional means such as a motor, a belt, and a cylinder can be used as means (not shown) for moving the metal guide (11). The side surface of the substrate (12) can also be applied by adjusting the relationship between the traveling speed (V1) of the metal guide and the rotational speed (V2) of the rotating roll. That is, as shown in FIG. 6A, when the traveling speed (V1) of the metal guide is larger than the rotational speed (V2), the side surface of the front end portion in the traveling direction of the substrate can be applied, and the traveling speed (V1) of the metal guide. Is smaller than the rotation speed (V2), the side surface portion of the rear end portion in the traveling direction of the substrate can be applied (FIG. 6B).
Further, the apparatus of the present invention is provided with a mechanism capable of applying both sides and both sides of the substrate fixed to the metal guide by reversing the relative positional relationship between the metal guide and the rotating roll.
An example of such a mechanism is a metal guide reversing mechanism. The reversal can be performed by using a motor or a cylinder, or by providing a metal guide holding portion so as to be rotatable with respect to the longitudinal direction and rotating the holding portion halfway.
In order to apply the opposite surface of the substrate fixed to the inverted metal guide, it is necessary to adjust the relationship between the application surface of the rotating roll and the application position of the substrate, but can the metal guide be moved by conventional means? This can be done by moving the position of the rotating roll or by moving both.
Alternatively, two rotating rolls may be prepared, and the uncoated surface of the substrate fixed to the inverted metal guide may be applied with a dedicated rotating roll.
Furthermore, it is also possible to mask two surfaces and both side surfaces of a substrate fixed on a metal guide by installing two rotating rolls in a sandwiched arrangement.
The rotating roll (13) is a disk-shaped rotating roll having a smooth coating surface that contacts a desired portion of the substrate with a predetermined pressing force.
As the rotating roll (13), a metal (stainless steel or the like) or ceramic material made of a hard material resistant to a solution containing a masking material is used. The size is not limited in the present invention as long as the masking material does not change in quality during one rotation (one cycle of application of the masking material), and usually has a diameter of about 2 mm to about 500 mm. Moreover, the application surface width | variety of a roll is a width | variety which can apply a masking material to desired width, Preferably, it is about 0.2-3.0 mm.
Around the rotary roll (13), means (14) for supplying a solution containing a masking material to the coating surface behind the contact position with the substrate (rear in the rotation direction), and the contact position with the substrate (12) A scraper (15) and a wiping material (16) for cleaning the application surface of the rotary roll are disposed in front of the slab.
In this example, the means (14) for supplying the solution containing the masking material is a quantitative application liquid supply machine provided with a sealed quantitative continuous discharge dispenser with little pulsation. A predetermined amount of solution containing the masking material is continuously supplied to the roll coating surface by a discharge needle through a tube made of resin resistant to the solution containing the masking material from a fixed amount coating liquid supply machine.
Further, a fine adjustment mechanism for stabilizing the distance between the needle tip and the roll surface is provided in order to stably supply the solution containing the masking material to the application surface of the roll (13). An example of such a mechanism is to finely adjust the vertical position using a micrometer head (screw mechanism).
The application surface of the rotating roll (13) to which the solution containing the masking material is supplied comes into contact with the substrate with a constant pressing force at the contact position with the substrate. The pressing force at the time of contact is within the elastic limit of the substrate, and preferably, the amount of deflection at the smooth vertex (coating surface) of the rotating roll is in the range of about 0.03 to 0.3 mm. . Although the specific pressing force varies depending on the type and thickness of the substrate, it cannot be generally stated. For example, it is about 0.002 to 0.02 g / substrate (width 3 mm × thickness 0.1 mm).
Next, the roll application surface is cleaned. As the cleaning means, for example, a mechanical scraper (15) and a wiping material (16) are used.
The scraper (15) is a blade made of a material (resin, steel, etc.) made of the same quality as or softer than the roll of stainless steel, ceramics, etc., and is arranged so that at least the tip is in close contact with the application surface of the roll. The masking material remaining on the coated surface of the roll after coating the substrate is scraped off. A wiping material in which an organic solvent and / or water (the same solvent used in the masking material solution) is soaked in the resin fiber, disposed in front of the scraper (15) (forward in the rotation direction) In 16), the deposits on the roll coating surface are scraped off to prepare for the next coating cycle.
In this apparatus, the solution containing the masking material can be stably supplied from the sealed container to the application surface of the rotating roll by adopting a non-pulsating driving method.
[Solid electrolyte]
In the present invention, as the solid electrolyte, a conductive polymer having as a repeating unit at least one divalent group of pyrrole, thiophene, furan or aniline structure, or a substituted derivative thereof can be preferably used. Conventionally known materials can be used without particular limitation.
For example, a method in which a 3,4-ethylenedioxythiophene monomer and an oxidizing agent are preferably applied in the form of a solution, separately or together, and applied to an oxide film layer of a metal foil (JP-A-2-15611). Gazette (U.S. Pat. No. 4,910,645) and JP-A-10-32145 (European Patent Publication No. 820076 (A2))) can be used.
In general, an arylsulfonate salt dopant is used for the conductive polymer. For example, salts of benzenesulfonic acid, toluenesulfonic acid, naphthalenesulfonic acid, anthracenesulfonic acid, anthraquinonesulfonic acid, etc. can be used.
BEST MODE FOR CARRYING OUT THE INVENTION
Examples will be described below, but the present invention is not limited to the following examples.
Example 1:
Masking process
A 100-μm-thick chemical aluminum foil cut to 3 mm width (slit) is cut to a length of 13 mm, and one short side of this foil piece is fixed to a metal guide by welding, from the unfixed end A polyimide resin solution (made by Ube Industries, Ltd .; Iupicoat FS-100L) adjusted to a viscosity of 800 cP is supplied to a disc-shaped coating device having a coating surface width of 0.4 mm, and the coating surface of the coating device is The entire surface of the aluminum formed foil was contacted and pressed to draw a line with a width of 0.8 mm and dried at about 180 ° C. to form a masking layer (polyimide film).
Chemical treatment process
The part from the tip of the aluminum foil fixed to the metal guide removed from the coating device to the masking line is immersed in an aqueous solution of ammonium adipate and a voltage of 13 V is applied to form an unformed part of the cut part, thereby forming a dielectric. A film was formed.
Solid electrolyte formation process
A solid electrolyte was formed in the chemical conversion treatment layer region as follows.
That is, a portion (3 mm × 4 mm) opposite to the masking layer is immersed in an isopropanol solution (solution 1) containing 20% by mass of 3,4-ethylenedioxythiophene with a 4 mm masking layer as a boundary from the tip of the aluminum foil. , Pulled up and left at 25 ° C. for 5 minutes. Next, the aluminum foil portion treated with the monomer solution was immersed in an aqueous solution (solution 2) containing 30% by mass of ammonium persulfate, which was dried at 60 ° C. for 10 minutes to perform oxidative polymerization. The operation of immersing in solution 1 and then immersing in solution 2 and conducting oxidative polymerization was repeated 25 times to form a solid electrolyte layer.
Construction and testing of chip-type solid electrolytic capacitor elements
Three parts including the masking layer are overlapped with the silver paste on the lead frame, and the anode lead terminal is connected to the part without the conductive polymer by welding, and the whole is sealed with an epoxy resin at 120 ° C. A total of 30 chip-type solid electrolytic capacitors were produced by applying the rated voltage and aging for 2 hours. A cross-sectional view of the manufactured chip-type solid electrolytic capacitor is shown in FIG.
This capacitor element was subjected to a reflow test by passing it through a temperature range of 230 ° C. for 30 seconds, the leakage current one minute after application of the rated voltage was measured, and the average value of those having a measured value of 1 CV or less was obtained. .04 CV or higher was regarded as defective. These results are shown in Table 1.
Structural analysis of capacitor masking part
Capacitor material having a solid electrolyte layer formed of a sulfur-containing polymer (polymer of 3,4-ethylenedioxythiophene) layer as a solid electrolyte using aluminum foil as a metal material in the solid electrolyte formation step of Example 1 (Sample) was put in an epoxy resin (trade name: Quetol-812), cured at 30 to 60 ° C. for 20 to 30 hours to fix the sample, and then cut at a position corresponding to AA ′ in FIG. 1D. A photograph (magnification 500 times) around the masking portion is shown in FIG.
Cutting is performed on A-A ′ with a microtome, and the cut surface has a minute volume (1 μm).³A two-dimensional distribution state of a specific element was observed by a mapping method using an electron probe microanalyzer (EPMA), which is an apparatus for analyzing the composition of elements contained in the element. According to the above electron beam microanalyzer, the unit volume is 1 μm.³On the other hand, it is possible to quantitatively analyze elements of 1 to several percent (mass).
In the enlarged photograph, the aluminum core bar (1a), the dielectric layer (1b), the solid electrolyte (sulfur-containing polymer layer) (4) and the masking layer (2) can be observed.
(1a) and (1b) contain an aluminum element, (4) contains a sulfur element, and (4) and (2) contain a carbon element. Therefore, by examining elemental analysis of carbon, sulfur, aluminum, etc., the distribution of the masking material and the polymer was clarified in each of the parts (1a), (1b), (4), and (2). This is shown in FIG. 2 as a schematic diagram.
From the observation of the detection distribution of elemental sulfur (S), it was found that the area where the solid electrolyte (4) was distributed in the dielectric layer (1b) was clearly separated, and the masking material blocked the infiltration of the solid electrolyte. did. Here, “blocking intrusion” means that 5% by mass or more of the solid electrolyte material is not present in the permeation portion of the masking material. This value can be obtained, for example, from the detection limit value of the identification element by the electron beam microanalyzer and the content of the identification element in the solid electrolyte.
From the above results, when the capacitor element is formed by the solid electrolytic capacitor according to the present invention, the capacitor characteristics with improved leakage current, capacitance, etc. are obtained because the masking material penetrates into the dielectric film and the penetration portion However, it is considered that the solid electrolyte cannot be penetrated into the dielectric film infiltrated with the masking material and is completely blocked by the masking material formed on the infiltrating portion.
Example 2:
In Example 1, as a masking material, a polyimide resin solution (manufactured by Shin Nippon Rika Co., Ltd .; Rika Coat)^TMIn the same manner, a chip-type solid electrolytic capacitor was prepared, and the leakage current was measured and the reflow test was performed. The results are shown in Table 1.
Example 3:
In Example 1, the solution 2 in the solid electrolyte forming step was further immersed in an aqueous solution prepared such that sodium 2-anthraquinonesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) was 0.07% by mass, and oxidation polymerization was performed. Produced a chip-type solid electrolytic capacitor in the same manner, and similarly measured the leakage current and performed a reflow test. The results are shown in Table 1.
Example 4:
In Example 1, the solution 2 in the solid electrolyte formation step was further immersed in an aqueous solution prepared such that sodium 2-naphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) was 0.06% by mass to perform oxidative polymerization. Produced a chip-type solid electrolytic capacitor in the same manner, and similarly measured the leakage current and performed a reflow test. The results are shown in Table 1.
Example 5:
In Example 3, a chip-type solid electrolytic capacitor was produced in the same manner as in Example 3 except that N-methylpyrrole was used instead of 3,4-ethylenedioxythiophene, and the leakage current measurement and reflow test were performed in the same manner. Was done. The results are shown in Table 1.
Comparative Example 1:
Instead of forming the masking layer in Example 1, a chip-type solid electrolytic capacitor was produced in the same manner except that a tape made of a heat-resistant substrate and a heat-resistant adhesive was attached to the front and back of the aluminum foil with a width of 1 mm. Similarly, leakage current was measured and a reflow test was performed. The results are shown in Table 1. Similarly to Example 1, from the analysis of elemental sulfur by EPMA, the region where the solid electrolyte layer (4) is distributed in the dielectric layer (1b) is not clearly separated, and the solid electrolyte is formed in the masking layer. Was invading.
Comparative Example 2:
A chip-type solid electrolytic capacitor was prepared in the same manner as in Example 1, except that a phenol resin was applied and cured instead of forming a polymer insulating film and a line having a width of 0.8 mm was drawn on the front and back of the foil. Leakage current measurement and reflow test were performed. The results are shown in Table 1. Moreover, the solid electrolyte infiltrated into the masking layer from EPMA analysis as in Comparative Example 1.

Example 6:
First masking process
A 100-μm-thick chemical aluminum foil cut to 3 mm width (slit) is cut to a length of 13 mm, and one short side of this foil piece is fixed to a metal guide by welding, from the unfixed end Polyimide resin solution adjusted to a viscosity of 800 cp at 7 mm (made by Shin Nippon Rika Co., Ltd .; Rika Coat^TM) Is applied to a disk-shaped coating device having a coating surface width of 0.4 mm, and the coating surface of the coating device is brought into contact with and pressed against the entire circumference of the aluminum formed foil, and drawn in a line with a width of 0.8 mm. It dried at 180 degreeC and formed the 1st masking layer (polyimide film).
Chemical treatment process
The portion from the tip of the aluminum foil fixed to the metal guide removed from the coating apparatus to the first masking line is immersed in an aqueous solution of ammonium adipate and a voltage of 13 V is applied to form an unformed portion of the cut portion. A dielectric film was formed.
Second masking process
Next, the aluminum foil fixed to the metal guide is mounted on the coating device again, and a polyimide resin solution (manufactured by Shin Nippon Rika Co., Ltd .; Rika Coat) is placed in a location 4 mm from the unfixed tip.^TM) Was drawn linearly to a width of 0.8 mm and dried at about 180 ° C. to form a second masking layer (polyimide film).
Solid electrolyte formation process
A solid electrolyte was formed in the chemical conversion treatment layer region excluding the space between the first masking layer and the second masking layer as follows.
That is, an isopropanol solution containing 20% by mass of 3,4-ethylenedioxythiophene (3 mm × 4 mm) on the opposite side of the first masking layer (3 mm × 4 mm) with the 4 mm second masking layer as a boundary from the tip of the aluminum foil ( It was immersed in solution 1), pulled up and left at 25 ° C. for 5 minutes. Next, the aluminum foil part treated with the monomer solution was immersed in an aqueous solution (solution 2) containing 30% by mass of an aqueous ammonium persulfate solution, which was dried at 60 ° C. for 10 minutes to carry out oxidative polymerization. The operation of immersing in solution 1 and then immersing in solution 2 and conducting oxidative polymerization was repeated 25 times to form a solid electrolyte layer.
Cutting process
After attaching the carbon paste and the silver paste to the portion where the conductive polymer layer of the aluminum foil element having the solid electrolyte layer is formed, the aluminum foil is interposed between the first masking layer and the second masking layer. Was cut off.
Construction and testing of chip-type solid electrolytic capacitor elements
Three pieces of the cut portion including the second masking layer are laminated on the lead frame while being bonded with silver paste, and the anode lead terminal is connected to the portion not attached with the conductive polymer by welding, and the whole is sealed with epoxy resin. A total of 30 chip-type solid electrolytic capacitors were produced by applying a rated voltage at 120 ° C. and aging for 2 hours. A cross-sectional view of the manufactured chip-type solid electrolytic capacitor is shown in FIG.
This capacitor element was subjected to a reflow test by passing it through a temperature range of 230 ° C. for 30 seconds, the leakage current one minute after application of the rated voltage was measured, and the average value of those having a measured value of 1 CV or less was obtained. .04 CV or higher was regarded as defective. These results are shown in Table 2.
Example 7:
A chip-type solid electrolytic capacitor was prepared in the same manner as in Example 6 except that a polyimide resin solution (manufactured by Ube Industries, Ltd .; Iupicoat FS-100L) was used as the first masking material. Measurements and reflow tests were performed. The results are shown in Table 2.
Example 8:
In Example 6, as a first masking material and a second masking material, a polyimide resin solution (manufactured by Ube Industries, Ltd .; Iupicoat)^TMA chip-type solid electrolytic capacitor was produced in the same manner except that it was applied using FS-100L), and a leakage current measurement and a reflow test were conducted in the same manner. The results are shown in Table 2.
Example 9:
In Example 8, the solution 2 in the solid electrolyte formation step was further immersed in an aqueous solution prepared such that sodium 2-anthraquinonesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) was 0.07% by mass, and oxidation polymerization was performed. Produced a chip-type solid electrolytic capacitor in the same manner, and similarly measured the leakage current and performed a reflow test. The results are shown in Table 2.
Example 10:
In Example 8, the solution 2 in the solid electrolyte formation step was further immersed in an aqueous solution prepared such that sodium 2-naphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) was 0.06% by mass and subjected to oxidative polymerization. Produced a chip-type solid electrolytic capacitor in the same manner, and similarly measured the leakage current and performed a reflow test. The results are shown in Table 2.
Comparative Example 3:
A chip-type solid electrolytic capacitor was produced in the same manner as in Example 6 except that masking was performed once. That is, only the second masking step (position of 4 mm from the tip of the aluminum foil) is performed to form a polymer (polyimide) film, and then the chemical conversion treatment step, the solid electrolyte formation step, and the cutting step are performed. A solid electrolytic capacitor was produced, and leakage current was measured and a reflow test was performed. The results are shown in Table 2.
Comparative Example 4:
In Comparative Example 3, a chip-type solid electrolytic capacitor was formed in the same manner except that a tape made of a heat-resistant substrate and a heat-resistant adhesive was pasted on the front and back of the aluminum foil with a width of 1 mm instead of forming the second masking layer. The leakage current was measured and the reflow test was performed in the same manner. The results are shown in Table 2.
Comparative Example 5:
In Comparative Example 3, a chip-type solid electrolytic capacitor was prepared in the same manner except that a phenol resin was applied and cured instead of forming a polymer insulating film and a line having a width of 0.8 mm was drawn on the front and back of the foil. Leakage current measurement and reflow test were performed. The results are shown in Table 2.

Industrial applicability
Advantages of the manufacturing method of the solid electrolytic capacitor according to the present invention compared to the prior art are as follows.
(A) As a masking material, a polyimide resin is used instead of a conventional tape, epoxy, or phenolic resin, so that the surface of the dielectric film is sufficiently covered, and further in the dielectric film up to the core metal As a result of the structure in which the masking material penetrates sufficiently, the conductive polymer-impregnated part and the anode part are completely separated, the leakage current is reduced, and it occurs during the reflow process after capacitor element formation and element formation. Stress can be relaxed.
(B) By completely forming the cut portion of the conversion foil, an increase in leakage current due to penetration of the conductive polymer or conductive paste into the cut portion can be prevented.
(C) With the masking layer, the chemical conversion liquid can be surely and easily subjected to chemical conversion without causing the chemical conversion liquid to exude beyond the masking layer during the chemical conversion treatment in the next step. Further, since the masking material penetrates into the dielectric film and is formed on the permeation part, the solid electrolyte cannot permeate into the dielectric film permeated by the masking material and is formed on the permeation part. Since the masking material is masked by the masking material, the cathode part and the anode part can be reliably insulated.
(D) The polyimide film used as a masking material is resistant to organic solvents such as water or alcohol used during polymerization of the conductive polymer, penetrates into the dielectric film, and ensures insulation between the anode and cathode. Can be retained.
Further, according to the method of performing masking twice, the first masking layer (temporary masking layer) prevents the chemical conversion liquid from spreading over the masking layer during the chemical conversion treatment in the next step, and the necessary portions. The chemical conversion treatment can be reliably and easily performed (the portion excluding the anode portion of the solid electrolytic capacitor). That is, if there is no temporary masking layer, the chemical conversion liquid oozes over the substrate, and the leakage current during chemical conversion may increase, causing a short circuit with the electrode. If a long substrate (metal foil) is used and the distance between the chemical conversion solution and the electrode position is taken, the possibility of a short circuit can be reduced, but the economy and productivity are reduced. When the temporary masking layer is not provided, it is difficult to regulate the amount of the chemical conversion liquid so that the chemical conversion state cannot be managed. However, such a problem can be solved by performing the masking twice.
Furthermore, according to the masking material coating method and apparatus of the present invention, when the masking material for the solid electrolytic capacitor is applied to the substrate, the masking material (polyimide resin or the like) uniformly dissolved or dispersed in the solvent every time the roll is rotated once. ) In a straight line and continuously with a stable line width.
[Brief description of the drawings]
1A to 1D are schematic views of a manufacturing process of the solid electrolytic capacitor of the present invention.
FIG. 2 is a schematic view showing the structure of the masking layer of the solid electrolytic capacitor obtained by the method of the present invention.
FIG. 3 is a cross-sectional view of an example of a solid electrolytic capacitor element.
4A to 4F are schematic views of the manufacturing process of the solid electrolytic capacitor of the present invention when the two-stage masking process is performed.
FIG. 5 is a plan view (FIG. 5A) and a side view (FIG. 5B) showing an outline of an example of an apparatus for applying a masking material.
FIG. 6 is an explanatory diagram of the side surface coating of the substrate.
FIG. 7 is a cross-sectional view of the solid electrolytic capacitor element produced in the example.
FIG. 8 is an enlarged photograph showing a cross section around the masking portion of the capacitor coated with the masking material.

Claims (25)

In a method of manufacturing a solid electrolytic capacitor having a dielectric film and forming a solid electrolyte at a desired position on a metal material having a valve action, the dielectric film penetrates into the dielectric film and masks on the permeation part A method for producing a solid electrolytic capacitor, comprising: a step of applying a masking material solution for forming a layer; and a step of thermally modifying the masking material by heat treatment . In a method of manufacturing a solid electrolytic capacitor having a dielectric film and forming a solid electrolyte at a desired position on a metal material having a valve action, the dielectric film penetrates into the dielectric film and masks on the permeation part A step of applying a masking material solution for forming a layer and a step of heat-modifying and polymerizing the masking material by heat treatment, and the masking resin that has penetrated into the dielectric film and solidified in the coating step is a subsequent step. The manufacturing method of the solid electrolytic capacitor which prevents the penetration | invasion of the solid electrolyte formed in (3).   3. The method for producing a solid electrolytic capacitor according to claim 2, wherein the concentration of the solid electrolyte in the masking resin infiltrating portion of the dielectric film by the masking material solution coating step is not more than a detection limit value by an electron beam microanalyzer.   A plurality of solid electrolytic capacitor substrates are fixed to one end of a metal guide in a strip shape, and while moving the metal guide, a disk-shaped rotating roll is brought into contact with a desired portion of the substrate with a predetermined pressing force, The masking material solution supplied from the masking material solution supply means to the rotating roll coating surface is applied to both sides and both sides of the desired portion of the substrate for a solid electrolytic capacitor to form a masking layer. The manufacturing method of the solid electrolytic capacitor of description.   The method for producing a solid electrolytic capacitor according to claim 4, wherein the masking material solution is applied to both sides and both sides of the substrate fixed to the metal guide by reversing the relative positional relationship between the metal guide and the rotating roll.   In a method of manufacturing a solid electrolytic capacitor having a dielectric film and forming a solid electrolyte at a desired position on a metal material having a valve action cut into a predetermined shape, a masking material solution is applied on the metal material. A step of forming a first masking layer by coating and a step of forming a second masking layer, and penetrating into the dielectric film by at least the second masking layer forming step and on the penetrating portion The manufacturing method of the solid electrolytic capacitor of Claim 1 with which a masking layer is formed. In a method for manufacturing a solid electrolytic capacitor having a dielectric film and forming a solid electrolyte at a desired position on a metal material having a valve action cut into a predetermined shape,
A step of forming a first masking layer by applying a masking material solution linearly to the entire circumference of the boundary region where chemical conversion treatment is performed on the metal material, and heat-denaturing and polymerizing by heat treatment ;
Chemical conversion treatment of a region for forming a solid electrolyte separated by a region having the first masking layer of the metal material,
A masking material solution is further applied in a linear form to the entire circumference of the region on the metal material subjected to the chemical conversion treatment at a predetermined interval from the first masking layer, and heat-denatured by heat treatment to obtain a polymer . Forming a masking layer of
A step of forming a solid electrolyte in a region excluding a portion between the first masking layer and the second masking layer in the chemical conversion treatment region; and between the first masking layer and the second masking layer. The manufacturing method of the solid electrolytic capacitor of Claim 6 including the process of cut | disconnecting the said metal material in the area | region of this.   The method for producing a solid electrolytic capacitor according to any one of claims 1 to 7, wherein a solution of a heat resistant resin or a precursor thereof is used as the masking material solution.   The method for producing a solid electrolytic capacitor according to claim 8, wherein the solution of the heat resistant resin or the precursor thereof is a low molecular weight polyimide solution or a polyamic acid solution that is solidified by heating.   The method for producing a solid electrolytic capacitor according to claim 8 or 9, wherein the masking material solution further contains silicone oil, a silane coupling agent, or polyimidesiloxane.   The method for manufacturing a solid electrolytic capacitor according to any one of claims 1 to 7, wherein the metal material having a valve action is a material selected from aluminum, tantalum, niobium, titanium, zirconium, and alloys thereof.   8. The polymer solid electrolyte according to claim 1, wherein the solid electrolyte is a polymer solid electrolyte containing at least one of divalent groups of pyrrole, thiophene, aniline, and furan, or a substituted derivative thereof as a repeating unit. The manufacturing method of the solid electrolytic capacitor of description.   The method for producing a solid electrolytic capacitor according to claim 12, wherein the polymer solid electrolyte contains a polymer of 3,4-ethylenedioxythiophene.   The method for producing a solid electrolytic capacitor according to claim 12 or 13, wherein the solid electrolyte further contains an aryl sulfonate dopant.   A plurality of solid electrolytic capacitor substrates are fixed to one end of a metal guide in a strip shape, and while moving the metal guide, a disk-shaped rotating roll is brought into contact with a desired portion of the substrate with a predetermined pressing force, A masking material application method, comprising: applying a masking material solution supplied from a masking material solution supply means to a rotary roll application surface on both sides and both sides of a desired portion of the substrate for a solid electrolytic capacitor. The masking material application method according to claim 15 , wherein the masking material solution is applied to both sides and both side surfaces of the substrate fixed to the metal guide by reversing the relative positional relationship between the metal guide and the rotating roll.   Metal guide (11) for fixing one end of a plurality of substrates for solid electrolytic capacitors (12) in a strip shape, means for moving the metal guide, and contact with a desired location on the substrate (12) with a predetermined pressing force A disk-shaped rotating roll (13), a means (14) for supplying a solution containing a masking material to the application surface of the rotating roll, and a scraper (15) for cleaning the application surface of the rotating roll (13). A masking material coating apparatus for coating a masking material on both sides and both sides of a desired portion of the electrolytic capacitor substrate (12). 18. The masking material coating apparatus according to claim 17 , wherein the mask is applied to both sides and both sides of a substrate fixed to the metal guide by reversing the relative positional relationship between the metal guide and the rotating roll. The apparatus according to claim 17 , comprising two rotating rolls, and applying the opposite surface of the substrate fixed to the inverted metal guide with a dedicated rotating roll. The masking material coating apparatus according to claim 17 , wherein two masking materials are applied to both sides and both sides of a substrate fixed to a moving metal guide by providing two rotating rolls arranged so as to sandwich the substrate. Substrate is a valve metal material, the masking material application device according to any one of claims 17 to 20 coated surface of the rotating roll in contact with a pressing force within the elastic limit to the substrate. Masking material coating apparatus according to any one of claims 17 to 20 turn roll is a steel material or a ceramic material. The masking material coating apparatus according to any one of claims 17 to 22 , wherein the scraper is a resin blade that is in line contact with the rotating roll coating surface or a steel blade that is softer than the rotating roll material. The masking material coating apparatus according to any one of claims 17 to 23 , wherein a wiping material (16) in which an organic solvent and / or water is impregnated into a resin fiber is disposed in front of the scraper. The masking material application device according to any one of claims 17 to 24 , wherein the masking material supply means (4) is constituted by a quantitative continuous discharger and a tubular member.

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