JP4524873B2 - Multilayer solid electrolytic capacitor - Google Patents

Description

但し、上記の一般式（Ｉ）において、Ｒ¹及びＲ²は、各々独立して水素原子、Ｃ₁〜Ｃ₆の直鎖状もしくは分岐状の飽和もしくは不飽和の炭化水素基、またはＣ₁〜Ｃ₆の炭化水素基が互いに任意の位置で結合して、２つの酸素元素を含む少なくとも１つ以上の５〜７員環の飽和炭化水素の環状構造を形成する置換基を表す。また、前記環状構造には置換されていてもよいビニレン結合を有するもの、置換されていてもよいフェニレン構造のものが含まれる。
また、同様に下記の一般式（ＩＩ）の二価基の化学構造を含む重合体も、固体電解質４を形成するために好適に使用できる。
【００３７】
【化２】

上記の一般式（ＩＩ）において、Ｒ³、Ｒ⁴、Ｒ⁵及びＲ⁶は、それぞれ独立して、水素原子、Ｃ₁〜Ｃ₁₀の直鎖状もしくは分岐状の飽和もしくは不飽和のアルキル基、アルコキシ基またはアルキルエステル基、ハロゲン原子、ニトロ基、シアノ基、１級、２級または３級アミノ基、トリフロロメチル基、フェニル基及び置換フェニル基からなる群から選ばれる一価基を表すか、またはＲ³、Ｒ⁴、Ｒ⁵及びＲ⁶の炭化水素鎖は互いに任意の位置で結合して、かかる基により置換を受けている炭素原子と共に少なくとも１つ以上の３〜７員環の飽和または不飽和炭化水素の環状構造を形成する二価の基を形成してもよい。
【００３８】
また、一般式（ＩＩ）において、Ｒ³、Ｒ⁴、Ｒ⁵及びＲ⁶が表すアルキル基、アルコキシ基、アルキルエステル基、またはそれらによって形成される環状炭化水素鎖にはカルボニル、エーテル、エステル、アミド、スルフィド、スルフィニル、スルホニル、イミノ結合を任意の数含んでもよい。一般式（ＩＩ）に記載のδは、繰り返し単位あたりの荷電数を表し、０〜１の範囲である。
【００３９】
しかしながら、本発明の単板コンデンサ素子および積層型固体電解コンデンサにおいては、特に化学構造には限定されなく、通常固体電解質４を形成する材料の電気伝導度は、０．１〜２００Ｓ／ｃｍの範囲、望ましくは１〜１００Ｓ／ｃｍの範囲、さらに好ましくは１０〜１００Ｓ／ｃｍの範囲であればよい。
【００４０】
ピロールやチオフェン類等の複素五員環式化合物の酸化重合に対して適する酸化剤として、例えば特開平２−１５６１１号公報記載の塩化鉄（ＩＩＩ）、Ｆｅ（Ｃ１０₄）₃や有機酸鉄（ＩｌＩ）、無機酸鉄（ＩｌＩ）、アルキル過硫酸塩、過硫酸アンモニウム、過酸化水素等が広範に使用できる。前記有機酸鉄（Ｉｌｌ）の有機酸の例としては、メタンスルホン酸やドデシルベンゼンスルホン酸のような炭素数１〜２０のアルキルスルホン酸や同じく脂肪族カルボン酸が挙けられる。しかしながら、前記酸化剤の使用範囲は、詳細には前記モノマー化合物の化学構造と酸化剤および反応条件等の制限を受けることがある。例えば、チオフェン類の酸化（重合）は、Ｈａｎｄｂｏｏｋ ｏｆ Ｃｏｎｄｕｃｔｉｎｇ Ｐｏｌｙｍｅｒｓ誌（Ｍａｒｃｅｌ Ｄｅｋｋｅｒ，Ｉｎｃ．社発行、１９８７年、９９頁、図５参照。）の説明によると、置換基の種類により酸化電位（重合の起こり易さを示す１つの尺度。）が大きくかわり、重合反応を左右する（酸化電位は約ｌ．８〜約２．７Ｖの範囲に広範に広がっている。）。従って、具体的には使用するモノマー化合物と酸化剤、反応条件の組合せが重要である。
【００４１】
前記導電性重合体に含まれるドーパントは、用いるπ電子共役構造を有する重合体に制限されない。ドーパントは、通常アニオンであればよく、また該アニオンが低分子アニオンであっても高分子電解質等の高分子アニオンであってもよい。例えば、具体的には、ＰＦ₆ ^-、ＳｂＦ₆ ^-、ＡｓＦ₆ ^-の如き５Ｂ族元素のハロゲン化物アニオン、ＢＦ₄ ^-の如き３Ｂ族元素のハロゲン化物アニオン、Ｉ^-（Ｉ₃ ^-）、Ｂｒ^-、Ｃｌ^-の如きハロゲンアニオン、ＣｌＯ₄ ^-の如き過ハロゲン酸アニオン、ＡｌＣｌ₄ ^- ＦｅＣｌ₄ ^- ＳｎＣｌ₅ ^-等の如きルイス酸アニオン、あるいはＮＯ₃ ^-、ＳＯ₄ ^2-の如き無機酸アニオン、またはｐ−トルエンスルホン酸やナフタレンスルホン酸、Ｃ₁〜Ｃ₅のアルキル置換ナフタレンスルホン酸、ＣＦ₃ＳＯ₃ ^-、ＣＨ₃ＳＯ₃ ^-のごとき有機スルホン酸アニオン、またはＣＨ₃ＣＯＯ^-、Ｃ₆Ｈ₅ＣＯＯ^-のごときカルボン酸アニオン等のプロトン酸アニオンを挙げることができる。
【００４２】
さらに好ましくは、有機スルホン酸アニオン、有機リン酸アニオン等が使用される。特に有機スルホン酸アニオンであっては、芳香族スルホン酸アニオン、芳香族ポリスルホン酸アニオン、ＯＨ基またはカルボキシ基が置換した有機スルホン酸アニオン、アダマンタン等の骨格を有する脂肪族の有機スルホン酸アニオン等の種々の化合物が適用できる。
【００４３】
例えば、有機スルホン酸を例示すれば、ベンゼンスルホン酸やｐ−トルエンスルホン酸、メタンスルホン酸、エタンスルホン酸、α−スルホ−ナフタレン、β−スルホ−ナフタレン、ナフタレンジスルホン酸、アルキルナフタレンスルホン酸（アルキル基としてはブチル、トリイソプロピル、ジ−ｔ−ブチル等）が挙げられる。
また、他の例示として、一つ以上のスルホアニオン基とキノン構造を分子内に有するスルホキノン化合物のアニオン（以下スルホキノンアニオンと略する）、アントラセンスルホン酸アニオン、ナフタレンスルホン酸アニオン、ベンゼンスルホン酸アニオン、キシリレンジスルホン酸アニオン（ｏ、ｐ、ｍ）を例示することができる。
【００４４】
スルホキノンアニオンの基本骨格としては、ｐ−ベンゾキノン、ｏ−ベンゾキノン、１，２−ナフトキノン、１，４−ナフトキノン、２，６−ナフトキノン、９，１０−アントラキノン、１，４−アントラキノン、１，２−アントラキノン、１，４−クリセンキノン、５，６−クリセンキノン、６，１２−クリセンキノン、アセナフトキノン、アセナフテンキノン、カルホルキノン、２，３−ボルナンジオン、９，１０−フェナントレンキノン、２，７−ピレンキノンが挙げられる。
【００４５】
中でも、本発明において使用するスルホキノンとしては、アントラキノン、１，４−ナフトキノン、２，６−ナフトキノンの骨格を有するスルホキノンが好ましく使用される。例えばアントラキノン類の場合、アントラキノン−１−スルホン酸、アントラキノン−２−スルホン酸、アントラキノン−１，５−ジスルホン酸、アントラキノン−１，４−ジスルホン酸、アントラキノン−１，３−ジスルホン酸、アントラキノン−１，６−ジスルホン酸、アントラキノン−１，７−ジスルホン酸、アントラキノン−１，８−ジスルホン酸、アントラキノン−２，６−ジスルホン酸、アントラキノン−２，３−ジスルホン酸、アントラキノン−２，７−ジスルホン酸、アントラキノン−１，４，５−トリスルホン酸、アントラキノン−２，３，６，７−テトラスルホン酸、これらのアルカリ金属塩、及びこれらのアンモニウム塩等が使用できる。
【００４６】
１，４−ナフトキノン類の場合は、１，４−ナフトキノン−５−スルホン酸、１，４−ナフトキノン−６−スルホン酸、１，４−ナフトキノン−５，７−ジスルホン酸、１，４−ナフトキノン−５，８−ジスルホン酸、これらのアルカリ金属塩、及びこれらのアンモニウム塩等が使用できる。
２，６−ナフトキノン類の場合は、２，６−ナフトキノン−１−スルホン酸、２，６−ナフトキノン−３−スルホン酸、２，６−ナフトキノン−４−スルホン酸、２，６−ナフトキノン−３，７−ジスルホン酸、２，６−ナフトキノン−４，８−ジスルホン酸、これらのアルカリ金属塩、及びこれらのアンモニウム塩等が使用できる。
【００４７】
また、前記スルホキノンとしてはさらに工業的な染料の中から、例えばアントラキノンアイリスＲ、アントラキノンバイオレットＲＮ−３ＲＮがあり、これらも同様に有用なスルホキノン系ドーパントとして前記塩の形態で使用できる。
さらには、ポリアクリル酸、ポリメタクリル酸、ポリスチレンスルホン酸、ポリビニルスルホン酸、ポリビニル硫酸、ポリ−α−メチルスルホン酸、ポリエチレンスルホン酸、ポリリン酸等の高分子電解質アニオンも使用される。
【００４８】
また、これらのドーパントは、前記導電性重合体を産生しうる公知な酸化剤の還元体アニオンも含まれる。例えば、アルカリ金属過硫酸塩類や過硫酸アンモニウム塩類等の酸化剤の産生アニオンである硫酸イオンが挙げられる。その他には、過マンガン酸カリウム等のマンガン類、２，３−ジクロロ−５，６−ジシアノ−１，４−ベンゾキノン（ＤＤＱ）、テトラクロロ−１，４−ベンゾキノン、テトラシアノ−１，４−ベンゾキノン等のキノン類から産生されるドーパントが挙げられる。
【００４９】
以上、本発明においては導電性重合体に前記ドーパントの少なくとも１種を含むものが好適に使用される。例えば、導電性重合体にドーパントとして硫酸イオンがπ共役構造の全繰り返し単位に対して０．０１〜１０モル％の範囲であり、他のドーパントとして前記スルホキノンアニオン、例えばアントラキノンスルホン酸アニオンが１〜５０モル％の範囲を含むものである。
【００５０】
一方、単板コンデンサ素子について更に説明する。
単板コンデンサ素子として、図１、２に示すように、陰極部先端部分の厚みが陰極部基部の厚みよりも大きい先太形状のものを用いると、積層型固体電解コンデンサとしてこれを積層した場合、積層コンデンサ素子１９が末広がり形状となり易い。即ち、単板コンデンサ素子７の形状として、固体電解質層４と導電体層５、６との合計厚みを、図１に示すように、陰極部先端に向かって漸次大きくした形状、或いは、その厚さを図２に示すように陰極部先端に向かって階段状に厚くした形状が好ましい。
さらに別の発明の実施態様として、先太形状の単板コンデンサ素子において、陰極部基部の厚みＳ₁と、その先端部の最大厚みＳ₂との比Ｓ₂／Ｓ₁が１．１〜５．０の範囲が良く、より好ましくは１．３〜３．０の範囲である。
【００５１】
図１に示す形状の単板コンデンサ素子７を得る方法の例として、導電ペーストを塗布後先端側の導電体層５、６が厚くなるように機械的に加圧成型する方法が挙げられる。他の方法として、素子７の先端部に繰り返し導電ペーストを塗布して、図１、２に示すように、漸次に或いは階段状に導電体５、６を厚くする方法が挙げられる。素子７の先端部分を陰極部基部の厚みＳ₁よりも大きくできる方法であれば、どのような方法を用いてもよい。
【００５２】
単板コンデンサ素子を積層する方法は、例えば１枚毎に陰極側のリードフレーム上に導電ペーストを用いて積層してもよいし、また２枚以上をあらかじめ末広がり形状に積層した積層品を陰極側リードフレームに接着により積層してもよい。更にそれらの素子を重ねて積層してもよい。これら以外の積層方法を採用してもよい。またリードフレームの表裏の一方（例えば図４参照）、あるいは、表裏両側（例えば図５、図６、図８を参照）に単板コンデンサ素子を積層してもよい。
【００５３】
単板コンデンサ素子において先太ではなく、素子上下面がほぼ平行である単板コンデンサ素子を用いて末広がり形状に積層してもよく、その積層コンデンサ素子を得る方法として、導電性接着層の厚みを陰極部先端側において陰極部基部側よりも大きくする方法が挙げられる。
【００５４】
陰極部と陰極部との間の導電性接着層、及び陰極部と陰極側リードフレームとの間の導電性接着層は、陰極部の先端から陰極部長Ｌ（図１参照）の８０％迄の範囲（即ち、導電性接着層の陰極部先端からの長さＬ₁は、０．８×Ｌ以下）に形成されることが好ましい。先端から８０％迄の範囲を越えて導電性接着層を形成しようとすると、導電ペーストが積層時に陽極部迄に到達する恐れあり、ショート等による歩留悪化やショートにならなくても漏れ電流が大きくなる等の性能低下を招く恐れがある。導電性接着層を陰極部長さＬの８０％迄の範囲に形成するには、導電ペーストを陰極部長さの先端側から半長迄の範囲に塗布するがよい。
【００５５】
また、複数の単板コンデンサ素子が、機械的に加圧積層されことで末広がり形状の積層コンデンサ素子とされることが好ましい。即ち、複数の単板コンデンサ素子を導電ペーストで陰極側リードフレーム上に積層する時に、適当な圧力で単板コンデンサ素子を加圧板で加圧して導電ペーストの厚みを調節とすることで、所定寸法の末広がり形状とする。
【００５６】
この際、導電性接着層の厚みを、陰極部基部から陰極部先端部分に向かって漸次大きくなるようにすれば、積層コンデンサ素子の陰極部先端部分の厚みが陰極部基部の厚みよりも大きくなり、その結果、積層コンデンサ素子が末広がり形状となり易い。 例えば、図６や図８に見られるように、積層コンデンサ素子１９の末広がり形状として、積層コンデンサ素子１９の陰極部基部の厚みＷ₁と、該素子１９の陰極部先端部分の最大厚みＷ₂との比Ｗ₂／Ｗ₁は１．３〜５．５の範囲がよく、好ましくは１．５〜３．５の範囲がさらに好ましい。
単板コンデンサ素子の陽極部は、単板コンデンサ素子の積層後に折り曲げていてもよいし、その積層前に予め折り曲げられてもよい。
【００５７】
陽極部と陽極部との間及び陽極部と陽極側リードフレームとを接続する方法は、スポット溶接、レーザー溶接及び導電ペーストでの接続等、いかなる方法を採用してもよい。陰極部の積層と陽極部接続の順序も特に限定はなく、どちらを先にしてもよいし、また交互に行ってもよい。いずれにしても、単板コンデンサ素子７に大きな機械的応力が加わらないように積層して積層コンデンサ素子を作製することが肝心である。
【００５８】
積層コンデンサ素子は、外装樹脂で封口し、外装樹脂の外側のリードフレームを外装樹脂に沿って折曲げて外部リードとして積層型固体電解コンデンサとされる。外装樹脂の例はエポキシ樹脂、フェノール樹脂等であり、外部リードは、例えば材質（４２アロイ）で構成できる。
単板コンデンサ素子の陽極部を同一方向に揃え陽極側リードフレーム上に積層固着すると、或いは、先太形状の単板コンデンサ素子を用いると、積層コンデンサ素子が外装樹脂からはみ出さないようにでき、かつ単板コンデンサ素子の積層枚数を増やして高容量の積層型固体コンデンサを得ることができる。
【００５９】
本発明においては、前記積層構造を工夫することによって定格仕様で求められているコンデンサチップサイズに製造することができる。例えば、本発明の積層構造を適用することによって、コンデンサチップの単位体積当たりのＣＶ値が７．１×１０³Ｖ・Ｆ／ｍ³（または７．１×１０^-3Ｖ・Ｆ／ｃｍ³以上に相当する）、好ましくは７．３×１０³Ｖ・Ｆ／ｍ³以上、さらに好ましくは７．８×１０³Ｖ・Ｆ／ｍ³以上の固体電解コンデンサを提供することができる。
例えば、定格6.3V/100μF仕様の固体電解コンデンサとして、Ｄケースサイズ（0.73cm × 0.43cm ×高さ0.29cm ）で単位体積当たりのＣＶ値が７．１×１０³Ｖ・Ｆ／ｍ³以上の固体電解コンデンサを製造することができる。
【００６０】
【実施例】
本発明を実施例で説明するが、本発明はこれらの実施例のみに限定されるものではない。
以下の実施例において、実施例２、実施例４、実施例５は参考例として示す。
実施例１：先太形状の単板コンデンサ素子の製造表面にアルミナの誘電体酸化皮膜層２を有する厚さ９０μｍ、長さ５ｍｍ、幅３ｍｍのアルミニウム（弁作用金属）のエッチング箔（陽極基体１）の上端の長さ２ｍｍ、幅３ｍｍの部分を陽極部１１とし、残り３ｍｍ×３ｍｍの部分を、１０質量％のアジピン酸アンモニウム水溶液で１３Ｖ化成して切り口部に誘電体酸化皮膜層２を形成し、誘電体を準備した。この誘電体表面に、過硫酸アンモニウム２０質量％とアントラキノン−２−スルホン酸ナトリウム０．１質量％になるように調製した水溶液を含浸させ、次いで３，４−エチレンジオキシ−チオフェンを５ｇ溶解した１．２モル／ｌのイソプロパノール溶液に浸漬した。この基板を取り出して６０℃の環境下で１０分放置することで酸化重合を完成させ、水で洗浄した。この重合反応処理及び洗浄工程をそれぞれ１０回繰り返し、導電性高分子の固体電解質層４を形成した。
【００６１】
次いで、カーボンペースト槽に浸漬し固化させて導電体層５を形成した。そして、銀ペースト槽に浸漬し固化する操作を繰り返して導電体層６の厚みを先端に向かって漸次大きくすることで、図１に示す先太形状の単板コンデンサ素子７を得た。該単板コンデンサ素子７の陰極部基部の厚みＳ₁と、その先端部の最大厚みＳ₂との比Ｓ₂／Ｓ₁は２．１であった。
【００６２】
実施例２
本例の積層コンデンサ素子は、図４に略図を示すものである。実施例１の方法で製造した単板コンデンサ素子を３枚準備し、図４に示すように、３個の陽極部１１を左方に揃え、３個の陰極部を右方に揃えて、陰極部と陰極部との間、及び、陰極部とリードフレーム８との間を導電ぺーストで固体電解質層を有する部分の平板状弁作用金属が陰極側リードフレーム８に対してそれぞれほぼ平行に積層して積層コンデンサ素素子を得た。該積層品の陽極部１１を折り曲げながら、陽極部１１同士、及びリードフレーム９の片表面と陽極部１１の下面をスポット溶接することで、図４に示す積層コンデンサ素子を得た。
また、導電ぺーストの塗布長は、先端から陰極部長さＬの８０％迄とした。
【００６３】
実施例３：
本例の積層コンデンサ素子は図６に示すものである。実施例１の方法で製造した単板コンデンサ素子を６枚準備し、このうち３枚について３個の陽極部１１を左方に揃え、３個の陰極部を右方に揃えて、陰極部と陰極部との間、及び、陰極部とリードフレーム８との間を導電ぺーストで接着し、３枚積層の積層コンデンサ素子を作製した。導電ぺーストの塗布長は、先端から陰極部長さＬの５０％迄とした。同じ方法で、２つの３枚積層の積層コンデンサ素子を作製後、これらの積層コンデンサ素子を図６の構造のように向かい合わせて陰極リードフレーム８を介して接着固着した。このような積層構造により作製された積層型コンデンサは、より小型で小さい容積に最密積層することができた。
【００６４】
実施例４
本例の積層コンデンサ素子は、図７に略図を示すものである。実施例１の方法で製造した単板コンデンサ素子を６枚準備し、図７に示すように、単板コンデンサ素子を１枚ずつ交互に陽極部を対向して３枚の単板コンデンサ素子を積層した。このような積層コンデンサ素子を２つ作製後、これらの積層コンデンサを陰極側リードフレームの表裏の導電性接着層を形成して順次積層固着した。このとき、陽極部は同一方向の陽極側リードフレーム上に陽極部を必要に応じて折り曲げて積層固着され、複数の単板コンデンサ素子の陰極部は導電性接着層を形成して順次積層固着した。導電ぺーストの塗布長は、先端から陰極部長さＬの５０％迄とした。
【００６５】
実施例５
本例の積層コンデンサ素子は、図８に略図を示すものである。実施例１の方法を採用して、２対の固体電解質層の長さの異なる単板固体電解コンデンサを３種作製した。図８に示すように、固体電解質層の長さの最も短い単板固体電解コンデンサを取り出し、リードフレーム８上に導電ぺーストで接着し、そしてその上に該コンデンサよりも長い単板固体電解コンデンサを、陽極部１１を左方に揃え、陰極部を右方に揃えて、陰極部と陰極部との間に導電性接着層を介して３枚順次積層固着した。同じ積層構造をリードフレーム８の裏側に対して接着し、リードフレームの表裏に合計６枚の単板固体電解コンデンサを載置した。該積層品の陽極部１１は必要に応じて折り曲げながら、陽極部１１同士、及びリードフレーム９の片表面と陽極部１１の下面をスポット溶接することで、図８に示す積層コンデンサ素子を製造した。また、導電ぺーストの塗布長は、先端から陰極部長さＬの５０％迄とした。
【００６６】
固体電解質層の長さの異なる単板固体電解コンデンサは、固体電解質層を製造する際に使用する酸化剤浴（実施例１に記載の過硫酸アンモニウム／アントラキノン−２−スルホン酸ナトリウムからなる水溶液）及びモノマー浴（実施例１に記載の３，４−エチレンジオキシ−チオフェンのイソプロパノール溶液）への浸漬長さを制御して達成した。
【００６７】
実施例６：コンデンサ特性の評価
実施例２〜５に記載の積層構造を有する積層型コンデンサを１評価ユニットとして各３０チップ（ｎ＝３０）製造したのち、歩留（％）とリフロー試験後の漏れ電流により特性評価し、その結果を表１にまとめた。
【００６８】
【表１】

【００６９】
実施例７：小型大容量コンデンサの評価
小型大容量化評価の一例として、実施例３の方法に準じ８枚積層型固体電解コンデンサを作製した。但し、このコンデンサの製造においては、定格6.3ＶのＤケースサイズ（0.73ｃｍ × 0.43ｃｍ ×高さ0.2９ｃｍ ）で作製した。ここで製造された小型大容量コンデンサのＣＶ値評価をし、その結果を表２に記載した。
【００７０】
【表２】

【００７１】
【発明の効果】
本発明の積層構造によれば、小型大容量型素子の製造が可能であり、例えば、定格6.3V/100μF仕様の固体電解コンデンサとして、Ｄケースサイズで単位体積当たりのＣＶ値が７．１×１０³Ｖ・Ｆ／ｍ³以上の固体電解コンデンサを容易に製造することができる。また本発明の積層構造により、歩留、耐熱性に優れた積層型コンデンサ素子が得られる。また、歩留まり向上により該コンデンサの製造コストの大幅な削減が可能である。
【００７２】
【図面の簡単な説明】
【図１】 本発明において使用される単板コンデンサ素子の一例を示す断面略図である。
【図２】 本発明において使用される単板コンデンサ素子の一例を示す断面略図である。
【図３】参考例として示す単板コンデンサ素子の一例を示す断面略図である。
【図４】参考例として示す積層コンデンサ素子の例を示す断面略図である。
【図５】参考例として示す積層コンデンサ素子の例を示す断面略図である。
【図６】 本発明の積層コンデンサ素子の例を示す断面略図である。
【図７】参考例として示す積層コンデンサ素子の例を示す断面略図である。
【図８】参考例として示す積層コンデンサ素子の例を示す断面略図である。
【００７３】
【符号の説明】
１・・陽極基体、２・・誘導体酸化皮膜層、３・・絶縁層、４・・固体電解質層、５・・導電体層（カーボンペースト層）、６・・導電体層（銀ペースト層）、７・・単板コンデンサ素子、８・・陰極側リードフレーム、９・・陽極側リードフレーム、１０・・導電性接着層、１１・・陽極部、１２・・外部リード、１３・・溶接部、１４・・積層コンデンサ素子、１５・・外装樹脂、１６・・積層型固体電解コンデンサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a small-sized and large-capacity solid electrolytic capacitor. The present invention also relates to a multilayer solid electrolytic capacitor of a solid electrolytic capacitor using an organic material such as a conductive polymer or an inorganic material such as a metal oxide as a solid electrolyte.
[0002]
[Prior art]
In the demand for downsizing of electronic devices, downsizing and large capacity of solid electrolytic capacitors are required. In order to make a solid electrolytic capacitor more compact and large-capacity, it depends on the size and capacity of a single-plate solid electrolytic capacitor element itself contained and the closest packing method of the single-plate elements in a limited size. To do. In a commercially available aluminum solid electrolytic capacitor, the CV value per unit volume of the solid electrolytic capacitor is 7.0 × 10^ThreeVF / m^ThreeSolid electrolytic capacitors are known.
[0003]
The solid electrolytic capacitor generally includes an anode portion made of a flat valve action metal having a dielectric oxide film layer on the surface, and a solid electrolyte layer and a conductor layer thereon are sequentially formed on the dielectric oxide film layer. At least one layer of a single plate capacitor element formed and having a cathode portion is formed, and the periphery of the capacitor element is molded by being covered and sealed with an exterior resin. An organic substance such as a conductive polymer or an inorganic substance such as a metal oxide is used for the solid electrolyte layer.
[0004]
In the lamination of a solid electrolytic capacitor using a conductive polymer (or conductive polymer) or the like as a solid electrolyte, the solid electrolyte layer of the single-plate capacitor element and the cathode portion for sequentially forming the conductor layer are compared with the anode portion. Therefore, it is necessary to bend the anode parts so that they can be spot-welded when the cathode parts are stacked in parallel up and down. For this reason, there is a problem that stress concentration occurs in the vicinity of the boundary between the anode part and the cathode part of the single-plate capacitor element and the capacitor performance deteriorates, and various contrivances have been made so far.
[0005]
For example, in order to eliminate the step between the negative and positive electrodes, a method of inserting a metal plate having a thickness corresponding to the gap between the anode portions of a plurality of single-plate capacitor elements when the single-plate capacitor elements are stacked (Japanese Patent Laid-Open No. Hei 5). -205984, etc.), a method of forming an insulating resin layer in the gap between the anode parts and connecting with a thin metal wire (JP-A-6-29163, JP-A-6-84716, etc.) There is a method of dividing processing corresponding to the position of the anode part (JP-A-4-167417, etc.).
[0006]
[Problems to be solved by the invention]
In order to reduce the size and capacity of a solid electrolytic capacitor, as described above, it is necessary to reduce the size and capacity of a single-plate solid electrolytic capacitor element itself, and how to use it in a limited size (standard specification size, etc.). A major issue is how close the single-layer solid electrolytic capacitor elements are stacked in a limited size to realize a large capacitance as the solid electrolytic capacitor.
More specifically, when laminating single-plate solid electrolytic capacitor elements, stress concentration occurs near the boundary between the anode part and the cathode part, and a method for eliminating the step to prevent the stress concentration is a problem. . However, the method of eliminating the step increases the cost such as an increase in the process or the material processing cost, and the addition of the process increases the destruction of the single plate capacitor element due to the mechanical stress during the handling or the deterioration of the performance. There were problems such as poor yield and poor performance.
[0007]
The present invention solves these problems, and prevents a decrease in yield in the production of a multilayer capacitor and a small high-capacitance multilayer by preventing stress concentration occurring near the boundary between the anode and cathode during lamination. An object of the present invention is to provide a solid electrolytic capacitor.
[0008]
[Means for Solving the Problems]
  The present invention is a multilayer solid electrolytic capacitor in which single plate capacitor elements are laminated, and comprises the following inventions.
  (1) An end portion of an anode substrate made of a flat valve action metal having a dielectric oxide film layer on the surface is used as an anode portion, and a solid electrolyte layer is formed on the dielectric oxide film layer in a portion excluding the anode portion. A single plate capacitor element is composed of a cathode portion on which conductive layers are sequentially formed., The cathode part of the single-plate capacitor element has a shape spreading toward the tip of the cathode part from the anode part side,A plurality of the elements are aligned in the same direction and laminated in a divergent shape from the anode side toward the tip of the cathode part, and the anode part is laminated and fixed on the anode side lead frame to form a multilayer capacitor element. Two of the elements have the cathode part and the anode part in different directions, and the cathode parts of the conductor layers are bonded and fixed via a cathode-side lead frame, and the cathode part joining surface of the two multilayer capacitor elements and the cathode A multilayer solid electrolytic capacitor characterized in that the side lead frame is parallel.
[0009]
  (2) In the multilayer capacitor element, the length of the solid electrolyte of each single-plate capacitor element of one multilayer capacitor element and each single-plate capacitor element of the other multilayer capacitor element is not the same ( A multilayer solid electrolytic capacitor as described in 1).
  (3) The multilayer solid electrolytic capacitor as described in (1) or (2) above, wherein the conductive adhesive layer is formed in a range from the tip of the cathode portion to 80% of the length of the cathode portion.
[0010]
  (4) The multilayer solid electrolytic capacitor as described in any one of (1) to (3) above, wherein the multilayer capacitor element is obtained by pressure laminating a plurality of single plate capacitor elements. .
  (5) The thickness of the conductive adhesive layer of the single-plate capacitor element is laminated and fixed between the cathode part and the cathode part of the plurality of single-plate capacitor elements and between the cathode part and the cathode-side lead frame by the conductive adhesive layer. The multilayer solid electrolytic capacitor as described in any one of (1) to (4) above, wherein is larger at the tip of the cathode than at the base of the cathode.
[0011]
  (6) The multilayer solid electrolytic capacitor as described in any one of (1) to (5) above, wherein the solid electrolyte layer is formed using a conductive polymer.
  (7) The conductive polymer is a polymerizable hetero five-membered cyclic compound, aniline, benzene, p-phenylene vinylene, thienylene vinylene, isothianaphthene, naphtho [2,3-c] thiophene and substituted derivatives thereof. The multilayer solid electrolytic capacitor as described in (6) above, which is a polymer containing at least one chemical structure selected from the group consisting of divalent group chemical structures.
[0012]
  (8) The multilayer solid electrolytic capacitor as described in (7) above, wherein the polymerizable hetero five-membered cyclic compound is 3,4-ethylenedioxy-thiophene or a substituted derivative thereof.
  (9) The multilayer solid electrolytic capacitor according to any one of (1) to (8), wherein a plurality of single plate capacitor elements are in a range of 2 to 20.
[0013]
  (10) The multilayer solid electrolytic capacitor according to any one of (1) to (9), wherein the means for aligning the anode portions in the same direction and stacking and fixing them on the anode-side lead frame is spot welding.
  (11) CV value per unit volume is 7.1 × 10^ThreeVF / m^ThreeThe multilayer solid electrolytic capacitor as described in any one of (1) to (10) above.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 are schematic cross-sectional views showing examples of single plate capacitor elements preferably used in the present invention. In FIG. 1, the single-plate capacitor element has an anode portion 11 at the end of an anode substrate 1 made of a flat valve-acting metal having a dielectric oxide film layer 2 on the surface, and the anode portion 11 and the insulating layer 3. The solid oxide layer 4 and the conductor layers 5 and 6 are sequentially formed on the dielectric oxide film layer 2 except the portion, and this portion is used as a cathode portion, and the thickness S of the tip portion of the cathode portion is set.₂Is the thickness S of the cathode base₁A single plate capacitor element having a larger thickness than the anode portion 11 toward the tip of the cathode portion.
[0015]
  The single plate capacitor element shown in FIG. 2 is an example of a single plate capacitor element in which the thickness of the cathode portion is increased stepwise.TheThe single plate capacitor element shown in FIG. 3 is an example of a single plate capacitor element whose top and bottom surfaces of the element are not parallel but substantially parallel.For your referenceis there.The single plate capacitor element shown in FIGS. 1 and 2 is used in the multilayer solid capacitor of the present invention.
[0016]
  FIG. 4 or FIG.Show for referenceFIG. 2 is a schematic cross-sectional view showing an example of a multilayer solid electrolytic capacitor, and shows a multilayer solid electrolytic capacitor obtained by using a multilayer capacitor element in which a plurality of single-plate capacitor elements shown in FIG. 1 are stacked. For example, in FIG. 4, the end portion of the anode substrate 1 made of a flat valve-acting metal having a dielectric oxide film layer on the surface is an anode portion 11, and the dielectric oxide film in the portion excluding the anode portion. A plurality of single-plate capacitor elements 7 in which a solid electrolyte layer is formed on a layer and a carbon paste conductor layer and a silver paste conductor layer 6 are sequentially formed thereon to serve as a cathode portion have the same anode portion 11. Stacked and fixed on the anode-side lead frame 9 in the same direction, and the cathode part is formed in a divergent shape from the anode part side toward the tip of the cathode part, and a conductive adhesive layer 10 is formed on the cathode-side lead frame 8 and stacked and fixed. In the multilayer capacitor element, the flat valve-acting metal in the portion having the solid electrolyte layer of each single-plate capacitor element 7 is laminated substantially in parallel to the cathode-side lead frame 8. (Also referred to as a short parallel stacked.) Stacked solid electrolytic capacitor shows the.
[0017]
  FIG. 6 shows the present invention.Product ofFIG. 2 is a schematic cross-sectional view showing an example of a layered solid electrolytic capacitor, in which two laminated capacitor elements 19 in which a plurality of single-plate capacitor elements 7 shown in FIG. 1 is a schematic cross-sectional view of a multilayer solid electrolytic capacitor. For example, in FIG. 6, the end portion of the anode base 1 made of a flat valve-acting metal having the dielectric oxide film layer 2 on the surface is the anode portion 11, and the dielectric oxidation of the portion excluding the anode portion is performed. A plurality of single-plate capacitor elements 7 in which a solid electrolyte layer 4 is sequentially formed on a coating layer and conductor layers 5 and 6 are sequentially formed thereon are used as a cathode portion. A conductive adhesive layer 10 is formed on the cathode side lead frame 8 so as to be laminated and fixed on the frame 9, and the cathode part is widened from the anode side to the tip of the cathode part. Two multilayer capacitor elements 19 are prepared, and the cathode portion of the conductor layer is bonded and fixed to the anode portions 11 in different directions via the cathode-side lead frame 8. Electrolytic capacitor( And also referred to as a counter stacked with.) Shows a.
[0018]
  FIG.Show for referenceFIG. 2 is a schematic cross-sectional view showing an example of a multilayer solid electrolytic capacitor, in which single plate capacitor elements 7 are alternately laminated in a direction in which anode parts 11 are opposed to each other, and anode parts that are alternately laminated in the same direction are anodes. The cathode portions of the plurality of single-plate capacitor elements are stacked and fixed on the side lead frame 9 and are sequentially stacked and fixed, and at least one of the conductive adhesive layers 10 is connected to the cathode side lead frame. 8 is a schematic cross-sectional view of a multilayer solid electrolytic capacitor (also abbreviated as each layer-facing multilayer type) fixed on 8.
[0019]
  FIG.Show for referenceFIG. 2 is a schematic cross-sectional view showing an example of a layered solid electrolytic capacitor, in which a plurality of single-plate capacitor elements 7 having different lengths of the solid electrolyte layer 4 are densely and efficiently stacked within a limited exterior resin size. A multilayer solid electrolytic capacitor (also referred to as a close-packed multilayer capacitor for short) is shown.
[0020]
In the multilayer solid electrolytic capacitor of the present invention, the number of laminated single plate capacitor elements is the shape and thickness of the single plate capacitor element, the design or required performance of the thickness of the conductive adhesive layer, the laminated form (for example, Although depending on FIG. 4 to FIG. 8)), etc., usually 2 to 20, preferably 2 to 12, are used.
[0021]
  In the multilayer solid electrolytic capacitor, as shown in FIG. 1, a single-plate capacitor element 7 is provided with a taper-like gradient on the cathode portion and a thickness S of the tip portion of the cathode portion.₂Is the thickness S of the cathode base₁A larger single plate capacitor element is preferably used. When manufacturing a multilayer solid electrolytic capacitor using such a single plate capacitor element, as long as a plurality of single plate capacitor elements are placed in a limited chip volume,In FIG.The laminated structure shown is preferably used. NaThe negative anode lead frames 8 and 9 can be configured using, for example, a known iron-based or copper-based alloy material, plating material, or the like.
[0022]
The present invention is further described below.
In the present invention, when a multilayer capacitor element 19 is obtained by laminating a plurality of single-plate capacitor elements 7, a conductive adhesive layer (using a conductive paste) is used between each cathode part and between the cathode part and the cathode side lead frame 8. 10), and the connection between each anode part and between the anode part 11 and the anode side lead frame 9 is carried out by spot welding or laser welding.
In the case of the laminated structure as shown in FIG. 4 or FIG. 5, the plate-like valve metal in the portion having the solid electrolyte layer 4 of the single plate capacitor element 7 is laminated almost parallel to the cathode side lead frame 8. Therefore, the anode part 11 may be bent so that spot welding can be performed.
[0023]
On the other hand, in the case of the laminated structure as shown in FIGS. 6 to 8, the plurality of anode portions 11 of the single-plate capacitor element 7 are aligned in the same direction, and each anode portion 11 is close to the surface of the anode-side lead frame 9. By laminating in this manner, the thick cathode part is formed so as to be divergent from the anode part 11 side toward the cathode part side, thereby avoiding stress concentration when laminating on the lead frame. Particularly preferably, the single plate capacitor element has a divergent shape as shown in FIG. 1, so that the anode part 11 can be easily fixed (stacked and fixed) by spot welding or the like, and between the cathode parts and between the cathode part and the cathode side lead. It has been found that the laminated adhesion by the conductive adhesive layer 10 between the frames 8 is facilitated, and as a result, a multilayer capacitor element 19 having a high yield and excellent heat resistance is obtained. The conductive adhesive layer 10 can be formed using a conductive paste such as a silver paste containing silver fine powder.
[0024]
By the way, there is a known example (Japanese Patent Laid-Open No. 6-13269) in which two single-plate capacitor elements are mounted on a lead frame in a divergent shape, the purpose of which is to relieve the curing stress of the resin when sealed with an exterior resin. Therefore, the present invention is essentially different from the present invention in that it is intended to have a divergent shape and does not describe that the anode part is laminated and fixed to the surface of the lead frame.
[0025]
Further, in the present invention, since a large number of single-plate capacitor elements are built in a predetermined dimension of the exterior resin, when a single-plate capacitor element is laminated and fixed on the cathode-side lead frame with a conductive paste, an appropriate amount of conductive material is used. It is preferable to apply the paste to a specific range of the cathode portion and the lead frame, and further, a monolithic capacitor element is pressure-laminated with an appropriate pressure, so that a multilayer capacitor element having a divergent shape is easily obtained.
[0026]
That is, the applied pressure when the single plate capacitor element is laminated and fixed on the cathode side lead frame using the conductive paste is about 17 to 420 g / cm.²It is preferable that it is the range of these. Therefore, when the single plate capacitor element has a thickness of 0.3 mm, a width of 3 mm, and a length of 4 mm, a load of about 2 g to 50 g is applied when the single plate capacitor elements are laminated and fixed.
[0027]
Further, the single plate capacitor element has a cathode portion with a tapered gradient as shown in FIG. 1 so that the single plate capacitor element has a divergent shape, or the thickness of the cathode portion of the single plate capacitor element is shown in FIG. It was found that a multilayer capacitor element having a divergent shape can be obtained without difficulty by increasing the shape of the single plate capacitor element to be divergent as shown in FIG.
[0028]
Next, a single plate capacitor element for manufacturing a multilayer solid electrolytic capacitor will be described.
In the single-plate capacitor element of the present invention, as shown in FIGS. 1 to 3, the end portion of the anode substrate 1 made of a flat valve-acting metal having a dielectric oxide film layer 2 on the surface serves as an anode portion 11. The solid electrolyte layer 4 and the conductor layers 5 and 6 are sequentially formed on the dielectric oxide film layer 2 excluding the anode portion 11 to form a cathode portion.
Here, the dielectric oxide film layer 2 is formed on the surface of pores made of a valve metal etched as a dielectric layer having a large surface area. It can be composed of an oxide of a valve metal such as tantalum or its sintered body. Examples of the valve action metal used in the present invention include aluminum, tantalum, niobium, and titanium.
[0029]
In the present invention, the anode substrate 1 refers to the valve metal support, and when the dielectric oxide film layer 2 is formed on the surface thereof to produce a single plate capacitor element, one end thereof is referred to as the anode portion 11. . Further, before the dielectric oxide film layer 2 is formed, an etching process for increasing the surface area of the anode substrate 1 is performed to increase the capacity.
As shown in FIGS. 1-3, the anode part 11 and the cathode part of the single plate capacitor element are separated by an insulating layer 3, and the solid electrolyte layer 4 and the conductive layers 5 and 6 are formed in the cathode part. The insulating layer 3 may be provided in contact with the anode portion 11 so as to be provided (peripherally provided) to separate the anode portion 11 and the cathode portion. The insulating layer 3 is a layer for electrically insulating the cathode portion and the anode portion 11.
[0030]
The insulating layer 3 is an insulating material, for example, 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 an inorganic fine powder and a cellulose resin (JP-A-HEI 11-80596 publication) can be used, but the material is not limited. Specific examples include polyphenylsulfone (PPS), polyethersulfone (PES), cyanate ester resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, etc.), polyimide and their derivatives. Etc. Particularly preferred are polyimide, polyethersulfone, fluororesin and their precursors.
[0031]
The polyimide is a compound having an imide structure in the main chain, and is usually obtained by imidization by applying a solution obtained by dissolving a precursor polyamic acid in a solvent to a high temperature after coating. As described above, the material is not limited to the chemical structure of polyimide, but preferably has an average molecular weight of 1,000 to 1,000,000, more preferably 2000 to 200,000. A compound is used.
[0032]
The solid electrolyte layer 4 is formed by chemical oxidation or electrolytic oxidation or the like of an organic substance containing a conductive polymer or tetracyanoquinodimethane (TCNQ), or a metal oxide or other inorganic substance such as manganese dioxide or lead dioxide. May be.
The conductor layer 5 on the solid electrolyte layer 4 can be formed using a carbon paste, and the conductor layer 6 on the conductor layer 5 can be formed using a conductive paste such as a silver paste, but is limited to these materials or methods thereof. It is not a thing.
[0033]
In the present invention, as the conductive polymer used for forming the solid electrolyte layer 4, an intrinsic conductive polymer (Japanese Patent Laid-Open No. 1-169914) or a π-conjugated polyaniline (for example, Japanese Patent Laid-Open No. 61-239617). Gazette), polypyrrole of a hetero five-membered cyclic compound (for example, JP-A-61-240625), polythiophene derivative (for example, JP-A-2-15611) and polyisothianaphthene (for example, JP-A-62-2650). No. 118511) can be used in the present invention.
[0034]
That is, in order to form the solid electrolyte layer 4, a conductive heavy layer containing at least one chemical structure selected from the group consisting of the chemical structures of divalent groups of aniline, pyrrole, thiophene, isothianaphthene and substituted derivatives thereof. Coalescence can be used. In addition, a known conductive polymer, that is, a polymer containing a divalent chemical structure of benzene, p-phenylene vinylene, thienylene vinylene, naphtho [2,3-c] thiophene and substituted derivatives thereof is also a solid electrolyte. Can be used to form layer 4. These conductive polymers are used to form the solid electrolyte layer 4 as a conductive polymer composition containing a dopant. Furthermore, not only the addition of a dopant but also an organic or inorganic filler may be used in combination.
[0035]
When using a polymer of a polymerizable hetero five-membered cyclic compound such as pyrrole or thiophene (hereinafter referred to as a hetero five-membered cyclic compound), the anode foil was immersed in a lower alcohol / water solution of the hetero five-membered cyclic compound. Thereafter, a method of forming a conductive polymer on the anode foil by dipping in an aqueous solution in which an oxidizing agent and an electrolyte are dissolved to form a conductive polymer on the anode foil (Japanese Patent Laid-Open No. 5-175082), 3,4-ethylenedioxy-thiophene monomer And an oxidizing agent, preferably in the form of a solution, and separately or together applied to a dielectric oxide film of a metal foil (Japanese Patent Laid-Open No. 2-15611 and Japanese Patent Laid-Open No. 10-32145) Etc. are applicable in the present invention. Further, as disclosed in JP-A-10-32145, poly (3,4-ethylenedioxy-thiophene) doped with a specific organic sulfonic acid such as benzoquinonesulfonic acid or alicyclic sulfonic acid is used. It can also be used in the present invention.
Furthermore, in the single plate capacitor element and the multilayer solid electrolytic capacitor of the present invention, a polymer of a 3,4-ethylenedioxy-thiophene derivative represented by the following general formula (I) is preferably used as the solid electrolyte 4. Can be used.
[0036]
[Chemical 1]

However, in the above general formula (I), R¹And R²Are each independently a hydrogen atom, C₁~ C₆A linear or branched saturated or unsaturated hydrocarbon group, or C₁~ C₆Represents a substituent that is bonded to each other at an arbitrary position to form a cyclic structure of at least one or more 5- to 7-membered saturated hydrocarbon containing two oxygen elements. The cyclic structure includes those having a vinylene bond which may be substituted and those having a phenylene structure which may be substituted.
Similarly, a polymer containing a chemical structure of a divalent group of the following general formula (II) can also be suitably used for forming the solid electrolyte 4.
[0037]
[Chemical 2]

In the above general formula (II), R^Three, R^Four, R^FiveAnd R⁶Each independently represents a hydrogen atom, C₁~ C_TenLinear or branched saturated or unsaturated alkyl group, alkoxy group or alkyl ester group, halogen atom, nitro group, cyano group, primary, secondary or tertiary amino group, trifluoromethyl group, phenyl group And a monovalent group selected from the group consisting of a substituted phenyl group, or R^Three, R^Four, R^FiveAnd R⁶The hydrocarbon chains of the divalent group are bonded to each other at any position to form at least one or more 3- to 7-membered saturated or unsaturated hydrocarbon cyclic structures together with carbon atoms substituted by such groups. These groups may be formed.
[0038]
In the general formula (II), R^Three, R^Four, R^FiveAnd R⁶The alkyl group, alkoxy group, alkyl ester group represented by or a cyclic hydrocarbon chain formed by them may contain any number of carbonyl, ether, ester, amide, sulfide, sulfinyl, sulfonyl and imino bonds. Δ described in the general formula (II) represents the number of charges per repeating unit and is in the range of 0 to 1.
[0039]
However, in the single plate capacitor element and the multilayer solid electrolytic capacitor of the present invention, the chemical structure is not particularly limited, and the electric conductivity of the material forming the solid electrolyte 4 is usually in the range of 0.1 to 200 S / cm. Desirably, it may be in the range of 1 to 100 S / cm, more preferably in the range of 10 to 100 S / cm.
[0040]
As an oxidizing agent suitable for oxidative polymerization of a hetero five-membered cyclic compound such as pyrrole or thiophene, for example, iron (III) chloride, Fe (C10) described in JP-A-2-15611_Four)_ThreeAnd organic acid iron (IlI), inorganic acid iron (IlI), alkyl persulfate, ammonium persulfate, hydrogen peroxide and the like can be widely used. Examples of the organic acid of the organic acid iron (Ill) include alkyl sulfonic acids having 1 to 20 carbon atoms such as methanesulfonic acid and dodecylbenzenesulfonic acid, and also aliphatic carboxylic acids. However, the range of use of the oxidizing agent may be limited by the chemical structure of the monomer compound, the oxidizing agent, reaction conditions, and the like. For example, according to the description of Handbook of Conducting Polymers (published by Marcel Dekker, Inc., 1987, page 99, FIG. 5), the oxidation (polymerization) of thiophenes depends on the type of substituent (polymerization). Is a major measure of the likelihood of the occurrence of a.) And greatly affects the polymerization reaction (the oxidation potential broadly ranges from about 1.8 to about 2.7 V). Therefore, specifically, the combination of the monomer compound used, the oxidizing agent, and the reaction conditions is important.
[0041]
The dopant contained in the conductive polymer is not limited to a polymer having a π-electron conjugated structure to be used. The dopant may usually be an anion, and the anion may be a low molecular anion or a polymer anion such as a polymer electrolyte. For example, specifically, PF₆ ^-, SbF₆ ^-, AsF₆ ^-5B group element halide anions such as BF_Four ^-A halide anion of a group 3B element such as I^-(I_Three ^-), Br^-, Cl^-A halogen anion such as_Four ^-Perhalogenate anions such as AlCl_Four ^-  FeCl_Four ^-  SnCl_Five ^-Lewis acid anions such as NO or NO_Three ^-, SO_Four ^2-Inorganic acid anions such as p-toluenesulfonic acid or naphthalenesulfonic acid, C₁~ C_FiveAlkyl-substituted naphthalenesulfonic acid, CF_ThreeSO_Three ^-, CH_ThreeSO_Three ^-Organic sulfonate anions, such as_ThreeCOO^-, C₆H_FiveCOO^-And protonic acid anions such as carboxylic acid anions.
[0042]
More preferably, an organic sulfonate anion, an organic phosphate anion, or the like is used. In particular, the organic sulfonate anion includes an aromatic sulfonate anion, an aromatic polysulfonate anion, an organic sulfonate anion substituted with an OH group or a carboxy group, an aliphatic organic sulfonate anion having a skeleton such as adamantane, and the like. Various compounds are applicable.
[0043]
Examples of organic sulfonic acids include benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid, ethanesulfonic acid, α-sulfo-naphthalene, β-sulfo-naphthalene, naphthalene disulfonic acid, alkylnaphthalenesulfonic acid (alkyl) Examples of the group include butyl, triisopropyl, di-t-butyl and the like.
As other examples, an anion of a sulfoquinone compound having one or more sulfoanion groups and a quinone structure in the molecule (hereinafter abbreviated as sulfoquinone anion), anthracene sulfonate anion, naphthalene sulfonate anion, benzene sulfonate anion And xylylene disulfonate anion (o, p, m).
[0044]
As the basic skeleton of the sulfoquinone anion, p-benzoquinone, o-benzoquinone, 1,2-naphthoquinone, 1,4-naphthoquinone, 2,6-naphthoquinone, 9,10-anthraquinone, 1,4-anthraquinone, 1,2 -Anthraquinone, 1,4-chrysenequinone, 5,6-chrysenequinone, 6,12-chrysenequinone, acenaphthoquinone, acenaphthenequinone, carphorquinone, 2,3-bornanedione, 9,10-phenanthrenequinone, 2,7-pyrenequinone It is done.
[0045]
Among them, as the sulfoquinone used in the present invention, anthraquinone, 1,4-naphthoquinone, and sulfoquinone having a 2,6-naphthoquinone skeleton are preferably used. For example, in the case of anthraquinones, anthraquinone-1-sulfonic acid, anthraquinone-2-sulfonic acid, anthraquinone-1,5-disulfonic acid, anthraquinone-1,4-disulfonic acid, anthraquinone-1,3-disulfonic acid, anthraquinone-1 , 6-disulfonic acid, anthraquinone-1,7-disulfonic acid, anthraquinone-1,8-disulfonic acid, anthraquinone-2,6-disulfonic acid, anthraquinone-2,3-disulfonic acid, anthraquinone-2,7-disulfonic acid Anthraquinone-1,4,5-trisulfonic acid, anthraquinone-2,3,6,7-tetrasulfonic acid, alkali metal salts thereof, ammonium salts thereof and the like can be used.
[0046]
In the case of 1,4-naphthoquinones, 1,4-naphthoquinone-5-sulfonic acid, 1,4-naphthoquinone-6-sulfonic acid, 1,4-naphthoquinone-5,7-disulfonic acid, 1,4-naphthoquinone -5,8-disulfonic acid, alkali metal salts thereof, ammonium salts thereof and the like can be used.
In the case of 2,6-naphthoquinones, 2,6-naphthoquinone-1-sulfonic acid, 2,6-naphthoquinone-3-sulfonic acid, 2,6-naphthoquinone-4-sulfonic acid, 2,6-naphthoquinone-3 , 7-disulfonic acid, 2,6-naphthoquinone-4,8-disulfonic acid, alkali metal salts thereof, ammonium salts thereof and the like can be used.
[0047]
Further, examples of the sulfoquinone include industrial dyes such as anthraquinone iris R and anthraquinone violet RN-3RN, which can also be used in the form of the salt as a useful sulfoquinone dopant.
Furthermore, polyelectrolyte anions such as polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyvinyl sulfonic acid, polyvinyl sulfuric acid, poly-α-methyl sulfonic acid, polyethylene sulfonic acid, and polyphosphoric acid are also used.
[0048]
These dopants also include a reductant anion of a known oxidant that can produce the conductive polymer. For example, sulfate ions that are production anions of oxidizing agents such as alkali metal persulfates and ammonium persulfates can be mentioned. In addition, manganese such as potassium permanganate, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetrachloro-1,4-benzoquinone, tetracyano-1,4-benzoquinone And dopants produced from quinones such as
[0049]
As mentioned above, what contains at least 1 sort (s) of the said dopant in a conductive polymer is used suitably in this invention. For example, sulfate ion as a dopant in the conductive polymer is in the range of 0.01 to 10 mol% with respect to all repeating units of the π-conjugated structure, and the sulfoquinone anion such as anthraquinonesulfonate anion is 1 as the other dopant. The range of ˜50 mol% is included.
[0050]
On the other hand, the single plate capacitor element will be further described.
As shown in FIGS. 1 and 2, as a single-plate capacitor element, when a thick tip shape having a cathode portion tip portion thickness larger than the cathode portion base portion thickness is used, a laminated solid electrolytic capacitor is laminated. The multilayer capacitor element 19 tends to have a divergent shape. That is, as the shape of the single plate capacitor element 7, as shown in FIG. 1, the total thickness of the solid electrolyte layer 4 and the conductor layers 5 and 6 is gradually increased toward the tip of the cathode portion, or the thickness thereof. As shown in FIG. 2, a shape in which the thickness is increased stepwise toward the tip of the cathode portion is preferable.
As another embodiment of the present invention, in the thick single plate capacitor element, the cathode base thickness S₁And the maximum thickness S of the tip₂Ratio S to₂/ S₁Is in the range of 1.1 to 5.0, more preferably in the range of 1.3 to 3.0.
[0051]
As an example of a method for obtaining the single-plate capacitor element 7 having the shape shown in FIG. 1, there is a method of mechanically pressure-molding the conductive layers 5 and 6 on the front end side after applying the conductive paste so as to be thick. As another method, there is a method in which a conductive paste is repeatedly applied to the tip of the element 7 and the conductors 5 and 6 are thickened gradually or stepwise as shown in FIGS. The tip portion of the element 7 is the thickness S of the base portion of the cathode portion.₁Any method may be used as long as it can be made larger.
[0052]
For example, a single plate capacitor element may be laminated by using a conductive paste on a cathode-side lead frame, or a laminated product in which two or more sheets are laminated in a divergent shape in advance. The lead frame may be laminated by adhesion. Furthermore, these elements may be stacked and stacked. Other lamination methods may be employed. A single plate capacitor element may be laminated on one of the front and back sides of the lead frame (see, for example, FIG. 4) or on both sides of the front and back surfaces (see, for example, FIGS. 5, 6, and 8).
[0053]
A single-plate capacitor element may be laminated in a divergent shape using a single-plate capacitor element whose upper and lower surfaces are substantially parallel instead of a tip, and as a method of obtaining the multilayer capacitor element, the thickness of the conductive adhesive layer is There is a method of making it larger at the cathode portion tip side than at the cathode portion base side.
[0054]
The conductive adhesive layer between the cathode part and the cathode part and the conductive adhesive layer between the cathode part and the cathode-side lead frame are from the tip of the cathode part to 80% of the cathode part length L (see FIG. 1). Range (that is, length L from the tip of the cathode portion of the conductive adhesive layer)₁Is preferably 0.8 × L or less. If the conductive adhesive layer is formed beyond the range of 80% from the tip, the conductive paste may reach the anode during lamination, and leakage current will not occur even if the yield deteriorates due to a short circuit or does not become a short circuit. There is a risk of performance degradation such as an increase. In order to form the conductive adhesive layer in a range of up to 80% of the length L of the cathode portion, the conductive paste is preferably applied in a range from the tip side of the cathode portion length to a half length.
[0055]
Further, it is preferable that a plurality of single plate capacitor elements are mechanically pressure-laminated to form a multilayer capacitor element having a divergent shape. That is, when laminating a plurality of single-plate capacitor elements on the cathode-side lead frame with a conductive paste, the thickness of the conductive paste is adjusted by pressing the single-plate capacitor elements with a pressure plate with an appropriate pressure, so that a predetermined dimension is obtained. The shape is widened at the end.
[0056]
At this time, if the thickness of the conductive adhesive layer is gradually increased from the cathode base to the tip of the cathode, the thickness of the tip of the cathode of the multilayer capacitor element becomes larger than the thickness of the cathode base. As a result, the multilayer capacitor element tends to have a divergent shape. For example, as shown in FIG. 6 and FIG.₁And the maximum thickness W of the tip of the cathode portion of the element 19₂Ratio W with₂/ W₁Is preferably in the range of 1.3 to 5.5, more preferably in the range of 1.5 to 3.5.
The anode part of the single plate capacitor element may be bent after the lamination of the single plate capacitor elements, or may be bent in advance before the lamination.
[0057]
Any method such as spot welding, laser welding, or connection with a conductive paste may be adopted as a method for connecting the anode portion and the anode portion and between the anode portion and the anode side lead frame. The order of stacking the cathode portions and connecting the anode portions is not particularly limited, either may be first or may be alternately performed. In any case, it is important to produce a multilayer capacitor element by laminating so that no large mechanical stress is applied to the single-plate capacitor element 7.
[0058]
The multilayer capacitor element is sealed with an exterior resin, and a lead frame outside the exterior resin is bent along the exterior resin to form an external lead as a multilayer solid electrolytic capacitor. Examples of the exterior resin are epoxy resin, phenol resin, and the like, and the external lead can be made of, for example, a material (42 alloy).
If the anode part of a single plate capacitor element is aligned in the same direction and laminated and fixed on the anode side lead frame, or if a thick single plate capacitor element is used, the multilayer capacitor element can be prevented from protruding from the exterior resin, In addition, it is possible to obtain a high-capacity multilayer solid capacitor by increasing the number of laminated single-plate capacitor elements.
[0059]
In the present invention, it is possible to manufacture the capacitor chip size required by the rated specification by devising the laminated structure. For example, by applying the laminated structure of the present invention, the CV value per unit volume of the capacitor chip is 7.1 × 10.^ThreeVF / m^Three(Or 7.1 × 10^-3V · F / cm^ThreeEquivalent to the above), preferably 7.3 × 10^ThreeVF / m^ThreeMore preferably, 7.8 × 10^ThreeVF / m^ThreeThe above solid electrolytic capacitor can be provided.
For example, as a solid electrolytic capacitor with a rating of 6.3 V / 100 μF, the CV value per unit volume is 7.1 × 10 with a D case size (0.73 cm × 0.43 cm × height 0.29 cm).^ThreeVF / m^ThreeThe above solid electrolytic capacitor can be manufactured.
[0060]
【Example】
  The present invention will be described with reference to examples, but the present invention is not limited to these examples.
  In the following examples, Example 2, Example 4, and Example 5 are shown as reference examples.
Example 1: Manufacturing of a thick single-plate capacitor element An aluminum (valve action metal) etching foil (anode substrate 1) having a thickness of 90 μm, a length of 5 mm, and a width of 3 mm having a dielectric oxide film layer 2 of alumina on the surface. ) 2 mm length and 3 mm width portion is used as anode 11, and the remaining 3 mm × 3 mm portion is formed into 13V with 10 mass% ammonium adipate aqueous solution to form dielectric oxide film layer 2 at the cut end Then, a dielectric was prepared. The dielectric surface was impregnated with an aqueous solution prepared to 20% by mass of ammonium persulfate and 0.1% by mass of sodium anthraquinone-2-sulfonate, and then 5 g of 3,4-ethylenedioxy-thiophene was dissolved. . Soaked in 2 mol / l isopropanol solution. The substrate was taken out and left in an environment of 60 ° C. for 10 minutes to complete the oxidation polymerization and washed with water. Each of the polymerization reaction treatment and the washing step was repeated 10 times to form a conductive polymer solid electrolyte layer 4.
[0061]
Next, the conductive layer 5 was formed by being immersed in a carbon paste tank and solidified. Then, a thick single plate capacitor element 7 shown in FIG. 1 was obtained by repeatedly increasing the thickness of the conductor layer 6 toward the tip by repeating the operation of dipping in the silver paste tank and solidifying. Thickness S of the cathode base portion of the single plate capacitor element 7₁And the maximum thickness S of the tip₂Ratio S to₂/ S₁Was 2.1.
[0062]
Example 2
The multilayer capacitor element of this example is shown schematically in FIG. Three single-plate capacitor elements manufactured by the method of Example 1 were prepared, and as shown in FIG. 4, the three anode portions 11 were aligned to the left, the three cathode portions were aligned to the right, and the cathode The flat valve metal in the portion having a solid electrolyte layer with a conductive paste is laminated substantially parallel to the cathode side lead frame 8 between the cathode portion and the cathode portion and between the cathode portion and the lead frame 8. Thus, a multilayer capacitor element was obtained. The multilayer capacitor element shown in FIG. 4 was obtained by spot welding the anode portions 11 and one surface of the lead frame 9 and the lower surface of the anode portion 11 while bending the anode portion 11 of the multilayer product.
The coating length of the conductive paste was from the tip to 80% of the cathode portion length L.
[0063]
Example 3:
The multilayer capacitor element of this example is shown in FIG. Six single-plate capacitor elements manufactured by the method of Example 1 were prepared, and among these, three anode parts 11 were aligned on the left side, three cathode parts were aligned on the right side, A multilayer paste capacitor element having three layers was manufactured by bonding a conductive paste between the cathode part and between the cathode part and the lead frame 8. The coating length of the conductive paste was from the tip to 50% of the cathode portion length L. After producing two three-layer multilayer capacitor elements by the same method, these multilayer capacitor elements face each other like the structure of FIG. A multilayer capacitor manufactured with such a multilayer structure could be stacked more closely in a smaller and smaller volume.
[0064]
Example 4
The multilayer capacitor element of this example is shown schematically in FIG. Six single-plate capacitor elements manufactured by the method of Example 1 were prepared, and as shown in FIG. 7, three single-plate capacitor elements were laminated with the anode portions alternately facing each other as shown in FIG. did. After producing two such multilayer capacitor elements, these multilayer capacitors were sequentially laminated and fixed by forming conductive adhesive layers on the front and back of the cathode side lead frame. At this time, the anode portion is laminated and fixed on the anode side lead frame in the same direction by bending the anode portion as necessary, and the cathode portions of the plurality of single-plate capacitor elements are sequentially stacked and fixed by forming a conductive adhesive layer. . The coating length of the conductive paste was from the tip to 50% of the cathode portion length L.
[0065]
Example 5
The multilayer capacitor element of this example is shown schematically in FIG. Using the method of Example 1, three types of single-plate solid electrolytic capacitors having different lengths of two pairs of solid electrolyte layers were produced. As shown in FIG. 8, the single plate solid electrolytic capacitor having the shortest solid electrolyte layer is taken out, adhered to the lead frame 8 with a conductive paste, and the single plate solid electrolytic capacitor longer than the capacitor is placed thereon. The anode part 11 was aligned on the left side, the cathode part was aligned on the right side, and three sheets were sequentially laminated and fixed via a conductive adhesive layer between the cathode part and the cathode part. The same laminated structure was bonded to the back side of the lead frame 8, and a total of six single-plate solid electrolytic capacitors were placed on the front and back sides of the lead frame. The laminated capacitor element shown in FIG. 8 was manufactured by spot welding the anode parts 11 and the one surface of the lead frame 9 and the lower surface of the anode part 11 while bending the anode part 11 of the laminated product as necessary. . The coating length of the conductive paste was set to 50% of the cathode portion length L from the tip.
[0066]
Single plate solid electrolytic capacitors having different lengths of the solid electrolyte layer include an oxidizing agent bath (an aqueous solution composed of ammonium persulfate / sodium anthraquinone-2-sulfonate described in Example 1) and a solid electrolyte layer. This was achieved by controlling the immersion length in a monomer bath (3,4-ethylenedioxy-thiophene in isopropanol as described in Example 1).
[0067]
Example 6: Evaluation of capacitor characteristics
After manufacturing the multilayer capacitor having the multilayer structure described in Examples 2 to 5 as one evaluation unit for each 30 chips (n = 30), the characteristics were evaluated by the yield (%) and the leakage current after the reflow test. The results are summarized in Table 1.
[0068]
[Table 1]

[0069]
Example 7: Evaluation of a small-sized large-capacitance capacitor
As an example of evaluation of small size and large capacity, an 8-layered solid electrolytic capacitor was produced according to the method of Example 3. However, in the manufacture of this capacitor, it was produced with a D case size (0.73 cm × 0.43 cm × height 0.29 cm 2) rated 6.3 V. The CV value of the small-sized large-capacitance capacitor manufactured here was evaluated, and the results are shown in Table 2.
[0070]
[Table 2]

[0071]
【The invention's effect】
According to the laminated structure of the present invention, a small and large-capacity element can be manufactured. For example, as a solid electrolytic capacitor rated 6.3 V / 100 μF, the CV value per unit volume is 7.1 × in the D case size. 10^ThreeVF / m^ThreeThe above solid electrolytic capacitor can be easily manufactured. In addition, the multilayer structure of the present invention provides a multilayer capacitor element having excellent yield and heat resistance. In addition, the manufacturing cost of the capacitor can be significantly reduced by improving the yield.
[0072]
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of a single plate capacitor element used in the present invention.
FIG. 2 is a schematic cross-sectional view showing an example of a single plate capacitor element used in the present invention.
[Fig. 3]Shown as a reference example1 is a schematic cross-sectional view showing an example of a single plate capacitor element.
[Fig. 4]Shown as a reference example1 is a schematic cross-sectional view showing an example of a multilayer capacitor element.
[Figure 5]Shown as a reference example1 is a schematic cross-sectional view showing an example of a multilayer capacitor element.
FIG. 6 is a schematic cross-sectional view showing an example of the multilayer capacitor element of the present invention.
[Fig. 7]Shown as a reference example1 is a schematic cross-sectional view showing an example of a multilayer capacitor element.
[Fig. 8]Shown as a reference example1 is a schematic cross-sectional view showing an example of a multilayer capacitor element.
[0073]
[Explanation of symbols]
1 .... Anode substrate 2 .... Derivative oxide layer 3 .... Insulating layer 4 .... Solid electrolyte layer 5 .... Conductor layer (carbon paste layer) 6 .... Conductor layer (silver paste layer) , 7 .. Single plate capacitor element, 8 .. Cathode side lead frame, 9 .. Anode side lead frame, 10 .. Conductive adhesive layer, 11 .. Anode portion, 12 .. External lead, 13. , 14 .. Multilayer capacitor element, 15 .. Exterior resin, 16 .. Multilayer solid electrolytic capacitor

Claims (11)

An end of an anode substrate made of a flat valve action metal having a dielectric oxide film layer on the surface is used as an anode part, and a solid electrolyte layer is formed on the dielectric oxide film layer on the part excluding the anode part. A single plate capacitor element is composed of a cathode part in which a conductor layer is sequentially formed, and the cathode part of the single plate capacitor element has a shape spreading toward the tip of the cathode part from the anode part side. The anode part is laminated in a divergent shape from the anode part side toward the cathode part tip, and the anode part is laminated and fixed on the anode side lead frame to form a multilayer capacitor element. The cathode part of the conductor layer is bonded and fixed via a cathode side lead frame with the electrode part and the anode part being in different directions, and the cathode part joint surface of the two multilayer capacitor elements and the cathode side lead frame Stacked solid electrolytic capacitor beam and is characterized in that it is a parallel.   2. The multilayer capacitor element according to claim 1, wherein the lengths of the solid electrolytes of each single-plate capacitor element of one multilayer capacitor element and each single-plate capacitor element of the other multilayer capacitor element are not the same. Multilayer solid electrolytic capacitor.   3. The multilayer solid electrolytic capacitor according to claim 1, wherein the conductive adhesive layer is formed in a range from the tip of the cathode part to 80% of the length of the cathode part.   4. The multilayer solid electrolytic capacitor according to claim 1, wherein the multilayer capacitor element is obtained by pressure laminating a plurality of single plate capacitor elements.   A plurality of single-plate capacitor elements are bonded to each other between the cathode portion and the cathode portion and between the cathode portion and the cathode-side lead frame by a conductive adhesive layer. 5. The multilayer solid electrolytic capacitor according to claim 1, wherein the tip portion is larger than the cathode portion base side.   The multilayer solid electrolytic capacitor according to claim 1, wherein the solid electrolyte layer is formed using a conductive polymer.   The conductive polymer is a divalent group of a polymerizable hetero five-membered cyclic compound, aniline, benzene, p-phenylene vinylene, thienylene vinylene, isothianaphthene, naphtho [2,3-c] thiophene and substituted derivatives thereof. The multilayer solid electrolytic capacitor according to claim 6, which is a polymer containing at least one chemical structure selected from the group consisting of:   The multilayer solid electrolytic capacitor according to claim 7, wherein the polymerizable hetero five-membered cyclic compound is 3,4-ethylenedioxy-thiophene or a substituted derivative thereof.   The multilayer solid electrolytic capacitor according to any one of claims 1 to 8, wherein the plurality of single plate capacitor elements are in a range of 2 to 20.   10. The multilayer solid electrolytic capacitor according to claim 1, wherein means for aligning the anode parts in the same direction and stacking and fixing them on the anode side lead frame is spot welding. 11. The multilayer solid electrolytic capacitor according to claim 1, wherein a CV value per unit volume is 7.1 × 10 ³ V · F / m ³ or more.

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