JP3671828B2 - Manufacturing method of solid electrolytic capacitor - Google Patents
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- JP3671828B2 JP3671828B2 JP2000303351A JP2000303351A JP3671828B2 JP 3671828 B2 JP3671828 B2 JP 3671828B2 JP 2000303351 A JP2000303351 A JP 2000303351A JP 2000303351 A JP2000303351 A JP 2000303351A JP 3671828 B2 JP3671828 B2 JP 3671828B2
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【０００１】
【発明の属する技術分野】
本発明は、固体電解コンデンサの製造方法に関し、特に絶縁性高分子層を電解質の一部に配する耐電圧の優れた固体電解コンデンサの製造方法に関する。
【０００２】
【従来の技術】
近年、電気機器のデジタル化に伴って、コンデンサについても小型大容量で高周波領域でのインピーダンスの低いものが要求されている。そこで、コンデンサの電解質に電気伝導度の高い導電性高分子を用いて、高周波領域でのインピ−ダンスを低くしたコンデンサが多く提案されている。
【０００３】
特開平１−２５３２２６号公報には陽極酸化皮膜からなる誘電体層の上に導電性を有するマンガン酸化物層を形成し、マンガン酸化物層を経由して電解重合により導電性高分子層を形成してなる固体電解コンデンサが提案されている。
【０００４】
また、特開平２−１５６１１号公報には、陽極酸化皮膜からなる誘電体層の上に３、４ーエチレンジオキシチオフェンを繰り返し単位としｐ−トルエンスルホン酸アニオンをド−パントとして含む導電性高分子を化学重合により形成したコンデンサが提案されている。３，４−エチレンジオキシチオフェンモノマ−と酸化剤を溶媒により溶解した溶液を、酸化が施されたアルミニウム電極に塗布し、次いで室温あるいは加熱して溶媒を除去し、化学重合反応により導電性高分子層を形成し、次いで水を用いて導電性高分子層から過剰な酸化剤を洗い去り、最後に乾燥させてコンデンサを得る製造方法が記述されている。
【０００５】
また、特開平３−１８００９号公報には化学重合によるポリピロ−ル膜上に電解重合によるポリピロ−ル膜を形成するタンタル固体電解コンデンサの製造方法が提案されている。
【０００６】
また、特開平１０−２４７６１２号公報には導電性高分子を陰極導電層に用いて、漏れ電流の低い固体電解コンデンサを得ようとする方法として、陽極酸化皮膜からなる誘電体層の絶縁欠陥部に、かつ誘電体層と導電性高分子層の間に、電着法により絶縁性高分子層を形成し、実装時の熱応力による漏れ電流の増大を防止する方法が提案されている。
【０００７】
また、特開２０００−１３３５５６号公報には導電性高分子層を陰極導電層に用いた固体電解コンデンサにおいて、陽極酸化皮膜と導電性高分子層との間に絶縁層を設け、あるいは陽極酸化皮膜上に第一の導電性高分子層を形成した後に絶縁層を、さらにその上に第二の導電性高分子層を形成し、陽極酸化皮膜の表面に直接導電性高分子層あるいは第二の導電性高分子層が接触しないようにして漏れ電流を低減する方法が提案されている。
【０００８】
【発明が解決しようとする課題】
しかしながら、陽極酸化皮膜からなる誘電体層の絶縁欠陥部に、かつ誘電体層と導電性高分子層の間に、電着法により絶縁性高分子層を形成し、実装時の熱応力による漏れ電流の増大を防止する場合、絶縁性高分子層は絶縁欠陥部にしか形成されないために、実装時の熱応力により絶縁欠陥部周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止できず、また高い耐電圧特性が得られないという課題があった。
【０００９】
また、導電性高分子層を陰極導電層に用いた固体電解コンデンサにおいて、陽極酸化皮膜と導電性高分子層との間に絶縁層を設け、あるいは陽極酸化皮膜上に第一の導電性高分子層を形成した後に絶縁層を、さらにその上に第二の導電性高分子層を形成し、陽極酸化皮膜の表面に直接導電性高分子層あるいは第二の導電性高分子層が接触しないようにして漏れ電流を低減する場合、浸漬塗布や電解重合により陽極酸化皮膜あるいは第一の導電性高分子層の表面を絶縁層で完全に覆うために、良好な等価直列抵抗特性が得られないという課題があった。
【００１０】
本発明は、上記従来技術の課題を解決するもので、優れた等価直列抵抗特性と、低い漏れ電流特性、及び高い耐電圧特性を有する固体電解コンデンサの製造方法を提供することを目的としたものである。
【００１１】
【課題を解決するための手段】
本発明は上記の課題を解決するもので、本発明第一の固体電解コンデンサの製造方法は、陽極酸化皮膜からなる誘電体層を形成した弁金属電極を用意する工程と、前記誘電体層上にマンガン酸化物層を形成する工程と、前記マンガン酸化物層上の少なくとも一部に、前記誘電体層の絶縁欠陥部及びその周辺を覆う程度に電着により絶縁性高分子層を形成する工程と、前記マンガン酸化物層上あるいは絶縁性高分子層上に導電性高分子層を形成する工程とを備えた構成である。
【００１２】
導電性のあるマンガン酸化物層を介して電着を施すため、漏れ電流の流れる絶縁欠陥部及びその周辺を覆うように選択的に絶縁性高分子層を形成できるので、実装時や使用時の熱応力により絶縁欠陥部及びその周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止でき、かつ耐電圧特性の優れた固体電解コンデンサが得られる。また、マンガン酸化物層の全面を絶縁性高分子層が覆わないので、等価直列特性の優れた固体電解コンデンサが得られる。
【００１３】
本発明第二の固体電解コンデンサの製造方法は、陽極酸化皮膜からなる誘電体層を形成した弁金属電極を用意する工程と、前記誘電体層上に化学重合により第一の導電性高分子層を形成する工程と、前記第一の導電性高分子層上の少なくとも一部に、前記誘電体層の絶縁欠陥部及びその周辺を覆う程度に電着により絶縁性高分子層を形成する工程と、前記第一の導電性高分子層上あるいは絶縁性高分子層上に第二の導電性高分子層を形成する工程とを備えた構成である。
【００１４】
導電性のある第一の導電性高分子層を介して電着を施すため、漏れ電流の流れる絶縁欠陥部及びその周辺を覆うように選択的に絶縁性高分子層を形成できるので、実装時や使用時の熱応力により絶縁欠陥部及びその周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止でき、かつ耐電圧特性の優れた固体電解コンデンサが得られる。また、第一の導電性高分子層の全面を絶縁性高分子層が覆わないので、等価直列特性の優れた固体電解コンデンサが得られる。
【００１５】
本発明第三の固体電解コンデンサの製造方法は、陽極酸化皮膜からなる誘電体層を形成した弁金属電極を用意する工程と、可溶性導電性高分子が溶解された溶液組成物、または導電性高分子微粒子が分散媒中に分散された分散液状組成物からなる導電性組成物前駆体を用意する工程と、前記誘電体層上に前記導電性組成物前駆体を塗布する工程と、前記導電性組成物前駆体から媒体を除去して導電性組成物層を形成する工程と、前記導電性組成物層上の少なくとも一部に、前記誘電体層の絶縁欠陥部及びその周辺を覆う程度に電着により絶縁性高分子層を形成する工程と、前記導電性組成物層上あるいは絶縁性高分子層上に導電性高分子層を形成する工程とを備えた構成である。
【００１６】
導電性のある導電性組成物層を介して電着を施すため、漏れ電流の流れる絶縁欠陥部及びその周辺を覆うように選択的に絶縁性高分子層を形成できるので、実装時や使用時の熱応力により絶縁欠陥部及びその周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止でき、かつ耐電圧特性の優れた固体電解コンデンサが得られる。また、導電性組成物層の全面を絶縁性高分子層が覆わないので、等価直列特性の優れた固体電解コンデンサが得られる。
【００１７】
【発明の実施の形態】
本発明の請求項１記載の発明は、陽極酸化皮膜を有する誘電体層を形成した弁金属電極を用意する工程と、前記誘電体層上にマンガン酸化物層を形成する工程と、前記マンガン酸化物層上の少なくとも一部に、前記誘電体層の絶縁欠陥部及びその周辺を覆う程度に電着により絶縁性高分子層を形成する工程と、前記マンガン酸化物層上あるいは絶縁性高分子層上に導電性高分子層を形成する工程とを有する固体電解コンデンサの製造方法であり、導電性のあるマンガン酸化物層を介して電着を施すため、漏れ電流の流れる絶縁欠陥部及びその周辺を覆うように選択的に絶縁性高分子層を形成できるので、実装時や使用時の熱応力により絶縁欠陥部及びその周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止でき、かつ耐電圧特性の優れた固体電解コンデンサを実現できる。また、マンガン酸化物層の全面を絶縁性高分子層が覆わないので、等価直列特性の優れた固体電解コンデンサを実現できる。
【００１８】
ここで、弁金属として、アルミニウム、タンタル、ニオブ、チタン、ジルコニウムから選ばれる一種を用いることができる。
【００１９】
また、導電性高分子層は化学重合あるいは電解重合により形成することができる。重合性モノマ−として、ピロ−ル、チオフェン、アニリン、もしくはそれらの誘導体を用いることができる。
【００２０】
本発明の請求項２記載の発明は、陽極酸化皮膜を有する誘電体層を形成した弁金属電極を用意する工程と、前記誘電体層上に化学重合により第一の導電性高分子層を形成する工程と、前記第一の導電性高分子層上の少なくとも一部に、前記誘電体層の絶縁欠陥部及びその周辺を覆う程度に電着により絶縁性高分子層を形成する工程と、前記第一の導電性高分子層上あるいは絶縁性高分子層上に第二の導電性高分子層を形成する工程とを有する固体電解コンデンサの製造方法であり、導電性のある第一の導電性高分子層を介して電着を施すため、漏れ電流の流れる絶縁欠陥部及びその周辺を覆うように選択的に絶縁性高分子層を形成できるので、実装時や使用時の熱応力により絶縁欠陥部及びその周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止でき、かつ耐電圧特性の優れた固体電解コンデンサを実現できる。また、第一の導電性高分子層の全面を絶縁性高分子層が覆わないので、等価直列特性の優れた固体電解コンデンサを実現できる。
【００２１】
本発明の請求項３記載の発明は、陽極酸化皮膜を有する誘電体層を形成した弁金属電極を用意する工程と、可溶性導電性高分子が溶解された溶液組成物、または導電性高分子微粒子が分散媒中に分散された分散液状組成物を有する導電性組成物前駆体を用意する工程と、前記誘電体層上に前記導電性組成物前駆体を塗布する工程と、前記導電性組成物前駆体から媒体を除去して導電性組成物層を形成する工程と、前記導電性組成物層上の少なくとも一部に、前記誘電体層の絶縁欠陥部及びその周辺を覆う程度に電着により絶縁性高分子層を形成する工程と、前記導電性組成物層上あるいは絶縁性高分子層上に導電性高分子層を形成する工程とを有する固体電解コンデンサの製造方法であり、導電性のある導電性組成物層を介して電着を施すため、漏れ電流の流れる絶縁欠陥部及びその周辺を覆うように選択的に絶縁性高分子層を形成できるので、実装時や使用時の熱応力により絶縁欠陥部及びその周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止でき、かつ耐電圧特性の優れた固体電解コンデンサを実現できる。また、導電性組成物層の全面を絶縁性高分子層が覆わないので、等価直列特性の優れた固体電解コンデンサを実現できる。
【００２２】
ここで、可溶性導電性高分子溶液または導電性高分子微粒子分散液の製造方法が種々開示されており、それらを用いて容易に製造することができる。
【００２３】
例えば、ポリピロール類については、特開平６−２０６９８６号公報およびケミストリーオブマテリアル誌（アメリカンケミカルソサイアティ１９８９年発行）１巻６号６５０頁に記載されている方法で作製することができる。
【００２４】
例えばポリチオフェン類については、シンシテックメタルズ誌（エルゼビア発行）２６巻２６７頁およびシンシテックメタルズ誌（エルゼビア発行）８５巻１３９７頁に開示されている。
【００２５】
また例えばポリアニリン溶液の作製法については、米国特許５２３２６３１号公報およびシンシテックメタルズ誌（エルゼビア発行）８５巻１３３７頁に記載されている。また、ポリアニリン溶液は三菱レイヨン社より、アクアセーブという商品名で市販されている。
【００２６】
また、導電性組成物前駆体を塗布する方法としては浸漬塗布、刷毛塗り、スピンコ−ト、スプレ−塗布等が用いうる。
【００２７】
請求項４記載のように、導電性組成物前駆体にバインダ−を添加することにより、耐電圧特性をより向上させることができる。
【００２８】
ここで、バインダ−には媒体に分散する高分子や結着剤が用いうる。例えば、ポリビニルピロリドン、ポリビニルアルコ−ル、水溶性ポリエステル、水溶性アクリル樹脂、カルボキシメチルセルロ−ス、ポリビニルスルホン酸塩、ポリスチレンスルホン酸塩、アルコキシシラン等が上げられる。
【００２９】
請求項５記載のように、絶縁性高分子層がポリカルボン酸系樹脂、ポリイミド系樹脂またはポリアミン系樹脂のいずれかであることが好適である。
【００３０】
以下、本発明の各実施の形態について詳細に説明する。
【００３１】
（実施の形態１）
以下、本発明第１の実施の形態について図１をもとに説明する。同図（ａ）は本実施の形態におけるコンデンサ素子の外観図であり、（ｂ）は断面図である。
【００３２】
縦８ｍｍ×横３．３ｍｍのアルミニウムエッチド箔１を、４ｍｍと３ｍｍの部分に仕切るように、両面に渡って、幅１ｍｍのポリイミドテープ２を貼付けた。
【００３３】
次に、アルミニウムエッチド箔１の３ｍｍ×３．３ｍｍの部分に陽極リード線８を取り付け、アルミニウムエッチド箔１の４ｍｍ×３．３ｍｍの部分を、７０℃の３％アジピン酸アンモニウム水溶液を用い、まず１０ｍＶ／ｓの速度で０から３５Ｖまで上げ、続けて３５Ｖの定電圧を３０分間印加し、陽極酸化により誘電体層３を形成した。そして、脱イオン水の流水により１０分洗浄してから、１０５℃で５分乾燥を行った。この構成をコンデンサと見立て、化成液中の容量を測定したところ、５μＦであった。
【００３４】
３０％硝酸マンガン水溶液の中に、アルミニウムエッチド箔１の誘電体層３が設けられた部分を浸漬し、自然乾燥させた後２５０℃で３０分間加熱し熱分解処理を行い、誘電体層３上にマンガン酸化物層４を形成した。
【００３５】
次に、マンガン酸化物層４を介して絶縁欠陥部及びその周辺に電着によってポリカルボン酸系樹脂からなる絶縁性高分子層５を形成する。まず、用いた電着液組成は、固形分１０重量％、脱イオン水８６重量％、ブチルセロソルブ４重量％である。その中の固形分は、分子量約３万のアクリル酸とメタクリル酸とスチレンの共重合体とベンゾグアナミンを７対３で混合し、電着液中に分散させるため、カルボン酸基の５０％をトリメチルアミンにより中和したものを用いた。
【００３６】
この電着液にアルミニウムエッチド箔１のマンガン酸化物層４が設けられた部分を浸漬し、アルミニウムエッチド箔１が陽極側となるように、リ−ド線８と隔離して設けた電極との間に電圧１０Ｖを印加し、５分間定電圧電着を行った。
【００３７】
次に、脱イオン水による洗浄を２０分間行ってから、８０℃２０分間と１８０℃３０分間熱処理することにより、ベンゾグアナミンとの間で架橋反応させて、ポリカルボン酸系樹脂からなる絶縁性高分子層５を絶縁欠陥部及びその周辺を覆うように形成した。なお、ここでは、電着から熱処理までを２回繰り返して絶縁性高分子層５を形成した。
【００３８】
次に、ピロ−ルモノマ−０．２５ｍｏｌ／ｌとアニオン系界面活性剤であるアルキルナフタレンスルホン酸ナトリウム（平均分子量３３８）０．１ｍｏｌ／ｌを脱イオン水の中に入れ、スタ−ラで撹拌して分散させた電解液を用意する。電解液にアルミニウムエッチド箔１のマンガン酸化物層４が設けられた部分を浸漬し、不図示のステンレス製の電解重合用電極をマンガン酸化物層４に近接するようにポリイミドテ−プ２に接触させ、電解重合用電極と隔離して設けた不図示の電解重合用第二電極との間に３Ｖを３０分印加して、電解重合によりマンガン酸化物層４あるいは絶縁性高分子層５の上にポリピロ−ルからなる導電性高分子層６を形成した。
【００３９】
次に、脱イオン水の中にアルミニウムエッチド箔１を１０分浸漬して洗浄を行った。そして、オ−ブン中に入れて１０５℃で５分乾燥した。
【００４０】
導電性高分子層６形成の後、その上に、カ−ボン層と銀ペイント層で陰極層７を形成すると共に、陰極リ−ド線９を取り付けた。
【００４１】
さらに、エポキシ樹脂を用いて外装してから、エ−ジング処理を行い、合計で１０個のコンデンサを完成させた。
【００４２】
これら１０個のコンデンサについて、１ｋＨｚにおける容量、３００ｋＨｚにおける等価直列抵抗、２２０℃５分加熱前後の１０Ｖ印加したときの漏れ電流、及び１Ｖ刻みで順方向の電圧を印加して絶縁破壊が起こる電圧を各々測定した。それらの平均値を以下の（表１）に示した。
【００４３】
本実施の形態では、導電性のあるマンガン酸化物層を介して電着を施すため、漏れ電流の流れる絶縁欠陥部及びその周辺を覆うように選択的に絶縁性高分子層を形成できるので、実装時や使用時の熱応力により絶縁欠陥部及びその周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止でき、かつ耐電圧特性の優れた固体電解コンデンサを実現できることが分かった。また、マンガン酸化物層の全面を絶縁性高分子層が覆わないので、等価直列特性の優れた固体電解コンデンサを実現できることが分かった。
【００４４】
（実施の形態２）
ついで、本発明第２の実施の形態について説明する。
【００４５】
本実施の形態では、マンガン酸化物層に替えてポリ（３，４−エチレンジオキシチオフェン）（ＰＥＤＯＴ）からなる第一の導電性高分子層を用いた以外、実施の形態１と同様にして固体電解コンデンサを作製した。なお、実施の形態１のポリピロ−ルからなる導電性高分子層を、ここでは第二の導電性高分子層と名称を変更している。
【００４６】
第一の導電性高分子層の形成方法を説明する。まず、３，４−エチレンジオキシチオフェン（ＥＤＯＴ）１ｍｏｌ／ｌと酸化剤のナフタレンスルホン酸第二鉄０．２ｍｏｌ／ｌのメタノ−ルを溶媒とした混合溶液を用意した。
【００４７】
混合溶液の中にアルミニウムエッチド箔の誘電体層が設けられた部分を１分浸漬してから引き上げ、６０℃のオ−ブン中に入れて３０分放置した。化学重合反応により誘電体層の上にＰＥＤＯＴからなる第一の導電性高分子層を形成した後、有機溶剤のエタノ−ル中にアルミニウムエッチド箔を２０分浸漬して洗浄を行った。そして、オ−ブン中に入れて１０５℃で３０分乾燥した。
【００４８】
完成させたコンデンサについて実施の形態１と同様の評価を行い、その結果を前述の（表１）に示した。
【００４９】
本実施の形態では、導電性のある第一の導電性高分子層を介して電着を施すため、漏れ電流の流れる絶縁欠陥部及びその周辺を覆うように選択的に絶縁性高分子層を形成できるので、実装時や使用時の熱応力により絶縁欠陥部及びその周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止でき、かつ耐電圧特性の優れた固体電解コンデンサを実現できることが分かった。また、第一の導電性高分子層の全面を絶縁性高分子層が覆わないので、等価直列特性の優れた固体電解コンデンサを実現できることが分かった。
【００５０】
（比較例１）
比較のため、比較例１として、第一の導電性高分子層の上に電着によって絶縁性高分子層を設けない以外実施の形態２と同様にしてコンデンサを作製した。
【００５１】
完成させたコンデンサについて実施の形態１と同様の評価を行い、その結果を前述の（表１）に示した。
【００５２】
比較例１では、電着により絶縁性高分子層を設けないために、（表１）に示すように、初期の漏れ電流も大きく、熱応力により漏れ電流が増大し、また耐電圧特性が悪かった。
【００５３】
（比較例２）
比較のため、比較例２として、第一の導電性高分子層の上に電着によって絶縁性高分子層を設けず、誘電体層と第一の導電性高分子層の間に絶縁性高分子層を設けた以外、実施の形態２と同様にしてコンデンサを作製した。
【００５４】
完成させたコンデンサについて実施の形態１と同様の評価を行い、その結果を前述の（表１）に示した。
【００５５】
比較例２では、電着により誘電体層上に直に絶縁性高分子層を形成しており、絶縁性高分子層は絶縁欠陥部しか覆わないために、熱応力により絶縁欠陥部周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大が生じ、また耐電圧特性が悪かった。
【００５６】
この（表１）における比較例１、２と実施の形態２との比較から明らかなように、実施の形態２では、導電性のある第一の導電性高分子層を介して電着を施すために、優れた等価直列抵抗特性と、低い漏れ電流特性、及び高い耐電圧特性を有する固体電解コンデンサを得られたことが判明した。
【００５７】
（実施の形態３）
ついで、本発明第３の実施の形態について説明する。
【００５８】
本実施の形態では、マンガン酸化物層に替えてポリアニリンからなる導電性組成物層を用いた以外、実施の形態１と同様にして固体電解コンデンサを作製した。
【００５９】
導電性組成物層の形成方法を説明する。まず、シンシテックメタルズ誌（エルゼビア発行）８５巻１３３７頁に開示されている方法で、約５重量％の可溶性導電性高分子が溶解されたスルホン化ポリアニリン水溶液組成物からなる導電性組成物前駆体を用意した。アルミニウムエッチド箔の誘電体層が設けられた部分に、導電性組成物前駆体を塗布後、５０℃で６０分、さらに１５０℃で１０分加熱して媒体を除去し、ポリアニリンからなる導電性組成物層を形成した。
【００６０】
完成させたコンデンサについて実施の形態１と同様の評価を行い、その結果を前述の（表１）に示した。
【００６１】
本実施の形態では、導電性のある導電性組成物層を介して電着を施すため、漏れ電流の流れる絶縁欠陥部及びその周辺を覆うように選択的に絶縁性高分子層を形成できるので、実装時や使用時の熱応力により絶縁欠陥部及びその周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止でき、かつ耐電圧特性の優れた固体電解コンデンサを実現できることが分かった。また、導電性組成物層の全面を絶縁性高分子層が覆わないので、等価直列特性の優れた固体電解コンデンサを実現できることが分かった。
【００６２】
（比較例３）
比較のため、比較例３として、導電性組成物層の上に電着によって絶縁性高分子層を設けない以外実施の形態３と同様にしてコンデンサを作製した。
【００６３】
完成させたコンデンサについて実施の形態１と同様の評価を行い、その結果を前述の（表１）に示した。
【００６４】
比較例３では、電着により絶縁性高分子層を設けないために、（表１）に示すように、初期の漏れ電流も大きく、熱応力により漏れ電流が増大し、また耐電圧特性が悪かった。
【００６５】
この（表１）における比較例３と実施の形態３との比較から明らかなように、実施の形態３では、導電性のある導電性組成物層を介して電着を施すために、優れた等価直列抵抗特性と、低い漏れ電流特性、及び高い耐電圧特性を有する固体電解コンデンサを得られたことが判明した。
【００６６】
（実施の形態４）
以下、本発明第４の実施の形態について図２をもとに説明する。
【００６７】
厚さ０．１ｍｍの高倍率エッチドアルミニウム箔をアジピン酸アンモニウム３％水溶液に浸し、７０℃で８０Ｖを３０分間印加して陽極酸化皮膜を形成し、２．３×１５５ｍｍの寸法に切断後アルミニウムタブを介して陽極リード１２を取り付けたコンデンサ陽極箔１１を用意した。また、０．０５ｍｍの高倍率エッチドアルミニウムを２．３×１８０ｍｍの寸法に切断し、陰極リード１４を取り付けた陰極箔１３を用意した。
【００６８】
図２のように、両箔を２．５×２２０ｍｍのポリアミド不織布製セパレータ１５を介して捲回した後、終末部を粘着テープ１６で止めた。そして、アジピン酸アンモニウム３％水溶液に浸し、７０℃で７０Ｖを３０分間印加して、再度陽極酸化皮膜形成処理を行った。この捲回型アルミニウム電解コンデンサ素子の液中容量は、５５μＦであった。
【００６９】
次に、約０．４重量％のコロイド状ポリ（３，４−エチレンジオキシチオフェン）微粒子が含まれる水分散液状組成物を用意した。これは、Ｆ．Ｊｏｎａｓ他著シンシテックメタルズ誌（エルゼビア発行）８５巻１３９７頁に開示されている方法に準じて作製した。この水分散液状組成物に、バインダ−として約１０重量％の水溶性アクリル樹脂を添加して、導電性組成物前駆体を作製した。
【００７０】
次に、導電性組成物前駆体にコンデンサ素子を浸漬して塗布後、５０℃で６０分、さらに１３０℃で２０分加熱して媒体を除去し、ポリ（３，４−エチレンジオキシチオフェン）とアクリル樹脂からなる導電性組成物層を形成した。
【００７１】
次に、導電性組成物層を介して陽極箔１１の絶縁欠陥部及びその周辺に電着によってポリカルボン酸系樹脂からなる絶縁性高分子層を形成する。電着液組成は、固形分１０重量％、脱イオン水８６重量％、ブチルセロソルブ４重量％である。その中の固形分は、分子量約３万のアクリル酸とメタクリル酸とスチレンの共重合体とベンゾグアナミンを７対３で混合し、電着液中に分散させるため、カルボン酸基の５０％をトリメチルアミンにより中和したものを用いた。
【００７２】
この電着液にコンデンサ素子を浸漬し、陽極箔１１が陽極側となるように、陽極リ−ド１２と隔離して設けた電極との間に電圧１５Ｖを印加し、５分間定電圧電着を行った。
【００７３】
次に、脱イオン水による洗浄を２０分間行ってから、８０℃２０分間と１８０℃３０分間熱処理することにより、ベンゾグアナミンとの間で架橋反応させて、ポリカルボン酸系樹脂からなる絶縁性高分子層を陽極箔１１の絶縁欠陥部及びその周辺を覆うように形成した。なお、ここでは、電着から熱処理までを２回繰り返して絶縁性高分子層を形成した。
【００７４】
次に、ナフタレンスルホン酸第二鉄０．８ｍｏｌ／ｌと３，４−エチレンジオキシチオフェンモノマ−１．６ｍｏｌ／ｌをメタノ−ルの中に入れて混合した重合溶液にコンデンサ素子を浸漬して塗布後、５０℃で３０分、９０℃で３０分の熱処理と洗浄・乾燥を施し、ポリ（３，４−エチレンジオキシチオフェン）層からなる導電性高分子層を形成した。
【００７５】
次に、コンデンサ素子をアルミケ−スの中に封口ゴムを用いて組み立ててから、エ−ジング処理を行い、合計で１０個のコンデンサを完成させた。
【００７６】
これら１０個のコンデンサについて、１ｋＨｚにおける容量、３００ｋＨｚにおける等価直列抵抗、２２０℃５分加熱前後の２５Ｖ印加したときの漏れ電流、及び１Ｖ刻みで順方向の電圧を印加して絶縁破壊が起こる電圧を各々測定した。それらの平均値を前述の（表１）に示した。
【００７７】
本実施の形態では、導電性のある導電性組成物層を介して電着を施すため、漏れ電流の流れる陽極箔の絶縁欠陥部及びその周辺を覆うように選択的に絶縁性高分子層を形成できるので、実装時や使用時の熱応力により絶縁欠陥部及びその周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止でき、かつ耐電圧特性の優れた固体電解コンデンサを実現できることが分かった。また、陽極箔上の導電性組成物層の全面を絶縁性高分子層が覆わないので、等価直列特性の優れた固体電解コンデンサを実現できることが分かった。
【００７８】
（比較例４）
比較のため、比較例４として、導電性組成物層の上に電着によって絶縁性高分子層を設けない以外実施の形態４と同様にしてコンデンサを作製した。
【００７９】
完成させたコンデンサについて実施の形態４と同様の評価を行い、その結果を前述の（表１）に示した。
【００８０】
比較例４では、電着により絶縁性高分子層を設けないために、（表１）に示すように、初期の漏れ電流も大きく、熱応力により漏れ電流が増大し、また耐電圧特性が悪かった。
【００８１】
この（表１）における比較例４と実施の形態４との比較から明らかなように、実施の形態４では、導電性のある導電性組成物層を介して電着を施すために、優れた等価直列抵抗特性と、低い漏れ電流特性、及び高い耐電圧特性を有する固体電解コンデンサを得られたことが判明した。
【００８２】
なお、実施の形態では可溶性導電性高分子としてスルホン化ポリアニリンを、導電性高分子微粒子としてポリ（３，４−エチレンジオキシチオフェン）を用いたが、可溶性の、あるいは分散可能な導電性高分子であればそれ以外の材料も用いることもでき、本発明はその種類に限定されない。
【００８３】
また、実施の形態ではバインダ−として水溶性アクリル樹脂を用いたが、媒体に分散可能な高分子や結着剤であればそれ以外の材料も用いることもでき、本発明はその種類に限定されない。
【００８４】
また、実施の形態では導電性組成物前駆体を一回塗布する場合について述べたが、繰り返し塗布して導電性組成物層を形成することもできる。
【００８５】
また、実施の形態では、絶縁性高分子層として、ポリカルボン酸系樹脂を用いたが、本発明はポリイミド系樹脂、ポリアミン系樹脂などの電着により薄膜を形成できる高分子材料であれば用いることもでき、本発明はその種類に限定されない。
【００８６】
【発明の効果】
以上のように本発明によれば、導電性のあるマンガン酸化物層、第一の導電性高分子層、あるいは導電性組成物層を介して電着を施すため、漏れ電流の流れる陽極酸化皮膜の絶縁欠陥部及びその周辺を覆うように選択的に絶縁性高分子層を形成できるので、実装時や使用時の熱応力により絶縁欠陥部及びその周辺に生じる陽極酸化皮膜の損傷による漏れ電流の増大を防止でき、かつ耐電圧特性の優れた固体電解コンデンサを得ることができるという有利な効果が得られる。
【００８７】
また、陽極箔上の導電性組成物層の全面を絶縁性高分子層が覆わないので、等価直列特性の優れた固体電解コンデンサを得ることができるという有利な効果が得られる。
【００８８】
【表１】
【図面の簡単な説明】
【図１】本発明第１の実施の形態におけるコンデンサ素子を示す図
【図２】本発明第４の実施の形態におけるコンデンサ素子を示す図
【符号の説明】
１ アルミニウムエッチド箔
２ ポリイミドテープ
３ 誘電体層
４ マンガン酸化物層
５ 絶縁性高分子層
６ 導電性高分子層
７ 陰極層
８、９ リ−ド線
１１ 陽極箔
１２ 陽極リ−ド
１３ 陰極箔
１４ 陰極リ−ド
１５ セパレ−タ
１６ 粘着テ−プ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a solid electrolytic capacitor, and more particularly to a method for manufacturing a solid electrolytic capacitor having an excellent withstand voltage in which an insulating polymer layer is disposed on a part of an electrolyte.
[0002]
[Prior art]
In recent years, with the digitization of electric equipment, capacitors having a small size and a large capacity and a low impedance in a high frequency region are required. Therefore, many capacitors have been proposed in which a conductive polymer having a high electric conductivity is used as the electrolyte of the capacitor to reduce the impedance in the high frequency region.
[0003]
In JP-A-1-253226, a conductive manganese oxide layer is formed on a dielectric layer made of an anodized film, and a conductive polymer layer is formed by electrolytic polymerization via the manganese oxide layer. A solid electrolytic capacitor has been proposed.
[0004]
Japanese Patent Laid-Open No. 2-15611 discloses that a conductive layer containing 3,4-ethylenedioxythiophene as a repeating unit and p-toluenesulfonic acid anion as a dopant on a dielectric layer made of an anodized film. Capacitors in which molecules are formed by chemical polymerization have been proposed. A solution in which 3,4-ethylenedioxythiophene monomer and oxidant are dissolved in a solvent is applied to an oxidized aluminum electrode, and then the solvent is removed by heating at room temperature or by heating. A manufacturing method is described in which a molecular layer is formed, then excess oxidant is washed from the conductive polymer layer with water and finally dried to obtain a capacitor.
[0005]
JP-A-3-18009 proposes a method for producing a tantalum solid electrolytic capacitor in which a polypyrrole film is formed by electrolytic polymerization on a polypyrrole film by chemical polymerization.
[0006]
Japanese Patent Application Laid-Open No. 10-247612 discloses a method for obtaining a solid electrolytic capacitor having a low leakage current by using a conductive polymer as a cathode conductive layer, and insulating defects in a dielectric layer made of an anodized film. In addition, a method has been proposed in which an insulating polymer layer is formed by an electrodeposition method between a dielectric layer and a conductive polymer layer to prevent an increase in leakage current due to thermal stress during mounting.
[0007]
Japanese Patent Application Laid-Open No. 2000-133556 discloses a solid electrolytic capacitor using a conductive polymer layer as a cathode conductive layer, an insulating layer provided between the anodized film and the conductive polymer layer, or an anodized film. The first conductive polymer layer is formed on the insulating layer, and the second conductive polymer layer is further formed thereon. The conductive polymer layer or the second conductive polymer layer is directly formed on the surface of the anodized film. There has been proposed a method for reducing a leakage current by preventing a conductive polymer layer from contacting.
[0008]
[Problems to be solved by the invention]
However, an insulating polymer layer is formed by an electrodeposition method at the insulation defect portion of the dielectric layer made of an anodized film and between the dielectric layer and the conductive polymer layer, and leakage due to thermal stress during mounting When preventing an increase in current, the insulating polymer layer is formed only in the insulation defect part, so it is not possible to prevent an increase in leakage current due to damage of the anodic oxide film around the insulation defect part due to thermal stress during mounting. In addition, there is a problem that high withstand voltage characteristics cannot be obtained.
[0009]
In the solid electrolytic capacitor using the conductive polymer layer as the cathode conductive layer, an insulating layer is provided between the anodized film and the conductive polymer layer, or the first conductive polymer is formed on the anodized film. After forming the layer, an insulating layer is formed, and a second conductive polymer layer is further formed thereon, so that the conductive polymer layer or the second conductive polymer layer is not in direct contact with the surface of the anodized film. Therefore, when the leakage current is reduced, the surface of the anodic oxide film or the first conductive polymer layer is completely covered with an insulating layer by dip coating or electrolytic polymerization, so that a good equivalent series resistance characteristic cannot be obtained. There was a problem.
[0010]
SUMMARY OF THE INVENTION The present invention solves the above-described problems of the prior art, and aims to provide a method for manufacturing a solid electrolytic capacitor having excellent equivalent series resistance characteristics, low leakage current characteristics, and high withstand voltage characteristics. It is.
[0011]
[Means for Solving the Problems]
The present invention solves the above problems, and the first method for producing a solid electrolytic capacitor according to the present invention comprises a step of preparing a valve metal electrode on which a dielectric layer made of an anodized film is formed; A step of forming a manganese oxide layer, and covering at least a part of the manganese oxide layer with an insulating defect portion of the dielectric layer and its periphery degree And a step of forming an insulating polymer layer by electrodeposition and a step of forming a conductive polymer layer on the manganese oxide layer or on the insulating polymer layer.
[0012]
Since electrodeposition is performed through a conductive manganese oxide layer, an insulating polymer layer can be selectively formed so as to cover the insulating defect portion where leakage current flows and its periphery, so that it can be used during mounting and use. It is possible to prevent an increase in leakage current due to damage of the anodized film generated in and around the insulation defect due to thermal stress, and a solid electrolytic capacitor having excellent withstand voltage characteristics can be obtained. In addition, since the insulating polymer layer does not cover the entire surface of the manganese oxide layer, a solid electrolytic capacitor having excellent equivalent series characteristics can be obtained.
[0013]
The method for producing a second solid electrolytic capacitor of the present invention comprises a step of preparing a valve metal electrode on which a dielectric layer made of an anodized film is formed, and a first conductive polymer layer by chemical polymerization on the dielectric layer. And covering at least a part of the first conductive polymer layer with an insulating defect portion of the dielectric layer and its periphery. degree And a step of forming an insulating polymer layer by electrodeposition and a step of forming a second conductive polymer layer on the first conductive polymer layer or on the insulating polymer layer. It is.
[0014]
Since electrodeposition is performed via the first conductive polymer layer that has conductivity, an insulating polymer layer can be selectively formed so as to cover the insulating defect portion where leakage current flows and its surroundings. In addition, it is possible to prevent an increase in leakage current due to damage of the anodized film formed in and around the insulation defect due to thermal stress during use, and a solid electrolytic capacitor having excellent withstand voltage characteristics can be obtained. In addition, since the insulating polymer layer does not cover the entire surface of the first conductive polymer layer, a solid electrolytic capacitor having excellent equivalent series characteristics can be obtained.
[0015]
The third method for producing a solid electrolytic capacitor of the present invention includes a step of preparing a valve metal electrode having a dielectric layer formed of an anodized film, a solution composition in which a soluble conductive polymer is dissolved, or a conductive high A step of preparing a conductive composition precursor comprising a dispersed liquid composition in which molecular fine particles are dispersed in a dispersion medium, a step of applying the conductive composition precursor on the dielectric layer, and the conductivity Removing the medium from the composition precursor to form a conductive composition layer, and covering at least a part of the conductive composition layer with an insulating defect portion of the dielectric layer and its periphery degree And a step of forming an insulating polymer layer by electrodeposition, and a step of forming a conductive polymer layer on the conductive composition layer or the insulating polymer layer.
[0016]
Since electrodeposition is performed through a conductive composition layer that has conductivity, an insulating polymer layer can be selectively formed so as to cover the insulating defect portion where leakage current flows and its periphery, so that it can be mounted and used. Thus, it is possible to prevent an increase in leakage current due to the damage of the anodized film formed in and around the insulation defect due to the thermal stress of the solid electrolytic capacitor, and to obtain a solid electrolytic capacitor having excellent withstand voltage characteristics. Further, since the insulating polymer layer does not cover the entire surface of the conductive composition layer, a solid electrolytic capacitor having excellent equivalent series characteristics can be obtained.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention includes a step of preparing a valve metal electrode in which a dielectric layer having an anodized film is formed, a step of forming a manganese oxide layer on the dielectric layer, and the manganese oxidation Covering at least a part of the physical layer with an insulation defect of the dielectric layer and its periphery degree A method for producing a solid electrolytic capacitor comprising: a step of forming an insulating polymer layer by electrodeposition; and a step of forming a conductive polymer layer on the manganese oxide layer or the insulating polymer layer, Since electrodeposition is performed through a conductive manganese oxide layer, an insulating polymer layer can be selectively formed so as to cover the insulating defect portion where leakage current flows and its periphery, so that it can be used during mounting and use. It is possible to prevent an increase in leakage current due to damage to the anodized film generated in and around the insulation defect due to thermal stress, and to realize a solid electrolytic capacitor having excellent withstand voltage characteristics. In addition, since the insulating polymer layer does not cover the entire surface of the manganese oxide layer, a solid electrolytic capacitor having excellent equivalent series characteristics can be realized.
[0018]
Here, as the valve metal, one selected from aluminum, tantalum, niobium, titanium, and zirconium can be used.
[0019]
The conductive polymer layer can be formed by chemical polymerization or electrolytic polymerization. As the polymerizable monomer, pyrrole, thiophene, aniline, or a derivative thereof can be used.
[0020]
According to a second aspect of the present invention, there is provided a step of preparing a valve metal electrode on which a dielectric layer having an anodized film is formed, and forming a first conductive polymer layer on the dielectric layer by chemical polymerization And covering at least part of the first conductive polymer layer with an insulating defect portion of the dielectric layer and its periphery. degree A solid electrolytic process comprising: forming an insulating polymer layer by electrodeposition; and forming a second conductive polymer layer on the first conductive polymer layer or the insulating polymer layer. In this method of manufacturing a capacitor, electrodeposition is performed through a conductive first conductive polymer layer, so that an insulating polymer layer is selectively covered so as to cover an insulating defect portion where leakage current flows and its periphery. Therefore, it is possible to prevent an increase in leakage current due to damage of the anodized film and its surroundings caused by thermal stress during mounting and use, and to realize a solid electrolytic capacitor having excellent withstand voltage characteristics. In addition, since the insulating polymer layer does not cover the entire surface of the first conductive polymer layer, a solid electrolytic capacitor having excellent equivalent series characteristics can be realized.
[0021]
The invention according to claim 3 of the present invention includes a step of preparing a valve metal electrode on which a dielectric layer having an anodized film is formed, a solution composition in which a soluble conductive polymer is dissolved, or conductive polymer fine particles Preparing a conductive composition precursor having a dispersed liquid composition dispersed in a dispersion medium, applying the conductive composition precursor on the dielectric layer, and the conductive composition Removing the medium from the precursor to form a conductive composition layer, and covering at least a part of the conductive composition layer with an insulating defect portion of the dielectric layer and its periphery; degree A method for producing a solid electrolytic capacitor comprising: a step of forming an insulating polymer layer by electrodeposition; and a step of forming a conductive polymer layer on the conductive composition layer or the insulating polymer layer. In addition, since the electrodeposition is performed through the conductive composition layer having conductivity, the insulating polymer layer can be selectively formed so as to cover the insulating defect portion where leakage current flows and its periphery, so that it can be used during mounting or use. It is possible to prevent an increase in leakage current due to damage of the anodized film generated in and around the insulation defect due to thermal stress, and to realize a solid electrolytic capacitor having excellent withstand voltage characteristics. Further, since the insulating polymer layer does not cover the entire surface of the conductive composition layer, a solid electrolytic capacitor having excellent equivalent series characteristics can be realized.
[0022]
Here, various methods for producing a soluble conductive polymer solution or a conductive polymer fine particle dispersion are disclosed, and they can be easily manufactured using them.
[0023]
For example, polypyrroles can be produced by the methods described in JP-A-6-206986 and Chemistry of Materials (American Chemical Society, 1989) Vol. 1, No. 6, page 650.
[0024]
For example, polythiophenes are disclosed in Syncitec Metals (issued by Elsevier), Vol. 26, page 267 and Syncitec Metals magazine (issued by Elsevier), Vol. 85, page 1397.
[0025]
Further, for example, a method for preparing a polyaniline solution is described in US Pat. No. 5,232,631 and Syncitec Metals (issued by Elsevier), Vol. 85, page 1337. The polyaniline solution is commercially available from Mitsubishi Rayon under the trade name Aqua Save.
[0026]
As a method for applying the conductive composition precursor, dip coating, brush coating, spin coating, spray coating, or the like can be used.
[0027]
As described in claim 4, the withstand voltage characteristic can be further improved by adding a binder to the conductive composition precursor.
[0028]
Here, a polymer or a binder dispersed in a medium can be used for the binder. Examples thereof include polyvinyl pyrrolidone, polyvinyl alcohol, water-soluble polyester, water-soluble acrylic resin, carboxymethyl cellulose, polyvinyl sulfonate, polystyrene sulfonate, and alkoxysilane.
[0029]
It is preferable that the insulating polymer layer is any one of a polycarboxylic acid resin, a polyimide resin, or a polyamine resin.
[0030]
Hereinafter, each embodiment of the present invention will be described in detail.
[0031]
(Embodiment 1)
Hereinafter, a first embodiment of the present invention will be described with reference to FIG. FIG. 4A is an external view of the capacitor element according to the present embodiment, and FIG.
[0032]
A polyimide tape 2 having a width of 1 mm was pasted on both sides so that an aluminum etched foil 1 having a length of 8 mm × width of 3.3 mm was divided into 4 mm and 3 mm portions.
[0033]
Next, the anode lead wire 8 is attached to the 3 mm × 3.3 mm portion of the aluminum etched foil 1, and the 4 mm × 3.3 mm portion of the aluminum etched foil 1 is used with a 3% ammonium adipate aqueous solution at 70 ° C. First, the voltage was increased from 0 to 35 V at a speed of 10 mV / s, and then a constant voltage of 35 V was applied for 30 minutes, and the dielectric layer 3 was formed by anodic oxidation. Then, after washing with running deionized water for 10 minutes, drying was performed at 105 ° C. for 5 minutes. This configuration was regarded as a capacitor, and the capacity in the chemical conversion solution was measured and found to be 5 μF.
[0034]
The portion of the aluminum etched foil 1 where the dielectric layer 3 is provided is immersed in a 30% aqueous manganese nitrate solution, air-dried, and then heated at 250 ° C. for 30 minutes for thermal decomposition treatment. A manganese oxide layer 4 was formed thereon.
[0035]
Next, an insulating polymer layer 5 made of a polycarboxylic acid resin is formed by electrodeposition on and around the insulating defect portion through the manganese oxide layer 4. First, the composition of electrodeposition used was 10% by weight of solid content, 86% by weight of deionized water, and 4% by weight of butyl cellosolve. The solid content is a mixture of acrylic acid, methacrylic acid and styrene copolymer having a molecular weight of about 30,000 and benzoguanamine in a ratio of 7 to 3, and 50% of the carboxylic acid groups are trimethylamine dispersed in the electrodeposition solution. What was neutralized by using was used.
[0036]
An electrode provided separately from the lead wire 8 so that the portion of the aluminum etched foil 1 provided with the manganese oxide layer 4 is immersed in this electrodeposition solution so that the aluminum etched foil 1 is on the anode side. A voltage of 10 V was applied between the electrodes and constant voltage electrodeposition was performed for 5 minutes.
[0037]
Next, after performing washing with deionized water for 20 minutes, a heat treatment at 80 ° C. for 20 minutes and 180 ° C. for 30 minutes is performed to cause a crosslinking reaction with benzoguanamine, thereby insulating polymer made of polycarboxylic acid resin. The layer 5 was formed so as to cover the insulation defect portion and its periphery. Here, the insulating polymer layer 5 was formed by repeating twice from electrodeposition to heat treatment.
[0038]
Next, 0.25 mol / l of pyrrole monomer and 0.1 mol / l of an alkyl surfactant sodium alkylnaphthalene sulfonate (average molecular weight 338) are put into deionized water and stirred with a stirrer. Prepare a dispersed electrolyte solution. The portion of the aluminum etched foil 1 where the manganese oxide layer 4 is provided is immersed in the electrolytic solution, and a not-shown stainless steel electrolytic polymerization electrode is placed on the polyimide tape 2 so as to be close to the manganese oxide layer 4. 3 V is applied for 30 minutes between a second electrode for electropolymerization (not shown) provided in contact with and separated from the electrode for electropolymerization, and the manganese oxide layer 4 or the insulating polymer layer 5 is formed by electropolymerization. A conductive polymer layer 6 made of polypyrrole was formed thereon.
[0039]
Next, the aluminum etched foil 1 was immersed in deionized water for 10 minutes for cleaning. And it put in the oven and dried at 105 degreeC for 5 minutes.
[0040]
After the formation of the conductive polymer layer 6, a cathode layer 7 was formed thereon with a carbon layer and a silver paint layer, and a cathode lead wire 9 was attached thereto.
[0041]
Further, after packaging with an epoxy resin, an aging treatment was performed to complete a total of 10 capacitors.
[0042]
For these 10 capacitors, the capacitance at 1 kHz, the equivalent series resistance at 300 kHz, the leakage current when 10 V is applied before and after heating at 220 ° C. for 5 minutes, and the voltage at which dielectric breakdown occurs by applying a forward voltage in 1 V increments. Each was measured. Their average values are shown in the following (Table 1).
[0043]
In the present embodiment, since the electrodeposition is performed through the conductive manganese oxide layer, the insulating polymer layer can be selectively formed so as to cover the insulating defect portion where leakage current flows and its periphery. It was found that an increase in leakage current due to damage of the anodized film in and around the insulation defect portion due to thermal stress during mounting and use can be prevented, and a solid electrolytic capacitor having excellent withstand voltage characteristics can be realized. It was also found that a solid electrolytic capacitor with excellent equivalent series characteristics can be realized because the insulating polymer layer does not cover the entire surface of the manganese oxide layer.
[0044]
(Embodiment 2)
Next, a second embodiment of the present invention will be described.
[0045]
In this embodiment, the first conductive polymer layer made of poly (3,4-ethylenedioxythiophene) (PEDOT) is used instead of the manganese oxide layer, and the same as in the first embodiment. A solid electrolytic capacitor was produced. Note that the name of the conductive polymer layer made of the polypyrrole of Embodiment 1 is changed here as the second conductive polymer layer.
[0046]
A method for forming the first conductive polymer layer will be described. First, a mixed solution was prepared using methanol of 3,4-ethylenedioxythiophene (EDOT) 1 mol / l and an oxidizing agent, naphthalenesulfonic acid ferric iron 0.2 mol / l, as a solvent.
[0047]
The portion where the dielectric layer of the aluminum etched foil was provided in the mixed solution was dipped for 1 minute, then pulled up, placed in an oven at 60 ° C., and left for 30 minutes. After the first conductive polymer layer made of PEDOT was formed on the dielectric layer by chemical polymerization reaction, the aluminum etched foil was immersed in an organic solvent ethanol for 20 minutes for cleaning. And it put in the oven and dried at 105 degreeC for 30 minutes.
[0048]
The completed capacitor was evaluated in the same manner as in the first embodiment, and the results are shown in Table 1 above.
[0049]
In this embodiment, since the electrodeposition is performed through the conductive first conductive polymer layer, the insulating polymer layer is selectively formed so as to cover the insulating defect portion where leakage current flows and its periphery. Since it can be formed, it can be seen that it is possible to prevent an increase in leakage current due to damage of the anodized film in and around the insulation defect due to thermal stress during mounting and use, and to realize a solid electrolytic capacitor with excellent withstand voltage characteristics. It was. Further, it was found that since the insulating polymer layer does not cover the entire surface of the first conductive polymer layer, a solid electrolytic capacitor having excellent equivalent series characteristics can be realized.
[0050]
(Comparative Example 1)
For comparison, as Comparative Example 1, a capacitor was fabricated in the same manner as in Embodiment 2 except that the insulating polymer layer was not provided by electrodeposition on the first conductive polymer layer.
[0051]
The completed capacitor was evaluated in the same manner as in the first embodiment, and the results are shown in Table 1 above.
[0052]
In Comparative Example 1, since the insulating polymer layer is not provided by electrodeposition, the initial leakage current is large as shown in (Table 1), the leakage current increases due to thermal stress, and the withstand voltage characteristics are poor. It was.
[0053]
(Comparative Example 2)
For comparison, as Comparative Example 2, an insulating polymer layer is not provided by electrodeposition on the first conductive polymer layer, and an insulating high layer is provided between the dielectric layer and the first conductive polymer layer. A capacitor was fabricated in the same manner as in Embodiment 2 except that a molecular layer was provided.
[0054]
The completed capacitor was evaluated in the same manner as in the first embodiment, and the results are shown in Table 1 above.
[0055]
In Comparative Example 2, the insulating polymer layer is formed directly on the dielectric layer by electrodeposition, and since the insulating polymer layer covers only the insulating defect portion, it is generated around the insulating defect portion due to thermal stress. The leakage current increased due to the damage of the anodized film, and the withstand voltage characteristics were poor.
[0056]
As is apparent from the comparison between Comparative Examples 1 and 2 in this (Table 1) and the second embodiment, in the second embodiment, electrodeposition is performed through the first conductive polymer layer having conductivity. Therefore, it was found that a solid electrolytic capacitor having excellent equivalent series resistance characteristics, low leakage current characteristics, and high withstand voltage characteristics was obtained.
[0057]
(Embodiment 3)
Next, a third embodiment of the present invention will be described.
[0058]
In the present embodiment, a solid electrolytic capacitor was produced in the same manner as in the first embodiment except that a conductive composition layer made of polyaniline was used instead of the manganese oxide layer.
[0059]
A method for forming the conductive composition layer will be described. First, a conductive composition precursor comprising a sulfonated polyaniline aqueous solution composition in which about 5% by weight of a soluble conductive polymer is dissolved by the method disclosed in Syncitech Metals (issued by Elsevier), Vol. 85, page 1337. Prepared. After applying the conductive composition precursor to the portion of the aluminum etched foil provided with the dielectric layer, the medium is removed by heating at 50 ° C. for 60 minutes and then at 150 ° C. for 10 minutes to form a conductive material comprising polyaniline. A composition layer was formed.
[0060]
The completed capacitor was evaluated in the same manner as in the first embodiment, and the results are shown in Table 1 above.
[0061]
In this embodiment, since the electrodeposition is performed through the conductive composition layer having conductivity, the insulating polymer layer can be selectively formed so as to cover the insulating defect portion where leakage current flows and its periphery. It was found that an increase in leakage current due to damage to the anodized film and its surroundings caused by thermal stress during mounting and use can be prevented, and a solid electrolytic capacitor having excellent withstand voltage characteristics can be realized. It was also found that a solid electrolytic capacitor with excellent equivalent series characteristics can be realized because the insulating polymer layer does not cover the entire surface of the conductive composition layer.
[0062]
(Comparative Example 3)
For comparison, as Comparative Example 3, a capacitor was produced in the same manner as in Embodiment 3 except that the insulating polymer layer was not provided by electrodeposition on the conductive composition layer.
[0063]
The completed capacitor was evaluated in the same manner as in the first embodiment, and the results are shown in Table 1 above.
[0064]
In Comparative Example 3, since the insulating polymer layer is not provided by electrodeposition, the initial leakage current is large as shown in (Table 1), the leakage current increases due to thermal stress, and the withstand voltage characteristics are poor. It was.
[0065]
As is apparent from the comparison between Comparative Example 3 and Embodiment 3 in Table 1, in Embodiment 3, the electrodeposition is performed through the conductive composition layer having conductivity, and thus excellent. It was found that a solid electrolytic capacitor having equivalent series resistance characteristics, low leakage current characteristics, and high withstand voltage characteristics was obtained.
[0066]
(Embodiment 4)
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG.
[0067]
A high-magnification etched aluminum foil with a thickness of 0.1 mm is immersed in a 3% aqueous solution of ammonium adipate, and an anodic oxide film is formed by applying 80 V at 70 ° C. for 30 minutes, and then cut to a size of 2.3 × 155 mm. Capacitor anode foil 11 with anode lead 12 attached via a tab was prepared. Moreover, 0.05 mm high-etched etched aluminum was cut into a size of 2.3 × 180 mm, and a cathode foil 13 to which a cathode lead 14 was attached was prepared.
[0068]
As shown in FIG. 2, both foils were wound through a 2.5 × 220 mm polyamide nonwoven fabric separator 15, and then the end portion was stopped with an adhesive tape 16. And it immersed in 3% ammonium adipate aqueous solution, 70V was applied for 30 minutes at 70 degreeC, and the anodic oxide film formation process was performed again. The volume of the wound aluminum electrolytic capacitor element in liquid was 55 μF.
[0069]
Next, an aqueous dispersion liquid composition containing about 0.4% by weight of colloidal poly (3,4-ethylenedioxythiophene) fine particles was prepared. This is because F.A. It was produced in accordance with the method disclosed in Jonas et al., Shincitec Metals magazine (issued by Elsevier), vol. About 10% by weight of a water-soluble acrylic resin as a binder was added to the water-dispersed liquid composition to prepare a conductive composition precursor.
[0070]
Next, after immersing the capacitor element in the conductive composition precursor and coating it, the medium is removed by heating at 50 ° C. for 60 minutes and further at 130 ° C. for 20 minutes to remove poly (3,4-ethylenedioxythiophene). And a conductive composition layer made of an acrylic resin.
[0071]
Next, an insulating polymer layer made of a polycarboxylic acid resin is formed by electrodeposition on and around the insulating defect portion of the anode foil 11 through the conductive composition layer. The electrodeposition liquid composition has a solid content of 10% by weight, 86% by weight of deionized water, and 4% by weight of butyl cellosolve. The solid content is a mixture of acrylic acid, methacrylic acid and styrene copolymer having a molecular weight of about 30,000 and benzoguanamine in a ratio of 7 to 3, and 50% of the carboxylic acid groups are trimethylamine dispersed in the electrodeposition solution. What was neutralized by using was used.
[0072]
A capacitor element is immersed in this electrodeposition solution, and a voltage of 15 V is applied between the anode lead 12 and the electrode provided separately so that the anode foil 11 is on the anode side, and constant voltage electrodeposition is performed for 5 minutes. Went.
[0073]
Next, after performing washing with deionized water for 20 minutes, a heat treatment at 80 ° C. for 20 minutes and 180 ° C. for 30 minutes is performed to cause a crosslinking reaction with benzoguanamine, thereby insulating polymer made of polycarboxylic acid resin. The layer was formed so as to cover the insulation defect portion of the anode foil 11 and its periphery. Here, the insulating polymer layer was formed by repeating twice from electrodeposition to heat treatment.
[0074]
Next, the capacitor element was immersed in a polymerization solution in which 0.8 mol / l of ferric naphthalene sulfonate and 1.6 mol / l of 3,4-ethylenedioxythiophene monomer were mixed in methanol. After coating, heat treatment and washing / drying were performed at 50 ° C. for 30 minutes and 90 ° C. for 30 minutes to form a conductive polymer layer composed of a poly (3,4-ethylenedioxythiophene) layer.
[0075]
Next, the capacitor element was assembled in an aluminum case using a sealing rubber, and then an aging treatment was performed to complete a total of 10 capacitors.
[0076]
For these 10 capacitors, the capacitance at 1 kHz, the equivalent series resistance at 300 kHz, the leakage current when applying 25 V before and after heating at 220 ° C. for 5 minutes, and the voltage at which dielectric breakdown occurs by applying a forward voltage in 1 V increments. Each was measured. Their average values are shown in Table 1 above.
[0077]
In this embodiment, since the electrodeposition is performed through the conductive composition layer having conductivity, the insulating polymer layer is selectively formed so as to cover the insulating defect portion of the anode foil in which the leakage current flows and its periphery. Since it can be formed, it can be seen that it is possible to prevent an increase in leakage current due to damage of the anodized film in and around the insulation defect due to thermal stress during mounting and use, and to realize a solid electrolytic capacitor with excellent withstand voltage characteristics. It was. It was also found that a solid electrolytic capacitor having excellent equivalent series characteristics can be realized because the insulating polymer layer does not cover the entire surface of the conductive composition layer on the anode foil.
[0078]
(Comparative Example 4)
For comparison, as Comparative Example 4, a capacitor was produced in the same manner as in Embodiment 4 except that the insulating polymer layer was not provided by electrodeposition on the conductive composition layer.
[0079]
The completed capacitor was evaluated in the same manner as in Embodiment 4, and the results are shown in Table 1 above.
[0080]
In Comparative Example 4, since the insulating polymer layer is not provided by electrodeposition, as shown in Table 1, the initial leakage current is large, the leakage current increases due to thermal stress, and the withstand voltage characteristics are poor. It was.
[0081]
As is clear from the comparison between Comparative Example 4 and Embodiment 4 in Table 1, in Embodiment 4, the electrodeposition is performed through the conductive composition layer having conductivity, and therefore excellent. It was found that a solid electrolytic capacitor having equivalent series resistance characteristics, low leakage current characteristics, and high withstand voltage characteristics was obtained.
[0082]
In the embodiment, sulfonated polyaniline is used as the soluble conductive polymer and poly (3,4-ethylenedioxythiophene) is used as the conductive polymer fine particles. However, the conductive polymer is soluble or dispersible. Any other material can be used, and the present invention is not limited to that type.
[0083]
In the embodiment, the water-soluble acrylic resin is used as the binder, but other materials can be used as long as the polymer or the binder can be dispersed in the medium, and the present invention is not limited to the type. .
[0084]
In the embodiment, the case where the conductive composition precursor is applied once has been described. However, the conductive composition layer can be formed by repeatedly applying the conductive composition precursor.
[0085]
In the embodiment, a polycarboxylic acid resin is used as the insulating polymer layer. However, the present invention uses a polymer material that can form a thin film by electrodeposition such as a polyimide resin and a polyamine resin. The present invention is not limited to that type.
[0086]
【The invention's effect】
As described above, according to the present invention, since the electrodeposition is performed through the conductive manganese oxide layer, the first conductive polymer layer, or the conductive composition layer, an anodic oxide film in which a leakage current flows. Insulating polymer layer can be selectively formed so as to cover the insulation defect part and its periphery, so that leakage current due to damage of the anodic oxide film in and around the insulation defect part due to thermal stress during mounting or use An advantageous effect is obtained that a solid electrolytic capacitor that can prevent the increase and has an excellent withstand voltage characteristic can be obtained.
[0087]
Moreover, since the insulating polymer layer does not cover the entire surface of the conductive composition layer on the anode foil, an advantageous effect that a solid electrolytic capacitor having excellent equivalent series characteristics can be obtained.
[0088]
[Table 1]
[Brief description of the drawings]
FIG. 1 is a diagram showing a capacitor element according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a capacitor element according to a fourth embodiment of the present invention.
[Explanation of symbols]
1 Aluminum etched foil
2 Polyimide tape
3 Dielectric layer
4 Manganese oxide layer
5 Insulating polymer layer
6 Conductive polymer layer
7 Cathode layer
8,9 Lead wire
11 Anode foil
12 Anode lead
13 Cathode foil
14 Cathode lead
15 Separator
16 Adhesive tape
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000303351A JP3671828B2 (en) | 2000-10-03 | 2000-10-03 | Manufacturing method of solid electrolytic capacitor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000303351A JP3671828B2 (en) | 2000-10-03 | 2000-10-03 | Manufacturing method of solid electrolytic capacitor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2002110468A JP2002110468A (en) | 2002-04-12 |
| JP3671828B2 true JP3671828B2 (en) | 2005-07-13 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000303351A Expired - Fee Related JP3671828B2 (en) | 2000-10-03 | 2000-10-03 | Manufacturing method of solid electrolytic capacitor |
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| JP (1) | JP3671828B2 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007189199A (en) * | 2005-12-12 | 2007-07-26 | Tdk Corp | Capacitor and method of manufacturing same |
| JP2013062531A (en) * | 2005-12-12 | 2013-04-04 | Tdk Corp | Capacitor and manufacturing method of the same |
| JP4868234B2 (en) * | 2006-12-26 | 2012-02-01 | Ｔｄｋ株式会社 | Capacitor manufacturing method |
| US9564270B2 (en) | 2013-12-27 | 2017-02-07 | Tdk Corporation | Thin film capacitor |
| JP6446877B2 (en) | 2014-07-16 | 2019-01-09 | Tdk株式会社 | Thin film capacitor |
| JP6365216B2 (en) | 2014-10-15 | 2018-08-01 | Tdk株式会社 | Thin film capacitor |
| JP6266555B2 (en) * | 2015-03-18 | 2018-01-24 | 伸和コントロールズ株式会社 | Electrodeposition coating method, heat transfer tube manufacturing method, and heat exchanger manufacturing method |
| JP6641872B2 (en) | 2015-10-15 | 2020-02-05 | Tdk株式会社 | Electronic device sheet |
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| JP2002110468A (en) | 2002-04-12 |
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