JP4260443B2 - Capacitor powder, sintered body using the same, and capacitor using the same - Google Patents

Description

（式（１）および（２）において，Ｒ¹〜Ｒ⁴は水素、炭素数１〜６のアルキル基または炭素数１〜６のアルコキシ基を表し、これらは互いに同一であっても相違してもよく、Ｘは酸素、イオウまたは窒素原子を表し、Ｒ⁵はＸが窒素原子のときのみ存在して水素または炭素数１〜６のアルキル基を表し、Ｒ¹とＲ²およびＲ³とＲ⁴は互いに結合して環状になっていても良い。）で表される繰り返し単位を２以上含む重合体にドーパントをドープした電導性高分子を主成分とした有機半導体からなる群より選ばれた少なくとも一種の有機半導体である前項９乃至１１のいずれか１項に記載のコンデンサ。
（１３）有機半導体が、ポリピロール、ポリチオフェンおよびこれらの置換誘導体から選ばれた少なくとも一種である前項１２に記載のコンデンサ。
（１４）電導性高分子が、下記一般式（３）
【化４】

（式中、Ｒ⁶及びＲ⁷は、各々独立して水素原子、炭素数１乃至６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、または該アルキル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わす。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。）で示される繰り返し単位を含む電導性高分子である前項１２に記載のコンデンサ。
（１５）電導性高分子が、ポリ（３，４−エチレンジオキシチオフェン）にドーパントをドープした電導性高分子である前項１４に記載のコンデンサ。
【００１０】
【発明の実施の形態】
本発明のコンデンサ用粉体を得る一形態を説明する。
【００１１】
本発明に使用される土酸金属の代表例として、タンタル、ニオブ、タンタルニオブ合金及びこれらを主成分とする合金があげられる。これら土酸金属を主成分とする粉体は、一般に入手できるものを用いることができる。たとえば、ハロゲン化土酸金属のマグネシウムやナトリウムによる還元、フッ化土酸金属酸カリウムのナトリウム還元、フッ化土酸金属酸カリウムのニッケル陰極上への溶融塩（ＮａＣｌ＋ＫＣｌ）電解、土酸金属の五酸化物のアルカリ金属、アルカリ土類金属、カーボンまたは水素による還元、土酸金属インゴットへの水素導入後の粉砕・脱水素等によって得ることができる。
【００１２】
前記土酸金属に含有されるリンの出発材料として、酸化リン、窒化リン、炭化リン、硫化リン，珪素化リン、リン化金属（銅、銀、白金、チタン、バナジン、クロム、マンガン、鉄などの金属とリンとの化合物）、リン酸塩、及び下記一般式（４）、（５）、（６）、及び（７）で代表される化合物及びこれらの塩からなる群より選ばれる少なくとも一種を使用することができる。
【００１３】
【化５】

【００１４】
【化６】

【００１５】
【化７】

【００１６】
【化８】

【００１７】
（一般式（４）〜（７）で、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵は、それぞれ独立に、水素、水酸基、炭素数６以下のアルキル基、炭素数６以下のアルコシキ基、アリール基およびハロゲンから選ばれた一種を表す。また、一般式（４）乃至（７）で表される化合物のＲ¹を除く部分をＲ^Xとすると、Ｒ¹、Ｒ²は、それぞれ独立に、Ｒ^XまたはＯ−Ｒ^Xであってもよい。すなわち、一般式（４）乃至（７）で表される化合物は、リン−リン結合またはリン−酸素−リン結合を有するリン化合物の多量体であってもよい。）
【００１８】
一般式（４）乃至（７）で表される化合物の例として、例えば、ハロゲン化リン、トリアルコキシリン、リン酸トリアルコキシ、６フッ化リン酸アンモニウム塩、ポリリン酸がある。
【００１９】
土酸金属に含有されたリンの含有量は、３質量ｐｐｂ〜１質量ｐｐｍ、好ましくは、１０質量ｐｐｂ〜１質量ｐｐｍの範囲である。この範囲外にあると本発明の効果は、期待できない。
【００２０】
リン化合物を前記土酸金属に含有させる方法として、土酸金属粉体にリン化合物を所定量混合させるか、土酸金属粉体を作製する時の原料または中間体にリン化合物を所定量混合させるか、或いは土酸金属がインゴットの場合は、インゴット作製段階にリン化合物を所定量混合させて（インゴット作製時のリンの飛散質量を予備実験で吟味しておいて）、いわゆるリン−土酸金属合金インゴットとしておく方法があげられる。
【００２１】
リンが含有した土酸金属を主成分とする粉体の平均粒径は、０．１μｍ以上で５μｍ未満、好ましくは０．２μｍ以上で２μｍ未満である。平均粒径が５μｍ以上であると、作製した焼結体自身のＣＶ値が小さく、容量の大きなコンデンサを作製することが困難であるため好ましくない。０．１μｍ未満であると、本発明を持ってしても他方の電極材料を含浸することが難しく、かえって容量を下げるため好ましくない。該平均粒径範囲にある本発明の粉体の比表面積は、０．５〜１５ｍ²／ｇである。本発明のコンデンサ用粉体は、該粉体を所定の大きさに造粒して使用しても良い。
造粒方法として、従来公知の方法が採用できる。例えば、粉体を５００℃〜２０００℃の高温真空下に放置した後、湿式または乾式解砕する方法、アクリル樹脂やポリビニルアルコール等の適当なバインダーと粉体を混合した後解砕する方法、アクリル樹脂や樟脳等の適当な化合物と混合した後高温真空下に放置し、その後湿式または乾式解砕する方法等があげられる。造粒と解砕の程度によって造粒粉の粒径は、任意に変更可能であるが、通常、平均粒径で１０μｍ〜３００μｍのものが使用される。造粒・解砕後に分級して用いても良い。また、造粒後に造粒前の粉体を適量混合して用いても良い。
【００２２】
本発明のコンデンサ用粉体（造粒した粉体をも含む）は、一部窒化した粉体であることが好ましい。窒化量は、数１０質量ｐｐｍ〜数万質量ｐｐｍである。該粉体から焼結体を作製し、後記するように該焼結体の表面に誘電体を形成して、酢酸水溶液中でＬＣ値を測定した場合、小さいＬＣ値とするには、前記窒化量は、３００〜７０００質量ｐｐｍにすることが好ましい。ここで窒化量とは、粉体に吸着したものではなく、反応して窒化したものである。
【００２３】
粉体の窒化は、液体窒化、イオン窒化、ガス窒化などのうちいずれかあるいはそれらの組み合わせた方法で実施することができる。窒素ガス雰囲気によるガス窒化処理は、装置が簡便で操作が容易なため好ましい。たとえば窒素ガス雰囲気によるガス窒化方法は、前記粉体を窒素雰囲気中に放置することによって達成される。窒化する雰囲気温度は、２０００℃以下、放置時間は、数時間以内で目的とする窒化量の粉体が得られる。高温で処理することにより処理時間を短くすることができる。前記粉体の窒化量は、被窒化物の窒化温度と窒化時間を予備実験等で確認した条件で管理することができる。
【００２４】
造粒粉体を窒化する場合、窒化した未造粒粉体から造粒粉体を作製してさらに窒化処理を行っても良い。
【００２５】
本発明の焼結体は、前述した粉体を焼結して製造する。焼結体の製造方法の１例を以下に示す。なお、焼結体の製造方法は、この例に限定されるものではない。例えば、粉体を所定の形状に加圧成型した後、１０^-1〜１０^-4Ｐａで、数分〜数時間、５００〜２０００℃で加熱して得られる。このような焼結体の比表面積は、通常、０．２〜７ｍ²／ｇになる。
【００２６】
また、適当な形状・長さの、ニオブやタンタル等の弁作用金属からなるリードワイヤーを用意し、前述した粉体の加圧成型時に該リードワイヤーの一部が成型体の内部に挿入されるように一体成型して、該リードワイヤーを前記焼結体の引き出しリードとなるように設計することもできる。
【００２７】
前述した焼結体を一方の電極とし他方の電極の間に介在した誘電体とからコンデンサを製造することができる。コンデンサの誘電体として酸化ニオブおよび酸化タンタルを主成分とする誘電体があげられる。例えば、酸化ニオブを主成分とする誘電体は、一方の電極であるニオブ焼結体を電解液中で化成することによって得られる。ニオブ電極を電解液中で化成するには、通常プロトン酸水溶液、例えば、０． １％酢酸水溶液または硫酸水溶液を用いて行われる。ニオブ電極を電解液中で化成して酸化ニオブを主成分とする誘電体を得る場合。本発明のコンデンサは、電解コンデンサとなり、ニオブ側が陽極となる。
【００２８】
一方、本発明のコンデンサの他方の電極として、有機半導体および無機半導体から選ばれた少なくとも１種の化合物があげられる。有機半導体の具体例としては、ベンゾピロリン４量体とクロラニルからなる有機半導体、テトラチオテトラセンを主成分とする有機半導体、テトラシアノキノジメタンを主成分とする有機半導体、下記一般式（１）または（２）で表される繰り返し単位を含む高分子にドーパントをドープした電導性高分子を主成分とした有機半導体があげられる。
【００２９】
【化９】

【００３０】
式（１）および（２）において，Ｒ¹〜Ｒ⁴は水素、炭素数１〜６のアルキル基または炭素数１〜６のアルコキシ基を表し、これらは互いに同一であっても相違してもよく、Ｘは酸素、イオウまたは窒素原子を表し、Ｒ⁵はＸが窒素原子のときのみ存在して水素または炭素数１〜６のアルキル基を表し、Ｒ¹とＲ²およびＲ³とＲ⁴は互いに結合して環状になっていても良い。
【００３１】
さらに、本発明においては、前記一般式（１）で表される繰り返し単位を含む電導性高分子は、好ましくは下記一般式（３）で示される構造単位を繰り返し単位として含む電導性高分子が挙げられる。
【００３２】
【化１０】

【００３３】
式中、Ｒ⁶及びＲ⁷は、各々独立して水素原子、炭素数１乃至６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、または該アルキル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わす。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。このような化学構造を含む電導性高分子は、荷電されており、ドーパントがドープされる。ドーパントには公知のドーパントが制限なく使用できる。
【００３４】
式（１）乃至（３）で表される繰り返し単位を含む高分子としては、例えば、ポリアニリン、ポリオキシフェニレン、ポリフェニレンサルファイド、ポリチオフェン、ポリフラン、ポリピロール、ポリメチルピロール、およびこれらの置換誘導体や共重合体などが挙げられる。中でもポリピロール、ポリチオフェン及びこれらの置換誘導体（例えばポリ（３，４−エチレンジオキシチオフェン）等）が好ましい。
【００３５】
無機半導体の具体例としては。二酸化鉛または二酸化マンガンを主成分とする無機半導体、四三酸化鉄からなる無機半導体などがあげられる。このような半導体は、単独でも、または、２種以上組み合わせて使用しても良い。
【００３６】
上記有機半導体および無機半導体として、電導度１０^-2〜１０³Ｓ／ｃｍの範囲のものを使用すると、作製したコンデンサのインピーダンス値がより小さくなり、高周波での容量をさらに一層大きくすることができる。
【００３７】
さらに他方の電極が固体の場合には、その上に外部引き出しリード（例えば、リードフレーム）との電気的接触をよくするために、導電体層を設けてもよい。
【００３８】
導電体層としては、例えば、導電ペーストの固化、メッキ、金属蒸着、耐熱性の導電樹脂フイルムの形成等により形成することができる。導電ペーストとしては、銀ペースト、銅ペースト、アルミペースト、カーボンペースト、ニッケルペースト等が好ましいが、これらは１種を用いても２種以上を用いてもよい。２種以上を用いる場合、混合してもよく、または別々の層として重ねてもよい。導電ペーストを適用した後、空気中に放置するか、または加熱して固化せしめる。メッキとしては、ニッケルメッキ、銅メッキ、銀メッキ、アルミメッキ等があげられる。また蒸着金属としては、アルミニウム、ニッケル、銅、銀等があげられる。
【００３９】
具体的には、例えば他方の電極上にカーボンペースト、銀ペーストを順次積層しエポキシ樹脂のような材料で封止してコンデンサが構成される。このコンデンサは、前記焼結体と一体に焼結成型された、または後で溶接されたニオブまたはタンタルリードを有していてもよい。
【００４０】
以上のような構成の本発明のコンデンサは、例えば、樹脂モールド、樹脂ケース、金属性の外装ケース、樹脂のディッピング、ラミネートフイルムによる外装などの外装により各種用途のコンデンサ製品とすることができる。
【００４１】
【実施例】
以下、本発明の具体例についてさらに詳細に説明する。
【００４２】
本発明の粉体に含有されている微量なリン量は、本出願人によって開発された、フローインジェクション／ＩＣＰ−ＭＳシステムによる方法で測定した。フローインジェクションシステムは、ペリスタックポンプ（東京理科機械（株）製ＭＰ−３２）、ポリテトラフルオロエチレン製バルブ（レオダイン社製５０２０および５０１１）、陰イオン交換カラムアッセンブリー（ポリテトラフルオロエチレン管に強塩基性イオン交換樹脂＜室町化学製Ｄｏｗｅｘ１−Ｘ８ ５０〜１００メッシュを充填）、ポリテトラフルオロエチレン製メンブランフィルタ（日本ミリポア工業製ＦＧ 孔径０．２μｍ、面積４．０ｃｍ²）、及びポリテトラフルオロエチレン管（接続管内径０．８ｍｍ、反応管２．０ｍｍ）からなり、前述したＩＣＰ−ＭＳ（セイコーインスツルメント製ＳＰＱ８０００）とメンブランフィルター部とポリテトラフルオロエチレンチューブを用いて接続されている。尚、前記システムは、クラス１０００のクリーンルームに設置した。 また、粉体の窒化量は、ＬＥＫＯ社製の窒素・酸素分析計を用いて求めた。焼結体のＣＶ値は、０．１％酢酸水溶液中で２０Ｖ印加、８０℃、２００分化成した後に、３０％硫酸中で測定した容量と、化成電圧２０Ｖとの積から求めた。また、容量出現率は、前記した条件で１０００分化成したときの３０％硫酸中での容量を１００％として、コンデンサ形成後の容量との比で表現した。コンデンサの耐湿値は、作製したコンデンサを、６０℃９５％ＲＨで５００時間放置したときの容量が、初期値の１２０％を超える個数で表現した。この個数が小さいほど耐湿値は良好となる。ＣＶ値、容量出現率および耐湿値を求めるための試料数は、各例とも３０個とした。
実施例１〜５、比較例１〜３
平均粒径０．８μｍ（比表面積３．８ｃｍ²／ｇ）のニオブ粉に、別途用意したトリエトキシリンを、各々、所定量加えリン量が表１に記載の含有量となるように調整した。ついで各例の粉体を、１２００℃で真空加熱した後取り出し、解砕後分級し平均粒径９０μｍの造粒粉（比表面積１．３ｃｍ²／ｇ）とした。この造粒粉から、各例とも１．８×３．５×４．５ｍｍの大きさに成型し（直径０．３ｍｍニオブワイヤーを共に成型しリードとした）た後、１３００℃で７×１０^-3Ｐａの減圧下で焼結し焼結体とした。焼結体のＣＶ値を表１に示した。次に、焼結体の化成時間を１０００分にした以外は，ＣＶ値を求める場合と同様にして化成した後、他方の電極材料をポリピロール（酸化剤を過硫酸アンモニウム、ドーパントをアンソラキノンスルフォン酸ナトリウムとし、ドーパントの存在下、ピロールと酸化剤との反応を繰り返した）として焼結体内部の細孔に充填した。さらにカーボンペースト、銀ペーストを順に積層した後、エポキシ樹脂で封止してコンデンサを作製した。各例の容量出現率を表１に記載した。
実施例６〜１０、比較例４〜６
実施例１〜５、比較例１〜３で他方の電極材料をポリピロールから二酸化鉛と硫酸鉛の混合物（二酸化鉛が９８質量％、焼結体細孔中で酢酸鉛水溶液と過硫酸アンモニウム水溶液の反応を繰り返した。）とした以外は実施例１〜５、比例１〜３と同様にしてコンデンサを作製した。
実施例１１〜１５、比較例７〜９
実施例１〜５、比較例１〜３ で、ニオブ粉の平均粒径を０．８μｍから１．５μｍ（比表面積２．１ｃｍ²／ｇ）にし、トリエトキシリンをリン酸に変更し、さらに造粒粉の平均粒径を１３０μｍ（比表面積１．０ｃｍ²／ｇ）にした以外は実施例１〜５、比較例１〜３と同様にしてコンデンサを作製した。
実施例１６〜２０、比較例１０〜１２
実施例１〜５、比較例１〜３ で、平均粒径０．８μｍのニオブ粉から平均粒径０．７５μｍ（比表面積１．５ｃｍ²／ｇ）のタンタル粉にし、さらに造粒粉の平均粒径を１５０μｍ（比表面積０．７ｃｍ²／ｇ）にし、焼結温度を１３００℃から１３５０℃にした以外は、実施例１〜５、比較例１〜３ と同様にしてコンデンサを作製した。
以上作製したコンデンサの耐湿値を表１に付記した。
【００４３】
【表１】

【００４４】
実施例１〜５と比較例１〜３、実施例６〜１０と比較例４〜６、実施例１１〜１５と比較例７〜９、実施例１６〜２０と比較例１０〜１２を各々見比べることにより、リンを３質量ｐｐｂ〜１質量ｐｐｍ含有した土酸金属を主成分とする粉体からコンデンサを作製すると、該コンデンサの容量出現率が、大きくなり、また耐湿値が改良されることがわかる。
【００４５】
【発明の効果】
本発明のコンデンサ用粉体、これを用いた焼結体、この焼結体を一方の電極とし、その表面上に形成された誘電体と他方の電極とからコンデンサを構成することにより、容量出現率が大きく、耐湿値が良好なコンデンサを作製することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a capacitor having a large capacity appearance rate and a good moisture resistance value, a powder for the capacitor, and a sintered body using the powder.
[0002]
[Prior art]
Soil metal represented by tantalum, niobium and the like is a chemically stable metal and is used in various applications. For example, tantalum is widely used as a capacitor material for electronic devices such as mobile phones and personal computers. Niobium, which has just begun research as a capacitor material, is highly evaluated for its high dielectric constant performance. The form of the earth acid metal used as the capacitor material is usually a powder, and the powder is integrated by molding and sintering to form an electrode called a sintered body. Moreover, the powder material from which such a capacitor electrode is obtained is also called a capacitor powder.
[0003]
The inside of the sintered body has a three-dimensional complicated shape in which the powder is electrically and mechanically connected. After the dielectric film layer is formed inside and outside these sintered bodies, a capacitor is configured by impregnating the material to be the other electrode. As long as the dielectric film layer adheres uniformly to the external surface of the sintered body, the capacitance of the produced capacitor greatly depends on the contact state between the other electrode material and the dielectric film layer. .
[0004]
In the past, it has been possible to improve the sinterability of the sintered body by mixing phosphorus into the capacitor powder and increase the specific surface area of the sintered body. For example, in Patent Document 1, the addition of 5 to 600 ppm of phosphorus increases the CV value (the product of the capacity in the electrolyte and the formation voltage when forming the dielectric film. The physical property value is proportional to the specific surface area). It is described to do. However, by adding a much smaller concentration of phosphorus than this, the capacity after impregnation of the other electrode material was not increased without increasing the specific surface area of the sintered body. In addition, when phosphorus is added at a high concentration as conventionally known, the CV value increases as will be described later, but the capacity after impregnation of the other electrode material cannot be increased to the same extent as the increase rate of the CV value. .
[0005]
[Patent Document 1]
US Pat. No. 4,084,965 Specification
[Problems to be solved by the invention]
When the acetic acid aqueous solution was used as the other electrode material, the contact state with the dielectric film layer was complete, and assuming that the capacity appearance rate was 100%, a highly viscous electrode material, particularly a solid electrode material was used. In this case, it was difficult to set the capacity appearance rate to 100%. In particular, as the average particle size of the capacitor powder becomes smaller, the difficulty increases. In extreme cases, the capacity appearance rate may be less than 50%. Further, in the case of such a low capacity appearance rate, the moisture resistance value of the manufactured capacitor was poor. An object of the present invention is to solve these problems, and to provide a capacitor having a large capacity appearance rate and good moisture resistance, a sintered body capable of producing the capacitor, and a capacitor powder.
[0007]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have surprisingly been unable to use a powder for a capacitor mainly composed of a metal earth acid containing a very small amount of phosphorus. The inventors have found that a capacity appearance rate can be achieved and that the moisture resistance value of a capacitor using the powder is good, and thus the present invention has been completed. The main component is the most contained component, and more than 50% is the main component.
[0008]
That is, in the present invention, by adding a very small amount of phosphorus, it is possible to greatly increase the capacity after impregnation of the other electrode material without increasing the specific surface area of the sintered body. When phosphorus is added at a high concentration as conventionally known, the CV value increases as will be described later, but the capacity after impregnation of the other electrode material cannot be increased to the same level as the increase rate of the CV value. In the present invention, only the capacity appearance rate can be increased. It seems reasonable to think that the contact state between the other electrode material and the pores inside the sintered body has been improved by the addition of a small amount of phosphorus. The addition of a large amount of phosphorus can be interpreted as preventing the impregnation of the other electrode material. Moreover, when the specific surface area increases, the strength of the sintered body decreases, but in the present invention such a situation cannot occur.
[0009]
That is, the present invention relates to the following capacitor powder, a sintered body using the same, and a capacitor using the same.
(1) Capacitor powder mainly composed of metal earth acid, containing 3 mass ppb to 1 mass ppm of phosphorus.
(2) The capacitor powder as described in (1) above, wherein the earth acid metal is niobium.
(3) Capacitor powder according to item 1 or 2, wherein the average particle size of the capacitor powder is 0.2 μm or more and less than 5 μm.
(4) The capacitor powder according to any one of the preceding items 1 to 3, wherein the specific surface area of the capacitor powder is 0.5 to 15 m ² / g.
(5) Capacitor powder according to any one of items 1 to 4, wherein a part of the earth acid metal is nitrided.
(6) Capacitor powder having an average particle diameter of 10 to 300 μm obtained by granulating the capacitor powder according to any one of Items 1 to 5.
(7) A sintered body using the capacitor powder as set forth in any one of (1) to (6).
(8) The sintered body according to item 7 above, wherein the specific surface area of the sintered body is 0.2 to 7 m ² / g.
(9) A capacitor comprising the sintered body according to item 7 or 8 as one electrode and a dielectric formed on the surface thereof and the other electrode.
(10) The capacitor according to item 9 above, wherein the dielectric is mainly composed of niobium oxide or tantalum oxide.
(11) The capacitor as described in (10) above, wherein niobium oxide or tantalum oxide is formed by electrolytic oxidation.
(12) The other electrode is composed of an organic semiconductor, and the organic semiconductor is composed of an organic semiconductor composed of benzopyrroline tetramer and chloranil, an organic semiconductor composed mainly of tetrathiotetracene, and composed mainly of tetracyanoquinodimethane. Organic semiconductor, the following general formula (1) or (2)
[Chemical 3]

(In the formulas (1) and (2), R ^{1 to} R ⁴ represent hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. X represents an oxygen, sulfur or nitrogen atom, R ⁵ represents hydrogen or an alkyl group having 1 to 6 carbon atoms only when X is a nitrogen atom, R ¹ and R ² and R ³ and R ⁴ may be bonded to each other to form a ring.) Selected from the group consisting of organic semiconductors mainly composed of a conductive polymer doped with a dopant in a polymer containing two or more repeating units represented by 12. The capacitor according to any one of items 9 to 11, which is at least one organic semiconductor.
(13) The capacitor according to item 12 above, wherein the organic semiconductor is at least one selected from polypyrrole, polythiophene, and substituted derivatives thereof.
(14) The conductive polymer is represented by the following general formula (3)
[Formula 4]

(In the formula, R ⁶ and R ⁷ are each independently a hydrogen atom, a linear or branched saturated or unsaturated alkyl group having 1 to 6 carbon atoms, or the alkyl groups are bonded to each other at an arbitrary position. And represents a substituent that forms a cyclic structure of at least one or more 5- to 7-membered saturated hydrocarbon containing two oxygen elements, and the cyclic structure has an optionally substituted vinylene bond. 13. The capacitor according to item 12 above, which is a conductive polymer containing a repeating unit represented by the formula (1):
(15) The capacitor as described in (14) above, wherein the conductive polymer is a conductive polymer obtained by doping poly (3,4-ethylenedioxythiophene) with a dopant.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of obtaining the capacitor powder of the present invention will be described.
[0011]
Typical examples of the earth acid metal used in the present invention include tantalum, niobium, tantalum niobium alloys, and alloys based on these. Generally available powders can be used as the powder mainly composed of earth metal. For example, reduction of halogenated earth metal with magnesium or sodium, sodium reduction of potassium fluorinated metal acid, molten salt (NaCl + KCl) electrolysis of potassium metal fluorinated acid on a nickel cathode, metal oxide The oxide can be obtained by reduction with an alkali metal, alkaline earth metal, carbon or hydrogen, pulverization / dehydrogenation after introducing hydrogen into the earth acid metal ingot, or the like.
[0012]
As a starting material of phosphorus contained in the earth metal, phosphorus oxide, phosphorus nitride, phosphorus carbide, phosphorus sulfide, phosphorus silicide, metal phosphide (copper, silver, platinum, titanium, vanadium, chromium, manganese, iron, etc. Compound of metal and phosphorus), phosphate, and at least one selected from the group consisting of compounds represented by the following general formulas (4), (5), (6), and (7) and salts thereof Can be used.
[0013]
[Chemical formula 5]

[0014]
[Chemical 6]

[0015]
[Chemical 7]

[0016]
[Chemical 8]

[0017]
(In the general formulas (4) to (7), R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently hydrogen, a hydroxyl group, an alkyl group having 6 or less carbon atoms, or an alkoxy having 6 or less carbon atoms. Represents a group selected from a group, an aryl group, and a halogen, and when a portion other than R ¹ of the compounds represented by the general formulas (4) to (7) is R ^X , R ¹ and R ² are Independently, it may be R ^X or O—R ^X , that is, the compound represented by the general formulas (4) to (7) is a phosphorus compound having a phosphorus-phosphorus bond or a phosphorus-oxygen-phosphorus bond. It may be a multimer.)
[0018]
Examples of the compounds represented by the general formulas (4) to (7) include, for example, phosphorus halide, trialkoxylin, trialkoxyphosphate, ammonium hexafluorophosphate, and polyphosphoric acid.
[0019]
The content of phosphorus contained in the earth metal is 3 mass ppb to 1 mass ppm, preferably 10 mass ppb to 1 mass ppm. If it is out of this range, the effect of the present invention cannot be expected.
[0020]
As a method of incorporating a phosphorus compound into the earth acid metal, a predetermined amount of the phosphorus compound is mixed with the earth acid metal powder, or a predetermined amount of the phosphorus compound is mixed with the raw material or intermediate when the earth acid metal powder is produced. Alternatively, when the earth metal is an ingot, a predetermined amount of a phosphorus compound is mixed in the ingot preparation stage (the amount of phosphorus scattered during the ingot preparation is examined in a preliminary experiment), so-called phosphorus-earth metal One method is to make an alloy ingot.
[0021]
The average particle size of the powder containing phosphorus earth as a main component is 0.1 μm or more and less than 5 μm, preferably 0.2 μm or more and less than 2 μm. If the average particle size is 5 μm or more, the CV value of the produced sintered body itself is small, and it is difficult to produce a capacitor having a large capacity. If it is less than 0.1 μm, it is difficult to impregnate the other electrode material even with the present invention. The specific surface area of the powder of the present invention in the average particle size range is 0.5 to 15 m ² / g. The capacitor powder of the present invention may be used by granulating the powder into a predetermined size.
A conventionally known method can be adopted as the granulation method. For example, a method in which the powder is left in a high temperature vacuum of 500 ° C. to 2000 ° C. and then wet or dry pulverized, a method in which an appropriate binder such as acrylic resin or polyvinyl alcohol is mixed with the powder, and then pulverized. Examples thereof include a method of mixing with an appropriate compound such as resin and camphor, leaving it in a high temperature vacuum, and then wet or dry crushing. The particle size of the granulated powder can be arbitrarily changed depending on the degree of granulation and pulverization, but those having an average particle size of 10 μm to 300 μm are usually used. You may classify and use after granulation and crushing. Further, an appropriate amount of powder before granulation after granulation may be mixed and used.
[0022]
The capacitor powder (including the granulated powder) of the present invention is preferably a partially nitrided powder. The amount of nitriding is several tens mass ppm to several tens of thousands mass ppm. When a sintered body is produced from the powder and a dielectric is formed on the surface of the sintered body as described later, and an LC value is measured in an acetic acid aqueous solution, the nitriding is performed in order to obtain a small LC value. The amount is preferably 300 to 7000 mass ppm. Here, the amount of nitriding is not the amount adsorbed on the powder, but the amount nitrided by reaction.
[0023]
The nitriding of the powder can be performed by any one of liquid nitriding, ion nitriding, gas nitriding, or a combination thereof. Gas nitriding treatment in a nitrogen gas atmosphere is preferable because the apparatus is simple and easy to operate. For example, a gas nitriding method using a nitrogen gas atmosphere is achieved by leaving the powder in a nitrogen atmosphere. The nitriding atmosphere temperature is 2000 ° C. or less, and the standing time is within several hours to obtain a powder having a desired nitriding amount. Processing time can be shortened by processing at high temperature. The amount of nitriding of the powder can be managed under the condition that the nitriding temperature and nitriding time of the object to be nitrided are confirmed by a preliminary experiment or the like.
[0024]
When the granulated powder is nitrided, a granulated powder may be produced from the nitrided ungranulated powder and further subjected to nitriding treatment.
[0025]
The sintered body of the present invention is manufactured by sintering the powder described above. An example of a method for producing a sintered body is shown below. In addition, the manufacturing method of a sintered compact is not limited to this example. For example, it can be obtained by pressure-molding the powder into a predetermined shape and heating it at 500 ^-1 to 10 ^-4 Pa for several minutes to several hours at 500 to 2000 ° C. The specific surface area of such a sintered body is usually 0.2 to 7 m ² / g.
[0026]
In addition, a lead wire made of a valve metal such as niobium or tantalum having an appropriate shape and length is prepared, and a part of the lead wire is inserted into the molded body during the above-described pressure molding of the powder. Thus, the lead wire can be designed to be a lead for the sintered body.
[0027]
A capacitor can be manufactured from the above-mentioned sintered body as one electrode and a dielectric interposed between the other electrodes. Examples of the dielectric of the capacitor include a dielectric mainly composed of niobium oxide and tantalum oxide. For example, a dielectric containing niobium oxide as a main component can be obtained by forming a niobium sintered body as one electrode in an electrolytic solution. In order to form the niobium electrode in the electrolyte, it is usually a protonic acid aqueous solution such as 0. 1% acetic acid aqueous solution or sulfuric acid aqueous solution is used. When a niobium electrode is formed in an electrolytic solution to obtain a dielectric material mainly composed of niobium oxide. The capacitor of the present invention serves as an electrolytic capacitor, and the niobium side serves as an anode.
[0028]
On the other hand, the other electrode of the capacitor of the present invention includes at least one compound selected from organic semiconductors and inorganic semiconductors. Specific examples of the organic semiconductor include an organic semiconductor composed of benzopyrroline tetramer and chloranil, an organic semiconductor mainly composed of tetrathiotetracene, an organic semiconductor mainly composed of tetracyanoquinodimethane, and the following general formula (1) Or the organic semiconductor which has as a main component the electroconductive polymer which doped the dopant to the polymer containing the repeating unit represented by (2) is mention | raise | lifted.
[0029]
[Chemical 9]

[0030]
In the formulas (1) and (2), R ^{1 to} R ⁴ represent hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, which may be the same or different from each other. Well, X represents an oxygen, sulfur or nitrogen atom, R ⁵ is present only when X is a nitrogen atom and represents hydrogen or an alkyl group having 1 to 6 carbon atoms, R ¹ and R ² and R ³ and R ⁴ May be bonded to each other to form a ring.
[0031]
Furthermore, in the present invention, the conductive polymer containing the repeating unit represented by the general formula (1) is preferably a conductive polymer containing a structural unit represented by the following general formula (3) as a repeating unit. Can be mentioned.
[0032]
[Chemical Formula 10]

[0033]
In the formula, R ⁶ and R ⁷ are each independently a hydrogen atom, a linear or branched saturated or unsaturated alkyl group having 1 to 6 carbon atoms, or the alkyl group is bonded to each other at an arbitrary position. And a substituent that forms a cyclic structure of at least one 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. A conductive polymer containing such a chemical structure is charged and doped with a dopant. A well-known dopant can be used for a dopant without a restriction | limiting.
[0034]
Examples of the polymer containing the repeating unit represented by the formulas (1) to (3) include polyaniline, polyoxyphenylene, polyphenylene sulfide, polythiophene, polyfuran, polypyrrole, polymethylpyrrole, and substituted derivatives and co-polymers thereof. Examples include coalescence. Of these, polypyrrole, polythiophene, and substituted derivatives thereof (for example, poly (3,4-ethylenedioxythiophene)) are preferable.
[0035]
Specific examples of inorganic semiconductors. Examples thereof include an inorganic semiconductor mainly composed of lead dioxide or manganese dioxide, and an inorganic semiconductor composed of iron trioxide. Such semiconductors may be used alone or in combination of two or more.
[0036]
When the organic semiconductor and the inorganic semiconductor having a conductivity in the range of 10 ⁻² to 10 ³ S / cm are used, the impedance value of the manufactured capacitor is further reduced, and the capacitance at high frequency can be further increased. .
[0037]
Furthermore, when the other electrode is solid, a conductor layer may be provided thereon in order to improve electrical contact with an external lead (eg, lead frame).
[0038]
The conductor layer can be formed, for example, by solidifying a conductive paste, plating, metal vapor deposition, or forming a heat-resistant conductive resin film. As the conductive paste, a silver paste, a copper paste, an aluminum paste, a carbon paste, a nickel paste, or the like is preferable, but these may be used alone or in combination of two or more. When using 2 or more types, they may be mixed or may be stacked as separate layers. After applying the conductive paste, it is left in the air or heated to solidify. Examples of the plating include nickel plating, copper plating, silver plating, and aluminum plating. Examples of the deposited metal include aluminum, nickel, copper, and silver.
[0039]
Specifically, for example, a carbon paste and a silver paste are sequentially laminated on the other electrode and sealed with a material such as an epoxy resin to form a capacitor. The capacitor may have niobium or tantalum leads that are sintered together with the sintered body or later welded.
[0040]
The capacitor of the present invention having the above-described configuration can be made into a capacitor product for various uses by using, for example, an exterior such as a resin mold, a resin case, a metallic exterior case, a resin dipping, or an exterior with a laminate film.
[0041]
【Example】
Hereinafter, specific examples of the present invention will be described in more detail.
[0042]
The trace amount of phosphorus contained in the powder of the present invention was measured by a method using a flow injection / ICP-MS system developed by the present applicant. The flow injection system consists of a peristaltic pump (MP-32 manufactured by Tokyo Science Machinery Co., Ltd.), a valve made of polytetrafluoroethylene (5020 and 5011 made by Leodyne), an anion exchange column assembly (a strong base in a polytetrafluoroethylene tube). Ion exchange resin <filled with Muromachi Chemical Dowex1-X8 50-100 mesh), polytetrafluoroethylene membrane filter (FG, pore size 0.2 μm, area 4.0 cm ² by Nippon Millipore Industries), and polytetrafluoroethylene tube (Connecting tube inner diameter 0.8 mm, reaction tube 2.0 mm), which are connected using the above-described ICP-MS (SPQ8000 manufactured by Seiko Instruments Inc.), a membrane filter portion, and a polytetrafluoroethylene tube. The system was installed in a class 1000 clean room. Further, the nitriding amount of the powder was obtained using a nitrogen / oxygen analyzer manufactured by LEKO. The CV value of the sintered body was obtained from the product of the capacity measured in 30% sulfuric acid after applying 20 V in a 0.1% acetic acid aqueous solution at 80 ° C. for 200 differentiation and a conversion voltage of 20 V. Further, the capacity appearance rate was expressed as a ratio with the capacity after the capacitor formation, assuming that the capacity in 30% sulfuric acid when 1000 differentiation was performed under the above-mentioned conditions was 100%. The moisture resistance value of the capacitor was expressed by the number of capacitors produced when the capacitor was allowed to stand at 60 ° C. and 95% RH for 500 hours exceeding 120% of the initial value. The smaller the number, the better the moisture resistance. The number of samples for obtaining the CV value, the capacity appearance rate, and the moisture resistance value was 30 in each example.
Examples 1-5, Comparative Examples 1-3
To niobium powder having an average particle size of 0.8 μm (specific surface area of 3.8 cm ² / g), separately prepared triethoxy phosphorus was added in a predetermined amount to adjust the phosphorus amount to the content shown in Table 1. . Subsequently, the powder of each example was heated at 1200 ° C. under vacuum, taken out, classified after pulverization, and granulated powder (specific surface area 1.3 cm ² / g) having an average particle diameter of 90 μm. From this granulated powder, each example was molded to a size of 1.8 × 3.5 × 4.5 mm (a niobium wire having a diameter of 0.3 mm was formed as a lead), and then 7 × 10 at 1300 ° C. Sintered under reduced pressure of ⁻³ Pa to obtain a sintered body. The CV value of the sintered body is shown in Table 1. Next, except that the formation time of the sintered body was changed to 1000 minutes, the other electrode material was formed in the same manner as in the case of obtaining the CV value, and then the other electrode material was polypyrrole (the oxidizing agent was ammonium persulfate, the dopant was anthoraquinone sulfonic acid The reaction was repeated with pyrrole and oxidizing agent in the presence of a dopant in the presence of a dopant, and the pores inside the sintered body were filled. Further, a carbon paste and a silver paste were laminated in order, and then sealed with an epoxy resin to produce a capacitor. The capacity appearance rate of each example is shown in Table 1.
Examples 6-10, Comparative Examples 4-6
In Examples 1 to 5 and Comparative Examples 1 to 3, the other electrode material was a mixture of lead dioxide and lead sulfate from polypyrrole (reaction of lead acetate aqueous solution and ammonium persulfate aqueous solution in the sintered body pores with 98% by mass of lead dioxide. A capacitor was fabricated in the same manner as in Examples 1 to 5 and proportionalities 1 to 3 except that the above was repeated.
Examples 11-15, Comparative Examples 7-9
In Examples 1 to 5 and Comparative Examples 1 to 3, the average particle size of the niobium powder was changed from 0.8 μm to 1.5 μm (specific surface area 2.1 cm ² / g), triethoxy phosphorus was changed to phosphoric acid, Capacitors were produced in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 3, except that the average particle size of the granulated powder was 130 μm (specific surface area 1.0 cm ² / g).
Examples 16-20, Comparative Examples 10-12
In Examples 1 to 5 and Comparative Examples 1 to 3, niobium powder having an average particle diameter of 0.8 μm was changed to tantalum powder having an average particle diameter of 0.75 μm (specific surface area 1.5 cm ² / g), and the average of the granulated powder Capacitors were produced in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 3, except that the particle size was 150 μm (specific surface area 0.7 cm ² / g) and the sintering temperature was changed from 1300 ° C. to 1350 ° C.
The moisture resistance values of the capacitors thus prepared are shown in Table 1.
[0043]
[Table 1]

[0044]
Examples 1-5 and Comparative Examples 1-3, Examples 6-10, Comparative Examples 4-6, Examples 11-15, Comparative Examples 7-9, Examples 16-20, and Comparative Examples 10-12 are compared. As a result, when a capacitor is produced from a powder mainly composed of metal earth acid containing 3 mass ppb to 1 mass ppm of phosphorus, the capacity appearance rate of the capacitor is increased and the moisture resistance is improved. Recognize.
[0045]
【The invention's effect】
Capacitor powder of the present invention, a sintered body using the same, and using this sintered body as one electrode, and forming a capacitor from the dielectric formed on the surface and the other electrode, the capacitance appears A capacitor having a high rate and good moisture resistance can be manufactured.

Claims (12)

Capacitor powder containing niobium or tantalum containing 3 mass parts ppb to 1 mass ppm of phosphorus and having an average particle size of 0.1 μm or more and less than 5 μm and a specific surface area of 0.5 to 15 m ² / g . 2. The capacitor powder according to claim 1, wherein a part of niobium or tantalum is nitrided. A capacitor powder having an average particle size of 10 to 300 μm, which is obtained by granulating the capacitor powder according to claim 1. A sintered body using the capacitor powder according to any one of claims 1 to 3 . The sintered body according to claim 4 , wherein the sintered body has a specific surface area of 0.2 to 7 m ² / g. A capacitor comprising the sintered body according to claim 4 or 5 as one electrode and a dielectric formed on the surface thereof and the other electrode. The capacitor according to claim 6 , wherein the dielectric is mainly composed of niobium oxide or tantalum oxide. The capacitor according to claim 7 , wherein niobium oxide or tantalum oxide is formed by electrolytic oxidation. The other electrode is composed of an organic semiconductor, the organic semiconductor is composed of a benzopyrroline tetramer and chloranil, an organic semiconductor composed mainly of tetrathiotetracene, an organic semiconductor composed mainly of tetracyanoquinodimethane, The following general formula (1) or (2)

(In the formulas (1) and (2), R ^{1 to} R ⁴ represent hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. X represents an oxygen, sulfur or nitrogen atom, R ⁵ represents hydrogen or an alkyl group having 1 to 6 carbon atoms only when X is a nitrogen atom, and R ¹ and R ² and R ³ and R ⁴ may be bonded to each other to form a ring.) Selected from the group consisting of organic semiconductors mainly composed of a conductive polymer doped with a dopant in a polymer containing two or more repeating units represented by capacitor according to any one of claims 6 to 8 is at least one organic semiconductor. Conductivity polymer is polypyrrole, polythiophene and capacitor according to claim 9 is at least one selected from the substituted derivatives thereof. The conductive polymer is represented by the following general formula (3)

(Wherein R ⁶ and R ⁷ are each independently a hydrogen atom, a linear or branched saturated or unsaturated alkyl group having 1 to 6 carbon atoms, or the alkyl group is bonded to each other at an arbitrary position. And a substituent that forms a cyclic structure of at least one or more 5- to 7-membered saturated hydrocarbons containing two oxygen elements, and the cyclic structure has an optionally substituted vinylene bond. having one capacitor of claim 9 or 10, which is a conductive polymer containing a repeating unit represented by.) which include the phenylene structure which may be substituted. The capacitor according to claim 11, wherein the conductive polymer is a conductive polymer obtained by doping poly (3,4-ethylenedioxythiophene) with a dopant.