JP4683512B2 - Capacitor powder, sintered body using the same, and capacitor using the same - Google Patents
Capacitor powder, sintered body using the same, and capacitor using the same Download PDFInfo
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- JP4683512B2 JP4683512B2 JP2000366039A JP2000366039A JP4683512B2 JP 4683512 B2 JP4683512 B2 JP 4683512B2 JP 2000366039 A JP2000366039 A JP 2000366039A JP 2000366039 A JP2000366039 A JP 2000366039A JP 4683512 B2 JP4683512 B2 JP 4683512B2
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/045—Alloys based on refractory metals
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、単位質量当たりの容量が大きく、漏れ電流特性の良好なコンデンサを製造することができる土酸金属（主として、ニオブ、タンタル）粉体に関する。さらに詳しく言えば、特定量のジルコニウムを含有する、ニオブ粉体、タンタル粉体及びニオブ−タンタル合金粉体、それらを粉体用いた焼結体、並びにその焼結体を用いたコンデンサに関する。
【０００２】
【背景技術】
携帯電話やパーソナルコンピュータ等の電子機器に使用されるコンデンサは、小型で大容量のものが望まれている。このようなコンデンサの中でもタンタルコンデンサは大きさの割には容量が大きく、性能が良好なため、好んで使用されている。タンタルコンデンサの陽極体として、一般的にタンタル粉の焼結体が使用されている。これらタンタルコンデンサの容量を上げるためには、焼結体質量を増大させるか、またはタンタル粉を微粉化して表面積を増加させた焼結体を用いる必要がある。
【０００３】
焼結体質量を増加させる方法では、コンデンサの形状が必然的に増大して小型化の要求を満たさない。一方、タンタル粉を微粉化して比表面積を増加させる方法では、タンタル焼結体の細孔径が小さくなり、また焼結段階で閉鎖孔が多くなり、後工程における陰極剤の含浸が困難になる。これらの欠点を解決するためには、焼結段階での閉鎖孔を少なくする方法、タンタルより誘電率の大きい材料を用いてコンデンサを作成する方法などが考えられる。これらの誘電率の大きい材料としてニオブがある。
【０００４】
特開昭５５−１５７２２６号公報には、粒径２．０μｍあるいはそれ以下のニオブ微粉末（一次粉体）の凝集粉を加圧成形して焼結し、その成から形焼結体を細かく裁断して、これにリード部を接合した後再び焼結するコンデンサ用焼結素子の製造方法が開示されている。しかしながら、この公報には焼結素子を用いたコンデンサの特性についての詳細は示されてない。
【０００５】
米国特許４０８４９６５号公報には、ニオブインゴットを水素化して微砕化し、５．１μｍのニオブ粉末を得、これを用いたコンデンサが開示されているが、ニオブ焼結体は、漏れ電流値（以下、ＬＣ値と略記する。）が大きく、実用性に乏しい。
特開平１０−２４２００４号公報には、ニオブ粉の一部を窒化すること等により、ＬＣ値を改善することが開示されている。しかしながら、粒径の細かなニオブ粉を用いて、ニオブ焼結体から高容量なコンデンサを作成する場合、ＬＣ値が特異的に大きなコンデンサが出現する場合があった。
【０００６】
【発明が解決しようとする課題】
したがって、本発明の目的は、単位質量当たりの容量が大きく、漏れ電流値の小さいコンデンサを提供し得るコンデンサ用粉体、それを用いた焼結体及びその焼結体を用いたコンデンサを提供することにある。
【０００７】
【課題を解決するための手段】
本発明者は、前述の課題を鋭意検討した結果、特定量のジルコニウムをニオブ、タンタル、ニオブ−タンタル合金に含有させることにより、平均粒径の小さな粉体を用いて焼結を行っても比表面積を大きく保つことができること、またこの焼結体を用いてコンデンサとした場合に大容量で、かつＬＣが低く安定なコンデンサが得られることを見出し、本発明を完成した。
すなわち、本発明は、以下のコンデンサ用粉体、それを用いた焼結体及びそれを用いたコンデンサに関する。
【０００８】
１．ジルコニウムを含み、ニオブ及び／またはタンタルを主成分とするコンデンサ用粉体。
２．ジルコニウムを０．０１〜１５原子％含み、ニオブ及び／またはタンタルを主成分とする前記１に記載のコンデンサ用粉体。
３．ニオブを主成分とする前記１または２に記載のコンデンサ用粉体。
４．タンタルを主成分とする前記１または２に記載のコンデンサ用粉体。
５．ニオブ−タンタル合金を主成分とする前記１に記載のコンデンサ用粉体。
６．平均粒径が０．２μｍ〜５μｍである前記１乃至５のいずれかに記載のコンデンサ用粉体。
７．比表面積が０．５〜１５ｍ2／ｇである前記１乃至５のいずれかに記載のコンデンサ用粉体。
８．ニオブ及び／またはタンタルの一部が窒素、炭素、ホウ素、硫黄の少なくとも１つと化合している前記１乃至５のいずれかに記載のコンデンサ用粉体。
９．前記１乃至８のいずれかに記載のコンデンサ用粉体を造粒してなることを特徴とする平均粒径２０〜５００μｍのコンデンサ用粉体。
１０．前記１乃至９のいずれかに記載のコンデンサ用粉体を用いた焼結体。
１１．比表面積が０．５〜５ｍ2／ｇである前記１０に記載の焼結体。
１２．前記１０または１１に記載の焼結体を一方の電極とし、その焼結体表面上に形成された誘電体と、前記誘電体上に設けられた他方の電極とから構成されるコンデンサ。
１３．誘電体が酸化ニオブ及び／または酸化タンタルを含む前記１２に記載のコンデンサ。
１４．酸化ニオブ及び／または酸化タンタルが電解酸化により形成されたものである前記１３に記載のコンデンサ。
１５．他方の電極が、電解液、有機半導体及び無機半導体から選ばれる少なくとも１種の材料である前記１２に記載のコンデンサ。
１６．他方の電極が有機半導体からなり、該有機半導体がベンゾピロリン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、及び下記一般式（１）または（２）
【化２】
で示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導電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る少なくとも１種の有機半導体である前記１５に記載のコンデンサ。
１７．有機半導体が、ポリピロール、ポリチオフェン及びこれらの置換誘導体から選ばれる少なくとも１種である前記１６に記載のコンデンサ。
【０００９】
【発明実施の形態】
本発明は、ジルコニウムを含むコンデンサ用のニオブ粉体、タンタル粉体、ニオブ−タンタル合金粉体に関するが、これらの粉体材料は同じような性能を示すため、以下ニオブ粉体を例に挙げて説明する。
【００１０】
コンデンサの容量は一般に次式で示される。
【数１】
Ｃ＝ε×（Ｓ／ｄ）
（Ｃ：容量、ε：誘電率、Ｓ：比面積、ｄ＝電極間距離）
ここで、ｄ＝ｋ×Ｖ（ｋ：定数、Ｖ：化成電圧）であるので、Ｃ＝ε×（Ｓ／（ｋ×Ｖ））、さらにＣ×Ｖ＝（ε／ｋ）×Ｓが導かれる。したがって、比面積（Ｓ）を大きくすることにより容量を大きくできる。
【００１１】
コンデンサに用いる焼結体の比表面積を大きくする第一の手段は、コンデンサに用いる粉体の粒度を小さくすることである。本発明では、焼結体を作製するジルコニウムを含有するニオブ粉の一次粒子の平均粒径を５μｍ未満にすることにより、粉体の比表面積を実用的レベルまで大きくすることができる。
【００１２】
本発明者が一例として作製したジルコニウム含有ニオブ粉（粉砕法）の粒径と比表面積を表１に示す。
【表１】
【００１３】
表１から明らかなように、ジルコニウムを含有するニオブ粉はその平均粒径を小さくすることにより比表面積を大きくできるが、ジルコニウムを含有するニオブ粉の平均粒径を０．２μｍ未満にすると、焼結体を作製した場合に細孔径が小さくなり、また閉鎖孔が多くなるため、後の工程での陰極剤の含浸が困難になる。そのため、結果として容量を大きくすることができず、実用に適さない。また、平均粒径が５μｍ以上の場合には比表面積が小さくなるため大きな容量が得られない。従って、本発明においてジルコニウムを含有するニオブ粉の平均粒径は０．２μｍ以上５μｍ未満が好ましい。
【００１４】
コンデンサに用いる焼結体の比表面積を大きくする第二の手段は、平均粒径の小さな粉体を用いつつ焼結時の閉鎖孔の生成を抑えて焼結体としたときに比表面積が小さくならないようことである。通常、焼結する温度を低くすれば比表面積を保つことができるが、焼結温度が低くなると焼結体の強度が低下し破損しやすくなる。
本発明においては、焼結体用のニオブ粉、タンタル粉またはニオブ−タンタル合金粉に、ジルコニウムを特定量含有させることにより、必要な強度が得られる焼結温度で大きな比表面積を有する焼結体とすることができる。
本発明者が作製したジルコニウム含有ニオブ焼結体の一例の比表面積とジルコニウムを含有していないニオブ焼結体の比表面積を表２に示す。
【００１５】
【表２】
表２から明らかなように実用的な強度が得られる温度で焼結する場合において、ジルコニウムを含有させることにより、ジルコニウムを含有させないニオブ粉に比べて約１．５倍の比表面積を保つことができる。
【００１７】
また、ジルコニウムを含有するニオブ粉は、その平均粒径を小さくして高容量の焼結体を作製した場合においても、ＬＣ値が特異的に大きくなることはない。その理由の詳細は不明であるが以下のように推定される。
ニオブは、酸素元素との結合力が大きいため、電解酸化皮膜中の酸素が内部のニオブ金属側に拡散しやすい。しかしながら、本発明における焼結体は、内在するジルコニウムがニオブと結合する等の相互作用をするために電解酸化皮膜中の酸素が焼結体内部のニオブ金属と結合しにくくなり、金属側への酸素の拡散が抑制され、その結果電解酸化皮膜の安定性を保つことが可能となり、粒径が細かく高容量のコンデンサにおいてもＬＣを低下させ、ばらつきを小さくする効果が得られるものと考えられる。
【００１８】
本発明においては焼結体を作製用のニオブ粉中のジルコニウムの含有量は重要であり、０．０１〜１５原子％が好ましく、作製されるコンデンサ容量と漏れ電流値のバランスから、特に０．０５〜３原子％が好ましい。
ジルコニウムの含有量が低すぎると、前述の電解酸化皮膜中の酸素が内部のニオブ金属側に拡散しやすい性質を抑制することができず、結果として電解酸化皮膜の安定性を保つことが不可能となり、ＬＣを低下させる効果が得られない。また、多すぎるとジルコニウムを含有するニオブ粉中のニオブ含有量が減少し、容量が低下する。
【００１９】
焼結体の作製に用いられる本発明のジルコニウム含有ニオブ粉は、平均粒径が０．２μｍ〜５μｍが好ましい。
このような平均粒径を有するジルコニウム含有ニオブ粉は、例えばニオブ−ジルコニウム合金インゴット、ペレット、粉体などの水素化物を粉砕した後、脱水素することにより製造することができる。ジルコニウム含有ニオブ粉の平均粒径は、ニオブ−ジルコニウム合金の水素化量、粉砕時間、粉砕装置などを適宜変更することにより、所望の範囲に調整することができる。
また、上記で得られたジルコニウム含有ニオブ粉にジルコニウムを含まない平均粒径０．２μｍ以上で５μｍ未満の他のニオブ粉を混合しジルコニウム含有量を調整してもよい。
このようなニオブ粉は、例えば、ニオブインゴット、ペレット、粉体の水素化物を粉砕した後、脱水素する方法、フッ化ニオブ酸カリウムをナトリウム還元したものを粉砕する方法、酸化ニオブをアルカリ金属、アルカリ土類金属、タンタル、ニオブ、アルミニウム、水素、炭素などにより還元する方法等によって得ることができる。
【００２０】
本発明のジルコニウム含有ニオブ粉は、ジルコニウムを含まないニオブ粉に金属ジルコニウムあるいはジルコニウム化合物の粉体を混合したものでもよい。ここで、ジルコニウム化合物としては、炭化ジルコニウム、酸化ジルコニウム（安定化ジルコニアを含む）、ジルコニウムアルコキシド、硼化ジルコニウム、窒化ジルコニウム、硫化ジルコニウム、珪化ジルコニウム、水素化ジルコニウム、水酸化ジルコニウム、硫酸ジルコニウム、珪酸ジルコニウム、ハロゲン化ジルコニウム、オキシハロゲン化ジルコニウム、オキシ酢酸ジルコニウム、オキシ硝酸ジルコニウムなどが使用でき、これらは単独でも２種以上を組み合わせて用いてもよい。
【００２１】
また、本発明のジルコニウム含有ニオブ粉は、酸化ニオブと酸化ジルコニウムの混合物をアルカリ金属、アルカリ土類金属、タンタル、ニオブ、アルミニウム、水素、炭素などにより還元する方法によっても得ることができる。
【００２２】
本発明のジルコニウム含有ニオブ粉は、漏れ電流値をさらに改善するために、ジルコニウム含有ニオブ粉の一部が窒素、炭素、ホウ素、硫黄の少なくとも一つと結合しているものであってもよい。窒素、炭素、ホウ素、硫黄の結合物であるジルコニウム含有ニオブ窒化物、ジルコニウム含有ニオブ炭化物、ジルコニウム含有ニオブホウ化物、ジルコニウム含有ニオブ硫化物はいずれかを単独で含有しても良く、またこれらの２種、３種、４種の組合せであってもよい。
【００２３】
その結合量（窒素、炭素、ホウ素、硫黄の含有量の総和）は、ジルコニウム含有ニオブ粉の形状にもよって変わるが、平均粒径０．２〜５μｍ程度の粉で５０〜２０００００ｐｐｍ、好ましくは、２００〜２００００ｐｐｍである。５０ｐｐｍ未満では、ＬＣ特性に改善が見られず、２０００００ｐｐｍを越えると容量特性が悪化し、コンデンサとして適さない。
【００２４】
ジルコニウム含有ニオブ粉の窒化は、液体窒化、イオン窒化、ガス窒化あるいはそれらを組み合わせた方法で実施することができるが、中でも装置が簡便で操作が容易なガス窒化処理が好ましい。
ガス窒化は、前記ジルコニウム含有ニオブ粉を窒素ガス雰囲気中に放置することによって行うことができる。窒化する雰囲気の温度は、２０００℃以下、放置時間は、数時間以内で目的とする窒化量のジルコニウム含有ニオブ粉が得られる。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。
【００２５】
ジルコニウム含有ニオブ粉の炭化は、ガス炭化、固相炭化、液体炭化いずれであってもよい。例えば、ジルコニウム含有ニオブ粉を炭素材やメタンなどの炭素を有する有機物などの炭素源とともに、減圧下に２０００℃以下で数分〜数１０時間放置しておけばよい。
【００２６】
ジルコニウム含有ニオブ粉のホウ化は、ガスホウ化、固相ホウ化いずれであってもよい。例えば、ジルコニウム含有ニオブ粉をホウ素ペレットやトリフルオロホウ素などのハロゲン化ホウ素のホウ素源とともに、減圧下、２０００℃以下で数分〜数１０時間放置しておけばよい。
【００２７】
ジルコニウム含有ニオブ粉の硫化は、ガス硫化、イオン硫化、固相硫化いずれであってもよい。例えば、硫黄ガス雰囲気によるガス硫化の方法は、前記ジルコニウム含有ニオブ粉を硫黄雰囲気中に放置することにより達成される。硫化する雰囲気の温度は、２０００℃以下、放置時間は数１０時間以内で目的とする硫化量のジルコニウム含有ニオブ粉が得られる。また、より高温で処理することにより処理時間を短縮できる。
【００２８】
焼結体を製造するためのコンデンサ用ジルコニウム含有ニオブ粉は、前述したジルコニウム含有ニオブ一次粉を適当な形状に造粒したものであってもよいし、造粒後に未造粒のジルコニウム含有ニオブ粉またはニオブ粉を適量混合して使用してもよい。
造粒方法としては、例えば、未造粒のジルコニウム含有ニオブ粉を高真空下に放置し適当な温度に加熱した後解砕する方法、樟脳、ポリアクリル酸、ポリメチルアクリル酸エステル、ポリビニルアルコールなどの適当なバインダーとアセトン、アルコール類、酢酸エステル類、水などの溶媒と未造粒のジルコニウム含有ニオブ粉を混合した後に解砕する方法等が挙げられる。
【００２９】
造粒したジルコニウム含有ニオブ粉を用いることにより、焼結体を製造する際の加圧成形性が向上する。
造粒粉の平均粒径は２０〜５００μｍが好ましい。造粒粉の平均粒径が２０μｍ以下では部分的にブロッキングをおこし、金型への流動性が悪い。５００μｍ以上では加圧成形後の成形体の角の部分が欠けやすい。さらに、造粒粉の平均粒径を６０〜２５０μｍとすることにより、加圧成形体を焼結した後、コンデンサを製造する際の陰極剤が焼結体へ含浸しやすくなる。
【００３０】
本発明のコンデンサ用ジルコニウム含有ニオブ焼結体は、前述したジルコニウム含有ニオブ粉あるいは造粒したジルコニウム含有ニオブ粉を成形、焼結して製造する。焼結体の製造方法は特に限定されないが、例えば、ジルコニウム含有ニオブ粉を所定の形状に加圧成形した後、１０2〜１０-5Ｐａで、数分〜数時間、５００〜２０００℃、好ましくは９００〜１５００℃、さらに好ましくは９００〜１３００℃の範囲で加熱して得られる。
【００３１】
次に、コンデンサ素子の製造について説明する。
本発明のコンデンサは、前述した焼結体を一方の電極とし、その焼結体表面上に形成された誘電体と、前記誘電体上に設けられた他方の電極とから構成される。
例えば、ニオブまたはタンタルなどの弁作用金属からなる適当な形状および長さを有するリードワイヤーを用意し、ニオブ粉を焼結し加圧成形する際に、前記リードワイヤーの一部が成形体の内部に挿入されるように一体成形してリードワイヤーが焼結体の引き出しリードとなるように設計し組立てる。
【００３２】
コンデンサの誘電体としては、例えば、酸化タンタル、酸化ニオブ、高分子物質、セラミック化合物などからなる誘電体が挙げられるが、ジルコニウム含有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酸化ニオブを主体とする誘電体が好ましい。ジルコニウム含有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％リン酸水溶液、硫酸水溶液または１％の酢酸水溶液、アジピン酸水溶液等を用いて行われる。ジルコニウム含有ニオブ電極を電解液中で化成して酸化ニオブ誘電体を得る場合、本発明のコンデンサは、電解コンデンサとなりジルコニウム含有ニオブ電極が陽極となる。
【００３３】
本発明のコンデンサの他方の電極は、格別限定されるものではなく、例えば、アルミ電解コンデンサ業界で公知である電解液、有機半導体および無機半導体から選ばれる少なくとも１種の材料（化合物）が使用できる。
【００３４】
電解液の具体例としては、イソブチルトリプロピルアンモニウムボロテトラフルオライド電解質を５質量％溶解したジメチルホルムアミドとエチレングリコールの混合溶液、テトラエチルアンモニウムボロテトラフルオライドを７質量％溶解したプロピレンカーボネートとエチレングリコールの混合溶液等が挙げられる。
【００３５】
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）
【化３】
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導電性高分子を主成分とした有機半導体が挙げられる。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。
【００３６】
式（１）または（２）で示される繰り返し単位を２以上含む重合体としては、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。でもポリピロール、ポリチオフェンおよびこれらの置換誘導体（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。
なお、本明細書で「導電性高分子を主成分とする」とは有機半導体の原料モノマー中の不純物に由来する成分等を含有する導電性高分子をも含み得ること、すなわち「導電性高分子を実質的有効成分していること」を意味する。
【００３７】
また、ドーパントとしては、スルホキノン系ドーパント、アントラセンモノスルホン酸系ドーパントやその他種々のアニオン系ドーパントが使用できる。また、ＮＯ+，ＮＯ2 +塩などの電子受容体ドーパントを使用しても良い。
【００３８】
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挙げられる。
このような半導体は、単独で使用することができるが、２種以上組み合わせて使用しても良い。
【００３９】
上記有機半導体および無機半導体として、電導度１０-2Ｓ・ｃｍ-1〜１０3Ｓ・ｃｍ-1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をより小さくすることができ、高周波での容量をさらに大きくすることができる。
【００４０】
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。
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、アルミメッキ等が挙げられる。また蒸着金属としては、アルミニウム、ニッケル、銅、銀等が挙げられる。
【００４１】
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、ジルコニウム含有ニオブ焼結体と一体に焼結成形された、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。
【００４２】
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、ラミネートフィルムによる外装により各種用とのコンデンサ製品とすることができる。
【００４３】
他方の電極が液体の場合には、前記両極と誘電体から構成されたコンデンサを、例えば、他方の電極と電気的に接続した缶に収納してコンデンサが形成される。この場合、ジルコニウム含有ニオブ焼結体の電極側は、前記したニオブまたはタンタルリードを介して外部に導出すると同時に、絶縁性ゴムなどにより、缶との絶縁がはかられるように設計される。
【００４４】
【実施例】
以下、実施例および比較例を挙げ本発明を具体的に説明するが、本発明はこれらの例に限定されるものではない。なお、各例における焼結体の容量、漏れ電流値、およびチップ加工したコンデンサの容量、漏れ電流値の測定、評価方法は以下の通りである。
【００４５】
（１）焼結体の容量測定
室温において、３０％硫酸中に浸漬させた焼結体と硫酸液中に入れたタンタル材の電極との間にヒューレットパッカード社製のＬＣＲ測定器を接続し測定した１２０Ｈｚでの容量を焼結体の容量とした。
（２）焼結体の漏れ電流測定
室温において、２０％リン酸水溶液中に浸漬させた焼結体とリン酸水溶液中に入れた電極との間に誘電体作製時の化成電圧の７０％の電圧（１４Ｖ）の直流電圧を３分間印加し続けた後に測定された電流値を焼結体の漏れ電流値（ＬＣ値）とした。
（３）コンデンサの容量測定
室温において、作製したチップの端子間にヒューレットパッカード社製ＬＣＲ測定器を接続し、測定した１２０Ｈｚでの容量をチップ加工したコンデンサの容量とした。
（４）コンデンサの漏れ電流測定
室温において、定格電圧値（２．５Ｖ、４Ｖ、６．３Ｖ、１０Ｖ、１６Ｖ、２５Ｖ等）のうち誘電体作製時の化成電圧の約１／３〜約１／４に近い直流電圧（６．３Ｖ）を作製したチップの端子間に１分間印加し続けた後に測定された電流値をチップに加工したコンデンサの漏れ電流値とした。
【００４６】
実施例１：ジルコニウム含有ニオブ粉焼結体
ニオブインゴット９２ｇとジルコニウムの粉末１ｇを用い、アーク溶解でジルコニウムを１モル％含むジルコニウム含有ニオブインゴットを作製した。このインゴット５０ｇをＳＵＳ３０４製の反応容器に入れ、４００℃で１０時間水素を導入し続けた。冷却後、水素化されたジルコニウム含有ニオブ塊をＳＵＳ製ボールを入れたＳＵＳ３０４製のポットに入れ１０時間粉砕した。次に、ＳＵＳ３０４製の湿式粉砕機に、この水素化物を水で２０ｖｏｌ％のスラリーにしたものおよびジルコニアボールを入れ７時間湿式粉砕した。このスラリーを遠心沈降の後、デカンテーションして粉砕物を取得した。粉砕物を１３３Ｐａ（１Ｔｏｒｒ）、５０℃の条件で真空乾燥した。続いて、水素化ジルコニウム含有ニオブ粉を１．３３×１０-2Ｐａ（１×１０-4Ｔｏｒｒ）Ｐａ、４００℃で１時間加熱し脱水素した。作製したジルコニウム含有ニオブ粉の平均粒径は１．０μｍであり、ジルコニウム含有量を原子吸光分析により測定したところ、１モル％であった。このようにして得られた、ジルコニウム含有ニオブ粉を４×１０-3Ｐａ（３×１０-5Ｔｏｒｒ）の真空下、１０００℃で造粒した。その後、造粒塊を解砕し、平均粒径１２０μｍの造粒粉を得た。
得られたジルコニウム含有ニオブ造粒粉を０．３ｍｍφのニオブ線と共に成形し、およそ０．３×０．１８×０．４５ｃｍの成形体（約０．１ｇ）を作製した。この成形体を４×１０-3Ｐａ（３×１０-5Ｔｏｒｒ）の真空下、１２００℃で３０分放置することにより焼結体を得た。得られた焼結体のニオブ線の引っ張り強度を測定したところ、３ｋｇ／ｃｍ2（２．９×１０5Ｐａ）であり、十分な強度を有していた。続いて、焼結体を、０．１％リン酸水溶液中で、８０℃の温度で２００分間、２０Ｖの電圧で化成することにより、表面に誘電体層を形成した。この後、３０％硫酸中での容量と、２０％リン酸水溶液中での漏れ電流（以下「ＬＣ」と略す。）を各々測定した。結果を表３に示す。
【００４７】
実施例２〜１５：ジルコニウム含有ニオブ／タンタル粉焼結体
ジルコニウムの粉末とニオブインゴット、タンタルインゴット、またはニオブ−タンタル合金インゴットを任意の割合で用い、アーク溶解でジルコニウム含有ニオブインゴット、ジルコニウム含有タンタルインゴット、またはジルコニウム含有ニオブ−タンタルインゴットを作製した。
このインゴット５０ｇについて実施例１と同様な装置を用い、粉砕時間を調整して所望の粒径を有するジルコニウム含有ニオブ粉、ジルコニウム含有タンタル粉、ジルコニウム含有ニオブ−タンタル粉を得た。これら各粉体を用い、実施例１と同様に焼結体を作製し、容量とＬＣを各々測定した。結果を表３に示す。
【００４８】
比較例１〜６：ジルコニウムを含まないニオブ粉、タンタル粉、ニオブ−タンタル合金粉
実施例１と同様に操作することにより、ジルコニウムを含まないニオブ粉、タンタル粉、ニオブ−タンタル合金粉を調製した。この粉体を用いて実施例１と同様に焼結体を作製し容量とＬＣを測定した。結果を表３に示す。
【００４９】
比較例７〜８：ジルコニウムを過剰に含むニオブ粉
実施例１と同様に操作することにより、ジルコニウムを１８．７モル％、および２４．６モル％含むジルコニウム含有ニオブ粉を調製した。この粉体を用いて実施例１と同様に焼結体を作製し容量とＬＣを測定した。結果を表３に示す。
【００５０】
【表３】
実施例１６〜２１：ジルコニウム含有ニオブ粉焼結体
ニオブインゴット１００ｇをＳＵＳ３０４製の反応容器に入れ、４００℃で１０時間水素を導入し続けた。冷却後、水素化されたニオブ塊をＳＵＳ製ボールを入れたＳＵＳ３０４製のポットに入れ１０時間粉砕した。次に、ＳＵＳ３０４製の湿式粉砕機（商品名「アトライタ」）に、この水素化物を水で２０ｖｏｌ％のスラリーにしたものおよびジルコニアボールを入れ７時間湿式粉砕した。このスラリーを遠心沈降の後、デカンテーションして粉砕物を取得した。粉砕物を１３３Ｐａ（１Ｔｏｒｒ）、５０℃の条件で真空乾燥した。続いて、水素化ニオブ粉を１．３３×１０-2Ｐａ（１×１０-4Ｔｏｒｒ）、４００℃で１時間加熱し脱水素した。作製したニオブ粉の平均粒径は１．３μｍであった。
このニオブ粉に、平均粒径が約１μｍの酸化ジルコニウム、水素化ジルコニウム、またはジルコニウム金属のいずれか一種を任意の割合で混合した。得られたジルコニウム粉を含有するニオブ粉を４×１０-3Ｐａ（３×１０-5Ｔｏｒｒ）の真空下、１０００℃で造粒した。その後、造粒塊を解砕し平均粒径１９０μｍの造粒粉を得た。
得られたジルコニウムを含有するニオブ造粒粉を０．３ｍｍφのニオブ線と共に成形し、およそ０．３×０．１８×０．４５ｃｍの成形体（約０．１ｇ）を作製した。次にこれらの成形体を４×１０-3Ｐａ（３×１０-5Ｔｏｒｒ）の真空下、１２３０℃で３０分放置することにより焼結体を得た。得られた焼結体を、０．１％リン酸水溶液中で、８０℃の温度で２００分間、２０Ｖの電圧で化成することにより、表面に誘電体層を形成した。この後、３０％硫酸中での容量と、２０％リン酸水溶液中でのＬＣを各々測定した。結果を表４に示す。
【００５２】
【表４】
実施例２２〜２６：ジルコニウム含有一部窒化ニオブ粉焼結体
実施例１と同様な方法で作製したジルコニウムを１．２モル％含む平均粒径０．９μｍのジルコニウム含有ニオブ粉１０ｇをＳＵＳ３０４製の反応容器に入れ、３００℃で０．５時間〜２０時間窒素を導入し続けて、ジルコニウム含有ニオブ窒化物を得た。
この窒化物を熱電導度から窒素量を求めるＬＥＣＯ社製窒素量測定器を用いて窒素量を求め、別途測定した粉体の質量との比を窒化量としたところ、０．０２〜０．８９質量％であった。得られたジルコニウム含有ニオブ窒化物を実施例１と同様な操作で造粒、成形、焼結し、得られた焼結体を０．１％リン酸水溶液中で、８０℃の温度で２００分間、２０Ｖの電圧で化成することにより、表面に誘電体層を形成した。この後、３０％硫酸中での容量と、２０％リン酸水溶液中でのＬＣを各々測定した。結果を表５に示す。
【００５４】
【表５】
実施例２７〜２９：ジルコニウム含有ニオブ粉／ニオブ粉混合物焼結体
ニッケル製坩堝中、８０℃で充分に真空乾燥したフッ化ニオブ酸カリウム２０ｇにナトリウムをフッ化ニオブ酸カリウムの１０倍モル量を投入し、アルゴン雰囲気下１０００℃で２０時間還元反応を行った。反応後冷却させ、還元物を水洗した後に、９５％硫酸、水で順次洗浄した後に真空乾燥した。さらにシリカアルミナボール入りのアルミナポットのボールミルを用いて４０時間粉砕した後、粉砕物を５０％硝酸と１０％過酸化水素水の３：２（質量比）混合液中に浸漬撹拌した。その後、ｐＨが７になるまで充分水洗して不純物を除去し、真空乾燥した。作製したニオブ粉の平均粒径は１．２μｍであった。
得られたニオブ粉と、実施例１４と同様な方法で調製したジルコニウムを１０モル％含む平均粒径１．０μｍのジルコニウム含有ニオブ粉とを任意の割合で充分に混合し、実施例１４と同様な方法で造粒、成形、焼結を行って焼結体を得た。この焼結体について容量、ＬＣを各々測定した。結果を表６に示す。
【００５６】
実施例３０〜３２：一部窒化ジルコニウム含有ニオブ粉／ニオブ粉混合物焼結体
ニオブインゴット５０ｇをＳＵＳ３０４製の反応容器に入れ、４００℃で１２時間水素を導入し続けた。冷却後、水素化されたニオブ塊を鉄製ボールを入れたＳＵＳ３０４製のポットに入れ１０時間粉砕した。さらに、この粉砕物を前述したＳＵＳ３０４製反応器に入れ、再度、前述した条件で水素化した。次に、ＳＵＳ３０４製の湿式粉砕機に、この水素化物を水で２０ｖｏｌ％のスラリーにしたものおよびジルコニアボールを入れ６時間湿式粉砕した。このスラリーを遠心沈降の後、デカンテーションして粉砕物を取得した。粉砕物を１．３３×１０2Ｐａ（１Ｔｏｒｒ）、５０℃の条件で真空乾燥した。続いて、水素化ニオブ粉を１．３３×１０-2Ｐａ（１０-4Ｔｏｒｒ）、４００℃で１時間加熱し脱水素した。作製したニオブ粉の平均粒径は１．０μｍであった。
得られたニオブ粉と、実施例１４と同様な方法で調製したジルコニウムを１０モル％含む平均粒径０．９μｍのジルコニウム含有ニオブ粉とを任意の割合で充分に混合し、実施例２４と同様な方法で窒化物を得た後、造粒、成形、焼結を行って焼結体を得た。この焼結体について容量、ＬＣを各々測定した。結果を表６に示す。
【００５７】
【表６】
実施例３３〜３４：本発明によるコンデンサ素子の作製と評価
実施例３３は実施例１と、実施例３４は実施例１１と、それぞれ同様な方法で得た焼結体を各５０個用意した。
これらの焼結体を２０Ｖの電圧で、０．１％リン酸水溶液を用い、２００分間電解化成して、表面に誘電体酸化皮膜を形成した。次に、６０％硝酸マンガン水溶液に浸漬後２２０℃で３０分加熱することを繰り返して、誘電体酸化皮膜上に他方の電極層として二酸化マンガン層を形成した。その上に、カーボン層、銀ペースト層を順次積層した。次にリードフレームを載せた後、全体をエポキシ樹脂で封止して、チップ型コンデンサを作製した。このチップ型コンデンサの容量とＬＣ値の平均（ｎ＝各５０個）を表７に示す。
【００５９】
比較例８〜１０：ジルコニウムを含有しないニオブ粉焼結体によるコンデンサ素子
ニッケル製坩堝中、８０℃で充分に真空乾燥したフッ化ニオブ酸カリウム２０ｇにナトリウムをフッ化ニオブ酸カリウムの１０倍モル量を投入し、アルゴン雰囲気下１０００℃で２０時間還元反応を行った。反応後冷却させ、還元物を水洗した後に、９５％硫酸、水で順次洗浄した後に真空乾燥した。さらにシリカアルミナボール入りのアルミナポットのボールミルを用いて４０時間粉砕した後、粉砕物を５０％硝酸と１０％過酸化水素水の３：２（質量比）混合液中に浸漬撹拌した。その後、ｐＨが７になるまで充分水洗して不純物を除去し、真空乾燥した。作製したニオブ粉の平均粒径は１．３μｍであった。
この様にして得られた、ニオブ粉３０ｇをＳＵＳ３０４製の反応容器に入れ、３００℃で０．５〜４時間窒素を導入し続けて、ニオブ窒化物を得た。この窒化物を熱電導度から窒素量を求めるＬＥＣＯ社製窒素量測定器を用いて窒素量を求め、別途測定した粉体の質量との比を窒化量としたところ、０．０２〜０．３０質量％であった。
このニオブ窒化物を実施例１と同様の操作で造粒、成形、焼結を行って焼結体を得た。
得られた焼結体を用いて、実施例３３〜３４と同様に５０個のチップ型コンデンサを作製し、各物性を測定した。結果を表７に併せて示す。
【００６０】
【表７】
実施例３５〜３７：本発明によるコンデンサ素子の作製と評価
実施例３５は実施例７と、実施例３６は実施例１２と、実施例３７は実施例２４と、それぞれ同様な方法で得た焼結体を各５０個用意した。これらの焼結体を２０Ｖの電圧で、０．１％リン酸水溶液を用い、２００分間電解化成して、表面に誘電体酸化皮膜を形成した。
次に、誘電体酸化被膜の上に、過硫酸アンモニウム１０％水溶液とアンソラキノンスルホン酸０．５％水溶液の等量混合液を接触させた後、ピロール蒸気を触れさせる操作を少なくとも５回行うことによりポリピロールからなる他方の電極を形成した。その上に、カーボン層、銀ペースト層を順次積層した。次にリードフレームを載せた後、全体をエポキシ樹脂で封止して、チップ型コンデンサを作製した。このチップ型コンデンサの容量とＬＣ値の平均（ｎ＝各５０個）を表８に示す。
【００６２】
比較例１１〜１３：ジルコニウムを含有しないニオブ粉焼結体によるコンデンサ素子
ニオブインゴット５０ｇをＳＵＳ３０４製の反応容器に入れ、４００℃で１２時間水素を導入し続けた。冷却後、水素化されたニオブ塊を鉄製ボールを入れたＳＵＳ３０４製のポットに入れ１０時間粉砕した。さらに、この粉砕物を前述したＳＵＳ３０４製反応器に入れ、再度、前述した条件で水素化した。次に、ＳＵＳ３０４製の湿式粉砕機に、この水素化物を水で２０ｖｏｌ％のスラリーにしたものおよびジルコニアボールを入れ６時間湿式粉砕した。このスラリーを遠心沈降の後、デカンテーションして粉砕物を取得した。粉砕物を１．３３×１０2Ｐａ（１Ｔｏｒｒ）、５０℃の条件で真空乾燥した。続いて、水素化ニオブ粉を１．３３×１０-2Ｐａ（１×１０-4Ｔｏｒｒ）、４００℃で１時間加熱し脱水素した。作製したニオブ粉の平均粒径は１．０μｍであった。
ニオブ粉３０ｇをＳＵＳ３０４製の反応容器に入れ、３００℃で０．５〜３時間窒素を導入し続けて、ニオブ窒化物を得た。この窒化物を熱電導度から窒素量を求めるＬＥＣＯ社製窒素量測定器を用いて窒素量を求め、別途測定した粉体の質量との比を窒化量としたところ、０．０３〜０．２８質量％であった。
このニオブ窒化物を実施例１と同様の操作で造粒、成形、焼結を行って焼結体を得た。
得られた焼結体を用いて、実施例３５〜３７と同様に５０個のチップ型コンデンサを作製し、各物性を測定した。結果を表８に併せて示す。
【００６３】
【表８】
実施例３８〜３９：本発明によるコンデンサ素子の作製と評価
実施例３８は実施例８と、実施例３９は実施例１５と、それぞれ同様な方法で得た焼結体を各５０個用意した。これらの焼結体を２０Ｖの電圧で、０．１％リン酸水溶液を用い、２００分間電解化成して、表面に誘電体酸化皮膜を形成した。次に、３５％酢酸鉛水溶液と３５％過硫酸アンモニウム水溶液の１：１（容量比）混合液に浸漬後、４０℃で１時間反応させることを繰り返して、誘電体酸化皮膜上に他方の電極層として二酸化鉛と硫酸鉛の混合層を形成した。その上に、カーボン層、銀ペースト層を順次積層した。次にリードフレームを載せた後、全体をエポキシ樹脂で封止して、チップ型コンデンサを作製した。このチップ型コンデンサの容量とＬＣ値の平均（ｎ＝各５０個）を表９に示す。
【００６５】
【表９】
【発明の効果】
本発明の特定量のジルコニウムを含むニオブ及び／またはタンタルを主成分とするコンデンサ用粉体の焼結体から作製したコンデンサは、漏れ電流（ＬＣ）特性が良好でばらつきが少ない信頼性の大きな大容量のコンデンサとなる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal earth acid (mainly niobium, tantalum) powder capable of producing a capacitor having a large capacity per unit mass and good leakage current characteristics. More specifically, the present invention relates to niobium powder, tantalum powder and niobium-tantalum alloy powder containing a specific amount of zirconium, a sintered body using the powder, and a capacitor using the sintered body.
[0002]
[Background]
Capacitors used in electronic devices such as mobile phones and personal computers are desired to be small and have a large capacity. Among such capacitors, a tantalum capacitor is preferred because it has a large capacity for its size and good performance. Generally, a tantalum powder sintered body is used as an anode body of a tantalum capacitor. In order to increase the capacity of these tantalum capacitors, it is necessary to increase the mass of the sintered body or use a sintered body having a surface area increased by pulverizing tantalum powder.
[0003]
In the method of increasing the mass of the sintered body, the shape of the capacitor inevitably increases and does not satisfy the demand for downsizing. On the other hand, in the method of increasing the specific surface area by pulverizing tantalum powder, the pore diameter of the tantalum sintered body is reduced, and the number of closed pores is increased in the sintering stage, which makes it difficult to impregnate the cathode agent in the subsequent process. In order to solve these drawbacks, a method of reducing the number of closed holes in the sintering stage, a method of forming a capacitor using a material having a dielectric constant larger than that of tantalum, and the like can be considered. Niobium is a material having a large dielectric constant.
[0004]
In Japanese Patent Laid-Open No. 55-157226, an agglomerated powder of niobium fine powder (primary powder) having a particle size of 2.0 μm or less is pressed and sintered. A method for manufacturing a sintered element for a capacitor, which is cut and joined to a lead portion and then sintered again, is disclosed. However, this publication does not provide details on the characteristics of capacitors using sintered elements.
[0005]
In US Pat. No. 4,084,965, a niobium ingot is hydrogenated and pulverized to obtain a 5.1 μm niobium powder, and a capacitor using the niobium powder is disclosed. , Abbreviated as LC value) and large in practical use.
Japanese Laid-Open Patent Publication No. 10-224004 discloses that the LC value is improved by nitriding a part of niobium powder. However, when a high-capacity capacitor is produced from a niobium sintered body using niobium powder having a fine particle size, a capacitor having a specifically large LC value may appear.
[0006]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a powder for a capacitor capable of providing a capacitor having a large capacity per unit mass and a small leakage current value, a sintered body using the same, and a capacitor using the sintered body. There is.
[0007]
[Means for Solving the Problems]
As a result of earnestly examining the above-mentioned problems, the present inventor has included a specific amount of zirconium in niobium, tantalum, and niobium-tantalum alloy, so that even if sintering is performed using a powder having a small average particle diameter, The inventors have found that a large surface area can be maintained, and that when this sintered body is used as a capacitor, a stable capacitor having a large capacity and low LC can be obtained.
That is, the present invention relates to the following capacitor powder, a sintered body using the same, and a capacitor using the same.
[0008]
1. Capacitor powder containing zirconium and mainly containing niobium and / or tantalum.
2. 2. The capacitor powder according to 1 above, containing 0.01 to 15 atomic% of zirconium and mainly containing niobium and / or tantalum.
3. 3. The capacitor powder as described in 1 or 2 above, which contains niobium as a main component.
4). 3. The capacitor powder as described in 1 or 2 above, which mainly contains tantalum.
5. 2. The capacitor powder according to 1 above, comprising a niobium-tantalum alloy as a main component.
6). 6. The capacitor powder according to any one of 1 to 5 above, wherein the average particle size is 0.2 μm to 5 μm.
7). Specific surface area of 0.5-15m26. The capacitor powder according to any one of 1 to 5 above, which is / g.
8). 6. The capacitor powder according to any one of 1 to 5, wherein a part of niobium and / or tantalum is combined with at least one of nitrogen, carbon, boron, and sulfur.
9. 9. A capacitor powder having an average particle size of 20 to 500 [mu] m obtained by granulating the capacitor powder according to any one of 1 to 8 above.
10. 10. A sintered body using the capacitor powder according to any one of 1 to 9 above.
11. Specific surface area of 0.5-5m211. The sintered body according to 10 above, which is / g.
12 A capacitor comprising the sintered body according to 10 or 11 as one electrode, a dielectric formed on the surface of the sintered body, and the other electrode provided on the dielectric.
13. 13. The capacitor as described in 12 above, wherein the dielectric contains niobium oxide and / or tantalum oxide.
14 14. The capacitor as described in 13 above, wherein niobium oxide and / or tantalum oxide is formed by electrolytic oxidation.
15. 13. The capacitor according to 12 above, wherein the other electrode is at least one material selected from an electrolytic solution, an organic semiconductor, and an inorganic semiconductor.
16. 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, and The following general formula (1) or (2)
[Chemical 2]
16. The capacitor according to 15 above, which is at least one organic semiconductor selected from the group consisting of organic semiconductors mainly composed of a conductive polymer in which a dopant is doped in a polymer containing two or more repeating units represented by formula (1).
17. 17. The capacitor according to 16 above, wherein the organic semiconductor is at least one selected from polypyrrole, polythiophene, and substituted derivatives thereof.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to niobium powder, tantalum powder, and niobium-tantalum alloy powder for capacitors containing zirconium. Since these powder materials exhibit similar performance, the niobium powder is exemplified below. explain.
[0010]
The capacity of the capacitor is generally expressed by the following equation.
[Expression 1]
C = ε × (S / d)
(C: capacitance, ε: dielectric constant, S: specific area, d = distance between electrodes)
Here, since d = k × V (k: constant, V: formation voltage), C = ε × (S / (k × V)) and further C × V = (ε / k) × S are derived. It is burned. Therefore, the capacity can be increased by increasing the specific area (S).
[0011]
The first means for increasing the specific surface area of the sintered body used for the capacitor is to reduce the particle size of the powder used for the capacitor. In the present invention, the specific surface area of the powder can be increased to a practical level by making the average particle size of the primary particles of the niobium powder containing zirconium for producing the sintered body less than 5 μm.
[0012]
Table 1 shows the particle diameter and specific surface area of zirconium-containing niobium powder (pulverization method) produced by the inventors as an example.
[Table 1]
[0013]
As is clear from Table 1, the specific surface area of niobium powder containing zirconium can be increased by reducing the average particle diameter. However, if the average particle diameter of niobium powder containing zirconium is less than 0.2 μm, When a bonded body is produced, the pore diameter is reduced and the number of closed pores is increased, which makes it difficult to impregnate the cathode agent in a later step. As a result, the capacity cannot be increased, which is not suitable for practical use. On the other hand, when the average particle size is 5 μm or more, the specific surface area is small, and a large capacity cannot be obtained. Therefore, in the present invention, the average particle diameter of the niobium powder containing zirconium is preferably 0.2 μm or more and less than 5 μm.
[0014]
The second means of increasing the specific surface area of the sintered body used for the capacitor is that the specific surface area is small when a sintered body is formed by suppressing the formation of closed pores during sintering while using a powder having a small average particle diameter. It is not to be. Normally, the specific surface area can be maintained by lowering the sintering temperature, but when the sintering temperature is lowered, the strength of the sintered body is reduced and the steel tends to break.
In the present invention, a sintered body having a large specific surface area at a sintering temperature at which a required strength is obtained by containing a specific amount of zirconium in niobium powder, tantalum powder or niobium-tantalum alloy powder for a sintered body. It can be.
Table 2 shows the specific surface area of an example of the zirconium-containing niobium sintered body produced by the present inventor and the specific surface area of the niobium sintered body not containing zirconium.
[0015]
[Table 2]
As is apparent from Table 2, when sintering is performed at a temperature at which practical strength is obtained, the inclusion of zirconium can maintain a specific surface area about 1.5 times that of niobium powder not containing zirconium. it can.
[0017]
In addition, the niobium powder containing zirconium does not have a particularly large LC value even when the average particle size is reduced to produce a high-capacity sintered body. Although the details of the reason are unknown, it is estimated as follows.
Since niobium has a strong bonding force with oxygen elements, oxygen in the electrolytic oxide film is likely to diffuse to the inner niobium metal side. However, the sintered body in the present invention has an interaction such as that the underlying zirconium is bound to niobium, so that the oxygen in the electrolytic oxide film is less likely to bind to the niobium metal inside the sintered body, so It is considered that the diffusion of oxygen is suppressed, and as a result, the stability of the electrolytic oxide film can be maintained, and even in a capacitor having a fine particle size and a high capacity, an effect of reducing LC and reducing variation can be obtained.
[0018]
In the present invention, the content of zirconium in niobium powder for producing a sintered body is important, and is preferably 0.01 to 15 atomic%. 05-3 atomic percent is preferred.
If the zirconium content is too low, the above-described property that oxygen in the electrolytic oxide film tends to diffuse toward the inner niobium metal cannot be suppressed, and as a result, the stability of the electrolytic oxide film cannot be maintained. Thus, the effect of reducing LC cannot be obtained. Moreover, when there is too much, the niobium content in the niobium powder containing zirconium will decrease, and the capacity will decrease.
[0019]
The zirconium-containing niobium powder of the present invention used for producing a sintered body preferably has an average particle size of 0.2 μm to 5 μm.
Zirconium-containing niobium powder having such an average particle diameter can be produced by, for example, pulverizing a hydride such as a niobium-zirconium alloy ingot, pellets, and powder, followed by dehydrogenation. The average particle diameter of the zirconium-containing niobium powder can be adjusted to a desired range by appropriately changing the hydrogenation amount of the niobium-zirconium alloy, the pulverization time, the pulverizer, and the like.
Further, the zirconium content may be adjusted by mixing the zirconium-containing niobium powder obtained above with other niobium powder having an average particle diameter of 0.2 μm or more and less than 5 μm that does not contain zirconium.
Such niobium powder is, for example, a method of pulverizing niobium ingots, pellets, powder hydride and then dehydrogenating, a method of pulverizing potassium fluoride niobate reduced, sodium niobium oxide as an alkali metal, It can be obtained by a method of reduction with an alkaline earth metal, tantalum, niobium, aluminum, hydrogen, carbon or the like.
[0020]
The zirconium-containing niobium powder of the present invention may be a mixture of niobium powder not containing zirconium and metal zirconium or zirconium compound powder. Here, zirconium compounds include zirconium carbide, zirconium oxide (including stabilized zirconia), zirconium alkoxide, zirconium boride, zirconium nitride, zirconium sulfide, zirconium silicide, zirconium hydride, zirconium hydroxide, zirconium sulfate, zirconium silicate. Zirconium halide, zirconium oxyhalide, zirconium oxyacetate, zirconium oxynitrate and the like can be used, and these may be used alone or in combination of two or more.
[0021]
The zirconium-containing niobium powder of the present invention can also be obtained by a method of reducing a mixture of niobium oxide and zirconium oxide with an alkali metal, an alkaline earth metal, tantalum, niobium, aluminum, hydrogen, carbon, or the like.
[0022]
In order to further improve the leakage current value, the zirconium-containing niobium powder of the present invention may be one in which a part of the zirconium-containing niobium powder is bonded to at least one of nitrogen, carbon, boron, and sulfur. Zirconium-containing niobium nitride, zirconium-containing niobium carbide, zirconium-containing niobium boride, and zirconium-containing niobium sulfide, which are a combination of nitrogen, carbon, boron, and sulfur, may contain either of these alone, or two of these A combination of three or four types may be used.
[0023]
The amount of the bond (the total content of nitrogen, carbon, boron, and sulfur) varies depending on the shape of the zirconium-containing niobium powder, but it is 50 to 200,000 ppm with a powder having an average particle size of about 0.2 to 5 μm, 200 to 20000 ppm. If it is less than 50 ppm, the LC characteristic is not improved, and if it exceeds 200,000 ppm, the capacity characteristic is deteriorated and it is not suitable as a capacitor.
[0024]
Nitriding of the zirconium-containing niobium powder can be carried out by liquid nitriding, ion nitriding, gas nitriding, or a combination thereof, and among them, gas nitriding treatment is preferable because the apparatus is simple and easy to operate.
Gas nitriding can be performed by leaving the zirconium-containing niobium powder in a nitrogen gas atmosphere. The temperature of the nitriding atmosphere is 2000 ° C. or less, and the standing time is within several hours, whereby a zirconium-containing niobium powder having a target nitriding amount is obtained. Processing time can be shortened by processing at high temperature.
[0025]
Carbonization of the zirconium-containing niobium powder may be any of gas carbonization, solid phase carbonization, and liquid carbonization. For example, zirconium-containing niobium powder may be allowed to stand for several minutes to several tens of hours at 2000 ° C. or less under reduced pressure together with a carbon source such as a carbon material or an organic substance having carbon such as methane.
[0026]
The boride of the zirconium-containing niobium powder may be either gas boride or solid phase boride. For example, zirconium-containing niobium powder may be allowed to stand under reduced pressure at 2000 ° C. or lower for several minutes to several tens of hours together with a boron source of boron halide such as boron pellets or trifluoroboron.
[0027]
The sulfiding of the zirconium-containing niobium powder may be any of gas sulfiding, ionic sulfiding, and solid phase sulfiding. For example, the method of gas sulfiding in a sulfur gas atmosphere is achieved by leaving the zirconium-containing niobium powder in a sulfur atmosphere. The temperature of the sulfiding atmosphere is 2000 ° C. or less and the standing time is within several tens of hours to obtain a zirconium-containing niobium powder having a desired sulfiding amount. Further, the processing time can be shortened by processing at a higher temperature.
[0028]
The zirconium-containing niobium powder for capacitors for producing a sintered body may be obtained by granulating the above-mentioned zirconium-containing niobium primary powder into an appropriate shape, or after granulation, an ungranulated zirconium-containing niobium powder. Alternatively, an appropriate amount of niobium powder may be mixed and used.
Examples of granulation methods include, for example, a method in which ungranulated zirconium-containing niobium powder is left under high vacuum and heated to an appropriate temperature and then crushed, camphor, polyacrylic acid, polymethyl acrylate, polyvinyl alcohol, etc. And a method of pulverizing the mixture after mixing a suitable binder, a solvent such as acetone, alcohols, acetates, and water with ungranulated zirconium-containing niobium powder.
[0029]
By using the granulated zirconium-containing niobium powder, the pressure moldability when producing a sintered body is improved.
The average particle size of the granulated powder is preferably 20 to 500 μm. When the granulated powder has an average particle size of 20 μm or less, it is partially blocked and the fluidity to the mold is poor. If it is 500 μm or more, the corner portion of the molded body after pressure molding tends to be chipped. Furthermore, by setting the average particle size of the granulated powder to 60 to 250 μm, the sintered compact can be easily impregnated with the cathode agent when the capacitor is manufactured after the pressure-molded body is sintered.
[0030]
The zirconium-containing niobium sintered body for capacitors of the present invention is produced by molding and sintering the above-described zirconium-containing niobium powder or granulated zirconium-containing niobium powder. The method for producing the sintered body is not particularly limited. For example, after the zirconium-containing niobium powder is pressure-formed into a predetermined shape, 102-10-FiveIt is obtained by heating at 500 to 2000 ° C., preferably 900 to 1500 ° C., more preferably 900 to 1300 ° C. for several minutes to several hours at Pa.
[0031]
Next, manufacturing of the capacitor element will be described.
The capacitor of the present invention includes the above-described sintered body as one electrode, and is composed of a dielectric formed on the surface of the sintered body and the other electrode provided on the dielectric.
For example, when a lead wire having an appropriate shape and length made of a valve metal such as niobium or tantalum is prepared, and when niobium powder is sintered and pressure-molded, a part of the lead wire is inside the molded body. The lead wire is designed and assembled so that the lead wire becomes the lead of the sintered body.
[0032]
Examples of the dielectric of the capacitor include a dielectric made of tantalum oxide, niobium oxide, a polymer substance, a ceramic compound, and the like, and niobium oxide obtained by forming a zirconium-containing niobium sintered body in an electrolytic solution. A dielectric material mainly composed of is preferable. In order to form a zirconium-containing niobium electrode in an electrolytic solution, it is usually performed using a protonic acid aqueous solution, for example, a 0.1% phosphoric acid aqueous solution, a sulfuric acid aqueous solution or a 1% acetic acid aqueous solution, an adipic acid aqueous solution, or the like. When a zirconium-containing niobium electrode is formed in an electrolytic solution to obtain a niobium oxide dielectric, the capacitor of the present invention becomes an electrolytic capacitor and the zirconium-containing niobium electrode becomes an anode.
[0033]
The other electrode of the capacitor of the present invention is not particularly limited. For example, at least one material (compound) selected from an electrolytic solution, an organic semiconductor, and an inorganic semiconductor known in the aluminum electrolytic capacitor industry can be used. .
[0034]
Specific examples of the electrolyte include a mixed solution of dimethylformamide and ethylene glycol in which 5% by mass of isobutyltripropylammonium borotetrafluoride electrolyte is dissolved, propylene carbonate and ethylene glycol in which 7% by mass of tetraethylammonium borotetrafluoride is dissolved. Examples thereof include mixed solutions.
[0035]
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 (2)
[Chemical Formula 3]
The organic semiconductor which has as a main component the conductive polymer which doped the dopant in the polymer containing 2 or more of repeating units represented by these is mentioned. A well-known dopant can be used for a dopant without a restriction | limiting.
[0036]
Examples of the polymer containing two or more repeating units represented by the formula (1) or (2) include polyaniline, polyoxyphenylene, polyphenylene sulfide, polythiophene, polyfuran, polypyrrole, polymethylpyrrole, and substituted derivatives and copolymers thereof. A polymer etc. are mentioned. However, polypyrrole, polythiophene, and substituted derivatives thereof (for example, poly (3,4-ethylenedioxythiophene)) are preferable.
In this specification, “having a conductive polymer as a main component” means that a conductive polymer containing a component derived from impurities in a raw material monomer of an organic semiconductor can be included. It means that the molecule is a substantially active ingredient.
[0037]
Moreover, as a dopant, a sulfoquinone type dopant, an anthracene monosulfonic acid type dopant, and other various anionic dopants can be used. NO+, NO2 +Electron acceptor dopants such as salts may be used.
[0038]
Specific examples of the inorganic semiconductor include an inorganic semiconductor mainly composed of lead dioxide or manganese dioxide, and an inorganic semiconductor composed of iron trioxide.
Such semiconductors can be used alone, but may be used in combination of two or more.
[0039]
Conductivity of 10 as the organic semiconductor and inorganic semiconductor.-2S · cm-1-10ThreeS · cm-1If a capacitor in the range is used, the impedance value of the manufactured capacitor can be further reduced, and the capacitance at a high frequency can be further increased.
[0040]
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).
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 plating include nickel plating, copper plating, silver plating, and aluminum plating. Examples of the deposited metal include aluminum, nickel, copper, and silver.
[0041]
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 constitute a capacitor. The capacitor may have niobium or tantalum leads sintered together with a zirconium-containing niobium sintered body or later welded.
[0042]
The capacitor of the present invention having the above-described configuration can be made into a capacitor product for various purposes by, for example, a resin mold, a resin case, a metallic outer case, resin dipping, and a laminate film.
[0043]
When the other electrode is a liquid, the capacitor composed of the two electrodes and the dielectric is housed in, for example, a can electrically connected to the other electrode to form a capacitor. In this case, the electrode side of the zirconium-containing niobium sintered body is designed so as to be insulated from the can by insulating rubber or the like while being led out to the outside through the niobium or tantalum lead described above.
[0044]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to these examples. In addition, the capacity | capacitance of the sintered compact in each example, the leakage current value, the capacity | capacitance of the capacitor | condenser which carried out chip processing, and the measurement method of a leakage current value, and an evaluation method are as follows.
[0045]
(1) Capacity measurement of sintered body
At room temperature, the capacity at 120 Hz was measured by connecting an LCR measuring instrument manufactured by Hewlett-Packard Company between a sintered body immersed in 30% sulfuric acid and a tantalum electrode placed in a sulfuric acid solution. Capacity.
(2) Leakage current measurement of sintered body
At room temperature, a direct current voltage of 70% of the formation voltage (14V) at the time of forming the dielectric is applied for 3 minutes between the sintered body immersed in a 20% phosphoric acid aqueous solution and the electrode placed in the phosphoric acid aqueous solution. The current value measured after the application was continued was defined as the leakage current value (LC value) of the sintered body.
(3) Capacitance measurement
At room temperature, an LCR measuring instrument manufactured by Hewlett Packard was connected between the terminals of the manufactured chip, and the measured capacity at 120 Hz was defined as the capacity of the chip-processed capacitor.
(4) Capacitor leakage current measurement
At room temperature, a DC voltage close to about 1/3 to about 1/4 of the formation voltage at the time of dielectric fabrication among rated voltage values (2.5V, 4V, 6.3V, 10V, 16V, 25V, etc.). 3V), the current value measured after the voltage was continuously applied for 1 minute between the terminals of the manufactured chip was defined as the leakage current value of the capacitor processed into the chip.
[0046]
Example 1: Zirconium-containing niobium powder sintered body
A zirconium-containing niobium ingot containing 1 mol% of zirconium by arc melting was prepared using 92 g of niobium ingot and 1 g of zirconium powder. 50 g of this ingot was put in a reaction vessel made of SUS304, and hydrogen was continuously introduced at 400 ° C. for 10 hours. After cooling, the hydrogenated zirconium-containing niobium lump was placed in a SUS304 pot containing SUS balls and ground for 10 hours. Next, a SUS304 wet pulverizer in which the hydride was made into a 20 vol% slurry with water and zirconia balls were placed and wet pulverized for 7 hours. This slurry was centrifuged and decanted to obtain a pulverized product. The pulverized product was vacuum-dried at 133 Pa (1 Torr) and 50 ° C. Subsequently, the zirconium hydride-containing niobium powder was 1.33 × 10-2Pa (1 × 10-FourTorr) Pa for 1 hour at 400 ° C. for dehydrogenation. The produced zirconium-containing niobium powder had an average particle size of 1.0 μm, and the zirconium content measured by atomic absorption analysis was 1 mol%. The zirconium-containing niobium powder thus obtained was 4 × 10-3Pa (3 × 10-FiveGranulation at 1000 ° C. under a vacuum of Torr). Thereafter, the granulated mass was crushed to obtain a granulated powder having an average particle size of 120 μm.
The obtained zirconium-containing niobium granulated powder was molded together with a 0.3 mmφ niobium wire to produce a molded body (approximately 0.1 g) of approximately 0.3 × 0.18 × 0.45 cm. This molded body was 4 × 10-3Pa (3 × 10-FiveA sintered compact was obtained by leaving it at 1200 ° C. for 30 minutes under a vacuum of Torr). When the tensile strength of the niobium wire of the obtained sintered body was measured, it was 3 kg / cm.2(2.9 × 10FivePa) and had sufficient strength. Subsequently, the sintered body was formed in a 0.1% phosphoric acid aqueous solution at a temperature of 80 ° C. for 200 minutes at a voltage of 20 V, thereby forming a dielectric layer on the surface. Thereafter, the capacity in 30% sulfuric acid and the leakage current (hereinafter abbreviated as “LC”) in a 20% aqueous phosphoric acid solution were measured. The results are shown in Table 3.
[0047]
Examples 2 to 15: Zirconium-containing niobium / tantalum powder sintered body
A zirconium-containing niobium ingot, a zirconium-containing tantalum ingot, or a zirconium-containing niobium-tantalum ingot was produced by arc melting using zirconium powder and a niobium ingot, a tantalum ingot, or a niobium-tantalum alloy ingot at an arbitrary ratio.
Using the same apparatus as in Example 1 for 50 g of this ingot, the pulverization time was adjusted to obtain zirconium-containing niobium powder, zirconium-containing tantalum powder, and zirconium-containing niobium-tantalum powder having a desired particle size. Using each of these powders, a sintered body was produced in the same manner as in Example 1, and the capacity and LC were measured. The results are shown in Table 3.
[0048]
Comparative Examples 1 to 6: Niobium powder not containing zirconium, tantalum powder, niobium-tantalum alloy powder
By operating in the same manner as in Example 1, niobium powder, tantalum powder, and niobium-tantalum alloy powder not containing zirconium were prepared. A sintered body was produced using this powder in the same manner as in Example 1, and the capacity and LC were measured. The results are shown in Table 3.
[0049]
Comparative Examples 7 to 8: Niobium powder containing excessive zirconium
By operating in the same manner as in Example 1, zirconium-containing niobium powder containing 18.7 mol% and 24.6 mol% zirconium was prepared. A sintered body was produced using this powder in the same manner as in Example 1, and the capacity and LC were measured. The results are shown in Table 3.
[0050]
[Table 3]
Examples 16 to 21: Zirconium-containing niobium powder sintered body
100 g of niobium ingot was placed in a reaction vessel made of SUS304, and hydrogen was continuously introduced at 400 ° C. for 10 hours. After cooling, the hydrogenated niobium lump was placed in a SUS304 pot containing SUS balls and ground for 10 hours. Next, a SUS304 wet pulverizer (trade name “Attritor”) in which this hydride was made into a 20 vol% slurry with water and zirconia balls were placed and wet pulverized for 7 hours. This slurry was centrifuged and decanted to obtain a pulverized product. The pulverized product was vacuum-dried at 133 Pa (1 Torr) and 50 ° C. Subsequently, the niobium hydride powder was 1.33 × 10-2Pa (1 × 10-FourTorr) at 400 ° C. for 1 hour for dehydrogenation. The average particle size of the produced niobium powder was 1.3 μm.
Any one of zirconium oxide, zirconium hydride, and zirconium metal having an average particle diameter of about 1 μm was mixed with the niobium powder at an arbitrary ratio. The obtained niobium powder containing zirconium powder was 4 × 10-3Pa (3 × 10-FiveGranulation at 1000 ° C. under a vacuum of Torr). Thereafter, the granulated mass was crushed to obtain a granulated powder having an average particle size of 190 μm.
The obtained niobium granulated powder containing zirconium was molded together with a 0.3 mmφ niobium wire to produce a molded body (approximately 0.1 g) of approximately 0.3 × 0.18 × 0.45 cm. Next, these molded bodies were put into 4 × 10-3Pa (3 × 10-FiveA sintered compact was obtained by leaving it at 1230 ° C. for 30 minutes under a vacuum of Torr). The obtained sintered body was formed in a 0.1% phosphoric acid aqueous solution at a temperature of 80 ° C. for 200 minutes at a voltage of 20 V, thereby forming a dielectric layer on the surface. Thereafter, the volume in 30% sulfuric acid and the LC in 20% aqueous phosphoric acid solution were measured. The results are shown in Table 4.
[0052]
[Table 4]
Examples 22 to 26: Zirconium-containing partially sintered niobium nitride powder sintered body
10 g of zirconium-containing niobium powder having an average particle diameter of 0.9 μm and containing 1.2 mol% of zirconium prepared by the same method as in Example 1 is placed in a reaction vessel made of SUS304 and nitrogen at 300 ° C. for 0.5 to 20 hours. Then, zirconium-containing niobium nitride was obtained.
The nitrogen content of this nitride was determined using a nitrogen measuring device manufactured by LECO, which determines the nitrogen content from the thermal conductivity, and the ratio to the mass of the powder measured separately was taken as the nitriding content. It was 89 mass%. The obtained zirconium-containing niobium nitride was granulated, molded and sintered in the same manner as in Example 1. The obtained sintered body was placed in a 0.1% aqueous phosphoric acid solution at a temperature of 80 ° C. for 200 minutes. Then, a dielectric layer was formed on the surface by chemical conversion at a voltage of 20V. Thereafter, the volume in 30% sulfuric acid and the LC in 20% aqueous phosphoric acid solution were measured. The results are shown in Table 5.
[0054]
[Table 5]
Examples 27 to 29: Zirconium-containing niobium powder / niobium powder mixture sintered body
In a nickel crucible, 20 g of potassium fluoride niobate sufficiently vacuum-dried at 80 ° C. was charged with 10 times the amount of potassium fluoride niobate, and a reduction reaction was carried out at 1000 ° C. for 20 hours in an argon atmosphere. After the reaction, the reaction mixture was cooled, and the reduced product was washed with water, then washed with 95% sulfuric acid and water in that order, and then vacuum dried. Furthermore, after grind | pulverizing for 40 hours using the ball mill of the alumina pot containing a silica alumina ball | bowl, the ground material was immersed and stirred in the 3: 2 (mass ratio) liquid mixture of 50% nitric acid and 10% hydrogen peroxide solution. Thereafter, the product was sufficiently washed with water until the pH reached 7, to remove impurities, and vacuum dried. The average particle size of the produced niobium powder was 1.2 μm.
The obtained niobium powder and a zirconium-containing niobium powder having an average particle diameter of 1.0 μm and containing 10 mol% of zirconium prepared by the same method as in Example 14 were sufficiently mixed at an arbitrary ratio, and the same as in Example 14 The sintered body was obtained by granulating, forming and sintering by various methods. The volume and LC of this sintered body were measured. The results are shown in Table 6.
[0056]
Examples 30 to 32: Partially zirconium nitride-containing niobium powder / niobium powder mixture sintered body
50 g of niobium ingot was placed in a SUS304 reaction vessel, and hydrogen was continuously introduced at 400 ° C. for 12 hours. After cooling, the hydrogenated niobium lump was placed in a SUS304 pot containing iron balls and ground for 10 hours. Further, this pulverized product was put into the above-mentioned reactor made of SUS304 and hydrogenated again under the above-mentioned conditions. Next, a SUS304 wet pulverizer in which the hydride was made into a 20 vol% slurry with water and zirconia balls were placed and wet pulverized for 6 hours. This slurry was centrifuged and decanted to obtain a pulverized product. The pulverized product is 1.33 × 102It vacuum-dried on conditions of Pa (1 Torr) and 50 degreeC. Subsequently, the niobium hydride powder was 1.33 × 10-2Pa (10-FourTorr) at 400 ° C. for 1 hour for dehydrogenation. The average particle size of the produced niobium powder was 1.0 μm.
The obtained niobium powder and a zirconium-containing niobium powder having an average particle size of 0.9 μm and containing 10 mol% of zirconium prepared by the same method as in Example 14 were sufficiently mixed at an arbitrary ratio, and the same as in Example 24. After obtaining the nitride by various methods, granulation, molding and sintering were performed to obtain a sintered body. The volume and LC of this sintered body were measured. The results are shown in Table 6.
[0057]
[Table 6]
Examples 33 to 34: Production and evaluation of capacitor elements according to the present invention
In Example 33, 50 sintered bodies obtained by the same method as Example 1 and Example 34, respectively, were prepared.
These sintered bodies were electrolyzed for 200 minutes using a 0.1% phosphoric acid aqueous solution at a voltage of 20 V to form a dielectric oxide film on the surface. Next, after being immersed in a 60% aqueous manganese nitrate solution, heating at 220 ° C. for 30 minutes was repeated to form a manganese dioxide layer on the dielectric oxide film as the other electrode layer. A carbon layer and a silver paste layer were sequentially laminated thereon. Next, after the lead frame was mounted, the whole was sealed with an epoxy resin to produce a chip capacitor. Table 7 shows the average capacitance and LC value (n = 50 for each) of this chip capacitor.
[0059]
Comparative Examples 8 to 10: Capacitor elements using a sintered niobium powder containing no zirconium
In a nickel crucible, 20 g of potassium fluoride niobate sufficiently vacuum-dried at 80 ° C. was charged with 10 times the amount of potassium fluoride niobate, and a reduction reaction was carried out at 1000 ° C. for 20 hours in an argon atmosphere. After the reaction, the reaction mixture was cooled, and the reduced product was washed with water, then washed with 95% sulfuric acid and water in that order, and then vacuum dried. Furthermore, after grind | pulverizing for 40 hours using the ball mill of the alumina pot containing a silica alumina ball | bowl, the ground material was immersed and stirred in the 3: 2 (mass ratio) liquid mixture of 50% nitric acid and 10% hydrogen peroxide solution. Thereafter, the product was sufficiently washed with water until the pH reached 7, to remove impurities, and vacuum dried. The average particle size of the produced niobium powder was 1.3 μm.
30 g of the niobium powder thus obtained was placed in a reaction vessel made of SUS304, and nitrogen was continuously introduced at 300 ° C. for 0.5 to 4 hours to obtain niobium nitride. The nitrogen content of this nitride was determined using a nitrogen measuring device manufactured by LECO, which determines the nitrogen content from the thermal conductivity, and the ratio to the mass of the powder measured separately was taken as the nitriding content. It was 30% by mass.
This niobium nitride was granulated, molded and sintered in the same manner as in Example 1 to obtain a sintered body.
Using the obtained sintered body, 50 chip capacitors were produced in the same manner as in Examples 33 to 34, and each physical property was measured. The results are also shown in Table 7.
[0060]
[Table 7]
Examples 35 to 37: Production and evaluation of capacitor elements according to the present invention
Example 35 prepared Example 7, Example 36 prepared Example 12, Example 37 prepared Example 24, and each Example 50 prepared 50 sintered bodies obtained in the same manner. These sintered bodies were electrolyzed for 200 minutes using a 0.1% phosphoric acid aqueous solution at a voltage of 20 V to form a dielectric oxide film on the surface.
Next, after contacting an equal volume of 10% aqueous solution of ammonium persulfate and 0.5% aqueous solution of anthoraquinone sulfonic acid on the dielectric oxide film, an operation of touching pyrrole vapor is performed at least 5 times. Thus, the other electrode made of polypyrrole was formed. A carbon layer and a silver paste layer were sequentially laminated thereon. Next, after the lead frame was mounted, the whole was sealed with an epoxy resin to produce a chip capacitor. Table 8 shows the average of the capacitance and the LC value (n = 50 each) of this chip type capacitor.
[0062]
Comparative Examples 11 to 13: Capacitor elements using a sintered niobium powder containing no zirconium
50 g of niobium ingot was placed in a SUS304 reaction vessel, and hydrogen was continuously introduced at 400 ° C. for 12 hours. After cooling, the hydrogenated niobium lump was placed in a SUS304 pot containing iron balls and ground for 10 hours. Further, this pulverized product was put into the above-mentioned reactor made of SUS304 and hydrogenated again under the above-mentioned conditions. Next, a SUS304 wet pulverizer in which the hydride was made into a 20 vol% slurry with water and zirconia balls were placed and wet pulverized for 6 hours. This slurry was centrifuged and decanted to obtain a pulverized product. The pulverized product is 1.33 × 102It vacuum-dried on conditions of Pa (1 Torr) and 50 degreeC. Subsequently, the niobium hydride powder was 1.33 × 10-2Pa (1 × 10-FourTorr) at 400 ° C. for 1 hour for dehydrogenation. The average particle size of the produced niobium powder was 1.0 μm.
30 g of niobium powder was put in a reaction vessel made of SUS304, and nitrogen was continuously introduced at 300 ° C. for 0.5 to 3 hours to obtain niobium nitride. The nitrogen content of this nitride was determined using a nitrogen measuring device manufactured by LECO, which determines the nitrogen content from the thermal conductivity, and the ratio to the mass of the powder measured separately was taken as the nitridation content. It was 28 mass%.
This niobium nitride was granulated, molded and sintered in the same manner as in Example 1 to obtain a sintered body.
Using the obtained sintered body, 50 chip-type capacitors were produced in the same manner as in Examples 35 to 37, and each physical property was measured. The results are also shown in Table 8.
[0063]
[Table 8]
Examples 38 to 39: Production and evaluation of capacitor elements according to the present invention
In Example 38, Example 8 was prepared, and in Example 39, Example 15 and 50 sintered bodies obtained in the same manner were prepared. These sintered bodies were electrolyzed for 200 minutes using a 0.1% phosphoric acid aqueous solution at a voltage of 20 V to form a dielectric oxide film on the surface. Next, after being immersed in a 1: 1 (volume ratio) mixture of 35% lead acetate aqueous solution and 35% ammonium persulfate aqueous solution, the reaction is repeated at 40 ° C. for 1 hour, and the other electrode layer is formed on the dielectric oxide film. As a mixed layer of lead dioxide and lead sulfate. A carbon layer and a silver paste layer were sequentially laminated thereon. Next, after the lead frame was mounted, the whole was sealed with an epoxy resin to produce a chip capacitor. Table 9 shows the average of the capacitance and LC value of this chip capacitor (n = 50 each).
[0065]
[Table 9]
【The invention's effect】
Capacitors produced from sintered powders for capacitors mainly composed of niobium and / or tantalum containing a specific amount of zirconium according to the present invention have large leakage current (LC) characteristics and small variations. Capacitance capacitor.
Claims (12)
で示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導電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る少なくとも１種の有機半導体である請求項１０に記載のコンデンサ。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, and The following general formula (1) or (2)
The capacitor according to claim 10 , wherein the capacitor is at least one organic semiconductor 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 formula (1).
Priority Applications (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000366039A JP4683512B2 (en) | 2000-11-30 | 2000-11-30 | Capacitor powder, sintered body using the same, and capacitor using the same |
| AU1851002A AU1851002A (en) | 2000-11-30 | 2001-11-30 | Powder for capacitor, sintered body thereof and capacitor using the sintered body |
| AT01998979T ATE336073T1 (en) | 2000-11-30 | 2001-11-30 | CAPACITOR POWDER, SINTERED BODY AND CAPACITOR WITH THIS SINTERED BODY |
| PCT/JP2001/010484 WO2002045106A2 (en) | 2000-11-30 | 2001-11-30 | Powder for capacitor, sintered body thereof and capacitor using the sintered body |
| AU2002218510A AU2002218510B2 (en) | 2000-11-30 | 2001-11-30 | Powder for capacitor, sintered body thereof and capacitor using the sintered body |
| US10/433,047 US6824586B2 (en) | 2000-11-30 | 2001-11-30 | Powder for capacitor, sintered body thereof and capacitor using the sintered body |
| EP01998979A EP1340235B1 (en) | 2000-11-30 | 2001-11-30 | Powder for capacitor, sintered body thereof and capacitor using the sintered body |
| DE60122205T DE60122205T2 (en) | 2000-11-30 | 2001-11-30 | CAPACITOR POWDER, SINTER BODY AND CONDENSER WITH THIS SINTER BODY |
| CNB01819611XA CN100401436C (en) | 2000-11-30 | 2001-11-30 | Powder for capacitor, sintered body thereof and capacitor using sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000366039A JP4683512B2 (en) | 2000-11-30 | 2000-11-30 | Capacitor powder, sintered body using the same, and capacitor using the same |
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| Publication Number | Publication Date |
|---|---|
| JP2002173371A JP2002173371A (en) | 2002-06-21 |
| JP4683512B2 true JP4683512B2 (en) | 2011-05-18 |
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| JP2000366039A Expired - Fee Related JP4683512B2 (en) | 2000-11-30 | 2000-11-30 | Capacitor powder, sintered body using the same, and capacitor using the same |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP4683512B2 (en) |
| CN (1) | CN100401436C (en) |
| AT (1) | ATE336073T1 (en) |
| DE (1) | DE60122205T2 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19953946A1 (en) * | 1999-11-09 | 2001-05-10 | Starck H C Gmbh Co Kg | Capacitor powder |
| EP1505611B9 (en) * | 2003-07-22 | 2012-12-05 | H.C. Starck GmbH | Method of making capacitors |
| US7729104B2 (en) | 2004-04-15 | 2010-06-01 | Jfe Mineral Company, Ltd. | Tantalum powder and solid electrolyte capacitor including the same |
| US8379370B2 (en) | 2007-03-08 | 2013-02-19 | Rohm Co., Ltd. | Composite material, capacitor using the same, and their production methods |
| US8107218B2 (en) * | 2009-06-02 | 2012-01-31 | Micron Technology, Inc. | Capacitors |
| US20160196925A1 (en) * | 2013-08-30 | 2016-07-07 | Showa Denko K.K. | Tungsten powder and anode body of capacitor |
| CN103934452B (en) * | 2014-05-12 | 2016-07-06 | 宁夏东方钽业股份有限公司 | A kind of dough method of superelevation specific volume tantalum powder and the tantalum powder prepared by the method |
| KR102220538B1 (en) | 2014-09-23 | 2021-02-24 | 경희대학교 산학협력단 | Electrode including organic semiconducting material, method for manufacturing electrode and supercapacitor including the electrode |
| US10290430B2 (en) * | 2014-11-24 | 2019-05-14 | Avx Corporation | Wet Electrolytic Capacitor for an Implantable Medical Device |
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| JPS55157226A (en) * | 1979-05-25 | 1980-12-06 | Matsushita Electric Ind Co Ltd | Method of manufacturing sintered element for capacitor |
| JPH0513282A (en) * | 1991-06-29 | 1993-01-22 | Nippon Chemicon Corp | Cathode material for electrolytic capacitor |
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- 2000-11-30 JP JP2000366039A patent/JP4683512B2/en not_active Expired - Fee Related
-
2001
- 2001-11-30 DE DE60122205T patent/DE60122205T2/en not_active Expired - Lifetime
- 2001-11-30 AT AT01998979T patent/ATE336073T1/en not_active IP Right Cessation
- 2001-11-30 CN CNB01819611XA patent/CN100401436C/en not_active Expired - Fee Related
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3849124A (en) * | 1969-12-05 | 1974-11-19 | Norton Co | Capacitor powder |
| US4084965A (en) * | 1977-01-05 | 1978-04-18 | Fansteel Inc. | Columbium powder and method of making the same |
| JPS55157226A (en) * | 1979-05-25 | 1980-12-06 | Matsushita Electric Ind Co Ltd | Method of manufacturing sintered element for capacitor |
| JPH0513282A (en) * | 1991-06-29 | 1993-01-22 | Nippon Chemicon Corp | Cathode material for electrolytic capacitor |
| JPH10242004A (en) * | 1997-02-28 | 1998-09-11 | Showa Denko Kk | Capacitor |
| WO2000067936A1 (en) * | 1998-05-06 | 2000-11-16 | H.C. Starck, Inc. | Metal powders produced by the reduction of the oxides with gaseous magnesium |
| WO2000049633A1 (en) * | 1999-02-16 | 2000-08-24 | Showa Denko K.K. | Niobium powder, niobium sintered body, capacitor comprised of the sintered body, and method for manufacturing the capacitor |
| WO2000075943A1 (en) * | 1999-06-09 | 2000-12-14 | Showa Denko Kabushiki Kaisha | Electrode material for capacitor and capacitor using the same |
Also Published As
| Publication number | Publication date |
|---|---|
| ATE336073T1 (en) | 2006-09-15 |
| CN1478287A (en) | 2004-02-25 |
| JP2002173371A (en) | 2002-06-21 |
| DE60122205T2 (en) | 2007-07-05 |
| DE60122205D1 (en) | 2006-09-21 |
| CN100401436C (en) | 2008-07-09 |
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