JP4367827B2 - Niobium alloy, sintered body thereof, and capacitor using the same - Google Patents

Description

【００３４】
表１に示した平均粒径（Ｄ₅₀；μｍ）は、粒度分布測定器（マイクロトラック社製、商品名「マイクロトラック」）を用いて測定した値であり（Ｄ₅₀値とは、累積質量％が５０質量％に相当する粒径値を表す。）、比表面積はＢＥＴ法で測定した値である。
【００３５】
前記ニオブ合金粉の平均粒径が５μｍを越えると大きなコンデンサ容量を達成できない。また、平均粒径を0.05μｍ未満にすると、該粉体から焼結体を作製した場合、細孔径が小さく、また閉鎖孔が多くなり、後述する陰極剤の含浸が難しくなる傾向にある。そのため、結果としてコンデンサ容量を大きくすることが難しく、コンデンサ用のニオブ合金焼結体として余り適さない。
【００３６】
以上の点から、本発明においては、好ましくはニオブ合金粉として0.05〜５μｍの平均粒径のものを使用することで大きなコンデンサ容量を達成することができる。
【００３７】
本発明のニオブ合金は、少なくとも0.5ｍ²／ｇのＢＥＴ比表面積を有する粉体が好ましく、さらに少なくとも１ｍ²／ｇのＢＥＴ比表面積を有する粉体が好ましく、さらにまた、少なくとも２ｍ²／ｇのＢＥＴ比表面積を有する粉体が好ましい。また、本発明のニオブ粉は、0.5〜４０ｍ²／ｇのＢＥＴ比表面積を有する粉体が好ましく、さらに１〜２０ｍ²／ｇのＢＥＴ比表面積を有する粉体が特に好ましい。
焼結体を作成するために用いられるジルコニウム−一窒化二ニオブ結晶を含有するニオブ合金粉は、前述したように0.5〜４μｍの平均粒径が特に好ましい。
【００３８】
以下、主としてジルコニウム−一窒化二ニオブ結晶を含有するニオブ合金、またはネオジム−一窒化二ニオブ結晶を含有するニオブ合金を例に挙げて本発明を説明するが、本発明はこれに限定されず、以下の内容は、周期律表の２族乃至１６族からなる群から選ばれる少なくとも１種の元素を合金成分として含有するニオブ合金に、さらに一窒化二ニオブ結晶を含有するニオブ合金の場合にも適用される。
【００３９】
前述の平均粒径を有するジルコニウム−一窒化二ニオブ結晶を含有するニオブ合金粉は、たとえばジルコニウム−ニオブ合金インゴット、ペレット、粉などの水素化物の粉砕によって得られたジルコニウムを含有するニオブ水素化合金や、この水素化合金を脱水素化したジルコニウムを含有するニオブ合金粉に、平均粒径が0.05μｍ〜５μｍの一窒化二ニオブ結晶及び／または一窒化二ニオブ結晶の水素化物を混合することによって得られる。この混合は、室温以下の温度で不活性ガス（Ａｒ、Ｈｅ、窒素など）雰囲気下、粉体同士を混合しても良いし、水、メタノール、ジクロロエタン、トルエンなどの適当な溶媒を用いて混合しても良い。適当な溶媒を用いた場合、減圧下、５０℃以下の温度で溶媒を留去することが望ましい。得られた混合粉を用いて焼結体を作成しても良いし、この混合粉を還元雰囲気下（例えば、Ａｒ、Ｈｅ、Ｈ₂などの雰囲気下）、１０^-3〜１０⁶Ｐａ（パスカル）の圧力で２００℃〜1500℃の温度に１分から１００時間曝して、必要とあれば解砕などの工程を用いて作成したこの混合粉を用いて焼結体を作成しても良い。
【００４０】
また、ジルコニウム−一窒化二ニオブ結晶を含有するニオブ合金の他の製造方法としては、たとえば、ジルコニウム−ニオブ合金インゴット、ペレット、粉などの水素化物の粉砕によって得られた、平均粒径が0.5〜５μｍのジルコニウムを含有するニオブ水素化合金粉や、この水素化合金を脱水素化したジルコニウムを含有するニオブ合金粉を窒素雰囲気下、１０²〜１０⁶Ｐａの圧力で、２００℃〜７５０℃の温度、好ましくは３００℃〜６００℃の温度に１分〜１００時間曝すことで窒素化した後、更にＡｒ、Ｈｅなどの不活性ガス雰囲気下、１０²〜１０⁶Ｐａの圧力で、８００℃〜1500℃の温度、好ましくは８５０℃〜1100℃の温度に１分〜１００時間曝すことで窒化したニオブを一窒化二ニオブ結晶に変化させることにより、ジルコニウム−一窒化二ニオブ結晶を含有するニオブ合金を製造しても良い。この方法は、ニオブ合金の替わりに焼結後の焼結体に適用してもよい。
【００４１】
更に、他の製造方法として、ニオブインゴット、ペレット状の水素化物の粉砕による方法、及びこの水素化ニオブ粉を脱水素する方法、あるいはフッ化ニオブ酸カリウムのナトリウム還元物の粉砕による方法、あるいは酸化ニオブの水素、炭素、マグネシウム、アルミニウム、セリウム、ランタン、ミッシュメタル等の少なくとも１種を使用して還元した還元物の粉砕などの方法によって製造されたニオブ粉または水素化ニオブ粉を用いて、窒素雰囲気下、１０²〜１０⁶Ｐａの圧力で、２００℃〜７５０℃の温度、好ましくは３００℃〜６００℃の温度に１分〜１００時間曝すことで窒素化した後、更にＡｒ、Ｈｅなどの不活性ガス雰囲気下、１０²〜１０⁶Ｐａの圧力で、８００℃〜1500℃の温度、好ましくは８５０℃〜1100℃の温度に１分〜１００時間曝すことで窒化したニオブを一窒化二ニオブ結晶に変化させ、必要とあれば解砕などの工程を用いて一窒化二ニオブ結晶を含有するニオブ粉を得たのち、ネオジムの粉体、ネオジムの水素化物、酸化物、硫化物、ホウ化物、炭化物、硫酸塩、ハロゲン化塩、硝酸塩、有機酸塩、錯塩などを混合しても良い。
【００４２】
このようにして得たネオジム−一窒化二ニオブ結晶を含有するニオブ合金に平均粒径が0.05μｍ〜５μｍのネオジム含有ニオブ粉及び／またはニオブ粉を混合して、一窒化二ニオブ結晶の含有量及び／またはネオジムの含有量を調整しても良いし、更に平均粒径が0.05μｍ〜５μｍの一窒化二ニオブ結晶を混合してネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉中の一窒化二ニオブ結晶の含有量を調整しても良い。
【００４３】
本発明のコンデンサ用ネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉は、前述したネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉を適当な形状に造粒した後、使用してもよいし、造粒後に未造粒のニオブ粉を適量混合して使用してもよい。
【００４４】
［造粒物］
造粒の方法として、例えば、未造粒のネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉を高減圧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、あるいは造粒したネオジム−一窒化二ニオブ結晶を含有するニオブ合金を混合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、あるいは造粒したネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉を混合したのち高減圧下焼結し、添加したバインダーと溶媒を蒸発、昇華または熱分解し気体にすることにより除去したのち焼結したネオジム−一窒化二ニオブ結晶を含有するニオブ合金塊を解砕する方法、酸化バリウム、酸化マグネシウムなどとアセトン、アルコール類、酢酸エステル類、水などの溶媒と未造粒、あるいは造粒したネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉を混合したのち高減圧下焼結し、解砕した後、硝酸、塩酸などの酸溶液やキレート剤を含む溶液で酸化バリウム、酸化マグネシウムなどを溶解することにより除去する方法等が挙げられる。
【００４５】
このようにして造粒したネオジム−一窒化二ニオブ結晶を含有するニオブ合金は、焼結体を製造する際の加圧成形性を向上させる。この場合、造粒粉の平均粒径は、１０〜５００μｍが好ましい。造粒粉の平均粒径が１０μｍ以下では部分的にブロッキングを起こし、金型への流動性が悪くなる。５００μｍ以上では加圧成形後の成形体が欠けやすい。さらに、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の含浸がしやすいことから、造粒粉の平均粒径は、３０μｍ〜２５０μｍが特に好ましい。このように造粒したネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉は、安息角が６０度以下で極めて流れやすい。また表面が一部酸化され、その酸素含有量は、3000ｐｐｍ〜100000ｐｐｍであり、装置や使用する原料などから混入する不純物としてのＦｅ、Ｃｒ、Ｎｉ、Ｂａ、Ｍｇ、Ｓｉ、Ａｌ、炭素などの量は数１００ｐｐｍ以下であった。
【００４６】
本発明のコンデンサ用ネオジム−一窒化二ニオブ結晶を含有するニオブ合金焼結体は、前述したネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉あるいは造粒したネオジム−一窒化二ニオブ結晶を含有するニオブ合金造粒粉を焼結して製造する。焼結体の製造方法は特に限定されるものではないが、例えば、ネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉を所定の形状に加圧成形した後に１０^-5〜１０²Ｐａで数分〜数十時間、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。
【００４７】
このようにして得られたネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉、造粒粉、焼結体の漏れ電流値をさらに改善するために、ネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉、造粒粉、焼結体の一部を窒化、ホウ化、炭化、硫化、または複数のこれらによる処理をしてもよい。得られたネオジム−一窒化二ニオブ結晶を含有するニオブ合金の窒化物、ネオジム−一窒化二ニオブ結晶を含有するニオブ合金のホウ化物、ネオジム−一窒化二ニオブ結晶を含有するニオブ合金の炭化物、ネオジム−一窒化二ニオブ結晶を含有するニオブ合金の硫化物、はいずれを含有してもよく、また、これらの２種以上の組み合わせであってもよい。
【００４８】
その結合量、すなわち、窒素、ホウ素、炭素、硫黄の含有量の総和は、ネオジム−一窒化二ニオブ結晶を含有するニオブ合金の形状にもよって変わるが、０ｐｐｍより多く200000ｐｐｍ以下、好ましくは５０ｐｐｍ〜100000ｐｐｍ、さらに好ましくは、２００ｐｐｍ〜20000ｐｐｍである。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。
【００４９】
ネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉、造粒粉、焼結体の窒化方法は、液体窒化、イオン窒化、ガス窒化などのうち、何れかあるいは、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は、装置が簡便で操作が容易なため好ましい。例えば、窒素ガス雰囲気によるガス窒化の方法は、前記ネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉、造粒粉、焼結体を窒素雰囲気中に放置することにより達成される。窒化する雰囲気の温度は、2000℃以下、放置時間は１００時間以内で目的とする窒化量のネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉、造粒粉、焼結体が得られる。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。
【００５０】
ネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉、造粒粉、焼結体のホウ化方法は、ガスホウ化、固相ホウ化いずれであってもよい。例えば、ネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉、造粒粉、焼結体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共に、減圧下、2000℃以下で１分〜１００時間程度、放置しておけばよい。
【００５１】
ネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉、造粒粉、焼結体の炭化は、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、ネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉、造粒粉、焼結体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、2000℃以下で１分〜１００時間程度放置しておけばよい。
【００５２】
ネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉、造粒粉、焼結体の硫化方法は、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、前記ネオジム−一窒化二ニオブ結晶を含有するニオブ合金粉、造粒粉、焼結体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１００時間以内で目的とする硫化量のニオブ粉、造粒粉、焼結体が得られる。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。
【００５３】
次に、コンデンサ素子の製造について説明する。
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、適当な形状及び長さを有するリードワイヤーを用意し、これを前述したニオブ粉の加圧成形時にリードワイヤーの一部が成形体の内部に挿入させるように一体成形して、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組み立て設計する。
【００５４】
前述した焼結体を一方の電極とし、対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。ここでコンデンサの誘電体として、酸化ニオブを主体とする誘電体が好ましく挙げられる。酸化ニオブを主体とする誘電体は、例えば、一方の電極であるネオジム−一窒化二ニオブ結晶を含有するニオブ合金焼結体を電解液中で化成することによって得られる。ネオジム−一窒化二ニオブ結晶を含有するニオブ合金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。ネオジム−一窒化二ニオブ結晶を含有するニオブ合金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ネオジム−一窒化二ニオブ結晶を含有するニオブ合金電極が陽極となる。
【００５５】
本発明のコンデンサにおいて、ニオブ焼結体の対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、有機半導体及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。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などが挙げられる。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、あるいは下記一般式（１）または一般式（２）で表される繰り返し単位を含む導電性高分子が挙げられる。
【００５６】
【化１】

【００５７】
式中、Ｒ¹〜Ｒ⁴はそれぞれ独立して水素原子、炭素数１乃至１０の直鎖上もしくは分岐状の飽和もしくは不飽和のアルキル基、アルコキシ基あるいはアルキルエステル基、またはハロゲン原子、ニトロ基、シアノ基、１級、２級もしくは３級アミノ基、ＣＦ₃基、フェニル基及び置換フェニル基からなる群から選ばれる一価基を表わす。Ｒ¹とＲ²及びＲ³とＲ⁴の炭化水素鎖は互いに任意の位置で結合して、かかる基により置換を受けている炭素原子と共に少なくとも１つ以上の３〜７員環の飽和または不飽和炭化水素の環状構造を形成する二価鎖を形成してもよい。前記環状結合鎖には、カルボニル、エーテル、エステル、アミド、スルフィド、スルフィニル、スルホニル、イミノの結合を任意の位置に含んでもよい。Ｘは酸素、硫黄または窒素原子を表し、Ｒ⁵はＸが窒素原子の時のみ存在して、独立して水素または炭素数１乃至１０の直鎖上もしくは分岐状の飽和もしくは不飽和のアルキル基を表す。
【００５８】
さらに、本発明においては前記一般式（１）または一般式（２）のＲ¹〜Ｒ⁴は、好ましくは、それぞれ独立して水素原子、炭素数１乃至６の直鎖上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アルコキシ基を表し、Ｒ¹とＲ²及びＲ³とＲ⁴は互いに結合して環状になっていてもよい。
【００５９】
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導電性高分子は、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導電性高分子が挙げられる。
【００６０】
【化２】

【００６１】
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。
【００６２】
このような化学構造を含む導電性高分子は、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。
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も、または２種以上組み合わせて使用してもよい。
【００６３】
一般式（１）または一般式（２）で表される繰り返し単位を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、及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。
【００６４】
上記有機半導体及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。
【００６５】
前記導電性高分子層を製造する方法としては、例えばアニリン、チオフェン、フラン、ピロール、メチルピロールまたはこれらの置換誘導体の重合性化合物を、脱水素的２電子酸化の酸化反応を充分行わせ得る酸化剤の作用で重合する方法が採用される。重合性化合物（モノマー）からの重合反応は、例えばモノマーの気相重合、溶液重合等があり、誘電体を有するニオブ焼結体の表面に形成される。導電性高分子が溶液塗布可能な有機溶媒可溶性のポリマーの場合には、表面に塗布して形成する方法が採用される。
【００６６】
溶液重合による好ましい製造方法の１つとして、誘電体層を形成したニオブ焼結体を、酸化剤を含む溶液（溶液１）に浸漬し、次いでモノマー及びドーパントを含む溶液（溶液２）に浸漬して重合し、該表面に導電性高分子層を形成得する方法が例示される。また、前記焼結体を、溶液２に浸漬した後で溶液１に浸漬してもよい。また、前記溶液２においては、ドーパントを含まないモノマー溶液として前記方法に使用してもい。また、ドーパントを使用する場合、酸化剤を含む溶液に共存させて使用してもよい。
【００６７】
このような重合工程操作を、誘電体を有する前記ニオブ焼結体に対して１回以上、好ましくは３〜２０回繰り返すことによって緻密で層状の導電性高分子層を容易に形成することができる。
【００６８】
本発明のコンデンサの製造方法においては、酸化剤はコンデンサ性能に悪影響を及ぼすことなく、その酸化剤の還元体がドーパントになって導電性高分子の電動度を向上させ得る酸化剤であればよく、工業的に安価で製造上取り扱いの容易な化合物が好まれる。
【００６９】
このような酸化剤としては、具体的には、例えばＦｅＣｌ₃やＦｅＣｌＯ₄、Ｆｅ（有機酸アニオン）塩等のＦｅ（III）系化合物類、または無水塩化アルミニウム／塩化第一銅、アルカリ金属過硫酸塩類、過硫酸アンモニウム塩類、過酸化物類、過マンガン酸カリウム等のマンガン類、２，３−ジクロロ−５，６−ジシアノ−１，４−ベンゾキノン（ＤＤＱ）、テトラクロロ−１，４−ベンゾキノン、テトラシアノ−１，４−ベンゾキノン等のキノン類、よう素、臭素等のハロゲン類、過酸、硫酸、発煙硫酸、三酸化硫黄、クロロ硫酸、フルオロ硫酸、アミド硫酸等のスルホン酸、オゾン等及びこれら複数の酸化剤の組み合わせが挙げられる。
【００７０】
これらの中で、前記Ｆｅ（有機酸アニオン）塩を形成する有機酸アニオンの基本化合物としては、有機スルホン酸または有機カルボン酸、有機リン酸、有機ホウ酸等が挙げられる。有機スルホン酸の具体例としては、ベンゼンスルホン酸やｐ−トルエンスルホン酸、メタンスルホン酸、エタンスルホン酸、α−スルホ−ナフタレン、β−スルホ−ナフタレン、ナフタレンジスルホン酸、アルキルナフタレンスルホン酸（アルキル基としてはブチル、トリイソプロピル、ジ−ｔ−ブチル等）等が使用される。
【００７１】
一方、有機カルボン酸の具体例としては、酢酸、プロピオン酸、安息香酸、シュウ酸等が挙げられる。さらに本発明においては、ポリアクリル酸、ポリメタクリル酸、ポリスチレンスルホン酸、ポリビニルスルホン酸、ポリビニル硫酸ポリ−α−メチルスルホン酸、ポリエチレンスルホン酸、ポリリン酸等の高分子電解質アニオンも使用される。なお、これら有機スルホン酸または有機カルボン酸の例は単なる例示であり、これらに限定されるものではない。また、前記アニオンの対カチオンは、Ｈ⁺、Ｎａ⁺、Ｋ⁺等のアルカリ金属イオン、または水素原子やテトラメチル基、テトラエチル基、テトラブチル基、テトラフェニル基等で置換されたアンモニウムイオン等が例示されるが、これらに限定されるものではない。前記の酸化剤のうち、特に好ましいのは、３価のＦｅ系化合物類、または塩化第一銅系、過硫酸アルカリ塩類、過硫酸アンモニウム塩類酸類、キノン類を含む酸化剤である。
【００７２】
導電性高分子の重合体組成物の製造方法において必要に応じて共存させるドーパント能を有するアニオン（酸化剤の還元体アニオン以外のアニオン）は、前述の酸化剤から産生される酸化剤アニオン（酸化剤の還元体）を対イオンに持つ電解質アニオンまたは他の電解質アニオンを使用することができる。具体的には例えば、ＰＦ₆ ^-、ＳｂＦ₆ ^-、ＡｓＦ₆ ^-の如き５Ｂ族元素のハロゲン化物アニオン、ＢＦ₄ ^-の如き３Ｂ族元素のハロゲン化物アニオン、Ｉ^-（Ｉ₃ ^-）、Ｂｒ^-、Ｃｌ^-の如きハロゲンアニオン、ＣｌＯ₄ ^-の如き過ハロゲン酸アニオン、ＡｌＣｌ₄ ^-、ＦｅＣｌ₄ ^-、ＳｎＣｌ₅ ^-等の如きルイス酸アニオン、あるいはＮＯ₃ ^-、ＳＯ₄ ^2-の如き無機酸アニオン、またはｐ−トルエンスルホン酸やナフタレンスルホン酸、炭素数１乃至５（Ｃ１〜５と略する）のアルキル置換ナフタレンスルホン酸等のスルホン酸アニオン、ＣＦ₃ＳＯ₃ ^-，ＣＨ₃ＳＯ₃ ^-の如き有機スルホン酸アニオン、またはＣＨ₃ＣＯＯ^-、Ｃ₆Ｈ₅ＣＯＯ^-のごときカルボン酸アニオン等のプロトン酸アニオンを挙げることができる。
【００７３】
また、同じく、ポリアクリル酸、ポリメタクリル酸、ポリスチレンスルホン酸、ポリビニルスルホン酸、ポリビニル硫酸、ポリ−α−メチルスルホン酸、ポリエチレンスルホン酸、ポリリン酸等の高分子電解質のアニオン等を挙げることができるが、これらに限定されるものではない。しかしながら、好ましくは、高分子系及び低分子系の有機スルホン酸化合物あるいはポリリン酸化合物のアニオンが挙げられ、望ましくは芳香族系のスルホン酸化合物（ドデシルベンゼンスルホン酸ナトリウム、ナフタレンスルホン酸ナトリウム等）がアニオン供出化合物として用いられる。
【００７４】
また、有機スルホン酸アニオンのうち、さらに有効なドーパントとしては、分子内に１つ以上のスルホアニオン基（−ＳＯ₃ ^-）とキノン構造を有するスルホキノン化合物や、アントラセンスルホン酸アニオンが挙げられる。
【００７５】
前記スルホキノン化合物のスルホキノンアニオンの基本骨格として、ｐ−ベンゾキノン、ｏ−ベンゾキノン、１，２−ナフトキノン、１，４−ナフトキノン、２，６−ナフトキノン、９，１０−アントラキノン、１，４−アントラキノン、１，２−アントラキノン、１，４−クリセンキノン、５，６−クリセンキノン、６，１２−クリセンキノン、アセナフトキノン、アセナフテンキノン、カンホルキノン、２，３−ボルナンジオン、９，１０−フェナントレンキノン、２，７−ピレンキノンが挙げられる。
【００７６】
対電極（対極）が固体の場合には、所望により用いられる外部引き出しリード（例えば、リードフレームなど）との電気的接触をよくするため、その上に導電体層を設けてもよい。
【００７７】
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ィルムなど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、ニッケルペーストなどが好ましいが、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、アルミメッキなどが挙げられる。また、蒸着金属としては、アルミニウム、ニッケル、銅、銀などが挙げられる。
【００７８】
具体的には、例えば第二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、ネオジム−一窒化二ニオブ結晶を含有する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、ニオブ合金、一窒化二ニオブ結晶を含有するニオブ、一窒化二ニオブ結晶を含有するニオブ合金、または、タンタルリードを有していてもよい。
【００７９】
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途のコンデンサ製品とすることができる。
【００８０】
また、対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、対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、ネオジム−一窒化二ニオブ結晶を含有するニオブ焼結体の電極側は、前記した、ニオブ、ニオブ合金、一窒化二ニオブ結晶を含有するニオブ、一窒化二ニオブ結晶を含有するニオブ合金、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。
【００８１】
以上、説明した本発明の実施態様にしたがって製造したニオブ合金を用いてコンデンサ用焼結体を作製し、該焼結体からコンデンサを製造することにより、漏れ電流値の小さく、高温特性及び耐熱特性の両方を満足した信頼性の良好なコンデンサを得ることができる。
【００８２】
また、本発明のコンデンサは、従来のタンタルコンデンサよりも容積の割に静電容量が大きく、より小型のコンデンサ製品を得ることができる。
これらの特性を持つ本発明のコンデンサは、例えば、アナログ回路及びデジタル回路中のバイパスコンデンサ、カップリングコンデンサとしての用途、電源回路で使用される大容量の平滑コンデンサとしての用途、及び従来のタンタルコンデンサの用途にも適用できる。
【００８３】
一般に、このようなコンデンサは電子回路中で多用されるので、本発明のコンデンサを用いれば、電子部品の配置や排熱の制約が緩和され、信頼性の高い電子回路を従来より狭い空間に収めることができる。さらに、本発明のコンデンサを用いれば、従来より小型で信頼性の高い電子機器、例えば、コンピュータ、ＰＣカード等のコンピュータ周辺機器、携帯電話などのモバイル機器、家電製品、車載機器、人口衛星、通信機器等を得ることができる。
【００８４】
【実施例】
以下、実施例及び比較例を挙げて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。
【００８５】
なお、各例における物性等の測定、評価方法は以下の通りである。
（１）一窒化二ニオブ結晶を含有するニオブ合金中の一窒化二ニオブ結晶の含有量
一窒化二ニオブ結晶及びニオブ合金に、質量既知の前記結晶を混合した後、Ｘ線回折測定した時の２θ回折強度と前記混合質量より作成した検量線より算出した。
（２）一窒化二ニオブ結晶を含有するニオブ合金中のニオブ以外の合金成分の含有量
原子吸光分析、ＩＣＰ発光分析またはＩＣＰ質量分析により求めた。
【００８６】
（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（プレシジョンＬＣＲメーターＨＰ４２８４Ａ型）を接続し、１２０Ｈｚでの容量をチップ加工したコンデンサの容量とした。
【００８７】
（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（直流、２０Ｖ）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。
【００８８】
（５）コンデンサの高温特性
１０５℃の雰囲気下、コンデンサを４Ｖ電圧印加した状態で2000時間放置した後、室温に戻したときの容量Ｃとの比：（Ｃ−Ｃ₀）／Ｃを高温特性と定義し、この比が±２０％以内に収まるものを良品と判定して、試料数と良品数の比で評価した。試料数は、各例とも５０個とした。
【００８９】
（６）コンデンサの耐熱性
コンデンサを厚さ1.5ｍｍの積層基板にハンダとともに搭載して、２３０℃のリフロー炉に３０秒かけて通過させ、これを３回繰り返した。通常、コンデンサは、リフロー炉通過時に約２３０℃×３０秒×３回加熱され、実用的な熱履歴（例えは、基板の表面に実装した部品のハンダ付け、基板の裏面に実装したハンダ付け、後付部品のハンダ付けを実施した場合の３回のハンダ付け熱履歴）に対しての評価がなされる。
【００９０】
リフロー炉を通過させる前と３回通過した後のＬＣ値を定格6.3Ｖで測定し、ＬＣ値が0.05ＣＶμＡ以下のものを良品と判定して、試料数と良品数の比で評価した。試料数は、各例とも５０個とした。
【００９１】
焼結体の作成法１：
ニオブインゴット１９８ｇとジルコニウムの粉末２ｇを用い、アーク溶解でジルコニウムを１原子％含むジルコニウム含有ニオブインゴット（合金）を作製した。このインゴット１５０ｇ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製のスパイクミルに、この水素化物を水で２０体積％のスラリーにしたもの及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1.33×１０²Ｐａ、５０℃の条件で減圧乾燥した。続いて、水素化ジルコニウム含有ニオブ粉を1.33×１０^-2Ｐａ、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１μｍであり、ジルコニウム含有量は１原子％（１質量％）であった。
【００９２】
このジルコニウム含有ニオブ粉１００ｇと、平均粒径が0.8μｍの一窒化二ニオブ結晶１００ｇをジルコニア製ボールとともにＳＵＳ３０４製のポットに入れ、更にイオン交換水２００ｇを加え、毎分４０回のスピードで回転させ、３時間混合した。このスラリーを1.33×１０²Ｐａ、５０℃の条件で減圧乾燥した。続いて、ニオブ製のバットに入れたジルコニウム含有ニオブ粉と一窒化二ニオブ結晶の混合粉を焼結炉に入れ、焼結体系内をアルゴン置換した後、６×１０^-3Ｐａの減圧下、1100℃で造粒した。その後、この造粒塊を解砕し、平均粒径１１０μｍの造粒粉を得た。この造粒粉のジルコニウム含有量は0.5質量％であり、一窒化二ニオブ結晶の含有量は５０質量％であった。
【００９３】
このようにして得られた、ジルコニウム−一窒化二ニオブ結晶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0.3ｃｍ×0.18ｃｍ×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の減圧下、1200℃で３０分放置することにより実施例の焼結体を得た。
【００９４】
焼結体の作成法２：
ニオブペレット9200ｇとジルコニウムペレット９２ｇをよく混合し、電子ビーム溶解法でジルコニウム１原子％含むジルコニウム含有ニオブインゴット（合金）を作製した。このインゴット5000ｇ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製のスパイクミルに、この水素化物を水で２０体積％のスラリーにしたもの及びジルコニアボールを入れ、１０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、５０℃の条件で減圧乾燥した。続いて、水素化ジルコニウム含有ニオブ粉を1.33×１０^-2Ｐａ、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0.9μｍであり、ジルコニウム含有量は１原子％（１質量％）であった。続いて、ニオブ製のバットに入れたジルコニウム含有ニオブ粉を焼結炉に入れ、焼結体系内をアルゴン置換した後、６×１０^-3Ｐａの減圧下、1100℃で造粒した。その後、この造粒塊を解砕し、平均粒径９０μｍの造粒粉を得た。この造粒粉のジルコニウム含有量は１質量％であった。
【００９５】
このジルコニウム含有ニオブ造粒粉をモリブデン製の反応容器に入れ、反応容器内を充分に窒素置換した後、窒素を流しながら５８０℃で５時間加熱し続け窒化した。室温まで冷却の後、反応容器内を充分にＡｒ置換した後、９５０℃で８時間加熱して、一窒化二ニオブ結晶に変化させた。室温まで冷却の後、ジルコニウム−一窒化二ニオブ結晶を含有するニオブ造粒粉を得た。
このジルコニウム−一窒化二ニオブ結晶を含有するニオブ造粒粉中のジルコニウム含有量は0.9質量％であり、一窒化二ニオブ結晶の含有量は５５質量％であった。
【００９６】
このようにして得られた、ジルコニウム−一窒化二ニオブ結晶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0.3ｃｍ×0.18ｃｍ×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の減圧下、1200℃で３０分放置することにより実施例の焼結体を得た。
【００９７】
焼結体の作成法３：
ニッケル製坩堝中、８０℃で充分に減圧乾燥したフッ化ニオブ酸カリウム2000ｇ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減圧乾燥した。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１０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、減圧乾燥した。作製したニオブ粉の平均粒径は0.9μｍであった。
【００９８】
このニオブ粉５００ｇをモリブデン製の反応容器に入れ、反応容器内を充分に窒素置換した後、窒素を流しながら５００℃で１０時間加熱し続け窒化した。室温まで冷却の後、反応容器内を充分にＡｒ置換し、８００℃で２０時間加熱して、一窒化二ニオブ結晶に変化させた。室温まで冷却の後、一窒化二ニオブ結晶を含有するニオブ粉を得た。
【００９９】
この一窒化二ニオブ結晶を含有するニオブ粉５００ｇと平均粒径が0.9μｍの水素化ジルコニウム１０ｇをジルコニア製ボールとともにＳＵＳ３０４製のポットに入れ、更にイオン交換水２００ｇを加え、毎分２０回のスピードで回転させ、５時間混合した。このスラリーを1.33×１０²Ｐａ、５０℃の条件で減圧乾燥した。続いて、ニオブ製のバットにこの水素化ジルコニウムと一窒化二ニオブ結晶を含有するニオブ粉の混合粉を入れた後、焼結炉にバットを入れ、焼結体系内をアルゴン置換した後、６×１０^-3Ｐａの減圧下、1150℃で造粒した。その後、この造粒塊を解砕し、平均粒径１５０μｍの造粒粉を得た。
このジルコニウム−一窒化二ニオブ結晶を含有するニオブ造粒粉中のジルコニウム含有量は１．８質量％であり、一窒化二ニオブ結晶の含有量は２５質量％であった。
【０１００】
このようにして得られた、ジルコニウム−一窒化二ニオブ結晶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0.3ｃｍ×0.18ｃｍ×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の減圧下、1200℃で３０分放置することにより実施例の焼結体を得た。
【０１０１】
焼結体の作成法４：
ニオブインゴット５００ｇ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製のスパイクミルに、この水素化物を水で２０体積％のスラリーにしたもの及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1.33×１０²Ｐａ、５０℃の条件で減圧乾燥した。
【０１０２】
続いて、水素化ニオブ粉を1.33×１０^-2Ｐａ、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１μｍであった。このニオブ粉を４×１０^-3Ｐａの減圧下、1100℃で造粒した。その後、造粒塊を解砕し、平均粒径１００μｍの造粒粉を得た。
【０１０３】
このようにして得られた、ニオブ造粒粉を0.3ｍｍφのニオブ線と共に成形し、およそ0.3ｃｍ×0.18ｃｍ×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の減圧下、1200℃で３０分放置することにより比較例の焼結体を得た。
【０１０４】
焼結体の作成法５：
ニッケル製坩堝中、８０℃で充分に減圧乾燥したフッ化ニオブ酸カリウム2000ｇ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減圧乾燥した。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１０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、減圧乾燥した。作製したニオブ粉の平均粒径は0.9μｍであった。このニオブ粉を４×１０^-3Ｐａの減圧下、1100℃で造粒した。その後、造粒塊を解砕し、平均粒径１００μｍの造粒粉を得た。
【０１０５】
このようにして得られた、ニオブ造粒粉を0.3ｍｍφのニオブ線と共に成形し、およそ0.3ｃｍ×0.18ｃｍ×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の減圧下、1200℃で３０分放置することにより比較例の焼結体を得た。
【０１０６】
コンデンサの作成法１：
焼結体の作成法２と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、６時間電解酸化して、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対電極層として二酸化マンガン層を形成した。引き続き、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。
【０１０７】
コンデンサの作成法２：
焼結体の作成法２と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、６時間電解酸化して、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対電極層として二酸化鉛と硫酸鉛の混合層を形成した。引き続き、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。
【０１０８】
コンデンサの作成法３：
焼結体の作成法２と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、６時間電解酸化して、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％水溶液とアント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対電極（対極）を形成した。
【０１０９】
引き続き、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。
【０１１０】
コンデンサの作成法４：
焼結体の作成法２と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、６時間電解酸化して、表面に誘電体酸化皮膜を形成した。次に、このニオブ燒結体を、過硫酸アンモニウム２５質量％を含む水溶液（溶液１）に浸漬した後引き上げ、８０℃で３０分乾燥させ、次いで誘電体を形成した燒結体を、３，４−エチレンジオキシチオフェン１８質量％を含むイソプロパノール溶液（溶液２）に浸漬した後引き上げ、６０℃の雰囲気に１０分放置することで酸化重合を行った。これを再び溶液１に浸漬し、さらに前記と同様に処理した。溶液１に浸漬してから酸化重合を行うまでの操作を８回繰り返した後、５０℃の温水で１０分洗浄を行い、１００℃で３０分乾燥を行うことにより、導電性のポリ（３，４−エチレンジオキシチオフェン）からなる対電極（対極）を形成した。
【０１１１】
引き続き、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。
【０１１２】
実施例１〜４０：
焼結体の作成法１または２と同様な方法で表２に示すように一窒化二ニオブ結晶の含有量、合金成分の含有量を変化させて焼結体を作成した。この焼結体５０個について、コンデンサの作成法１〜４の何れかの方法を用いてコンデンサを作成した。このコンデンサ（５０個）について、耐熱特性及び高温特性を評価した。その結果を表２に示す。
【０１１３】
実施例４１〜６０：
焼結体の作成法３と同様な方法で、一窒化二ニオブ結晶を含有するニオブ粉と表３に示した種類と量の添加物（合金成分となる元素またはその化合物）を用いて焼結体を作成した。この焼結体５０個について、コンデンサの作成法１〜４の何れかの方法を用いてコンデンサを作成した。このコンデンサ（５０個）について、耐熱特性及び高温特性を評価した。その結果を表３に示す。
【０１１４】
比較例１〜８：
実施例１〜６０と比較するために、一窒化二ニオブ結晶及び他方の合金成分を含まないニオブ焼結体を焼結体の作成方法４または５と同様な方法で作成した。この焼結体５０個についてコンデンサの作成法１〜４の何れかの方法を用いてコンデンサを作成した。このコンデンサ（５０個）について、耐熱特性及び高温特性を評価した。その結果を表２及び表３に示す。
【０１１５】
【表２】

【０１１６】
【表３】

【０１１７】
【発明の効果】
周期律表の２族乃至１６族からなる群から選ばれた少なくとも１種の元素を合金成分として含み、更に一窒化二ニオブ（Ｎｂ₂Ｎ）の結晶を含有したを作成し、その焼結体を用いてコンデンサを作成することにより、高温特性及び耐熱性の改善されたコンデンサが得られる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a capacitor, in particular, a niobium alloy for a capacitor, a niobium alloy sintered body capable of producing a capacitor having a large capacity per unit mass, and excellent in high temperature characteristics and heat resistance characteristics, and the sintered body. Concerning capacitors.
[0002]
[Prior art]
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 the anode body of the 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. As one of the studies for solving these drawbacks, a capacitor using a sintered body of a material powder having a dielectric constant larger than that of tantalum can be considered. Niobium and titanium are examples of materials having a large dielectric constant.
[0004]
JP-A-55-157226 (see Patent Document 1) discloses that niobium fine powder having a particle size of 2.0 μm or less is pressed from an agglomerated powder and sintered, and the molded sintered body is finely cut. And the manufacturing method of the sintered element for capacitors which joins a lead part to this and sinters again is indicated. However, the publication does not provide details on the capacitor characteristics.
[0005]
US Pat. No. 4,084,965 (see Patent Document 2) discloses a capacitor in which a niobium ingot is hydrogenated and pulverized to obtain a 5.1 μm niobium powder, which is sintered. However, the disclosed capacitor has a large leakage current (hereinafter sometimes abbreviated as “LC”) and is not practical.
[0006]
US Pat. No. 5,242,481 (see Patent Document 3) discloses a production method that uses a reducing agent such as metallic magnesium to reduce the oxygen content of niobium powder, tantalum powder, and an alloy of niobium and tantalum to 300 ppm or less. Has been. However, the publication does not describe a capacitor using these powders.
[0007]
In US Pat. No. 6,171,363 (see Patent Document 4), tantalum, niobium, titanium, molybdenum, tungsten, vanadium, zirconium, and hafnium oxide are reduced by using a reducing agent such as vaporized magnesium and calcium. Discloses a method for producing a metal of tantalum, niobium, titanium, molybdenum, tungsten, vanadium, zirconium, hafnium or an alloy thereof. Niobium-tantalum alloys, niobium-titanium alloys, and tantalum-titanium alloys are described as capacitor materials instead of tantalum. However, the examples are only tantalum or niobium, there is no illustration of niobium alloy, and there is no description of the performance of the capacitor.
[0008]
In WO 00/67936 pamphlet (see Patent Document 5), reduction is performed using a reducing agent such as magnesium or calcium vaporized from tantalum, niobium, titanium, molybdenum, tungsten, vanadium, zirconium, or hafnium oxide. Thus, a method for producing a metal of tantalum, niobium, titanium, molybdenum, tungsten, vanadium, zirconium, hafnium or an alloy thereof is disclosed. In this, an example of a niobium-tantalum alloy is described. It has been shown that a niobium-tantalum alloy containing 15 atomic% tantalum has a larger capacity as the thickness of the dielectric film per unit voltage becomes thinner than that of niobium alone. However, the examples are only tantalum or niobium, there is no illustration of niobium alloy, and there is no description of the performance of the capacitor.
[0009]
Japanese Patent Laid-Open No. 10-242004 (see Patent Document 6) 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.
[0010]
Japanese Laid-Open Patent Publication No. 11-329902 (see Patent Document 7) discloses a niobium solid capacitor with little change in capacitance before and after the reflow process during component mounting. However, the capacity of the disclosed capacitor is as small as 2 μF, and there is no disclosure regarding the high-temperature characteristics described later with respect to the capacity, and the heat resistance and the appearance frequency of defective / non-defective products regarding LC.
[0011]
None of these conventional niobium capacitors sufficiently satisfy all of the capacity, high temperature characteristics, and heat resistance characteristics, and are not put into practical use or are limited to extremely limited uses even when put into practical use.
[0012]
Initial capacity C at room temperature₀And the capacitance C when the capacitor is allowed to stand for 2000 hours in a 105 ° C. atmosphere and then returned to room temperature, (C−C₀) / C0 is defined as a high temperature characteristic. When a capacitor is manufactured by combining a counter electrode after electrolytically oxidizing the sintered body, the high temperature characteristic is usually within ± 20% for a tantalum capacitor using a tantalum sintered body. In contrast, the conventional niobium capacitor using the niobium sintered body sometimes appears within ± 20%.
[0013]
Leakage current value (LC value) measured after connecting 50 prepared capacitors to a prepared substrate in a reflow oven is 0.05 CV value (product of capacity and rated voltage) or less. When the substrate is put into the reflow furnace, the temperature at the external terminal of the capacitor is maintained at 230 ° C. for 30 seconds per charge of the reflow furnace, and the number of times of loading the substrate is three times. When the capacitor is manufactured by combining the counter electrode after electrolytic oxidation of the sintered body, the number of capacitors having a value of 0.05 CV or more is usually 0/50 in the heat resistance characteristics of the sintered body using the tantalum powder. On the other hand, in the sintered body using the conventional niobium powder, there was a case where a product having a value of 0.05 CV or more appeared.
[0014]
The niobium sintered body is inferior in stability of the dielectric oxide film as compared with the tantalum sintered body. The difference is significant at high temperatures. There are many possible reasons for this, but as one of them, the composition of the dielectric oxide film and the composition of the niobium sintered body electrode are different, so the deterioration of the dielectric oxide film is accelerated by thermal strain at high temperature. Is assumed.
[0015]
In this way, capacitors using niobium sintered bodies have to be estimated with low reliability at room temperature, and as a result, they may be judged to have poor service life, and are only practically used in a limited way. It was.
[0016]
[Patent Document 1]
JP-A-55-157226
[Patent Document 2]
U.S. Pat.No. 4,084,965
[Patent Document 3]
U.S. Pat.No. 5,242,481
[Patent Document 4]
U.S. Patent No. 6,171,363
[Patent Document 5]
International Publication No. 00/67936 Pamphlet
[Patent Document 6]
Japanese Patent Laid-Open No. 10-242004
[Patent Document 7]
Japanese Patent Laid-Open No. 11-329902
[0017]
[Means for Solving the Invention]
Accordingly, an object of the present invention is to provide a niobium capacitor having a high capacity, a small leakage current value and good high-temperature characteristics and heat resistance characteristics, and a sintered body, niobium alloy and niobium composition that provide the same.
[0018]
[Means for Solving the Problems]
As a result of intensive investigations in view of the above problems, the inventors of the present invention contain at least one element selected from the group consisting of groups 2 to 16 of the periodic table as an alloy component, and further contain niobium mononitride crystals. It has been found that the above-mentioned problems can be solved by using a niobium alloy and a niobium alloy sintered body.
[0019]
In order to improve the deterioration of the dielectric oxide film due to the thermal strain at a high temperature described above, niobium contains at least one element selected from the group consisting of groups 2 to 16 of the periodic table as an alloy component. Although alloying can be relaxed to some extent due to heat, it is still not sufficient. By adding a niobium mononitride crystal to a niobium alloy containing at least one element selected from the group consisting of groups 2 to 16 of the periodic table as an alloy component, for example, a high temperature as previously assumed As a result, it is estimated that both the high temperature characteristics and the heat resistance characteristics of capacitors using these niobium alloys and niobium alloy sintered bodies are greatly improved.
[0020]
These niobium alloy sintered bodies are used as one electrode, and the above problem is solved by manufacturing a capacitor composed of a counter electrode and a dielectric interposed between the two electrodes. Capacitors with good heat resistance can be manufactured.
[0021]
That is, the present invention relates to the following niobium alloy, niobium composition powder, a sintered body using the same, a capacitor using the same, and a method for manufacturing the same.
1. A niobium alloy containing at least one element selected from the group consisting of groups 2 to 16 of the periodic table as an alloy component and containing a niobium mononitride crystal.
2. 2. The niobium alloy for capacitors as described in 1 above, wherein the alloy component is at least one element selected from the group consisting of groups 3 to 16 of the periodic table.
3. 2. The niobium alloy for capacitors as described in 1 above, wherein the alloy component is contained in an amount of 0.01 to 10 atomic%.
4). 4. The niobium alloy for capacitors as described in any one of 1 to 3 above, wherein the niobium mononitride crystal is contained in an amount of 0.1 to 70% by mass.
[0022]
5). 5. The niobium alloy for capacitors as described in any one of 1 to 4 above, wherein the niobium alloy is a powder having an average particle size of 0.05 to 5 μm.
6). Niobium alloy 0.5-40m²6. The niobium alloy for capacitors as described in any one of 1 to 5 above, having a BET specific surface area of / g.
7. 7. The niobium alloy according to any one of items 1 to 6, wherein the niobium alloy further includes at least one element selected from the group consisting of boron, nitrogen, carbon, and sulfur in addition to the alloy component and the niobium mononitride crystal. Niobium alloy for capacitors.
8). Niobium composition powder for a capacitor comprising an element or compound thereof, niobium or niobium compound, and niobium mononitride crystal as an alloy component of at least one niobium alloy selected from the group consisting of groups 2 to 16 of the periodic table .
[0023]
9. 9. The niobium composition powder for a capacitor as described in 8 above, wherein the alloy component is at least one element selected from the group consisting of groups 3 to 16 of the periodic table.
10. 8. A niobium granule for a capacitor obtained by granulating the niobium alloy powder according to any one of 1 to 7 above.
11. 10. A niobium granule for a capacitor obtained by granulating the niobium composition powder according to 8 or 9 above.
12 12. The niobium granule for capacitor as described in 10 or 11 above, wherein the niobium granule has an average particle size of 10 to 500 μm.
[0024]
13. 8. A sintered body obtained by sintering the niobium alloy according to any one of items 1 to 7.
14 10. A sintered body obtained by sintering the niobium composition powder according to item 8 or 9.
15. 13. A sintered body obtained by sintering the niobium granule according to any one of items 10 to 12.
16. The sintered body according to any one of the preceding items 13 to 15 is used as one electrode, and is composed of a dielectric formed on the surface of the sintered body and a counter electrode provided on the dielectric. Capacitor.
[0025]
17. A powder containing niobium is sintered to obtain a sintered body of a niobium alloy. This sintered body is used as one electrode, a dielectric is formed on the surface of the sintered body, and a counter electrode is formed on the dielectric. A method for producing a capacitor, comprising: a step of incorporating a niobium mononitride crystal into a sintered body.
18. 18. The method for producing a capacitor as described in 17 above, wherein the step of incorporating the niobium mononitride crystal into the sintered body is performed by mixing the niobium-containing powder with the niobium mononitride crystal and / or a hydride thereof.
19. 18. The method for producing a capacitor as described in 17 above, wherein the step of incorporating the niobium mononitride crystal into the sintered body is performed by nitriding a powder containing niobium and generating the niobium mononitride crystal from the nitrided niobium.
20. 18. The method for producing a capacitor as described in 17 above, wherein the step of adding the niobium mononitride crystal to the sintered body is performed by nitriding the niobium alloy sintered body and generating the niobium mononitride crystal from the nitrided niobium. .
[0026]
21. The formation of niobium mononitride crystal is 10²-10⁶21. The method for producing a capacitor as described in 19 or 20 above, which is performed by exposing to Pa, 800 ° C. to 1500 ° C. for 1 minute to 100 hours.
22. 20. The method for manufacturing a capacitor as described in any one of 17 to 19 above, wherein the powder containing niobium is a niobium alloy and / or a hydride thereof.
23. The preceding items 17 to 19 wherein the niobium-containing powder contains niobium and / or a hydride thereof and an element that is an alloy component of at least one niobium alloy selected from the group consisting of groups 2 to 16 of the periodic table. The capacitor | condenser manufacturing method of any one of these.
[0027]
24. 24. The method for producing a capacitor as described in 23 above, wherein the alloy component is at least one element selected from the group consisting of groups 3 to 16 of the periodic table.
25. An electronic circuit using the capacitor as described in 16 above.
26. Electronic equipment using the capacitor according to item 16 above.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment for obtaining a niobium alloy, a niobium composition powder, a sintered body using the niobium alloy, and a capacitor using the niobium alloy according to the present invention will be described.
[0029]
In the present invention, at least one element selected from the group consisting of Groups 2 to 16, preferably Groups 3 to 16 of the periodic table is used as a raw material that can satisfy both high temperature characteristics and heat resistance characteristics. A niobium alloy further containing a niobium mononitride crystal can be used as the niobium alloy contained as an alloy component. In addition, the alloy used by this invention contains the solid solution with the said alloy component. The content of the niobium mononitride crystal is preferably 0.1 to 70% by mass. Further, the niobium alloy may be further treated with at least one element selected from the group consisting of boron, nitrogen, carbon and sulfur elements.
[0030]
The total content of at least one element selected from the group consisting of groups 2 to 16 of the periodic table contained in the niobium alloy of the present invention as an alloy component (excluding niobium) is 10 atomic% in the niobium alloy. Hereinafter, it is preferably 0.01 to 10 atomic%, more preferably 0.01 to 7 atomic%. When the total content of the elements is lower than 0.01 atomic%, even when the niobium mononitride crystal is contained, the strain of the electrolytic oxide film (dielectric film) formed in the later-described electrolytic oxidation is suppressed against heat at high temperature. It is difficult to obtain an effect, and as a result, both high temperature characteristics and heat resistance characteristics cannot be satisfied. On the other hand, when the total content of the elements exceeds 10 atomic%, the content of niobium itself in the niobium alloy decreases, and as a result, the capacity as a capacitor decreases. Therefore, the total content of the alloy component elements of the niobium alloy containing at least one element selected from the group consisting of groups 2 to 16 of the periodic table as the alloy component is 0.01 to 10 atomic%. preferable. In order to further reduce the leakage current value, the element content in the niobium alloy is preferably 7 atomic% or less, more preferably 0.1 to 7 atomic%.
[0031]
The average particle diameter of the niobium alloy powder in which niobium mononitride crystal is contained in a niobium alloy containing at least one element selected from the group consisting of groups 2 to 16 of the periodic table of the present invention as an alloy component is: In order to realize a high capacity by increasing the specific surface area of the powder, it is 5 μm or less, preferably 0.05 to 4 μm.
[0032]
The average particle size (D of the niobium alloy powder (produced by the pulverization method) containing zirconium and niobium mononitride crystals prepared by the inventors as an example.₅₀; Μm) and specific surface area (S; m)²/ G) is shown in Table 1.
[0033]
[Table 1]

[0034]
The average particle size shown in Table 1 (D₅₀; Μm) is a value measured using a particle size distribution analyzer (trade name “Microtrac” manufactured by Microtrac) (D₅₀The value represents a particle size value corresponding to a cumulative mass% of 50 mass%. The specific surface area is a value measured by the BET method.
[0035]
If the average particle size of the niobium alloy powder exceeds 5 μm, a large capacitor capacity cannot be achieved. On the other hand, when the average particle size is less than 0.05 μm, when a sintered body is produced from the powder, the pore size is small and the number of closed pores is increased, and impregnation with a cathode agent described later tends to be difficult. Therefore, as a result, it is difficult to increase the capacitor capacity, and it is not very suitable as a niobium alloy sintered body for capacitors.
[0036]
From the above points, in the present invention, it is possible to achieve a large capacitor capacity by using niobium alloy powder having an average particle diameter of 0.05 to 5 μm.
[0037]
The niobium alloy of the present invention is at least 0.5 m²A powder having a BET specific surface area of / g is preferred, more preferably at least 1 m²A powder having a BET specific surface area of / g is preferred, and also at least 2 m²A powder having a BET specific surface area of / g is preferred. The niobium powder of the present invention is 0.5 to 40 m.²A powder having a BET specific surface area of 1 / g is preferable, and further 1 to 20 m²A powder having a BET specific surface area of / g is particularly preferred.
As described above, the niobium alloy powder containing zirconium-niobium mononitride crystal used for preparing a sintered body has an average particle diameter of 0.5 to 4 μm is particularly preferable.
[0038]
Hereinafter, the present invention will be described mainly using a niobium alloy containing zirconium-niobium mononitride crystal or a niobium alloy containing neodymium-niobium mononitride crystal as an example, but the present invention is not limited thereto. The following contents also apply to a niobium alloy containing at least one element selected from the group consisting of groups 2 to 16 of the periodic table as an alloy component and also a niobium alloy containing a niobium mononitride crystal. Applied.
[0039]
A niobium alloy powder containing zirconium-niobium mononitride crystal having an average particle diameter as described above is a niobium hydrogenated alloy containing zirconium obtained by pulverization of a hydride such as a zirconium-niobium alloy ingot, pellet, or powder. Or by mixing a niobium alloy powder containing zirconium dehydrogenated from this hydrogenated alloy with a niobium mononitride crystal and / or a hydride of niobium mononitride crystal having an average particle size of 0.05 μm to 5 μm. can get. This mixing may be performed by mixing powders in an inert gas (Ar, He, nitrogen, etc.) atmosphere at a temperature below room temperature, or by using a suitable solvent such as water, methanol, dichloroethane, or toluene. You may do it. When an appropriate solvent is used, it is desirable to distill off the solvent at a temperature of 50 ° C. or lower under reduced pressure. A sintered body may be prepared using the obtained mixed powder, and this mixed powder may be used in a reducing atmosphere (for example, Ar, He, H₂Etc.) 10^-3-10⁶Even if it makes a sintered compact using this mixed powder created by using a process such as crushing if necessary, it is exposed to a temperature of 200 ° C. to 1500 ° C. at a pressure of Pa (Pascal) for 1 minute to 100 hours. good.
[0040]
Further, as another method for producing a niobium alloy containing zirconium-niobium mononitride crystal, for example, an average particle size obtained by pulverization of a hydride such as a zirconium-niobium alloy ingot, a pellet, and a powder is 0.5 to Niobium hydride alloy powder containing 5 μm of zirconium or niobium alloy powder containing zirconium obtained by dehydrogenating this hydrogenated alloy under nitrogen atmosphere²-10⁶After nitrogenating by exposure to a temperature of 200 ° C. to 750 ° C., preferably a temperature of 300 ° C. to 600 ° C. for 1 minute to 100 hours at a pressure of Pa, and under an inert gas atmosphere such as Ar and He, 10²-10⁶Zirconium mononitride is obtained by changing niobium nitride to niobium mononitride crystal by exposing it to a temperature of 800 ° C. to 1500 ° C., preferably at a temperature of 850 ° C. to 1100 ° C. for 1 minute to 100 hours at a pressure of Pa. A niobium alloy containing a niobium crystal may be manufactured. This method may be applied to a sintered body after sintering instead of the niobium alloy.
[0041]
Further, as another production method, niobium ingot, a method by pulverization of pellet hydride, a method of dehydrogenating this niobium hydride powder, a method by pulverization of sodium fluoride of potassium fluoride niobate, or oxidation Using niobium powder or niobium hydride powder produced by a method such as pulverization of a reduced product reduced using at least one of niobium hydrogen, carbon, magnesium, aluminum, cerium, lanthanum, misch metal, etc., nitrogen 10 atmospheres²-10⁶After nitrogenating by exposure to a temperature of 200 ° C. to 750 ° C., preferably a temperature of 300 ° C. to 600 ° C. for 1 minute to 100 hours at a pressure of Pa, and under an inert gas atmosphere such as Ar and He, 10²-10⁶Niobium nitride is converted into niobium mononitride crystals by exposing to a temperature of 800 ° C. to 1500 ° C., preferably 850 ° C. to 1100 ° C. for 1 minute to 100 hours at a pressure of Pa, and if necessary, disintegrated. After obtaining niobium powder containing niobium mononitride crystals using a process such as neodymium powder, neodymium hydride, oxide, sulfide, boride, carbide, sulfate, halide salt, nitrate , Organic acid salts, complex salts and the like may be mixed.
[0042]
The niobium alloy containing the neodymium-niobium mononitride crystal thus obtained is mixed with neodymium-containing niobium powder and / or niobium powder having an average particle size of 0.05 μm to 5 μm, and the content of the niobium mononitride crystal And / or the content of neodymium may be adjusted, and one niobium alloy powder containing neodymium-niobium mononitride crystals mixed with a niobium mononitride crystal having an average particle diameter of 0.05 μm to 5 μm. The content of the niobium nitride crystal may be adjusted.
[0043]
The niobium alloy powder containing the neodymium-niobium mononitride crystal for capacitors of the present invention may be used after granulating the niobium alloy powder containing the neodymium-niobium mononitride crystal into an appropriate shape. Then, after granulation, an appropriate amount of ungranulated niobium powder may be mixed and used.
[0044]
[Granulated product]
Examples of the granulation method include, for example, a method in which niobium alloy powder containing ungranulated neodymium-niobium mononitride crystal is left under high vacuum and heated to an appropriate temperature and then crushed, camphor, polyacrylic acid, Mixing a suitable binder such as polymethyl acrylate and polyvinyl alcohol with a solvent such as acetone, alcohols, acetates and water and a niobium alloy containing ungranulated or granulated neodymium-niobium mononitride crystals After crushing, suitable binders such as camphor, polyacrylic acid, polymethyl acrylate, polyvinyl alcohol and solvents such as acetone, alcohols, acetates, water and ungranulated or granulated neodymium -After mixing niobium alloy powder containing niobium mononitride crystals, sintering under high vacuum, and adding added binder and solvent. A method of pulverizing a niobium alloy block containing neodymium-niobium mononitride crystals that have been removed by gasification, sublimation or pyrolysis, and barium oxide, magnesium oxide, etc. and acetone, alcohols, acetic acid After mixing a solvent such as esters and water and a non-granulated or granulated niobium alloy powder containing neodymium-niobium mononitride crystals, sintering under high vacuum, pulverization, nitric acid, hydrochloric acid, etc. Examples thereof include a method of removing barium oxide, magnesium oxide and the like by dissolving them in an acid solution or a solution containing a chelating agent.
[0045]
The niobium alloy containing the neodymium-niobium mononitride crystal thus granulated improves the pressure moldability when producing a sintered body. In this case, the average particle size of the granulated powder is preferably 10 to 500 μm. When the average particle size of the granulated powder is 10 μm or less, partial blocking occurs, and the fluidity to the mold becomes poor. If it is 500 μm or more, the molded body after pressure molding tends to be chipped. Furthermore, after sintering the pressure-molded body, the average particle diameter of the granulated powder is particularly preferably 30 μm to 250 μm because it is easy to impregnate the cathode agent when manufacturing the capacitor. The niobium alloy powder containing neodymium-niobium mononitride crystals thus granulated is extremely easy to flow with an angle of repose of 60 degrees or less. Moreover, the surface is partially oxidized, and the oxygen content is 3000 ppm to 100000 ppm, and the amount of Fe, Cr, Ni, Ba, Mg, Si, Al, carbon, etc. as impurities mixed from the equipment and raw materials used. Was several hundred ppm or less.
[0046]
The sintered niobium alloy containing the neodymium-niobium mononitride crystal for capacitors of the present invention contains the above-mentioned neodymium-niobium mononitride crystal-containing niobium alloy powder or granulated neodymium-niobium mononitride crystal. Sintered niobium alloy granulated powder is produced. The method for producing the sintered body is not particularly limited. For example, after the niobium alloy powder containing neodymium-niobium mononitride crystal is pressed into a predetermined shape,^-Five-10²It is obtained by heating at Pa for several minutes to several tens of hours, 500 ° C. to 2000 ° C., preferably 900 ° C. to 1500 ° C., more preferably 900 ° C. to 1300 ° C.
[0047]
In order to further improve the leakage current value of the niobium alloy powder, granulated powder, and sintered body containing neodymium-niobium mononitride crystal thus obtained, niobium containing neodymium-niobium mononitride crystal Part of the alloy powder, granulated powder, and sintered body may be nitrided, borated, carbonized, sulfided, or a plurality of these treatments. Niobium alloy nitride containing neodymium-niobium mononitride crystal, boride of niobium alloy containing neodymium-niobium mononitride crystal, carbide of niobium alloy containing neodymium-niobium mononitride crystal, The sulfide of the niobium alloy containing neodymium-niobium mononitride crystal may contain any of them, or a combination of two or more of these.
[0048]
The combined amount, that is, the total content of nitrogen, boron, carbon, and sulfur varies depending on the shape of the niobium alloy containing the neodymium-niobium mononitride crystal, but more than 0 ppm and less than or equal to 200,000 ppm, preferably 50 ppm to 100000 ppm, more preferably 200 ppm to 20000 ppm. If it exceeds 200,000 ppm, the capacitance characteristics deteriorate and it is not suitable as a capacitor.
[0049]
The niobium alloy powder, granulated powder, and sintered body containing neodymium-niobium mononitride crystal are nitrided by liquid nitriding, ion nitriding, gas nitriding, or a combination thereof. be able to. Gas nitriding in a nitrogen gas atmosphere is preferable because the apparatus is simple and easy to operate. For example, the gas nitriding method in a nitrogen gas atmosphere is achieved by leaving the niobium alloy powder, granulated powder, and sintered body containing the neodymium-niobium mononitride crystal in a nitrogen atmosphere. The temperature of the nitriding atmosphere is 2000 ° C. or less, the standing time is within 100 hours, and niobium alloy powder, granulated powder, and sintered body containing neodymium-niobium mononitride crystals of the target nitriding amount are obtained. Further, the processing time can be shortened by processing at a higher temperature.
[0050]
Niobium alloy powder, neodymium mononitride crystal containing niobium mononitride, granulated powder, and sintered body may be borated by gas boriding or solid phase boriding. For example, a niobium alloy powder, granulated powder, and sintered body containing neodymium-niobium mononitride crystal together with a boron halide boron source such as boron pellets and trifluoroboron under reduced pressure at 2000 ° C. or less for 1 minute to It can be left for about 100 hours.
[0051]
Carbonization of the niobium alloy powder, granulated powder, and sintered body containing neodymium-niobium mononitride crystal may be any of gas carbonization, solid phase carbonization, and liquid carbonization. For example, a niobium alloy powder containing a neodymium diniobium mononitride crystal, a granulated powder, and a sintered body together with a carbon source such as a carbon material or an organic substance having carbon such as methane, and under reduced pressure at 2000 ° C. or less for 1 minute to It can be left for about 100 hours.
[0052]
The sulfide method for the niobium alloy powder, granulated powder, and sintered body containing neodymium-niobium mononitride crystal may be any of gas sulfide, ion sulfide, and solid phase sulfide. For example, the gas sulfiding method in a sulfur gas atmosphere can be achieved by leaving the niobium alloy powder, granulated powder, and sintered body containing the neodymium-niobium mononitride crystal in a sulfur atmosphere. The temperature of the sulfiding atmosphere is 2000 ° C. or less and the standing time is 100 hours or less, so that niobium powder, granulated powder, and sintered body having a desired sulfiding amount can be obtained. Further, the processing time can be shortened by processing at a higher temperature.
[0053]
Next, manufacturing of the capacitor element will be described.
For example, a lead wire made of a valve metal such as niobium or tantalum and having an appropriate shape and length is prepared, and a part of the lead wire is inserted into the molded body when the niobium powder is pressure-molded as described above. The lead wire is assembled and designed so as to be a lead for the sintered body.
[0054]
A capacitor can be manufactured from the above-described sintered body as one electrode and a dielectric interposed between the counter electrodes. Here, a dielectric mainly composed of niobium oxide is preferably used as the dielectric of the capacitor. The dielectric mainly composed of niobium oxide can be obtained, for example, by forming a niobium alloy sintered body containing neodymium-niobium mononitride crystal as one electrode in an electrolytic solution. In order to form a niobium alloy electrode containing neodymium-niobium mononitride crystal in an electrolytic solution, usually a protonic acid aqueous solution, for example, 0.1% phosphoric acid aqueous solution, sulfuric acid aqueous solution or 1% acetic acid aqueous solution, adipic acid aqueous solution Is done using. When a niobium alloy electrode containing a neodymium-niobium mononitride crystal is formed in an electrolytic solution to obtain a niobium oxide dielectric, the capacitor of the present invention becomes an electrolytic capacitor and a niobium alloy containing neodymium-niobium mononitride crystal The electrode becomes the anode.
[0055]
In the capacitor of the present invention, the counter electrode of the niobium sintered body 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 is used. ) Can be used. 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. Specific examples of the organic semiconductor include an organic semiconductor composed of benzopyrroline tetramer and chloranil, an organic semiconductor composed mainly of tetrathiotetracene, an organic semiconductor composed mainly of tetracyanoquinodimethane, or the following general formula (1 ) Or a conductive polymer containing a repeating unit represented by the general formula (2).
[0056]
[Chemical 1]

[0057]
Where R¹~ R^FourEach independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, a saturated or unsaturated alkyl group, an alkoxy group or an alkyl ester group, or a halogen atom, nitro group, cyano group, primary, 2 Quaternary or tertiary amino group, CF_ThreeRepresents a monovalent group selected from the group consisting of a group, a phenyl group and a substituted phenyl group. R¹And R²And R^ThreeAnd R^FourThe hydrocarbon chains of the divalent group are bonded to each other at any position to form at least one or more 3- to 7-membered saturated or unsaturated hydrocarbon cyclic structures together with carbon atoms substituted by such groups. A chain may be formed. The cyclic bond chain may contain a bond of carbonyl, ether, ester, amide, sulfide, sulfinyl, sulfonyl, or imino at any position. X represents an oxygen, sulfur or nitrogen atom, R^FiveIs present only when X is a nitrogen atom and independently represents hydrogen or a linear or branched saturated or unsaturated alkyl group having 1 to 10 carbon atoms.
[0058]
Furthermore, in the present invention, R in the general formula (1) or the general formula (2)¹~ R^FourAre preferably each independently a hydrogen atom, a straight or branched saturated or unsaturated alkyl group or alkoxy group having 1 to 6 carbon atoms, and R¹And R²And R^ThreeAnd R^FourMay be bonded to each other to form a ring.
[0059]
Furthermore, in the present invention, the conductive polymer containing a 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.
[0060]
[Chemical formula 2]

[0061]
Where R⁶And R⁷Each independently contains a hydrogen atom, a linear or branched saturated or unsaturated alkyl group having 1 to 6 carbon atoms, or two alkyl elements in which the alkyl groups are bonded to each other at an arbitrary position. It represents a substituent that forms a cyclic structure of at least one or more 5- to 7-membered saturated hydrocarbon. The cyclic structure includes those having a vinylene bond which may be substituted and those having a phenylene structure which may be substituted.
[0062]
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.
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 may be used alone or in combination of two or more.
[0063]
Examples of the polymer containing a repeating unit represented by the general formula (1) or (2) include polyaniline, polyoxyphenylene, polyphenylene sulfide, polythiophene, polyfuran, polypyrrole, polymethylpyrrole, and substituted derivatives thereof. And copolymers. Of these, polypyrrole, polythiophene, and substituted derivatives thereof (for example, poly (3,4-ethylenedioxythiophene)) are preferable.
[0064]
Conductivity of 10 as the organic semiconductor and inorganic semiconductor.^-2-10^ThreeWhen a capacitor in the S / cm range is used, the impedance value of the manufactured capacitor becomes smaller and the capacitance at high frequency can be further increased.
[0065]
As the method for producing the conductive polymer layer, for example, aniline, thiophene, furan, pyrrole, methylpyrrole or a polymerizable compound of these substituted derivatives may be oxidized enough to cause an oxidation reaction of dehydrogenative two-electron oxidation. A method of polymerizing by the action of the agent is employed. The polymerization reaction from the polymerizable compound (monomer) includes, for example, vapor phase polymerization of a monomer, solution polymerization, and the like, and is formed on the surface of a niobium sintered body having a dielectric. In the case where the conductive polymer is an organic solvent-soluble polymer that can be applied by solution, a method in which the conductive polymer is formed by applying to the surface is employed.
[0066]
As one of preferred production methods by solution polymerization, a niobium sintered body having a dielectric layer formed is immersed in a solution containing an oxidizing agent (solution 1), and then immersed in a solution containing a monomer and a dopant (solution 2). And a method of polymerizing and forming a conductive polymer layer on the surface. Further, the sintered body may be immersed in the solution 1 after being immersed in the solution 2. Moreover, in the said solution 2, you may use for the said method as a monomer solution which does not contain a dopant. Moreover, when using a dopant, you may use it making it coexist in the solution containing an oxidizing agent.
[0067]
A dense and layered conductive polymer layer can be easily formed by repeating such a polymerization process operation once or more, preferably 3 to 20 times, with respect to the niobium sintered body having a dielectric. .
[0068]
In the method for manufacturing a capacitor of the present invention, the oxidizing agent may be any oxidizing agent that does not adversely affect the capacitor performance, and can be used to improve the electric power of the conductive polymer by using the reduced form of the oxidizing agent as a dopant. Industrially inexpensive compounds that are easy to handle in production are preferred.
[0069]
As such an oxidizing agent, specifically, for example, FeCl_ThreeAnd FeClO_Four, Fe (III) compounds such as Fe (organic acid anion) salts, or anhydrous aluminum chloride / cuprous chloride, alkali metal persulfates, ammonium persulfates, peroxides, manganese such as potassium permanganate Quinones such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetrachloro-1,4-benzoquinone, tetracyano-1,4-benzoquinone, iodine, bromine, etc. Examples include halogens, peracids, sulfuric acid, fuming sulfuric acid, sulfur trioxide, sulfonic acids such as chlorosulfuric acid, fluorosulfuric acid, and amidosulfuric acid, ozone, and the like, and combinations of these oxidizing agents.
[0070]
Among these, examples of the basic compound of the organic acid anion that forms the Fe (organic acid anion) salt include organic sulfonic acid or organic carboxylic acid, organic phosphoric acid, and organic boric acid. Specific examples of the organic sulfonic acid include benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid, ethanesulfonic acid, α-sulfo-naphthalene, β-sulfo-naphthalene, naphthalene disulfonic acid, alkylnaphthalenesulfonic acid (alkyl group). As butyl, triisopropyl, di-t-butyl, etc.).
[0071]
On the other hand, specific examples of the organic carboxylic acid include acetic acid, propionic acid, benzoic acid, oxalic acid and the like. Furthermore, in the present invention, polyelectrolyte anions such as polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyvinyl sulfonic acid, polyvinyl sulfate poly-α-methyl sulfonic acid, polyethylene sulfonic acid, and polyphosphoric acid are also used. In addition, the example of these organic sulfonic acid or organic carboxylic acid is a mere illustration, and is not limited to these. The counter cation of the anion is H⁺, Na⁺, K⁺Examples thereof include, but are not limited to, alkali metal ions such as hydrogen ions, ammonium ions substituted with hydrogen atoms, tetramethyl groups, tetraethyl groups, tetrabutyl groups, tetraphenyl groups, and the like. Of the above oxidizing agents, particularly preferred are oxidizing agents containing trivalent Fe compounds, or cuprous chloride, alkali persulfates, ammonium persulfates, and quinones.
[0072]
An anion (anion other than the reductant anion of the oxidant) having a dopant ability to coexist as necessary in the method for producing a polymer composition of a conductive polymer is an oxidant anion (oxidation) produced from the oxidant described above. It is possible to use an electrolyte anion having a reductant of the agent) as a counter ion or another electrolyte anion. Specifically, for example, PF₆ ^-, SbF₆ ^-, AsF₆ ^-5B group element halide anions such as BF_Four ^-A halide anion of a group 3B element such as I^-(I_Three ^-), Br^-, Cl^-A halogen anion such as_Four ^-Perhalogenate anions such as AlCl_Four ^-, FeCl_Four ^-, SnCl_Five ^-Lewis acid anions such as NO or NO_Three ^-, SO_Four ^2-Inorganic acid anions such as p-toluenesulfonic acid, naphthalenesulfonic acid, sulfonic acid anions such as alkyl-substituted naphthalenesulfonic acid having 1 to 5 carbon atoms (abbreviated as C1-5), CF_ThreeSO_Three ^-, CH_ThreeSO_Three ^-An organic sulfonate anion such as_ThreeCOO^-, C₆H_FiveCOO^-And protonic acid anions such as carboxylic acid anions.
[0073]
Similarly, anions of polymer electrolytes such as polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyvinyl sulfonic acid, polyvinyl sulfuric acid, poly-α-methyl sulfonic acid, polyethylene sulfonic acid, and polyphosphoric acid can be exemplified. However, it is not limited to these. However, preferably, anions of high molecular weight and low molecular weight organic sulfonic acid compounds or polyphosphoric acid compounds are used, and desirably aromatic sulfonic acid compounds (sodium dodecylbenzene sulfonate, sodium naphthalene sulfonate, etc.) are used. Used as an anion-providing compound.
[0074]
Among organic sulfonate anions, more effective dopants include one or more sulfoanion groups (-SO_Three ^-) And a sulfoquinone compound having a quinone structure and an anthracene sulfonate anion.
[0075]
As the basic skeleton of the sulfoquinone anion of the sulfoquinone compound, p-benzoquinone, o-benzoquinone, 1,2-naphthoquinone, 1,4-naphthoquinone, 2,6-naphthoquinone, 9,10-anthraquinone, 1,4-anthraquinone, 1,2-anthraquinone, 1,4-chrysenequinone, 5,6-chrysenequinone, 6,12-chrysenequinone, acenaphthoquinone, acenaphthenequinone, camphorquinone, 2,3-bornanedione, 9,10-phenanthrenequinone, 2,7- Examples include pyrenequinone.
[0076]
When the counter electrode (counter electrode) is solid, a conductor layer may be provided thereon in order to improve electrical contact with an external lead (for example, a lead frame) used as desired.
[0077]
The conductor layer can be formed by, for example, solidifying a conductive paste, plating, metal deposition, a heat-resistant conductive resin film, or the like. As the conductive paste, a silver paste, a copper paste, an aluminum paste, a carbon paste, a nickel paste, and the like are 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. Moreover, aluminum, nickel, copper, silver etc. are mentioned as a vapor deposition metal.
[0078]
Specifically, for example, a carbon paste and a silver paste are sequentially laminated on the second electrode and sealed with a material such as an epoxy resin to constitute a capacitor. This capacitor is sintered together with a niobium sintered body containing neodymium-niobium mononitride crystal, or later welded niobium, niobium alloy, niobium containing niobium mononitride crystal, one A niobium alloy containing a niobium nitride crystal or a tantalum lead may be included.
[0079]
The capacitor of the present invention having the above-described configuration can be made into a capacitor product for various uses by, for example, a resin mold, a resin case, a metallic outer case, resin dipping, and a laminate film.
[0080]
Further, when the counter electrode is liquid, the capacitor composed of the two electrodes and the dielectric is housed in, for example, a can electrically connected to the counter electrode to form a capacitor. In this case, the electrode side of the niobium sintered body containing neodymium-niobium mononitride crystal is the above-described niobium, niobium alloy, niobium containing niobium mononitride crystal, niobium alloy containing niobium mononitride crystal. Alternatively, it is designed to be insulated from the can by an insulating rubber or the like while being led out through the tantalum lead.
[0081]
As described above, by producing a sintered body for a capacitor using the niobium alloy manufactured according to the embodiment of the present invention described above, and manufacturing a capacitor from the sintered body, the leakage current value is small, high temperature characteristics and heat resistance characteristics. Thus, it is possible to obtain a highly reliable capacitor that satisfies both of the requirements.
[0082]
In addition, the capacitor of the present invention has a larger capacitance than the conventional tantalum capacitor, and a smaller capacitor product can be obtained.
The capacitor of the present invention having these characteristics is, for example, a bypass capacitor in an analog circuit and a digital circuit, an application as a coupling capacitor, an application as a large-capacity smoothing capacitor used in a power supply circuit, and a conventional tantalum capacitor. It can be applied to other uses.
[0083]
In general, such a capacitor is frequently used in an electronic circuit. Therefore, if the capacitor of the present invention is used, restrictions on the arrangement of electronic components and exhaust heat are alleviated, and a highly reliable electronic circuit is accommodated in a narrower space than before. be able to. Furthermore, if the capacitor of the present invention is used, electronic devices that are smaller and more reliable than conventional devices, for example, computer peripheral devices such as computers and PC cards, mobile devices such as mobile phones, home appliances, in-vehicle devices, artificial satellites, communication Equipment etc. can be obtained.
[0084]
【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.
[0085]
In addition, the measurement and evaluation methods for physical properties and the like in each example are as follows.
(1) Content of niobium mononitride crystal in niobium alloy containing niobium mononitride crystal
After mixing the crystal of known mass with the niobium mononitride crystal and niobium alloy, it was calculated from the calibration curve created from the 2θ diffraction intensity when X-ray diffraction measurement was performed and the mixed mass.
(2) Content of alloy components other than niobium in niobium alloy containing niobium mononitride crystal
It was determined by atomic absorption analysis, ICP emission analysis or ICP mass spectrometry.
[0086]
(3) Capacitance measurement
At room temperature, an LCR measuring instrument (Precision LCR meter HP4284A type) manufactured by Hewlett-Packard Co. was connected between the terminals of the manufactured chip, and the capacity at 120 Hz was defined as the capacity of the chip processed capacitor.
[0087]
(4) Capacitor leakage current measurement
At room temperature, the rated voltage (2.5V, 4V, 6.3V, 10V, 16V, 25V, etc.) of direct current close to about 1/3 to about 1/4 of the formation voltage (DC, 20V) at the time of dielectric fabrication The current value measured after the voltage (6.3 V) was continuously applied for 1 minute between the terminals of the fabricated chip was taken as the leakage current value of the capacitor processed into the chip.
[0088]
(5) High temperature characteristics of capacitors
In a 105 ° C. atmosphere, the capacitor was allowed to stand for 2000 hours with a 4 V voltage applied, and then returned to room temperature.₀) / C is defined as a high temperature characteristic, and a product in which this ratio is within ± 20% is judged as a non-defective product and evaluated by the ratio of the number of samples to the good product. The number of samples was 50 in each example.
[0089]
(6) Heat resistance of capacitors
The capacitor was mounted on a 1.5 mm thick laminated substrate together with solder, passed through a 230 ° C. reflow furnace over 30 seconds, and this was repeated three times. Usually, the capacitor is heated about 230 ° C. × 30 seconds × 3 times when passing through the reflow furnace, and has a practical thermal history (for example, soldering of components mounted on the surface of the substrate, soldering mounted on the back surface of the substrate, Evaluation is made for three soldering heat histories when soldering the retrofitted parts.
[0090]
The LC value before passing through the reflow furnace and after passing three times was measured at a rating of 6.3 V, and those having an LC value of 0.05 CV μA or less were judged as non-defective products and evaluated by the ratio of the number of samples to the number of good products. The number of samples was 50 in each example.
[0091]
Method for making sintered body 1:
Using 198 g of niobium ingot and 2 g of zirconium powder, a zirconium-containing niobium ingot (alloy) containing 1 atomic% of zirconium was produced by arc melting. 150 g of this ingot was put into a reaction vessel made of SUS304, and hydrogen was continuously introduced at 400 ° C. for 10 hours. After cooling, the hydrogenated zirconium-containing niobium mass was placed in a SUS304 pot containing SUS balls and ground for 10 hours. Next, a 20% by volume slurry of this hydride with water and a zirconia ball were placed in a spike mill made of SUS304, and wet pulverized for 7 hours. This slurry was centrifuged and decanted to obtain a pulverized product. 1.33 × 10 crushed material²It dried under reduced pressure on conditions of Pa and 50 degreeC. Subsequently, the zirconium hydride-containing niobium powder was 1.33 × 10^-2Heating was performed at Pa and 400 ° C. for 1 hour for dehydrogenation. The average particle diameter of the produced zirconium-containing niobium powder was 1 μm, and the zirconium content was 1 atomic% (1 mass%).
[0092]
100 g of this zirconium-containing niobium powder and 100 g of niobium mononitride crystals having an average particle diameter of 0.8 μm are placed in a SUS304 pot together with zirconia balls, and further added with 200 g of ion-exchanged water and rotated at a speed of 40 times per minute. Mixed for 3 hours. This slurry is 1.33 × 10²It dried under reduced pressure on conditions of Pa and 50 degreeC. Subsequently, the mixed powder of zirconium-containing niobium powder and niobium mononitride crystals placed in a niobium bat was placed in a sintering furnace, and the inside of the sintering system was replaced with argon.^-3Granulation was performed at 1100 ° C. under reduced pressure of Pa. Thereafter, this granulated mass was crushed to obtain a granulated powder having an average particle size of 110 μm. This granulated powder had a zirconium content of 0.5% by mass and a niobium mononitride crystal content of 50% by mass.
[0093]
The obtained zirconium-niobium mononitride crystal-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 cm × 0.18 cm × 0.45 cm. .
Next, these molded bodies were put into 4 × 10^-3The sintered body of the example was obtained by being left at 1200 ° C. for 30 minutes under reduced pressure of Pa.
[0094]
Method 2 for producing a sintered body:
9200 g of niobium pellets and 92 g of zirconium pellets were mixed well, and a zirconium-containing niobium ingot (alloy) containing 1 atomic% of zirconium was prepared by an electron beam melting method. 5000 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 mass was placed in a SUS304 pot containing SUS balls and ground for 10 hours. Next, a 20% by volume slurry of this hydride with water and zirconia balls were placed in a spike mill made of SUS304, and wet pulverized for 10 hours. This slurry was centrifuged and decanted to obtain a pulverized product. 1.33 × 10 crushed material²It dried under reduced pressure on conditions of Pa and 50 degreeC. Subsequently, the zirconium hydride-containing niobium powder was 1.33 × 10^-2Heating was performed at Pa and 400 ° C. for 1 hour for dehydrogenation. The produced zirconium-containing niobium powder had an average particle size of 0.9 μm and a zirconium content of 1 atomic% (1% by mass). Subsequently, the zirconium-containing niobium powder placed in a niobium bat was placed in a sintering furnace, and the inside of the sintering system was replaced with argon.^-3Granulation was performed at 1100 ° C. under reduced pressure of Pa. Thereafter, this granulated mass was crushed to obtain granulated powder having an average particle size of 90 μm. The zirconium content of this granulated powder was 1% by mass.
[0095]
This zirconium-containing niobium granulated powder was placed in a molybdenum reaction vessel, and the inside of the reaction vessel was sufficiently purged with nitrogen. After that, nitrogen was allowed to flow, and heating was continued at 580 ° C. for 5 hours for nitriding. After cooling to room temperature, the inside of the reaction vessel was sufficiently substituted with Ar, and then heated at 950 ° C. for 8 hours to change into niobium mononitride crystals. After cooling to room temperature, a niobium granulated powder containing zirconium-niobium mononitride crystals was obtained.
The zirconium content in the niobium granulated powder containing the zirconium-niobium mononitride crystal was 0.9% by mass, and the content of the niobium mononitride crystal was 55% by mass.
[0096]
The obtained zirconium-niobium mononitride crystal-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 cm × 0.18 cm × 0.45 cm. .
Next, these molded bodies were put into 4 × 10^-3The sintered body of the example was obtained by being left at 1200 ° C. for 30 minutes under reduced pressure of Pa.
[0097]
Method 3 for creating a sintered body:
In 2000 g of potassium fluoride niobate sufficiently dried under reduced pressure at 80 ° C. in a nickel crucible, 10 times the molar amount of sodium fluoride potassium niobate was charged and subjected to a reduction reaction at 1000 ° C. for 20 hours in an argon atmosphere. After the reaction, the reaction mixture was cooled, the reduced product was washed with water, then washed with 95% sulfuric acid and water successively, and then dried under reduced pressure. Further, after pulverizing for 10 hours using a ball mill of an alumina pot containing silica alumina balls, the pulverized product was immersed and stirred in a 3: 2 (mass ratio) mixed solution of 50% nitric acid and 10% hydrogen peroxide. Thereafter, the product was sufficiently washed with water until the pH reached 7, and then dried under reduced pressure. The average particle size of the produced niobium powder was 0.9 μm.
[0098]
500 g of this niobium powder was put into a molybdenum reaction vessel, and the inside of the reaction vessel was sufficiently purged with nitrogen, and then heated at 500 ° C. for 10 hours while flowing nitrogen, followed by nitriding. After cooling to room temperature, the inside of the reaction vessel was sufficiently substituted with Ar and heated at 800 ° C. for 20 hours to change into niobium mononitride crystals. After cooling to room temperature, niobium powder containing niobium mononitride crystals was obtained.
[0099]
500 g of niobium powder containing the niobium mononitride crystal and 10 g of zirconium hydride having an average particle size of 0.9 μm are placed in a SUS304 pot together with zirconia balls, and 200 g of ion-exchanged water is added, and the speed is 20 times per minute. And mixed for 5 hours. This slurry is 1.33 × 10²It dried under reduced pressure on conditions of Pa and 50 degreeC. Subsequently, after putting this mixed powder of niobium powder containing zirconium hydride and niobium mononitride crystals into a niobium bat, the bat was put into a sintering furnace and the inside of the sintered system was replaced with argon. × 10^-3Granulation was performed at 1150 ° C. under reduced pressure of Pa. Thereafter, this granulated mass was crushed to obtain granulated powder having an average particle size of 150 μm.
The zirconium content in the granulated powder of niobium containing the zirconium-niobium mononitride crystal was 1.8% by mass, and the content of the niobium mononitride crystal was 25% by mass.
[0100]
The obtained zirconium-niobium mononitride crystal-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 cm × 0.18 cm × 0.45 cm. .
Next, these molded bodies were put into 4 × 10^-3The sintered body of the example was obtained by being left at 1200 ° C. for 30 minutes under reduced pressure of Pa.
[0101]
Sintered body preparation method 4:
500 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 20% by volume slurry of this hydride with water and a zirconia ball were placed in a spike mill made of SUS304, and wet pulverized for 7 hours. This slurry was centrifuged and decanted to obtain a pulverized product. 1.33 × 10 crushed material²It dried under reduced pressure on conditions of Pa and 50 degreeC.
[0102]
Subsequently, the niobium hydride powder was 1.33 × 10^-2Heating was performed at Pa and 400 ° C. for 1 hour for dehydrogenation. The average particle size of the produced niobium powder was 1 μm. 4 × 10 of this niobium powder^-3Granulation was performed at 1100 ° C. under reduced pressure of Pa. Thereafter, the granulated mass was crushed to obtain granulated powder having an average particle size of 100 μm.
[0103]
The niobium granulated powder thus obtained was molded together with a 0.3 mmφ niobium wire to produce a molded body (approximately 0.1 g) of approximately 0.3 cm × 0.18 cm × 0.45 cm.
Next, these molded bodies were put into 4 × 10^-3The sintered compact of the comparative example was obtained by leaving it to stand at 1200 ° C. for 30 minutes under reduced pressure of Pa.
[0104]
Method 5 for making a sintered body:
In 2000 g of potassium fluoride niobate sufficiently dried under reduced pressure at 80 ° C. in a nickel crucible, 10 times the molar amount of sodium fluoride potassium niobate was charged and subjected to a reduction reaction at 1000 ° C. for 20 hours in an argon atmosphere. After the reaction, the reaction mixture was cooled, the reduced product was washed with water, then washed with 95% sulfuric acid and water successively, and then dried under reduced pressure. Further, after pulverizing for 10 hours using a ball mill of an alumina pot containing silica alumina balls, the pulverized product was immersed and stirred in a 3: 2 (mass ratio) mixed solution of 50% nitric acid and 10% hydrogen peroxide. Thereafter, the product was sufficiently washed with water until the pH reached 7, and then dried under reduced pressure. The average particle size of the produced niobium powder was 0.9 μm. 4 × 10 of this niobium powder^-3Granulation was performed at 1100 ° C. under reduced pressure of Pa. Thereafter, the granulated mass was crushed to obtain granulated powder having an average particle size of 100 μm.
[0105]
The niobium granulated powder thus obtained was molded together with a 0.3 mmφ niobium wire to produce a molded body (approximately 0.1 g) of approximately 0.3 cm × 0.18 cm × 0.45 cm.
Next, these molded bodies were put into 4 × 10^-3The sintered compact of the comparative example was obtained by leaving it to stand at 1200 ° C. for 30 minutes under reduced pressure of Pa.
[0106]
Capacitor creation method 1:
50 sintered bodies obtained by the same method as the method 2 for preparing sintered bodies were prepared. These sintered bodies were electrolytically oxidized for 6 hours 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 as a counter electrode layer on the dielectric oxide film. Subsequently, 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.
[0107]
Capacitor creation method 2:
50 sintered bodies obtained by the same method as the method 2 for preparing sintered bodies were prepared. These sintered bodies were electrolytically oxidized for 6 hours 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) mixed solution of 35% lead acetate aqueous solution and 35% ammonium persulfate aqueous solution, the reaction at 40 ° C. for 1 hour was repeated to form a counter electrode layer on the dielectric oxide film. A mixed layer of lead dioxide and lead sulfate was formed. Subsequently, 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.
[0108]
Capacitor creation method 3:
50 sintered bodies obtained by the same method as the method 2 for preparing sintered bodies were prepared. These sintered bodies were electrolytically oxidized for 6 hours using a 0.1% phosphoric acid aqueous solution at a voltage of 20 V to form a dielectric oxide film on the surface. Next, an equivalent mixture of a 10% aqueous solution of ammonium persulfate and an aqueous solution of 0.5% anthraquinone sulfonic acid is brought into contact with the dielectric oxide film, and then contacted with pyrrole vapor is performed at least five times to form polypyrrole. A counter electrode (counter electrode) was formed.
[0109]
Subsequently, 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.
[0110]
Capacitor creation method 4:
50 sintered bodies obtained by the same method as the method 2 for preparing sintered bodies were prepared. These sintered bodies were electrolytically oxidized for 6 hours using a 0.1% phosphoric acid aqueous solution at a voltage of 20 V to form a dielectric oxide film on the surface. Next, the niobium sintered body was dipped in an aqueous solution (solution 1) containing 25% by mass of ammonium persulfate and then pulled up, dried at 80 ° C. for 30 minutes, and then the sintered body on which the dielectric was formed was converted into 3,4-ethylene. After dipping in an isopropanol solution (solution 2) containing 18% by mass of dioxythiophene, the film was pulled up and allowed to stand in an atmosphere at 60 ° C. for 10 minutes for oxidative polymerization. This was again immersed in solution 1 and further treated in the same manner as described above. The operation from immersion in solution 1 to oxidative polymerization was repeated 8 times, followed by washing with warm water at 50 ° C. for 10 minutes, and drying at 100 ° C. for 30 minutes, whereby conductive poly (3, A counter electrode (counter electrode) composed of 4-ethylenedioxythiophene) was formed.
[0111]
Subsequently, 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.
[0112]
Examples 1-40:
As shown in Table 2, the sintered body was prepared by changing the content of the niobium mononitride crystal and the content of the alloy component in the same manner as the method 1 or 2 of preparing the sintered body. Capacitors were prepared for 50 sintered bodies using any one of the capacitor preparation methods 1 to 4. The capacitors (50) were evaluated for heat resistance and high temperature characteristics. The results are shown in Table 2.
[0113]
Examples 41-60:
Sintered using niobium powder containing niobium mononitride crystals and additives of the types and amounts shown in Table 3 (elements or their compounds as alloying components) in the same manner as in preparation method 3 of the sintered body. Created the body. Capacitors were prepared for 50 sintered bodies using any one of the capacitor preparation methods 1 to 4. The capacitors (50) were evaluated for heat resistance and high temperature characteristics. The results are shown in Table 3.
[0114]
Comparative Examples 1-8:
For comparison with Examples 1 to 60, a niobium sintered body containing no niobium mononitride crystal and the other alloy component was prepared by a method similar to the method 4 or 5 for forming a sintered body. Capacitors were prepared using any one of the capacitor preparation methods 1 to 4 for 50 sintered bodies. The capacitors (50) were evaluated for heat resistance and high temperature characteristics. The results are shown in Tables 2 and 3.
[0115]
[Table 2]

[0116]
[Table 3]

[0117]
【The invention's effect】
It contains at least one element selected from the group consisting of groups 2 to 16 of the periodic table as an alloy component, and further contains niobium mononitride (Nb₂A capacitor containing N) crystals is prepared and a capacitor is prepared using the sintered body, whereby a capacitor having improved high temperature characteristics and heat resistance can be obtained.

Claims (15)

A niobium alloy containing at least one element selected from the group consisting of groups 2 to 16 of the periodic table as an alloy component in an alloy of 10 atomic% or less and containing a niobium mononitride crystal,
The alloys include Zr, W, Y, La, Ce, Nd, Sm, Gd, Dy, Ho, Er, Yb, Ti, Hf, V, Ta, Mo, Mn, Ag, Zn, B, Al, Sb, Containing at least one element selected from the group consisting of Mg, Si, Ba, and S as an alloy component in an alloy of 0.01 atomic% or more,
The niobium mononitride crystal is contained in the alloy in an amount of 0.1 to 70% by mass,
A niobium alloy for capacitors, wherein the balance is niobium and inevitable impurities.   Alloy components are Zr, W, Y, La, Ce, Nd, Sm, Gd, Dy, Ho, Er, Yb, Ti, Hf, V, Ta, Mo, Mn, Ag, Zn, B, Al, Sb, Si 2. The niobium alloy for capacitors according to claim 1, which is at least one element selected from the group consisting of S and S. 3.   The niobium alloy for capacitors according to claim 1 or 2, wherein the niobium alloy is a powder having an average particle size of 0.05 to 5 µm. The niobium alloy for capacitors according to any one of claims 1 to 3, wherein the niobium alloy has a BET specific surface area of 0.5 to 40 m ² / g.   Niobium composition powder for a capacitor comprising an element or compound thereof, niobium or a niobium compound, and a niobium mononitride crystal as an alloy component of at least one niobium alloy selected from the group consisting of groups 2 to 16 of the periodic table A niobium composition powder for a capacitor having the alloy composition according to claim 1 when the composition powder is an alloy. Alloy components are Zr, W, Y, La, Ce, Nd, Sm, Gd, Dy, Ho, Er, Yb, Ti, Hf, V, Ta, Mo, Mn, Ag, Zn, B, Al, Sb, Si The niobium composition powder for capacitors according to claim 5 , which is at least one element selected from the group consisting of S and S. A niobium granule for a capacitor obtained by granulating the niobium alloy powder according to any one of claims 1 to 4 . A niobium granule for a capacitor obtained by granulating the niobium composition powder according to claim 5 or 6 . The niobium granule for capacitors according to claim 7 or 8 , wherein the niobium granule has an average particle size of 10 to 500 µm. The sintered compact obtained by sintering the niobium alloy of any one of Claims 1 thru | or 4 . A sintered body obtained by sintering the niobium composition powder according to claim 5 or 6 . A sintered body obtained by sintering the niobium granule according to any one of claims 7 to 9 . The sintered body according to any one of claims 10 to 12 is used as one electrode, and includes a dielectric formed on the surface of the sintered body and a counter electrode provided on the dielectric. Capacitor. An electronic circuit using the capacitor according to claim 13 . An electronic device using the capacitor according to claim 13 .