JP3615947B2

JP3615947B2 - Dielectric porcelain composition and porcelain capacitor

Info

Publication number: JP3615947B2
Application number: JP29936998A
Authority: JP
Inventors: 洋一水野; 康之猪又; 広一茶園
Original assignee: Taiyo Yuden Co Ltd
Current assignee: Taiyo Yuden Co Ltd
Priority date: 1998-10-21
Filing date: 1998-10-21
Publication date: 2005-02-02
Anticipated expiration: 2018-10-21
Also published as: JP2000128635A

Description

【０００１】
【発明の属する技術分野】
この発明は、誘電体磁器組成物、特に数１００ＭＨｚ〜数ＧＨｚの高周波領域で使用される０．０１ｐＦ〜３０ｐＦ程度の低容量の磁器コンデンサの誘電体層を形成するのに適した誘電体磁器組成物とこの誘電体磁器組成物を用いて形成した磁器コンデンサに関するものである。
【０００２】
【従来の技術】
高周波領域で使用される低容量の磁器コンデンサの誘電体層の材料としては、従来、ＴｉＯ_２系材料、ＣａＴｉＯ_３系材料、ＬａＴｉＯ_３系材料、ＣａＺｒＯ_３系材料、ＭｇＴｉＯ_３系材料等の低誘電率の誘電体磁器組成物が用いられていた。そして、これらの誘電体磁器組成物を用いた磁器コンデンサの内部電極の材料としては、Ｐｔ，Ｐｄ，Ｃｕ，Ｎｉ等の金属が用いられていた。
【０００３】
ただ、これらの内部電極の材料中、Ｐｔは高価な金属なので、これを内部電極の材料として使用すると磁器コンデンサの製造コストを高めるという欠点があった。また、Ｃｕ，Ｎｉ等の卑金属は焼成中に酸化し易いので、これを内部電極の材料として使用する場合は焼成雰囲気の制御をしなければならず、この点で磁器コンデンサの製造コストを高めるという欠点があった。
【０００４】
本件特許出願人はこれらの欠点を解消する誘電体磁器組成物として、特願平８−１８８０９４号（特開平１０−１７３５９号）特許出願及び特願平９−８４５２７号特許出願で、珪酸マグネシウム・亜鉛［（Ｍｇ_ａＺｎ_{（１−ａ）} ）_ｘＳｉＯ_ｘ＋２］、アルミナ［Ａｌ_２Ｏ_３］、及びチタン酸ストロンチウム［ＳｒＴｉＯ_３］系の誘電体磁器組成物を提案した。
【０００５】
この提案に係る誘電体磁器組成物は、数１００ＭＨｚ〜数ＧＨｚの高周波領域においてＱ値が高く、損失、リーク電流の小さな低容量（０．０１ｐＦ〜３０ｐＦ）の磁器コンデンサを得ることができるという利点を有するものである。また、これらの誘電体磁器組成物は、１１００℃以下の温度で焼結させることができるので、デラミネーション等の構造欠陥を抑制できるという利点を有するものである。
【０００６】
【発明が解決しようとする課題】
ところで、企業間における技術競争は厳しいものがあり、電子機器回路の特性も更なる向上が求められ、そのために、上記提案の誘電体磁器組成物についても磁器コンデンサのＱ値を更に向上させるものが求められている。
【０００７】
磁器コンデンサのＱ値を高めるためには、内部電極を比抵抗値の小さな金属材料で形成する方法が考えられる。そして、比抵抗値の小さな金属材料としてはＡｇが挙げられる。
【０００８】
しかし、Ａｇは融点が９６０℃と、上記誘電体磁器組成物の焼結温度１０５０〜１１００℃より低いので、焼成の際に積層体内の内部電極が溶融してしまい、このままでは内部電極の材料として使用することができない。
【０００９】
この発明は、９５０℃以下の温度で焼成でき、Ｐｄよりも比抵抗の小さな、周波数特性の良好なＡｇを内部電極の材料として使用してもデラミネーションを生じさせず、低誘電率（ε_ｒ：１５以下）で、積層磁器コンデンサにした場合にリーク電流が低い（１２５℃−６００Ｖで１．０μＡ以下）誘電体磁器組成物とこの誘電体磁器組成物を用いた磁器コンデンサを提供することを目的とする。
【００１０】
【課題を解決するための手段】
この発明に係る誘電体磁器組成物は、一般式Ｘ（Ｍｇ_ａＺｎ_{（１−ａ）} ）_ＸＳｉＯ_Ｘ＋２ −ＹＡｌ_２Ｏ_３ −ＺＳｒＴｉＯ_３で表わされる主成分と、Ｎｂ，Ｔａ，及びＷから選択された１種又は２種以上の元素の化合物からなる第一添加成分と、Ｖ，Ｃｒ，Ｍｎ，Ｆｅ，Ｃｏ，Ｎｉ，及びＣｕから選択された１種又は２種以上の元素の化合物からなる第二添加成分を含有し、
前記主成分を構成する珪酸マグネシウム・亜鉛［（Ｍｇ_ａＺｎ_{（１−ａ）} ）_ＸＳｉＯ_Ｘ＋２］、アルミナ［Ａｌ_２Ｏ_３］及びチタン酸ストロンチウム［ＳｒＴｉＯ_３］のモル比［％］が、これら３種の化合物のモル比（Ｘ，Ｙ，Ｚ）を示す３成分組成図に於いて、
Ａ（９４．９，０．１，５．０）
Ｂ（８５．０，１０．０，５．０）
Ｃ（６５．０，１０．０，２５．０）
Ｄ（６５．０，０．１，３４．９）
で示される各点Ａ〜Ｄを頂点とする多角形で囲まれた範囲にあり、
前記主成分を表す一般式中のａ及びｘの値が、
０．１≦ａ≦０．８０
０．６７≦ｘ≦１．３０
の範囲にあり、
前記第一添加成分がＮｂＯ_５／２，ＴａＯ_５／２，又はＷＯ_３に換算して０．０１〜０．２モル％含有され、
前記第二添加成分がＶＯ_５／２，ＣｒＯ_３／２，ＭｎＯ_３／２，ＦｅＯ_３／２，ＣｏＯ_３／２，ＮｉＯ，又はＣｕＯに換算して０．０５〜２．０モル％含有されているものである。
【００１１】
ここで、ＭＺＳ，Ａｌ_２Ｏ_３及びＳｒＴｉＯ_３のモル比［％］を上記の範囲としたのは、これらの化合物が上記の範囲にある場合は所望の電気的特性の誘電体磁器組成物が得られるが、これらの化合物が上記の範囲を逸脱すると、９５０℃以下の焼成で緻密な焼結体が得られなくなったり、誘電率が１５以上と大きくなり過ぎ、また、温度係数がマイナス側に大きくなり過ぎるからである。
【００１２】
また、ａの値を０．１〜０．８０の範囲としたのは、ａの値がこの範囲にある場合は所望の電気的特性の誘電体磁器組成物が得られるが、ａの値が０．１未満になると、焼結体の内部にポアが多く存在してしまい、緻密な焼結体が得られなくなり、ａの値が０．８を超えると、９５０℃の焼成で緻密な焼結体が得られなくなるからである。
【００１３】
また、ｘの値を０．６７〜１．３０の範囲としたのは、ｘの値がこの範囲にある場合は、所望の電気的特性の誘電体磁器組成物が得られるが、ｘの値が０．６７未満になると、焼成の際に融着したり、焼成適正温度幅が非常に狭くなり、焼結体中にポアが多く生成してしまったり、Ｑ値が１０００より小さくなってしまい、ｘの値が１．３０を超えると、９５０℃の焼成で緻密な焼結体が得られなくなるからである。
【００１４】
前記第一添加成分をＮｂＯ_５／２，ＴａＯ_５／２又はＷＯ_３に換算して０．０１〜０．２モル％の範囲としたのは、これらの添加成分がこれらの範囲にある場合は信頼性の高い（リーク電流の少ない）所望の電気的特性の誘電体磁器組成物が得られるが、これらの添加成分が０．０１モル％未満になると、リーク電流が１．０μＡ以上となり、０．２モル％を越えると９５０℃以下の焼成で、緻密な焼結体が得られなくなるからである。
【００１５】
前記第二添加成分をＶＯ_５／２，ＣｒＯ_３／２，ＭｎＯ_３／２，ＦｅＯ_３／２，ＣｏＯ_３／２，ＮｉＯ又はＣｕＯに換算して０．０５〜２．０モル％の範囲としたのは、これらの添加成分がこれらの範囲にある場合は低温焼成で所望の電気的特性の誘電体磁器組成物が得られるが、これらの成分が０．０５モル％未満になるか、２．０モル％を超えると緻密な焼結体が得られなくなるからである。
【００１６】
なお、前記第一添加成分及び第二添加成分は、単独で使用しても、また複数種を同時に使用しても同様の結果が得られる。また、これらの添加成分は酸化物だけでなく、焼成して酸化物となり得る炭酸塩やその他の可溶性の合成物を用いても良い。
【００１７】
また、ＭＺＳ，Ａｌ_２Ｏ_３及びＳＴからなる混合物の仮焼は行っても、行わなくても、所望の特性は得られるが、仮焼の有無で電気的特性は変化する。また、仮焼により添加成分と主成分、或いは添加成分同志で反応が起こり、結晶系が変化し、急激に収縮が生じたり、収縮率が大きくなる場合、仮焼は有効である。すなわち、仮焼はデラミネーション、クラック等の構造欠陥の抑制に有効である。
【００１８】
また、この発明に係る磁器コンデンサは、上記の誘電体磁器組成物を誘電体層として用いたものである。ここで、内部電極の材料としてはＡｇが好ましい。磁器コンデンサは単層タイプのもの及び積層タイプのもののいずれにも適用できる。
【００１９】
また、この発明に係る磁器コンデンサは、低周波領域でも十分使用できるが、特に、数１００ＭＨｚ〜数ＧＨｚの高周波領域で使用される０．０１ｐＦ〜３０ｐＦ程度の低容量の磁器コンデンサとして用いるのに好適である。
【００２０】
【実施例】
まず、ＭｇＯ，ＺｎＯ及びＳｉＯ_２を表１〜表５に示すような比率で秤量し、これらをボールミルに入れ、湿式で１５時間粉砕混合し、これらの混合物からなる泥漿を得た。そして、この泥漿を取り出して濾過し、ケーキの部分を乾燥器に入れ、１５０℃で充分に乾燥させ、混合物の粉末を得た。
【００２１】
次に、この混合物の粉末を加熱炉に入れ、１１００℃で仮焼し、混合物を構成している化合物を相互に反応させてＭＺＳを得た。なお、ここでは混合物を１１００℃で仮焼しているが、仮焼温度は９００〜１２００℃の範囲で変更可能である。また、この仮焼は必ずしもしなくてよく、試料Ｎｏ．８５〜８９のものはこの仮焼をしなかった。
【００２２】
次に、このＭＺＳをボールミルに入れ、湿式で充分に粉砕してＭＺＳの泥漿を得た。そして、この泥漿を取り出して濾過し、ケーキの部分を乾燥器に入れ、１５０℃で充分に乾燥させ、ＭＺＳの粉末を得た。
【００２３】
次に、ＭＺＳ，Ａｌ_２Ｏ_３，ＳＴ，第一添加成分及び第二添加成分を表１〜表５に示すような比率で秤量し、これらをボールミルに入れ、湿式で充分に混合し、これらの混合物からなる泥漿を得た。そして、この泥漿を取り出して濾過し、ケーキの部分を乾燥器に入れ、１５０℃で充分に乾燥させ、混合物の粉末を得た。
【００２４】
次に、試料Ｎｏ．２４，８８のものについては、８００℃で２時間（８００／２）、試料Ｎｏ．８９のものについては、９００℃で２時間（９００／２）仮焼した。ここでは８００℃又は９００℃で２時間仮焼しているが、７００〜９００℃で２〜４時間の範囲で変更可能である。また、この仮焼も必須のものではなく、これらの試料Ｎｏ以外のものは仮焼しなかった。
【００２５】
次に、有機バインダを加えて造粒し、プレス成型して直径約１０ｍｍ、厚さ約０．５ｍｍの円板状の試料を作製し、この試料を９００〜９５０℃で１〜４時間焼成して焼結させ、Ａｇペーストを塗布し、７００℃で１５分間焼成して外部電極を形成させ、磁器コンデンサを形成した。
【００２６】
一方、混合物の粉末に有機溶剤、有機バインダー、可塑剤等を加えて混合し、スラリーとし、該スラリーよりドクターブレード法を用いて厚さ４０μｍのセラミックグリーンシートを得、このセラミックグリーンシートの表面にＡｇ電極ペーストを所定パターンに印刷し、これを交互に１１枚積層・圧着して１０層の積層体を作成し、得られた積層体を切断して複数のチップ積層体を得た。ここで、Ａｇペーストは、焼結を遅延させるための添加成分を多少混合したものを用いても良い。
【００２７】
次に、この試料を脱バインダー処理して、約９００〜９５０℃で１〜４時間焼成させ、得られた焼結体試料の両端部にＡｇペーストを塗布し、７００℃で１５分間焼成して外部電極を形成させ、積層磁器コンデンサを形成した（試料サイズ：１．０ｍｍ×０．５ｍｍ×０．５ｍｍ、有効交差面積：０．０５ｍｍ^２、誘電体一層当たりの厚み：３０μｍ）。
【００２８】
【表１】

【００２９】
【表２】

【００３０】
【表３】

【００３１】
【表４】

【００３２】
【表５】

【００３３】
次に、円板磁器コンデンサ及び積層磁器コンデンサについて、室温、ＨＰ４２８４Ａ、１ＭＨｚ、１Ｖ_ｒｍｓの条件でＣ，Ｑを求めた。誘電率、１５０℃における絶縁抵抗、誘電率の温度係数（２０℃を基準として８５℃の変化率）は、円板状磁器コンデンサから１０個平均として求めた。その結果は、表６〜表１０に示す通りであった。
【００３４】
なお、表６〜表１０における絶縁抵抗ρの数値、例えば９．１０Ｅ＋０６は９．１０×１０^６を表す。温度係数ＴＣＣは次の数１の式を用いて算出した。リーク電流は１２５℃のオイル中で、試料に６００ＶのＤＣを印加し、安定したときの電流値をデジタルマルチメータ（ＹＯＫＯＧＡＷＡ７５５２）を用いて測定した。
【００３５】
【数１】

【００３６】
【表６】

【００３７】
【表７】

【００３８】
【表８】

【００３９】
【表９】

【００４０】
【表１０】

【００４１】
表６〜表１０に示す結果から、次のことがわかる。すなわち、主成分を構成するＭＺＳ，Ａｌ_２Ｏ_３及びＳｒＴｉＯ_３のモル比［％］が、これら３種の化合物のモル比（Ｘ，Ｙ，Ｚ）の組成範囲を示す図１に於いて、
Ａ（９４．９，０．１，５．０）
Ｂ（８５．０，１０．０，５．０）
Ｃ（６５．０，１０．０，２５．０）
Ｄ（６５．０，０．１，３４．９）
で示される各点Ａ〜Ｄを頂点とする多角形で囲まれた範囲にある場合、試料Ｎｏ．１７〜２４，５０〜５２，７８，７９，８３〜８９に示すように、所望の電気的特性の誘電体磁器組成物が得られるが、この範囲を逸脱すると、試料Ｎｏ．１，１６，５３，８０，８１に示すように、９５０℃以下の焼成で緻密な焼結体が得られなくなったり、試料Ｎｏ．８２に示すように誘電率が１５以上と大きくなり過ぎ、温度係数がマイナス側に大きくなり過ぎてしまう。
【００４２】
また、ａの値が、試料Ｎｏ．５６〜５８に示すように、０．１０〜０．８０の範囲にある場合、所望の電気的特性の誘電体磁器組成物が得られるが、試料Ｎｏ．５９に示すように、ａの値が０．１未満になると、焼結体内部にポアが多く存在しまい、緻密な焼結体が得られなくなり、また、試料Ｎｏ．５４，５５に示すように、ａの値が０．８より大きくなると、９５０℃の焼成で緻密な焼結体が得られなくなる。
【００４３】
また、ｘの値が、試料Ｎｏ．６１，６４に示すように、０．６７〜１．３０の範囲にある場合、所望の電気的特性の誘電体磁器組成物が得られるが、ｘの値が０．６７未満になると、焼結体が融着し易くなり、焼成適正温度幅が非常に狭くなり、焼結体中にポアが多く生成してしまったり、Ｑ値が１０００より小さくなり、また、試料Ｎｏ．６２，６３に示すように、ｘの値が１．３を超えると、９５０℃の焼成で緻密な焼結体が得られなくなる。
【００４４】
また、第一添加成分であるＮｂ，Ｔａ又はＷの化合物が、試料Ｎｏ．３，９，１１，１４に示すように、ＮｂＯ_５／２，ＴａＯ_５／２又はＷＯ_３に換算して０．０１〜０．２モル％の範囲にある場合、所望の電気的特性の誘電体磁器組成物が得られるが、試料Ｎｏ．２に示すように、０．０１モル％未満になるとリーク電流が１．０μＡ以上となり、試料Ｎｏ．１２，１３，１５に示すように、０．２モル％を超えると、９５０℃の焼成で緻密な焼結体が得られなくなる。Ｎｂ，Ｔａ又はＷの化合物は単独で添加してもよいし、試料Ｎｏ．７５，７７に示すように、複数種を同時に添加してもよい。
【００４５】
また、第二添加成分であるＶ，Ｃｒ，Ｍｎ，Ｆｅ，Ｃｏ，Ｎｉ又はＣｕの化合物が、試料Ｎｏ．３〜７，９，１１，１４，２６〜２８，３１〜３３，３６〜３８，４１〜４３，４６〜４８に示すように、ＶＯ_５／２，ＣｒＯ_３／２，ＭｎＯ_３／２，ＦｅＯ_３／２，ＣｏＯ_３／２，ＮｉＯ又はＣｕＯに換算して０．０５〜２．０モル％の範囲にある場合、所望の電気的特性の誘電体磁器組成物が得られるが、試料Ｎｏ．８，１０，２５，３０，３５，４０，４５に示すように、０．０５モル％未満になるか、２．０モル％を超えると緻密な焼結体が得られなくなる。Ｖ，Ｃｒ，Ｍｎ，Ｆｅ，Ｃｏ，Ｎｉ又はＣｕの化合物は単独で添加してもよいし、試料Ｎｏ．６６〜７３に示すように、複数種を同時に添加してもよい。
【００４６】
なお、ＭＺＳ，Ａｌ_２Ｏ_３及びＳＴからなる混合物の仮焼は行っても、行わなくても、所望の特性は得られるが、仮焼の有無で電気的特性は変化する。また、仮焼により、添加成分と主成分、或いは添加成分同志で反応が起こり、結晶系が変化し、急激に収縮が生じたり、収縮率が大きくなる場合、仮焼は有効である。すなわち、仮焼はデラミネーション、クラック等の構造欠陥の抑制に有効である。
【００４７】
この発明に従う誘電体磁器組成物、すなわち表１〜表５中で評価○となっている試料は、９５０℃以下の焼成で焼結でき、誘電率が１５以下と低く、Ｑ値が高く（１ＭＨｚで１０００以上）、１５０℃での抵抗率が高く（１．０×１０^３ＭΩｃｍ以上）、容量の温度係数が小さく、ＪＩＳ規格の
ＣＧ特性（ −３０〜＋３０［ｐｐｍ／℃］）
ＣＨ特性（ −６０〜＋６０［ｐｐｍ／℃］）
ＣＪ特性（−１２０〜＋１２０［ｐｐｍ／℃］）
ＰＨ特性（ −９０〜−２１０［ｐｐｍ／℃］）
ＲＨ特性（−１６０〜−２８０［ｐｐｍ／℃］）
ＳＨ特性（−２７０〜−３９０［ｐｐｍ／℃］）
を満足していることがわかる。
【００４８】
【発明の効果】
この発明によれば、数１００ＭＨｚ〜数ＧＨｚの高周波領域においてＱ値が高く、損失、リーク電流の小さな低容量（０．０１ｐＦ〜３０ｐＦ）の磁器コンデンサを得ることができるという効果がある。
【００４９】
また、この発明によれば、誘電体磁器組成物の焼結温度を９５０℃以下に低下させることができるので、デラミネーション等の構造欠陥を抑制でき、磁器コンデンサ製造の際における焼成のための電力費を低減でき、コストダウンを図ることができるという効果がある。
【００５０】
また、この発明によれば、内部電極の材料としてＰｄより安価なＡｇを使用することができるので、磁器コンデンサ製造のコストダウンを図ることができるという効果がある。
【図面の簡単な説明】
【図１】ＭＺＳ，Ａｌ_２Ｏ_３及びＳＴのモル比［％］を示す３成分組成図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dielectric ceramic composition, particularly a dielectric ceramic composition suitable for forming a dielectric layer of a low-capacity ceramic capacitor of about 0.01 pF to 30 pF used in a high frequency region of several hundred MHz to several GHz. And a ceramic capacitor formed by using the dielectric ceramic composition.
[0002]
[Prior art]
The dielectric layer of ceramic capacitors with low capacity used in a high frequency region, the conventional, TiO ₂ based materials, CaTiO ₃ based materials, LaTiO ₃ based materials, CaZrO ₃ based materials, low dielectric such as MgTiO ₃ based material Rate dielectric porcelain compositions were used. Metals such as Pt, Pd, Cu, and Ni have been used as materials for internal electrodes of ceramic capacitors using these dielectric ceramic compositions.
[0003]
However, among these internal electrode materials, since Pt is an expensive metal, there is a drawback in that if this is used as the internal electrode material, the manufacturing cost of the ceramic capacitor is increased. In addition, since base metals such as Cu and Ni are easily oxidized during firing, the firing atmosphere must be controlled when using this as a material for the internal electrode, which increases the production cost of the ceramic capacitor. There were drawbacks.
[0004]
As a dielectric ceramic composition that solves these drawbacks, the present patent applicant has filed Japanese Patent Application No. Hei 8-188094 (Japanese Patent Laid-Open No. 10-17359) and Japanese Patent Application No. Hei 9-84527. zinc _{_{_{[(Mg a Zn (1-}}} a)) x SiO x + 2], alumina _[Al _{2 O} 3], and proposed a dielectric ceramic composition of strontium titanate [SrTiO _3] system.
[0005]
The dielectric ceramic composition according to this proposal has an advantage that a low-capacitance (0.01 pF to 30 pF) ceramic capacitor having a high Q value in a high frequency region of several hundred MHz to several GHz and small loss and leakage current can be obtained. It is what has. Moreover, since these dielectric ceramic compositions can be sintered at a temperature of 1100 ° C. or less, they have the advantage that structural defects such as delamination can be suppressed.
[0006]
[Problems to be solved by the invention]
By the way, there are severe technological competitions between companies, and further improvement in the characteristics of electronic equipment circuits is required. For this reason, the proposed dielectric ceramic composition further improves the Q value of the ceramic capacitor. It has been demanded.
[0007]
In order to increase the Q value of the ceramic capacitor, a method of forming the internal electrode with a metal material having a small specific resistance value can be considered. And Ag is mentioned as a metal material with a small specific resistance value.
[0008]
However, since Ag has a melting point of 960 ° C., which is lower than the sintering temperature of 1050 to 1100 ° C. of the dielectric ceramic composition, the internal electrode in the laminated body melts during firing, and as it is, the material for the internal electrode Cannot be used.
[0009]
This invention can be fired at a temperature of 950 ° C. or lower, has a specific resistance lower than that of Pd, and has good frequency characteristics, so that no delamination occurs and low dielectric constant (ε _r 15 or less), and a multilayer ceramic capacitor having a low leakage current (1.0 μA or less at 125 ° C.-600 V) and a ceramic capacitor using the dielectric ceramic composition are provided. Objective.
[0010]
[Means for Solving the Problems]
The dielectric ceramic composition according to the invention, selected main component represented by the general formula _{_{_{_{X (Mg a Zn (1-}}}} a)) X SiO X + 2 -YAl 2 O 3 -ZSrTiO 3, Nb, Ta, and the W A first additive component composed of a compound of one or two or more elements and a compound of one or more elements selected from V, Cr, Mn, Fe, Co, Ni, and Cu Containing a second additive component,
The molar ratio [%] of magnesium silicate / zinc [(Mg _a Zn _(1-a) ) _X SiO _{X + 2} ], alumina [Al ₂ O ₃ ] and strontium titanate [SrTiO ₃ ] constituting the main components is In the three-component composition diagram showing the molar ratio (X, Y, Z) of the three compounds,
A (94.9, 0.1, 5.0)
B (85.0, 10.0, 5.0)
C (65.0, 10.0, 25.0)
D (65.0, 0.1, 34.9)
In a range surrounded by a polygon having the points A to D as vertices,
The values of a and x in the general formula representing the main component are
0.1 ≦ a ≦ 0.80
0.67 ≦ x ≦ 1.30
In the range of
The first additive component is contained in an amount of 0.01 to 0.2 mol% in terms of NbO _5/2 , TaO _5/2 , or WO ₃ ,
The second additive component is contained in an amount of 0.05 to 2.0 mol% in terms of VO _5/2 , CrO _3/2 , MnO _3/2 , FeO _3/2 , CoO _3/2 , NiO, or CuO. It is what.
[0011]
Here, the molar ratio [%] of MZS, Al ₂ O ₃ and SrTiO ₃ was set in the above range because when these compounds are in the above range, the dielectric ceramic composition having desired electrical characteristics is obtained. However, if these compounds deviate from the above range, a dense sintered body cannot be obtained by firing at 950 ° C. or lower, the dielectric constant becomes too large as 15 or more, and the temperature coefficient becomes negative. Because it becomes too big.
[0012]
In addition, the value of a is in the range of 0.1 to 0.80 because when the value of a is in this range, a dielectric ceramic composition having desired electrical characteristics can be obtained. If it is less than 0.1, there are many pores inside the sintered body, and a dense sintered body cannot be obtained. If the value of a exceeds 0.8, dense firing is performed at 950 ° C. This is because no union can be obtained.
[0013]
Also, the value of x is in the range of 0.67 to 1.30. When the value of x is in this range, a dielectric ceramic composition having desired electrical characteristics can be obtained. If it is less than 0.67, it will be fused at the time of firing, the appropriate temperature range for firing will be very narrow, many pores will be generated in the sintered body, and the Q value will be less than 1000 If the value of x exceeds 1.30, a dense sintered body cannot be obtained by firing at 950 ° C.
[0014]
The first additive component is in the range of 0.01 to 0.2 mol% in terms of NbO _5/2 , TaO _5/2 or WO ₃ when these additive components are in these ranges. A dielectric ceramic composition having desired electrical characteristics with high reliability (low leakage current) can be obtained. However, when these additive components are less than 0.01 mol%, the leakage current becomes 1.0 μA or more, and 0 This is because if it exceeds 2 mol%, a dense sintered body cannot be obtained by firing at 950 ° C. or lower.
[0015]
When the second additive component is converted to VO _5/2 , CrO _3/2 , MnO _3/2 , FeO _3/2 , CoO _3/2 , NiO or CuO, When these additive components are in these ranges, a dielectric ceramic composition having desired electrical characteristics can be obtained by low-temperature firing, but these components are less than 0.05 mol%, or 2 This is because if it exceeds 0.0 mol%, a dense sintered body cannot be obtained.
[0016]
In addition, the said 1st addition component and the 2nd addition component can use the same result, even if it uses individually or it uses multiple types simultaneously. In addition to these oxides, these additive components may be carbonates or other soluble compounds that can be baked to become oxides.
[0017]
Moreover, although the desired characteristics can be obtained with or without calcination of the mixture composed of MZS, Al ₂ O ₃ and ST, the electrical characteristics change depending on the presence or absence of calcination. In addition, when calcining causes a reaction between the additive component and the main component, or between the additive components, the crystal system changes, and a rapid contraction occurs or the shrinkage rate increases, the calcining is effective. That is, calcination is effective for suppressing structural defects such as delamination and cracks.
[0018]
A ceramic capacitor according to the present invention uses the above dielectric ceramic composition as a dielectric layer. Here, Ag is preferable as the material of the internal electrode. The ceramic capacitor can be applied to both a single layer type and a multilayer type.
[0019]
Further, the ceramic capacitor according to the present invention can be sufficiently used in a low frequency region, but is particularly suitable for use as a low-capacity ceramic capacitor of about 0.01 pF to 30 pF used in a high frequency region of several hundred MHz to several GHz. It is.
[0020]
【Example】
First, MgO, ZnO, and SiO ₂ were weighed at the ratios shown in Tables 1 to 5, put in a ball mill, and pulverized and mixed for 15 hours in a wet manner to obtain a slurry consisting of these mixtures. The slurry was taken out and filtered, and the cake portion was put in a drier and dried sufficiently at 150 ° C. to obtain a powder of the mixture.
[0021]
Next, the powder of this mixture was put into a heating furnace and calcined at 1100 ° C., and the compounds constituting the mixture were reacted with each other to obtain MZS. In addition, although the mixture is calcined at 1100 ° C. here, the calcining temperature can be changed in the range of 900 to 1200 ° C. Further, this calcination is not necessarily performed. No. 85-89 did not perform this calcination.
[0022]
Next, this MZS was put in a ball mill and sufficiently pulverized by a wet process to obtain an MZS slurry. Then, this slurry was taken out and filtered, and the cake portion was put in a dryer and sufficiently dried at 150 ° C. to obtain MZS powder.
[0023]
Next, MZS, Al ₂ O ₃ , ST, the first additive component and the second additive component are weighed in the ratios as shown in Tables 1 to 5, and these are put in a ball mill and mixed well in a wet manner. A slurry consisting of a mixture of The slurry was taken out and filtered, and the cake portion was put in a drier and dried sufficiently at 150 ° C. to obtain a powder of the mixture.
[0024]
Next, sample No. For samples Nos. 24 and 88, sample No. 2 at 800 ° C. for 2 hours (800/2). No. 89 was calcined at 900 ° C. for 2 hours (900/2). Here, calcination is performed at 800 ° C. or 900 ° C. for 2 hours, but the temperature can be changed within a range of 700 to 900 ° C. for 2 to 4 hours. Moreover, this calcination was not essential, and those other than these sample Nos were not calcinated.
[0025]
Next, an organic binder is added, granulated, and press-molded to produce a disk-shaped sample having a diameter of about 10 mm and a thickness of about 0.5 mm. The sample is fired at 900 to 950 ° C. for 1 to 4 hours. Then, an Ag paste was applied and fired at 700 ° C. for 15 minutes to form external electrodes, thereby forming a ceramic capacitor.
[0026]
On the other hand, an organic solvent, an organic binder, a plasticizer, and the like are added to the powder of the mixture and mixed to obtain a slurry, and a ceramic green sheet having a thickness of 40 μm is obtained from the slurry using a doctor blade method. An Ag electrode paste was printed in a predetermined pattern, and 11 sheets were alternately laminated and pressure-bonded to prepare a 10-layer laminate, and the obtained laminate was cut to obtain a plurality of chip laminates. Here, as the Ag paste, a paste obtained by slightly mixing additive components for delaying the sintering may be used.
[0027]
Next, this sample was debindered and fired at about 900 to 950 ° C. for 1 to 4 hours. An Ag paste was applied to both ends of the obtained sintered body sample and fired at 700 ° C. for 15 minutes. External electrodes were formed to form a laminated ceramic capacitor (sample size: 1.0 mm × 0.5 mm × 0.5 mm, effective crossing area: 0.05 mm ² , thickness per dielectric layer: 30 μm).
[0028]
[Table 1]

[0029]
[Table 2]

[0030]
[Table 3]

[0031]
[Table 4]

[0032]
[Table 5]

[0033]
Next, C and Q were calculated | required on the conditions of room temperature, HP4284A, 1 MHz, 1V _rms about a disk ceramic capacitor and a laminated ceramic capacitor. The dielectric constant, the insulation resistance at 150 ° C., and the temperature coefficient of the dielectric constant (rate of change of 85 ° C. with respect to 20 ° C.) were obtained as an average of 10 disc-shaped ceramic capacitors. The results were as shown in Tables 6 to 10.
[0034]
In Tables 6 to 10, the numerical value of the insulation resistance ρ, for example, 9.10E + 06 represents 9.10 × 10 ⁶ . The temperature coefficient TCC was calculated using the following equation (1). The leakage current was measured by using a digital multimeter (YOKOGAWA7552) in a 125 ° C. oil and applying a DC of 600 V to the sample.
[0035]
[Expression 1]

[0036]
[Table 6]

[0037]
[Table 7]

[0038]
[Table 8]

[0039]
[Table 9]

[0040]
[Table 10]

[0041]
From the results shown in Tables 6 to 10, the following can be understood. That is, in FIG. 1, the molar ratio [%] of MZS, Al ₂ O ₃ and SrTiO ₃ constituting the main component indicates the composition range of the molar ratio (X, Y, Z) of these three compounds.
A (94.9, 0.1, 5.0)
B (85.0, 10.0, 5.0)
C (65.0, 10.0, 25.0)
D (65.0, 0.1, 34.9)
In the range surrounded by the polygon having the points A to D as vertices, the sample No. 17 to 24, 50 to 52, 78, 79, 83 to 89, a dielectric ceramic composition having desired electrical characteristics can be obtained. 1, 16, 53, 80, 81, a dense sintered body cannot be obtained by firing at 950 ° C. or lower. As shown by 82, the dielectric constant becomes too large as 15 or more, and the temperature coefficient becomes too large on the negative side.
[0042]
Further, the value of a is the sample No. As shown to 56-58, when it exists in the range of 0.10-0.80, the dielectric ceramic composition of a desired electrical property is obtained. 59, when the value of a is less than 0.1, there are many pores in the sintered body, and a dense sintered body cannot be obtained. As shown by 54 and 55, when the value of a is larger than 0.8, a dense sintered body cannot be obtained by firing at 950 ° C.
[0043]
Further, the value of x is the sample No. As shown in 61 and 64, when it is in the range of 0.67 to 1.30, a dielectric ceramic composition having desired electrical characteristics can be obtained, but when the value of x is less than 0.67, sintering is performed. The body is easy to fuse, the appropriate temperature range for firing becomes very narrow, a lot of pores are generated in the sintered body, the Q value is less than 1000, and the sample no. As shown by 62 and 63, when the value of x exceeds 1.3, a dense sintered body cannot be obtained by firing at 950 ° C.
[0044]
In addition, the Nb, Ta or W compound as the first additive component is the sample no. As shown in ₃ , 9, 11, and 14, when it is in the range of 0.01 to 0.2 mol% in terms of NbO _5/2 , TaO _5/2 or WO ₃ , the dielectric of desired electrical characteristics A body porcelain composition is obtained. As shown in FIG. 2, when it is less than 0.01 mol%, the leakage current becomes 1.0 μA or more. As shown in 12, 13 and 15, when it exceeds 0.2 mol%, a dense sintered body cannot be obtained by firing at 950 ° C. The Nb, Ta or W compound may be added alone, or sample no. As shown to 75,77, you may add multiple types simultaneously.
[0045]
In addition, the compound of V, Cr, Mn, Fe, Co, Ni, or Cu as the second additive component is sample no. 3-7, 9, 11, 14, 26-28, 31-33, 36-38, 41-43, 46-48, VO _5/2 , CrO _3/2 , MnO _3/2 , FeO _When it is in the range of 0.05 to 2.0 mol% in terms of _3/2 , CoO _3/2 , NiO or CuO, a dielectric ceramic composition having desired electrical characteristics can be obtained. As shown in 8, 10, 25, 30, 35, 40, and 45, if it is less than 0.05 mol% or exceeds 2.0 mol%, a dense sintered body cannot be obtained. A compound of V, Cr, Mn, Fe, Co, Ni or Cu may be added alone, or sample No. As shown to 66-73, you may add multiple types simultaneously.
[0046]
In addition, although the desired characteristics can be obtained with or without calcination of the mixture composed of MZS, Al ₂ O ₃ and ST, the electrical characteristics change depending on the presence or absence of calcination. In addition, when the calcination causes a reaction between the additive component and the main component or between the additive components, the crystal system changes, and a rapid contraction occurs or the contraction rate increases, the calcination is effective. That is, calcination is effective for suppressing structural defects such as delamination and cracks.
[0047]
Dielectric porcelain compositions according to the present invention, that is, samples evaluated as ○ in Tables 1 to 5, can be sintered by firing at 950 ° C. or less, have a low dielectric constant of 15 or less, and have a high Q value (1 MHz 1000 or more), high resistivity at 150 ° C. (1.0 × 10 ³ MΩcm or more), small temperature coefficient of capacity, JIS standard CG characteristics (−30 to +30 [ppm / ° C.])
CH characteristics (−60 to +60 [ppm / ° C.])
CJ characteristics (−120 to +120 [ppm / ° C.])
PH characteristics (-90 to -210 [ppm / ° C])
RH characteristics (−160 to −280 [ppm / ° C.])
SH characteristics (−270 to −390 [ppm / ° C.])
It turns out that is satisfied.
[0048]
【The invention's effect】
According to the present invention, there is an effect that a low-capacitance (0.01 pF to 30 pF) ceramic capacitor having a high Q value in a high frequency region of several hundred MHz to several GHz and small loss and leakage current can be obtained.
[0049]
Further, according to the present invention, since the sintering temperature of the dielectric ceramic composition can be lowered to 950 ° C. or less, structural defects such as delamination can be suppressed, and the power for firing in the production of the ceramic capacitor. Costs can be reduced and costs can be reduced.
[0050]
In addition, according to the present invention, Ag which is cheaper than Pd can be used as the material of the internal electrode, so that there is an effect that it is possible to reduce the cost of manufacturing the ceramic capacitor.
[Brief description of the drawings]
FIG. 1 is a three-component composition diagram showing a molar ratio [%] of MZS, Al ₂ O ₃ and ST.

Claims

A main component represented by the general formula _{_{_{_{X (Mg a Zn (1-}}}} a)) X SiO X + 2 -YAl 2 O 3 -ZSrTiO 3, Nb, Ta, and selected from W 1 kind or 2 or more elements A first additive component comprising a compound, and a second additive component comprising a compound of one or more elements selected from V, Cr, Mn, Fe, Co, Ni, and Cu,
The molar ratio [%] of magnesium silicate / zinc [(Mg _a Zn _(1-a) ) _X SiO _{X + 2} ], alumina [Al ₂ O ₃ ] and strontium titanate [SrTiO ₃ ] constituting the main components is In the three-component composition diagram showing the molar ratio (X, Y, Z) of the three compounds,
A (94.9, 0.1, 5.0)
B (85.0, 10.0, 5.0)
C (65.0, 10.0, 25.0)
D (65.0, 0.1, 34.9)
In a range surrounded by a polygon having the points A to D as vertices,
The values of a and x in the general formula representing the main component are
0.1 ≦ a ≦ 0.80
0.67 ≦ x ≦ 1.30
In the range of
The first additive component is contained in an amount of 0.01 to 0.2 mol% in terms of NbO _5/2 , TaO _5/2 , or WO ₃ ,
The second additive component is contained in an amount of 0.05 to 2.0 mol% in terms of VO _5/2 , CrO _3/2 , MnO _3/2 , FeO _3/2 , CoO _3/2 , NiO, or CuO. A dielectric ceramic composition characterized by comprising:

A main component represented by the general formula _{_{_{_{X (Mg a Zn (1-}}}} a)) X SiO X + 2 -YAl 2 O 3 -ZSrTiO 3, Nb, Ta, and selected from W 1 kind or 2 or more elements A first additive component comprising a compound, and a second additive component comprising a compound of one or more elements selected from V, Cr, Mn, Fe, Co, Ni, and Cu,
The molar ratio [%] of magnesium silicate / zinc [(Mg _a Zn _(1-a) ) _X SiO _{X + 2} ], alumina [Al ₂ O ₃ ] and strontium titanate [SrTiO ₃ ] constituting the main components is In the three-component composition diagram showing the molar ratio (X, Y, Z) of the three compounds,
A (94.9, 0.1, 5.0)
B (85.0, 10.0, 5.0)
C (65.0, 10.0, 25.0)
D (65.0, 0.1, 34.9)
In a range surrounded by a polygon having the points A to D as vertices,
The values of a and x in the general formula representing the main component are
0.1 ≦ a ≦ 0.80
0.67 ≦ x ≦ 1.30
In the range of
The first additive component is contained in an amount of 0.01 to 0.2 mol% in terms of NbO _5/2 , TaO _5/2 , or WO ₃ ,
The second additive component is contained in an amount of 0.05 to 2.0 mol% in terms of VO _5/2 , CrO _3/2 , MnO _3/2 , FeO _3/2 , CoO _3/2 , NiO, or CuO. Ceramic capacitor using a dielectric ceramic composition as a dielectric layer.

3. The ceramic capacitor according to claim 2, wherein dielectric layers and internal electrodes are alternately laminated.