JP4377482B2 - Dielectric ceramic composition and manufacturing method thereof - Google Patents

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【００５９】
［実施例１］
主成分原料として、ＢａＣＯ₃、Ｎｄ(ＯＨ)₃およびＴｉＯ₂を用いて、仮焼後のＢａＯ、Ｎｄ₂Ｏ₃およびＴｉＯ₂の混合比が下記の表２の主成分組成の欄に示されるものとなるように秤量し、スラリー濃度３０％となるように純水を加え、ボールミルにて１６時間湿式混合し乾燥した。その後、この乾燥した粉末を空気中にて仮焼（１２５０℃、２時間）した。
【００６０】
次に、上記のようにして得た母材粉末に対して、表１に示されるガラス組成物Ａ、ＣｕＯ、Ａｇをそれぞれ下記の表２中の副成分組成の欄に示す割合となるように秤量して添加し、スラリー濃度３３％となるように純水を加え、ボールミルにて２４時間湿式混合し、その後、乾燥した。この乾燥した粉末について、空気中にて再度の仮焼（７５０℃、２時間）を行った。このようにして得た仮焼粉末をスラリー濃度３３％となるように純水を加えボールミルにて２４時間湿式粉砕した後、乾燥して誘電体磁器組成物（試料１〜７）を得た。
【００６１】
次いで、上記のようにして得られた各誘電体磁器組成物１００重量部に対して、バインダーとしてエチルセルロースを６重量部、溶剤としてテルピネオールを９０重量部添加し、らいかい機にて混合後、３本ロールにて分散し、誘電体ペーストを作成した。この誘電体ペーストおよびＡｇペーストをスクリーン印刷法により交互に積層後、４．５ｍｍ×３．２ｍｍのグリーンチップに切断した。このグリーンチップを空気中で２時間焼成（焼成温度は９２０℃とした）した後、端子導体としてＡｇを焼き付けて、図１に示されるような構造をもつチップコンデンサーを作製した。図１において、チップコンデンサーは、Ａｇの内部導体１と誘電体２とが交互に積層され、最外層のＡｇ内部導体１は、それぞれ異なる端子導体３に接続されたものである。
【００６２】
次に、上記の各チップコンデンサーについて、低温燒結性（誘電体２の燒結密度が５．０ｇ／ｃｍ³以上を実用レベルとする）、誘電率ε、Ｑ（＝１／ｔａｎδ）、および、ＴＣＣ（−２５℃から８５℃の誘電率の温度係数）を測定し、結果を下記の表２に示した。尚、表２中の燒結密度の単位は（ｇ／ｃｍ³）、誘電率εおよびＱは無次元、ＴＣＣの単位は（ｐｐｍ／℃）である。
【００６３】
また、試料１と試料５の誘電体磁器組成物を用いて作製したチップコンデンサーに関して、Ａｇ内部導体１まで研磨（図１（Ｂ）に鎖線矢印で示される個所）し、Ａｇ内部導体１からの距離によるＡｇの濃度分布をＥＰＭＡ(Electron Probe Micro Analyzer)によるＷＤＳ(Wavelength Dispersive Spectrometer)により分析し、結果を図２に示した。
【００６４】
【表２】

表２に示されるように、副成分であるＡｇの含有量にかかわらず、低温燒結性、誘電率ε、Ｑ特性、ＴＣＣは、全て実用上問題のないレベルである。しかし、高周波デバイスを設計する際に最も重要な要素である誘電率εに関しては、Ａｇの含有量が増えるにつれて大きくなっている。
【００６５】
ここで、図２に示されるように、Ａｇを含有していない誘電体磁器組成物（試料１）を用いて作製したチップコンデンサーでは、内部導体１からＡｇが誘電体２中に拡散し、内部導体１近傍の誘電体素地中のＡｇ濃度が高く、内部導体１からの距離が大きくなるにしたがって、Ａｇ濃度が減少する濃度分布が存在している。これに対して、Ａｇを所定量含有する本発明の誘電体磁器組成物（試料５）を用いて作製したチップコンデンサーでは、誘電体素地中のＡｇ濃度がほぼ均一であり、内部導体１からのＡｇの拡散が抑制されていることが確認された。そして、上述のように、Ａｇを含有していない誘電体磁器組成物（試料１）を用いて作製したチップコンデンサーでは、誘電体素地中にＡｇの濃度分布を生じているが、これと同時に、誘電率分布も生じている。このため、Ａｇを含有していない誘電体磁器組成物では、設計値通りのデバイス特性を得ることが難しい。しかし、Ａｇを所定量含有する本発明の誘電体磁器組成物を用いて作製したチップコンデンサーでは、内部導体からのＡｇの拡散が抑制され、Ａｇ濃度がほぼ均一となるので、誘電体素地中の誘電特性のバラツキを極めて少ないものとすることができ、所望の設計値通りのデバイス特性が可能となる。
【００６６】
次に、上述のチップコンデンサーと同様の方法により、スクリーン印刷法により導通試験用のグリーンチップを作製し、空気中にて９２０℃で２時間焼成した後、端子導体としてＡｇを焼き付けて、図３に示されるような内部導体１（幅Ｗ＝１００μｍ）と誘電体２と端子導体３とを備えた導通試験用のサンプルを作製した。この導通試験用サンプルの両端の端子導体３間の導通をテスターにて測定し、導通不良率を下記の表３に示した。また、導通試験用サンプルを内部導体１の部位まで研磨し、図４に示されるような内部導体１の端部に生じている空隙の大きさＧを測定して、下記の表３に示した。
【００６７】
【表３】

表３示されるように、内部導体１と誘電体２との間に生じる空隙は、使用する誘電体磁器組成物のＡｇ含有量が増加するにしたがって減少する。このことより、誘電体磁器組成物にＡｇを含有させることで、内部導体からのＡｇの拡散が抑制され、内部導体の端部に発生する空隙を原因とする不具合（内部導体パターン面積の変化、電磁気結合量の変化によるデバイス特性のバラツキ）を低減することができ、設計値通りのデバイス特性を安定して得られることが確認された。また、導通不良率の結果から、Ａｇの含有量が０．３重量％未満（試料１、２）の場合、内部導体１の端子導体３との接続部分において、Ａｇの拡散が原因である内部導体の引き込みが発生し導通不良を生じることが明らかである。しかし、Ａｇを０．３重量％以上含有する場合、内部導体１からのＡｇの拡散が抑制され、これにより、内部導体１の端子導体３との接続部分における引き込みが抑えられ、結果として導通不良が防止される。ただし、Ａｇの含有量が１．５重量％を超える場合（試料７）、コンデンサー特性および導通の両方において問題は生じないが、誘電体素地中のＡｇの取り込み量の限界を超え、極度なＡｇの偏析が生じ、コンデンサーとしての寿命に悪影響を及ぼす。
【００６８】
［実施例２］
主成分原料として、ＢａＣＯ₃、Ｎｄ(ＯＨ)₃およびＴｉＯ₂を用いて、仮焼後のＢａＯ、Ｎｄ₂Ｏ₃およびＴｉＯ₂の混合比が下記の表４の主成分組成の欄に示されるものとなるように秤量し、スラリー濃度３０％となるように純水を加え、ボールミルにて１６時間湿式混合し乾燥した。その後、この乾燥した粉末を空気中にて仮焼（１２５０℃、２時間）した。
【００６９】
次に、上記のようにして得た母材粉末に対して、表１に示されるガラス組成物Ａ、ＣｕＯ、ＡｇＮＯ₃（Ａｇとして換算）をそれぞれ下記の表４中の副成分組成の欄に示す割合となるように秤量して添加し、スラリー濃度３３％となるように純水を加え、ボールミルにて２４時間湿式混合し、その後、乾燥した。この乾燥した粉末について、空気中にて再度の仮焼（７５０℃、２時間）を行った。このようにして得た仮焼粉末をスラリー濃度３３％となるように純水を加えボールミルにて２４時間湿式粉砕した後、乾燥して誘電体磁器組成物（試料８〜１３）を得た。
【００７０】
次いで、上記のようにして得られた各誘電体磁器組成物を用いて、実施例１と同様にして誘電体ペーストを作成した。この誘電体ペーストおよびＡｇペーストを用いて、実施例１と同様にして図１に示されるような構造をもつチップコンデンサー、および、図３に示されるような導通試験用のサンプルを作製した。
【００７１】
次に、上記の各チップコンデンサーについて、実施例1と同様に、低温燒結性（誘電体２の密度が５．０ｇ／ｃｍ³以上を実用レベルとする）、誘電率ε、Ｑ（＝１／ｔａｎδ）、および、ＴＣＣ（−２５℃から８５℃の誘電率の温度係数）を測定し、結果を下記の表４に示した。また、導通試験用のサンプルについて、実施例１と同様に導通不良率を測定し、結果を下記の表５に示した。
【００７２】
【表４】

表４に示されるチップコンデンサーの評価結果より、副成分であるＡｇの含有量にかかわらず、低温燒結性、誘電率ε、Ｑ特性、ＴＣＣは、全て実用上問題のないレベルである。しかし、この場合においても、高周波デバイスを設計する際に最も重要な要素である誘電率εに関しては、Ａｇの含有量が増えるにつれて大きくなっている。そして、Ａｇの含有量が不充分な誘電体磁器組成物（試料８）を用いて作製したチップコンデンサーでは、誘電体素地中に図２に示されるようなＡｇの濃度分布を生じ、これと同時に、誘電率分布も発生している。このことから、Ａｇを含有していない、あるいは、含有量が不充分（０．３重量％未満）な誘電体磁器組成物では、設計値通りのデバイス特性を得ることが難しいことが確認された。
【００７３】
【表５】

表５に示される導通不良率の結果から、副成分であるＡｇの添加形態を変えても、実施例１と同様に、Ａｇの含有量が０．３重量％未満（試料８）の場合、内部導体１の端子導体３との接続部分において、Ａｇの拡散が原因である内部導体の引き込みが発生し導通不良を生じることが明らかである。しかし、Ａｇを０．３重量％以上含有する場合、内部導体１からのＡｇの拡散が抑制され、これにより、内部導体１の端子導体３との接続部分における引き込みが抑えられ、結果として導通不良が防止される。ただし、Ａｇの含有量が１．５重量％を超える（試料１３）場合には、コンデンサー特性および導通の両方において問題は生じないが、誘電体素地中のＡｇの取り込み量の限界を超え、極度なＡｇの偏析が生じ、コンデンサーとしての寿命に悪影響を及ぼす。
【００７４】
上述のように、Ａｇの添加形態をＡｇＮＯ₃に変えた場合にも、Ａｇ粉として添加した場合と同様の効果が奏されることが確認された。
【００７５】
［実施例３］
主成分原料として、ＢａＣＯ₃、Ｎｄ(ＯＨ)₃およびＴｉＯ₂を用いて、仮焼後のＢａＯ、Ｎｄ₂Ｏ₃およびＴｉＯ₂の混合比が下記の表６の主成分組成の欄に示されるものとなるように秤量し、スラリー濃度３０％となるように純水を加え、ボールミルにて１６時間湿式混合し乾燥した。その後、この乾燥した粉末を空気中にて仮焼（１２５０℃、２時間）した。
【００７６】
次に、上記のようにして得た母材粉末に対して、表１に示されるガラス組成物Ａ、ＣｕＯをそれぞれ下記の表６中の副成分組成の欄に示す割合となるように秤量して添加し、スラリー濃度３３％となるように純水を加え、ボールミルにて２４時間湿式混合し、その後、乾燥した。この乾燥した粉末について、空気中にて再度の仮焼（７５０℃、２時間）を行った。このようにして得た仮焼粉末に、母材粉末に対し下記の表６の副成分組成の欄に示す割合となるように秤量したＡｇを添加し、スラリー濃度３３％となるように純水を加えボールミルにて２４時間湿式粉砕した後、乾燥して誘電体磁器組成物（試料１４〜１９）を得た。
【００７７】
次いで、上記のようにして得られた各誘電体磁器組成物を用いて、実施例１と同様にして誘電体ペーストを作成し、この誘電体ペーストおよびＡｇペーストを用い、実施例１と同様にして図１に示されるような構造をもつチップコンデンサー、および、図３に示されるような導通試験用のサンプルを作製した。
【００７８】
次に、上記の各チップコンデンサーについて、実施例1と同様に、低温燒結性（誘電体２の密度が５．０ｇ／ｃｍ³以上を実用レベルとする）、誘電率ε、Ｑ（＝１／ｔａｎδ）、および、ＴＣＣ（−２５℃から８５℃の誘電率の温度係数）を測定し、結果を下記の表６に示した。また、導通試験用のサンプルについて、実施例１と同様に導通不良率を測定し、結果を下記の表７に示した。
【００７９】
【表６】

表６に示されるチップコンデンサーの評価結果より、副成分であるＡｇの含有量にかかわらず、低温燒結性、誘電率ε、Ｑ特性、ＴＣＣは、全て実用上問題のないレベルである。しかし、この場合においても、高周波デバイスを設計する際に最も重要な要素である誘電率εに関しては、Ａｇの含有量が増えるにつれて大きくなっている。そして、Ａｇの含有量が不充分な誘電体磁器組成物（試料１４）を用いて作製したチップコンデンサーでは、誘電体素地中に図２に示すようなＡｇの濃度分布を生じ、これと同時に、誘電率分布も発生しており、Ａｇを含有していない、あるいは、含有量が不充分（０．３重量％未満）な誘電体磁器組成物では、設計値通りのデバイス特性を得ることが難しいことが確認された。
【００８０】
【表７】

表７に示される導通不良率の結果から、副成分であるＡｇの添加時期を変えても、実施例１と同様に、Ａｇの含有量が０．３重量％未満（試料１４）の場合、内部導体１の端子導体３との接続部分において、Ａｇの拡散が原因である内部導体の引き込みが発生し導通不良を生じることが明らかである。しかし、Ａｇを０．３重量％以上含有する場合、内部導体１からのＡｇの拡散が抑制され、これにより、内部導体１の端子導体３との接続部分における引き込みが抑えられ、結果として導通不良が防止される。ただし、Ａｇの含有量が１．５重量％を超える場合（試料１９）には、コンデンサー特性および導通の両方において問題は生じないが、誘電体素地中のＡｇの取り込み量の限界を超え、極度なＡｇの偏析が生じ、コンデンサーとしての寿命に悪影響を及ぼす。
【００８１】
上述のように、Ａｇの添加時期に関しては、２回目の仮焼後の粉砕工程において添加しても、他の副成分と同時に添加する場合（実施例１、２）と同様の効果が奏されることが確認された。
【００８２】
［実施例４］
主成分原料として、ＢａＣＯ₃、Ｎｄ（ＯＨ）₃およびＴｉＯ₂を用いて、仮焼後のＢａＯ、Ｎｄ₂Ｏ₃およびＴｉＯ₂の混合比が下記の表８中の主成分組成の欄に示されるものとなるように秤量し、スラリー濃度３０％となるように純水を加え、ボールミルにて１６時間湿式混合し乾燥した。その後、この乾燥した粉末を空気中にて仮焼（１２５０℃、２時間）した。
【００８３】
次に、上記のようにして得た母材粉末に対して、表１に示されるガラス組成物Ａと、ＣｕＯ、Ａｇを、それぞれ下記の表８の副成分組成の欄に示す割合となるように秤量して添加し、スラリー濃度３３％となるように純水を加え、ボールミルにて２４時間湿式混合し、その後、乾燥した。この乾燥した粉末について、空気中にて再度の仮焼（７５０℃、２時間）を行った。このようにして得た仮焼粉末にスラリー濃度３３％となるように純水を加えボールミルにて２４時間湿式粉砕した後、乾燥して誘電体磁器組成物（試料２０〜３１）を得た。
【００８４】
次いで、上記のようにして得られた各誘電体磁器組成物を用いて、実施例１と同様にして誘電体ペーストを作成し、この誘電体ペーストおよびＡｇペーストを用いて、実施例１と同様にして図１に示されるような構造をもつチップコンデンサーを作製した。ただし、試料２０は焼成温度を１３００℃とした。
【００８５】
次に、上記の各チップコンデンサーについて、実施例1と同様に、低温燒結性（誘電体２の密度が５．０ｇ／ｃｍ³以上を実用レベルとする）、誘電率ε、Ｑ（＝１／ｔａｎδ）、および、ＴＣＣ（−２５℃から８５℃の誘電率の温度係数）を測定し、結果を下記の表８に示した。
【００８６】
【表８】

表８に示されるように、ガラス組成物Ａの含有量が２．０重量％未満、あるいはＣｕＯの含有量が０．１重量％未満である場合（試料２６、２９）、９２０℃での燒結密度が５．０ｇ／ｃｍ³未満となってしまい、所望の低温燒結性が確保できない。一方、ガラス組成物Ａの含有量が１０重量％を超え、あるいはＣｕＯの含有量が３．０重量％を超える場合（試料２８、３１）、Ｑ特性が不充分（１０００未満）となり、実用に供し得ないものである。そして、ガラス組成物Ａの含有量が２．０〜１０重量％の範囲内、ＣｕＯの含有量が０．１〜３．０重量％の範囲内にある試料であっても、ガラス組成物Ａの含有量が３．０〜６．０重量％の範囲で、かつ、ＣｕＯの含有量が０．１〜１．５重量％の範囲内ある場合（試料２２〜２５）は、これを外れる場合（試料２１、２７、３０）に比べて低温焼結性が更に高く、また、Ｑ特性が更に高いものとなっている。
【００８７】
これに対して、本発明の範囲内でガラス組成物Ａ、ＣｕＯおよびＡｇを含有する場合（試料２１〜２４、２７、３０）、９２０℃の焼成温度であっても、燒結密度が目標とする５．０ｇ／ｃｍ³以上となる。また、このときの誘電率ε、Ｑ特性、ＴＣＣは全て実用上問題のないレベルにあり、実用上充分な誘電体磁器を得られることが確認された。
【００８８】
［実施例５］
主成分原料として、ＢａＣＯ₃、Ｎｄ（ＯＨ）₃およびＴｉＯ₂を用いて、仮焼後のＢａＯ、Ｎｄ₂Ｏ₃およびＴｉＯ₂の混合比が下記の表９中の主成分組成の欄に示されるものとなるように秤量し、スラリー濃度３０％となるように純水を加え、ボールミルにて１６時間湿式混合し、乾燥した。次いで、この乾燥した粉末を空気中にて仮焼（１２５０℃、２時間）した。
【００８９】
次に、上記のようにして得た母材粉末に対して、表１に示される各ガラス組成物Ｂ〜Ｌと、ＣｕＯ、Ａｇを、それぞれ下記の表９の副成分組成の欄に示す割合となるように秤量し、スラリー濃度３３％となるように純水を加え、ボールミルにて２４時間湿式混合し、その後、乾燥した。この乾燥した粉末について、空気中にて再度の仮焼（７５０℃、２時間）を行った。このようにして得た仮焼粉末にスラリー濃度３３％となるように純水を加えボールミルにて２４時間湿式粉砕した後、乾燥して誘電体磁器組成物（試料３２〜４２）を得た。
【００９０】
次いで、上記のようにして得られた各誘電体磁器組成物を用いて、実施例１と同様にして誘電体ペーストを作成し、この誘電体ペーストおよびＡｇペーストを用いて、実施例１と同様にして図１に示されるような構造をもつチップコンデンサーを作製した。
【００９１】
次に、上記の各チップコンデンサーについて、実施例1と同様に、低温燒結性（誘電体２の密度が５．０ｇ／ｃｍ³以上を実用レベルとする）、誘電率ε、Ｑ（＝１／ｔａｎδ）、および、ＴＣＣ（−２５℃から８５℃の誘電率の温度係数）を測定し、結果を下記の表９に示した。
【００９２】
【表９】

表９に示されるように、ＳｉＯ₂の含有量が本発明の範囲を超えるガラス組成物Ｉ〜Ｌを含有する場合（試料３９〜４２）、９２０℃での燒結密度が５．０ｇ／ｃｍ³未満となってしまい、所望の低温燒結性が確保できない。また、ＳｉＯ₂の含有量は本発明の範囲内であるが、Ａｌ₂Ｏ₃のような成分（ＳｉＯ₂、Ｂ₂Ｏ₃、ＭｇＯ、ＢａＯ、ＳｒＯ、ＺｎＯおよびＣａＯ以外の成分）の含有量が１０重量％を超えるガラス組成物Ｈを含有する場合（試料３８）も、所望の低温燒結性が確保できない。
【００９３】
これに対して、本発明の範囲内の組成からなるガラス組成物Ｂ〜Ｇと、ＣｕＯおよびＡｇを含有する場合（試料３２〜３７）、９２０℃の焼成温度であっても、燒結密度が目標とする５．０ｇ／ｃｍ³以上となり、このときの誘電率ε、Ｑ特性、ＴＣＣは全て実用上問題のないレベルにあり、実用上充分な誘電体磁器を得られることが確認された。
【００９４】
［実施例６］
主成分原料として、ＢａＣＯ₃、Ｎｄ（ＯＨ）₃およびＴｉＯ₂を用いて、仮焼後のＢａＯ、Ｎｄ₂Ｏ₃およびＴｉＯ₂の混合比が下記の表１０中の主成分組成の欄に示されるものとなるように秤量し、スラリー濃度３０％となるように純水を加え、ボールミルにて１６時間湿式混合し、その後、乾燥した。この乾燥した粉末を空気中にて仮焼（１２５０℃、２時間）した。
【００９５】
次に、上記のようにして得た母材粉末に対して、表１に示されるガラス組成物Ａと、ＣｕＯ、Ａｇを、それぞれ下記の表１０の副成分組成の欄に示す割合となるように秤量して添加し、スラリー濃度３３％となるように純水を加え、ボールミルにて２４時間湿式混合し、その後、乾燥した。この乾燥した粉末について、空気中にて再度の仮焼（７５０℃、２時間）を行った。このようにして得た仮焼粉末にスラリー濃度３３％となるように純水を加えボールミルにて２４時間湿式粉砕した後、乾燥して誘電体磁器組成物（試料４３〜７０）を得た。
【００９６】
次いで、上記のようにして得られた各誘電体磁器組成物を用いて、実施例１と同様にして誘電体ペーストを作成し、この誘電体ペーストおよびＡｇペーストを用いて、実施例１と同様にして図１に示されるような構造をもつチップコンデンサーを作製した。
【００９７】
次に、上記の各チップコンデンサーについて、実施例1と同様に、低温燒結性（誘電体２の密度が５．０ｇ／ｃｍ³以上を実用レベルとする）、誘電率ε、Ｑ（＝１／ｔａｎδ）、および、ＴＣＣ（−２５℃から８５℃の誘電率の温度係数）を測定し、結果を下記の表１０に示した。
【００９８】
【表１０】

表１０に示されるように、主成分であるＢａＯ、Ｎｄ₂Ｏ₃およびＴｉＯ₂の組成が本発明の範囲内にある場合、誘電体磁器組成物は低温燒結性を備え（９２０℃での焼成後の燒結密度が５．０ｇ／ｃｍ³以上）、得られた誘電体磁器の誘電特性は実用上充分であることが確認された。そして、Ｎｄ₂Ｏ₃の割合が減りＢａＯの割合が増すにしたがって、誘電率εが大きくなるとともに、Ｑが減少する傾向がある。また、ＴＣＣはＴｉＯ₂の割合が増すにしたがって、正方向にシフトする傾向がみとめられた。
【００９９】
一方、ＢａＯの含有量が６モル％未満の場合（試料６６、６７）、低温燒結性を確保することができず、誘電率も低下する。ＢａＯ含有量が２３モル％を超える場合（試料６８〜７０）、Ｑ特性が低下（１０００未満）することが確認された。
【０１００】
また、Ｎｄ₂Ｏ₃の含有量が１３モル％未満の場合（試料６８〜７０）、Ｑ特性が低下（１０００未満）し、Ｎｄ₂Ｏ₃含有量が３０モル％を超える場合（試料６６）、低温燒結性を確保することができないことが確認された。
【０１０１】
さらに、ＴｉＯ₂の含有量が６４モル％未満の場合（試料４８、４９、６８）、Ｑ特性が低下（１０００未満）し、ＴｉＯ₂含有量が６８モル％を超える場合（試料４５、４６）、低温燒結性を確保することができないことが確認された。
【０１０２】
上述のように、主成分であるＢａＯ、Ｎｄ₂Ｏ₃およびＴｉＯ₂の組成を本発明の範囲内とすることにより、小さな温度係数を保ったまま、４０から８０以上という広範な誘電率を選択することができ、その所定の誘電率を維持したままＡｇの融点以下での燒結が可能な誘電体磁器組成物を得られることが明らかとなった。
【０１０３】
【発明の効果】
以上詳述したように、本発明によれば所定の組成範囲にあるＢａＯ−Ｎｄ₂Ｏ₃−ＴｉＯ₂系主成分とともに、Ｃｕ酸化物、所定の組成範囲にあるガラス組成物およびＡｇが含有されるので、誘電特性を低下させることなく、ＡｇまたはＡｇを主成分とする合金の融点以下で燒結可能な誘電体磁器組成物が得られる。これにより、低抵抗であるＡｇやＡｇ合金のような融点の低い金属を内部導体として電子部品を構成することが可能となり、結果として高周波用デバイスの諸特性の向上、小型化、低コスト化が可能となる。さらに、副成分として含有されるＡｇが、内部導体から誘電体内へのＡｇ拡散を抑制するので、誘電特性の不均一性が防止され、かつ、内部導体と誘電体間の空隙の発生や、内部導体の外部接続部位における引き込み発生が防止される。また、本発明では、ＰｂＯ、Ｂｉ₂Ｏ₃等の環境汚染物質を含有していないので、近年の環境保護の要請に適応した電子デバイスを提供することが可能になるとともに、その製造工程において廃液処理等の特殊な設備を必要としないため、製造コストの低減が可能となる。さらに、ＰｂＯ、Ｂｉ₂Ｏ₃は高温において蒸発しやすい物質であるが、本発明ではこれらの蒸発性物質を含有しないので、製造工程時の不安定性の除去も可能となる。
【図面の簡単な説明】
【図１】チップコンデンサーの一例を示す図であり、（Ａ）は平面図、（Ｂ）は（Ａ）に示されるチップコンデンサーのＩ−Ｉ線における断面図である。
【図２】実施例１において、チップコンデンサーの誘電体素地中のＡｇの濃度分布を分析した結果を示す図である。
【図３】導通試験用のサンプルの例を示す図であり、（Ａ）は平面図、（Ｂ）は（Ａ）に示されるサンプルのII−II線における断面図である。
【図４】図３（Ａ）に示されるサンプルのIII−III線における拡大断面図である。
【符号の説明】
１…内部導体
２…誘電体
３…端子導体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dielectric ceramic composition, and more particularly to a dielectric ceramic composition having a low temperature sintering property such that Ag or an alloy containing Ag as a main component can be used as an internal conductor, and a method for producing the same.
[0002]
[Prior art]
In recent years, the growth of mobile communication fields such as automobile phones and mobile phones has been remarkable. In these mobile communications, a so-called quasi-microwave high frequency band of several hundred MHz to several GHz is used. For this reason, high-frequency characteristics are emphasized also in electronic devices such as resonators, filters, and capacitors used in mobile communication devices. Further, regarding the spread of mobile communications in recent years, in addition to the improvement of services, miniaturization and cost reduction of communication devices are important factors. Therefore, miniaturization and price reduction are also demanded for the above electronic devices.
[0003]
For example, in the resonator material, the following characteristics (1) to (4) are required at the operating frequency in order to achieve high frequency characteristics and miniaturization.
(1) Large relative dielectric constant: Resonators used in the vicinity of microwaves often use the fact that the wavelength is shortened in proportion to the reciprocal of the square root of the dielectric constant in the dielectric. The length of the vessel can be reduced in proportion to the inverse of the square root of the dielectric constant.
(2) Q is large: In the microwave material, Q defined by Q = 1 / tan δ is used as dielectric loss evaluation, and a large Q indicates a small loss.
(3) Small dielectric constant temperature change: In order to suppress the temperature change of the resonance frequency of a resonator, filter, etc. as much as possible, it is desirable that the dielectric constant temperature change is small.
(4) Able to be sintered at low temperature: In order to realize downsizing of electronic devices, surface mount type components (SMD: Surface Mount Device) with built-in conductor electrodes are becoming mainstream. In order to improve the loss characteristics of the electronic device, it is desirable to use Ag or Cu having a low resistance as the internal conductor electrode. However, Ag and Cu have a low melting point, and the dielectric ceramic composition to be used is required to be sintered at a temperature below these melting points. The problem of this simultaneous sintering is also pointed out when a temperature compensating capacitor material using Ag, Cu or the like as an internal conductor electrode is used.
[0004]
Conventionally, as a dielectric ceramic material for microwaves, BaO-4TiO has been used.₂, BaO-rare earth oxide-TiO₂Composition systems such as systems are well known. In particular, BaO-Nd₂O_Three-TiO₂The system has been extensively studied due to its high dielectric constant and Q value. In recent years, low temperature sintering in this composition system has also been carried out. Patent No. 2613722 (after calcination of main component, pulverized to a predetermined particle size and added with subcomponents); Patent No. 2781500 No. 2781501, No. 2781502, No. 2781503, No. 2778697 (these use glass as an accessory component); JP-A-5-234420, JP-A-6-212564, JP JP-A-6-223625, JP-A-7-69719, JP-A-8-55518, JP-A-8-55519, JP-A-8-167322, JP-A-8-167323, JP-A-8 JP-A-167324, JP-A-8-208328, JP-A-8-208329 (these contain glass as a subcomponent) JP-A-3-290359, JP-A-3-295854, JP-A-3-295855, JP-A-3-295856, JP-A-6-116023, JP-A-6-150719 JP-A-6-162822, JP-A-8-55518, JP-A-8-167322, JP-A-8-167323, JP-A-8-167324, JP-A-8-208328, Japanese Laid-Open Patent Publication No. 8-208329, Japanese Laid-Open Patent Publication No. 8-245262 (these contain Ge oxides as subcomponents); Japanese Laid-Open Patent Publication Nos. 61-56407, 2-44609, No. 5-97508, JP-A-6-1116023, JP-A-8-157257, JP-A-8-277161, etc. There.
[0005]
These are mostly BaO-rare earth oxide-TiO₂As a main component, low-temperature sintering can be achieved by adding a glass composition or a glass composition and several subcomponents thereto. In addition, many of the dielectric materials described above contain PbO, Bi in the main component or additive component.₂O_ThreeEtc. are contained. This is PbO, Bi₂O_ThreeThis is because it has a low-temperature sintering assisting effect as well as a characteristic improvement effect such as an increase in dielectric constant, and by using both of these effects, a low-temperature sintering high-frequency material is made possible.
[0006]
[Problems to be solved by the invention]
As mentioned above, BaO-Nd₂O_Three-TiO₂Since the dielectric ceramics of the system have a high dielectric constant and Q and a low temperature coefficient of dielectric constant, they are used as microwave dielectrics. In particular, in recent years BaO-Nd₂O_Three-TiO₂Low temperature sintering in the system has been realized, but most of them are made of PbO, Bi as described above in order to improve characteristics and assist low temperature sintering.₂O_ThreeAt least one of the above.
[0007]
However, in recent years, the global environmental protection movement has increased. Therefore, in the field of electronic components, PbO, Bi₂O_ThreeReduction of environmental pollutants such as these is desired. In addition, when such an environmental pollutant is contained, special equipment such as a waste liquid treatment facility in the manufacturing process is also required, and it is desirable that no environmental pollutant be contained from the viewpoint of manufacturing cost. Furthermore, PbO, Bi₂O_ThreeAnd the like are easily evaporated at high temperatures, and can easily cause variations in quality during manufacturing. From this point of view, PbO, Bi₂O_ThreeIt is desirable not to include.
[0008]
Further, in the conventional dielectric ceramic composition, when Ag is fired as an inner conductor, Ag of the inner conductor diffuses into the dielectric. The diffusion of Ag is caused by the Ag concentration gradient, so the Ag concentration in the dielectric is not uniform. For example, the Ag concentration is high around the Ag conductor, and the Ag concentration is low at the part away from the Ag conductor. Concentration distribution occurs. In this way, when Ag diffuses into the dielectric, the dielectric characteristics change depending on the concentration thereof. Therefore, electronic parts using Ag as an inner conductor have different dielectric characteristics depending on the part, and desired device characteristics can be obtained. This is a cause of problems such as variations in device characteristics. In addition, the diffusion of Ag into the dielectric body reduces the amount of Ag in the inner conductor, which also prevents desired device characteristics from being obtained and causes variations in device characteristics.
[0009]
Furthermore, when the amount of Ag diffused from the inner conductor into the dielectric is large, a gap is generated between the inner conductor and the dielectric, or the conductor portion for connection to the outside is drawn, resulting in poor conduction. It causes a malfunction. Especially in recent years, miniaturization of high-frequency components has progressed rapidly, and along with this, fine patterning and thinning of the inner conductor are also progressing, so the gap between the inner conductor and the dielectric substrate, Problems caused by pulling in the external connection portions of the internal conductors become a big problem.
[0010]
The present invention has been made in view of such circumstances, and PbO, Bi₂O_ThreeDielectric porcelain composition that can be sintered at low temperature without containing environmental pollutants such as the above, and even if Ag or an Ag alloy is used as an internal conductor, variation in dielectric characteristics due to Ag diffusion is extremely high Provided are a dielectric porcelain composition capable of producing a microwave dielectric porcelain which is small and does not generate an air gap between an inner conductor and a dielectric, and does not generate a pull-in in an outer connecting conductor portion of the inner conductor, and a manufacturing method thereof The purpose is to do.
[0011]
[Means for Solving the Problems]
  In order to achieve such an object, the dielectric ceramic composition of the present invention is composed mainly of the general formula xBaO · yNd.₂O_Three・ ZTiO₂(However, it has a relationship of 6 ≦ x ≦ 23, 13 ≦ y ≦ 30, 64 ≦ z ≦ 68, and x + y + z = 100). .1-1.5% By weight glass composition3.0-6.0The glass composition was contained in a range of 0.3 to 1.5% by weight and the glass composition was in the following composition range.
    5 wt% ≤ SiO₂≦ 15% by weight
    15 wt% ≦ B₂O_Three≦ 25% by weight
    50 wt% ≦ (MgO + BaO + SrO + ZnO + CaO) ≦ 80 wt%
    90 wt% ≦ (SiO₂+ B₂O_Three+ MgO + BaO + SrO + ZnO
                  + CaO) ≦ 100 wt%
[0012]
  The manufacturing method of the dielectric ceramic composition of the present invention includes BaO and Nd.₂O_ThreeAnd TiO₂After mixing the raw materials, calcining is performed at a temperature of 1100 ° C. or higher, and the general formula xBaO · yNd₂O_Three・ ZTiO₂(However, 6 ≦ x ≦ 23, 13 ≦ y ≦ 30, 64 ≦ z ≦ 68, and x + y + z = 100). Cu oxide as a component is 0.1 to 0.1 in terms of CuO1.5% By weight glass composition3.0-6.0The powder in which the weight% and Ag are mixed in the range of 0.3 to 1.5 weight% is calcined again at a temperature lower than the sintering temperature of the powder, and the calcined powder is reduced to a predetermined particle size. And the glass composition is configured to use one having the following composition range.
    5 wt% ≤ SiO₂≦ 15% by weight
    15 wt% ≦ B₂O_Three≦ 25% by weight
    50 wt% ≦ (MgO + BaO + SrO + ZnO + CaO) ≦ 80 wt%
    90 wt% ≦ (SiO₂+ B₂O_Three+ MgO + BaO + SrO + ZnO
                  + CaO) ≦ 100 wt%
[0013]
  In addition, the method for producing the dielectric ceramic composition of the present invention includes BaO, Nd₂O_ThreeAnd TiO₂After mixing the raw materials, the calcination is performed at a temperature of 1100 ° C. or higher, and the general formula xBaO · yNd₂O_Three・ ZTiO₂(However, 6 ≦ x ≦ 23, 13 ≦ y ≦ 30, 64 ≦ z ≦ 68, and x + y + z = 100). Cu oxide as a component is 0.1 to 0.1 in terms of CuO1.5% By weight glass composition3.0-6.0The powder mixed so as to be in the range of% by weight is calcined again at a temperature equal to or lower than the sintering temperature of the powder, and Ag is further added to the calcined powder as a subcomponent from 0.3 to 1 with respect to the base material powder. And a step of pulverizing to a predetermined particle size after adding to a range of 5% by weight, and the glass composition having the following composition range is used.
    5 wt% ≤ SiO₂≦ 15% by weight
    15 wt% ≦ B₂O_Three≦ 25% by weight
    50 wt% ≦ (MgO + BaO + SrO + ZnO + CaO) ≦ 80 wt%
    90 wt% ≦ (SiO₂+ B₂O_Three+ MgO + BaO + SrO + ZnO
                  + CaO) ≦ 100 wt%
[0014]
Furthermore, in the method for producing a dielectric ceramic composition of the present invention, the additive component of Ag is added in the form of metal Ag powder, AgNO._Three, Ag₂The configuration is such that it is at least one of O and AgCl, and the first calcination is performed at a predetermined temperature in the range of 1100 to 1350 ° C.
[0015]
In the present invention, BaO—Nd in a predetermined composition range.₂O_Three-TiO₂The sintering temperature of the dielectric ceramic composition is Ag or the melting point of the alloy containing Ag as a main component while the dielectric properties are substantially maintained by the Cu oxide and glass composition added together with the main component of the system at a predetermined content. In addition, Ag added at a predetermined content as a subsidiary component acts to suppress diffusion of Ag into the dielectric when Ag or an Ag alloy is used as the internal conductor.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described.
[0017]
Dielectric porcelain composition
The dielectric ceramic composition of the present invention has a general formula xBaO · yNd.₂O_Three・ ZTiO₂The Cu component, the glass composition, and Ag are contained as subcomponents with respect to the main component represented by.
[0018]
The main component has a composition in which x, y, and z satisfy the following relationship.
6 ≦ x ≦ 23
13 ≦ y ≦ 30
64 ≦ z ≦ 68
x + y + z = 100
[0019]
Moreover, content of each subcomponent contained with respect to a main component is set within the following range.
Cu oxide: 0.1 to 3.0% by weight in terms of CuO, preferably
0.5-1.5% by weight
Glass composition: 2.0 to 10% by weight, preferably 3.0 to 6.0% by weight
Ag: 0.3 to 1.5% by weight
[0020]
However, said glass composition shall have the composition in the following range.
5 wt% ≤ SiO₂≦ 15% by weight
15 wt% ≦ B₂O_Three≦ 25% by weight
50 wt% ≦ (MgO + BaO + SrO + ZnO
+ CaO) ≦ 80 wt% (preferably ZnO essential)
90 wt% ≦ (SiO₂+ B₂O_Three+ MgO + BaO + SrO + ZnO
+ CaO) ≦ 100 wt%
[0021]
More preferably, the composition range of the glass composition is as follows.
5 wt% ≤ SiO₂≦ 15% by weight
15 wt% ≦ B₂O_Three≦ 25% by weight
50 wt% ≦ ZnO ≦ 80 wt%
90 wt% ≦ (SiO₂+ B₂O_Three+ ZnO) ≦ 100 wt%
[0022]
The composition range of the main component and the content range of the subcomponents as described above are set based on the target dielectric characteristics in the present invention, and will be described below.
[0023]
In the present invention, dielectric properties are evaluated by: (1) low temperature sintering property, (2) relative dielectric constant, (3) temperature coefficient of dielectric constant (hereinafter referred to as TCC), and (4) Q (1 / tan δ) characteristics. Is performed as follows.
[0024]
(1) Low temperature sintering
An object of the present invention is to provide a dielectric ceramic composition capable of being sintered at low temperature, which is used in an electronic device having an internal conductor of Ag or an alloy containing Ag as a main component, and low temperature sintering is the most important characteristic. . Specifically, the sintered body density is 5.0 g / cm after firing at 920 ° C.^ThreeThe above is judged to be practical.
[0025]
(2) Relative permittivity
For example, when the dielectric ceramic composition of the present invention is used for a high frequency dielectric resonator, the length of the resonator depends on the dielectric constant. A higher dielectric constant is advantageous. However, the dielectric ceramic composition of the present invention can be used for various electronic devices having an internal conductor of Ag or an alloy containing Ag as a main component in addition to the above-described dielectric resonator. The value of cannot be determined unconditionally. Therefore, in the present invention, the value of the dielectric constant is not particularly considered.
[0026]
(3) TCC
In the present invention, TCC (ppm / ° C.) is calculated by the following formula.
TCC = [(C_{85 ℃}-C_{-twenty five ℃}) / C_{twenty five ℃}] × (1/110 ° C.) × 10⁶
Where TCC: temperature coefficient of dielectric constant of −25 ° C. to 85 ° C.
C_{85 ℃}   : Capacitance at 85 ℃
C_{-twenty five ℃}  : Capacitance at -25 ° C
C_{twenty five ℃}   : Capacitance at 25 ° C
[0027]
For example, TCC is preferably within ± 30 ppm / ° C for dielectric resonators, TCC is preferably within ± 100 ppm / ° C for dielectric filters, and TCC has a wide range of values for temperature compensation capacitors. If you have it, the area of use will be wider. In order to make the dielectric ceramic composition of the present invention usable for such a dielectric resonator, a dielectric filter, a temperature compensation capacitor, etc., the vicinity of 0 is preferable as a TCC target. A large absolute value is not a problem.
[0028]
(4) Q characteristics
As described above, an object of the present invention is to provide a dielectric ceramic composition capable of being sintered at low temperature, which is used for an electronic device having Ag or an alloy containing Ag as a main component as an internal conductor. Since it means that the loss of the electronic device becomes large, a Q characteristic more than a certain level is required. Therefore, in the present invention, the target of the Q characteristic is set to 1000 or more.
[0029]
Dielectric properties such as (1) low temperature sintering property, (2) relative dielectric constant, (3) TCC, and (4) Q characteristic, which are evaluated as described above, are greatly affected by the main component composition of the dielectric ceramic composition. If affected and the main component composition is out of the composition range of the present invention, the following problems occur.
[0030]
First, when the proportion of BaO is less than 6 mol%, the dielectric constant is lowered and the low-temperature sintering property is also lowered (the sintered density is 5.0 g / cm after firing at 920 ° C.^ThreeLess than). The decrease in the low temperature sintering property is fatal for the purpose of the present invention of providing an electronic device having Ag or an alloy containing Ag as a main component as an inner conductor. Limited amount. On the other hand, when BaO exceeds 23 mol%, the dielectric constant increases and the low-temperature sintering property is improved, TCC is greatly shifted to the negative side, and the Q characteristic is decreased (less than 1000). Decreasing the Q characteristic is not preferable because it causes an increase in the loss of the electronic device. Therefore, the BaO amount is limited to a range in which the Q characteristic can be secured (1000 or more).
[0031]
Next, Nd₂O_ThreeWhen the ratio is less than 13 mol%, the dielectric constant increases and the low-temperature sintering property is improved, but TCC and Q characteristics are deteriorated (less than 1000).₂O_ThreeLimited amount. On the other hand, Nd₂O_ThreeWhen the content exceeds 30 mol%, the dielectric constant decreases and the low-temperature sintering property decreases (the sintered density is 5.0 g / cm after firing at 920 ° C).^ThreeLess).
[0032]
TiO₂When the ratio is less than 64 mol%, TCC increases on the plus side and the Q characteristic deteriorates (less than 1000), which is not preferable. On the other hand, TiO₂When the ratio exceeds 68 mol%, the low-temperature sintering property decreases and TCC increases on the negative side. For this reason, TiO is within the range where low temperature sintering properties can be secured.₂Limited amount.
[0033]
When the subcomponent composition in the dielectric ceramic composition of the present invention is out of the above range, the following problems occur.
[0034]
First, when the ratio of Cu oxide is less than 0.1% by weight in terms of CuO with respect to the main component, the low-temperature sintering effect by Cu oxide becomes insufficient. On the other hand, if it exceeds 3.0% by weight, the Q characteristic is deteriorated (less than 1000), which is not preferable, and the dielectric constant changes nonlinearly with respect to the temperature. .
[0035]
Further, when the glass composition as a subcomponent is less than 2.0% by weight with respect to the main component, the low-temperature sintering effect is insufficient, and when it exceeds 10% by weight, the dielectric constant decreases. At the same time, the Q characteristic also decreases (less than 1000), which is not preferable.
[0036]
For glass compositions, SiO₂And B₂O_ThreeIs an essential component, and a total of 90% by weight or more of a total of the subcomponents selected from MgO, BaO, SrO, ZnO and CaO is preferred, with ZnO being particularly preferred as the subcomponent. For example, Al₂O_ThreeWhen the content of inorganic components other than the above groups such as above exceeds 10% by weight, the low-temperature sintering effect is insufficient, which is not preferable.
[0037]
Furthermore, SiO of the glass composition₂If the amount is less than 5% by weight or B₂O_ThreeIf the amount exceeds 25% by weight, vitrification is difficult and impractical. In addition, SiO₂If the amount exceeds 15% by weight or B₂O_ThreeWhen the amount is less than 15% by weight, the low-temperature sintering effect is insufficient.
[0038]
The reason why the dielectric ceramic composition of the present invention contains Ag as an auxiliary component is to suppress the diffusion of Ag from the inner conductor into the dielectric substrate when Ag or an Ag alloy is used as the inner conductor. is there. When the content of Ag as such a subcomponent is less than 0.3% by weight with respect to the main component, the suppression of Ag diffusion becomes insufficient, and defects due to Ag diffusion, for example, the Ag content in the dielectric body Causes non-uniformity in the dielectric constant, causes a gap between the conductor and the dielectric substrate due to a reduction in the Ag content of the inner conductor, and causes a conduction failure due to the pulling of the inner conductor at the connection portion with the outside. . In addition, the dielectric constant tends to increase as the Ag content increases. However, if the Ag content exceeds 1.5% by weight with respect to the main component, the allowable amount of Ag diffusion in the dielectric is increased. This is undesirable because it causes the segregation of Ag in the dielectric substrate and adversely affects the reliability such as the voltage load life.
[0039]
Method for producing dielectric ceramic composition
Next, the manufacturing method of the dielectric ceramic composition of the present invention will be described.
[0040]
First, oxides of barium, neodymium, and titanium, which are the main components, are prepared, a predetermined amount is weighed and mixed, and calcined. The above mixture is represented by the general formula xBaO · yNd₂O_Three・ ZTiO₂(However, 6 ≦ x ≦ 23, 13 ≦ y ≦ 30, 64 ≦ z ≦ 68, and x + y + z = 100 are satisfied.) The main component material does not need to be an oxide. For example, even when a material that becomes an oxide by heat treatment such as carbonate, hydroxide, sulfide, etc. is used, the oxide is used. A dielectric ceramic composition equivalent to the above can be obtained.
[0041]
The main component raw materials can be mixed by, for example, wet mixing using water or the like, and the mixing time can be set to about 4 to 24 hours. Calcination is performed from a mixture of main component raw materials (BaO-rare earth oxide-TiO 2₂) A step of synthesizing the compound, and it is desirable to carry out at 1100 ° C. or higher, preferably 1100 to 1350 ° C. for about 1 to 24 hours.
[0042]
Next, Cu oxide as a subcomponent, a glass composition having a composition in a predetermined range, and a predetermined amount of Ag are weighed and mixed with the calcined main component (base material powder). That is, Cu oxide as an auxiliary component is 0.1 to 3.0% by weight, preferably 0.5 to 1.5% by weight, and the glass composition is 2.0 to 10% in terms of CuO with respect to the base material powder. It mixes so that it may become the range of weight%, Preferably 3.0-6.0 weight% and Ag 0.3-1.5 weight%. Note that Cu does not need to be an oxide as in the case of the main component material. For example, by using a material that becomes an oxide by heat treatment such as carbonate, hydroxide, sulfide, etc., it is oxidized. It is possible to obtain a dielectric ceramic composition equivalent to the case where a product is used. Further, Ag does not need to be metallic Ag, for example, AgNO._Three, Ag₂By using a material such as O and AgCl that becomes metal Ag by heat treatment, a dielectric ceramic composition equivalent to the case of using metal Ag can be obtained.
[0043]
Moreover, the glass composition to be used shall have the composition in the following range.
5 wt% ≤ SiO₂≦ 15% by weight
15 wt% ≦ B₂O_Three≦ 25% by weight
50 wt% ≦ (MgO + BaO + SrO + ZnO
+ CaO) ≦ 80 wt% (preferably ZnO essential)
90 wt% ≦ (SiO₂+ B₂O_Three+ MgO + BaO + SrO + ZnO
+ CaO) ≦ 100 wt%
[0044]
The more preferable composition range of the glass composition is as follows.
5 wt% ≤ SiO₂≦ 15% by weight
15 wt% ≦ B₂O_Three≦ 25% by weight
50 wt% ≦ ZnO ≦ 80 wt%
90 wt% ≦ (SiO₂+ B₂O_Three+ ZnO) ≦ 100 wt%
[0045]
The above main component and subcomponent can be mixed, for example, by wet mixing using water or the like.
[0046]
Next, the mixed pulverized product is calcined again at a temperature equal to or lower than the sintering temperature, for example, 650 to 850 ° C. for about 1 to 10 hours, and the calcined powder is reduced to a predetermined particle size. Smash. By performing such recalcination, the main component and the subcomponent can be uniformly dispersed, and a powder having a narrow particle size distribution can be obtained. Can be improved.
[0047]
The powder obtained as described above is mixed with an organic binder such as polyvinyl alcohol, acrylic or ethyl cellulose, then molded into a desired shape, and the molded product is fired and sintered. The molding may be dry molding such as press molding as well as wet molding such as a sheet method and a printing method, and the molding method can be appropriately selected according to a desired shape. The firing is desirably performed in, for example, an oxygen atmosphere such as in the air, and the firing temperature can be set within the melting point of Ag or Ag alloy used as the internal conductor, preferably in the range of 850 to 950 ° C. The firing time is preferably about 0.1 to 24 hours.
[0048]
Next, another aspect of the method for producing the dielectric ceramic composition of the present invention will be described.
First, oxides of barium, neodymium, and titanium, which are the main components, are prepared, a predetermined amount is weighed and mixed, and calcined. The above mixture is also represented by the general formula xBaO · yNd₂O_Three・ ZTiO₂(However, 6 ≦ x ≦ 23, 13 ≦ y ≦ 30, 64 ≦ z ≦ 68, and x + y + z = 100 are satisfied.) Moreover, the main component material does not need to be an oxide. For example, even when a material that becomes an oxide by heat treatment such as carbonate, hydroxide, sulfide, etc. is used, the oxide is used. A dielectric ceramic composition equivalent to the above can be obtained.
[0049]
The main component raw materials can be mixed by, for example, wet mixing using water or the like, and the mixing time can be set to about 4 to 24 hours. Calcination is performed from a mixture of main component raw materials (BaO-rare earth oxide-TiO 2₂) A step of synthesizing the compound, and it is desirable to carry out at 1100 ° C. or higher, preferably 1100 to 1350 ° C. for about 1 to 24 hours.
[0050]
Next, a predetermined amount of the Cu oxide as a subcomponent and a glass composition in a predetermined composition range is weighed and mixed with the calcined main component (base material powder). That is, it mixes so that Cu oxide may be 0.1-3.0 weight% in conversion of CuO as a subcomponent with respect to a base material powder, and it may become the range of 2.0-10 weight% of glass compositions. Also in this case, like the main component, Cu does not need to be an oxide, for example, by using a material that becomes an oxide by heat treatment such as carbonate, hydroxide, sulfide, etc. A dielectric ceramic composition equivalent to the case where an oxide is used can be obtained. Moreover, the composition range of the glass composition which can be used is the same as that of the glass composition quoted in the above-mentioned manufacturing method.
[0051]
The above main component and subcomponent can be mixed, for example, by wet mixing using water or the like.
[0052]
Next, the mixed pulverized product is calcined again at a temperature lower than the sintering temperature, for example, 650 to 850 ° C. for about 1 to 10 hours. By performing such recalcination, the main component and the subcomponent can be uniformly dispersed, and a powder having a narrow particle size distribution can be obtained. Can be improved.
[0053]
Next, a predetermined amount of Ag as a subcomponent is weighed and mixed with the calcined powder obtained by the second calcining (Ag is in the range of 0.3 to 1.5% by weight with respect to the base material powder). And the calcined powder is pulverized to a predetermined particle size. As for Ag, it is not necessary to be metallic Ag, for example, AgNO._Three, Ag₂By using a material such as O and AgCl that becomes metal Ag by heat treatment, a dielectric ceramic composition equivalent to the case of using metal Ag can be obtained.
[0054]
The powder obtained as described above is mixed with an organic binder such as polyvinyl alcohol, acrylic or ethyl cellulose, then molded into a desired shape, and the molded product is fired and sintered. The molding may be dry molding such as press molding as well as wet molding such as a sheet method and a printing method, and the molding method can be appropriately selected according to a desired shape. The firing is desirably performed in, for example, an oxygen atmosphere such as in the air, and the firing temperature can be set within the melting point of Ag or Ag alloy used as the internal conductor, preferably in the range of 850 to 950 ° C. The firing time is preferably about 0.1 to 24 hours.
[0055]
The dielectric ceramic composition produced by the production method of the present invention as described above can be sintered at a low temperature below the melting point of Ag or an alloy containing Ag as a main component. For this reason, it becomes possible to constitute an electronic component using a low-resistance metal such as Ag or an Ag alloy having a low melting point as an inner conductor, and further, Ag contained as a subcomponent is transferred from the inner conductor into the dielectric. Since the Ag diffusion is suppressed, nonuniformity of dielectric characteristics is prevented, and the generation of voids between the inner conductor and the dielectric and the pull-in of the inner conductor at the external connection site are prevented. Various characteristics can be improved, downsized, and reduced in cost.
[0056]
In the present invention, PbO, Bi₂O_ThreeBecause it does not contain environmental pollutants such as the above, it is possible to provide electronic devices that meet the recent environmental protection requirements, and it does not require special equipment such as waste liquid treatment, thus reducing manufacturing costs. Is possible. PbO, Bi₂O_ThreeIs a substance that easily evaporates at a high temperature. However, since the present invention does not contain these evaporable substances, a dielectric ceramic composition that is also effective in removing instabilities during the manufacturing process becomes possible.
[0057]
【Example】
Next, an Example is shown and this invention is demonstrated further in detail.
First, 12 types of glass compositions A to L shown in Table 1 below were prepared as glass compositions. Glass compositions A to G are compositions within the scope of the present invention, and glass compositions H to L are comparative examples.
[0058]
[Table 1]

[0059]
[Example 1]
BaCO as the main ingredient_Three, Nd (OH)_ThreeAnd TiO₂BaO, Nd after calcination₂O_ThreeAnd TiO₂The mixture was weighed so that the mixing ratio was as shown in the column of the main component composition in Table 2 below, pure water was added so that the slurry concentration would be 30%, and wet-mixed for 16 hours in a ball mill and dried. Thereafter, the dried powder was calcined in air (1250 ° C., 2 hours).
[0060]
Next, with respect to the base material powder obtained as described above, the glass composition A, CuO, and Ag shown in Table 1 are in proportions shown in the subcomponent composition column of Table 2 below. Weighed and added, pure water was added to a slurry concentration of 33%, wet-mixed in a ball mill for 24 hours, and then dried. The dried powder was re-calcined in the air (750 ° C., 2 hours). The calcined powder thus obtained was added with pure water to a slurry concentration of 33%, wet-ground by a ball mill for 24 hours, and then dried to obtain dielectric ceramic compositions (Samples 1 to 7).
[0061]
Next, 6 parts by weight of ethyl cellulose as a binder and 90 parts by weight of terpineol as a solvent are added to 100 parts by weight of each dielectric ceramic composition obtained as described above. A dielectric paste was prepared by dispersing with this roll. This dielectric paste and Ag paste were alternately laminated by screen printing, and then cut into 4.5 mm × 3.2 mm green chips. This green chip was fired in air for 2 hours (baking temperature was 920 ° C.), and then Ag was baked as a terminal conductor to produce a chip capacitor having a structure as shown in FIG. In FIG. 1, the chip capacitor has Ag inner conductors 1 and dielectrics 2 alternately stacked, and the outermost Ag inner conductor 1 is connected to a different terminal conductor 3.
[0062]
Next, for each of the above-described chip capacitors, low-temperature sintering property (the sintering density of the dielectric 2 is 5.0 g / cm^ThreeThe above are taken as practical levels), dielectric constant ε, Q (= 1 / tan δ), and TCC (temperature coefficient of dielectric constant from −25 ° C. to 85 ° C.) were measured, and the results are shown in Table 2 below. . The unit of the sintering density in Table 2 is (g / cm^Three), Permittivity ε and Q are dimensionless, and the unit of TCC is (ppm / ° C.).
[0063]
Further, with respect to the chip capacitors produced using the dielectric ceramic compositions of Sample 1 and Sample 5, the Ag inner conductor 1 is polished (the part indicated by the chain line arrow in FIG. The concentration distribution of Ag by distance was analyzed by WDS (Wavelength Dispersive Spectrometer) using EPMA (Electron Probe Micro Analyzer), and the results are shown in FIG.
[0064]
[Table 2]

As shown in Table 2, the low-temperature sintering property, the dielectric constant ε, the Q characteristic, and the TCC are all at a level having no practical problem regardless of the content of Ag as a subcomponent. However, the dielectric constant ε, which is the most important factor in designing a high-frequency device, increases as the Ag content increases.
[0065]
Here, as shown in FIG. 2, in the chip capacitor manufactured using the dielectric ceramic composition (sample 1) containing no Ag, Ag diffuses from the inner conductor 1 into the dielectric 2, There is a concentration distribution in which the Ag concentration in the dielectric substrate near the conductor 1 is high and the Ag concentration decreases as the distance from the inner conductor 1 increases. On the other hand, in the chip capacitor produced using the dielectric ceramic composition of the present invention (sample 5) containing a predetermined amount of Ag, the Ag concentration in the dielectric substrate is almost uniform, It was confirmed that Ag diffusion was suppressed. As described above, in the chip capacitor manufactured using the dielectric ceramic composition (sample 1) containing no Ag, the concentration distribution of Ag is generated in the dielectric substrate. At the same time, Dielectric constant distribution also occurs. For this reason, it is difficult to obtain device characteristics as designed with a dielectric ceramic composition that does not contain Ag. However, in the chip capacitor produced using the dielectric ceramic composition of the present invention containing a predetermined amount of Ag, the diffusion of Ag from the inner conductor is suppressed and the Ag concentration becomes substantially uniform. Variations in dielectric characteristics can be made extremely small, and device characteristics as desired can be achieved.
[0066]
Next, a green chip for a continuity test is produced by a screen printing method in the same manner as the above-described chip capacitor. After firing in air at 920 ° C. for 2 hours, Ag is baked as a terminal conductor. The sample for a continuity test provided with the inner conductor 1 (width W = 100 μm), the dielectric 2 and the terminal conductor 3 as shown in FIG. The continuity between the terminal conductors 3 at both ends of this continuity test sample was measured with a tester, and the continuity failure rate is shown in Table 3 below. Further, the sample for continuity test was polished up to the site of the inner conductor 1, and the size G of the gap generated at the end of the inner conductor 1 as shown in FIG. 4 was measured and shown in Table 3 below. .
[0067]
[Table 3]

As shown in Table 3, the gap generated between the inner conductor 1 and the dielectric 2 decreases as the Ag content of the dielectric ceramic composition used increases. From this, by making Ag contained in the dielectric ceramic composition, the diffusion of Ag from the inner conductor is suppressed, and a defect caused by a gap generated at the end of the inner conductor (change in the inner conductor pattern area, It was confirmed that the variation in device characteristics due to changes in the amount of electromagnetic coupling can be reduced, and that device characteristics as designed can be stably obtained. Further, from the result of the continuity failure rate, when the Ag content is less than 0.3% by weight (Samples 1 and 2), the internal conductor 1 is caused by the diffusion of Ag in the connection portion of the internal conductor 1 with the terminal conductor 3. It is clear that conductor pull-in occurs and poor conduction occurs. However, when Ag is contained in an amount of 0.3% by weight or more, the diffusion of Ag from the inner conductor 1 is suppressed, thereby suppressing the pull-in at the connection portion between the inner conductor 1 and the terminal conductor 3, resulting in poor conduction. Is prevented. However, when the Ag content exceeds 1.5% by weight (Sample 7), there is no problem in both the capacitor characteristics and conduction, but the limit of the amount of Ag incorporated in the dielectric substrate exceeds the limit, and extreme Ag Segregation occurs, which adversely affects the life of the capacitor.
[0068]
[Example 2]
BaCO as the main ingredient_Three, Nd (OH)_ThreeAnd TiO₂BaO, Nd after calcination₂O_ThreeAnd TiO₂The mixture was weighed so that the mixing ratio shown in the column of the main component composition in Table 4 below was added, pure water was added so that the slurry concentration became 30%, and wet-mixed for 16 hours in a ball mill and dried. Thereafter, the dried powder was calcined in air (1250 ° C., 2 hours).
[0069]
Next, with respect to the base material powder obtained as described above, the glass composition A, CuO, and AgNO shown in Table 1 were used._Three(Converted as Ag) was weighed and added so as to have the ratio shown in the subcomponent composition column of Table 4 below, pure water was added so that the slurry concentration would be 33%, and wet in a ball mill for 24 hours. Mix and then dry. The dried powder was re-calcined in the air (750 ° C., 2 hours). The calcined powder thus obtained was added with pure water to a slurry concentration of 33%, wet-ground by a ball mill for 24 hours, and then dried to obtain dielectric ceramic compositions (samples 8 to 13).
[0070]
Next, a dielectric paste was prepared in the same manner as in Example 1 using each dielectric ceramic composition obtained as described above. Using this dielectric paste and Ag paste, a chip capacitor having a structure as shown in FIG. 1 and a sample for continuity test as shown in FIG. 3 were produced in the same manner as in Example 1.
[0071]
Next, for each of the above-described chip capacitors, similarly to Example 1, the low temperature sintering property (the density of the dielectric 2 is 5.0 g / cm^ThreeThe above are taken as practical levels), dielectric constant ε, Q (= 1 / tan δ), and TCC (temperature coefficient of dielectric constant from −25 ° C. to 85 ° C.) were measured, and the results are shown in Table 4 below. . Further, the continuity failure rate was measured in the same manner as in Example 1 for the continuity test sample, and the results are shown in Table 5 below.
[0072]
[Table 4]

From the evaluation results of the chip capacitor shown in Table 4, the low-temperature sintering property, the dielectric constant ε, the Q characteristic, and the TCC are all at a level having no practical problem regardless of the content of the subcomponent Ag. However, also in this case, the dielectric constant ε, which is the most important factor in designing a high-frequency device, increases as the Ag content increases. A chip capacitor produced using a dielectric ceramic composition (Sample 8) with insufficient Ag content produces an Ag concentration distribution as shown in FIG. 2 in the dielectric substrate. A dielectric constant distribution is also generated. From this, it was confirmed that it is difficult to obtain device characteristics as designed with a dielectric ceramic composition that does not contain Ag or that is insufficient (less than 0.3% by weight). .
[0073]
[Table 5]

From the result of the conduction failure rate shown in Table 5, even when the addition form of Ag as a subcomponent is changed, as in Example 1, the Ag content is less than 0.3% by weight (Sample 8). It is apparent that the internal conductor 1 is pulled in due to the diffusion of Ag at the connection portion of the internal conductor 1 with the terminal conductor 3, resulting in poor conduction. However, when Ag is contained in an amount of 0.3% by weight or more, the diffusion of Ag from the inner conductor 1 is suppressed, thereby suppressing the pull-in at the connection portion between the inner conductor 1 and the terminal conductor 3, resulting in poor conduction. Is prevented. However, when the Ag content exceeds 1.5% by weight (sample 13), there is no problem in both the capacitor characteristics and conduction, but the limit of the amount of Ag incorporated in the dielectric substrate exceeds the limit. Ag segregation occurs, which adversely affects the lifetime of the capacitor.
[0074]
As described above, the addition form of Ag is AgNO._ThreeIt was confirmed that the same effect as that obtained when Ag powder was added was obtained.
[0075]
[Example 3]
BaCO as the main ingredient_Three, Nd (OH)_ThreeAnd TiO₂BaO, Nd after calcination₂O_ThreeAnd TiO₂The mixture was weighed so that the mixing ratio shown in the column of the main component in Table 6 below was added, pure water was added so that the slurry concentration would be 30%, and wet-mixed for 16 hours in a ball mill and dried. Thereafter, the dried powder was calcined in air (1250 ° C., 2 hours).
[0076]
Next, with respect to the base material powder obtained as described above, the glass composition A and CuO shown in Table 1 are weighed so as to have the proportions shown in the subcomponent composition column of Table 6 below. Pure water was added to a slurry concentration of 33%, wet-mixed with a ball mill for 24 hours, and then dried. The dried powder was re-calcined in the air (750 ° C., 2 hours). To the calcined powder thus obtained, Ag weighed so as to have a ratio shown in the column of subcomponent composition of Table 6 below with respect to the base material powder was added, and pure water was added so that the slurry concentration became 33%. After being wet pulverized for 24 hours in a ball mill, the dielectric ceramic composition (samples 14 to 19) was obtained by drying.
[0077]
Next, using each dielectric ceramic composition obtained as described above, a dielectric paste was prepared in the same manner as in Example 1, and this dielectric paste and Ag paste were used in the same manner as in Example 1. A chip capacitor having a structure as shown in FIG. 1 and a sample for continuity test as shown in FIG. 3 were prepared.
[0078]
Next, for each of the above-described chip capacitors, similarly to Example 1, the low temperature sintering property (the density of the dielectric 2 is 5.0 g / cm^ThreeThe above are taken as practical levels), dielectric constant ε, Q (= 1 / tan δ), and TCC (temperature coefficient of dielectric constant from −25 ° C. to 85 ° C.) were measured, and the results are shown in Table 6 below. . Further, the continuity failure rate of the sample for continuity test was measured in the same manner as in Example 1, and the results are shown in Table 7 below.
[0079]
[Table 6]

From the evaluation results of the chip capacitor shown in Table 6, the low-temperature sintering property, the dielectric constant ε, the Q characteristic, and the TCC are all at a level having no practical problem regardless of the content of the subcomponent Ag. However, also in this case, the dielectric constant ε, which is the most important factor in designing a high-frequency device, increases as the Ag content increases. And in the chip capacitor produced using the dielectric ceramic composition (sample 14) with insufficient Ag content, the concentration distribution of Ag as shown in FIG. 2 is generated in the dielectric substrate. At the same time, Dielectric constant distribution is also generated, and it is difficult to obtain device characteristics as designed with a dielectric ceramic composition that does not contain Ag or has insufficient content (less than 0.3% by weight). It was confirmed.
[0080]
[Table 7]

From the results of the continuity failure rate shown in Table 7, even when the addition time of the subcomponent Ag is changed, the Ag content is less than 0.3% by weight (sample 14) as in Example 1, It is apparent that the internal conductor 1 is pulled in due to the diffusion of Ag at the connection portion of the internal conductor 1 with the terminal conductor 3, resulting in poor conduction. However, when Ag is contained in an amount of 0.3% by weight or more, the diffusion of Ag from the inner conductor 1 is suppressed, thereby suppressing the pull-in at the connection portion between the inner conductor 1 and the terminal conductor 3, resulting in poor conduction. Is prevented. However, when the Ag content exceeds 1.5% by weight (Sample 19), there is no problem in both the capacitor characteristics and conduction, but the limit of the amount of Ag incorporated in the dielectric substrate is exceeded, Ag segregation occurs, which adversely affects the lifetime of the capacitor.
[0081]
As described above, regarding the addition timing of Ag, the same effect as in the case of adding at the same time as other subcomponents (Examples 1 and 2) can be achieved even if added in the pulverization step after the second calcination. It was confirmed that
[0082]
[Example 4]
BaCO as the main ingredient_Three, Nd (OH)_ThreeAnd TiO₂BaO, Nd after calcination₂O_ThreeAnd TiO₂The mixture was weighed so that the mixing ratio was as shown in the column of the main component composition in Table 8 below, pure water was added so that the slurry concentration would be 30%, and wet-mixed for 16 hours in a ball mill and dried. Thereafter, the dried powder was calcined in air (1250 ° C., 2 hours).
[0083]
Next, with respect to the base material powder obtained as described above, the glass composition A, CuO, and Ag shown in Table 1 are in proportions shown in the subcomponent composition column of Table 8 below. The pure water was added to a slurry concentration of 33%, wet-mixed with a ball mill for 24 hours, and then dried. The dried powder was re-calcined in the air (750 ° C., 2 hours). Pure water was added to the calcined powder thus obtained to a slurry concentration of 33%, wet pulverized with a ball mill for 24 hours, and then dried to obtain a dielectric ceramic composition (samples 20 to 31).
[0084]
Next, using each dielectric ceramic composition obtained as described above, a dielectric paste was prepared in the same manner as in Example 1, and this dielectric paste and Ag paste were used as in Example 1. Thus, a chip capacitor having a structure as shown in FIG. 1 was produced. However, the firing temperature of Sample 20 was 1300 ° C.
[0085]
Next, for each of the above-described chip capacitors, similarly to Example 1, the low temperature sintering property (the density of the dielectric 2 is 5.0 g / cm^ThreeThe above are measured as practical levels), dielectric constant ε, Q (= 1 / tan δ), and TCC (temperature coefficient of dielectric constant from −25 ° C. to 85 ° C.) were measured, and the results are shown in Table 8 below. .
[0086]
[Table 8]

  As shown in Table 8, when the content of the glass composition A is less than 2.0% by weight or the content of CuO is less than 0.1% by weight (samples 26 and 29), sintering at 920 ° C. Density is 5.0 g / cm^ThreeThe desired low-temperature sintering property cannot be ensured. On the other hand, when the content of the glass composition A exceeds 10% by weight or the content of CuO exceeds 3.0% by weight (samples 28 and 31), the Q characteristic becomes insufficient (less than 1000), which is practical. It cannot be provided.And even if it is a sample in which the content of the glass composition A is in the range of 2.0 to 10% by weight and the content of CuO is in the range of 0.1 to 3.0% by weight, the glass composition A When the content of Cu is within the range of 3.0 to 6.0% by weight and the content of CuO is within the range of 0.1 to 1.5% by weight (Samples 22 to 25) Compared to (Samples 21, 27, 30), the low-temperature sinterability is higher and the Q characteristic is higher.
[0087]
On the other hand, when the glass composition A, CuO, and Ag are contained within the scope of the present invention (samples 21 to 24, 27, and 30), the sintering density is a target even at a firing temperature of 920 ° C. 5.0 g / cm^ThreeThat's it. In addition, it was confirmed that the dielectric constant ε, Q characteristic, and TCC at this time are all at a level having no practical problem, and that a dielectric ceramic that is practically sufficient can be obtained.
[0088]
[Example 5]
BaCO as the main ingredient_Three, Nd (OH)_ThreeAnd TiO₂BaO, Nd after calcination₂O_ThreeAnd TiO₂Was mixed so that the slurry concentration would be 30%, wet-mixed in a ball mill for 16 hours, and dried. . Next, the dried powder was calcined in air (1250 ° C., 2 hours).
[0089]
Next, with respect to the base material powder obtained as described above, the glass compositions B to L shown in Table 1, CuO, and Ag are shown in the subcomponent composition column of Table 9 below, respectively. Then, pure water was added so that the slurry concentration would be 33%, wet-mixed for 24 hours with a ball mill, and then dried. The dried powder was re-calcined in the air (750 ° C., 2 hours). Pure water was added to the calcined powder thus obtained to a slurry concentration of 33%, wet pulverized with a ball mill for 24 hours, and then dried to obtain dielectric ceramic compositions (samples 32-42).
[0090]
Next, using each dielectric ceramic composition obtained as described above, a dielectric paste was prepared in the same manner as in Example 1, and this dielectric paste and Ag paste were used as in Example 1. Thus, a chip capacitor having a structure as shown in FIG. 1 was produced.
[0091]
Next, for each of the above-described chip capacitors, similarly to Example 1, the low temperature sintering property (the density of the dielectric 2 is 5.0 g / cm^ThreeThe above are taken as practical levels), dielectric constant ε, Q (= 1 / tan δ), and TCC (temperature coefficient of dielectric constant from −25 ° C. to 85 ° C.) were measured, and the results are shown in Table 9 below. .
[0092]
[Table 9]

As shown in Table 9, SiO₂When the glass composition contains the glass compositions I to L exceeding the range of the present invention (samples 39 to 42), the sintered density at 920 ° C. is 5.0 g / cm.^ThreeThe desired low-temperature sintering property cannot be ensured. In addition, SiO₂The content of Al is within the scope of the present invention, but Al₂O_ThreeIngredients (SiO₂, B₂O_Three, MgO, BaO, SrO, ZnO and CaO are contained in the glass composition H containing more than 10% by weight (sample 38), the desired low-temperature sintering property cannot be ensured.
[0093]
In contrast, when glass compositions B to G having a composition within the scope of the present invention, CuO and Ag are included (samples 32 to 37), the sintering density is a target even at a firing temperature of 920 ° C. 5.0 g / cm^ThreeAs described above, it was confirmed that the dielectric constant ε, Q characteristic, and TCC at this time are all at a level having no practical problem, and a dielectric ceramic having sufficient practicality can be obtained.
[0094]
[Example 6]
BaCO as the main ingredient_Three, Nd (OH)_ThreeAnd TiO₂BaO, Nd after calcination₂O_ThreeAnd TiO₂Is mixed so that the slurry concentration becomes 30%, wet-mixed in a ball mill for 16 hours, and then mixed. Dried. The dried powder was calcined in air (1250 ° C., 2 hours).
[0095]
Next, with respect to the base material powder obtained as described above, the glass composition A, CuO, and Ag shown in Table 1 are in proportions shown in the subcomponent composition column of Table 10 below. The pure water was added to a slurry concentration of 33%, wet-mixed with a ball mill for 24 hours, and then dried. The dried powder was re-calcined in the air (750 ° C., 2 hours). Pure water was added to the calcined powder thus obtained to a slurry concentration of 33%, wet pulverized with a ball mill for 24 hours, and then dried to obtain dielectric ceramic compositions (samples 43 to 70).
[0096]
Next, using each dielectric ceramic composition obtained as described above, a dielectric paste was prepared in the same manner as in Example 1, and this dielectric paste and Ag paste were used as in Example 1. Thus, a chip capacitor having a structure as shown in FIG. 1 was produced.
[0097]
Next, for each of the above-described chip capacitors, similarly to Example 1, the low temperature sintering property (the density of the dielectric 2 is 5.0 g / cm^ThreeThe above are taken as practical levels), dielectric constant ε, Q (= 1 / tan δ), and TCC (temperature coefficient of dielectric constant from −25 ° C. to 85 ° C.) were measured, and the results are shown in Table 10 below. .
[0098]
[Table 10]

As shown in Table 10, the main components BaO and Nd₂O_ThreeAnd TiO₂When the composition is within the range of the present invention, the dielectric ceramic composition has a low temperature sintering property (the sintering density after firing at 920 ° C. is 5.0 g / cm^ThreeAs described above, it was confirmed that the obtained dielectric ceramic had practically sufficient dielectric properties. And Nd₂O_ThreeAs the ratio decreases and the ratio of BaO increases, the dielectric constant ε increases and Q tends to decrease. TCC is TiO₂There was a tendency to shift in the positive direction as the percentage increased.
[0099]
On the other hand, when the content of BaO is less than 6 mol% (samples 66 and 67), the low temperature sintering property cannot be ensured, and the dielectric constant also decreases. When the BaO content exceeds 23 mol% (samples 68 to 70), it was confirmed that the Q characteristics were reduced (less than 1000).
[0100]
Nd₂O_ThreeIs less than 13 mol% (samples 68 to 70), the Q characteristics are reduced (less than 1000), and Nd₂O_ThreeWhen the content exceeds 30 mol% (Sample 66), it was confirmed that the low temperature sintering property could not be ensured.
[0101]
In addition, TiO₂Is less than 64 mol% (samples 48, 49, 68), the Q characteristics are reduced (less than 1000), and TiO₂When the content exceeded 68 mol% (samples 45 and 46), it was confirmed that the low temperature sintering property could not be secured.
[0102]
As described above, the main components BaO and Nd₂O_ThreeAnd TiO₂By keeping the composition within the range of the present invention, a wide dielectric constant of 40 to 80 or more can be selected while maintaining a small temperature coefficient, and the melting point of Ag or less can be maintained while maintaining the predetermined dielectric constant. It has been clarified that a dielectric ceramic composition capable of being sintered at a low temperature can be obtained.
[0103]
【The invention's effect】
As described in detail above, according to the present invention, BaO—Nd in a predetermined composition range.₂O_Three-TiO₂Since Cu oxide, glass composition in a predetermined composition range, and Ag are contained together with the system main component, it can be sintered below the melting point of Ag or an alloy containing Ag as a main component without deteriorating the dielectric properties. A dielectric ceramic composition is obtained. As a result, it becomes possible to configure an electronic component using a metal having a low resistance such as Ag or an Ag alloy having a low resistance as an inner conductor, and as a result, various characteristics of the high-frequency device are improved, reduced in size, and reduced in cost. It becomes possible. Furthermore, since Ag contained as a subcomponent suppresses Ag diffusion from the inner conductor into the dielectric, non-uniformity of the dielectric characteristics is prevented, and generation of voids between the inner conductor and the dielectric, Pulling-in at the external connection portion of the conductor is prevented. In the present invention, PbO, Bi₂O_ThreeBecause it does not contain environmental pollutants such as, it becomes possible to provide electronic devices adapted to the recent environmental protection requirements, and no special equipment such as waste liquid treatment is required in the manufacturing process. Manufacturing cost can be reduced. Furthermore, PbO, Bi₂O_ThreeIs a substance that easily evaporates at a high temperature, but in the present invention, since these evaporable substances are not contained, instability during the manufacturing process can be removed.
[Brief description of the drawings]
1A and 1B are diagrams illustrating an example of a chip capacitor, in which FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view taken along line II of the chip capacitor illustrated in FIG.
FIG. 2 is a diagram showing the result of analyzing the concentration distribution of Ag in the dielectric substrate of the chip capacitor in Example 1.
FIG. 3 is a diagram showing an example of a sample for continuity test, (A) is a plan view, and (B) is a cross-sectional view taken along the line II-II of the sample shown in (A).
4 is an enlarged sectional view taken along line III-III of the sample shown in FIG.
[Explanation of symbols]
1 ... Internal conductor
2. Dielectric
3. Terminal conductor

Claims (5)

The main component is represented by the general formula xBaO.yNd ₂ O ₃ .zTiO ₂ (where 6 ≦ x ≦ 23, 13 ≦ y ≦ 30, 64 ≦ z ≦ 68, and x + y + z = 100). As a subsidiary component, Cu oxide is 0.1 to 1.5 % by weight in terms of CuO, glass composition is 3.0 to 6.0 % by weight, and Ag is 0.3 to 1.5 % by weight. And the glass composition is in the following composition range.
5 wt% ≦ SiO ₂ ≦ 15 wt%
15% by weight ≦ B ₂ O ₃ ≦ 25% by weight
50 wt% ≦ (MgO + BaO + SrO + ZnO + CaO) ≦ 80 wt%
90 wt% ≦ (SiO ₂ + B ₂ O ₃ + MgO + BaO + SrO + ZnO
+ CaO) ≦ 100 wt% BaO, Nd ₂ O ₃ and TiO ₂ raw materials are mixed and then calcined at a temperature of 1100 ° C. or higher to obtain a general formula xBaO.yNd ₂ O ₃ .zTiO ₂ (where 6 ≦ x ≦ 23, 13 ≦ y ≦ 30, 64 ≦ z ≦ 68, and x + y + z = 100), and a Cu oxide as a subcomponent with respect to the base material powder in terms of CuO. 1 to 1.5 wt%, the glass composition 3.0 to 6.0 wt%, the mixed powder to be in the range of Ag 0.3 to 1.5 wt%, or less sintering temperature of the powder And calcining the calcined powder again to a predetermined particle size, and the glass composition is in the following composition range: Manufacturing method.
5 wt% ≦ SiO ₂ ≦ 15 wt%
15% by weight ≦ B ₂ O ₃ ≦ 25% by weight
50 wt% ≦ (MgO + BaO + SrO + ZnO + CaO) ≦ 80 wt%
90 wt% ≦ (SiO ₂ + B ₂ O ₃ + MgO + BaO + SrO + ZnO
+ CaO) ≦ 100 wt% BaO, Nd ₂ O ₃ and TiO ₂ raw materials are mixed and then calcined at a temperature of 1100 ° C. or higher to obtain a general formula xBaO.yNd ₂ O ₃ .zTiO ₂ (where 6 ≦ x ≦ 23, 13 ≦ y ≦ 30, 64 ≦ z ≦ 68, and x + y + z = 100), and a Cu oxide as a subcomponent with respect to the base material powder in terms of CuO. A powder prepared by mixing 1 to 1.5 wt% and a glass composition in a range of 3.0 to 6.0 wt% is calcined again at a temperature lower than the sintering temperature of the powder, and the calcined A step of adding Ag as a subcomponent to the powder so as to be in the range of 0.3 to 1.5% by weight with respect to the base material powder, and then pulverizing to a predetermined particle size. A method for producing a dielectric ceramic composition, wherein the product is in the following composition range.
5 wt% ≦ SiO ₂ ≦ 15 wt%
15% by weight ≦ B ₂ O ₃ ≦ 25% by weight
50 wt% ≦ (MgO + BaO + SrO + ZnO + CaO) ≦ 80 wt%
90 wt% ≦ (SiO ₂ + B ₂ O ₃ + MgO + BaO + SrO + ZnO
+ CaO) ≦ 100 wt% The method for producing a dielectric ceramic composition according to claim 2 or ₃ , wherein the auxiliary component Ag is added in at least one of metallic Ag powder, AgNO ₃ , Ag ₂ O, and AgCl.   5. The method for producing a dielectric ceramic composition according to claim 2, wherein the first calcination is performed at a predetermined temperature within a range of 1100 to 1350 ° C. 6.

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