JP4349007B2 - Multilayer electronic components - Google Patents

Description

この表１から明らかなように、試料番号１は、平均粒径０．３μｍのＢａ_0.95Ｃａ_0.05ＴｉＯ_３が得られたものの、昇温速度が５℃／minと遅いため、ＢａＣＯ_３やＣａＴｉＯ_３等の異相の生成が認められた。
【００７１】
これに対し試料番号２は、昇温速度が３０℃／minと速く、したがって仮焼処理時間も短くて済むため、平均粒径が０．３μｍのＢａ_0.95Ｃａ_0.05ＴｉＯ_３からなる単一相が得られた。
【００７２】
また、試料番号３は、仮焼最高温度を１１００℃と高くしたことにより、Ｂａ_0.95Ｃａ_0.05ＴｉＯ_３の単一相が得られ、異相の生成は認められなかったが、昇温速度が５℃／minと遅く、仮焼最高温度を高くしたことにより仮焼処理時間も長くなり、解砕後の平均粒径が０．４μｍと粗くなった。
【００７３】
（実施例Ｂ）
セラミック素原料として、ＢａＣＯ_３、ＴｉＯ_２、ＺｒＯ_２の各粉末を用意し、モル比でＢａＣＯ_３：ＴｉＯ_２：ＺｒＯ_２：＝１．００：０．８０：０．２０となるように秤量した。
【００７４】
次に、実施例Ａと同様の方法・手順で湿式粉砕した後、蒸発乾燥させて混合粉末を得、さらに、実施例Ａと同様、３種類の仮焼プロファイルで仮焼処理を実行し、その後乾式粉砕機で仮焼粉末を解砕し、試料番号４〜６の複合酸化物粉末を作製した。
【００７５】
次いで、各試料についてＳＥＭで観察して平均粒径を測定し、ＸＲＤで構成相を確認した。
【００７６】
表２は仮焼条件と測定結果を示している。
【００７７】
【表２】

この表２から明らかなように、試料番号４は、平均粒径０．３μｍのＢａＴｉ_0.80Ｚｒ_0.20Ｏ_３が得られたものの、昇温速度が５℃／minと遅いため、ＢＡＺｒＯ_３等の異相の生成が認められた。
【００７８】
これに対し試料番号５は、昇温速度が３０℃／minと速く、したがって仮焼処理時間も短くて済み、平均粒径が０．３μｍのＢａＴｉ_0.80Ｚｒ_0.20Ｏ_３からなる単一相が得られた。
【００７９】
また、試料番号６は、仮焼最高温度を１１００℃と高くしたことにより、ＢａＴｉ_0.80Ｚｒ_0.20Ｏ_３の単一相が得られ、異相の生成は認められなかったが、昇温速度が５℃／minと遅く、仮焼最高温度を高くしたことにより仮焼処理時間も長くなり、解砕後の平均粒径が０．５μｍと粗くなった。
【００８０】
（実施例Ｃ）
セラミック素原料として、ＣａＣＯ_３、ＴｉＯ_２、ＺｒＯ_２の各粉末を用意し、モル比でＣａＣＯ_３：ＴｉＯ_２：ＺｒＯ_２：＝１．００：０．６５：０．３５となるように秤量した。
【００８１】
次に、実施例Ａと同様の方法・手順で湿式粉砕した後、蒸発乾燥させて混合粉末を得、さらに、実施例Ａと同様、３種類の仮焼プロファイルで仮焼処理を行ない、その後乾式粉砕機で仮焼粉末を解砕し、試料番号７〜９の複合酸化物粉末を作製した。
【００８２】
次いで、各試料についてＳＥＭで観察して平均粒径を測定し、ＸＲＤで構成相を確認した。
【００８３】
表３は仮焼条件と測定結果を示している。
【００８４】
【表３】

この表３から明らかなように、試料番号７は、平均粒径０．３μｍのＣａＴｉ_0.65Ｚｒ_0.35Ｏ_３が得られたものの、昇温速度が５℃／minと遅いため、ＣａＴｉＯ_３等の異相の生成が認められた。
【００８５】
これに対し試料番号８は、昇温速度が３０℃／minと速く、したがって仮焼処理時間も短くて済み、平均粒径が０．３μｍのＣａＴｉ_0.65Ｚｒ_0.35Ｏ_３からなる単一相が得られた。
【００８６】
また、試料番号９は、仮焼最高温度を１１００℃と高くしたことにより、ＣａＴｉ_0.65Ｚｒ_0.35Ｏ_３の単一相が得られ、異相の生成は認められなかったが、昇温速度が５℃／minと遅く、仮焼最高温度を高くしたことにより仮焼処理時間も長くなり、解砕後の平均粒径が０．５μｍと粗くなった。
【００８７】
すなわち、実施例Ａ〜Ｃから明らかなように、反応開始温度（４００℃）から仮焼最高温度（１０００℃〜１１００℃）に到達するまでの時間、昇温速度を５℃／minに設定して仮焼炉を昇温させた場合は、仮焼処理時間が長いため、異相が生成されるか、又は粒径が粗くなったのに対し、昇温速度を３０℃／minに設定して仮焼炉を昇温させた場合は、仮焼処理時間が短いため、より微粒で異相が生成されることのない高純度の複合酸化物粉末を得ることができることが分った。
【００８８】
〔第２の実施例〕
セラミック素原料としてＢａＣＯ_３、ＣａＣＯ_３、ＴｉＯ_２の各粉末を用意し、組成式（Ｂａ_0.946Ｃａ_0.060）ＴｉＯ_３の複合酸化物粉末が得られるように各粉末を秤量し、第１の実施例と同様の方法・手順で混合粉末を得た。
【００８９】
次に、この混合粉末を仮焼炉に入れ、異なる３種類の仮焼プロファイルで仮焼処理を施し、複合酸化物粉末を作製した。
【００９０】
すなわち、まず、炉内温度が４００℃から１０００℃に到達するまで、５℃／minの昇温速度で仮焼炉を昇温させ、その後、温度１０００℃で２時間保持した後、降温させることによって仮焼物を得、この後乾式粉砕機で仮焼物を解砕し、試料番号１１の複合酸化物粉末を作製した。
【００９１】
また、炉内温度が４００℃から１０５０℃に到達するまで、１０℃／minの昇温速度で仮焼炉を昇温させ、その後、温度１０５０℃で１時間保持した後、降温させることによって仮焼物を得、この後乾式粉砕機で仮焼物を解砕し、試料番号１２の複合酸化物粉末を作製した。
【００９２】
また、炉内温度が４００℃から１１００℃に到達するまで、３０℃／minの昇温速度で仮焼炉を昇温させ、その後、温度１１００℃で３０分間保持した後降温させることによって仮焼物を得し、この後乾式粉砕機で仮焼物を解砕し、試料番号１３の複合酸化物粉末を作製した。
【００９３】
次に、セラミック素原料として、ＢａＣＯ_３、ＣａＣＯ_３、及びＴｉＯ_２の各粉末に加え、Ｄｙ_２Ｏ_３粉末を用意し、組成式（Ｂａ_0.926Ｃａ_0.060Ｄｙ_0.020）ＴｉＯ_３の複合酸化物粉末が得られるように各粉末を秤量し、上述と同様にして混合粉末を得た。
【００９４】
次に、この混合粉末を仮焼炉に入れ、異なる２種類の仮焼プロファイルで仮焼処理を施し、複合酸化物粉末を作製した。
【００９５】
すなわち、まず、炉内温度が４００℃から１０００℃に到達するまで、５℃／minの昇温速度で仮焼炉を昇温させ、その後、温度１０００℃で２時間保持した後、降温させることによって仮焼物を得、この後乾式粉砕機で仮焼物を解砕し、試料番号１４の複合酸化物粉末を作製した。
【００９６】
また、炉内温度が４００℃から１１００℃に到達するまで、３０℃／minの昇温速度で仮焼炉を昇温させ、その後、温度１１００℃で３０分間保持した後、降温させることによって仮焼物を得、この後乾式粉砕機で仮焼物を解砕し、試料番号１５の複合酸化物粉末を作製した。
【００９７】
次に、試料番号１１〜１５について、ＳＥＭ観察により平均粒径を測定し、さらにＸＲＤで回折パターンを求め、リートベルト解析を行って結晶構造を解析し、結晶軸の軸比ｃ／ａを算出した。
【００９８】
表４は各試料の組成成分、仮焼条件、平均粒径、及び軸比ｃ／ａを示している。
【００９９】
【表４】

各試料共、平均粒径は０．３０μｍであった。
【０１００】
試料番号１１は、昇温速度が５℃／minと遅いため、仮焼処理に長時間を要し、このため軸比ｃ／ａが１．００８と小さく、正方晶性が低いことが分かった。これは、仮焼処理時間が長いため、ＢａＴｉＯ_３の規則正しい原子配列に、異元素であるＣａが固溶し、その結果、原子配列に乱れが生じ、軸比ｃ／aが小さくなったと考えられる。
【０１０１】
また、試料番号１２は、昇温速度を１０℃／minと上昇させてはいるものの、昇温速度は未だ不十分であり、このため軸比ｃ／ａが１．００８と小さく、正方晶性が低いことが分かった。
【０１０２】
これに対して試料番号１３は、昇温速度を３０℃／minに上げて仮焼合成反応を生じさせているので、平均粒径の粗大化を招くことなく、軸比ｃ／aを１．００９と大きくすることができ、正方晶性を向上させることのできることが分った。
【０１０３】
さらに、試料番号１４は、試料番号１１と同様、昇温速度が５℃／minと遅いため、仮焼処理に長時間を要し、このため軸比ｃ／ａが１．００８と小さく、正方晶性が低くなることが分かった。
【０１０４】
これに対し試料番号１５は、試料番号１３と同様、昇温速度を３０℃／minに上げて仮焼合成反応を生じさせているので、平均粒径の粗大化を招くことなく、軸比ｃ／aを１．００９と大きくすることができ、正方晶性を向上させることのできることが分った。
【０１０５】
〔第３の実施例〕
昇温速度３０〜６０℃／ｍｉｎ、仮焼最高温度１０５０〜１１００℃、保持時間０．５ｈｒの仮焼条件でＣａ変性チタン酸バリウム（Ｂａ_ｘＣａ_ｙ）ＴｉＯ_３からなる試料番号２１〜２６の複合酸化物粉末を作製した。
【０１０６】
なお、本第３の実施例では、ｙ値を一定とし、Ａサイト元素である（Ｂａ，Ｃａ）とＢサイト元素であるＴｉとのモル比ｍを０．９９１〜１．００６の間で異なるように、Ｂａ／Ｔｉを変えている。
【０１０７】
また、比較例として、試料番号２３と同一組成成分の混合粉末について、試料番号１１、１２と同様の仮焼条件で仮焼処理を施し、試料番号２７、２８の複合酸化物粉末を作製した。
【０１０８】
次に、各試料について第２の実施例と同様、平均粒径を測定し、また結晶軸の軸比ｃ／ａを算出した。
【０１０９】
表５は各試料の組成成分、仮焼条件、平均粒径、及び軸比ｃ／ａを示している。
【０１１０】
【表５】

表５から明らかなように、試料番号２１〜２６は昇温速度を３０℃〜６０℃／minに設定して高速昇温を行っているため、軸比ｃ／ａはいずれも１．００９と高い正方晶性を得ているが、さらにモル比ｍが０．９９２≦ｍ≦１．００５に調製された試料番号２２〜２４、２７は、平均粒径が０．２５μｍとなり、試料番号２１及び２５に比べてさらに微粒化しており、したがって高正方晶性を維持しつつより一層の微粒化を図る観点からは、モル比ｍが０．９９２≦ｍ≦１．００５が好ましいことが分った。
【０１１１】
また、試料番号２７、２８は昇温速度がそれぞれ５℃／min、１０℃／minと遅いため、仮焼処理に長時間を要し、このため軸比ｃ／ａが１．００８となり正方晶性が低下することが分った。
【０１１２】
尚、本発明者らが、別途実験を行ったところ、ＣａのＴｉに対するモル比ｘが０．２１の場合、及びＤｙのＴｉに対するモル比ｙが０．０７の場合は、いずれもＴｉに対するＣａやＤｙの含有量が過剰となり、昇温速度を３０℃／minに上げて仮焼処理を行なってもＣａＴｉＯ_３等の異相の生成が確認された。
【０１１３】
〔第４の実施例〕
まず、ＢａＣＯ_３、ＣａＣＯ_３、ＴｉＯ_２の各粉末を（Ｂａ_0.938Ｃａ_0.060）ＴｉＯ_３が得られるように秤量し混合した。
【０１１４】
次いで、炉内圧を大気圧（１．０１×１０^５Ｐａ）に設定し、炉内温度が４００℃から９５０℃に到達するまで、５℃／minの昇温速度で仮焼炉を昇温させ、その後、温度９５０℃で３０分間保持した後、降温させることによって仮焼物を得、この後乾式粉砕機で仮焼物を解砕し、試料番号３１の複合酸化物粉末を作製した。
【０１１５】
また、炉内圧を７．９８×１０^４Ｐａに減圧し、試料番号３１と同様の仮焼条件で仮焼処理を行なって仮焼物を得、その後乾式粉砕機で仮焼物を解砕し、試料番号３２の複合酸化物粉末を作製した。
【０１１６】
また、炉内圧を大気圧（１．０１×１０^５Ｐａ）に設定し、炉内温度が４００℃から１０５０℃に到達するまで、３０℃／minの昇温速度で仮焼炉を昇温させ、その後、温度１０５０℃で３０分間保持した後、降温させることによって仮焼物を得、この後乾式粉砕機で仮焼物を解砕し、試料番号３３の複合酸化物粉末を作製した。
【０１１７】
また、炉内圧を７．９８×１０^４Ｐａに減圧し、試料番号３３と同様の仮焼条件で仮焼処理を行なって仮焼物を得、その後乾式粉砕機で仮焼物を解砕し、試料番号３４の複合酸化物粉末を作製した。
【０１１８】
次に、各試料について第２の実施例と同様、平均粒径を測定し、また結晶軸の軸比ｃ／ａを算出した。
【０１１９】
表６は各試料の組成成分、仮焼条件、平均粒径、及び軸比ｃ／ａを示している。
【０１２０】
【表６】

試料番号３１は、大気圧下、昇温速度が５℃／minで仮焼処理を行なっているため、平均粒径は０．２５μｍと微粒ではあるが、軸比ｃ／aが１．００７と小さく、正方晶性が低下することが分った。
【０１２１】
また、試料番号３２は仮焼炉の炉内圧を７．９８×１０^４Ｐａに減圧させることにより、軸比ｃ／ａは１．００８と向上するが、未だ正方晶性が不十分である。
【０１２２】
これに対して試料番号３３は、仮焼炉の炉内圧は大気圧であるが昇温速度を３０℃／minにしているため、軸比ｃ／ａは１．００９と大きくなって高い正方晶性を得ることができる。
【０１２３】
さらに、試料番号３４では、仮焼炉の炉内圧を７．９８×１０^４Ｐａに減圧しているため、軸比ｃ／ａも１．００９と高正方晶性を維持しながら平均粒径も０．２０μｍと更に微粒化しており、したがって、炉内圧を減圧することにより、より一層微粒で正方晶性の高い複合酸化物粉末を得ることのできることが分った。
【０１２４】
〔第５の実施例〕
この第５の実施例では、複合酸化物粉末を使用して積層セラミックコンデンサを作製し、特性を評価した。
すなわち、まず、試料番号１１（第２の実施例、表４）と試料番号１３（第２の実施例、表４）の複合酸化物粉末、及び試料番号２３（第３の実施例、表５）と試料番号３４（第４の実施例、表６）の複合酸化物粉末を用意した。
【０１２５】
次いで、これら複合酸化物粉末１００重量部に対し、Ｙ_２Ｏ_３を１．８６重量部、ＭｇＯを０．３３６重量部、ＢａＣＯ_３を１．２８重量部、ＳｉＯ_２を０．７４重量部、ＭｎＯ_２を０．３２７重量部、及びＢ_２Ｏ_３を０．３１２重量部添加し、さらにポリビニルブチラール系バインダ及びエタノール等の有機溶媒を加えてボールミルにより湿式混合し、セラミックスラリーを作製した。
【０１２６】
次に、このセラミックスラリーをドクターブレード法により、成形加工を施し、セラミックグリーンシートを作製した。
【０１２７】
次に、上記セラミックグリーンシート上にＮｉを主成分とする内部電極用導電性ペーストをスクリーン印刷し、内部電極層を形成し、さらに、内部電極層が形成されたセラミックグリーンシートを、内部電極層の引出部が互い違いとなるように複数枚積層し、積層体を作製した。
【０１２８】
そして、この積層体をＮ_２雰囲気中にて３５０℃の温度に加熱し、バインダを分解させて脱バインダ処理を行なった後、酸素分圧１０^−９〜１０^−１２ＭＰａのＨ_２−Ｎ_２−Ｈ_２Ｏガスからなる還元性雰囲気下、１３００℃で２時間焼成し、セラミック焼結体を得た。
【０１２９】
次いで、Ｂ_２Ｏ_３−Ｌｉ_２Ｏ−ＳｉＯ_２−ＢａＯ系ガラス材を含有したＡｇを主成分とする外部電極用導電性ペーストを用意し、該外部電極用導電性ペーストをセラミック焼結体の両端面に塗布し、Ｎ_２雰囲気下、温度６００℃で焼付処理を行ない、これにより外部電極を形成し、試料番号１１′、１３′、２３′３４′の積層セラミックコンデンサを作製した。
【０１３０】
尚、作製された積層セラミックコンデンサの外形寸法は縦１．６ｍｍ、横３．２ｍｍ、厚み１．２ｍｍであった。また、積層セラミックコンデンサの誘電体層の厚みは、５μｍであり、有効誘電体層の層数は１００層であった。また、一層当たりの対向電極面積は２．１ｍｍ^２であった。
【０１３１】
次に、上記各試料について、室温での誘電率、誘電損失、温度変化に対する静電容量の変化率（以下、「容量変化率」という）及び高温負荷寿命試験を行なった。
【０１３２】
ここで、誘電率及び誘電損失は自動ブリッジ式測定器で測定した、
また、容量変化率は、２５℃での静電容量を基準値とし、１２５℃における静電容量の変化率を測定した。
【０１３３】
さらに、高温負荷寿命試験は、温度１５０℃、電界強度１５ＫＶ／ｍｍとなるように印加電圧を調整し、絶縁抵抗の経時変化を測定することにより行った。すなわち、各試料を３０個ずつサンプリングし、絶縁抵抗が２００ｋΩ以下になったときの時間を試料の寿命と判断し、その平均時間を算出し、高温負荷寿命を評価した。
【０１３４】
表７はその測定結果を示している。
【０１３５】
【表７】

試料番号１１′は、軸比ｃ／ａが１．００８と小さく（表４参照）、したがって正方晶性が低いので、Ｙ_２Ｏ_３やＭｇＯ等の添加物が複合酸化物粉末に過度に固溶し、したがって比誘電率は２７５０と高いが、誘電損失は４．６％と大きく、また容量変化率も−１６．８％と大きい。すなわち、ＥＩＡ（米国電子工業会）の規格によると、高誘電率系の積層セラミックコンデンサでは、２５℃を基準に−５５〜１２５℃での容量変化率が±１５％以内であることが必要とされているが（Ｘ７Ｒ特性）、試料番号１１′では−１５％を超えて温度特性が悪化し、Ｘ７Ｒ特性を満たさないことが分った。しかも、高温負荷時の平均寿命も１７．６時間と短く、高温負荷時の耐久性にも欠ける。
【０１３６】
これに対して試料番号１３′、２３′及び３４′は、いずれも軸比ｃ／ａが１．００９であり（表４、表５、表６参照）、正方晶性が高いので、Ｙ_２Ｏ_３やＭｇＯ等の添加物の複合酸化物粉末への固溶が適度に抑制され、したがって容量変化率も−１２．５〜−１２．８％であり、−１５％以内に抑えることができる。しかも、比誘電率や誘電損失、高温負荷時の耐久性も満足できるものである。
【０１３７】
尚、試料番号１３′、２３′及び３４′は、良好な静電容量の温度特性を確保することができ、比誘電率や誘電損失、高温負荷時の耐久性も良好であるが、試料番号１３′の平均粒径は０．３０μｍであり（表４参照）、試料番号２３′の平均粒径は０．２５μｍであり（表５参照）、試料番号３４′の平均粒径は０．２０μｍであり（表６参照）、平均粒径が細かくなるに伴い、誘電損失や小さくなり、また、高温負荷時の平均寿命も長くなっている。
【０１３８】
すなわち、試料番号１３′、２３′及び３４′から、平均粒径が微粒化すればする程、誘電損失が低下すると共に高温負荷時の耐久性が向上し、信頼性の優れた積層セラミックコンデンサを得ることができることが確認された。
【０１３９】
【発明の効果】
以上詳述したように本発明に係る積層型電子部品は、誘電体磁器組成物からなる磁器内に内部電極が埋設されると共に、該磁器の表面に外部電極が形成された積層型電子部品において、前記磁器は、一般式ＡＢＯ _３ で表されるペロブスカイト型構造の複合酸化物を主成分とすると共に、副成分としてマグネシウム酸化物、マンガン酸化物、及びケイ素酸化物のうちの少なくとも１種を含有し、かつ、焼成前の前記複合酸化物は、セラミック素原料を混合して得られた混合粉末を、合成反応を開始する反応開始温度から仮焼最高温度に到達するまでの間、昇温速度を３０℃／分以上に設定して仮焼した合成物であるので、仮焼時間が短時間で済み、異相が生成されることもなく、微粒で正方晶性の高い高純度な複合酸化物粉末を製造することができる。そして、これにより高比誘電率を有し、薄層化しても温度変化に対する静電容量の容量変化率も小さく、誘電損失や高温負荷時の耐久性等、各種特性が良好な信頼性に優れた積層セラミックコンデンサ等の積層型電子部品を得ることができる。
【０１４０】
また、前記ペロブスカイト型構造のＡサイト元素はＢａ及びＣａのうちの少なくとも１種を含み、Ｂサイト元素はＴｉ及びＺｒのうちの少なくとも１種を含み、さらに前記Ａサイト元素と前記Ｂサイト元素とは、総計が３種以上の元素で構成されている場合に、上記効果を容易に奏することができる。
【０１４１】
また、前記焼成前の前記複合酸化物は、一般式（Ｂａ_1-x-yＣａ_ｘＲｅ_ｙＯ）_ｍＴｉＯ_２（ただし、ＲｅはＹ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、及びＹｂの中から選択された少なくとも１種であり、０．９９２≦ｍ≦１．００５、０＜ｘ≦０．２０、０≦ｙ≦０．０６）であるので、微粒領域で高比誘電率を有する積層セラミックコンデンサ等の積層型電子部品を得ることができる。
【０１４２】
また、前記仮焼が、減圧雰囲気下、例えば７．９８×１０^４Ｐａ以下で行うことにより、高い正方晶性を維持しつつ、より一層微粒化された複合酸化物粉末を得ることができる。
【図面の簡単な説明】
【図１】本発明に係る複合酸化物粉末の製造方法の一実施の形態を示す製造工程図である。
【図２】仮焼工程における仮焼プロファイルを示す図である。
【図３】上記複合酸化物粉末を使用して製造された積層型電子部品としての積層セラミックコンデンサの一実施の形態を模式的に示す断面図である。
【符号の説明】
１ 混合・粉砕工程
３ 仮焼工程
５ セラミック焼結体
６ａ〜６ｆ 内部電極
７ａ、７ｂ 外部電極[0001]
BACKGROUND OF THE INVENTION
  The present inventionIs productFor more information on layered electronic components,Mainly composed of complex oxide with perovskite structureThe present invention relates to a multilayer electronic component such as a multilayer ceramic capacitor.
[0002]
[Prior art]
Today, as a material for electronic components, the general formula ABO₃A composite oxide powder having a perovskite structure represented by the formula is widely known, and among them, BaTiO₃(Barium titanate) powder is widely used as a material for ceramic capacitors such as multilayer ceramic capacitors.
[0003]
This kind of BaTiO₃As a manufacturing method, BaCO has been conventionally used.₃(Barium carbonate) and TiO₂There is a solid phase method in which (titanium dioxide) is mixed and calcined and manufactured (for example, see Non-Patent Document 1).
[0004]
In Non-Patent Document 1, using a ball mill, BaCO₃And TiO₂And the resulting slurry is dried and then calcined using a pusher-type electric furnace or a rotary kiln.₃Is manufacturing.
[0005]
[Non-Patent Document 1]
Koichi Sasaki, “Production method and process of barium titanate and its composite particles”, Journal of Powder Engineering, Vol. 34 No. 11 (1997) p. 39-40
[0006]
[Problems to be solved by the invention]
By the way, in the above-mentioned multilayer ceramic capacitor, a thin dielectric ceramic layer (hereinafter referred to as “dielectric layer”) is required from the viewpoint of miniaturization, large capacity, and low cost. Regarding materials, base metal materials such as Ni and Cu have been used instead of noble metal materials such as Ag and Pd.
[0007]
And with the thinning of the dielectric layer, BaTiO that forms the dielectric layer₃The complex oxide powders such as fine particles are required to have fine grains and high tetragonality.
[0008]
Normally, the ceramic layer to be a dielectric layer contains various additives such as rare earth elements and silicon compounds from the viewpoint of improving characteristics and improving sinterability. When the base metal material is used for the internal electrode and fired in a reducing atmosphere, the solid solution of the additive in the composite oxide powder proceeds excessively. Abnormal grain growth occurs and the reliability is lowered.
[0009]
On the other hand, if the average particle size of the composite oxide powder increases even if the tetragonality is high, the average particle size of the ceramic particles also increases, so the reliability of the laminated ceramic capacitor with a thickness of 5 μm or less is reduced. To do.
[0010]
Therefore, in order to obtain a laminated ceramic capacitor having a reduced thickness, the composite oxide powder forming the dielectric layer is required to be fine and highly tetragonal.
[0011]
However, in the conventional solid-phase method as described in Non-Patent Document 1, since the calcination treatment is performed using a pusher type electric furnace or a rotary kiln, the calcination treatment time is long, and the composite oxide If the particle size of the powder is prioritized for atomization, the tetragonalization property is lowered. For this reason, when co-fired in a reducing atmosphere, the solid solution of the additive in the composite oxide powder proceeds excessively. As a result, the temperature characteristic of the capacitance deteriorates and abnormal grain growth of the ceramic particles occurs. There was a problem that it resulted in a decrease in reliability. In addition, there is a problem that a different phase other than the desired composite oxide powder is likely to be generated by a long calcination treatment.
[0012]
On the other hand, when trying to increase the tetragonality by giving priority to the crystallinity of the composite oxide powder, the average particle size becomes large. For this reason, the average particle size of the ceramic particles also increases, and the multilayer ceramic capacitor is thinned. In some cases, there is a problem that reliability is lowered.
[0013]
  The present invention has been made in view of such problems, and is a high-purity composite oxide having fine grains and high tetragonality.Is the product of whichAn object is to provide a layered electronic component.
[0014]
[Means for Solving the Problems]
  The inventors of the present invention have intensively studied to achieve the above object. As a result, the rate of temperature increase is 30 ° C./min (below) from the reaction start temperature at which the calcination synthesis reaction starts to the calcination maximum temperature. By setting at a high speed of 30 ° C./min) or higher, fine phases and high tetragonal high purity can be obtained without generating a heterogeneous phase.Has a perovskite structureComposite oxide powderobtainI got the knowledge that I can do it.The multilayer electronic component having a ceramic sintered body containing the composite oxide as a main component and containing at least one of magnesium oxide, manganese oxide, and silicon oxide as a subcomponent includes ceramic particles. No abnormal grain growth, high dielectric constant, good temperature characteristics of capacitance even when thinned, and a multilayer electronic component with various characteristics and excellent reliability can be obtained. I understood.
[0015]
  The present invention has been made on the basis of such knowledge, and relates to the present invention.The multilayer electronic component is a multilayer electronic component in which an internal electrode is embedded in a ceramic made of a dielectric ceramic composition, and an external electrode is formed on the surface of the ceramic. ₃ And a composite component containing at least one of magnesium oxide, manganese oxide, and silicon oxide as a subcomponent, and having the perovskite structure represented by For the oxide, the temperature rise rate of the mixed powder obtained by mixing the ceramic raw materials is set to 30 ° C./min or more from the reaction start temperature at which the synthesis reaction is started until it reaches the maximum calcining temperature. And calcined compositeIt is characterized by that.
[0016]
In addition, the above-described operational effect due to the high temperature rise is remarkable when the A site element is Ba, Ca, the B site element is Ti, Zr, and the total of the A site element and the B site element is three or more. .
[0017]
  Therefore, the present inventionMultilayer electronic components have the perovskite structure.A site element contains at least one of Ba and Ca, BThe site element contains at least one of Ti and Zr, and the A site element and the B site element have a total of 3 or more types.Composed ofIt is characterized by that.
[0018]
  Of the complex oxide powders, BaTiO₃Calcium-modified barium titanate (Ba) in which a part of Ba is substituted with Ca_1-xCa_x) TiO₃(Hereinafter referred to as “Ca-modified barium titanate”) is BaTiO.₃The Ca-modified barium titanate obtained by the above rapid temperature increase has fine and high tetragonal properties, and therefore has good temperature characteristics and a fine particle region. High dielectric constant and highly reliable laminationType electronic componentsCan be obtained. Furthermore, from the viewpoint of improving the characteristics, it is also preferable to add specific rare earth elements such as Y and Dy to the Ca-modified barium titanate as necessary.
[0019]
  That is, the present inventionIn the multilayer electronic component, the composite oxide before firing isGeneral formula (Ba_1-xyCa_xRe_yO)_mTiO₂(However, Re is at least one selected from Y, Gd, Tb, Dy, Ho, Er, and Yb, and 0.992 ≦ m ≦ 1.005, 0 <x ≦ 0.20, 0 ≦ y ≦ 0.06).
[0020]
That is, in order to obtain a finer Ca-modified barium titanate while maintaining high tetragonality, m is preferably set to 0.992 ≦ m ≦ 1.005, and the generation of a heterogeneous phase is completely achieved. In order to eliminate and reliably obtain higher-purity Ca-modified barium titanate, x and y are preferably 0 <x ≦ 0.20 and 0 ≦ y ≦ 0.06, respectively.
[0021]
Further, in order to obtain a finer composite oxide powder while maintaining the tetragonal property, the calcining step is performed under a reduced pressure atmosphere, for example, 7.98 × 10 6.⁴It is preferable to carry out at Pa or less.
[0022]
  That is, the present inventionIn the multilayer electronic component, the calcination is performed in a reduced pressure atmosphere.It is characterized by that.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described in detail.
[0030]
  As will be described later, the multilayer electronic component according to the present invention has an internal electrode embedded in a ceramic sintered body (porcelain) and an external electrode formed on the surface of the ceramic sintered body.
Therefore, first, a method for producing a composite oxide powder that is a main component of the ceramic sintered body will be described in detail.
  Figure 1The aboveIt is a manufacturing process figure which shows the manufacturing method of complex oxide powder.
[0031]
In the mixing and pulverizing step 1, a predetermined ceramic raw material is weighed, put into a ball mill containing a pulverizing medium such as partially stabilized zirconia (hereinafter referred to as “PSZ”), mixed, and wet pulverized.
[0032]
That is, as a ceramic raw material, a compound containing Ba or / and Ca constituting the A-site element (for example, BaCO₃, CaCO₃), A compound containing Ti and / or Zr constituting the B site element (for example, TiO₂, ZrO₂), And Dy as needed₂O₃A predetermined amount of each of the rare earth element compounds such as the above is weighed, and the weighed material is put together with water into a ball mill containing a grinding medium, and sufficiently mixed and pulverized wet to prepare a ceramic slurry.
[0033]
Next, the ceramic slurry is evaporated to dryness in the drying step 2 to obtain a mixed powder. In the subsequent calcining step 3, atmospheric pressure (1.01 × 10 6⁵Under Pa), the mixed powder is calcined with a predetermined calcining profile.
[0034]
FIG. 2 shows a calcining profile, in which the horizontal axis represents the calcining time (hr) and the vertical axis represents the calcining temperature (° C.).
[0035]
The calcining furnace is heated at an arbitrary heating rate until reaching the reaction start temperature T1 (for example, 400 ° C.) at which the synthesis reaction starts from the start of the calcining, and from the reaction start temperature T1 to the calcining maximum temperature T2 ( For example, the time t1 until reaching 1000 to 1100 ° C., the temperature rising rate is set to 30 ° C./min or higher and the temperature is increased rapidly, and then the calcining furnace is set at the calcining maximum temperature T2 for a predetermined time t2 ( (For example, 0.5 hour), and then the temperature is lowered to obtain a calcined product.
[0036]
The reason why the temperature increase rate at time t1 is set to 30 ° C./min or more is as follows.
[0037]
Usually, this type of calcination treatment is performed such that the maximum calcination temperature T2 of the calcination furnace is 1000 to 1100 ° C., and is maintained at the maximum calcination temperature T2 for a predetermined time (for example, 2 hours), Then the temperature of the calciner is lowered.
[0038]
However, when the rate of temperature increase is less than 30 ° C./min, it takes a long time to reach the maximum calcining temperature because the rate of temperature increase is slow. As a result, the atomic ratio c / a of the crystal axis is reduced and the tetragonality is lowered, resulting in a high-purity composite oxide that is finer and has high tetragonality. The powder cannot be obtained.
[0039]
On the other hand, when the rate of temperature increase is 30 ° C./min or higher, the time required for the calcination treatment is short because the rate of temperature increase is fast, and a desired composite oxide is synthesized in a short time, resulting in the formation of a heterogeneous phase. Therefore, it is possible to obtain a high-purity composite oxide powder that is fine and highly tetragonal.
[0040]
Therefore, in the present embodiment, the temperature increase rate at time t1 is set to 30 ° C./min or more to perform the calcination treatment, thereby obtaining a high-purity composite oxide having fine grains and high tetragonality. ing.
[0041]
The upper limit is not particularly limited as long as the rate of temperature rise is 30 ° C./min or more, but the upper limit of the rate of temperature rise is preferably 120 ° C./min or less from the viewpoint of equipment.
[0042]
Subsequently, it progresses to the crushing process 4, a crushing process is performed to a calcined material with a jet pulverizer etc., and, thereby, composite oxide powder is manufactured.
[0043]
And the manufacturing method mentioned above is BaTiO among composite oxide powders.₃It is practical and preferable to apply to a Ca-modified barium titanate represented by the following general formula (1) in which a part of Ba is substituted with Ca.
[0044]
(Ba_1-xyCa_xRe_yO)_mTiO₂  ... (1)
That is, Ca-modified barium titanate has a better temperature characteristic of capacitance than barium titanate, and its dielectric constant increases when it becomes fine particles. It is optimal as a ceramic raw material for capacitors.
[0045]
Here, the rare earth element Re is appropriately added to improve the characteristics, and at least one selected from Y, Gd, Tb, Dy, Ho, Er, and Yb can be used.
[0046]
The molar ratio m between the A site element (Ba, Ca, Re) and the B site element Ti is preferably 0.992 ≦ m ≦ 1.005. That is, by setting the molar ratio m within this range, it is possible to obtain finer Ca-modified barium titanate while maintaining high tetragonality.
[0047]
The molar ratio x of Ca in the A site is preferably 0 <x ≦ 0.20, and the molar ratio y of Re is preferably 0 ≦ y ≦ 0.06. That is, when the molar ratio x, y is out of this range, the content of Ca and Re becomes excessive, and CaTiO₃This is because a heterogeneous phase such as is easily generated.
[0048]
In the above embodiment, the calcining step 3 is performed at atmospheric pressure (1.01 × 10⁵Pa), but a reduced pressure atmosphere (for example, 7.98 × 10⁴(Pa or less) is also preferable. That is, by performing the calcination process in a reduced-pressure atmosphere, BaCO₃As a result, the decomposition start temperature of the ceramic raw material and the like is lowered, and crystallinity can be improved and further atomization can be achieved.
[0049]
Further, the ceramic raw material usually contains alkali metal, Zr, Al, and Si as impurities, but it is preferable that the total amount of these impurities is less than 0.5 wt%. That is, if the total amount of impurities in the ceramic raw material exceeds 0.5 wt%, these impurities may be dissolved in the ceramic main component and hinder high crystallization.
[0050]
  Next, the multilayer electronic component according to the present invention will be described in detail.
  FIG.the above1 is a cross-sectional view schematically showing an embodiment of a multilayer ceramic capacitor as a multilayer electronic component.
[0051]
In the multilayer ceramic capacitor, internal electrodes 6 (6a to 6f) are embedded in a ceramic sintered body 5 mainly composed of Ca-modified barium titanate, and external electrodes 7a are disposed at both ends of the ceramic sintered body 5. 7b, and first plating films 8a and 8b and second plating films 9a and 9b are formed on the surfaces of the external electrodes 7a and 7b.
[0052]
Specifically, the internal electrodes 6a to 6f are juxtaposed in the stacking direction, the internal electrodes 6a, 6c, and 6e are electrically connected to the external electrode 7a, and the internal electrodes 6b, 6d, and 6f are external electrodes 7b. And are electrically connected. A capacitance is formed between the opposing surfaces of the internal electrodes 6a, 6c, 6e and the internal electrodes 6b, 6d, 6f.
[0053]
The multilayer ceramic capacitor is manufactured as follows.
[0054]
First, in addition to the Ca-modified barium titanate represented by the general formula (1), a magnesium compound, a manganese compound, a silicon compound as a sintering aid, and additives such as a barium compound and a boron compound as necessary. A predetermined amount is weighed, and the weighed product is put into a ball mill together with a binder such as polyvinyl butyral resin and an organic solvent such as ethanol, and wet-mixed to prepare a ceramic slurry. Next, the ceramic slurry is molded by a doctor blade method or the like to produce a ceramic green sheet having a predetermined thickness.
[0055]
Next, an internal electrode conductive paste mainly composed of a base metal material such as Ni is printed on the ceramic green sheet by a screen printing method or the like to form an internal electrode conductive pattern.
[0056]
Next, a predetermined number of the ceramic green sheets on which the internal electrode conductive patterns are formed are appropriately stacked so that the lead portions of the conductive patterns are staggered to form a laminate.
[0057]
Subsequently, the laminate is heated to a temperature of 350 to 500 ° C. in a reducing atmosphere to perform a binder removal treatment, and thereafter an oxygen partial pressure of 10^-9-10^-12MPa H₂-N₂-H₂A firing process is performed at a temperature of about 1300 ° C. for about 2 hours in a reducing atmosphere composed of O to produce a ceramic sintered body 5 in which the internal electrode 6 is embedded.
[0058]
Next, an external electrode paste mainly composed of Ag or the like is applied to both ends of the ceramic sintered body 5 and subjected to a baking treatment at about 600 ° C. in a reducing atmosphere to form the external electrodes 7a and 7b.
[0059]
Thereafter, electrolytic plating or the like is performed to form first plating films 8a and 8b made of Ni or the like and second plating films 9a and 9b made of Sn, Sn alloy or the like, whereby a multilayer ceramic capacitor is manufactured. The
[0060]
As described above, the multilayer ceramic capacitor is added to the Ca-modified barium titanate since the ceramic sintered body 5 is mainly composed of fine-grained and tetragonal high-purity Ca-modified barium titanate. Additives (magnesium compounds, manganese compounds, silicon compounds, etc.) to the Ca-modified barium titanate are moderately suppressed, and it is possible to avoid deterioration of the temperature characteristics of the capacitance, and a high relative dielectric constant. Thus, it is possible to obtain a multilayer ceramic capacitor having excellent reliability with various characteristics.
[0061]
【Example】
Next, examples of the present invention will be specifically described.
[0062]
  In the first to fourth examples, composite oxides that are the main component raw materials of multilayer electronic components were produced, and the characteristics were evaluated.
[First embodiment]
  (Example A)
  As a ceramic raw material, BaCO₃, CaCO₃TiO₂Each powder is prepared and BaCO is used at a molar ratio.₃: CaCO₃: TiO₂= 0.95: 0.05: 1.00.
[0063]
Then, this weighed material was put into a ball mill containing PSZ having a diameter of 2 mm together with water, and wet pulverized for 72 hours to prepare a slurry. Then, this slurry was evaporated and dried to obtain a mixed powder.
[0064]
Next, this mixed powder was put into a calcining furnace and a calcining process was executed with three different calcining profiles to obtain a composite oxide powder.
[0065]
That is, first, the temperature of the calcining furnace is increased at a temperature increase rate of 5 ° C./min until the temperature in the furnace reaches 400 ° C., which is the reaction start temperature of the mixed powder, and then 2 ° C. at 1000 ° C. The calcined product was obtained by maintaining the temperature for a period of time and then lowering the temperature. Thereafter, the calcined product was crushed with a dry pulverizer to produce a composite oxide powder of Sample No. 1.
[0066]
Further, the temperature of the calcining furnace is increased at a rate of temperature increase of 30 ° C./min until the temperature in the furnace reaches 400 ° C. to 1100 ° C., and then maintained at a temperature of 1100 ° C. for 30 minutes, and then the temperature is decreased A calcined product was obtained, and then the calcined powder was crushed by a dry pulverizer to produce a composite oxide powder of Sample No. 2.
[0067]
Further, the temperature of the calcining furnace is increased at a rate of temperature increase of 5 ° C./min until the temperature in the furnace reaches 400 ° C. to 1100 ° C., then maintained at a temperature of 1100 ° C. for 2 hours, and then the temperature is decreased. A calcined powder was obtained, and then the calcined powder was crushed with a dry pulverizer to produce a composite oxide powder of Sample No. 3.
[0068]
Next, each sample obtained in this way is observed with a scanning electron microscope (SEM) to measure the average particle diameter, and an X-ray diffractometer (XRD). The constituent phase was confirmed in
[0069]
Table 1 shows calcination conditions and measurement results.
[0070]
[Table 1]

As is apparent from Table 1, sample number 1 is Ba having an average particle size of 0.3 μm._0.95Ca_0.05TiO₃Is obtained, but the rate of temperature rise is as slow as 5 ° C / min.₃And CaTiO₃The formation of heterogeneous phases was observed.
[0071]
On the other hand, sample No. 2 has a high temperature rising rate of 30 ° C./min, and therefore the calcining time can be shortened. Therefore, Ba having an average particle size of 0.3 μm is used._0.95Ca_0.05TiO₃A single phase consisting of was obtained.
[0072]
Sample No. 3 has the highest calcination maximum temperature of 1100 ° C._0.95Ca_0.05TiO₃A single phase was obtained, and the formation of heterogeneous phases was not observed, but the rate of temperature increase was as slow as 5 ° C / min, and the calcining treatment time was increased by increasing the maximum calcining temperature. The average particle size became as coarse as 0.4 μm.
[0073]
(Example B)
As a ceramic raw material, BaCO₃TiO₂, ZrO₂Each powder is prepared and BaCO is used at a molar ratio.₃: TiO₂: ZrO₂: = 1.00: 0.80: 0.20.
[0074]
Next, after the wet pulverization by the same method and procedure as in Example A, it is evaporated to dryness to obtain a mixed powder. Further, as in Example A, the calcination treatment is performed with three types of calcination profiles, and then The calcined powder was pulverized with a dry pulverizer to produce composite oxide powders of sample numbers 4-6.
[0075]
Next, each sample was observed by SEM, the average particle diameter was measured, and the constituent phases were confirmed by XRD.
[0076]
Table 2 shows calcination conditions and measurement results.
[0077]
[Table 2]

As apparent from Table 2, Sample No. 4 is BaTi having an average particle size of 0.3 μm._0.80Zr_0.20O₃Is obtained, but the rate of temperature rise is as low as 5 ° C./min.₃The formation of heterogeneous phases was observed.
[0078]
On the other hand, Sample No. 5 has a high temperature rising rate of 30 ° C./min, and therefore the calcining time is short, and BaTi having an average particle size of 0.3 μm._0.80Zr_0.20O₃A single phase consisting of was obtained.
[0079]
Sample No. 6 has a BaTi maximum temperature as high as 1100 ° C._0.80Zr_0.20O₃A single phase was obtained, and the formation of heterogeneous phases was not observed, but the rate of temperature increase was as slow as 5 ° C / min, and the calcining treatment time was increased by increasing the maximum calcining temperature. The average particle size became as coarse as 0.5 μm.
[0080]
(Example C)
As a ceramic raw material, CaCO₃TiO₂, ZrO₂Each powder was prepared and CaCO was used at a molar ratio.₃: TiO₂: ZrO₂: = 1.00: 0.65: 0.35.
[0081]
Next, after wet-grinding by the same method and procedure as Example A, evaporating and drying to obtain a mixed powder, and similarly to Example A, calcination treatment is performed with three types of calcination profiles, and then dry-type The calcined powder was pulverized with a pulverizer to produce composite oxide powders of sample numbers 7-9.
[0082]
Next, each sample was observed by SEM, the average particle diameter was measured, and the constituent phases were confirmed by XRD.
[0083]
Table 3 shows calcination conditions and measurement results.
[0084]
[Table 3]

As apparent from Table 3, Sample No. 7 is CaTi having an average particle size of 0.3 μm._0.65Zr_0.35O₃Is obtained, but the heating rate is slow at 5 ° C./min.₃The formation of heterogeneous phases was observed.
[0085]
On the other hand, Sample No. 8 has a high temperature rising rate of 30 ° C./min. Therefore, the calcining time is short, and CaTi having an average particle size of 0.3 μm is used._0.65Zr_0.35O₃A single phase consisting of was obtained.
[0086]
Sample No. 9 has a CaTi maximum temperature as high as 1100 ° C._0.65Zr_0.35O₃A single phase was obtained, and the formation of heterogeneous phases was not observed, but the rate of temperature increase was as slow as 5 ° C / min, and the calcining treatment time was increased by increasing the maximum calcining temperature. The average particle size became as coarse as 0.5 μm.
[0087]
That is, as is clear from Examples A to C, the time required to reach the maximum calcining temperature (1000 ° C. to 1100 ° C.) from the reaction start temperature (400 ° C.) and the temperature rising rate were set to 5 ° C./min. When the temperature of the calcining furnace is raised, the calcining treatment time is long, so a heterogeneous phase is generated or the particle size becomes coarse, while the temperature rising rate is set to 30 ° C./min. It was found that when the temperature of the calcining furnace is raised, the calcining treatment time is short, so that it is possible to obtain a high-purity composite oxide powder that is finer and does not generate a different phase.
[0088]
[Second Embodiment]
BaCO as a ceramic raw material₃, CaCO₃TiO₂Each powder was prepared and the composition formula (Ba_0.946Ca_0.060) TiO₃Each powder was weighed so as to obtain a composite oxide powder, and a mixed powder was obtained by the same method and procedure as in the first example.
[0089]
Next, this mixed powder was put into a calcining furnace and subjected to a calcining treatment with three different calcining profiles to produce a composite oxide powder.
[0090]
That is, first, the temperature of the calciner is increased at a rate of temperature increase of 5 ° C./min until the temperature in the furnace reaches from 400 ° C. to 1000 ° C., and then held at a temperature of 1000 ° C. for 2 hours, and then the temperature is decreased. Then, the calcined product was obtained, and then the calcined product was crushed with a dry pulverizer to produce a composite oxide powder of Sample No. 11.
[0091]
Further, the temperature of the calcining furnace is increased at a rate of temperature increase of 10 ° C./min until the temperature in the furnace reaches 400 ° C. to 1050 ° C., and then maintained at a temperature of 1050 ° C. for 1 hour, and then the temperature is decreased. A calcined product was obtained, and then the calcined product was pulverized with a dry pulverizer to prepare a composite oxide powder of Sample No. 12.
[0092]
Further, the temperature of the calcining furnace is increased at a rate of temperature increase of 30 ° C./min until the temperature in the furnace reaches 400 ° C. to 1100 ° C., and then the temperature is maintained at 1100 ° C. for 30 minutes and then the temperature is decreased. Thereafter, the calcined product was pulverized with a dry pulverizer to prepare a composite oxide powder of Sample No. 13.
[0093]
Next, as a ceramic raw material, BaCO₃, CaCO₃And TiO₂In addition to each powder of Dy₂O₃Prepare powder and formula (Ba_0.926Ca_0.060Dy_0.020) TiO₃Each powder was weighed so that a composite oxide powder was obtained, and a mixed powder was obtained in the same manner as described above.
[0094]
Next, this mixed powder was put into a calcining furnace and subjected to calcining treatment with two different calcining profiles to produce a composite oxide powder.
[0095]
That is, first, the temperature of the calciner is increased at a rate of temperature increase of 5 ° C./min until the temperature in the furnace reaches from 400 ° C. to 1000 ° C., and then held at a temperature of 1000 ° C. for 2 hours, and then the temperature is decreased. Then, the calcined product was obtained, and then the calcined product was crushed with a dry pulverizer to prepare a composite oxide powder of Sample No. 14.
[0096]
Further, the temperature of the calcining furnace is increased at a rate of temperature increase of 30 ° C./min until the temperature in the furnace reaches 400 ° C. to 1100 ° C., and then maintained at a temperature of 1100 ° C. for 30 minutes, and then the temperature is decreased. A fired product was obtained, and then the calcined product was crushed with a dry pulverizer to prepare a composite oxide powder of Sample No. 15.
[0097]
Next, with respect to sample numbers 11 to 15, the average particle diameter is measured by SEM observation, further, a diffraction pattern is obtained by XRD, the Rietveld analysis is performed, the crystal structure is analyzed, and the axial ratio c / a of the crystal axis is calculated. did.
[0098]
Table 4 shows the composition components, calcining conditions, average particle diameter, and axial ratio c / a of each sample.
[0099]
[Table 4]

Each sample had an average particle size of 0.30 μm.
[0100]
Sample No. 11 has a slow temperature rise rate of 5 ° C./min, and thus requires a long time for the calcining treatment. For this reason, the axial ratio c / a is as small as 1.008, and the tetragonality is low. . This is because the calcination time is long, so BaTiO₃It is considered that Ca, which is a different element, was dissolved in the ordered atomic arrangement, resulting in disorder in the atomic arrangement and a reduction in the axial ratio c / a.
[0101]
In Sample No. 12, although the rate of temperature increase was increased to 10 ° C./min, the rate of temperature increase was still insufficient, so that the axial ratio c / a was as small as 1.008, and tetragonal properties were obtained. Was found to be low.
[0102]
On the other hand, sample No. 13 raises the heating rate to 30 ° C./min to cause the calcining synthesis reaction, so that the axial ratio c / a is 1. without causing the average particle size to become coarse. It can be increased to 009, and it has been found that the tetragonality can be improved.
[0103]
Furthermore, sample No. 14 has a slow rate of temperature increase of 5 ° C./min, as in sample No. 11, and therefore requires a long time for the calcining treatment. Therefore, the axial ratio c / a is as small as 1.008 and square. It was found that the crystallinity was lowered.
[0104]
On the other hand, sample number 15 raises the temperature rising rate to 30 ° C./min to cause the calcining synthesis reaction as in sample number 13, so that the axial ratio c does not cause the average particle size to become coarse. It was found that / a can be increased to 1.09, and the tetragonality can be improved.
[0105]
[Third embodiment]
Ca-modified barium titanate (Ba) under the calcining conditions of a heating rate of 30 to 60 ° C./min, a calcining maximum temperature of 1050 to 1100 ° C., and a holding time of 0.5 hr._xCa_y) TiO₃Sample Nos. 21 to 26 composite oxide powders were prepared.
[0106]
In the third embodiment, the y value is constant, and the molar ratio m of (Ba, Ca) that is the A site element and Ti that is the B site element is different between 0.991 and 1.006. Thus, Ba / Ti is changed.
[0107]
In addition, as a comparative example, a mixed powder having the same composition as sample No. 23 was subjected to a calcining process under the same calcining conditions as Sample Nos. 11 and 12, and composite oxide powders of Sample Nos. 27 and 28 were produced.
[0108]
Next, as in the second example, the average particle diameter was measured for each sample, and the axial ratio c / a of the crystal axes was calculated.
[0109]
Table 5 shows the composition components, calcining conditions, average particle diameter, and axial ratio c / a of each sample.
[0110]
[Table 5]

As is apparent from Table 5, since sample numbers 21 to 26 are set to a temperature rising rate of 30 ° C. to 60 ° C./min and perform high temperature heating, the axial ratio c / a is 1.009. Sample Nos. 22 to 24 and 27 having a high tetragonal crystallinity but having a molar ratio m adjusted to 0.992 ≦ m ≦ 1.005 have an average particle size of 0.25 μm. From the viewpoint of further atomization while maintaining high tetragonality, it was found that the molar ratio m is preferably 0.992 ≦ m ≦ 1.005. .
[0111]
Sample Nos. 27 and 28 have slow heating rates of 5 ° C./min and 10 ° C./min, respectively, and thus require a long time for the calcining treatment. Therefore, the axial ratio c / a becomes 1.008 and the tetragonal crystal. It was found that the sex decreased.
[0112]
In addition, when the present inventors conducted a separate experiment, when the molar ratio x of Ca to Ti was 0.21, and when the molar ratio y of Dy to Ti was 0.07, both were Ca to Ti. Even if the content of Ca and Dy becomes excessive, and the calcination treatment is carried out at a heating rate of 30 ° C./min, CaTiO₃The formation of heterogeneous phases was confirmed.
[0113]
[Fourth embodiment]
First, BaCO₃, CaCO₃TiO₂Each powder of (Ba_0.938Ca_0.060) TiO₃Were weighed and mixed to obtain
[0114]
Next, the furnace pressure was set to atmospheric pressure (1.01 × 10⁵Pa), the temperature of the calcining furnace is increased at a temperature increase rate of 5 ° C./min until the temperature in the furnace reaches from 400 ° C. to 950 ° C., and then held at a temperature of 950 ° C. for 30 minutes. Thus, the calcined product was obtained, and then the calcined product was crushed with a dry pulverizer to prepare a composite oxide powder of Sample No. 31.
[0115]
Also, the furnace pressure was 7.98 × 10⁴The pressure was reduced to Pa, and calcining was performed under the same calcining conditions as in Sample No. 31 to obtain a calcined product. Thereafter, the calcined product was crushed with a dry pulverizer to prepare a composite oxide powder of Sample No. 32.
[0116]
Also, the furnace pressure is set to atmospheric pressure (1.01 × 10⁵Pa), the temperature of the calcining furnace is increased at a temperature increase rate of 30 ° C./min until the temperature in the furnace reaches from 400 ° C. to 1050 ° C., and then held at 1050 ° C. for 30 minutes, and then the temperature is decreased Thus, the calcined product was obtained, and then the calcined product was crushed with a dry pulverizer to prepare a composite oxide powder of Sample No. 33.
[0117]
Also, the furnace pressure was 7.98 × 10⁴The pressure was reduced to Pa, a calcining treatment was performed under the same calcining conditions as in Sample No. 33 to obtain a calcined product, and then the calcined product was crushed with a dry pulverizer to produce a composite oxide powder of Sample No. 34.
[0118]
Next, as in the second example, the average particle diameter was measured for each sample, and the axial ratio c / a of the crystal axes was calculated.
[0119]
Table 6 shows the composition components, calcining conditions, average particle diameter, and axial ratio c / a of each sample.
[0120]
[Table 6]

Sample No. 31 is calcined under atmospheric pressure at a heating rate of 5 ° C./min, so the average particle size is 0.25 μm and fine particles, but the axial ratio c / a is 1.007. It was found that the tetragonality was small.
[0121]
Sample No. 32 has a furnace internal pressure of 7.98 × 10⁴By reducing the pressure to Pa, the axial ratio c / a is improved to 1.008, but the tetragonal nature is still insufficient.
[0122]
On the other hand, sample No. 33 has a high tetragonal crystal ratio c / a as large as 1.009 because the internal pressure of the calcining furnace is atmospheric pressure but the temperature rising rate is 30 ° C./min. Sex can be obtained.
[0123]
Furthermore, in the sample number 34, the internal pressure of the calcining furnace is 7.98 × 10.⁴Since the pressure is reduced to Pa, the average particle size is further atomized to 0.20 μm while maintaining the high tetragonality with the axial ratio c / a of 1.09. Therefore, by reducing the furnace pressure, It has been found that it is possible to obtain a composite oxide powder with even finer and higher tetragonal properties.
[0124]
  [Fifth embodiment]
  In this fifth example, a multilayer ceramic capacitor was produced using the composite oxide powder, and the characteristics were evaluated.
  That is, first,Sample No. 11 (second example, Table 4) and composite oxide powder of sample number 13 (second example, Table 4), and Sample No. 23 (third example, Table 5) and sample number A composite oxide powder of 34 (fourth example, Table 6) was prepared.
[0125]
Next, with respect to 100 parts by weight of these composite oxide powders, Y₂O₃1.86 parts by weight, MgO 0.336 parts by weight, BaCO₃1.28 parts by weight, SiO₂0.74 parts by weight, MnO₂0.327 parts by weight, and B₂O₃Was added in an amount of 0.312 parts by weight, and a polyvinyl butyral binder and an organic solvent such as ethanol were added and wet mixed by a ball mill to prepare a ceramic slurry.
[0126]
Next, this ceramic slurry was formed by a doctor blade method to produce a ceramic green sheet.
[0127]
Next, on the ceramic green sheet, a conductive paste for an internal electrode containing Ni as a main component is screen-printed to form an internal electrode layer, and the ceramic green sheet on which the internal electrode layer is further formed A plurality of stacked layers were prepared so that the lead-out portions of the layers were staggered.
[0128]
And this laminated body is N₂After heating to 350 ° C. in an atmosphere to decompose the binder and remove the binder, the oxygen partial pressure is 10^-9-10^-12MPa H₂-N₂-H₂The ceramic sintered body was obtained by firing at 1300 ° C. for 2 hours in a reducing atmosphere composed of O gas.
[0129]
Then B₂O₃-Li₂O-SiO₂-Preparing a conductive paste for external electrodes mainly composed of Ag containing a BaO-based glass material, applying the conductive paste for external electrodes to both end faces of the ceramic sintered body,₂Baking treatment was performed at a temperature of 600 ° C. in an atmosphere, whereby external electrodes were formed, and multilayer ceramic capacitors of sample numbers 11 ′, 13 ′, and 23′34 ′ were produced.
[0130]
The outer dimensions of the produced multilayer ceramic capacitor were 1.6 mm in length, 3.2 mm in width, and 1.2 mm in thickness. The thickness of the dielectric layer of the multilayer ceramic capacitor was 5 μm, and the number of effective dielectric layers was 100. Moreover, the counter electrode area per layer is 2.1 mm.²Met.
[0131]
Next, each of the above samples was subjected to a dielectric constant at room temperature, dielectric loss, rate of change of capacitance with respect to temperature change (hereinafter referred to as “capacitance change rate”), and high temperature load life test.
[0132]
Here, dielectric constant and dielectric loss were measured with an automatic bridge type measuring instrument,
The capacitance change rate was measured by measuring the capacitance change rate at 125 ° C. with the capacitance at 25 ° C. as a reference value.
[0133]
Further, the high temperature load life test was performed by adjusting the applied voltage so that the temperature was 150 ° C. and the electric field strength was 15 KV / mm, and measuring the change in insulation resistance with time. That is, 30 samples were sampled, the time when the insulation resistance became 200 kΩ or less was judged as the life of the sample, the average time was calculated, and the high temperature load life was evaluated.
[0134]
Table 7 shows the measurement results.
[0135]
[Table 7]

Sample No. 11 ′ has an axial ratio c / a as small as 1.008 (see Table 4), and therefore has a low tetragonality.₂O₃Additives such as MgO and the like are excessively dissolved in the composite oxide powder. Therefore, the relative dielectric constant is as high as 2750, but the dielectric loss is as large as 4.6%, and the capacitance change rate is also large as −16.8%. . That is, according to the standard of EIA (American Electronics Industry Association), in a high dielectric constant type multilayer ceramic capacitor, the capacitance change rate at −55 to 125 ° C. with respect to 25 ° C. needs to be within ± 15%. (X7R characteristics), however, it was found that the sample number 11 'exceeded -15%, the temperature characteristics deteriorated, and the X7R characteristics were not satisfied. In addition, the average life under high temperature load is as short as 17.6 hours and lacks durability under high temperature load.
[0136]
On the other hand, sample numbers 13 ′, 23 ′ and 34 ′ all have an axial ratio c / a of 1.009 (see Tables 4, 5 and 6), and have high tetragonality.₂O₃Thus, solid solution of additives such as MgO and the like in the composite oxide powder is moderately suppressed, and thus the rate of change in capacity is also -12.5 to -12.8%, and can be suppressed to within -15%. In addition, the dielectric constant, dielectric loss, and durability at high temperature load can be satisfied.
[0137]
Sample Nos. 13 ′, 23 ′ and 34 ′ can ensure a good temperature characteristic of the capacitance, and have good relative dielectric constant, dielectric loss, and durability under high temperature load. The average particle size of 13 ′ is 0.30 μm (see Table 4), the average particle size of sample number 23 ′ is 0.25 μm (see Table 5), and the average particle size of sample number 34 ′ is 0.20 μm. (Refer to Table 6) As the average particle diameter becomes finer, the dielectric loss and the resistance become smaller, and the average life at high temperature load becomes longer.
[0138]
That is, from Sample Nos. 13 ′, 23 ′, and 34 ′, the more the average particle size is reduced, the lower the dielectric loss and the durability at high temperature load. It was confirmed that it can be obtained.
[0139]
【The invention's effect】
  As described in detail above, the present inventionThe multilayer electronic component is a multilayer electronic component in which an internal electrode is embedded in a porcelain made of a dielectric ceramic composition and an external electrode is formed on the surface of the porcelain. ₃ And a composite component containing at least one of magnesium oxide, manganese oxide, and silicon oxide as a subcomponent, and having the perovskite structure represented by For the oxide, the temperature rise rate of the mixed powder obtained by mixing the ceramic raw materials is set to 30 ° C./min or more during the period from the reaction start temperature at which the synthesis reaction starts to the maximum calcining temperature. And calcined composite,The calcining time is short, no heterogeneous phase is generated, and a high-purity composite oxide powder with fine grains and high tetragonality can be produced. And thisMulti-layer ceramic capacitor with high relative dielectric constant, excellent capacitance and low capacitance change rate with respect to temperature change, excellent dielectric properties, durability at high temperature load, etc. and excellent reliability It is possible to obtain a multilayer electronic component such as the above.
[0140]
  Also,Of the perovskite structureA site element contains at least one of Ba and Ca, BThe site element contains at least one of Ti and Zr, and the A site element and the B site element have a total of 3 or more types.Composed ofIn this case, the above effects can be easily achieved.
[0141]
  AlsoThe composite oxide before firing isGeneral formula (Ba_1-xyCa_xRe_yO)_mTiO₂(However, Re is at least one selected from Y, Gd, Tb, Dy, Ho, Er, and Yb, and 0.992 ≦ m ≦ 1.005, 0 <x ≦ 0.20, 0 ≦ y ≦ 0.06), so a multilayer electronic component such as a multilayer ceramic capacitor having a high relative dielectric constant in a fine particle regionGetCan.
[0142]
  Also,The calcination is performed under a reduced pressure atmosphere.For example, 7.98 × 10⁴By carrying out at Pa or less, the composite oxide powder further atomized while maintaining high tetragonalityobtainbe able to.
[Brief description of the drawings]
FIG. 1 is a production process diagram showing one embodiment of a method for producing a composite oxide powder according to the present invention.
FIG. 2 is a diagram showing a calcining profile in a calcining step.
FIG. 3 is a cross-sectional view schematically showing an embodiment of a multilayer ceramic capacitor as a multilayer electronic component manufactured using the composite oxide powder.
[Explanation of symbols]
1 Mixing and grinding process
3 calcination process
5 Ceramic sintered body
6a-6f Internal electrode
7a, 7b External electrode

Claims (4)

In a multilayer electronic component in which an internal electrode is embedded in a ceramic made of a dielectric ceramic composition, and an external electrode is formed on the surface of the ceramic,
  The porcelain has the general formula ABO ₃ And containing at least one of magnesium oxide, manganese oxide, and silicon oxide as subcomponents, with a composite oxide having a perovskite structure represented by
  In addition, the composite oxide before firing has a temperature increase rate of 30 for the mixed powder obtained by mixing the ceramic raw materials until the temperature reaches the calcination maximum temperature from the reaction start temperature at which the synthesis reaction starts. A laminated electronic component, characterized in that it is a composite that has been calcined at a temperature of at least ° C / min. The A site element of the perovskite structure includes at least one of Ba and Ca , the B site element includes at least one of Ti and Zr, and the A site element and the B site element are: 2. The multilayer electronic component according to claim 1, wherein the total is composed of three or more elements . The composite oxide before firing is selected from the general formula (Ba _1-xy Ca _x Re _y O) _m TiO ₂ (where Re is selected from Y, Gd, Tb, Dy, Ho, Er, and Yb). The laminate according to claim 1 or 2 , wherein at least one of them is 0.992 ≦ m ≦ 1.005, 0 <x ≦ 0.20, 0 ≦ y ≦ 0.06). Type electronic components. 4. The multilayer electronic component according to claim 1 , wherein the calcination is performed in a reduced pressure atmosphere .

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