JP2004018365A

JP2004018365A - Microwave dielectric porcelain composition and method for producing the porcelain

Info

Publication number: JP2004018365A
Application number: JP2002180549A
Authority: JP
Inventors: Tetsuo Miyazono; 宮園　哲郎; Toru Okui; 奥井　徹; Toshiyuki Ushio; 牛尾　俊幸; Toshiaki Uki; 宇木　利明
Original assignee: Nippon Tungsten Co Ltd
Current assignee: Nippon Tungsten Co Ltd
Priority date: 2002-06-20
Filing date: 2002-06-20
Publication date: 2004-01-22
Anticipated expiration: 2022-06-20
Also published as: JP3793485B2

Abstract

【課題】εｒおよびＱｆが高く、τｆがゼロから正負に自由に制御できる。そしてＢｉ、Ｌｉ成分の蒸発を制御でき安定したマイクロ波誘電体磁器組成物とその磁器の製造方法を提供する。
【解決手段】基本組成成分が、酸化物換算で、ａＴｉＯ_２−ｂＳｒＯ−ｃＢａＯ−ｄＣａＯ−ｅＢｉ_２Ｏ_３−ｆＬｉ_２Ｏ−ｇＬｎ_２Ｏ_３（ＬｎはＬａ、Ｐｒ、Ｎｄ、Ｓｍのランタニド族元素から選択される１種または２種以上）で表され、ａ＋ｂ＋ｃ＋ｄ＋ｅ＋ｆ＋ｇ＝１００モル％とした場合に、ａ〜ｇのそれぞれが、モル％で、４５≦ａ≦７１、０．４≦ｂ≦６、０．２≦ｃ≦１８、０．２≦ｄ≦１８、０．２≦ｅ≦１０、１≦ｆ≦１３、２≦ｇ≦１５の範囲内にあり、かつ、ｂＳｒＯとｃＢａＯ、ｂＳｒＯとｄＣａＯのそれぞれの配合比率が、ｂ：ｃが１：０．３〜１：２０およびｂ：ｄが１：０．３〜１：２０である。さらに、酸化物換算でＭｎＯ_２、Ｆｅ_２Ｏ_３、Ｃｏ_３Ｏ_４、Ｎｂ_２Ｏ_５、Ｔａ_２Ｏ_５の中の１種または２種以上を合計を０．１〜１０重量部を添加物として含有できる。
【選択図】　なしThe present invention has a high εr and Qf, and can freely control τf from zero to positive or negative. Further, the present invention provides a stable microwave dielectric porcelain composition capable of controlling evaporation of Bi and Li components and a method for producing the porcelain.
A basic composition component, in terms of _{oxide, aTiO 2 -bSrO-cBaO-dCaO} -eBi 2 O 3 -fLi 2 O-gLn 2 O 3 (Ln is La, Pr, Nd, lanthanides of Sm And when a + b + c + d + e + f + g = 100 mol%, each of a to g is mol%, and 45 ≦ a ≦ 71, 0.4 ≦ b ≦ 6, 0.2 ≦ c ≦ 18, 0.2 ≦ d ≦ 18, 0.2 ≦ e ≦ 10, 1 ≦ f ≦ 13, 2 ≦ g ≦ 15, and bSrO and cBaO, bSrO and dCaO Are b: c of 1: 0.3 to 1:20 and b: d of 1: 0.3 to 1:20. Further, one or more of MnO ₂ , Fe ₂ O ₃ , Co ₃ O ₄ , Nb ₂ O ₅ , and Ta ₂ O ₅ in terms of oxide are added in a total amount of 0.1 to 10 parts by weight. Can be contained.
[Selection diagram] None

Description

【０００１】
【発明の属する技術分野】
本発明は、マイクロ波誘電体、とくに、マイクロ波やミリ波等の高周波領域において使用される種々の共振器材料、フィルター材料、ＭＩＣ用誘電体基板材料、アンテナ材料、積層チップコンデンサー材料、アイソレータ材料等の携帯電話部品の容量素子等に用いることができるマイクロ波誘電体磁器組成物およびその磁器の製造方法に関する。
【０００２】
【従来技術】
近年、通信技術の進歩により、自動車電話や携帯電話、ＰＨＳ等の移動体通信システム、ＧＰＳが急速に普及している。そのため通信機に利用される周波数帯域が拡大し、マイクロ波帯域での利用が盛んになっている。
【０００３】
このマイクロ波帯域で使用される回路には、空洞共振器、アンテナ等の部品が用いられていた。しかし、これらの部品はマイクロ波の波長と同程度の大きさになるため、自動車用電話機、携帯電話機および小型ＧＰＳ装置等に適用できるような部品の小型化は不可能であった。
【０００４】
これに対し、近年のマイクロ波フィルターや発信器の周波数安定化回路に誘電体共振器を用いることによって回路部品の小型化が盛んに行われ一般化しつつある。このような誘電体共振器に用いられる誘電体材料には、使用周波数帯域における誘電率（εｒ）が高く、マイクロ波帯域での無負荷品質係数（Ｑ）と共振周波数（ｆ０）との積（Ｑ×ｆ０、以下、Ｑｆと略称する。）が高く、かつ共振周波数の温度係数（τｆ：ｐｐｍ／℃）がゼロを中心に正から負に自由に制御できることが強く要望され、携帯電話部品等に用いられる容量素子材には、εｒが１４０以上、Ｑｆが１７００ＧＨｚ以上さらにはτｆが任意に制御可能であることがとくに重要である。
【０００５】
また、最近では使用される基板（容量素子材）も、さらに軽薄化が進み、基板厚みも０．０５ｍｍｔとなりつつあるが、材料中に存在するポアの形状、大きさ、個数等で容量値（コンデンサー）にバラツキやショート品が発生する問題があり材料中のポアの制御も必要不可欠であった。
【０００６】
このようなマイクロ波誘電体磁器組成物として、例えば、特開平５−２１１００７号公報には、組成Ｌｉ_２Ｏ−ＣａＯ−Ｌｎ_２Ｏ_３−ＴｉＯ_２で示され、ＬｎがＮｄまたはＳｍであるマイクロ波誘電体磁器組成物が開示されている。この開示された組成物の特性として、εｒが１４１、Ｑｆが１２１５ＧＨｚ、τｆが＋２５ｐｐｍ／℃があり、τｆの制御がなされているものでは、εｒが１００前後と低いものが示されている。
【０００７】
また、特開平６−２４３７２２号公報には、組成がＬｉ_２Ｏ−ＣａＯ−Ｓｍ_２Ｏ_３−Ｌｎ_２Ｏ_３−ＴｉＯ_２で示され、ＬｎがＮｄ、ＬａまたはＰｒであるマイクロ波誘電体磁器組成物が開示されており、その特性としては、εｒが１３０、Ｑｆが１３００ＧＨｚ、τｆが＋３０ｐｐｍ／℃であるものが示されている。
【０００８】
さらには、特開平９−２０８３０３号公報には、ＢａＯ−ＳｒＯ−Ｓｍ_２Ｏ_３−Ｂｉ_２Ｏ_３−Ｌａ_２Ｏ_３−ＴｉＯ_２系のマイクロ波誘電体磁器組成物が開示され、その特性としては、εｒが１４０、Ｑｆが１６５０ＧＨｚ、τｆが＋３７ｐｐｍ／℃であることが示されている。
【０００９】
【発明が解決しようとする課題】
しかしながら、上記特開平５−２１１００７号に開示された組成物は、εｒは１４１と高いが、Ｑｆは１２１５と低く、且つ、τｆが±１５ｐｐｍ／℃以内には制御しきれていない。また、τｆが±１５ｐｐｍ／℃以内での制御ではεｒは１００前後と低い値に留まっている。
【００１０】
また、特開平６−２４３７２２号に開示された組成物は、Ｓｍ_２Ｏ_３をＮｄ_２Ｏ３、Ｌａ_２Ｏ_３、Ｐｒ_６Ｏ_１１のいずれか１種に置換することによりεｒを１３０を保ってはいるが、τｆが＋３０ｐｐｍ／℃と大きく、τｆを±１０ｐｐｍ／℃に制御すると、εｒが１２５となり、Ｑｆも低下してしまうという問題がある。
【００１１】
さらに、特開平９−２０８３０３号に開示された組成物は、εｒが１４０、Ｑｆが１６５０と共に高い特性を示すが、τｆは＋３７ｐｐｍ／℃と大きいという問題がある。
【００１２】
このように、以上の従来技術では、何れも、近年の小型化に要求されているεｒ≧１４０、Ｑｆ≧１７００、τｆ≦１５ｐｐｍ／℃、さらには正負に任意の値に制御できるという要求特性を同時に満足できる材料を得ることができないものであった。
【００１３】
その最大の要因は含有されているＢｉ、Ｌｉ成分の高温焼成中における蒸発による組成比のバラツキが大きく量産化工程において安定しない事が大きな要因であった。
【００１４】
本発明が解決しようとする課題は、上記マイクロ波誘電体の小型化に際しての、要求特性、すなわち、マイクロ波、ミリ波等の高周波領域において、比誘電率εｒとＱｆ、さらには、共振周波数の温度係数τｆを安定して制御でき、量産化において特性バラツキの小さい量産化に適したマイクロ波誘電体磁器を得ることにある。
【００１５】
【課題を解決するための手段】
本発明のマイクロ波誘電体磁器組成物は、基本組成成分が、酸化物換算で、ａＴｉＯ_２−ｂＳｒＯ−ｃＢａＯ−ｄＣａＯ−ｅＢｉ_２Ｏ_３−ｆＬｉ_２Ｏ−ｇＬｎ_２Ｏ_３（ＬｎはＬａ、Ｐｒ、Ｎｄ、Ｓｍのランタニド族元素から選択される１種または２種以上）で表わされ、
ａ＋ｂ＋ｃ＋ｄ＋ｅ＋ｆ＋ｇ＝１００モル％とした場合に、ａ〜ｇのそれぞれが、モル％で、４５≦ａ≦７１、０．４≦ｂ≦６、０．２≦ｃ≦１８、０．２≦ｄ≦１８、０．２≦ｅ≦１０、１≦ｆ≦１３、２≦ｇ≦１５の範囲内にあり、
且つ、
ｂＳｒＯとｃＢａＯ、ｂＳｒＯとｄＣａＯのそれぞれの配合比率が、
ｂ：ｃが１：０．３〜１：２０および
ｂ：ｄが１：０．３〜１：２０
であることを特徴とする。
【００１６】
ＴｉＯ_２は、マイクロ波誘電体磁器としての基本的な成分としての機能を有する。その含有量が、４５モル％未満ではεｒの低下をきたし目的とする高いεｒを得ることができない。また７１モル％を超えるとτｆが正に大きく、Ｑｆも１０００以下と低くなり好ましくない。
【００１７】
ＳｒＯは、高周波領域において安定した電気特性を有する。その含有量が０．４モル％未満であるとεｒが低下し、さらにτｆをゼロから正負に自由に制御する効果が乏しくなる。また、６モル％を超えるとεｒが高くなるがＱｆが１０００以下となりτｆを目的の値に制御することが困難となる。
【００１８】
ＢａＯは、磁器の結晶粒子径を小さくすると共にεｒの値を制御する作用を有する。所定の範囲内で目的の誘電特性を得ることが可能になる。その含有量が０．２モル％未満では、磁器の結晶粒子径を小さく制御する作用が乏しく、その結果容量素子などに作製した場合、高温負荷寿命においてＱの劣化をきたす。また１８モル％を超えると、結晶粒子径が著しく成長し機械的強度が低下するため電子部品の軽薄化への要望にそぐわなくなる。さらに高温負荷寿命においてεｒ、Ｑｆ共に不安定になる。
【００１９】
ＣａＯ成分は磁器の結晶粒子径を小さくする作用があり、その結果機械的強度を高め安定にする。さらに高周波領域におけるＱｆを高くする作用があり、ＳｒＯ成分との配合比率を変化させることによって１ＫＨｚ〜０．１ＧＨｚの周波数領域の容量素子の温度と周波数の関係に対するＣ（容量値）、Ｑ（無負荷損失係数）、Ｃ−ＴＣ（容量値の温度特性）の変化の温度特性、とくに、２０℃〜８０℃付近の温度特性を著しく安定にすることができる。ＣａＯの含有量が、０．２モル％未満では磁器の結晶粒子径を小さくする効果が乏しく、その結果機械的強度が向上せず、さらに高周波領域のＱｆが低下する。そしてτｆの温度特性も不安定になる。また、１８モル％を超えるとεｒの低下をきたし、τｆを目的の値に制御することが困難になる。
【００２０】
ＳｒＯ成分とＢａＯとＣａＯの特定モル％範囲内での配合比率の変化は１〜７ＧＨｚ帯高周波領域）の周波数の変化に対して、Ｑｆおよびτｆの−２０℃〜８０℃付近までの温度特性を著しく安定化する。ＳｒＯ：ＢａＯの配合比率が１：０．３未満ではτｆの安定性が乏しく、Ｑｆも低下し、また、１：２０を超えるにつれ急激にＱｆ、τｆ共に劣化する。その結果、ＢａＯとＣａＯの特定モル％範囲内での配合比率で得られた素子は、ＩＣ、Ｒ、Ｌ等の他の電子部品との組み合わせにおいて今までにない安定な部材として利用できる。しかしながら、ＢａＯとＣａＯの特定モル％範囲内での配合比率が１：０．３未満ではＱｆが低下し、また、１：２０を超えるにつれεｒが低下し、τｆの周波数の温度特性が大きく変化する。また、ＳｒＯ成分：ＢａＯ成分の比率が１：１．５６であって、ＳｒＯ成分：ＣａＯ成分の比率が１：１の配合比率において、周波数の変化に対して、Ｑｆおよびτｆの−２０℃〜８０℃付近での温度特性が著しく安定する。
【００２１】
Ｂｉ_２Ｏ_３は磁器の焼結温度を下げ、電気特性のτｆを正負の値に小さく制御する作用を有する。その含有量が０．２モル％未満ではτｆを小さくし正負の値に制御する効果が乏しくなる。また、１０モル％以上を超えると、磁器の焼成時にＢｉ成分の蒸発が大きく焼結性が著しく不安定になる。その結果Ｑｆが悪化しさらに高温負荷寿命特性が著しく劣化することになる。
【００２２】
Ｌｉ_２Ｏは、高周波領域におけるεｒを高く、τｆを小さく制御する作用を有している。その含有量が１モル％未満ではτｆを小さく制御する効果が乏しく、１３モル％を超えると、焼成時にＬｉ成分の蒸発が大きく磁器の気孔が増加し、εｒ、Ｑｆ、τｆが共に不安定となり、その結果、量産化に向けた工業製品として作製するのに好ましくない。
【００２３】
Ｌａ、Ｐｒ、Ｎｄ、Ｓｍの何れかの酸化物を表わすＬｎ_２Ｏ３は、磁器の結晶粒子径を小さく制御することができ、機械的強度を向上させ、そして、高周波領域におけるεｒ、Ｑｆを安定にしτｆを小さくする作用を有する。とくに、Ｌａはεｒの安定化に、また、ＮｄはＱｆの向上に、さらに、Ｓｍ、Ｐｒはτｆを小さくする作用を持つ。これらの成分を目的に応じて複合含有することにより、それぞれの効果を複合したより良い効果が期待できる。　その含有量が２モル％未満では電気特性の改善が望めなく、また、１５モル％を超えると、磁器の焼成温度が高くなり、他の成分との固溶性が悪化し、その結果、気孔の多い磁器になる。
【００２４】
上記基本成分からなる組成物は、その基本成分の合計量を１００重量部として、酸化物換算でＭＮｏ_２、Ｆｅ_２Ｏ_３、Ｃｏ_３Ｏ_４、Ｎｂ_２Ｏ_５、Ｔａ_２Ｏ_５の中の１種または２種以上を合計を０．１〜１０重量部を添加物として含有することができる。これにより、εｒ、Ｑｆが高く、τｆを正負の値に小さく制御することが可能になる。さらに磁器の機械的強度を高め、そして容量素子等の機能部品に用いた場合、高温高湿負荷寿命特性等を安定化することができる。個別の作用として、ＭＮｏ_２は、磁器の焼成温度幅を広げ、焼成時の還元を防止する。その結果、高周波領域で、Ｑｆの劣化を小さく抑える作用を有する。しかしながら、その含有量が０．１重量部未満では、焼成温度幅を広げる効果と、還元防止の効果も小さくなる。また、１０重量部を超えると逆に焼結性が悪化し、磁器の結晶粒子径が増大し気孔が大きくなり寿命特性等の劣化を伴うことになる。
【００２５】
Ｆｅ_２Ｏ_３は、磁器の焼成温度を下げＱｆを向上させる作用がある。しかし、０．１重量部未満では、焼成温度を下げる効果が小さくなり、また、１０重量部を超えると、他の主成分との反応が大きく、また、Ｑｆが約６０℃〜８０℃の高温では大きく劣化する。
【００２６】
Ｃｏ_３Ｏ_４は、磁器の焼成温度幅を広げると共に焼成時の還元防止し、Ｑｆ、τｆ等の電気特性を安定にし高温負荷寿命の劣化を抑える作用がある。しかしながら、その含有量が、０．１重量部未満では焼成温度幅を広げる効果が小さく、また、１０重量部を超えるとεｒの低下をきたしＱｆ、τｆの特性を悪化する。
【００２７】
Ｎｂ_２Ｏ_５は、高周波領域におけるεｒの温度変化に対するバラツキと機械的強度を安定にする作用を有する。　しかしながら、０．１重量部未満では機械的強度を安定にする効果が小さく、また、１０重量部を超えると磁器の結晶粒子径が大きくなり機械的強度が低下するため好ましくない。
【００２８】
Ｔａ_２Ｏ_５は、磁器の結晶粒子径を小さく機械的強度を高める作用があり、容量素子等の電子部品に利用した場合、軽薄化が可能となり小型化に対応できる。また、高周波領域においてＱｆを高め、τｆを小さく制御する。しかしながら、０．１重量部未満では磁器の結晶粒径を小さく、機械的強度の向上が小さい。また、１０重量部を超えるとεｒの低下を来たし好ましくない。これらの各々の添加物成分は、複合化して添加することにより、それぞれの特性が複合した効果が得られ、安定した諸特性が得られる。
【００２９】
本発明のマイクロ波誘電体磁器は、上記組成からなる混合物を直径が１〜１２ｍｍの範囲内の大きさの粒状あるいは塊状のペレット状に成型し、平均気孔率が２５％〜５０％のＡｌ_２Ｏ_３（アルミナ）、あるいはＡｌ_２Ｏ_３−ＺｒＳｉＯ_４（アルミナ−ジルコン）、ＺｒＯ_２（ジルコニア）、Ａｌ_２Ｏ_３−ＳｉＯ_２（ムライト）の中の１種または２種以上の複合体の通気性多孔質焼結体容器を用い温度９００℃〜１２００℃の範囲内で仮焼し、得られた仮焼物を、０．３μｍ〜２．０μｍの平均粒子径に粉砕調整して仮焼粉末を調製し、その仮焼粉末に有機バインダーを添加し成型し、前記通気性多孔質焼結体容器を用い１２００℃〜１４００℃の温度で焼成することによって得られる。仮焼時のペレットへの温度差を最小限度に抑え、ＢｉおよびＬｉ成分の蒸気圧分を一定にし、磁器組成物中の蒸発成分のガスをコントロールすることができ、量産化におけるバラツキを抑え電気特性としてεｒが１４５以上、Ｑｆが１７００以上およびτｆをゼロから正負に自由に制御可能にした。
【００３０】
上記の通気性多孔質焼結体容器を用いることにより、組成物原料と仮焼温度（９００℃〜１２００℃）での容器との反応現象が起きにくく、また、焼結体容器であるため仮焼後の取り出し作業工程で容器成分である不純物の混入が無く、通気性多孔質焼結体で構成されているので容器の重量が軽く、通気孔があるので蒸発成分の透過性が一定になり、均質性に優れた仮焼粉末を得ることができる。
【００３１】
仮焼温度である９００℃〜１２００℃は、本発明組成物の安定性、電気特性、および機械的特性を得るために必要な温度域であり、９００℃未満では均質性に富んだ仮焼粉末が得られず、また、１２００℃を超えると固相反応が進みペレット状の仮焼物が硬く粉砕および成型以降の量産工程で工数がかかると共に電気特性、機械的特性が著しく悪化する。
【００３２】
仮焼粉末の平均粒子径を０．３μｍ〜２．０μｍの範囲内に粉砕調整することによって、その後の有機バインダーを添加し、成型する工程において成型時の亀裂、ひずみ、割れの発生を防ぎ用途に応じた形状の複雑成型を可能とし、焼成後の磁器の機械的強度さらには電気特性等を安定にする効果が得られる。しかし、０．３μｍ未満では成型割れが起き易く好ましくない。また、２．０μｍを超えるとポアが発生し易いため好ましくない。
【００３３】
その後、有機バインダーを適量添加、成型し、前記通気性多孔質焼結体容器を用いて、１２００℃〜１４００℃の範囲内で焼成することによって、蒸発成分であるＢｉおよびＬｉ成分の蒸気圧を一定にするとともに、著しく安定した諸特性を有するマイクロ波誘電体磁器が得られる。焼成温度が１２００℃未満の場合は均質性において欠陥を生じ、１４００℃を超えると機械的強度が著しく低下し他の諸特性も悪化する。
【００３４】
【発明の実施の形態】
以下、本発明の実施の形態を添付の図と表に示す実施例を基に説明する。
【００３５】
表１〜２は本発明の基本組成成分と諸特性の関係を示し、表３〜４は本発明の添加物および添加量と諸特性の関係を示し、表５〜６は本発明の通気性多孔質焼結体容器の気孔率と諸特性の関係を示す。
【００３６】
９９％以上の高純度の、ＴｉＯ_２、ＳｒＣＯ_３、ＢａＣＯ_３、ＣａＣＯ_３、Ｂｉ_２Ｏ_３、Ｌｉ_２ＣＯ_３、Ｌａ_２ＣＯ_３、Ｐｒ_６Ｏ_１１、Ｎｄ_２Ｏ_３、Ｓｍ_２Ｏ_３、ＭｎＣＯ_３、Ｆｅ_２Ｏ_３、Ｃｏ_３Ｏ_４、Ｎｂ_２Ｏ_５、Ｔａ_２Ｏ_５の各種原料を用い、表１〜４の各配合比率になるように秤量した。純水あるいはメタノールを用い、３００ＣＣのウレタン内張りポットミルおよび高純度でφ５ｍｍ〜φ１２ｍｍの球状を有するＺｒＯ_２ボールを用い２４時間混合し、１２０℃で乾燥させる。乾燥粉末をアルミナ製乳鉢で粉砕し、ＰＶＡ２％水溶液を８重量部添加し粒状、塊状のペレットを作製した。
【００３７】
尚、原料として、炭酸カルシウム、炭酸ストロンチウム、炭酸マンガンを用いたが前記金属の酸化物に限らず、例えば、炭酸塩、シュウ酸塩、硝酸塩、アルコキシドなどにより得られた粉末で、焼成後に目的の酸化物が得られるものであれば、同等の効果を期待することができる。
【００３８】
このペレットを通気性多孔質焼結体容器を用い仮焼物の作製を行った。
【００３９】
図１は、仮焼物の作製に使用する通気性多孔質焼結体容器の一例を示す。同図において、１は長方形の形状を有している通気性多孔質焼結体容器、２は容器の材質であるジルコニア成分、３は平均気孔率が約３５％〜４０％の通気孔を有するもので、空気、ガス等の気体源の通過を容易にし仮焼さらには本焼成に用いられるものである。しかし、上記容器であっても焼結性が不足し吸水性のある容器では、仮焼粉末さらには本焼成時に成型物のガスや粉末が容器内に残り安定した効果が得られない。
【００４０】
この通気性多孔質焼結体容器として次の方法で作製した。まず純度９９％で粒子径１００μｍのジルコニア原料粉末を用い、添加物として外割で酸化イットリウム２重量部さらに酸化珪素２重量部の成分比率の各原料を用いウレタン製ポットミル中に投入し、ウレタンボ−ルと水、さらに水ガラス少量を加え３時間湿式混合を行い均一に混合した。この混合物を容器の形状を有した石膏型に流し込み水分を除去した後、型より取り出し十分に乾燥させた。この成型体を高純度のアルミナ質平板上に置きカンタルヒ−タ−を用いた電気炉において焼成温度１５５０℃約２時間保持でジルコニア成分材質の通気性多孔質焼結体容器を得た。
本実施例では１００μｍのジルコニア成分材質の容器について説明したが他の成分材質および粒子径の大きな原料粉末を用いても同様な効果が得られる。
【００４１】
仮焼物は粒状、塊状のペレットを図１に示す通気性多孔質焼結体容器を用い、仮焼温度８００℃〜１２２０℃で１時間保持した。
【００４２】
そして、この仮焼物を再度乳鉢で粉砕し上記ポットミルを用い粉砕混合し、粉砕粒子径０．２μｍ〜４．０μｍになるように作製した。その後、分別された粉末原料にＰＶＡ５％水溶液を４重量部添加し、乳鉢で均一になるよう攪拌し、その後＃３２０メッシュの篩いを用い整粒し、プレス圧１ｔｏｎ／ｃｍ^２で直径１２ｍｍ、厚み７ｍｍの円盤状に成型した。また機械的強度測定用試料として、厚み３．７ｍｍ、幅５ｍｍ、長さ２５ｍｍの成型体も同時に作製した。
【００４３】
その後、前記図１に示す容器を用い、大気中にて焼成温度１１８０℃〜１４２０℃て約２時間保持で焼成しマイクロ波誘電体磁器を得た。得られた磁器の上下面を＃２００のダイヤモンドホイールを用い研磨しφ１０ｍｍ×５ｍｍｔの測定用素子に加工した後、Ｈａｋｋｉ−Ｃｏｌｅｍａｎ法によりヒューレットパッカード社のネットワークアナライザーを用い測定周波数１〜７ＧＨｚ、さらに恒温槽を用い、εｒ、Ｑｆ、およびτｆと温度に対する変化特性を調べた（表５〜６の緒特性と対応）。機械的強度測定は島津製作所製抗折試験機を用いた。
【００４４】
また、容量素子として利用するため、表３の試料、Ｎｏ２２の誘電体磁器を厚み１２０μｍに研磨し、その後Ａｇ−Ｐｔ電極を形成後、（約１０ｐＦの容量素子を作製する。）ヒューレットパッカード社のＬＣＲメーターを用い周波数１ＫＨｚ〜０．１ＧＨｚの範囲内に変化させ、Ｃ（容量値）、Ｑ（無負荷損失係数）、Ｃ−ＴＣ（容量値の温度特性）の温度に対する特性を調べた。
【００４５】
組成成分を示す表１と、それに対応しての特性結果が表２に示されている。これらの表において、試料Ｎｏの欄に、無印番号のものが実施例を示し、＊マークを付したものが範囲外の例である。
【００４６】
【表１】

【表２】

試料Ｎｏ１は、ＴｉＯ_２が４４モル％であって、本発明の特定範囲外であって、他の成分のＳｒＯとＢａＯとＳｒＯとＣａＯはいずれも特定範囲内ではあり、焼成温度は最適温度である１３００℃で焼成したが、その磁器は吸水性の有る焼結状態で電気特性および機械的強度も低いものであった。
【００４７】
Ｎｏ２〜４は基本組成の成分量が特定範囲外であり、また、ＳｒＯとＣａＯの配合比率も範囲外であって、εｒ、Ｑｆが低く、高温負荷寿命特性において著しい劣化の傾向がみられた。
【００４８】
Ｎｏ５〜６およびＮｏ８〜１４の実施例、とくに、Ｎｏ８の試料は、配合原料を仮焼後の粉砕粒子径を０．５μｍ〜０．８μｍに調整し、１３００℃で焼成した。焼結体は表面が緻密で３μｍ〜４μｍの均一な結晶粒子径を有していた。また、機械的強度は２０５ＭＰａと高く、電気特性はεｒが１５１、Ｑｆが１７５０、τｆが０ｐｐｍ／℃と非常に優秀であり、高温負荷寿命特性においても劣化の現象は認められなかった。また、Ｎｏ１２は、仮焼後の粉砕粒子径を０．５μｍ〜０．８μｍに調整し、１３２０℃で焼成した。焼結状態も良好で機械的強度は２００ＭＰａと高く、電気特性はεｒは１６３と高く、Ｑｆは１８００、τｆは−７ｐｐｍ／℃と負に小さく制御可能であった。また、結晶粒子径は３．５μｍ〜４．５μｍであった。
【００４９】
表３は、本発明の基本組成に対する添加物および添加量を示し、表４は諸特性を示す。表１，２と同様に、無印番号のものが実施例を示し、＊マークを付したものが範囲外の例である。
【００５０】
【表３】

【表４】

試料Ｎｏ８は、表１と２に示す添加物が添加されていない基本組成を有する本発明の実施例を示すもので、添加物成分配合の効果を示すために同表に挙げている。試料Ｎｏ１６〜２２は本発明に規定する範囲内で添加物を添加したもので、それぞれ、１２７０℃〜１３００℃で焼成した磁器で平均結晶粒子径は約０．８μｍ〜３．５μｍと均一であった。添加物が添加されていない試料Ｎｏ８と対比して、機械的強度は向上している。また電気特性のεｒは安定し、Ｑｆは著しく向上している。そしてτｆは正負に自由に小さく制御することが可能で添加物の効果が認められた。
【００５１】
図２は、添加物を添加した試料Ｎｏ２２と添加物を添加していない試料Ｎｏ８との温度と周波数の変化に対するＱｆ、τｆの関係を示す。同図により明らかなように、試料Ｎｏ２２は試料Ｎｏ８と対比して、−２０℃〜８０℃の温度範囲にわたって周波数が３ＧＨｚおよび７ＧＨｚにおいてもＱｆおよびτｆの特性値の変化は小さく安定していることが認められる。
【００５２】
また、図３は、試料Ｎｏ２２を用い容量素子として作製した試料の温度と周波数の変化に対するＣ（容量値）、Ｑ（無負荷損失係数）、Ｃ−ＴＣ（容量値の温度特性）の関係を示す。同図に示すように、試料Ｎｏ２２は、１ＫＨｚ〜０．１ＧＨｚの周波数の変化に対してＣ、Ｑ、およびＣ−ＴＣの変化は小さく、温度−２０℃〜８０℃の変化に対しても著しく安定した特性を示す。試料Ｎｏ２３、２４，２７は、添加物が範囲外でいずれも特性的には悪いものであった。
【００５３】
試料Ｎｏ２５、２６は、それぞれ、基本組成成分に、添加物としてＭＮｏ_２を０．２、Ｆｅ_２Ｏ_３を０．２、Ｃｏ_３Ｏ_４を０．５、Ｎｂ_２Ｏ_５を２．０、Ｔａ_２Ｏ_５を１．５重量部添加し、及び、ＭＮｏ_２を０．１、Ｃｏ_３Ｏ_４を３．０、Ｎｂ_２Ｏ_５を２．０重量部添加し、１３２０℃で焼成した。焼成磁器は平均結晶粒子径が約１．３μｍ〜２．０μｍと小さく均一で、表４に示すように、機械的強度、電気特性εｒは高く、Ｑｆとτｆは負に小さく制御でき著しく優れている。そして寿命特性として温度８０℃、湿度８５％、５００時間のテスト後も、ほとんど変化は認められずマイクロ波誘電体磁器としてその優秀性が認められた。
【００５４】
表５〜６は、本発明の磁器組成物の仮焼、焼成に使用する通気性多孔質焼結体容器と得られた磁器組成物の特性との関係を示す。これらの表において、焼成に使用する通気性多孔質焼結体容器が本発明の特定要件を満たす場合を試料Ｎｏに＊マークを付していないＮｏによって示し、＊を付した試料Ｎｏは、本発明の特定要件を満たしていない例を示している。具体的には、表１〜２に示す基本組成の代表例として試料Ｎｏ８の組成物を用い、本発明の通気性多孔質焼結体容器の気孔率と諸特性の関係で、仮焼用ペレット状成型体の大きさおよび仮焼温度と電気特性の関係を調べた。
【００５５】
【表５】

【表６】

表５〜６より明らかなように、平均気孔率が特定範囲外の場合には、他の条件の如何に拘わらず得られた磁器は焼結状態のバラツキが大きく均一性に乏しい。
【００５６】
本発明の実施例を示す試料Ｎｏ３１〜３５は、ペレット形状、仮焼温度、仮焼後の粉砕粒子径さらには焼成温度を特定範囲内で変化させた例であり、いずれも良好な磁器を得ることができ機械的強度は１９０ＭＰａ〜２０５ＭＰａと高く電気特性も著しく安定した良好な値を示している。さらに、同じく試料Ｎｏ４２、４３は、表３〜４に示す試料Ｎｏ２５の組成物を用いた例で、いずれも良好な電気特性を示す。
【００５７】
これに対して、平均気孔率が規定範囲外の１０％〜２３％である通気性多孔質焼結体容器を使用した試料Ｎｏ２８は、他の条件が満たされてはいても得られた磁器は焼結状態のバラツキが大きく均一性に乏しく量産化には不向きであった。
【００５８】
また、試料Ｎｏ２９は平均気孔率が規定範囲外の５５％〜７０％と大きい容器によって得られた磁器の機械的強度は低く、電気特性のεｒは著しく低下の傾向を示した。試料Ｎｏ３０は仮焼用のペレット形状が小さなものではεｒが低下の傾向にあった。これはＢｉ、Ｌｉ成分の蒸発が不均一になったためと考えられる。また、Ｎｏ３６〜４１は、表より明らかなようにいずれかの条件が範囲外であるため、特性的には悪いものであった。
【００５９】
【発明の効果】
以上説明したように、本発明のＢｉ、Ｌｉ成分を含有する基本組成成分のマイクロ波誘電体磁器組成物は、それぞれの組成成分を特定範囲内で制御することによって、高周波領域におけるεｒが１４５以上と高く、Ｑｆが１７００以上と大きく、τｆをゼロから正負に自由に制御できる効果を有する。
【００６０】
また、基本組成成分に、特定の添加物を添加することによって、さらに、εｒ、Ｑｆが高く、τｆをゼロから正負に自由に制御でき安定化できる。
【００６１】
さらに、その製造過程における仮焼、焼成に際して、平均気孔率が２５％〜５０％の範囲内にあるアルミナもしくはアルミナ−ジルコン、ジルコニア、ムライト成分材質の通気性多孔質焼結体容器を用いることによってＢｉ、Ｌｉ成分の蒸発を最小限に抑え、良好な電気特性を有する均一なマイクロ波誘電体磁器を得ることができる。
【００６２】
そして、本発明のＢｉ、Ｌｉ成分を含有する基本組成成分のマイクロ波誘電体磁器組成物は、寿命特性に優れているので多層回路基板、とくに、高周波領域において使用される共振器材料、フィルター材料、アイソレータ部品さらには容量素子材等として利用できる。
【００６３】
また、機械的強度が高いので部品として、その製品形状を小さく設計でき、さらに軽薄化になると共に著しく厳しい環境下の使用状況にあっても、高い信頼性の部品を製作することが可能となり、今後の情報通信分野等の産業的分野での利用価値は大きい。
【図面の簡単な説明】
【図１】本発明のマイクロ波誘電体磁器の仮焼、焼成に使用する通気性多孔質焼結体容器を示す。
【図２】本発明のマイクロ波誘電体磁器の温度と周波数の変化に対するＱｆ、τｆの関係を示す。
【図３】温度と周波数の変化に対するＣ、Ｑ、Ｃ−ＴＣの関係を示す。
【符号の説明】
１　通気性多孔質焼結体容器
２　ジルコニア成分
３　通気孔[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a microwave dielectric, in particular, various resonator materials, filter materials, MIC dielectric substrate materials, antenna materials, multilayer chip capacitor materials, and isolator materials used in high frequency regions such as microwaves and millimeter waves. TECHNICAL FIELD The present invention relates to a microwave dielectric porcelain composition that can be used for a capacitance element or the like of a mobile phone component such as a cellular phone, and a method for manufacturing the porcelain.
[0002]
[Prior art]
2. Description of the Related Art In recent years, mobile communication systems such as a mobile phone, a mobile phone, and a PHS, and GPS have rapidly spread due to advances in communication technology. For this reason, the frequency band used for communication devices has been expanded, and the use in the microwave band has become active.
[0003]
In circuits used in the microwave band, components such as a cavity resonator and an antenna have been used. However, since these components have the same size as the wavelength of microwaves, it has not been possible to reduce the size of components that can be applied to automobile telephones, mobile telephones, small GPS devices, and the like.
[0004]
On the other hand, by using a dielectric resonator in a frequency stabilizing circuit of a microwave filter or a transmitter in recent years, circuit components have been reduced in size and are becoming popular. The dielectric material used for such a dielectric resonator has a high dielectric constant (εr) in a used frequency band, and a product of a no-load quality factor (Q) and a resonance frequency (f0) in a microwave band (f0). Q × f0 (hereinafter abbreviated as Qf) is high, and the temperature coefficient of resonance frequency (τf: ppm / ° C.) can be freely controlled from positive to negative centering around zero. It is particularly important that the capacitance element material used in the method (1) has εr of 140 or more, Qf of 1700 GHz or more, and τf arbitrarily controllable.
[0005]
Further, recently used substrates (capacitance element materials) have been further reduced in thickness, and the thickness of the substrates has been reduced to 0.05 mmt. However, the capacitance value is determined by the shape, size, number, etc. of the pores present in the material. Therefore, there is a problem that the capacitor and the short-circuit product may occur, and it is indispensable to control the pores in the material.
[0006]
As such a microwave dielectric porcelain composition, for example, JP-A-5-212007 discloses a composition Li ₂ O-CaO-Ln ₂ O ₃ -TiO ₂ Wherein Ln is Nd or Sm. As the characteristics of the disclosed composition, εr is 141, Qf is 1215 GHz, τf is +25 ppm / ° C., and τf is controlled to be as low as about 100 when τf is controlled.
[0007]
JP-A-6-243722 discloses that the composition is Li ₂ O-CaO-Sm ₂ O ₃ -Ln ₂ O ₃ -TiO ₂ And a microwave dielectric porcelain composition wherein Ln is Nd, La or Pr is disclosed, and as its characteristics, those having εr of 130, Qf of 1300 GHz, and τf of +30 ppm / ° C. ing.
[0008]
Furthermore, Japanese Patent Application Laid-Open No. 9-208303 discloses that BaO-SrO-Sm ₂ O ₃ -Bi ₂ O ₃ -La ₂ O ₃ -TiO ₂ A microwave dielectric porcelain composition of the type is disclosed, and its characteristics indicate that εr is 140, Qf is 1650 GHz, and τf is +37 ppm / ° C.
[0009]
[Problems to be solved by the invention]
However, the composition disclosed in JP-A-5-212007 has a high εr of 141 but a low Qf of 1215, and the τf is not fully controlled within ± 15 ppm / ° C. Further, in the control in which τf is within ± 15 ppm / ° C., εr stays at a low value of around 100.
[0010]
Further, the composition disclosed in JP-A-6-243722 has a Sm ₂ O ₃ Is Nd ₂ O3, La ₂ O ₃ , Pr ₆ O ₁₁ Εr is kept at 130 by substituting any one of the above, but τf is as large as +30 ppm / ° C., and when τf is controlled at ± 10 ppm / ° C., εr becomes 125 and Qf also decreases. There's a problem.
[0011]
Further, the composition disclosed in Japanese Patent Application Laid-Open No. 9-208303 shows high characteristics with εr of 140 and Qf of 1650, but has a problem that τf is as large as +37 ppm / ° C.
[0012]
As described above, all of the above conventional technologies have the required characteristics that εr ≧ 140, Qf ≧ 1700, and τf ≦ 15 ppm / ° C., which are required for recent miniaturization, and that they can be controlled to an arbitrary value, positive or negative. At the same time, satisfactory materials could not be obtained.
[0013]
The most significant factor was that the composition ratio of the Bi and Li components contained therein was greatly varied due to evaporation during high-temperature sintering and was not stable in the mass production process.
[0014]
The problem to be solved by the present invention is the required characteristics for downsizing the microwave dielectric, that is, the relative dielectric constants εr and Qf in a high frequency region such as a microwave and a millimeter wave, and furthermore, a resonance frequency. An object of the present invention is to provide a microwave dielectric ceramic which can stably control the temperature coefficient τf and has a small characteristic variation in mass production and is suitable for mass production.
[0015]
[Means for Solving the Problems]
In the microwave dielectric ceramic composition of the present invention, the basic composition component is aTiO2 in terms of oxide. ₂ -BSrO-cBaO-dCaO-eBi ₂ O ₃ -FLi ₂ O-gLn ₂ O ₃ (Ln is one or more selected from lanthanide group elements of La, Pr, Nd and Sm),
When a + b + c + d + e + f + g = 100 mol%, each of a to g is mol%, and 45 ≦ a ≦ 71, 0.4 ≦ b ≦ 6, 0.2 ≦ c ≦ 18, 0.2 ≦ d ≦ 18. , 0.2 ≦ e ≦ 10, 1 ≦ f ≦ 13, 2 ≦ g ≦ 15,
and,
Each mixing ratio of bSrO and cBaO, bSrO and dCaO is
b: c is 1: 0.3 to 1:20 and
b: d is 1: 0.3 to 1:20
It is characterized by being.
[0016]
TiO ₂ Has a function as a basic component as a microwave dielectric porcelain. If its content is less than 45 mol%, εr will decrease and the desired high εr cannot be obtained. On the other hand, if it exceeds 71 mol%, τf is unduly large, and Qf is undesirably low, not more than 1000.
[0017]
SrO has stable electric characteristics in a high frequency range. If the content is less than 0.4 mol%, εr decreases, and the effect of freely controlling τf from zero to positive or negative becomes poor. On the other hand, if it exceeds 6 mol%, εr increases, but Qf becomes 1000 or less, and it becomes difficult to control τf to a target value.
[0018]
BaO has the effect of reducing the crystal grain size of the porcelain and controlling the value of εr. It is possible to obtain desired dielectric properties within a predetermined range. If the content is less than 0.2 mol%, the effect of controlling the crystal grain size of the porcelain to be small is poor, and as a result, when fabricated in a capacitor or the like, Q deteriorates during the high-temperature load life. On the other hand, if it exceeds 18 mol%, the crystal grain size grows remarkably, and the mechanical strength is lowered, so that it is no longer possible to meet the demand for lighter electronic components. Further, both εr and Qf become unstable during the high temperature load life.
[0019]
The CaO component has the effect of reducing the crystal grain size of the porcelain, thereby increasing the mechanical strength and stabilizing it. Further, it has the effect of increasing Qf in the high frequency region. By changing the mixing ratio with the SrO component, C (capacitance value) and Q (nothing) with respect to the relationship between the temperature and frequency of the capacitive element in the frequency region of 1 KHz to 0.1 GHz. It is possible to remarkably stabilize the temperature characteristics of changes in the load loss coefficient) and the C-TC (temperature characteristics of the capacitance value), particularly the temperature characteristics in the vicinity of 20 ° C to 80 ° C. If the content of CaO is less than 0.2 mol%, the effect of reducing the crystal grain size of the porcelain is poor, and as a result, the mechanical strength is not improved, and the Qf in the high frequency region is further reduced. Then, the temperature characteristic of τf becomes unstable. On the other hand, if it exceeds 18 mol%, εr will decrease, and it will be difficult to control τf to a target value.
[0020]
The change in the mixing ratio of the SrO component, BaO, and CaO within a specific mol% range is from 1 to 7 GHz band in a high frequency range. Remarkably stabilizes. If the mixing ratio of SrO: BaO is less than 1: 0.3, the stability of τf is poor and Qf decreases, and as it exceeds 1:20, both Qf and τf rapidly deteriorate. As a result, an element obtained with a mixing ratio of BaO and CaO within a specific mol% range can be used as an unprecedented stable member in combination with other electronic components such as IC, R, and L. However, when the compounding ratio of BaO and CaO in the specific mol% range is less than 1: 0.3, Qf decreases, and as it exceeds 1:20, εr decreases, and the temperature characteristic of the frequency of τf greatly changes. I do. Further, when the ratio of the SrO component: BaO component is 1: 1.56 and the ratio of the SrO component: CaO component is 1: 1, the Qf and τf of −20 ° C. Temperature characteristics around 80 ° C. are remarkably stable.
[0021]
Bi ₂ O ₃ Has the effect of lowering the sintering temperature of the porcelain and controlling the electrical characteristic τf to a small positive or negative value. If the content is less than 0.2 mol%, the effect of reducing τf and controlling it to a positive or negative value becomes poor. On the other hand, if the content exceeds 10 mol% or more, the evaporation of the Bi component during firing of the porcelain becomes large, and the sinterability becomes extremely unstable. As a result, Qf is deteriorated, and the high temperature load life characteristic is significantly deteriorated.
[0022]
Li ₂ O has the effect of controlling εr to be high and τf to be small in the high frequency region. If the content is less than 1 mol%, the effect of controlling τf to be small is poor. If it exceeds 13 mol%, the Li component evaporates greatly during firing and the porosity of the porcelain increases. As a result, it is not preferable to manufacture as an industrial product for mass production.
[0023]
Ln representing an oxide of any of La, Pr, Nd and Sm ₂ O3 has the effect of controlling the crystal grain size of the porcelain to be small, improving the mechanical strength, and stabilizing εr and Qf in the high frequency region and reducing τf. In particular, La has the effect of stabilizing εr, Nd has the effect of improving Qf, and Sm and Pr have the effect of reducing τf. By combining these components according to the purpose, a better effect combining the respective effects can be expected. If the content is less than 2 mol%, improvement in electrical properties cannot be expected, and if it exceeds 15 mol%, the sintering temperature of the porcelain increases, and the solid solubility with other components deteriorates. It becomes a lot of porcelain.
[0024]
The composition consisting of the above basic components is represented by MNo in terms of oxide, with the total amount of the basic components being 100 parts by weight. ₂ , Fe ₂ O ₃ , Co ₃ O ₄ , Nb ₂ O ₅ , Ta ₂ O ₅ Or a total of 0.1 to 10 parts by weight as an additive. This makes it possible to control εr and Qf to be high and τf to be small to positive and negative values. Further, when the mechanical strength of the porcelain is increased, and when the porcelain is used for a functional component such as a capacitance element, it is possible to stabilize the high-temperature / high-humidity load life characteristics and the like. As an individual action, MNo ₂ Extends the firing temperature range of the porcelain and prevents reduction during firing. As a result, it has an effect of suppressing the deterioration of Qf in a high frequency region. However, when the content is less than 0.1 part by weight, the effect of widening the firing temperature range and the effect of preventing reduction are reduced. On the other hand, if the content exceeds 10 parts by weight, the sinterability deteriorates, the crystal grain size of the porcelain increases, the pores become large, and the life characteristics and the like deteriorate.
[0025]
Fe ₂ O ₃ Has the effect of lowering the firing temperature of porcelain and improving Qf. However, if the amount is less than 0.1 part by weight, the effect of lowering the sintering temperature is small. If the amount exceeds 10 parts by weight, the reaction with other main components is large, and Qf is about 60 ° C. to 80 ° C. Will greatly deteriorate.
[0026]
Co ₃ O ₄ Has the effect of widening the firing temperature range of the porcelain, preventing reduction during firing, stabilizing the electrical characteristics such as Qf and τf, and suppressing the deterioration of the high-temperature load life. However, if the content is less than 0.1 part by weight, the effect of widening the firing temperature range is small, and if the content exceeds 10 parts by weight, εr is reduced and the characteristics of Qf and τf are deteriorated.
[0027]
Nb ₂ O ₅ Has an effect of stabilizing the variation of εr with respect to the temperature change and the mechanical strength in the high frequency region. However, if the amount is less than 0.1 part by weight, the effect of stabilizing the mechanical strength is small, and if it exceeds 10 parts by weight, the crystal grain size of the porcelain becomes large and the mechanical strength decreases, which is not preferable.
[0028]
Ta ₂ O ₅ Has the effect of reducing the crystal grain size of the porcelain and increasing the mechanical strength. When used in electronic components such as capacitance elements, it can be made lighter and thinner and can be made smaller. Further, Qf is controlled to be high and τf is controlled to be small in a high frequency region. However, when the amount is less than 0.1 part by weight, the crystal grain size of the porcelain is small, and the improvement in mechanical strength is small. On the other hand, if it exceeds 10 parts by weight, εr will decrease, which is not preferable. By compounding and adding each of these additive components, the effect of combining the respective characteristics can be obtained, and stable various characteristics can be obtained.
[0029]
The microwave dielectric porcelain of the present invention is obtained by molding a mixture having the above composition into granular or massive pellets having a diameter in the range of 1 to 12 mm, and having an average porosity of 25% to 50%. ₂ O ₃ (Alumina) or Al ₂ O ₃ -ZrSiO ₄ (Alumina-zircon), ZrO ₂ (Zirconia), Al ₂ O ₃ -SiO ₂ (Mullite) and calcined in a temperature range of 900 ° C. to 1200 ° C. using a gas-permeable porous sintered body container of one or more composites of (Mullite), and the obtained calcined product was 0.3 μm A calcined powder is prepared by pulverizing and adjusting to an average particle size of ~ 2.0 µm, an organic binder is added to the calcined powder, and the calcined powder is molded using the gas-permeable porous sintered body container at 1200 ° C to 1400 ° C. It is obtained by firing at a temperature. The temperature difference between the pellets during calcination is kept to a minimum, the vapor pressure of Bi and Li components is kept constant, the gas of the evaporation components in the porcelain composition can be controlled, and the variation in mass production can be suppressed. As characteristics, εr is 145 or more, Qf is 1700 or more, and τf can be freely controlled from zero to positive or negative.
[0030]
By using the air-permeable porous sintered body container, a reaction phenomenon between the composition raw material and the container at the calcination temperature (900 ° C. to 1200 ° C.) hardly occurs. During the removal process after baking, there is no mixing of impurities that are container components, and since it is made of an air-permeable porous sintered body, the weight of the container is light, and the presence of vent holes keeps the permeability of evaporation components constant. Thus, a calcined powder having excellent homogeneity can be obtained.
[0031]
The calcining temperature of 900 ° C. to 1200 ° C. is a temperature range necessary for obtaining the stability, electric properties, and mechanical properties of the composition of the present invention. If the temperature exceeds 1200 ° C., the solid phase reaction proceeds, and the calcined pellets become hard, which takes a lot of man-hours in the mass production process after pulverization and molding, and significantly deteriorates the electrical and mechanical properties.
[0032]
By adjusting the average particle diameter of the calcined powder to a range of 0.3 μm to 2.0 μm, a subsequent organic binder is added to prevent cracks, strains and cracks during molding in the molding step. In this case, it is possible to obtain an effect of stabilizing the mechanical strength of the porcelain after firing and further stabilizing the electrical characteristics and the like. However, when the thickness is less than 0.3 μm, molding cracks easily occur, which is not preferable. On the other hand, if the thickness exceeds 2.0 μm, pores are easily generated, which is not preferable.
[0033]
Thereafter, an appropriate amount of an organic binder is added, molded, and baked in the range of 1200 ° C. to 1400 ° C. using the gas-permeable porous sintered body container, so that the vapor pressures of Bi and Li components as evaporation components are reduced. A microwave dielectric porcelain having constant and remarkably stable characteristics can be obtained. When the firing temperature is lower than 1200 ° C., defects occur in homogeneity. When the firing temperature is higher than 1400 ° C., mechanical strength is remarkably reduced and other properties are also deteriorated.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples shown in the attached drawings and tables.
[0035]
Tables 1 and 2 show the relationship between the basic composition components and various properties of the present invention, Tables 3 and 4 show the relationship between the additives and the amounts added and various properties of the present invention, and Tables 5 and 6 show the air permeability of the present invention. The relationship between the porosity of a porous sintered body container and various characteristics is shown.
[0036]
High purity 99% or more TiO ₂ , SrCO ₃ , BaCO ₃ , CaCO ₃ , Bi ₂ O ₃ , Li ₂ CO ₃ , La ₂ CO ₃ , Pr ₆ O ₁₁ , Nd ₂ O ₃ , Sm ₂ O ₃ , MnCO ₃ , Fe ₂ O ₃ , Co ₃ O ₄ , Nb ₂ O ₅ , Ta ₂ O ₅ Were weighed so that the respective mixing ratios shown in Tables 1 to 4 were obtained. Using pure water or methanol, a 300 cc urethane-lined pot mill and high-purity ZrO having a spherical shape of φ5 mm to φ12 mm ₂ Mix for 24 hours using a bowl and dry at 120 ° C. The dried powder was pulverized in an alumina mortar, and 8 parts by weight of a 2% aqueous solution of PVA was added to produce granular and massive pellets.
[0037]
In addition, as a raw material, calcium carbonate, strontium carbonate, and manganese carbonate were used, but not limited to the oxides of the above-mentioned metals, for example, powders obtained from carbonates, oxalates, nitrates, alkoxides, etc. An equivalent effect can be expected as long as an oxide can be obtained.
[0038]
The calcined product was produced from the pellets using a gas-permeable porous sintered body container.
[0039]
FIG. 1 shows an example of a gas-permeable porous sintered body container used for producing a calcined product. In the figure, 1 is a gas-permeable porous sintered container having a rectangular shape, 2 is a zirconia component which is a material of the container, 3 is a gas-pore having an average porosity of about 35% to 40%. It facilitates the passage of a gas source such as air or gas, and is used for calcining and also for final firing. However, even in the above-mentioned container, in a container having insufficient sinterability and having water absorption, the calcined powder and the gas or powder of the molded product at the time of main firing remain in the container, and a stable effect cannot be obtained.
[0040]
This air-permeable porous sintered body container was produced by the following method. First, a zirconia raw material powder having a purity of 99% and a particle diameter of 100 μm was used, and the raw materials having a component ratio of 2 parts by weight of yttrium oxide and 2 parts by weight of silicon oxide were added as additives to a urethane pot mill. And water, and a small amount of water glass were added, and the mixture was wet-mixed for 3 hours to uniformly mix. The mixture was poured into a gypsum mold having the shape of a container to remove water, and then removed from the mold and dried sufficiently. This molded body was placed on a high-purity alumina flat plate and kept at a firing temperature of 1550 ° C. for about 2 hours in an electric furnace using a kanthal heater to obtain a gas-permeable porous sintered body container made of a zirconia component material.
In this embodiment, a container made of a 100 μm zirconia component material has been described. However, similar effects can be obtained by using other component materials and a raw material powder having a large particle diameter.
[0041]
As the calcined product, granular and massive pellets were held at a calcination temperature of 800 ° C. to 1220 ° C. for 1 hour using a gas-permeable porous sintered container shown in FIG.
[0042]
Then, the calcined product was pulverized again in a mortar and pulverized and mixed using the above-mentioned pot mill to produce a pulverized particle diameter of 0.2 μm to 4.0 μm. Thereafter, 4 parts by weight of a 5% aqueous solution of PVA was added to the separated powdery raw material, and the mixture was stirred in a mortar so as to be uniform, and then sized using a # 320 mesh sieve. ² To form a disk having a diameter of 12 mm and a thickness of 7 mm. As a sample for measuring mechanical strength, a molded product having a thickness of 3.7 mm, a width of 5 mm, and a length of 25 mm was simultaneously produced.
[0043]
Thereafter, using the container shown in FIG. 1, firing was performed in the atmosphere at a firing temperature of 1180 ° C. to 1420 ° C. for about 2 hours to obtain a microwave dielectric porcelain. The upper and lower surfaces of the obtained porcelain were polished using a # 200 diamond wheel and processed into a measuring element of φ10 mm × 5 mmt. Using a tank, the change characteristics with respect to εr, Qf, τf and temperature were examined (corresponding to the characteristics shown in Tables 5 and 6). Mechanical strength was measured using a bending tester manufactured by Shimadzu Corporation.
[0044]
In addition, in order to use the capacitor as a capacitor, the dielectric ceramic of the sample No. 22 shown in Table 3 was polished to a thickness of 120 μm, and then an Ag-Pt electrode was formed. Then, a capacitor of about 10 pF was manufactured. The frequency was changed within the range of 1 KHz to 0.1 GHz using an LCR meter, and the characteristics of C (capacitance value), Q (no-load loss coefficient), and C-TC (temperature characteristics of capacitance value) with respect to temperature were examined.
[0045]
Table 1 showing the composition components and the corresponding characteristic results are shown in Table 2. In these tables, in the sample No. column, those with no mark indicate examples, and those marked with * are examples outside the range.
[0046]
[Table 1]

[Table 2]

Sample No. 1 was made of TiO ₂ Is 44 mol%, which is outside the specific range of the present invention, and the other components SrO, BaO, SrO, and CaO are all within the specific range, and the calcination temperature is 1,300 ° C., which is the optimum temperature. However, the porcelain was in a sintered state having water absorption and had low electric properties and low mechanical strength.
[0047]
In Nos. 2 to 4, the component amounts of the basic composition were out of the specified range, and the compounding ratio of SrO and CaO was also out of the range, εr and Qf were low, and the tendency of remarkable deterioration in high-temperature load life characteristics was observed. .
[0048]
Examples of Nos. 5 to 6 and Nos. 8 to 14, in particular, samples of No. 8 were prepared by calcining the blended raw materials to adjust the pulverized particle diameter to 0.5 μm to 0.8 μm, and fired at 1300 ° C. The sintered body had a dense surface and a uniform crystal particle diameter of 3 μm to 4 μm. Further, the mechanical strength was as high as 205 MPa, and the electrical characteristics were very excellent, with εr of 151, Qf of 1750, and τf of 0 ppm / ° C., and no deterioration phenomenon was observed in the high-temperature load life characteristics. No. 12 was fired at 1320 ° C. with the pulverized particle diameter after calcination adjusted to 0.5 μm to 0.8 μm. The sintered state was good, the mechanical strength was as high as 200 MPa, and the electrical characteristics were as high as εr as 163, the Qf was 1800, and the τf was negatively small at −7 ppm / ° C. and could be controlled. In addition, the crystal particle diameter was 3.5 μm to 4.5 μm.
[0049]
Table 3 shows additives and amounts added to the basic composition of the present invention, and Table 4 shows various properties. As in Tables 1 and 2, those with no marks indicate the examples, and those marked with * are examples outside the range.
[0050]
[Table 3]

[Table 4]

Sample No. 8 shows an example of the present invention having a basic composition to which the additives shown in Tables 1 and 2 are not added, and is listed in the same table to show the effect of the additive component blending. Samples Nos. 16 to 22 had additives added within the range specified in the present invention, and were each sintered at 1270 ° C. to 1300 ° C. and had a uniform average crystal grain size of about 0.8 μm to 3.5 μm. Was. The mechanical strength is improved as compared with Sample No. 8 to which no additive is added. Further, εr of the electrical characteristics is stable, and Qf is remarkably improved. Τf can be freely and positively and negatively controlled, and the effect of the additive was recognized.
[0051]
FIG. 2 shows the relationship between Qf and τf with respect to changes in temperature and frequency in Sample No. 22 to which the additive was added and Sample No. 8 in which the additive was not added. As is clear from the figure, the change in the characteristic values of Qf and τf is small and stable even at frequencies of 3 GHz and 7 GHz over the temperature range of −20 ° C. to 80 ° C., as compared to sample No. 8. Is recognized.
[0052]
FIG. 3 shows the relationship between C (capacitance value), Q (no-load loss coefficient), and C-TC (temperature characteristics of capacitance value) with respect to changes in temperature and frequency of a sample manufactured as a capacitor using sample No. 22. Show. As shown in the figure, in Sample No. 22, the change in C, Q, and C-TC was small with respect to a change in frequency from 1 KHz to 0.1 GHz, and was remarkable even with a change in temperature from -20 ° C to 80 ° C. Shows stable characteristics. Sample Nos. 23, 24, and 27 were all inferior in characteristics because the additives were out of the range.
[0053]
Samples Nos. 25 and 26 were prepared by adding MNo. ₂ 0.2, Fe ₂ O ₃ 0.2, Co ₃ O ₄ 0.5, Nb ₂ O ₅ 2.0, Ta ₂ O ₅ And 1.5 parts by weight of MNo. ₂ 0.1, Co ₃ O ₄ To 3.0, Nb ₂ O ₅ Was added and baked at 1320 ° C. The sintered porcelain has a small average crystal grain size of about 1.3 μm to 2.0 μm and is uniform. As shown in Table 4, the mechanical strength and the electrical characteristics εr are high, and the Qf and τf can be controlled to be negatively small and extremely excellent. I have. After the test at a temperature of 80 ° C. and a humidity of 85% for 500 hours, there was almost no change in the life characteristics, and the microwave dielectric porcelain was excellent.
[0054]
Tables 5 and 6 show the relationship between the air-permeable porous sintered body container used for calcination and firing of the porcelain composition of the present invention and the properties of the obtained porcelain composition. In these tables, the cases where the gas-permeable porous sintered body container used for firing satisfies the specific requirements of the present invention are indicated by Nos without * marks on the sample Nos. The example which does not satisfy the specific requirements of the invention is shown. Specifically, the composition of Sample No. 8 was used as a representative example of the basic composition shown in Tables 1 and 2, and the pellets for calcining were determined based on the relationship between the porosity and various characteristics of the gas-permeable porous sintered body container of the present invention. The relationship between the size, the calcining temperature, and the electrical characteristics of the shaped body was examined.
[0055]
[Table 5]

[Table 6]

As is clear from Tables 5 and 6, when the average porosity is out of the specific range, the porcelain obtained has a large variation in the sintered state and is poor in uniformity regardless of other conditions.
[0056]
Sample Nos. 31 to 35 showing the examples of the present invention are examples in which the pellet shape, the calcination temperature, the crushed particle size after calcination, and the calcination temperature were changed within a specific range, and all obtained good porcelain. The mechanical strength was as high as 190 MPa to 205 MPa, and the electrical characteristics were extremely stable and showed good values. Furthermore, Samples Nos. 42 and 43 are examples using the compositions of Sample Nos. 25 shown in Tables 3 and 4, and both show good electrical characteristics.
[0057]
On the other hand, in the sample No. 28 using the air-permeable porous sintered body container having an average porosity of 10% to 23% out of the specified range, the porcelain obtained even if other conditions are satisfied is The variation in the sintering state was large and the uniformity was poor, and was not suitable for mass production.
[0058]
In sample No. 29, the mechanical strength of the porcelain obtained from the container having a large average porosity of 55% to 70% out of the specified range was low, and εr of the electrical characteristics showed a tendency to significantly decrease. In sample No. 30, when the pellet shape for calcining was small, εr tended to decrease. This is considered to be due to the non-uniform evaporation of the Bi and Li components. Also, Nos. 36 to 41 were poor in characteristics because any of the conditions were out of the range as is clear from the table.
[0059]
【The invention's effect】
As described above, the microwave dielectric porcelain composition of the present invention, which contains the Bi and Li components, has a εr of 145 or more in a high-frequency region by controlling each composition component within a specific range. And Qf is as large as 1700 or more, and τf can be freely controlled from zero to positive or negative.
[0060]
Further, by adding a specific additive to the basic composition component, εr and Qf are further increased, and τf can be freely controlled from zero to positive or negative, and can be stabilized.
[0061]
Furthermore, in the calcination and baking in the production process, by using a gas-permeable porous sintered container made of alumina or alumina-zircon, zirconia, or mullite having an average porosity in the range of 25% to 50%. It is possible to minimize evaporation of Bi and Li components and obtain a uniform microwave dielectric porcelain having good electric characteristics.
[0062]
The microwave dielectric porcelain composition of the present invention, which is a basic composition component containing Bi and Li components, has excellent life characteristics, and therefore has a multilayer circuit board, particularly a resonator material and a filter material used in a high frequency region. , And can be used as an isolator component and a capacitor element material.
[0063]
In addition, because of its high mechanical strength, the product shape can be designed to be small as a part, and it is possible to produce a highly reliable part even when used under extremely severe environments while being lighter and thinner. The utility value in industrial fields such as the information and communication field in the future is great.
[Brief description of the drawings]
FIG. 1 shows a gas-permeable porous sintered body container used for calcination and firing of the microwave dielectric porcelain of the present invention.
FIG. 2 shows the relationship between Qf and τf with respect to temperature and frequency changes of the microwave dielectric porcelain of the present invention.
FIG. 3 shows a relationship between C, Q, and C-TC with respect to a change in temperature and frequency.
[Explanation of symbols]
1 Porous porous sintered body container
2 Zirconia component
3 ventilation holes

Claims

Basic composition component, in terms of _oxide, chosen _{aTiO 2 -bSrO-cBaO-dCaO-} eBi 2 O 3 -fLi 2 O-gLn 2 O 3 (Ln is La, Pr, Nd, from lanthanides of Sm One or two or more)
When a + b + c + d + e + f + g = 100 mol%, each of a to g is mol%, and 45 ≦ a ≦ 71, 0.4 ≦ b ≦ 6, 0.2 ≦ c ≦ 18, 0.2 ≦ d ≦ 18. , 0.2 ≦ e ≦ 10, 1 ≦ f ≦ 13, 2 ≦ g ≦ 15,
And,
Each mixing ratio of bSrO and cBaO, bSrO and dCaO is
A microwave dielectric porcelain composition wherein b: c is 1: 0.3 to 1:20 and b: d is 1: 0.3 to 1:20.

One or more of MNo ₂ , Fe ₂ O ₃ , Co ₃ O ₄ , Nb ₂ O ₅ , and Ta ₂ O ₅ as additives are added to 100 parts by weight of the basic composition component as oxides. 2. The microwave dielectric porcelain composition according to claim 1, comprising 0.1 to 10 parts by weight.

Basic composition, in terms of _{oxide, aTiO 2 -bSrO-cBaO-dCaO} -eBi 2 O 3 -fLi 2 O-gLn 2 O 3 (Ln is selected La, Pr, Nd, from lanthanide group elements of Sm 1 Species or two or more)
When a + b + c + d + e + f + g = 100 mol%, each of a to g is mol%, and 45 ≦ a ≦ 71, 0.4 ≦ b ≦ 6, 0.2 ≦ c ≦ 18, 0.2 ≦ d ≦ 18. , 0.2 ≦ e ≦ 10, 1 ≦ f ≦ 13, 2 ≦ g ≦ 15,
And,
Each mixing ratio of bSrO and cBaO, bSrO and dCaO is
a mixture in which b: c is 1: 0.3 to 1:20 and b: d is 1: 0.3 to 1:20,
Molded into granular or massive pellets with a diameter in the range of 1 to 12 mm,
The average porosity of the _Al 2 _{O 3} or _{_{_{_{Al 2 O 3 -ZrSiO 4, ZrO}}}} 2, Al 2 O 3 1 or in -SiO ₂ or more complexes within a range of 25% to 50% Calcined in a temperature range of 900 ° C to 1200 ° C using an air-permeable porous sintered body container,
The obtained calcined product is pulverized and adjusted to an average particle diameter of 0.3 μm to 2.0 μm to prepare a calcined powder,
An organic binder is added to the calcined powder, molded, and fired at a temperature of 1200 ° C. to 1400 ° C. using the air-permeable porous sintered body container.