JP2007197233A - Dielectric ceramic and manufacturing method of dielectric ceramic, as well as laminated ceramic capacitor - Google Patents

Dielectric ceramic and manufacturing method of dielectric ceramic, as well as laminated ceramic capacitor Download PDF

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JP2007197233A
JP2007197233A JP2006015386A JP2006015386A JP2007197233A JP 2007197233 A JP2007197233 A JP 2007197233A JP 2006015386 A JP2006015386 A JP 2006015386A JP 2006015386 A JP2006015386 A JP 2006015386A JP 2007197233 A JP2007197233 A JP 2007197233A
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Takashi Hiramatsu
隆 平松
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Murata Mfg Co Ltd
株式会社村田製作所
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<P>PROBLEM TO BE SOLVED: To realize a dielectric ceramic which has a good dielectric characteristic and can get desired good reliability without deteriorating the temperature characteristic even when the thickness of the dielectric ceramic layer is thinly layered under 1 μm, and to realize a laminated ceramic capacitor using the same. <P>SOLUTION: The dielectric ceramic layers 1a-1g (not shown in the figure) of the laminated ceramic capacitor contain (Ba, Ca)<SB>m</SB>TiO<SB>3</SB>(wherein, m is 0.998-1.020, and the molar quantity of the contained Ca component is 0-15 parts by mol against 100 parts by mol of Ti component) as a main component, and a given molar quantity of SiO<SB>2</SB>, V<SB>2</SB>O<SB>5</SB>, MnO, MgO and specified rare earth oxides as a sub component. In addition, the component V is uniformly dispersed in the grain boundaries and hardly exists in the main component. The dielectric ceramic can be manufactured by adding SiO<SB>2</SB>-V<SB>2</SB>O<SB>5</SB>in a form of mixed crystals to the main component that is highly crystallized. <P>COPYRIGHT: (C)2007,JPO&INPIT

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本発明は誘電体セラミック及び該誘電体セラミックの製造方法、並びに積層セラミックコンデンサに関し、より詳しくは小型・大容量の積層セラミックコンデンサ用誘電体材料に適した誘電体セラミック、及びその製造方法、並びに該誘電体セラミックを使用して製造された積層セラミックコンデンサに関する。   The present invention relates to a dielectric ceramic, a method for manufacturing the dielectric ceramic, and a multilayer ceramic capacitor, and more particularly, a dielectric ceramic suitable for a dielectric material for a small and large capacity multilayer ceramic capacitor, a method for manufacturing the dielectric ceramic, and the method The present invention relates to a multilayer ceramic capacitor manufactured using a dielectric ceramic.
近年におけるエレクトロニクス技術の発展に伴い、積層セラミックコンデンサの小型化、大容量化の進展が顕著であるが、この種の積層セラミックコンデンサは、誘電体セラミック層の積層焼結体であるセラミック焼結体の内部に内部電極が並列状に埋設されており、前記誘電体セラミック層を薄層化・多層化することにより、小型化、大容量化が図られている。   With the recent development of electronics technology, the progress of downsizing and increasing the capacity of multilayer ceramic capacitors is remarkable. This type of multilayer ceramic capacitor is a ceramic sintered body that is a multilayer sintered body of dielectric ceramic layers. The internal electrodes are embedded in parallel, and the dielectric ceramic layer is made thin and multi-layered to reduce the size and increase the capacity.
また、この種の積層セラミックコンデンサでは、静電容量の温度特性が良好であることも求められており、したがって薄層化しても比誘電率が高く、静電容量の温度変化率も小さく、しかも絶縁性が高く、高温負荷時の故障寿命が長い信頼性に優れた誘電体セラミックの研究・開発が盛んに行われている。   In addition, this type of multilayer ceramic capacitor is also required to have good capacitance temperature characteristics. Therefore, even if it is thinned, the relative dielectric constant is high, the capacitance temperature change rate is small, and Research and development of highly reliable dielectric ceramics with high insulation properties and long failure life under high temperature load are being actively conducted.
ところで、従来の誘電体セラミックは、比較的低い電界強度での使用を前提としており、このため高い電界強度で使用すると絶縁性が低下したり高温負荷時の故障寿命が低下し、信頼性の低下を招くという欠点があった。   By the way, the conventional dielectric ceramics are premised on the use with a relatively low electric field strength. For this reason, when used at a high electric field strength, the insulation performance is lowered, the failure life at high temperature load is lowered, and the reliability is lowered. There was a drawback that invited.
そこで、従来より、一般式:(Ba1-x CaTiO+α1 BaO+αCaO+βVで表わされ(α1 及びαは、それぞれα1 =0及びα2 =0の場合を含み、mは、m≧0.990であり、βは、0.0001≦β≦0.025であり、xは、0.02≦x≦0.15であり、α1 、α2 およびmは、1.005<m+α1 +α2 ≦1.035である。)、かつ前記(Ba1-x CaTiOで表わされる化合物100重量部に対して、焼結助剤が0.2〜5.0重量部含有された誘電体セラミック組成物が提案されている。 Therefore, conventionally, it is represented by the general formula: (Ba 1−x Ca x ) m TiO 3 + α 1 BaO + α 2 CaO + βV 2 O 51 and α 2 are α 1 = 0 and α 2 = 0, respectively. In some cases, m is m ≧ 0.990, β is 0.0001 ≦ β ≦ 0.025, x is 0.02 ≦ x ≦ 0.15, and α 1 , α 2 And m is 1.005 <m + α 1 + α 2 ≦ 1.035), and 100 parts by weight of the compound represented by (Ba 1-x Ca x ) m TiO 3 is a sintering aid. Dielectric ceramic compositions containing 0.2 to 5.0 parts by weight have been proposed.
特許文献1では、上記組成を有する誘電体セラミック組成物を使用することにより、誘電体セラミック層の厚みが2μm程度になっても、静電容量の温度特性を損なうこともなく、比誘電率εrが2000以上、比抵抗ρが1013Ω・cm以上、高温負荷時の平均故障寿命が50時間以上の積層セラミックコンデンサを得ることができる。 In Patent Document 1, by using the dielectric ceramic composition having the above composition, even if the thickness of the dielectric ceramic layer becomes about 2 μm, the temperature characteristics of the capacitance are not impaired, and the relative dielectric constant εr Can be obtained, a multilayer ceramic capacitor having a specific resistance ρ of 10 13 Ω · cm or more and an average failure life under a high temperature load of 50 hours or more.
特開2003−165768号公報JP 2003-165768 A
しかしながら、特許文献1のような従来の誘電体セラミックでは、誘電体セラミック層を1μm以下に薄層化すると、絶縁性や高温負荷時の故障寿命が低下し、このため所望の信頼性を確保することができなくなるという問題点があった。   However, in the conventional dielectric ceramic as disclosed in Patent Document 1, when the dielectric ceramic layer is thinned to 1 μm or less, the insulation and the failure life at high temperature load are lowered, and thus the desired reliability is ensured. There was a problem that it was impossible.
すなわち、積層セラミックコンデンサでは、一般に、内部電極間に存在する結晶粒子の個数が多くなるほど絶縁性が向上し、故障寿命も長くなる。この現象は、内部電極間に存在する結晶粒子の個数が多くなると結晶粒界の割合も増加することから、結晶粒界の方が結晶粒子よりも比抵抗が高いことを示している。したがって、従来のこの種の誘電体セラミックでは、結晶粒界の方が結晶粒子よりも比抵抗が高く、絶縁性が高いため、結晶粒界に印加される電界は、結晶粒子に印加される電界よりも高い。   That is, in a multilayer ceramic capacitor, generally, the greater the number of crystal grains present between the internal electrodes, the better the insulation and the longer the failure life. This phenomenon indicates that the crystal grain boundary has a higher specific resistance than the crystal grain because the ratio of the crystal grain boundary increases as the number of crystal grains present between the internal electrodes increases. Therefore, in this type of conventional dielectric ceramic, since the grain boundary has higher specific resistance and higher insulation than the crystal grain, the electric field applied to the crystal grain boundary is the electric field applied to the crystal grain. Higher than.
しかしながら、上記従来の誘電体セラミックでは、誘電体セラミック層の厚みを1μm以下に薄層化すると、内部電極間に存在する結晶粒子の個数が減少してくるため、結晶粒界に高電界が印加されることとなり、その結果故障寿命が低下し、所望の信頼性を確保することができないという問題点があった。   However, in the above conventional dielectric ceramic, when the thickness of the dielectric ceramic layer is reduced to 1 μm or less, the number of crystal grains existing between the internal electrodes decreases, so that a high electric field is applied to the crystal grain boundary. As a result, the failure life is reduced, and there is a problem that desired reliability cannot be ensured.
本発明はこのような事情に鑑みなされたものであって、誘電体セラミック層の厚みを1μm以下に薄層化しても温度特性を損なうことなく、良好な誘電特性を有し、かつ所望の良好な信頼性を得ることができる誘電体セラミック、及びその製造方法、並びに該誘電体セラミックを使用した小型・大容量の積層セラミックコンデンサを提供することを目的とする。   The present invention has been made in view of such circumstances, and even if the thickness of the dielectric ceramic layer is reduced to 1 μm or less, it has good dielectric properties without deteriorating temperature characteristics, and desired good It is an object of the present invention to provide a dielectric ceramic capable of obtaining high reliability, a manufacturing method thereof, and a small-sized and large-capacity multilayer ceramic capacitor using the dielectric ceramic.
本発明者は上記目的を達成するために鋭意研究したところ、(Ba,Ca)TiOを主成分とし、SiO、V、MnO、MgO、及びR(希土類酸化物)を含む誘電体セラミックにおいて、V成分を結晶粒界に均一に分散させ、かつ結晶粒子にはV成分が殆ど存在しないようにすることにより、誘電体セラミック層の厚みを1μm以下に薄層化しても、静電容量の温度特性を損なうことなく、高比誘電率を有し、誘電損失も低く、静電容量のDCバイアス特性も良好であり、かつ所望の良好な信頼性を確保できる誘電体セラミックを得ることができるという知見を得た。 The present inventor has intensively studied to achieve the above object, and has (Ba, Ca) m TiO 3 as a main component, SiO 2 , V 2 O 5 , MnO, MgO, and R x O y (rare earth oxide). ), The thickness of the dielectric ceramic layer is reduced to 1 μm or less by uniformly dispersing the V component at the crystal grain boundaries and making the crystal particles have almost no V component. However, it does not impair the temperature characteristics of the capacitance, has a high relative dielectric constant, low dielectric loss, good capacitance DC bias characteristics, and can ensure the desired good reliability. The knowledge that a body ceramic can be obtained was acquired.
具体的には、結晶粒界の成分分析を行った場合、V成分の含有モル量を副成分として添加された前記V成分の総含有モル量の2倍以上とする分析点が、結晶粒界中、全分析点の80%以上であったことから、V成分は結晶粒界中に均一に分散していると判断することができる。   Specifically, when the component analysis of the crystal grain boundary is performed, the analysis point where the molar content of the V component is at least twice the total molar content of the V component added as a subcomponent is the grain boundary. Among these, since it was 80% or more of the total analysis points, it can be determined that the V component is uniformly dispersed in the crystal grain boundaries.
一方、結晶粒子については、V成分の含有モル量がTi成分100モル部に対し0.04モル部以上の結晶粒子の占める比率が、全結晶粒子中の5%以下であれば、前記主成分中のV成分量は所定微少量以下であってV成分は主成分に殆ど固溶していないと考えられ、したがって結晶粒子内にはV成分が殆ど存在しないと判断することができる。   On the other hand, for the crystal particles, if the proportion of the crystal component having a V component content of 0.04 mol part or more with respect to 100 mol parts of the Ti component is 5% or less in the total crystal particles, the main component The amount of the V component is less than a predetermined minute amount, and it is considered that the V component is hardly dissolved in the main component. Therefore, it can be determined that the V component is hardly present in the crystal grains.
本発明はこのような知見に基づきなされたものであって、本発明に係る誘電体セラミックは、(Ba,Ca)TiO(ただし、mは0.998〜1.020であり、Ca成分の含有モル量はTi成分100モル部に対し0〜15モル部である。)を主成分とし、副成分としてSiO、V、MnO、MgO、及びR(ただし、Rは、Y、La、CeO、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、及びLuの中から選択された少なくとも1種以上を示す。)を含有し、前記各副成分の含有モル量は、Ti成分100モル部に対し、SiOが0.5〜8.0モル部、Vが0.02〜1.0モル部、MnOが0.01〜5.0モル部、MgOが0.05〜3.0モル部、及びRが0.05〜2.5モル部であり、かつ、前記結晶粒界の成分分析を行った場合に、V成分の含有モル量を前記V成分の総含有モル量の2倍以上とする分析点が、結晶粒界中、全分析点の80%以上であり、前記V成分の含有モル量がTi成分100モル部に対し0.04モル部以上の結晶粒子の占める比率が、全結晶粒子中の5%以下(0%を含む。)であることを特徴としている。 The present invention has been made based on such knowledge, and the dielectric ceramic according to the present invention has (Ba, Ca) m TiO 3 (where m is 0.998 to 1.020, and the Ca component). The main component is SiO 2 , V 2 O 5 , MnO, MgO, and R x O y (provided that R x O y ). x O y is, Y 2 O 3, La 2 O 3, CeO 2, Nd 2 O 3, Sm 2 O 3, Eu 2 O 3, Gd 2 O 3, Tb 2 O 3, Dy 2 O 3, Ho 2 At least one selected from O 3 , Er 2 O 3 , Tm 2 O 3 , Yb 2 O 3 , and Lu 2 O 3 ). , to Ti component 100 molar parts, SiO 2 is 0.5 to 8 0 molar parts, V 2 O 5 is from 0.02 to 1.0 molar parts, MnO is 0.01 to 5.0 molar parts, MgO is 0.05 to 3.0 molar parts, and R x O y is 0 0.05 to 2.5 mole parts, and when the component analysis of the crystal grain boundary is performed, the analysis point that makes the content mole amount of the V component more than twice the total mole content of the V component is In the crystal grain boundary, the proportion of the crystal grains which are 80% or more of the total analysis points and the content of the V component is 0.04 mole part or more with respect to 100 mole parts of the Ti component is It is characterized by being 5% or less (including 0%).
さらに、本発明者が鋭意研究を重ねたところ、Ca成分の含有モル量をTi成分100モル部に対し2モル部未満とすることにより、静電容量のDCバイアス特性をより一層向上させることができ、またCa成分の含有モル量をTi成分100モル部に対し2〜15モル部とすることにより、故障寿命をより一層向上させることができることが分かった。   Furthermore, when this inventor repeated earnest research, the DC bias characteristic of an electrostatic capacitance can be improved further by making the content molar amount of Ca component into less than 2 mol parts with respect to 100 mol parts of Ti components. It was also found that the failure life can be further improved by setting the molar content of the Ca component to 2 to 15 mol parts relative to 100 mol parts of the Ti component.
すなわち、本発明の誘電体セラミックは、Ca成分の含有モル量が、Ti成分100モル部に対し2モル部未満であることを特徴とし、又は、Ca成分の含有モル量が、Ti成分100モル部に対し2〜15モル部であることを特徴としている。   That is, the dielectric ceramic of the present invention is characterized in that the molar content of the Ca component is less than 2 molar parts relative to 100 molar parts of the Ti component, or the molar content of Ca component is 100 molar of the Ti component. It is characterized by being 2 to 15 mol parts per part.
また、上記誘電体セラミックは、高結晶化度を有する主成分にSiO−V混晶物、及びMnO、MgO、及び上述した特定の希土類酸化物を配合することにより製造することができる。 The dielectric ceramic can be manufactured by blending a main component having high crystallinity with a SiO 2 —V 2 O 5 mixed crystal, MnO, MgO, and the specific rare earth oxide described above. it can.
すなわち、本発明に係る誘電体セラミックの製造方法は、(Ba,Ca)TiO(ただし、mは0.998〜1.020であり、Ca成分の含有モル量はTi成分100モル部に対し0〜15モル部である。)で表される主成分を作製する主成分作製工程と、SiOとVとを配合して得た配合物に熱処理を施して溶融させた後、急冷してSiO−V混晶物を得る混晶物作製工程と、前記主成分、前記SiO−V混晶物、MnO、MgO、及びR(Rは、Y、La、CeO、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、及びLuの中から選択された少なくとも1種以上を示す。)を配合して配合物を作製する配合物作製工程と、前記配合物に焼成処理を施してセラミック焼結体を作製する焼結体作製工程とを含むことを特徴としている。 That is, the method for producing a dielectric ceramic according to the present invention provides (Ba, Ca) m TiO 3 (where m is 0.998 to 1.020, and the molar content of the Ca component is 100 mol parts of the Ti component). After the main component production step for producing the main component represented by 0) to 15 mol parts) and the composition obtained by blending SiO 2 and V 2 O 5 are heat-treated and melted. , Rapid cooling to obtain a SiO 2 —V 2 O 5 mixed crystal, and the main component, the SiO 2 —V 2 O 5 mixed crystal, MnO, MgO, and R x O y (R x O y is, Y 2 O 3, La 2 O 3, CeO 2, Nd 2 O 3, Sm 2 O 3, Eu 2 O 3, Gd 2 O 3, Tb 2 O 3, Dy 2 O 3, Ho 2 O 3, Er 2 O 3, Tm 2 O 3, Yb 2 O 3, and Lu 2 O 3 At least one selected from the above.) And a sintered body preparation step of preparing a ceramic sintered body by subjecting the mixture to a firing treatment. It is characterized by including.
また、本発明に係る積層セラミックコンデンサは、複数の誘電体層を積層したセラミック積層体が焼結されてなるセラミック焼結体と、該セラミック焼結体の内部に並列状に埋設された複数の内部電極と、前記セラミック焼結体の外表面に形成された外部電極とを備えた積層セラミックコンデンサにおいて、前記セラミック焼結体が、上記誘電体セラミックで形成されていることを特徴としている。   The multilayer ceramic capacitor according to the present invention includes a ceramic sintered body obtained by sintering a ceramic multilayer body in which a plurality of dielectric layers are laminated, and a plurality of ceramic ceramics embedded in parallel in the ceramic sintered body. In a multilayer ceramic capacitor including an internal electrode and an external electrode formed on an outer surface of the ceramic sintered body, the ceramic sintered body is formed of the dielectric ceramic.
本発明の誘電体セラミックによれば、(Ba,Ca)TiOを主成分とし、SiO、V、MnO、MgO、及びRを含む誘電体セラミックにおいて、V成分が結晶粒界に均一に分散し、かつ結晶粒子には殆ど存在しないように形成されているので、結晶粒界の比抵抗が低くなって該結晶粒界に印加される電界強度を低下させることが可能となる。したがって、誘電体セラミック層の厚みを1μm以下に薄層化しても、誘電体セラミックとしての諸特性(比誘電率、誘電損失、温度特性、DCバイアス特性)が良好で、しかも信頼性の優れた誘電体セラミックを得ることができる。 According to the dielectric ceramic of the present invention, in the dielectric ceramic containing (Ba, Ca) m TiO 3 as a main component and containing SiO 2 , V 2 O 5 , MnO, MgO, and R x O y , the V component is Since it is formed so that it is uniformly dispersed in the crystal grain boundary and hardly exists in the crystal grain, the specific resistance of the crystal grain boundary is lowered and the electric field strength applied to the crystal grain boundary can be reduced. It becomes possible. Therefore, even if the thickness of the dielectric ceramic layer is reduced to 1 μm or less, various characteristics (dielectric constant, dielectric loss, temperature characteristics, DC bias characteristics) as a dielectric ceramic are good and excellent in reliability. A dielectric ceramic can be obtained.
具体的には、比誘電率εrが2500以上、誘電損失tanδが10%以内であり、静電容量の温度特性はJISに規定するB特性(+20℃を基準とした静電容量の容量変化率が−25℃〜+85℃の温度範囲で±10%以内)を満足し、DCバイアスを印加したときの静電容量の変化率(DC変化率)を25%以下に抑制することができ、しかも比抵抗ρが1010.5Ω・m以上、高温負荷時の故障寿命が100時間以上の信頼性に優れた誘電体セラミックを得ることができる。 Specifically, the relative dielectric constant εr is 2500 or more, the dielectric loss tanδ is within 10%, and the temperature characteristic of the capacitance is the B characteristic defined in JIS (capacitance change rate of the capacitance based on + 20 ° C.). Is within ± 10% in the temperature range of -25 ° C to + 85 ° C), and the rate of change in capacitance (DC rate of change) when a DC bias is applied can be suppressed to 25% or less. A dielectric ceramic excellent in reliability with a specific resistance ρ of 10 10.5 Ω · m or more and a failure life at a high temperature load of 100 hours or more can be obtained.
また、Ca成分の含有モル量が、Ti成分100モル部に対し2モル部未満とすることにより、静電容量のDCバイアス特性をより一層向上させることができ、また、Ca成分の含有モル量が、Ti成分100モル部に対し2〜15モル部とすることにより、故障寿命をより一層向上させることができる。したがって、DCバイアス特性又は故障寿命の優先度に応じてCa成分の含有モル量を選択して使い分けることにより、用途に応じた誘電体セラミックを得ることができる。   Moreover, when the content of the Ca component is less than 2 parts by mole with respect to 100 parts by mole of the Ti component, the DC bias characteristics of the electrostatic capacity can be further improved. However, a failure life can be further improved by setting it as 2-15 mol part with respect to 100 mol part of Ti components. Therefore, the dielectric ceramic according to a use can be obtained by selecting and using properly the content amount of Ca component according to the DC bias characteristic or the priority of the failure life.
また、本発明の誘電体セラミックの製造方法によれば、主成分作製工程で作製された所定の高結晶化度を有する主成分と、混晶物作製工程で得られたSiO−V混晶物と、MnO、MgO、及び特定の希土類酸化物とを配合して配合物を作製し、その後焼成処理を行ってセラミック焼結体を得るようにしているので、V成分が結晶粒界に均一に分散し、かつ結晶粒子にはV成分が殆ど存在しない誘電体セラミックを製造することができる。 Moreover, according to the dielectric ceramic manufacturing method of the present invention, the main component having a predetermined high crystallinity produced in the main component production step and the SiO 2 —V 2 O obtained in the mixed crystal production step. 5 A mixed crystal, MnO, MgO, and a specific rare earth oxide are blended to prepare a blend, and then a firing treatment is performed to obtain a ceramic sintered body. It is possible to produce a dielectric ceramic that is uniformly dispersed in the boundary and has almost no V component in the crystal grains.
本発明の積層セラミックコンデンサによれば、複数の誘電体層を積層したセラミック積層体が焼結されてなるセラミック焼結体と、該セラミック焼結体の内部に並列状に埋設された複数の内部電極と、前記セラミック焼結体の外表面に形成された外部電極とを備えた積層セラミックコンデンサにおいて、前記セラミック焼結体が、上記誘電体セラミックで形成されているので、誘電体セラミック層1層当たりの厚みが1μm以下でありながら、比誘電率等の諸特性が良好であり、かつ、信頼性の優れた小型・大容量の積層セラミックコンデンサを得ることができる。   According to the multilayer ceramic capacitor of the present invention, a ceramic sintered body obtained by sintering a ceramic multilayer body in which a plurality of dielectric layers are laminated, and a plurality of internal parts embedded in parallel in the ceramic sintered body. In a multilayer ceramic capacitor comprising an electrode and an external electrode formed on the outer surface of the ceramic sintered body, the ceramic sintered body is formed of the dielectric ceramic, so that one dielectric ceramic layer While the per-thickness is 1 μm or less, it is possible to obtain a small-sized and large-capacity monolithic ceramic capacitor having excellent characteristics such as relative dielectric constant and excellent reliability.
次に、本発明の実施の形態を詳説する。   Next, an embodiment of the present invention will be described in detail.
本発明に係る誘電体セラミックは、所定比率に配合されたペロブスカイト型結晶構造(一般式ABO)を有する(Ba,Ca)TiOを主成分とし、副成分としてSiO、V、MnO、MgO、及びR(特定の希土類酸化物)を所定範囲で含有し、V成分が結晶粒界中に均一に分散されると共に、前記主成分中にV成分が殆ど固溶しないように形成されている。 The dielectric ceramic according to the present invention is mainly composed of (Ba, Ca) m TiO 3 having a perovskite crystal structure (general formula ABO 3 ) blended at a predetermined ratio, and SiO 2 and V 2 O 5 as subcomponents. , MnO, MgO, and R x O y (specific rare earth oxide) in a predetermined range, the V component is uniformly dispersed in the crystal grain boundary, and the V component is almost dissolved in the main component. It is formed so as not to.
このように本発明の誘電体セラミックは、上記主成分及び副成分を含有すると共に、V成分が結晶粒界中に均一に分散し、かつ、主成分に対しては難固溶となるように形成されているので、静電容量の温度特性を損なうことなく、低誘電損失で高比誘電率を有し、静電容量のDCバイアス特性も良好で、かつ絶縁性が高く、高温負荷時の故障寿命の長い信頼性の優れた誘電体セラミックを得ることができる。   As described above, the dielectric ceramic of the present invention contains the above-mentioned main component and subcomponent, the V component is uniformly dispersed in the crystal grain boundary, and is hardly soluble in the main component. Since it is formed, it does not impair the temperature characteristics of the capacitance, has a low dielectric loss, a high relative dielectric constant, good capacitance DC bias characteristics, high insulation, and high temperature load A dielectric ceramic with a long failure life and excellent reliability can be obtained.
すなわち、〔発明が解決しようとする課題〕の項でも述べたように、特許文献1のような従来の誘電体セラミックでは、誘電体セラミック層の厚みが1μm以下に薄層化してくると、厚み方向に存在する結晶粒子の個数が少なくなるため、結晶粒界の割合も減少する。それにも拘らず、絶縁性の高い結晶粒界に高い電界強度が印加されるため、故障寿命が短くなり、所望の信頼性を確保できなくなる。   That is, as described in the section of [Problems to be Solved by the Invention], in the conventional dielectric ceramic as in Patent Document 1, when the thickness of the dielectric ceramic layer is reduced to 1 μm or less, the thickness is reduced. Since the number of crystal grains present in the direction decreases, the ratio of crystal grain boundaries also decreases. Nevertheless, since a high electric field strength is applied to the highly insulating crystal grain boundary, the failure life is shortened and desired reliability cannot be ensured.
そこで、本実施の形態では、V成分が比抵抗を低下させる作用を有する点に着目し、V成分を結晶粒界に均一に分散させ、かつ、主成分中にV成分を殆ど固溶させないようにし、これにより結晶粒界の比抵抗を低下させて該結晶粒界に印加される電界強度を弱めている。そして、このようにすることにより誘電体セラミックの厚みが1μm以下、例えば0.7μm程度になっても、常温使用時の絶縁性が良好で、高温負荷時の故障寿命の長い信頼性の優れた誘電体セラミックを得ることができる。   Therefore, in the present embodiment, attention is paid to the fact that the V component has an effect of reducing the specific resistance, so that the V component is uniformly dispersed in the crystal grain boundary and the V component is hardly dissolved in the main component. Thus, the specific resistance of the crystal grain boundary is reduced, and the electric field strength applied to the crystal grain boundary is weakened. By doing so, even when the thickness of the dielectric ceramic is 1 μm or less, for example, about 0.7 μm, the insulation at normal temperature is good and the reliability is long and the life at failure is high at high temperature load. A dielectric ceramic can be obtained.
しかも、主成分及び副成分が所定比率で配合されているので、静電容量の温度特性を損なうことなく、静電容量のDCバイアス特性も良好な低誘電損失で高比誘電率を有する誘電体セラミックを得ることができる。   In addition, since the main component and the subcomponent are blended at a predetermined ratio, the dielectric having a high dielectric constant with a low dielectric loss and an excellent DC bias characteristic of the capacitance without impairing the temperature characteristics of the capacitance. Ceramic can be obtained.
ここで、V成分の結晶粒界中への均一分散性の尺度としては、種々考えられるが、本実施の形態では、結晶粒界の成分分析を行った場合に、V成分の含有モル量を前記V成分の総含有モル量の2倍以上とする分析点が、結晶粒界中、全分析点の80%以上であれば、均一分散性を有すると判断している。   Here, various measures of uniform dispersion of the V component in the crystal grain boundary are conceivable. In the present embodiment, when component analysis of the crystal grain boundary is performed, the content molar amount of the V component is determined. If the analysis point to be at least twice the total molar content of the V component is 80% or more of the total analysis point in the crystal grain boundary, it is determined that it has uniform dispersibility.
また、V成分の主成分中への難固溶性の尺度についても、種々考えられるが、本実施の形態では、V成分の含有モル量がTi成分100モル部に対し0.04モル部以上の結晶粒子の占める比率が、全結晶粒子中の5%以下(0%を含む。)であれば、難固溶性を有すると判断している。   In addition, various measures of poor solubility in the main component of the V component are conceivable. In the present embodiment, the molar content of the V component is 0.04 mol part or more with respect to 100 mol parts of the Ti component. If the proportion of crystal grains is 5% or less (including 0%) in all crystal grains, it is determined that the crystal grains have poor solid solubility.
また、本実施の形態では、主成分中のAサイト(Ba,Ca)とBサイト(Ti)との配合モル比mは、0.998〜1.020、Ca成分の含有量がTi成分100モル部に対し、0〜15となるように配合されており、また、前記各副成分の含有モル量は、Ti成分100モル部に対し、SiOが0.5〜8.0モル部、Vが0.02〜1.0モル部、MnOが0.01〜5.0モル部、MgOが0.05〜3.0モル部、及びRが0.05〜2.5モル部となるように配合されているが、これらの限定理由は以下の通りである。 Moreover, in this Embodiment, the compounding molar ratio m of A site (Ba, Ca) and B site (Ti) in a main component is 0.998 to 1.020, and content of Ca component is Ti component 100. relative molar parts are formulated to be 0-15, also, the molar content of each subcomponent, with respect to Ti component 100 molar parts, SiO 2 is 0.5 to 8.0 molar parts, V 2 O 5 is from 0.02 to 1.0 molar parts, MnO is 0.01 to 5.0 molar parts, MgO is 0.05 to 3.0 molar parts, and R x O y is 0.05 to 2 Although it mix | blends so that it may become 5 mol part, the reasons for these limitation are as follows.
(1)配合モル比m
配合モル比mは誘電体セラミックの諸特性に影響を及ぼすが、配合モル比mが0.998未満になると、比抵抗が小さくなり、また故障寿命も短くなって所望の信頼性を得ることができなくなる。一方、配合モル比mが1.020を超えると、比誘電率や誘電損失等の誘電特性が劣化し、また、比抵抗も低く、故障寿命も短くなって所望の信頼性を確保できなくなる。
(1) Mixing molar ratio m
The compounding molar ratio m affects various characteristics of the dielectric ceramic. However, when the compounding molar ratio m is less than 0.998, the specific resistance is reduced and the failure life is shortened, and the desired reliability can be obtained. become unable. On the other hand, when the blending molar ratio m exceeds 1.020, dielectric properties such as relative permittivity and dielectric loss are deteriorated, the specific resistance is low, the failure life is shortened, and desired reliability cannot be ensured.
そこで、本実施の形態では、配合モル比mを0.998〜1.020としている。 Therefore, in the present embodiment, the blending molar ratio m is set to 0.998 to 1.020.
(2)Ca成分の含有モル量
Ba成分の一部を必要に応じてCa成分と置換することにより、用途に応じた所望の諸特性を有する誘電体セラミックを得ることができる。
(2) Content molar amount of Ca component A dielectric ceramic having desired characteristics according to the application can be obtained by substituting a part of the Ba component with a Ca component as necessary.
しかしながら、Ca成分の含有モル量がTi成分100モル部に対し15モル部を超えると、比誘電率の低下を招き、所望の高比誘電率を有する誘電体セラミックを得ることができなくなる。   However, when the molar content of the Ca component exceeds 15 parts by mole with respect to 100 parts by mole of the Ti component, the dielectric constant is lowered, and a dielectric ceramic having a desired high relative dielectric constant cannot be obtained.
そこで、本実施の形態では、Ca成分の含有モル量をTi成分100モル部に対し0〜15モル部としている。   Therefore, in the present embodiment, the molar content of the Ca component is set to 0 to 15 mol parts with respect to 100 mol parts of the Ti component.
ところで、静電容量のDCバイアス特性は、静電容量のDC変化率で評価することができるが、このDC変化率は、絶対値で25%以下であるのが望ましい。一方、誘電体セラミックに対し、所望の信頼性を得るためには、故障寿命は100時間以上であるのが望ましい。そして、Ca成分の含有モル量をTi成分100モル部に対し、上述した0〜15モル部とすることにより、DC変化率を絶対値で25%以下、故障寿命を100時間以上とすることが可能となる。   By the way, although the DC bias characteristic of the electrostatic capacity can be evaluated by the DC change rate of the electrostatic capacity, the DC change rate is preferably 25% or less in absolute value. On the other hand, in order to obtain a desired reliability for the dielectric ceramic, the failure life is preferably 100 hours or more. Then, by setting the content of the Ca component to 0 to 15 parts by mole with respect to 100 parts by mole of the Ti component, the DC change rate can be 25% or less in absolute value and the failure life can be 100 hours or more. It becomes possible.
しかるに、Ca成分の含有モル量をTi成分100モル部に対し2モル部未満とすると、DC変化率を絶対値で20%以下に抑制することができ、DCバイアス特性のより一層の向上を図ることができる。一方、Ca成分の含有モル量をTi成分100モル部に対し2〜15モル部とすることにより、故障寿命を150時間以上とすることができ、より一層の信頼性向上を図ることができる。   However, when the molar content of the Ca component is less than 2 mol parts with respect to 100 mol parts of the Ti component, the DC change rate can be suppressed to 20% or less in absolute value, and the DC bias characteristics can be further improved. be able to. On the other hand, by setting the molar content of the Ca component to 2 to 15 mol parts with respect to 100 mol parts of the Ti component, the failure life can be increased to 150 hours or more, and the reliability can be further improved.
したがって、Ca成分の含有モル量については、DCバイアス特性又は故障寿命のいずれを優先するかで用途に応じて使い分けることができる。   Therefore, the molar content of the Ca component can be properly used depending on the application depending on which of the DC bias characteristics or the failure life is prioritized.
(3)SiOの含有モル量
SiOはVとの混晶物形態で主成分に添加されるが、SiOの含有モル量がTi成分100モル部に対し0.5モル部未満になると、比誘電率や誘電損失等の誘電特性が悪化し、しかも比抵抗が低下し、故障寿命も短くなって所望の信頼性を確保できなくなる。一方、SiOの含有モル量がTi成分100モル部に対し8.0モル部を超えた場合も、比誘電率が低下し、また静電容量の温度特性が悪化し、さらには故障寿命も低下して所望の信頼性を確保できなくなる。
(3) the molar content of SiO 2 SiO 2 is added to the main component in the mixed crystal product form of V 2 O 5, 0.5 molar parts molar content of SiO 2 is relative to 100 parts by mol Ti component If it is less than 1, the dielectric properties such as the dielectric constant and dielectric loss are deteriorated, the specific resistance is lowered, the failure life is shortened, and the desired reliability cannot be ensured. On the other hand, when the content of SiO 2 exceeds 8.0 parts by mole with respect to 100 parts by mole of the Ti component, the relative dielectric constant decreases, the temperature characteristics of the capacitance deteriorates, and the failure life also increases. The desired reliability cannot be ensured due to the decrease.
そこで、本実施の形態では、SiOの含有モル量をTi成分100モル部に対し0.5〜8.0モル部となるように調製している。 Therefore, in this embodiment, the content molar amount of SiO 2 is adjusted to 0.5 to 8.0 mol parts with respect to 100 mol parts of the Ti component.
(4)Vの含有モル量
VはSiOとの混晶物形態で主成分に添加することにより、V成分は結晶粒界に均一に分散され、かつ結晶粒界には殆ど固溶しない状態で誘電体セラミック中に存在する。しかしながら、Vの含有モル量がTi成分100モル部に対し0.02モル部未満の場合は、V成分の所期の作用効果、すなわち結晶粒界に印加される電界強度を弱めるという作用効果を発揮することができず、故障寿命が短くなって所望の信頼性を得ることができない。一方、Vの含有モル量がTi成分100モル部に対し1.0モル部を超えると、比誘電率が低下して所望の高比誘電率を有する誘電体セラミックを得ることができなくなる。
(4) Content molar amount of V 2 O 5
V 2 O 5 is added to the main component in the form of a mixed crystal with SiO 2 , so that the V component is uniformly dispersed in the crystal grain boundary and is hardly dissolved in the crystal grain boundary. Exists. However, when the molar amount of V 2 O 5 is less than 0.02 mol part with respect to 100 mol parts of the Ti component, the intended effect of the V component, ie, the electric field strength applied to the crystal grain boundary is weakened. The effect cannot be exhibited, the failure life is shortened, and the desired reliability cannot be obtained. On the other hand, when the content molar amount of V 2 O 5 exceeds 1.0 mol part with respect to 100 mol parts of the Ti component, the dielectric constant decreases and a dielectric ceramic having a desired high relative dielectric constant can be obtained. Disappear.
そこで、本実施の形態では、Vの含有モル量をTi成分100モル部に対し0.02〜1.0モル部としている。 Therefore, in the present embodiment, the content molar amount of V 2 O 5 is 0.02 to 1.0 mol part with respect to 100 mol parts of the Ti component.
(5)MnOの含有モル量
MnOは誘電体セラミックの特性向上や信頼性向上に寄与することができるが、MnOの含有モル量がTi成分100モル部に対し0.01モル部未満の場合は、比抵抗が低く、故障寿命も短く、信頼性向上を図ることができない。一方、MnOの含有モル量がTi成分100モル部に対し5.0モル部を超えた場合は比誘電率の低下を招き、また静電容量の温度特性が悪化する。
(5) MnO content molar amount MnO can contribute to improvement of characteristics and reliability of the dielectric ceramic, but when the content molar amount of MnO is less than 0.01 mol parts with respect to 100 mol parts of the Ti component. The specific resistance is low, the failure life is short, and the reliability cannot be improved. On the other hand, when the molar amount of MnO exceeds 5.0 parts by mole with respect to 100 parts by mole of the Ti component, the relative permittivity is lowered and the temperature characteristics of the capacitance are deteriorated.
そこで、本実施の形態では、MnOの含有モル量をTi成分100モル部に対し0.01〜5.0モル部としている。   Therefore, in the present embodiment, the molar amount of MnO is set to 0.01 to 5.0 mole parts with respect to 100 mole parts of the Ti component.
(6)MgOの含有モル量
MgOも誘電体セラミックの特性向上や信頼性向上に寄与することができるが、MgOの含有モル量がTi成分100モル部に対し0.05モル部未満の場合は、比抵抗が低く、故障寿命も短く、所望の信頼性向上を図ることができない。一方、MgOの含有モル量がTi成分100モル部に対し3.0モル部を超えると、静電容量の温度特性が悪化し、また比抵抗の低下を招き、故障寿命も短くなって所望の信頼性を確保できなくなる。
(6) MgO content molar amount MgO can also contribute to improving the characteristics and reliability of the dielectric ceramic, but when the MgO content molar amount is less than 0.05 mol parts with respect to 100 mol parts of the Ti component. The specific resistance is low, the failure life is short, and the desired reliability cannot be improved. On the other hand, when the molar amount of MgO exceeds 3.0 parts by mole with respect to 100 parts by mole of the Ti component, the temperature characteristics of the capacitance deteriorates, the specific resistance decreases, and the failure life is shortened. Reliability cannot be secured.
そこで、本実施の形態では、MgOの含有モル量をTi成分100モル部に対し0.05〜3.0モル部としている。   Therefore, in the present embodiment, the content molar amount of MgO is 0.05 to 3.0 mol parts with respect to 100 mol parts of the Ti component.
(7)Rの含有モル量
は誘電体セラミックの特性向上や信頼性向上に寄与することができるが、Rの含有モル量がTi成分100モル部に対し0.05モル部未満の場合は、故障寿命が短く、所望の信頼性向上を図ることができない。一方、Rの含有モル量がTi成分100モル部に対し2.5モル部を超えると、静電容量の温度特性が悪化する。
(7) R x O y molar amount R x O y of it can contribute to enhancing properties improved and reliability of the dielectric ceramic, with respect to molar amount of Ti component 100 moles of R x O y When the amount is less than 0.05 mol part, the failure life is short and the desired reliability cannot be improved. On the other hand, when the molar content of R x O y exceeds 2.5 mol parts with respect to 100 mol parts of the Ti component, the temperature characteristics of the capacitance deteriorate.
そこで、本実施の形態では、Rの含有モル量をTi成分100モル部に対し0.05〜2.5モル部としている。 Therefore, in the present embodiment, the content molar amount of R x O y is set to 0.05 to 2.5 mole parts with respect to 100 mole parts of the Ti component.
そして、このようなRとしては、La、CeO、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、及びLuの中から選択された少なくとも1種以上を使用することができる。 And, as such R x O y, La 2 O 3, CeO 2, Nd 2 O 3, Sm 2 O 3, Eu 2 O 3, Gd 2 O 3, Tb 2 O 3, Dy 2 O 3, At least one selected from Ho 2 O 3 , Er 2 O 3 , Tm 2 O 3 , Yb 2 O 3 , and Lu 2 O 3 can be used.
次に、上記誘電体セラミックの製造方法を説明する。   Next, a method for manufacturing the dielectric ceramic will be described.
まず、セラミック素原料として、Ca化合物、及び平均粒径が約10nmの超微粒のTi化合物及びBa化合物を用意した。そして、AサイトとBサイトの配合モル比mが0.998〜1.020、Ca成分の含有モル量がTi成分100モル部に対し0〜15モル部となるように前記セラミック素原料を秤量し、これら秤量物をPSZ(Partially Stabilized Zirconia:部分安定化ジルコニア)ボール等の粉砕媒体及び純水と共にボールミルに投入し、十分に湿式で混合粉砕し、乾燥させた後、950℃以上の温度で所定時間、熱処理を施し、これにより平均粒径0.1〜0.2μmの(Ba、Ca)TiOで表される高結晶化度の主成分を作製する。 First, as a ceramic raw material, a Ca compound and ultrafine Ti compound and Ba compound having an average particle diameter of about 10 nm were prepared. Then, the ceramic raw material is weighed so that the mixing molar ratio m of the A site and the B site is 0.998 to 1.020, and the content molar amount of the Ca component is 0 to 15 mol parts with respect to 100 mol parts of the Ti component. Then, these weighed materials are put into a ball mill together with grinding media such as PSZ (Partially Stabilized Zirconia) balls and pure water, mixed and pulverized sufficiently with wet, dried, and then at a temperature of 950 ° C. or higher. A heat treatment is performed for a predetermined time, whereby a high crystallinity main component represented by (Ba, Ca) m TiO 3 having an average particle diameter of 0.1 to 0.2 μm is produced.
尚、主成分である(Ba,Ca)TiOの結晶化度を高めたのは、後述するSiO−V混晶物を主成分に添加した場合にV成分が主成分に固溶し難くするためである。 Note that the crystallinity of the main component (Ba, Ca) m TiO 3 is increased when the SiO 2 —V 2 O 5 mixed crystal described later is added to the main component. This is to make it difficult to dissolve.
ここで、主成分(Ba,Ca)TiOの結晶化度は、例えば、結晶粒子のX線強度の特定結晶面(hkl)における半値幅ΔHを計測することにより確認することができる。 Here, the crystallinity of the main component (Ba, Ca) m TiO 3 can be confirmed, for example, by measuring the half-value width ΔH on the specific crystal plane (hkl) of the X-ray intensity of the crystal particles.
図1はX線回折スペクトルを模式的に示した図であり、横軸は回折角2θ、縦軸はX線強度(cps)を示している。   FIG. 1 is a diagram schematically showing an X-ray diffraction spectrum, where the horizontal axis indicates the diffraction angle 2θ and the vertical axis indicates the X-ray intensity (cps).
すなわち、X線強度のピークが急峻である程、結晶粒子の結晶性が高いことから、主成分の高さHの1/2に相当する半値幅ΔH(°)を求めることにより、主成分の結晶化度を評価することができる。   That is, the sharper the peak of the X-ray intensity, the higher the crystallinity of the crystal particles. Therefore, by obtaining a half-value width ΔH (°) corresponding to ½ of the height H of the main component, Crystallinity can be evaluated.
次に、SiO及びVを用意し、誘電体セラミック中におけるSiO及びVの含有モル量がTi成分100モル部に対しそれぞれ0.5〜8.0モル部及び0.02〜1.0モル部となるように秤量する。次いで、これら秤量物を粉砕媒体、エタノールやトルエン等の有機溶剤と共にボールミルに投入し、ボールミル内で十分に湿式で混合粉砕した後、乾燥させて配合物を得る。次に、この配合物を、温度1000℃で2時間熱処理を施し、溶融させて溶融物とした後、該溶融物を液体窒素(−196℃)に投入して急冷し、固化物を作製する。そしてこの後、この固化物を、再度、粉砕媒体及び前記有機溶剤と共にボールミルに投入し、該ボールミル内で十分に混合粉砕した後、乾燥させ、SiO−V混晶物を作製する。 Next, SiO 2 and V 2 O 5 are prepared, and the content molar amounts of SiO 2 and V 2 O 5 in the dielectric ceramic are 0.5 to 8.0 mole parts and 0 parts per 100 mole parts of the Ti component, respectively. Weigh out to 02-1.0 mol parts. Next, these weighed products are put into a ball mill together with a grinding medium and an organic solvent such as ethanol and toluene, mixed and pulverized sufficiently in a ball mill, and then dried to obtain a blend. Next, after heat-treating this blend at a temperature of 1000 ° C. for 2 hours to melt it into a melt, the melt is poured into liquid nitrogen (−196 ° C.) and rapidly cooled to produce a solidified product. . Thereafter, the solidified product is again put into a ball mill together with the grinding medium and the organic solvent, sufficiently mixed and ground in the ball mill, and then dried to produce a SiO 2 —V 2 O 5 mixed crystal. .
このようにSiO−V混晶物を得ることにより、微細なV組織がSiO組織に取り込まれた構造とすることができ、これにより誘電体セラミック中でV成分を結晶粒界に均一に分散させ、かつV成分の主成分内部への固溶をし難くしている。 Thus, by obtaining a SiO 2 —V 2 O 5 mixed crystal, it is possible to obtain a structure in which a fine V 2 O 5 structure is incorporated into the SiO 2 structure. It is made to disperse | distribute uniformly to a crystal grain boundary, and makes it difficult to carry out the solid solution inside the main component of V component.
次に、その他の添加成分としてMg化合物、Mn化合物、及び特定希土類元素R(ただし、RはY、La、Ce、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、及びLuの中から選択された1種以上)を含有した化合物を用意する。   Next, as other additive components, Mg compound, Mn compound, and specific rare earth element R (where R is Y, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, And one or more selected from Lu).
次いで、上記主成分、上記SiO−V混晶物、及び上記各添加成分を、Ti成分(主成分)100モル部に対し、SiOが0.5〜8.0モル部、Vが0.02〜1.0モル部、MnOが0.01〜5.0モル部、MgOが0.05〜3.0モル部、及びRが0.05〜2.5モル部となるように秤量し、該秤量物を粉砕媒体及び溶媒と共に混合し、配合物を作製する。 Next, the main component, the SiO 2 —V 2 O 5 mixed crystal, and each additive component are added in an amount of 0.5 to 8.0 mol parts of SiO 2 with respect to 100 mol parts of the Ti component (main component), V 2 O 5 is from 0.02 to 1.0 molar parts, MnO is 0.01 to 5.0 molar parts, MgO is 0.05 to 3.0 molar parts, and R x O y is 0.05 to 2 .Weigh out to 5 mole parts and mix the weighed material with grinding media and solvent to make a blend.
そして、この配合物が、後述するように積層セラミックコンデンサの製造過程で焼成処理に付され、本発明の誘電体セラミックとなる。   Then, as will be described later, this compound is subjected to a firing process in the manufacturing process of the multilayer ceramic capacitor, and becomes the dielectric ceramic of the present invention.
図2は本発明に係る誘電体セラミックを使用して製造された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した断面図である。   FIG. 2 is a cross-sectional view schematically showing an embodiment of a multilayer ceramic capacitor manufactured using a dielectric ceramic according to the present invention.
該積層セラミックコンデンサは、本発明の誘電体セラミックからなるセラミック焼結体1に内部電極2(2a〜2f)が埋設されると共に、該セラミック焼結体1の両端部には外部電極3a、3bが形成され、さらに該外部電極3a、3bの表面には第1のめっき皮膜4a、4b及び第2のめっき皮膜5a、5bが形成されている。   In the multilayer ceramic capacitor, internal electrodes 2 (2a to 2f) are embedded in a ceramic sintered body 1 made of a dielectric ceramic of the present invention, and external electrodes 3a and 3b are disposed at both ends of the ceramic sintered body 1. Further, first plating films 4a and 4b and second plating films 5a and 5b are formed on the surfaces of the external electrodes 3a and 3b.
すなわち、セラミック焼結体1は、複数の誘電体セラミック層1a〜1gの積層焼結体からなり、また、誘電体セラミック層1a〜1gと内部電極2a〜2fとが交互に積層された構造とされ、内部電極2a、2c、2eは外部電極3aと電気的に接続され、内部電極2b、2d、2fは外部電極3bと電気的に接続されている。そして、内部電極2a、2c、2eと内部電極2b、2d、2fとの対向面間で静電容量を形成している。   That is, the ceramic sintered body 1 is composed of a laminated sintered body of a plurality of dielectric ceramic layers 1a to 1g, and has a structure in which the dielectric ceramic layers 1a to 1g and the internal electrodes 2a to 2f are alternately laminated. The internal electrodes 2a, 2c, and 2e are electrically connected to the external electrode 3a, and the internal electrodes 2b, 2d, and 2f are electrically connected to the external electrode 3b. A capacitance is formed between the opposing surfaces of the internal electrodes 2a, 2c, and 2e and the internal electrodes 2b, 2d, and 2f.
上記積層セラミックコンデンサは、上記配合物を使用して以下のような方法で製造される。   The multilayer ceramic capacitor is manufactured by the following method using the compound.
すなわち、上記配合物を有機バインダや有機溶剤、粉砕媒体と共にボールミルに投入して湿式混合し、セラミックスラリーを作製し、ドクターブレード法等によりセラミックスラリーに成形加工を施し、焼成後の厚みが1μm程度又はそれ以下となるようにセラミックグリーンシートを作製する。   That is, the above compound is put into a ball mill together with an organic binder, an organic solvent, and a grinding medium and wet mixed to produce a ceramic slurry. The ceramic slurry is molded by a doctor blade method or the like, and the thickness after firing is about 1 μm. Or a ceramic green sheet is produced so that it may become less.
次いで、内部電極用導電性ペーストを使用してセラミックグリーンシート上にスクリーン印刷を施し、前記セラミックグリーンシートの表面に所定パターンの導電膜を形成する。   Next, screen printing is performed on the ceramic green sheet using the internal electrode conductive paste, and a conductive film having a predetermined pattern is formed on the surface of the ceramic green sheet.
尚、内部電極用導電性ペーストに含有される導電性材料としては、特に限定されるものではないが、低コスト化の観点からは、Ni、Cuやこれら合金を主成分とした卑金属材料を使用するのが好ましい。   The conductive material contained in the internal electrode conductive paste is not particularly limited, but from the viewpoint of cost reduction, a base metal material mainly composed of Ni, Cu or an alloy thereof is used. It is preferable to do this.
次いで、導電膜が形成されたセラミックグリーンシートを所定方向に複数枚積層し、導電膜の形成されていないセラミックグリーンシートで挟持し、圧着し、所定寸法に切断してセラミック積層体を作製する。そしてこの後、温度300〜500℃で脱バインダ処理を行ない、さらに、酸素分圧が10-9〜10-12MPaに制御されたH−N−HOガスからなる還元性雰囲気下、温度1100〜1300℃で約2時間焼成処理を行なう。これにより導電膜とセラミック材とが共焼結され、内部電極2が埋設されたセラミック焼結体1が得られる。 Next, a plurality of ceramic green sheets on which a conductive film is formed are laminated in a predetermined direction, sandwiched between ceramic green sheets on which a conductive film is not formed, pressure-bonded, and cut into predetermined dimensions to produce a ceramic laminate. Thereafter, the binder removal treatment is performed at a temperature of 300 to 500 ° C., and further, in a reducing atmosphere composed of H 2 —N 2 —H 2 O gas whose oxygen partial pressure is controlled to 10 −9 to 10 −12 MPa. The baking treatment is performed at a temperature of 1100 to 1300 ° C. for about 2 hours. Thereby, the conductive film and the ceramic material are co-sintered, and the ceramic sintered body 1 in which the internal electrode 2 is embedded is obtained.
次に、セラミック焼結体1の両端面に外部電極用導電性ペーストを塗布し、焼付処理を行い、外部電極3a、3bを形成する。   Next, a conductive paste for external electrodes is applied to both end faces of the ceramic sintered body 1 and subjected to a baking treatment to form external electrodes 3a and 3b.
尚、外部電極用導電性ペーストに含有される導電性材料についても、特に限定されるものではないが、低コスト化の観点から、AgやCu、或いはこれらの合金を主成分とした材料を使用するのが好ましい。   The conductive material contained in the conductive paste for external electrodes is not particularly limited, but from the viewpoint of cost reduction, a material mainly composed of Ag, Cu, or an alloy thereof is used. It is preferable to do this.
また、外部電極3a、3bの形成方法としては、セラミック積層体の両端面に外部電極用導電性ペーストを塗布した後、セラミック積層体と同時に焼成処理を施すようにしてもよい。   In addition, as a method of forming the external electrodes 3a and 3b, an external electrode conductive paste may be applied to both end faces of the ceramic laminate, and then fired simultaneously with the ceramic laminate.
そして、最後に、電解めっきを施して外部電極3a、3bの表面にNi、Cu、Ni−Cu合金等からなる第1のめっき皮膜4a、4bを形成し、さらに該第1のめっき皮膜4a、4bの表面にはんだやスズ等からなる第2のめっき皮膜5a、5bを形成し、これにより積層セラミックコンデンサが製造される。   Finally, electrolytic plating is performed to form first plating films 4a and 4b made of Ni, Cu, Ni—Cu alloy or the like on the surfaces of the external electrodes 3a and 3b, and further, the first plating film 4a, Second plating films 5a and 5b made of solder, tin or the like are formed on the surface of 4b, whereby a multilayer ceramic capacitor is manufactured.
このように本積層セラミックコンデンサは、上述した誘電体セラミックを使用して製造されているので、誘電体セラミック層1a〜1gが1μm以下、例えば0.7μm程度に薄層化されても高比誘電率を有し、低誘電損失で、静電容量の温度特性を損なうことなく、静電容量のDCバイアス特性も良好で、絶縁性や高温負荷時における故障寿命が長く、信頼性の優れた積層セラミックコンデンサを容易に得ることができる。   Thus, since this multilayer ceramic capacitor is manufactured using the above-mentioned dielectric ceramic, even if the dielectric ceramic layers 1a to 1g are thinned to 1 μm or less, for example, about 0.7 μm, a high dielectric constant Highly reliable stacking with high dielectric constant, low dielectric loss, good capacitance DC bias characteristics without losing capacitance temperature characteristics, long insulation life and long failure life under high temperature load A ceramic capacitor can be easily obtained.
尚、本発明は上記実施の形態に限定されるものではない。例えば、上記実施の形態では、10nm程度の超微粒のセラミック素原料を使用し、固相法により高結晶化度を有する主成分(Ba,Ca)TiOを作製したが、熱処理条件を調整することによっても結晶性を高めることができ、加水分解法や水熱合成法等他の合成法によっても所望の高結晶化度を有する主成分を得ることが可能である。 The present invention is not limited to the above embodiment. For example, in the above embodiment, a main component (Ba, Ca) m TiO 3 having a high crystallinity was produced by a solid phase method using an ultrafine ceramic raw material of about 10 nm, but the heat treatment conditions were adjusted. By doing so, the crystallinity can be increased, and a main component having a desired high crystallinity can be obtained by other synthesis methods such as a hydrolysis method and a hydrothermal synthesis method.
また、Ba化合物、Ca化合物、Ti化合物についても、炭酸塩や酸化物、硝酸塩、水酸化物、有機酸塩、アルコキシド、キレート化合物等、合成反応の形態に応じて適宜選択することができる。   Also, the Ba compound, Ca compound, and Ti compound can be appropriately selected according to the form of the synthetic reaction, such as carbonate, oxide, nitrate, hydroxide, organic acid salt, alkoxide, chelate compound, and the like.
また、上述した積層セラミックコンデンサの製造過程で、Al、Sr、Zr、Fe、Hf、Na、Co等が不純物として混入し、結晶粒子内や結晶粒界に存在するおそれがあるが、コンデンサの電気特性に影響を及ぼすものではない。   Further, in the above-described manufacturing process of the multilayer ceramic capacitor, Al, Sr, Zr, Fe, Hf, Na, Co, etc. may be mixed as impurities and exist in the crystal grains or in the crystal grain boundaries. It does not affect the characteristics.
また、積層セラミックコンデンサの焼成処理で内部電極成分が結晶粒子内や結晶粒界に拡散するおそれがあるが、この場合もコンデンサの電気特性に影響を及ぼすことはない。   Further, there is a possibility that the internal electrode component diffuses into the crystal grains or the crystal grain boundaries in the firing process of the multilayer ceramic capacitor, but this also does not affect the electrical characteristics of the capacitor.
〔主成分の作製〕
まず、セラミック素原料として、高純度のCaCO、平均粒径が10〜50nmのTiO及びBaCOを用意し、表1に示すような組成を有するようにこれらセラミック素原料を秤量した。そして、これら秤量物をPSZボール及び純水と共にボールミルに投入し、24時間湿式で混合粉砕し、乾燥させた後、温度1000℃で2時間、熱処理を施し、平均粒径0.1〜0.2μmの(Ba、Ca)TiOで表される主成分A〜Uを作製した。
[Production of main components]
First, high-purity CaCO 3 , TiO 2 having an average particle diameter of 10 to 50 nm and BaCO 3 were prepared as ceramic raw materials, and these ceramic raw materials were weighed so as to have the compositions shown in Table 1. Then, these weighed materials are put into a ball mill together with PSZ balls and pure water, mixed and pulverized in a wet manner for 24 hours, dried, and then heat treated at a temperature of 1000 ° C. for 2 hours to obtain an average particle size of 0.1 to 0.00. Main components A to U represented by 2 μm of (Ba, Ca) m TiO 3 were prepared.
次に、これら主成分A〜Uの結晶面(111)におけるX線スペクトルをXRD(X-Ray Diffraction:X線回折装置CuKα)で測定し、半値幅ΔH(°)を求めた。   Next, the X-ray spectrum in the crystal plane (111) of these main components A to U was measured by XRD (X-Ray Diffraction: X-ray diffractometer CuKα), and the half-value width ΔH (°) was obtained.
表1は主成分A〜Uの各成分の配合比率及び半値幅ΔH(°)を示している。   Table 1 shows the blending ratio and half-value width ΔH (°) of each component of the main components A to U.
主成分AはCaの含有モル量がTi成分100モル部に対し15.5モル部であり、15モル部を超えているため、本発明範囲外の組成である。主成分BはAサイトとBサイトの配合モル比mが0.997であって0.998未満であり、また主成分Cは前記配合モル比mが1.021であって1.020を超えており、いずれも本発明範囲外の組成である。 The main component A is a composition outside the scope of the present invention because the molar content of Ca is 15.5 mol parts with respect to 100 mol parts of the Ti component and exceeds 15 mol parts. The main component B has a blending molar ratio m of A site and B site of 0.997 and less than 0.998, and the main component C has a blending molar ratio m of 1.021 and exceeding 1.020. Both are compositions outside the scope of the present invention.
これに対し主成分D〜Uは前記配合モル比mが0.998〜1.020の範囲にあり、またCaの含有モル量はTi成分100モル部に対し0〜15モル部の範囲にあり、いずれも本発明範囲内の組成を有している。   On the other hand, the main components D to U have a blending molar ratio m in the range of 0.998 to 1.020, and the molar content of Ca is in the range of 0 to 15 parts by mole with respect to 100 parts by mole of the Ti component. These have compositions within the scope of the present invention.
また、主成分A〜Sは、平均粒径が約10nmの超微粒のTiO及びBaCOを使用して作製したのに対し、主成分T、Uは、平均粒径が約50nmの若干粗いTiO及びBaCOを使用して作製した。このため、主成分T、Uは半値幅ΔHが0.36°〜0.42°と大きくなって0.35°を超えてしまい、結晶化度が低くなったのに対し、主成分A〜Sは半値幅ΔHが0.28°〜0.32°と小さく0.35°未満であり、高結晶化度を有する主成分を得ることができた。 The main components A to S were prepared using ultrafine TiO 2 and BaCO 3 with an average particle size of about 10 nm, whereas the main components T and U were slightly coarse with an average particle size of about 50 nm. Made using TiO 2 and BaCO 3 . For this reason, the main components T and U have a half-value width ΔH of 0.36 ° to 0.42 °, which exceeds 0.35 °, and the degree of crystallinity is low. S had a half width ΔH as small as 0.28 ° to 0.32 ° and less than 0.35 °, and a main component having high crystallinity could be obtained.
〔積層セラミックコンデンサの作製〕
(試料番号1〜5、7〜15、18〜83)
SiO及びVを用意し、これらSiO及びVの含有モル量がTi成分100モル部に対し、表2〜4に示す配合比率となるように秤量し、これら秤量物をPSZボールや有機溶剤としてのエタノールと共にボールミルに投入し、該ボールミル内で36時間湿式で混合粉砕した後、乾燥させて配合物を得た。次いで、この配合物を、温度1000℃で2時間熱処理を施し、溶融させて溶融物とした後、該溶融物を液体窒素(−196℃)に投入して急冷し、固化物を作製した。そしてこの後、この固化物を、再度、PSZボール及びエタノールと共にボールミルに投入し、該ボールミル内で24時間混合粉砕した後、乾燥させ、SiO−V混晶物を作製した。
[Production of multilayer ceramic capacitors]
(Sample Nos. 1-5, 7-15, 18-83)
SiO 2 and V 2 O 5 were prepared and weighed so that the molar content of these SiO 2 and V 2 O 5 was the mixing ratio shown in Tables 2 to 4 with respect to 100 mol parts of the Ti component. Was put into a ball mill together with PSZ balls and ethanol as an organic solvent, mixed and pulverized in the ball mill for 36 hours by wet, and then dried to obtain a blend. Next, the blend was heat-treated at a temperature of 1000 ° C. for 2 hours to melt it to obtain a melt, and then the melt was poured into liquid nitrogen (−196 ° C.) to rapidly cool to produce a solidified product. Thereafter, the solidified product was again put into a ball mill together with PSZ balls and ethanol, mixed and ground in the ball mill for 24 hours, and then dried to prepare a SiO 2 —V 2 O 5 mixed crystal.
次に、他の添加成分としてMgCO、MnCO、及びR(ただし、RはY、La、CeO、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、又はLu)の各粉末を用意した。そして、上記主成分、SiO−V混晶物、及び上記各添加成分を表2〜4に示す配合比率となるように秤量し、該秤量物をPSZボール及び純水と共にボールミルに投入し、8時間湿式で混合粉砕し、配合物を得た。 Next, MgCO 3 , MnCO 3 , and R x O y as other additive components (where R x O y is Y 2 O 3 , La 2 O 3 , CeO 2 , Nd 2 O 3 , Sm 2 O 3 , Eu 2 O 3 , Gd 2 O 3 , Tb 2 O 3 , Dy 2 O 3 , Ho 2 O 3 , Er 2 O 3 , Tm 2 O 3 , Yb 2 O 3 , or Lu 2 O 3 ) Prepared. Then, the main component, SiO 2 —V 2 O 5 mixed crystal, and each additive component were weighed so as to have a blending ratio shown in Tables 2 to 4, and the weighed product was put into a ball mill together with PSZ balls and pure water. The mixture was mixed and pulverized by wet for 8 hours to obtain a blend.
次に、該配合物に有機バインダとしてのポリビニルブチラール樹脂及び有機溶剤としてのエタノールを添加し、ボールミル内で湿式混合し、これによりセラミックスラリーを得た。そしてこの後、ドクターブレード法を使用してセラミックスラリーに成形加工を施し、厚みが0.85μmの矩形状のセラミックグリーンシートを作製した。   Next, polyvinyl butyral resin as an organic binder and ethanol as an organic solvent were added to the blend, and wet-mixed in a ball mill to obtain a ceramic slurry. Thereafter, the ceramic slurry was molded using a doctor blade method to produce a rectangular ceramic green sheet having a thickness of 0.85 μm.
次いで、Niを主成分とした内部電極用導電性ペーストを用意し、該内部電極用導電性ペーストを使用して前記セラミックグリーンシートにスクリーン印刷を施し、内部電極となるべき導電膜をセラミックグリーンシートの表面に形成した。   Next, an internal electrode conductive paste containing Ni as a main component is prepared, and the ceramic green sheet is screen-printed using the internal electrode conductive paste, and the conductive film to be the internal electrode is formed into the ceramic green sheet. Formed on the surface.
次いで、導電膜が形成されたセラミックグリーンシートを所定方向に複数枚積層し、導電膜の形成されていないセラミックグリーンシートで挟持し、圧着し、所定寸法に切断してセラミック積層体を作製した。そしてこの後、窒素雰囲気下、温度350℃で脱バインダ処理を行ない、さらに、酸素分圧が10-10MPaに制御されたH−N−HOガスからなる還元性雰囲気下、温度1100〜1250℃で2時間焼成処理を施し、内部電極が埋設されたセラミック焼結体(誘電体セラミック)を作製した。 Next, a plurality of ceramic green sheets on which a conductive film was formed were laminated in a predetermined direction, sandwiched between ceramic green sheets on which a conductive film was not formed, pressure-bonded, and cut into predetermined dimensions to produce a ceramic laminate. Thereafter, the binder removal treatment is performed at a temperature of 350 ° C. in a nitrogen atmosphere, and further, the temperature is reduced in a reducing atmosphere composed of H 2 —N 2 —H 2 O gas whose oxygen partial pressure is controlled to 10 −10 MPa. A firing process was performed at 1100 to 1250 ° C. for 2 hours to produce a ceramic sintered body (dielectric ceramic) in which internal electrodes were embedded.
その後、B−LiO−SiO−BaO系ガラス成分を含有した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、窒素雰囲気下、温度600℃で焼付処理を施し、外部電極を形成し、試料番号1〜5、7〜15、18〜83の積層セラミックコンデンサを作製した。 Thereafter, a conductive paste for external electrodes mainly composed of Ag containing a B 2 O 3 —Li 2 O—SiO 2 —BaO-based glass component is prepared, and the conductive paste for external electrodes is used as a ceramic sintered body. It apply | coated to both end surfaces, the baking process was performed at the temperature of 600 degreeC in nitrogen atmosphere, the external electrode was formed, and the multilayer ceramic capacitor of sample numbers 1-5, 7-15, and 18-83 was produced.
尚、各積層セラミックコンデンサは、外形寸法が、縦2.1mm、横1.3mm、厚み2.0mm、内部電極間に介在する誘電体セラミック層の厚みは0.7μmであった。また、有効誘電体セラミック層の積層数は50であり、1層あたりの対向電極面積は1.4×10-6であった。 Each multilayer ceramic capacitor had outer dimensions of 2.1 mm in length, 1.3 mm in width, 2.0 mm in thickness, and the thickness of the dielectric ceramic layer interposed between the internal electrodes was 0.7 μm. The number of effective dielectric ceramic layers stacked was 50, and the counter electrode area per layer was 1.4 × 10 −6 m 2 .
(試料番号6、16、17)
主成分Dを作製した後、SiO、V、MgCO、MnCO、及びYの各粉末を用意した。次いで、Ti成分(主成分D)100モル部に対し表2の配合比率となるようにこれら各粉末及び主成分Dを秤量し、配合物を得た。
(Sample numbers 6, 16, 17)
After producing the main component D, SiO 2 , V 2 O 5 , MgCO 3 , MnCO 3 , and Y 2 O 3 powders were prepared. Next, each of these powders and the main component D was weighed so as to have the mixing ratio shown in Table 2 with respect to 100 mol parts of the Ti component (main component D) to obtain a blend.
そしてその後は、上述と同様の方法・手順でセラミックスラリー→セラミックグリーンシート→セラミック積層体→セラミック焼結体を順次作製し、試料番号6、16、17の積層セラミックコンデンサを作製した。   After that, ceramic slurry → ceramic green sheet → ceramic laminate → ceramic sintered body was sequentially produced by the same method and procedure as described above, and multilayer ceramic capacitors of sample numbers 6, 16, and 17 were produced.
(各試料の成分分析)
試料番号1〜83について、TEM(Transmission Electron Microscope:透過型電子顕微鏡)で観察された結晶粒界及び結晶粒子を、EELS(Electron Energy Loss Spectroscopy:電子線エネルギー損失分光法)で分析し、結晶粒界及び結晶粒子におけるTi成分100モル部に対するV成分量を測定した。
(Component analysis of each sample)
Sample Nos. 1 to 83 were analyzed by EELS (Electron Energy Loss Spectroscopy) for crystal grain boundaries and crystal particles observed by TEM (Transmission Electron Microscope). The amount of V component with respect to 100 mole parts of Ti component in the boundary and crystal grains was measured.
尚、結晶粒子内部ではV成分の検出確率を高める必要があることから、電子線プローブ径を50nmとし、結晶粒界では分解能を高める必要があることから電子線プローブ径を1nm未満とした。   Since it is necessary to increase the detection probability of the V component inside the crystal grain, the electron beam probe diameter is set to 50 nm, and since it is necessary to increase the resolution at the crystal grain boundary, the electron beam probe diameter is set to less than 1 nm.
また、結晶粒子及び結晶粒界における分析点は各試料毎に各々20点とし、結晶粒子内部については、結晶粒界から少なくとも5nm以上離れた点を分析点とした。   The analysis points in the crystal grains and the crystal grain boundaries were 20 points for each sample, and for the inside of the crystal grains, the analysis points were at least 5 nm away from the crystal grain boundaries.
結晶粒界については、Ti成分100モル部に対するV成分の含有モル量が誘電体セラミック中のV成分の総含有モル量の2倍以上となる分析点を計数し、全分析点に対する比率(以下、本実施例で「粒界V」という。)を算出し、V成分の結晶粒界中での均一分散性を評価した。   For the grain boundaries, the number of analysis points where the content molar amount of the V component with respect to 100 mol parts of the Ti component is at least twice the total content of the V component in the dielectric ceramic is counted, and the ratio to the total analysis points (hereinafter, In this example, it is referred to as “grain boundary V”), and the uniform dispersibility of the V component in the crystal grain boundary was evaluated.
結晶粒子については、V成分の含有モル量がTi成分100モル部に対し0.04モル部以上となる分析点を計数し、全分析点に対する比率(以下、本実施例で「粒内V」という。)を算出し、V成分の主成分への難固溶性を評価した。   For crystal grains, the number of analysis points at which the content of the V component is 0.04 mol part or more with respect to 100 mol parts of the Ti component is counted and the ratio to the total analysis points (hereinafter referred to as “intragranular V” in this example) And the poor solubility of the V component in the main component was evaluated.
(各試料の特性評価)
自動ブリッジ式測定器を使用し、周波数120Hz、実効電圧0.35Vrms、温度25℃の条件で、電界強度0.5V/μmの交流電圧を各試料に印加し、静電容量C及び誘電損失tanδを測定し、得られた静電容量Cと試料寸法とから比誘電率εrを算出した。
(Characteristic evaluation of each sample)
Using an automatic bridge-type measuring device, an AC voltage with an electric field strength of 0.5 V / μm was applied to each sample under the conditions of a frequency of 120 Hz, an effective voltage of 0.35 Vrms, and a temperature of 25 ° C., and the capacitance C and dielectric loss tanδ. Was measured, and the relative dielectric constant εr was calculated from the obtained capacitance C and the sample dimensions.
静電容量の温度特性及びDCバイアス特性については温度変化に対する容量変化率(以下、「温度変化率」という。)とDCバイアスを印加したときの容量変化率(以下、「DC変化率」という。)を測定し、各々特性を評価した。   The capacitance temperature characteristics and DC bias characteristics are referred to as a capacitance change rate with respect to temperature change (hereinafter referred to as “temperature change rate”) and a capacitance change rate when a DC bias is applied (hereinafter referred to as “DC change rate”). ) Was measured, and each characteristic was evaluated.
すなわち、温度変化率については、JIS(日本工業規格)で規定するB特性を満足する必要があることから、+20℃での静電容量を基準とした−25℃から+85℃の範囲における温度変化率(ΔC/C20)を測定した。 That is, the temperature change rate needs to satisfy the B characteristic defined in JIS (Japanese Industrial Standard), so the temperature change in the range of -25 ° C to + 85 ° C with reference to the capacitance at + 20 ° C. The rate (ΔC / C 20 ) was measured.
また、DC変化率については、自動ブリッジ式測定器により、周波数120Hz、実効電圧0.35Vrms、温度25℃の条件で、電界強度0.5V/μmの交流電圧が印加された各試料に対し、2.5V/μmの直流電圧を印加して静電容量を測定し、直流電圧の非印加時に対する静電容量の変化率を求めた。   Regarding the DC change rate, each sample to which an AC voltage having an electric field strength of 0.5 V / μm was applied under the conditions of a frequency of 120 Hz, an effective voltage of 0.35 Vrms, and a temperature of 25 ° C. by an automatic bridge type measuring device. The capacitance was measured by applying a DC voltage of 2.5 V / μm, and the change rate of the capacitance with respect to the time when no DC voltage was applied was determined.
また、絶縁抵抗計を使用し、温度25℃で7Vの直流電圧を60秒間印加したときの絶縁抵抗Rを測定し、得られた絶縁抵抗Rに基づいて比抵抗logρを算出した。   In addition, an insulation resistance meter was used to measure the insulation resistance R when a DC voltage of 7 V was applied for 60 seconds at a temperature of 25 ° C., and the specific resistance logρ was calculated based on the obtained insulation resistance R.
また、高温負荷試験を行い、高温負荷時の平均故障寿命を求めた。すなわち、試料番号1〜83の試料各20個について、温度150℃の高温下、7Vの直流電圧を印加し、絶縁抵抗Rの経時変化を測定し、絶縁抵抗Rが10Ωに低下した時点を故障と判断し、その平均値を算出して平均故障寿命を求めた。 In addition, a high temperature load test was conducted to determine the average failure life at high temperature load. That is, for each of the 20 samples Nos. 1 to 83, a 7V DC voltage was applied at a high temperature of 150 ° C., the change over time in the insulation resistance R was measured, and when the insulation resistance R dropped to 10 5 Ω Was determined to be a failure, and an average value was calculated to obtain an average failure life.
表2〜4は試料番号1〜83の組成成分及び焼成温度を示し、表5〜7は各測定結果を示している。尚、表5〜7中、温度変化率は+85℃のときの温度変化率ΔC85℃のみを掲載している。 Tables 2 to 4 show the composition components and firing temperatures of sample numbers 1 to 83, and Tables 5 to 7 show the measurement results. In Tables 5 to 7, only the temperature change rate ΔC 85 ° C. when the temperature change rate is + 85 ° C. is shown.
表2及び表5から明らかなように、試料番号1はCa成分の含有モル量がTi成分100モル部に対し15.5モル部とされた主成分Aを使用しており、Ca成分の含有モル量が過剰であるため、信頼性を確保することはできたものの、比誘電率εrが2210となって2500未満と低くなった。 As is apparent from Tables 2 and 5, Sample No. 1 uses the main component A in which the molar content of the Ca component is 15.5 mol parts with respect to 100 mol parts of the Ti component. Since the molar amount was excessive, reliability could be secured, but the relative dielectric constant εr was 2210, which was as low as 2500.
試料番号2は、配合モル比mが0.997とされた主成分Bを使用しており、配合モル比mが0.998未満であるため、比抵抗ρが107.2Ω・m(logρ:7.2)と低く、また、高温負荷試験を行った瞬間に故障が生じたため、平均故障寿命は測定できなかった。 Sample No. 2 uses the main component B having a blending molar ratio m of 0.997, and the blending molar ratio m is less than 0.998, so that the specific resistance ρ is 10 7.2 Ω · m (logρ: 7.2), and the failure occurred at the moment when the high temperature load test was performed, so the average failure life could not be measured.
試料番号3は、配合モル比mが1.021とされた主成分Cを使用しており、配合モル比mが1.020を超えているため、比誘電率εrが2180となって2500未満に低下し、また誘電損失tanδが10.5%となって10%を超えており、誘電特性が劣化することが分った。しかも、比抵抗ρが108.8Ω・m(logρ:8.8)であり1010.5Ω・m未満に低下し、平均故障寿命も5時間と短く、所望の信頼性を得るには程遠いことが分った。 Sample No. 3 uses the main component C having a blending molar ratio m of 1.021, and the blending molar ratio m exceeds 1.020, so that the relative dielectric constant εr is 2180 and less than 2500. It was also found that the dielectric loss tan δ was 10.5%, exceeding 10%, and the dielectric properties deteriorated. Moreover, the specific resistance ρ is 10 8.8 Ω · m (log ρ: 8.8), which is less than 10 10.5 Ω · m, the average failure life is as short as 5 hours, and it is far from obtaining the desired reliability. I understand.
試料番号4は、SiOの含有モル量がTi成分100モル部に対し0.045モル部であり、0.5モル部未満であるため、比誘電率εrが1850となって2500未満に低下し、また誘電損失tanδも12.5%となって10%を超えており、所望の誘電特性が得られないことが分った。しかも、比抵抗ρが109.8Ω・m(logρ:9.8)であり1010.5Ω・m未満に低下し、平均故障寿命も5時間と短く、所望の信頼性を得るには程遠いことが分った。 Sample No. 4 has a SiO 2 content of 0.045 mole part with respect to 100 mole parts of the Ti component and is less than 0.5 mole part, so that the relative dielectric constant εr is 1850 and falls below 2500. In addition, the dielectric loss tan δ was 12.5%, exceeding 10%, and it was found that the desired dielectric characteristics could not be obtained. Moreover, the specific resistance ρ is 10 9.8 Ω · m (log ρ: 9.8), which is less than 10 10.5 Ω · m, the average failure life is as short as 5 hours, and it is far from achieving the desired reliability. I understand.
試料番号5は、SiOの含有モル量がTi成分100モル部に対し8.20モル部であり、8.0モル部を超えているため、比誘電率εrが1970となって2500未満に低下し、温度変化率ΔC85℃も−10.7%となってB特性を満足せず、平均故障寿命も10時間と短く、所望の信頼性を得ることはできなかった。 Sample No. 5 has a SiO 2 content of 8.20 mole parts with respect to 100 mole parts of the Ti component, and exceeds 8.0 mole parts, so that the relative dielectric constant εr becomes 1970 and less than 2500. The temperature change rate ΔC 85 ° C. was −10.7%, the B characteristic was not satisfied, the average failure life was as short as 10 hours, and the desired reliability could not be obtained.
試料番号6は、誘電体セラミック中にVが含有されておらず、したがって粒界Vが存在しないため、平均故障寿命が30時間と短かく、所望の信頼性を確保することができなかった。これは、結晶粒界中にV成分が存在しないため、該結晶粒界に高い電界が印加されたためと思われる。 Sample No. 6 does not contain V 2 O 5 in the dielectric ceramic, and therefore there is no grain boundary V. Therefore, the average failure life is as short as 30 hours, and the desired reliability can be ensured. There wasn't. This is presumably because a high electric field was applied to the crystal grain boundary because no V component was present in the crystal grain boundary.
試料番号7は、Vの含有モル量がTi成分100モル部に対し1.05モル部であり、1.0モル部を超えているため、比誘電率εrが1980となって2500未満に低下し、高比誘電率を得ることができず、また温度変化率ΔC85℃も−11.5%となってB特性を満足せず、温度特性の劣化を招くことが分った。しかも比抵抗ρが1010.2Ω・m(logρ:10.2)となって1010.5Ω・m未満に低下し、平均故障寿命も5時間と短かく、所望の信頼性を得るには程遠いことが分った。 Sample No. 7 has a relative dielectric constant εr of 1980 and 2500 since the content molar amount of V 2 O 5 is 1.05 mol parts with respect to 100 mol parts of Ti component and exceeds 1.0 mol parts. It was found that the high relative dielectric constant could not be obtained, the temperature change rate ΔC 85 ° C. was −11.5%, and the B characteristic was not satisfied, leading to the deterioration of the temperature characteristic. . In addition, the specific resistance ρ is 10 10.2 Ω · m (log ρ: 10.2), which is reduced to less than 10 10.5 Ω · m, the average failure life is as short as 5 hours, and is far from achieving the desired reliability. I found out.
試料番号8は、MnOの含有モル量がTi成分100モル部に対し0.008モル部であり、0.01モル部未満であるため、比抵抗ρが107.5Ω・m(logρ:7.5)となって1010.5Ω・m未満に低下し、平均故障寿命も5時間と短く、この場合も所望の信頼性を得るには程遠いことが分った。 Sample No. 8 has a MnO content of 0.008 mol part with respect to 100 mol parts of the Ti component, and is less than 0.01 mol part, so that the specific resistance ρ is 10 7.5 Ω · m (log ρ: 7.5) and decreased to less than 10 10.5 Ω · m, the average failure life was as short as 5 hours, and it was found that this case is far from achieving the desired reliability.
試料番号9は、MnOの含有モル量がTi成分100モル部に対し5.200モル部であり、5.0モル部を超えているため、信頼性は確保できたものの、比誘電率εrが2420となって2500未満に低下し、また温度変化率ΔC85℃が−10.5%となって−10%を超えており、温度特性の悪化を招くことが分かった。 Sample No. 9 has a molar content of MnO of 5.200 mol parts with respect to 100 mol parts of Ti component and exceeds 5.0 mol parts. dropped below 2500 becomes 2420, and the temperature change rate [Delta] C 85 ° C. is above -10% becomes -10.5%, was found to lead to deterioration of the temperature characteristics.
試料番号10は、MgOの含有モル量がTi成分100モル部に対し0.045モル部であり、0.05モル部未満であるため、比抵抗ρが10.9.8Ω・m(logρ:9.8)となって1010.5Ω・m未満に低下し、平均故障寿命も5時間と短く、所望の信頼性が得られないことが分った。 Sample No. 10 has a MgO content of 0.045 mol parts with respect to 100 mol parts of the Ti component and less than 0.05 mol parts, so that the specific resistance ρ is 10.9.8 Ω · m (log ρ: 9 .8) and is reduced to less than 10 10.5 Ω · m, the average time to failure is short and 5 hours, it was found that the desired reliability can not be obtained.
試料番号11は、MgOの含有モル量がTi成分100モル部に対し3.20モル部であり、3.0モル部を超えているため、比抵抗ρが109.6Ω・m(logρ:9.6)となって1010.5Ω・m未満と低くなり、平均故障寿命も10時間と短く、所望の信頼性が得られないことが分った。 Sample No. 11 has a molar content of MgO of 3.20 mol parts with respect to 100 mol parts of Ti component and exceeds 3.0 mol parts, so that the specific resistance ρ is 10 9.6 Ω · m (log ρ: 9 .6) and turned in as low as less than 10 10.5 Omega · m, the average time to failure is short and 10 hours has been found that the desired reliability can not be obtained.
試料番号12は、RとしてのYの含有モル量がTi成分100モル部に対し0.04モル部であり、0.05モル部未満であるため、平均故障寿命が5時間と短く、信頼性を確保できないことが分った。 Sample No. 12 has an average failure life of 5 because the molar content of Y 2 O 3 as R x O y is 0.04 mol parts with respect to 100 mol parts of Ti component and less than 0.05 mol parts. It was found that the time was short and reliability could not be secured.
試料番号13は、Yの含有モル量がTi成分100モル部に対し2.60モル部であり、2.5モル部を超えているため、信頼性は確保できたものの、温度変化率Δ85℃が−11.1%となってB特性を満足せず、温度特性が悪化することが分った。 Sample No. 13 had a Y 2 O 3 molar content of 2.60 mol parts with respect to 100 mol parts of the Ti component, and exceeded 2.5 mol parts. It was found that the rate Δ85 ° C. was −11.1%, the B characteristic was not satisfied, and the temperature characteristic was deteriorated.
試料番号14は粒内Vが50%であり、5%を遥かに超えており、このため平均故障寿命が40時間と短く、所望の信頼性を確保できないことが分った。これは、試料番号14は、半値幅ΔHが0.36°と大きく、結晶性の低い主成分Tを使用しているため、V成分の主成分への固溶が促進されたためと思われる。   Sample No. 14 had an intragranular V of 50% and far exceeded 5%. Therefore, it was found that the average failure life was as short as 40 hours and the desired reliability could not be ensured. This is presumably because Sample No. 14 has a large half-value width ΔH of 0.36 ° and uses a main component T having low crystallinity, so that the solid solution of the V component into the main component is promoted.
試料番号15も、半値幅ΔHが0.42°と大きく、結晶性の低い主成分Uを使用していることから、試料番号14と同様、粒内Vが75%であり、5%を遥かに超えており、しかも、粒界Vも40%となって80%以下であり、したがって、V成分は結晶粒界に均一に分散することなくV成分の主成分への固溶がより一層促進され、その結果平均故障寿命が40時間と短く、所望の信頼性を確保できないことが分った。   Sample No. 15 also has a large half-value width ΔH of 0.42 ° and uses a main component U with low crystallinity, so that, similarly to Sample No. 14, the intragranular V is 75%, far exceeding 5%. In addition, the grain boundary V is 40% and is 80% or less. Therefore, the V component is not evenly dispersed in the crystal grain boundary, and the solid solution of the V component to the main component is further promoted. As a result, it has been found that the average failure life is as short as 40 hours, and the desired reliability cannot be ensured.
試料番号16、17は、SiO−V混晶物を作製せずに、SiO、Vを直接主成分に添加しているため、粒内Vは5%となってV成分の主成分への固溶は抑制されるものの、粒界Vは30〜50%となって80%以下となり、このため平均故障寿命が40時間と短く、所望の信頼性を確保できなかった。これはVを直接主成分に添加したため、微粒のV成分が凝集し、このためV成分を結晶粒界内で均一に分散させることができず、所望の信頼性を確保できなかったものと思われる。 In Sample Nos. 16 and 17, SiO 2 and V 2 O 5 were added directly to the main component without producing a SiO 2 —V 2 O 5 mixed crystal, so the intragranular V was 5%. Although the solid solution of the V component in the main component is suppressed, the grain boundary V is 30 to 50% and is 80% or less. Therefore, the average failure life is as short as 40 hours, and the desired reliability cannot be ensured. It was. This is because V 2 O 5 was added directly to the main component, so that the fine V component aggregated, and therefore the V component could not be uniformly dispersed within the crystal grain boundary, and the desired reliability could not be ensured. It seems to be.
これに対し表3、4、6、7から明らかなように、試料番号18〜83は、主成分中の配合モル比m、Ca成分の含有モル量、SiO、V、MnO、MgO、及びRが本発明の範囲内にあり、粒界Vが80%以上、粒内Vが5%以下であるので、比誘電率εrは2500以上、誘電損失tanδは10.0%以下となり、また温度変化率ΔC85℃はJISに規定するB特性を満足し、DC変化率も絶対値で25%以下に抑制でき、さらには比抵抗ρも25℃で1010.5Ω・m以上を確保でき、高温負荷時の平均故障寿命も100時間以上を確保できることが分った。 In contrast, as apparent from Table 3, 4, 6, 7, Sample No. 18 to 83, the content molar quantity of the molar amounts m, Ca component in the main component, SiO 2, V 2 O 5 , MnO, Since MgO and R x O y are within the scope of the present invention, the grain boundary V is 80% or more, and the grain V is 5% or less, the relative dielectric constant εr is 2500 or more, and the dielectric loss tanδ is 10.0. The temperature change rate ΔC 85 ° C satisfies the B characteristics specified in JIS, the DC change rate can be suppressed to 25% or less in absolute value, and the specific resistance ρ is 10 10.5 Ω · m at 25 ° C. It has been found that the above can be ensured, and the average failure life at high temperature load can be ensured to be 100 hours or more.
すなわち、試料番号18〜83によれば、誘電体セラミック層を0.7μm程度に薄層化しても、誘電特性や静電容量の温度特性を損なうことなく、低誘電損失でDCバイアス特性も良好な高比誘電率を有する信頼性の優れた積層セラミックコンデンサを得ることのできることが分った。   That is, according to Sample Nos. 18 to 83, even if the dielectric ceramic layer is thinned to about 0.7 μm, the dielectric characteristics and the temperature characteristics of the capacitance are not impaired, and the DC bias characteristics are good with a low dielectric loss. It was found that a highly reliable multilayer ceramic capacitor having a high dielectric constant can be obtained.
また、試料番号18〜21(主成分E〜H)と試料番号22〜83(主成分I〜S、及びD)の対比から明らかなように、Ca成分の含有モル量をTi成分100モル部に対し2モル部未満とすることにより、平均故障寿命は110〜120時間であるものの、DC変化率を絶対値で20%未満に抑制することができることが分った。さらに、Ca成分の含有モル量をTi成分100モル部に対し2〜15モル部とすることにより、DC変化率は絶対値で21.9〜24.9%となるものの、平均故障寿命は150〜190時間となり、より一層の長寿命化を図ることができることが分かった。   Further, as is clear from the comparison of sample numbers 18 to 21 (main components E to H) and sample numbers 22 to 83 (main components I to S and D), the molar content of the Ca component is 100 mol parts of the Ti component. However, it was found that by making the amount less than 2 mol parts, the average failure life was 110 to 120 hours, but the DC change rate could be suppressed to less than 20% in absolute value. Further, by setting the molar content of the Ca component to 2 to 15 mol parts with respect to 100 mol parts of the Ti component, the DC change rate becomes 21.9 to 24.9% in absolute value, but the average failure life is 150 It was found to be -190 hours, and it was possible to further extend the life.
X線スペクトルの半値幅ΔHを説明するための図である。It is a figure for demonstrating the half value width (DELTA) H of a X-ray spectrum. 本発明の誘電体セラミックを使用して製造された積層セラミックコンデンサの一実施の形態を示す断面図である。It is sectional drawing which shows one Embodiment of the laminated ceramic capacitor manufactured using the dielectric ceramic of this invention.
符号の説明Explanation of symbols
1 セラミック焼結体
2 内部電極
3 外部電極
1 Ceramic sintered body 2 Internal electrode 3 External electrode

Claims (5)

  1. (Ba,Ca)TiO(ただし、mは0.998〜1.020であり、Ca成分の含有モル量はTi成分100モル部に対し0〜15モル部である。)を主成分とし、副成分としてSiO、V、MnO、MgO、及びR(ただし、Rは、Y、La、CeO、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、及びLuの中から選択された少なくとも1種以上を示す。)を含有し、
    前記各副成分の含有モル量は、Ti成分100モル部に対し、SiOが0.5〜8.0モル部、Vが0.02〜1.0モル部、MnOが0.01〜5.0モル部、MgOが0.05〜3.0モル部、及びRが0.05〜2.5モル部であり、
    かつ、前記結晶粒界の成分分析を行った場合に、V成分の含有モル量を前記V成分の総含有モル量の2倍以上とする分析点が、結晶粒界中、全分析点の80%以上であり、
    前記V成分の含有モル量がTi成分100モル部に対し0.04モル部以上の結晶粒子の占める比率が、全結晶粒子中の5%以下(0%を含む。)であることを特徴とする誘電体セラミック。
    Main component is (Ba, Ca) m TiO 3 (where m is 0.998 to 1.020, and the molar content of Ca component is 0 to 15 mol parts per 100 mol parts of Ti component). , SiO 2 , V 2 O 5 , MnO, MgO, and R x O y as subcomponents (where R x O y is Y 2 O 3 , La 2 O 3 , CeO 2 , Nd 2 O 3 , Sm 2). In O 3 , Eu 2 O 3 , Gd 2 O 3 , Tb 2 O 3 , Dy 2 O 3 , Ho 2 O 3 , Er 2 O 3 , Tm 2 O 3 , Yb 2 O 3 , and Lu 2 O 3 At least one selected from the above)),
    The molar content of each subcomponent, with respect to Ti component 100 molar parts, SiO 2 is 0.5 to 8.0 molar parts, V 2 O 5 is from 0.02 to 1.0 molar parts, MnO 0. 01-5.0 mol parts, MgO 0.05-3.0 mol parts, and R x O y 0.05-2.5 mol parts,
    And when the component analysis of the said crystal grain boundary is performed, the analysis point which makes the content molar amount of V component more than twice the total content molar amount of the said V component is 80 of all the analysis points in a crystal grain boundary. % Or more,
    The ratio of the crystal grains having a molar content of the V component of 0.04 mol part or more to 100 mol parts of the Ti component is 5% or less (including 0%) in the total crystal particles. Dielectric ceramic.
  2. Ca成分の含有モル量が、Ti成分100モル部に対し2モル部未満であることを特徴とする請求項1記載の誘電体セラミック。   The dielectric ceramic according to claim 1, wherein the molar content of the Ca component is less than 2 mol parts per 100 mol parts of the Ti component.
  3. Ca成分の含有モル量が、Ti成分100モル部に対し2〜15モル部であることを特徴とする請求項1又は請求項2記載の誘電体セラミック。   3. The dielectric ceramic according to claim 1, wherein the molar content of the Ca component is 2 to 15 mol parts per 100 mol parts of the Ti component.
  4. (Ba,Ca)TiO(ただし、mは0.998〜1.020であり、Ca成分の含有モル量はTi成分100モル部に対し0〜15モル部である。)で表される主成分を作製する主成分作製工程と、
    SiOとVとを配合して得た配合物に熱処理を施して溶融させた後、急冷してSiO−V混晶物を得る混晶物作製工程と、
    前記主成分、前記SiO−V混晶物、MnO、MgO、及びR(Rは、Y、La、CeO、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、及びLuの中から選択された少なくとも1種以上を示す。)を配合して配合物を作製する配合物作製工程と、
    前記配合物に焼成処理を施してセラミック焼結体を作製する焼結体作製工程とを含むことを特徴とする誘電体セラミックの製造方法。
    (Ba, Ca) m TiO 3 (where m is 0.998 to 1.020, and the molar content of the Ca component is 0 to 15 parts by mole with respect to 100 parts by mole of the Ti component). A main component manufacturing process for manufacturing the main component;
    A mixed crystal production step of obtaining a SiO 2 —V 2 O 5 mixed crystal by rapidly heat-cooling the compound obtained by mixing SiO 2 and V 2 O 5 with heat treatment;
    The main component, the SiO 2 —V 2 O 5 mixed crystal, MnO, MgO, and R x O y (R x O y is Y 2 O 3 , La 2 O 3 , CeO 2 , Nd 2 O 3 , Sm 2 O 3 , Eu 2 O 3 , Gd 2 O 3 , Tb 2 O 3 , Dy 2 O 3 , Ho 2 O 3 , Er 2 O 3 , Tm 2 O 3 , Yb 2 O 3 , and Lu 2 O 3 A compound preparation step of preparing a compound by blending at least one selected from
    A method for producing a dielectric ceramic, comprising: a sintered body producing step of producing a ceramic sintered body by subjecting the blend to a firing treatment.
  5. 複数の誘電体層を積層したセラミック積層体が焼結されてなるセラミック焼結体と、該セラミック焼結体の内部に並列状に埋設された複数の内部電極と、前記セラミック焼結体の外表面に形成された外部電極とを備えた積層セラミックコンデンサにおいて、
    前記セラミック焼結体が、請求項1乃至請求項3のいずれかに記載の誘電体セラミックで形成されていることを特徴とする積層セラミックコンデンサ。
    A ceramic sintered body obtained by sintering a ceramic laminated body in which a plurality of dielectric layers are laminated, a plurality of internal electrodes embedded in parallel inside the ceramic sintered body, and an outer side of the ceramic sintered body In the multilayer ceramic capacitor provided with the external electrode formed on the surface,
    A multilayer ceramic capacitor, wherein the ceramic sintered body is formed of the dielectric ceramic according to any one of claims 1 to 3.
JP2006015386A 2006-01-24 2006-01-24 Dielectric ceramic and manufacturing method of dielectric ceramic, as well as laminated ceramic capacitor Pending JP2007197233A (en)

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