JP4487476B2 - Dielectric porcelain composition and electronic component - Google Patents

Description

【０１０９】
上記表中、絶縁抵抗（ＩＲ）の数値において、「ｍＥ＋ｎ」は「ｍ×１０^＋ｎ」を意味する。
【０１１０】
上記表に示される結果から、第１副成分中のＭｇと第２副成分中のＹとのモル比（Ｍｇ／Ｙ）が所定範囲内の場合に、応力干渉縞が観察される結晶粒子が観察視野の３０％以上となり、それらの本実施例のサンプルは、Ｘ８Ｒ特性を満足し、しかも、比誘電率および絶縁抵抗が十分に高く、かつ、誘電損失も問題ないことが判明した。なお、本実施例のサンプルは、Ｘ８Ｒ特性のほか、前記したＥＩＡＪ規格のＢ特性およびＥＩＡ規格のＸ７Ｒ特性も満足していた。
【０１１１】
また、第２副成分を含有することにより、十分なＩＲ寿命が得られることが確認できた。なお、この条件下では、寿命時間が１時間以上であれば、ＩＲ寿命が十分であるといえる。
【０１１２】
なお、別途サンプルを作製し、このサンプルについて走査型電子顕微鏡による組織の観察および密度測定を行った結果、第２副成分の含有量が１０モル以上になると、焼成温度１２８０℃の範囲では焼結性が不十分となることも確認された。焼結性が不十分であると、誘電損失、比誘電率、ＩＲ寿命などの特性が低くなってしまい、また、耐湿性や強度も不十分となる。なお、焼成温度をさらに高くすることによって焼結性を向上させることは可能であるが、１３２０℃を超えるような高温で焼成した場合、内部電極層の途切れや誘電体磁器組成物の還元が生じやすくなってしまう。
【０１１３】
実施例２
第２副成分として、Ｙｂ、Ｔｍ、Ｌｕ、Ｓｃ、Ｅｒを４．２６モル添加した以外は、実施例１の試料番号３と同様にして、本実施例の円板状サンプルを作製した（試料３−１，６〜９）。また、第２副成分として、何も添加しない、または本発明の範囲外のＹ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、ＤｙまたはＨｏを４．２６モル添加した以外は、実施例１の試料番号３と同様にして、比較例に係る円板状サンプルを作製した（試料１０〜２１）。これら円板状サンプルについて、実施例１と同様な測定を行った。結果を表２に示す。
【０１１４】
【表２】

【０１１５】
表２に示される結果から、第２副成分として何も添加しない、またはＹ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、ＤｙまたはＨｏを添加した比較例に係るサンプルと比較して、第２副成分としてＹｂ、Ｔｍ、Ｌｕ、ＳｃまたはＥｒを含有するサンプルでは、応力干渉縞が観察される結晶粒子が観察視野の３０％以上となり、それらの本実施例のサンプルは、実施例１と同様に、Ｘ８Ｒ特性を満足することが確認できた。
【０１１６】
実施例３
第５副成分としてのＹ_２ Ｏ_３ をさらに添加し、第２副成分を４．２６モル添加した以外は、実施例１の試料番号３と同様にしてサンプルを作製し（試料番号２２〜２４）、実施例１と同様な測定を行った。結果を表３に示す。参考までに、試料１も併せて示す。なお、焼成温度は１３２０℃とした。
【０１１７】
【表３】

【０１１８】
表３に示される結果から、Ｙｂ酸化物（第２副成分）に加えて、Ｙ酸化物（第５副成分）を添加することにより、ＩＲ寿命が向上することが確認できた。また、Ｙ酸化物添加による他の特性への悪影響も認められないことも確認できた。
【０１１９】
実施例４
第２副成分として、Ｓｃ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕを４モル添加した以外は、実施例１の試料番号３と同様にして、本実施例の円板状サンプルを作製した。また、第２副成分として、本発明の範囲外のＧｄ、Ｔｂ、Ｄｙ、ＹまたはＨｏを４モル添加した以外は、実施例１の試料番号３と同様にして、比較例に係る円板状サンプルを作製した。これら円板状サンプルについて、（００２）および（２００）結晶面のＸ線回折（ＸＲＤ）を測定した結果を図５に示す。これを見ると、第２副成分として、Ｅｒ、Ｓｃ、Ｔｍ、Ｙｂ、Ｌｕから選択される少なくとも１種を添加することによって、（２００）および（００２）結晶面のピーク位置が広がっていることが確認された。これは、ａ−ｃ軸比が大きくなっており、すなわちＢａＴｉＯ_３ の結晶軸が歪んでいることを示していると考えられる。換言すれば、ＢａＴｉＯ_３ 表面の一部にこれら（Ｅｒ、Ｓｃ、Ｔｍ、Ｙｂ、Ｌｕから選択される少なくとも１種）が固溶していくことによって、ＢａＴｉＯ_３ の結晶が歪んでくる。このため、ＢａＴｉＯ_３ の結晶内部に歪み、応力が発生し、ＴＥＭ観察時に干渉縞が認められると考えられる。
【０１２０】
本実施例の円板状サンプルを用いて、実施例１と同様にしてＸ８Ｒ特性を満足するかどうかを評価したところ、いずれもＸ８Ｒ特性を満足していた。
【０１２１】
なお、ＢａＴｉＯ_３ は強誘電体であるので、歪み応力によってキュリー温度や容量温度特性が変化すると考えられる。
【０１２２】
実施例５
第２副成分として、Ｓｃ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕを２モルまたは４．２６モル添加した以外は、実施例１の試料番号３（表１参照）と同様にして、本実施例のサンプルを作製した。また、第２副成分として、本発明の範囲外のＹを２モルまたは４．２６モル添加した以外は、実施例１の試料番号３と同様にして、比較例に係るサンプルを作製した。
【０１２３】
これらサンプルを、１５０℃で１時間熱処理し、無負荷状態で室温（２５℃）にて２４時間放置した後、ＬＣＲメーターにより測定電圧１ｋＨｚ，１Ｖｒｍｓで初期容量Ｃ_０ を測定した。次に、誘電体層１層あたり６．３Ｖの直流電界を４０℃にて１００時間印加した後、無負荷状態で室温（２５℃）にて放置した。放置開始から２４時間後および１１１時間後に、Ｃ_０ 測定の際と同じ条件で容量を測定し、初期容量Ｃ_ｏ からの変化量ΔＣ_１ を求めて、容量変化率ΔＣ_１ ／Ｃ_０ を算出した。
【０１２４】
その結果、Ｙを含有し、Ｘ７Ｒ特性を満足する比較例に係るサンプルに比較して、本実施例のサンプルは、直流電界下での容量の経時変化が比較例のサンプルと同等または小さくなり、信頼性が十分に高いことが確認できた。
【０１２５】
【発明の効果】
以上説明してきたように、本発明によれば、比誘電率が高く、容量温度特性がＥＩＡ規格のＸ８Ｒ特性（−５５〜１５０℃、ΔＣ＝±１５％以内）を満足し、還元性雰囲気中での焼成が可能であり、直流電界下での容量の経時変化が小さく、また絶縁抵抗の寿命を長くすることが可能な誘電体磁器組成物を提供することができる。
【０１２６】
この誘電体磁器組成物で構成された誘電体層を有する積層セラミックコンデンサなどの電子部品は、自動車の電子装置のように厳しい環境下で使用される各種機器内において安定した動作が可能であるため、適用される機器の信頼性を著しく向上させる。
【図面の簡単な説明】
【図１】 図１は本発明の一実施形態に係る積層セラミックコンデンサの断面図である。
【図２】 図２はコンデンサの容量温度特性を表すグラフである。
【図３】 図３（Ａ）は試料３のＴＥＭ写真、図３（Ｂ）は試料１のＴＥＭ写真である。
【図４】 図４は試料３と試料１の誘電体磁器組成物の温度−ＤＤＳＣ曲線を示すグラフである。
【図５】 図５はＢａＴｉＯ_３ ＋ＭｇＯ＋Ｒ_２ Ｏ_３ （Ｒ＝Ｇｄ、Ｔｂ、Ｄｙ、Ｙ、Ｈｏ、Ｅｒ、Ｓｃ、Ｔｍ、Ｙｂ、Ｌｕから選択される少なくとも１種）＋ＭｎＯ＋Ｖ_２ Ｏ_５ ＋（ＢａＣａ）ＳｉＯ_３ 系の（００２）および（２００）結晶面のＸ線回折（ＸＲＤ）チャートを示す図である。
【符号の説明】
１… 積層セラミックコンデンサ
１０… コンデンサ素子本体
２… 誘電体層
３… 内部電極層
４… 外部電極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dielectric ceramic composition having reduction resistance and an electronic component such as a multilayer ceramic capacitor using the dielectric ceramic composition.
[0002]
[Prior art]
Multilayer ceramic capacitors as electronic components are widely used as small-sized, large-capacity, high-reliability electronic components, and the number used in one electronic device is large. In recent years, with the miniaturization and high performance of devices, the demand for further miniaturization, larger capacity, lower cost, and higher reliability for multilayer ceramic capacitors has become increasingly severe.
[0003]
Multilayer ceramic capacitors are usually manufactured by laminating a paste for internal electrode layers and a paste for dielectric layers by a sheet method or a printing method, and simultaneously firing the internal electrode layers and the dielectric layers in the laminate. Is done.
[0004]
As the conductive material for the internal electrode layer, Pd or Pd alloy is generally used. However, since Pd is expensive, a relatively inexpensive base metal such as Ni or Ni alloy has been used. When a base metal is used as the conductive material for the internal electrode layer, the internal electrode layer is oxidized when fired in the atmosphere. Therefore, it is necessary to perform simultaneous firing of the dielectric layer and the internal electrode layer in a reducing atmosphere. is there. However, when firing in a reducing atmosphere, the dielectric layer is reduced and the specific resistance is lowered. For this reason, non-reducing dielectric materials have been developed.
[0005]
However, a multilayer ceramic capacitor using a non-reducing dielectric material has a problem that IR (insulation resistance) is significantly deteriorated by application of an electric field, that is, the IR life is short and the reliability is low.
[0006]
Further, when the dielectric is exposed to a DC electric field, there arises a problem that the relative dielectric constant εr decreases with time. In addition, a capacitor may be used by superimposing a DC voltage. Generally, when a DC voltage is applied to a capacitor having a dielectric composed mainly of a ferroelectric, there is a problem that the capacitance value is reduced (DC Bias characteristics). If the dielectric layer is made thin in order to reduce the size and capacity of the chip capacitor, the electric field applied to the dielectric layer when a DC voltage is applied becomes stronger. It becomes extremely large or the DC bias characteristics deteriorate.
[0007]
Furthermore, the capacitor is also required to have good temperature characteristics, and in particular, depending on the application, the temperature characteristics are required to be flat under severe conditions. In recent years, multilayer ceramic capacitors have been used in various electronic devices such as an engine electronic control unit (ECU), a crank angle sensor, and an antilock brake system (ABS) module mounted in an engine room of an automobile. Since these electronic devices are for performing engine control, drive control and brake control stably, it is required that the circuit has good temperature stability.
[0008]
The environment in which these electronic devices are used is expected to decrease to about −20 ° C. or lower in winter in cold regions, and to increase to about + 130 ° C. or higher in summer after engine startup. Recently, there is a tendency to reduce the number of wire harnesses that connect an electronic device and its control target equipment, and the electronic device is sometimes installed outside the vehicle, so the environment for the electronic device has become increasingly severe. Therefore, capacitors used in these electronic devices need to have flat temperature characteristics over a wide temperature range.
[0009]
As a capacitor material for temperature compensation having excellent temperature characteristics, (Sr, Ca) (Ti, Zr) O₃System, Ca (Ti, Zr) O₃System, Nd₂O₃-2TiO₂System, La₂O₃-2TiO₂Although systems etc. are generally known, these compositions have a very low dielectric constant (generally 100 or less), so it is practically impossible to produce a capacitor with a large capacity.
[0010]
As a dielectric ceramic composition having a high dielectric constant and flat capacity-temperature characteristics, BaTiO₃Is the main component, Nb₂O₅-Co₃O₄MgO-Y, rare earth elements (Dy, Ho, etc.), Bi₂O₃-TiO₂The composition which added etc. is known. The mechanism for flattening the capacity-temperature characteristics is not necessarily clarified, but in Japanese Patent Publication No. 7-118431, the capacity-temperature characteristics are flattened by dissolving Mg or a rare earth element in the core-shell structure. It is proposed to make it. However, the document “Key Engineering Materials Vols 17-24,157-158 (1999); A study on Capacitance Aging in Ni-Electroded, BaTiO₃ -Based MLCCs with X7R Characteristics, the core-shell structure may not be indispensable for the capacitance-temperature characteristics to satisfy the EIA standard X7R characteristics (-55 to 125 ° C, ΔC = within ± 15%). It has been reported.
[0011]
In addition, these BaTiO₃The temperature characteristics of the dielectric ceramic composition mainly composed of₃Therefore, it is very difficult to satisfy the R characteristic (within ΔC = ± 15%) of the capacity-temperature characteristic in a higher temperature range than that. For this reason, BaTiO₃The high dielectric constant material of the system could only satisfy the X7R characteristic (-55 to 125 ° C., ΔC = within ± 15%) of the EIA standard. Just satisfying the X7R characteristic cannot be applied to the automobile electronic device used in the severe environment described above. The electronic device requires a dielectric ceramic composition that satisfies the EIA standard X8R characteristics (−55 to 150 ° C., ΔC = ± 15% or less).
[0012]
BaTiO₃In order to satisfy the X8R characteristic in a dielectric ceramic composition containing as a main component, BaTiO₃It has been proposed to shift the Curie temperature to the high temperature side by replacing Ba in the interior with Bi, Pb or the like (Japanese Patent Laid-Open Nos. 10-25157 and 9-40465). BaTiO₃+ CaZrO₃+ ZnO + Nb₂O₅It has also been proposed to satisfy the X8R characteristic by selecting the composition of the system (Japanese Patent Laid-Open Nos. 4-29548, 4-292458, 4-292259, 5-109319, and 6). No. 243721).
[0013]
However, in any of these composition systems, Pb, Bi, and Zn, which are likely to be evaporated and scattered, are used, and firing in an oxidizing atmosphere such as in air is a prerequisite. For this reason, there is a problem that an inexpensive base metal such as Ni cannot be used for the internal electrode of the capacitor, and an expensive noble metal such as Pd, Au, or Ag must be used.
[0014]
[Problems to be solved by the invention]
The object of the present invention is that the dielectric constant is high, the capacitance-temperature characteristic satisfies the X8R characteristic (−55 to 150 ° C., ΔC = ± 15% or less) of the EIA standard, and firing in a reducing atmosphere is possible. An object is to provide a dielectric ceramic composition and an electronic component such as a multilayer ceramic capacitor using the same.
[0015]
[Means for Solving the Problems]
  In order to achieve the above object, a dielectric ceramic composition according to the first aspect of the present invention comprises:
  A main component comprising barium titanate;
  Mg, CaAnd from BaA first subcomponent comprising an oxide of at least one selected first element (M1);
  A second subcomponent comprising an oxide of at least one second element (R1) selected from Er, Sc, Tm, Yb and Lu;
  A third subcomponent comprising silicon oxide;
  V₂O₅, MoO₃And WO₃A fourth subcomponent comprising at least one selected from,
A sixth subcomponent comprising MnO;
A dielectric ceramic composition having at least
The ratio of each subcomponent to 100 moles of the main component is
1st subcomponent: 0.1-3 mol,
Second subcomponent: 0.5 to 7 mol (however, the number of moles of the second subcomponent is a ratio of R1 alone),
    Third subcomponent: 2 to 10 mol
4th subcomponent: 0.01-0.5 mol,
    Sixth subcomponent: 0.01 to 0.5 mol,
  The ratio (M1 / R1) of the number of moles of the first element of the first subcomponent to the number of moles of the second element of the second subcomponent is:0.1≦ (M1 / R1)≦ 1And
  When observed with a transmission electron microscope, crystal grains having interference fringes are contained at 30% or more of the observation field.
[0016]
  The dielectric ceramic composition according to the second aspect of the present invention is:
  A main component comprising barium titanate;
  Mg, CaAnd from BaA first subcomponent comprising an oxide of at least one selected first element (M1);
  A second subcomponent comprising an oxide of at least one second element (R1) selected from Er, Sc, Tm, Yb and Lu;
  A third subcomponent comprising silicon oxide;
  V₂O₅, MoO₃And WO₃4th subcomponent containing at least 1 sort (s) selected fromWhen,
A sixth subcomponent comprising MnO;
A dielectric ceramic composition having at least
  The ratio of each subcomponent to 100 moles of the main component is
    1st subcomponent: 0.1-3 mol,
    Second subcomponent: 0.5 to 7 mol (however, the number of moles of the second subcomponent is a ratio of R1 alone),
    Third subcomponent: 2 to 10 mol,
    4th subcomponent: 0.01-0.5 mol,
    Sixth subcomponent: 0.01 to 0.5 mol,
And
  The ratio (M1 / R1) of the number of moles of the first element of the first subcomponent to the number of moles of the second element of the second subcomponent is:0.1≦ (M1 / R1)≦ 1A dielectric ceramic composition.
[0018]
  Invention of the first aspectPreferably, the interference fringes are generated by stress.
[0021]
Preferably, the silicon oxide is (Ba, Ca)._xSiO_{2 + x}(Where x = 0.7 to 1.2). In this case, the ratio of Ba and Ca is arbitrary, and may contain only one of them.
[0022]
  Preferably, MnO is further included as the sixth subcomponent, and the content of the sixth subcomponent is 100 mol of the main component including barium titanate.0.01-0.5 molIt is.
[0023]
Preferably, as the barium titanate, the composition formula Ba_mTiO_{2 + m}M in the composition formula is 0.995 ≦ m ≦ 1.010, and the ratio of Ba and Ti is 0.995 ≦ Ba / Ti ≦ 1.010.
[0024]
Preferably, the fifth subcomponent further includes an oxide of R2 (wherein R2 is at least one selected from Y, Dy, Ho, Tb, Gd and Eu), and the content of the fifth subcomponent is , 9 mol or less, more preferably 0.5 to 9 mol (provided that the number of moles of the fifth subcomponent is a ratio of R2 alone) with respect to 100 mol of the main component containing barium titanate.
[0025]
Preferably, the total content of the second subcomponent and the fifth subcomponent is 13 mol or less, more preferably 10 mol or less with respect to 100 mol of the main component including barium titanate (however, the second subcomponent and the fifth subcomponent) The number of moles of subcomponents is the ratio of R1 and R2 alone).
[0026]
The electronic component according to the present invention is not particularly limited as long as it is an electronic component having a dielectric layer. For example, the electronic component is a multilayer ceramic capacitor element having a capacitor element body in which internal electrodes are alternately laminated together with dielectric layers. is there. In the present invention, the dielectric layer is composed of any one of the above dielectric ceramic compositions. The conductive material contained in the internal electrode layer is not particularly limited, but is Ni or Ni alloy, for example.
[0027]
[Action]
As a result of intensive studies to obtain a dielectric ceramic composition satisfying the X8R characteristics, the present inventors made up 30% or more of the observation field with crystal particles having interference fringes when observed with a transmission electron microscope. It has been found that a certain dielectric ceramic composition satisfies X8R characteristics.
[0028]
The dielectric ceramic composition according to the present invention has a high relative dielectric constant, a capacity-temperature characteristic that satisfies the X8R characteristic of the EIA standard, can be fired in a reducing atmosphere, and the capacity over time under a direct current electric field. Small change and long life of insulation resistance.
[0029]
Therefore, by using the dielectric ceramic composition of the present invention, it is easy to provide an electronic component such as a multilayer ceramic capacitor having excellent characteristics.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.
FIG. 2 is a graph showing the capacitance-temperature characteristics of the capacitor.
3A and 3B are TEM photographs of sample 3 and sample 1, respectively.
FIG. 4 is a graph showing temperature-DDSC curves of the dielectric ceramic compositions of Sample 3 and Sample 1.
FIG. 5 shows BaTiO₃+ MgO + R₂O₃(R = Gd, Tb, Dy, Y, Ho, Er, Sc, Tm, Yb, Lu selected from at least one) + MnO + V₂O₅+ (BaCa) SiO₃It is a figure which shows the X-ray-diffraction (XRD) chart of the (002) and (200) crystal plane of a system.
[0031]
Multilayer ceramic capacitor
As shown in FIG. 1, a multilayer ceramic capacitor 1 according to an embodiment of the present invention includes a capacitor element body 10 having a configuration in which dielectric layers 2 and internal electrode layers 3 are alternately stacked. At both ends of the capacitor element body 10, a pair of external electrodes 4 are formed which are electrically connected to the internal electrode layers 3 arranged alternately in the element body 10. The shape of the capacitor element body 10 is not particularly limited, but is usually a rectangular parallelepiped shape. Also, there is no particular limitation on the dimensions, and it may be an appropriate dimension according to the application. Usually, (0.6 to 5.6 mm) × (0.3 to 5.0 mm) × (0.3 ˜1.9 mm).
[0032]
The internal electrode layers 3 are laminated so that the end faces are alternately exposed on the surfaces of the two opposite ends of the capacitor element body 10. The pair of external electrodes 4 are formed at both ends of the capacitor element body 10 and are connected to the exposed end surfaces of the alternately arranged internal electrode layers 3 to constitute a capacitor circuit.
[0033]
Dielectric layer
The dielectric layer 2 contains the dielectric ceramic composition of the present invention.
The dielectric ceramic composition of the present invention comprises barium titanate (preferably, composition formula Ba_mTiO_{2 + m}And m is 0.995 ≦ m ≦ 1.010, and the ratio of Ba and Ti is 0.995 ≦ Ba / Ti ≦ 1.010). When observed with a microscope, the crystal particles having interference fringes are contained in an observation field of 30% or more, preferably 50% or more.
[0034]
If the content of the crystal particles having interference fringes is less than 30% of the field of view observed by a transmission electron microscope, the X8R characteristics cannot be satisfied.
[0035]
The reason why the interference fringes are observed is not necessarily clear, but it is considered that the interference fringes are caused by the reason that distortion and stress are generated because the additive partially reacts and diffuses.
[0036]
The average crystal grain size of the dielectric ceramic composition of the present invention is not particularly limited, and may be appropriately determined from a range of, for example, 0.1 to 3 μm according to the thickness of the dielectric layer. Capacitance-temperature characteristics tend to deteriorate as the dielectric layer is thinner, and worsen as the average crystal grain size is reduced. Therefore, the dielectric ceramic composition of the present invention is particularly effective when the average crystal grain size needs to be reduced, specifically when the average crystal grain size is 0.1 to 0.5 μm. is there. In addition, if the average crystal grain size is reduced, the IR lifetime becomes longer, and the change with time of the capacity under a direct current electric field is reduced. From this point, the average crystal grain size is preferably small as described above. .
[0037]
The Curie temperature (phase transition temperature from ferroelectric to paraelectric) of the dielectric ceramic composition of the present invention can be changed by selecting the composition, but is preferable for satisfying the X8R characteristics. Is 120 ° C. or higher, more preferably 123 ° C. or higher. The Curie temperature can be measured by DSC (differential scanning calorimetry) or the like.
[0038]
The thickness of the dielectric layer composed of the dielectric ceramic composition of the present invention is usually 40 μm or less, particularly 30 μm or less per layer. The lower limit of the thickness is usually about 2 μm. The dielectric ceramic composition of the present invention is effective in improving the capacity-temperature characteristics of a multilayer ceramic capacitor having such a thinned dielectric layer. The number of dielectric layers stacked is usually about 2 to 300.
[0039]
The multilayer ceramic capacitor using the dielectric ceramic composition of the present invention is suitable for use as an electronic device for equipment used in an environment of 80 ° C. or higher, particularly 125 to 150 ° C. In such a temperature range, the temperature characteristic of the capacitance satisfies the R characteristic of the EIA standard, and further satisfies the X8R characteristic. EIAJ standard B characteristics [capacity change rate within ± 10% at −25 to 85 ° C. (reference temperature 20 ° C.)] and EIA standard X7R characteristics (−55 to 125 ° C., ΔC = within ± 15%) at the same time It is possible to be satisfied.
[0040]
In a multilayer ceramic capacitor, an AC electric field of 0.02 V / μm or more, particularly 0.2 V / μm or more, more preferably 0.5 V / μm or more, and generally about 5 V / μm or less is superimposed on the dielectric layer. Then, a DC electric field of 5 V / μm or less is applied. Even when such an electric field is applied, the temperature characteristic of the capacitance is extremely stable.
[0041]
Moreover, in the dielectric ceramic composition of the present invention, an example of a composition under conditions under which interference fringes are observed when observed with a transmission electron microscope is shown below.
[0042]
  That is, such a composition contains barium titanate (preferably the composition formula Ba_mTiO_{2 + m}And m is 0.995 ≦ m ≦ 1.010, and the ratio of Ba and Ti is 0.995 ≦ Ba / Ti ≦ 1.010),
  Mg, CaAnd BaA first subcomponent comprising an oxide of at least one first element (M1) selected from:
  At least a second subcomponent including an oxide of at least one second element (R1) selected from Er, Sc, Tm, Yb and Lu, and the number of moles of the second element of the second subcomponent Of the number of moles of the first element of the first subcomponent with respect to(M1 / R1) is 0.1 ≦ (M1 / R1) ≦ 1.
[0043]
Preferably, the ratio of each subcomponent to 100 mol of the main component containing barium titanate is as follows: first subcomponent: 0.1-3 mol (preferably 0.5-2.5 mol), second subcomponent: 0 .5-7 mol (preferably 0.5-5 mol).
[0044]
The ratio of the second subcomponent is not the molar ratio of the R1 oxide, but the molar ratio of R1 alone. That is, for example, when an oxide of Yb is used as the second subcomponent, the ratio of the second subcomponent is 1 mol.₂O₃This means that the ratio of Yb is not 1 mol, but the ratio of Yb is 1 mol.
[0045]
In this specification, each oxide constituting the main component and each subcomponent is represented by a stoichiometric composition, but the oxidation state of each oxide may be out of the stoichiometric composition. However, the said ratio of each subcomponent is calculated | required by converting into the oxide of the said stoichiometric composition from the metal amount contained in the oxide which comprises each subcomponent.
[0046]
  The reasons for limiting the contents of the subcomponents are as follows.
  First subcomponent (Mg,Ca and BaIf the content of at least one first element (M1) oxide selected from (1) is too small, the capacity-temperature change rate becomes large. On the other hand, when there is too much content, sinterability will deteriorate. The composition ratio of each oxide in the first subcomponent is arbitrary.
[0047]
The second subcomponent (the oxide of at least one second element (R1) selected from Er, Sc, Tm, Yb, and Lu) has an effect of shifting the Curie temperature to the high temperature side, and has a flat capacitance-temperature characteristic. Effects. When there is too little content of a 2nd subcomponent, such an effect will become inadequate and a capacity | capacitance temperature characteristic will worsen. On the other hand, if the content is too large, the sinterability tends to deteriorate. Among the second subcomponents, Yb oxide is preferable because it has a high effect of improving characteristics and is inexpensive.
[0048]
By adjusting the ratio of the first subcomponent to the second subcomponent within the above range, a composition in which the interference fringes are observed can be obtained, the capacity-temperature characteristic (X8R characteristic) is flattened, and the CR product is obtained. And sinterability can also be improved.
[0049]
If necessary, the dielectric ceramic composition of the present invention contains 2 to 10 mol (more preferably 2 to 5 mol) of the third subcomponent containing silicon oxide with respect to 100 mol of the main component containing barium titanate. It is preferable that The third subcomponent is (Ba, Ca)._xSiO_{2 + x}(However, x = 0.7 to 1.2) is preferable. In this case, the ratio of Ba and Ca is arbitrary, and may contain only one of them. When the content of the third subcomponent (silicon oxide) is too small, the capacity-temperature characteristic is deteriorated, and IR (insulation resistance) tends to decrease. On the other hand, if the content is too large, the IR lifetime tends to be insufficient, and the dielectric constant tends to decrease rapidly. [(Ba, Ca) as a more preferred embodiment of the third subcomponent_xSiO_{2 + x}] Are contained in the first subcomponent, but are complex oxides (Ba, Ca)_xSiO_{2 + x}Since the melting point is low, the reactivity with respect to the main component is good, so in the present invention, it is preferable to add BaO and / or CaO as the composite oxide. (Ba, Ca) as a preferred embodiment of the third subcomponent_xSiO_{2 + x}X in is preferably 0.7 to 1.2, more preferably 0.8 to 1.1. If x is too small, that is, SiO₂If there is too much, the main component BaTiO₃Reacts and deteriorates dielectric properties. On the other hand, if x is too large, the melting point becomes high and the sinterability is deteriorated, which is not preferable. In addition, the ratio of Ba and Ca is arbitrary and may contain only one side.
[0050]
In the dielectric ceramic composition of the present invention, if necessary, V₂O₅, MoO₃And WO₃A fourth subcomponent containing at least one selected from the group consisting of 0.01 to 0.5 mol (more preferably 0.1 to 0.4 mol) per 100 mol of the main component containing barium titanate. Preferably it is. Fourth subcomponent (V₂O₅, MoO₃And WO₃) Shows the effect of flattening the capacity-temperature characteristics above the Curie temperature and the effect of improving the IR lifetime. If the content of the fourth subcomponent is too small, such an effect tends to be insufficient. On the other hand, when there is too much content, IR tends to fall remarkably. The constituent ratio of each oxide in the third subcomponent is arbitrary.
[0051]
In the dielectric ceramic composition of the present invention, 9 mol of R2 oxide (wherein R2 is at least one selected from Y, Dy, Ho, Tb, Gd and Eu) is included as a fifth subcomponent, if necessary. It is preferably contained in the following (more preferably 0.5 to 9 mol). This fifth subcomponent (R2 oxide) exhibits the effect of improving IR and IR lifetime, and has little adverse effect on the capacity-temperature characteristics. However, when there is too much content of R2 oxide, it exists in the tendency for sinterability to deteriorate. Among the fifth subcomponents, Y oxide is preferable because it has a high effect of improving characteristics and is inexpensive.
[0052]
The total content of the second subcomponent and the fifth subcomponent is preferably not more than 13 mol, more preferably not more than 10 mol (provided that the second subcomponent and the fifth subcomponent are included) with respect to 100 mol of the main component containing barium titanate. The number of moles of subcomponents is the ratio of R1 and R2 alone). This is for maintaining good sinterability.
[0053]
The dielectric ceramic composition of the present invention may contain MnO as the sixth subcomponent. The sixth subcomponent exhibits an effect of promoting sintering, an effect of increasing IR, and an effect of improving the IR life. In order to sufficiently obtain such an effect, the ratio of the sixth subcomponent to 100 mol of the main component containing barium titanate is preferably 0.01 mol or more. However, if the content of the sixth subcomponent is too large, the capacity-temperature characteristic is adversely affected.
[0054]
Further, in the dielectric ceramic composition of the present invention, in addition to the above oxides, Al₂O₃May be included. Al₂O₃Does not significantly affect the capacity-temperature characteristics and shows the effect of improving the sinterability, IR and IR lifetime. However, Al₂O₃When there is too much content of sinter, since sinterability will deteriorate and IR will become low, Al₂O₃Is preferably 1 mol or less, more preferably 1 mol or less of the entire dielectric ceramic composition, with respect to 100 mol of the main component containing barium titanate.
[0055]
In addition, when at least one of Sr, Zr, and Sn substitutes Ba or Ti in the main component constituting the perovskite structure, the Curie temperature shifts to the low temperature side, so the capacity-temperature characteristics at 125 ° C. or higher Becomes worse. For this reason, BaTiO containing these elements₃[For example, (Ba, Sr) TiO₃] Is preferably not used as the main component. However, there is no particular problem as long as the level is contained as an impurity (about 0.1 mol% or less of the entire dielectric ceramic composition).
[0056]
By satisfying such conditions, interference fringes appear, the capacity-temperature characteristic is improved, and the X8R characteristic can be satisfied.
[0057]
The dielectric ceramic composition containing a predetermined amount or more of crystal grains in which the interference fringes are observed can satisfy the above composition conditions, but the composition and manufacturing conditions are appropriately determined even if the dielectric ceramic composition has other physical properties. By controlling, the above characteristics (30% or more of crystal grains having interference fringes) can be satisfied.
[0058]
Internal electrode layer
The conductive material contained in the internal electrode layer 3 is not particularly limited, but a base metal can be used because the constituent material of the dielectric layer 2 has reduction resistance. As the base metal used as the conductive material, Ni or Ni alloy is preferable. The Ni alloy is preferably an alloy of Ni and one or more elements selected from Mn, Cr, Co and Al, and the Ni content in the alloy is preferably 95% by weight or more.
In addition, in Ni or Ni alloy, various trace components, such as P, may be contained about 0.1 wt% or less.
The thickness of the internal electrode layer may be appropriately determined according to the application, etc., but it is usually preferably about 0.5 to 5 μm, particularly preferably about 0.5 to 2.5 μm.
[0059]
External electrode
The conductive material contained in the external electrode 4 is not particularly limited, but in the present invention, inexpensive Ni, Cu, and alloys thereof can be used.
The thickness of the external electrode may be appropriately determined according to the use, etc., but is usually preferably about 10 to 50 μm.
[0060]
Manufacturing method of multilayer ceramic capacitor
In the multilayer ceramic capacitor using the dielectric ceramic composition of the present invention, as in the conventional multilayer ceramic capacitor, a green chip is produced by a normal printing method or sheet method using a paste, and this is fired, and then externally It is manufactured by printing or transferring an electrode and firing. Hereinafter, the manufacturing method will be specifically described.
[0061]
The dielectric layer paste may be an organic paint obtained by kneading a dielectric material and an organic vehicle, or may be a water-based paint.
[0062]
As the dielectric material, the above-mentioned oxide, a mixture thereof, and a composite oxide can be used. In addition, various compounds that become the above-described oxide or composite oxide by firing, for example, carbonate, oxalate, It can be appropriately selected from nitrates, hydroxides, organometallic compounds, etc., and used in combination. What is necessary is just to determine content of each compound in a dielectric material so that it may become a composition of an above-mentioned dielectric ceramic composition after baking.
[0063]
The dielectric material is usually used as a powder having an average particle size of about 0.1 to 3 μm.
[0064]
An organic vehicle is obtained by dissolving a binder in an organic solvent. The binder used for the organic vehicle is not particularly limited, and may be appropriately selected from usual various binders such as ethyl cellulose and polyvinyl butyral. Further, the organic solvent to be used is not particularly limited, and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, acetone, toluene, and the like, depending on a method to be used such as a printing method or a sheet method.
[0065]
Further, when the dielectric layer paste is used as a water-based paint, a water-based vehicle in which a water-soluble binder or a dispersant is dissolved in water and a dielectric material may be kneaded. The water-soluble binder used for the water-based vehicle is not particularly limited, and for example, polyvinyl alcohol, cellulose, water-soluble acrylic resin, or the like may be used.
[0066]
The internal electrode layer paste is obtained by kneading the above-mentioned organic vehicle with various conductive metals composed of various dielectric metals and alloys, or various oxides, organometallic compounds, resinates, etc. that become the above-mentioned conductive materials after firing. Prepare.
The external electrode paste may be prepared in the same manner as the internal electrode layer paste described above.
[0067]
There is no restriction | limiting in particular in content of the organic vehicle in each above-mentioned paste, For example, what is necessary is just about 1-5 weight% of binders, for example, about 10-50 weight% of binders. Each paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like as necessary. The total content of these is preferably 10% by weight or less.
[0068]
When the printing method is used, the dielectric layer paste and the internal electrode layer paste are laminated and printed on a substrate such as PET, cut into a predetermined shape, and then peeled from the substrate to obtain a green chip.
[0069]
When the sheet method is used, a dielectric layer paste is used to form a green sheet, the internal electrode layer paste is printed thereon, and these are stacked to form a green chip.
[0070]
Before firing, the green chip is subjected to binder removal processing. The binder removal process may be performed under normal conditions. However, when a base metal such as Ni or Ni alloy is used as the conductive material of the internal electrode layer, the heating rate is preferably 5 to 300 ° C./hour in an air atmosphere. More preferably, the temperature is 10 to 100 ° C./hour, the holding temperature is preferably 180 to 400 ° C., more preferably 200 to 300 ° C., and the temperature holding time is preferably 0.5 to 24 hours, more preferably 5 to 20 hours. To do.
[0071]
The atmosphere at the time of green chip firing may be appropriately determined according to the type of conductive material in the internal electrode layer paste, but when a base metal such as Ni or Ni alloy is used as the conductive material, the oxygen content in the firing atmosphere The pressure is 10^-8-10^-12It is preferable to set it to atmospheric pressure. When the oxygen partial pressure is less than the above range, the conductive material of the internal electrode layer may be abnormally sintered and may be interrupted. Further, when the oxygen partial pressure exceeds the above range, the internal electrode layer tends to be oxidized.
[0072]
Moreover, the holding temperature at the time of baking becomes like this. Preferably it is 1100-1400 degreeC, More preferably, it is 1200-1360 degreeC, More preferably, it is 1200-1320 degreeC. If the holding temperature is lower than the above range, the densification becomes insufficient. If the holding temperature is higher than the above range, the electrode temperature is interrupted due to abnormal sintering of the internal electrode layer, the capacity temperature characteristic deteriorates due to diffusion of the constituent material of the internal electrode layer, and the dielectric Reduction of the body porcelain composition is likely to occur.
[0073]
As other firing conditions, the rate of temperature rise is preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour, and the temperature holding time is preferably 0.5 to 8 hours, more preferably 1 to 3 hours. The time and cooling rate are preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour. The firing atmosphere is preferably a reducing atmosphere, and the atmosphere gas is, for example, N₂And H₂It is preferable to use a mixed gas with
[0074]
When firing in a reducing atmosphere, it is preferable to anneal the capacitor element body. Annealing is a process for re-oxidizing the dielectric layer, and this can significantly increase the IR lifetime, thereby improving the reliability.
[0075]
The oxygen partial pressure in the annealing atmosphere is 10^-6Above atmospheric pressure, especially 10^-5-10^-4It is preferable to set it to atmospheric pressure. When the oxygen partial pressure is less than the above range, it is difficult to reoxidize the dielectric layer, and when it exceeds the above range, the internal electrode layer tends to be oxidized.
[0076]
The holding temperature at the time of annealing is preferably 1100 ° C. or less, particularly 500 to 1100 ° C. When the holding temperature is lower than the above range, the dielectric layer is not sufficiently oxidized, so that the IR is low and the IR life tends to be short. On the other hand, if the holding temperature exceeds the above range, not only the internal electrode layer is oxidized and the capacity is lowered, but the internal electrode layer reacts with the dielectric substrate, the capacity temperature characteristic is deteriorated, the IR is lowered, the IR Life is likely to decrease. Note that annealing may be composed of only a temperature raising process and a temperature lowering process. That is, the temperature holding time may be zero. In this case, the holding temperature is synonymous with the maximum temperature.
[0077]
As other annealing conditions, the temperature holding time is preferably 0 to 20 hours, more preferably 6 to 10 hours, and the cooling rate is preferably 50 to 500 ° C./hour, more preferably 100 to 300 ° C./hour. . Further, as an atmosphere gas for annealing, for example, humidified N₂It is preferable to use gas or the like.
[0078]
In the above binder removal processing, firing and annealing, N₂In order to humidify gas or mixed gas, for example, a wetter or the like may be used. In this case, the water temperature is preferably about 5 to 75 ° C.
[0079]
The binder removal treatment, firing and annealing may be performed continuously or independently. When these are performed continuously, after removing the binder, the atmosphere is changed without cooling, and then the temperature is raised to the holding temperature at the time of baking to perform baking, and then cooled to reach the annealing holding temperature. Sometimes it is preferable to perform annealing by changing the atmosphere. On the other hand, when these are performed independently, during firing, up to the holding temperature during the binder removal process, N₂Gas or humidified N₂After raising the temperature in a gas atmosphere, it is preferable to further raise the temperature by changing the atmosphere. After cooling to the holding temperature during annealing, N₂Gas or humidified N₂It is preferable to change to a gas atmosphere and continue cooling. In annealing, N₂After raising the temperature to the holding temperature under a gas atmosphere, the atmosphere may be changed, and the entire annealing process is humidified N₂A gas atmosphere may be used.
[0080]
The capacitor element body obtained as described above is subjected to end surface polishing, for example, by barrel polishing or sand blasting, and the external electrode paste is printed or transferred and baked to form the external electrode 4. The firing condition of the external electrode paste is, for example, humidified N₂And H₂In the mixed gas, it is preferable to set the temperature at 600 to 800 ° C. for about 10 minutes to 1 hour. Then, if necessary, a coating layer is formed on the surface of the external electrode 4 by plating or the like.
The multilayer ceramic capacitor of the present invention thus manufactured is mounted on a printed circuit board by soldering or the like and used for various electronic devices.
[0081]
Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and can of course be implemented in various modes without departing from the gist of the present invention.
[0082]
For example, in the above-described embodiment, the multilayer ceramic capacitor is exemplified as the electronic component according to the present invention. However, the electronic component according to the present invention is not limited to the multilayer ceramic capacitor, and is composed of a dielectric ceramic composition having the above composition. Any material having a dielectric layer can be used.
[0083]
【Example】
Next, the present invention will be described in more detail with reference to examples that further embody the embodiment of the present invention. However, the present invention is not limited to only these examples.
[0084]
Example 1
A main component material and subcomponent materials each having a particle size of 0.1 to 1 μm were prepared. Carbonates were used as the raw materials for MgO and MnO, and oxides were used as the other raw materials. In addition, the raw material of the second subcomponent includes (Ba_0.6Ca_0.4) SiO₃Was used. (Ba_0.6Ca_0.4) SiO₃Is BaCO₃, CaCO₃And SiO₂Was mixed by wet mixing with a ball mill for 16 hours, dried, fired in air at 1150 ° C., and further wet-ground with a ball mill for 100 hours.
[0085]
The main component BaTiO₃Is BaCO₃And TiO₂Each of these was weighed, wet-mixed for about 16 hours using a ball mill, dried, and then fired in air at a temperature of 1100 ° C. for about 16 hours by wet pulverization. The same characteristics were obtained. In addition, the main component BaTiO₃The same characteristics were obtained even when using hydrothermal synthetic powders or those prepared by the oxalate method.
[0086]
These raw materials are composed of BaTiO whose composition is the main component after firing.₃It mix | blended so that it might become what is shown in following Table 1 with respect to 100 mol, Wet-mixed for 16 hours with the ball mill, It was made to dry and it was set as the dielectric material.
Next, 100 parts by weight of the obtained dielectric material after drying, 4.8 parts by weight of acrylic resin, 40 parts by weight of methylene chloride, 20 parts by weight of ethyl acetate, 6 parts by weight of mineral spirits, and 4 parts by weight of acetone Were mixed with a ball mill to form a paste, and a dielectric layer paste was obtained.
[0087]
Next, 100 parts by weight of Ni particles having an average particle size of 0.2 to 0.8 μm, 40 parts by weight of an organic vehicle (8 parts by weight of ethyl cellulose dissolved in 92 parts by weight of butyl carbitol), and 10 parts by weight of butyl carbitol Were kneaded with three rolls to obtain a paste, and an internal electrode layer paste was obtained.
[0088]
Next, 100 parts by weight of Cu particles having an average particle diameter of 0.5 μm, 35 parts by weight of an organic vehicle (8 parts by weight of ethyl cellulose resin dissolved in 92 parts by weight of butyl carbitol) and 7 parts by weight of butyl carbitol were kneaded. To obtain a paste for an external electrode.
[0089]
Next, a green sheet having a thickness of 15 μm was formed on the PET film using the dielectric layer paste, and the internal electrode layer paste was printed thereon, and then the green sheet was peeled from the PET film. Next, these green sheets and protective green sheets (not printed with internal electrode layer paste) were laminated and pressure-bonded to obtain green chips. The number of sheets having internal electrodes was four.
[0090]
Next, the green chip was cut into a predetermined size and subjected to binder removal processing, firing and annealing to obtain a multilayer ceramic fired body.
[0091]
The binder removal treatment was performed under conditions of a temperature rising time of 15 ° C./hour, a holding temperature of 280 ° C., a holding time of 8 hours, and an air atmosphere.
[0092]
Firing is performed at a heating rate of 200 ° C./hour, a holding temperature of 1280 ° C., a holding time of 2 hours, a cooling rate of 300 ° C./hour, and humidified N₂+ H₂Mixed gas atmosphere (oxygen partial pressure is 10^-9At atmospheric pressure).
[0093]
Annealing is performed at a holding temperature of 900 ° C., a temperature holding time of 9 hours, a cooling rate of 300 ° C./hour, and humidified N₂Gas atmosphere (oxygen partial pressure is 10^-5At atmospheric pressure). A wetter with a water temperature of 35 ° C. was used for humidifying the atmospheric gas during firing and annealing.
[0094]
Next, after polishing the end face of the multilayer ceramic fired body by sandblasting, the external electrode paste was transferred to the end face and humidified.₂+ H₂In an atmosphere, firing was performed at 800 ° C. for 10 minutes to form an external electrode, and a multilayer ceramic capacitor sample having the configuration shown in FIG. 1 was obtained.
[0095]
The size of each sample thus obtained is 3.2 mm × 1.6 mm × 0.6 mm, the number of dielectric layers sandwiched between internal electrode layers is 4, and the thickness is 10 μm. The thickness of the internal electrode layer was 1.5 μm.
[0096]
In addition to the capacitor sample, a disk-shaped sample was also produced. This disk-shaped sample has the same composition as the dielectric layer of each capacitor sample described above and the same firing conditions. In-Ga electrodes with a diameter of 5 mm are applied to both surfaces of the sample.
[0097]
The following characteristics were evaluated for each sample.
[0098]
Dielectric constant (εr), dielectric loss (tan δ)
The capacity and tan δ of the disc-shaped sample were measured at 25 ° C. using an LCR meter under the conditions of 1 kHz and 1 Vrms. Then, the relative dielectric constant was calculated from the capacitance, the electrode dimensions, and the thickness of the sample. The results are shown in each table.
[0099]
Insulation resistance (IR)
The specific resistance at 25 ° C. was measured for the disk-shaped sample. The specific resistance was measured with an insulation resistance meter (R8340A (50V-1 minute value) manufactured by Advantest Corporation). The results are shown in each table.
[0100]
Capacity temperature characteristics
The capacitance of the capacitor sample was measured in the temperature range of −55 to 160 ° C. to check whether the X8R characteristic was satisfied. Also, a sample containing Yb (Sample 3) was selected as an example of the present invention, a sample containing Y (Sample 1) was selected as a comparative example, and the capacity-temperature characteristics of these samples at −55 ° C. to 160 ° C. It is shown in FIG. FIG. 2 shows a rectangular range satisfying the X7R characteristic (inner rectangle in FIG. 2) and a rectangular range satisfying the X8R characteristic (outer rectangle in FIG. 2). For the measurement, an LCR meter (HP4284A) was used, and the measurement voltage was 1V.
[0101]
TEM ( Transmission Electron Microscope ) Observation of dielectric structure
In this example, the observation sample was prepared according to the following procedure. In particular, care was taken not to affect the observation sample.
[0102]
The capacitor sample was first polished to about 100 μm with a diamond saw and sandpaper. Next, the sample surface was buffed using a solution in which diamond powder of 1 μm or less was suspended. Subsequently, it grind | polished to the thickness of about 20 micrometers using the dipping grinder, and also grind | polished by ion milling, and produced the observation sample. During processing by ion milling, the sample stage was cooled using liquid nitrogen in order to prevent the temperature of the sample from rising.
[0103]
Next, the obtained observation sample is fixed to a sample holder of TEM (JEM-2000FXII manufactured by JEOL), and the structure of the set observation sample is observed under the conditions of an acceleration voltage of 200 kV and a magnification of 20000 to 50000, and interference. It was examined whether or not 30% or more of the observation visual field contained the fringed crystal particles. The results are shown in each table, with ○ being satisfied and × not being satisfied.
[0104]
Further, a TEM photograph of Sample 3 which is a typical composition of this example is shown in FIG. From this, it can be seen that 55%, which is 30% or more of the observation field (the entire area of the photograph), contains crystal grains having stress interference fringes. For comparison, a TEM photograph of Sample 1 is shown in FIG. 3B, but no crystal particles containing stress interference fringes were observed.
[0105]
The content value of the interference fringes was obtained by dividing (dividing) the total of the partial areas where the interference fringes were observed by the area of the entire observation field. The discrimination between the stress interference fringe and the interference fringe depending on the sample thickness was confirmed by changing the tilt angle. The domain was discriminated by confirming the disappearance of the domain by changing the tilt angle of the sample. Note that the inclination angle of the sample was changed by ± 5 degrees.
[0106]
IR lifetime under DC electric field
The capacitor sample was subjected to an acceleration test at 200 ° C. under an electric field of 10 V / μm, and the time until the insulation resistance became 1 MΩ or less was defined as the lifetime, and is shown in each table.
[0107]
Measurement by DSC
For the disk samples (Samples 1 and 3), the endothermic peak was measured by DSC (Differential Scanning Calorimetry) to determine the Curie temperature. In addition, the temperature-DDSC curve of a sample is shown in FIG. From this, it was confirmed that the sample of the example showed a shift of the Curie temperature to the high temperature side and an improvement of the temperature characteristics as compared with the sample of the comparative example.
[0108]
[Table 1]

[0109]
In the above table, in the value of insulation resistance (IR), “mE + n” is “m × 10”.^{+ N}"Means.
[0110]
From the results shown in the above table, when the molar ratio (Mg / Y) between Mg in the first subcomponent and Y in the second subcomponent is within a predetermined range, the crystal grains in which stress interference fringes are observed are It became 30% or more of the observation visual field, and those samples of this example satisfied the X8R characteristics, were sufficiently high in relative dielectric constant and insulation resistance, and were found to have no problem with dielectric loss. In addition to the X8R characteristic, the sample of this example satisfied the B characteristic of the EIAJ standard and the X7R characteristic of the EIA standard.
[0111]
Moreover, it has confirmed that sufficient IR lifetime was obtained by containing a 2nd subcomponent. Under this condition, if the lifetime is 1 hour or longer, it can be said that the IR lifetime is sufficient.
[0112]
In addition, when a sample was prepared separately and the structure was observed and the density was measured with a scanning electron microscope, the content of the second subcomponent was 10 mol or more, and sintering was performed at a firing temperature of 1280 ° C. It was also confirmed that the property was insufficient. If the sinterability is insufficient, characteristics such as dielectric loss, relative dielectric constant, IR life and the like are lowered, and moisture resistance and strength are also insufficient. Although it is possible to improve the sinterability by further increasing the firing temperature, when firing at a high temperature exceeding 1320 ° C., the internal electrode layer is interrupted and the dielectric ceramic composition is reduced. It becomes easy.
[0113]
Example 2
A disk-shaped sample of this example was prepared in the same manner as the sample number 3 of Example 1 except that 4.26 mol of Yb, Tm, Lu, Sc, Er was added as the second subcomponent (sample) 3-1, 6-9). Further, nothing is added as the second subcomponent, or 4.26 mol of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy or Ho outside the scope of the present invention is added. In the same manner as Sample No. 3 in Example 1, disc-shaped samples according to Comparative Examples were produced (Samples 10 to 21). About these disk-shaped samples, the same measurement as Example 1 was performed. The results are shown in Table 2.
[0114]
[Table 2]

[0115]
From the results shown in Table 2, comparison is made with the sample according to the comparative example in which nothing is added as the second subcomponent or Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy or Ho is added. Then, in the sample containing Yb, Tm, Lu, Sc or Er as the second subcomponent, the crystal particles in which the stress interference fringes are observed are 30% or more of the observation field. As in Example 1, it was confirmed that the X8R characteristics were satisfied.
[0116]
Example 3
Y as the fifth subcomponent₂O₃Was added in the same manner as in Sample No. 3 of Example 1 except that 4.26 mol of the second subcomponent was added (Sample Nos. 22 to 24), and the same measurement as in Example 1 was performed. went. The results are shown in Table 3. For reference, Sample 1 is also shown. The firing temperature was 1320 ° C.
[0117]
[Table 3]

[0118]
From the results shown in Table 3, it was confirmed that the IR lifetime was improved by adding Y oxide (fifth subcomponent) in addition to Yb oxide (second subcomponent). It was also confirmed that no adverse effects on other characteristics due to the addition of Y oxide were observed.
[0119]
Example 4
A disk-shaped sample of this example was produced in the same manner as the sample number 3 of Example 1 except that 4 mol of Sc, Er, Tm, Yb, and Lu were added as the second subcomponent. Further, as a second subcomponent, a disk shape according to a comparative example was obtained in the same manner as in sample number 3 of Example 1 except that 4 mol of Gd, Tb, Dy, Y or Ho outside the scope of the present invention was added. A sample was made. FIG. 5 shows the results of measuring X-ray diffraction (XRD) of the (002) and (200) crystal planes for these disc samples. Looking at this, the peak position of the (200) and (002) crystal planes is expanded by adding at least one selected from Er, Sc, Tm, Yb, and Lu as the second subcomponent. Was confirmed. This is because the ac ratio is large, that is, BaTiO.₃This is considered to indicate that the crystal axis is distorted. In other words, BaTiO₃When these (at least one selected from Er, Sc, Tm, Yb, and Lu) are dissolved in part of the surface, BaTiO 3 is dissolved.₃The crystals are distorted. For this reason, BaTiO₃It is considered that distortion and stress are generated inside the crystal and interference fringes are observed during TEM observation.
[0120]
Using the disk-shaped sample of this example, whether or not the X8R characteristic was satisfied was evaluated in the same manner as in Example 1, all of them satisfied the X8R characteristic.
[0121]
BaTiO₃Is a ferroelectric, it is considered that the Curie temperature and the capacitance-temperature characteristic change due to the strain stress.
[0122]
Example 5
The sample of this example was the same as Sample No. 3 of Example 1 (see Table 1) except that 2 mol or 4.26 mol of Sc, Er, Tm, Yb, Lu was added as the second subcomponent. Was made. Further, a sample according to a comparative example was produced in the same manner as the sample number 3 of Example 1 except that 2 mol or 4.26 mol of Y outside the range of the present invention was added as the second subcomponent.
[0123]
These samples were heat-treated at 150 ° C. for 1 hour, allowed to stand at room temperature (25 ° C.) for 24 hours in an unloaded state, and then measured with an LCR meter at an initial capacity C at a measurement voltage of 1 kHz and 1 Vrms.₀Was measured. Next, a DC electric field of 6.3 V per dielectric layer was applied at 40 ° C. for 100 hours, and then allowed to stand at room temperature (25 ° C.) in an unloaded state. After 24 hours and 111 hours from the start of standing, C₀The capacity is measured under the same conditions as the measurement, and the initial capacity C_oChange from ΔC₁For the capacity change rate ΔC₁/ C₀Was calculated.
[0124]
As a result, compared to the sample according to the comparative example containing Y and satisfying the X7R characteristic, the sample of this example has the same or smaller change in capacity over time under a DC electric field, It was confirmed that the reliability was sufficiently high.
[0125]
【The invention's effect】
As described above, according to the present invention, the dielectric constant is high, the capacitance-temperature characteristic satisfies the X8R characteristic (−55 to 150 ° C., ΔC = ± 15% or less) of the EIA standard, and in a reducing atmosphere. It is possible to provide a dielectric porcelain composition that can be fired at a low temperature, has a small change with time in the capacity under a direct current electric field, and can extend the life of the insulation resistance.
[0126]
An electronic component such as a multilayer ceramic capacitor having a dielectric layer composed of this dielectric ceramic composition can operate stably in various devices used in harsh environments such as an electronic device of an automobile. , Significantly improve the reliability of the equipment applied.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.
FIG. 2 is a graph showing capacitance temperature characteristics of a capacitor.
3A is a TEM photograph of sample 3, and FIG. 3B is a TEM photograph of sample 1. FIG.
FIG. 4 is a graph showing temperature-DDSC curves of the dielectric ceramic compositions of Sample 3 and Sample 1.
FIG. 5 shows BaTiO₃+ MgO + R₂O₃(R = Gd, Tb, Dy, Y, Ho, Er, Sc, Tm, Yb, Lu selected from at least one) + MnO + V₂O₅+ (BaCa) SiO₃It is a figure which shows the X-ray-diffraction (XRD) chart of the (002) and (200) crystal plane of a system.
[Explanation of symbols]
1 ... Multilayer ceramic capacitor
10 ... Capacitor element body
2 ... Dielectric layer
3 ... Internal electrode layer
4 ... External electrode

Claims (5)

A main component comprising barium titanate;
A first subcomponent comprising an oxide of at least one first element (M1) selected from Mg, Ca and Ba ;
A second subcomponent comprising an oxide of at least one second element (R1) selected from Er, Sc, Tm, Yb and Lu;
A third subcomponent comprising silicon oxide;
A fourth subcomponent comprising at least one selected from V ₂ O ₅ , MoO ₃ and WO ₃ ;
A sixth subcomponent comprising MnO;
A dielectric ceramic composition having at least
The ratio of each subcomponent to 100 moles of the main component is
1st subcomponent: 0.1-3 mol,
Second subcomponent: 0.5 to 7 mol (however, the number of moles of the second subcomponent is a ratio of R1 alone),
Third subcomponent: 2 to 10 mol
4th subcomponent: 0.01-0.5 mol,
Sixth subcomponent: 0.01 to 0.5 mol,
The ratio (M1 / R1) of the number of moles of the first element of the first subcomponent to the number of moles of the second element of the second subcomponent is 0.1 ≦ (M1 / R1) ≦ 1 ,
A dielectric ceramic composition containing 30% or more of crystal grains having interference fringes when observed with a transmission electron microscope. A main component comprising barium titanate;
A first subcomponent comprising an oxide of at least one first element (M1) selected from Mg, Ca and Ba ;
A second subcomponent comprising an oxide of at least one second element (R1) selected from Er, Sc, Tm, Yb and Lu;
A third subcomponent comprising silicon oxide;
A fourth subcomponent comprising at least one selected from V ₂ O ₅ , MoO ₃ and WO ₃ ;
A sixth subcomponent comprising MnO;
A dielectric ceramic composition having at least
The ratio of each subcomponent to 100 moles of the main component is
1st subcomponent: 0.1-3 mol,
Second subcomponent: 0.5 to 7 mol (however, the number of moles of the second subcomponent is a ratio of R1 alone),
Third subcomponent: 2 to 10 mol,
4th subcomponent: 0.01-0.5 mol,
Sixth subcomponent: 0.01 to 0.5 mol,
And
The dielectric ceramic composition in which the ratio (M1 / R1) of the number of moles of the first element of the first subcomponent to the number of moles of the second element of the second subcomponent is 0.1 ≦ (M1 / R1) ≦ 1 object. The silicon _{oxide, (Ba, Ca) x SiO} 2 + x ( however, x = 0.7 to 1.2) the dielectric ceramic composition according to claim 1 or 2 is. The barium titanate is represented by the composition formula Ba _m TiO _{2 + m} , _m in the composition formula is 0.995 ≦ m ≦ 1.010, and the ratio of Ba to Ti is 0.995 ≦ Ba / Ti ≦ The dielectric ceramic composition according to any one of claims 1 to 3 , wherein the dielectric ceramic composition is 1.010. An electronic component having a dielectric layer,
Electronic components the dielectric layer, characterized in that are constituted by any of dielectric ceramic composition of claims 1-4.

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