JP4576807B2 - Dielectric porcelain composition and electronic component - Google Patents

Description

【０１２４】
評価１
表１に示すように、Ｒ１（第４副成分）とＲ２（第５副成分）とが含まれている本実施例の試料を用いた試料１〜４は、Ｂ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、誘電損失が低く、ＣＲ積が良好で、ＤＣバイアス特性、高温負荷寿命も良好であることが判明した。また、本実施例の試料は、ＥＩＡ規格のＢ特性も満足することが確認された。
【０１２５】
これに対し、表１に示すように、Ｒ１（第４副成分）のみが含まれている比較例の試料では、Ｂ特性は満足するが、誘電率、ＤＣバイアス特性、高温負荷寿命（ＨＡＬＴ）が悪化することが確認された。
【０１２６】
なお、Ｒ２としてＳｃなどの希土類が含まれている試料では、高温負荷寿命または誘電損失が悪化することが、特願２００３−６６４９号に示す実験により明らかとなっている。また、Ｒ２（第５副成分）のみが含まれている比較例の試料では、静電容量の温度特性が悪くなることが、特願２００３−６６４９号に示す実験により明らかとなっている。
【０１２７】
実施例２
下記表２に示すように、平均粒径０．２μｍの主成分原料（母材）を用い、１層あたりの誘電体層の厚み（層間厚み）を約３．５μｍとした以外は、実施例１と同様にして、コンデンサの試料１１〜１４を作製し、同様な測定を行った。結果を表２に示す。
【０１２８】
比較例２
第５副成分におけるＲ２の酸化物のモル数を、０モル％とした以外は、実施例２と同様にして、コンデンサの試料１５を作製し、同様な測定を行った。結果を表２に示す。
【０１２９】
【表２】

【０１３０】
評価２
表１に比べて、表２に示すように、母材の粒径を小さくし、誘電体層の厚みを、さらに薄くした場合には、εが低下することが確認された。しかしながら、表２に示す実施例２では、表１に示す実施例１に比べて、ＣＲ積が向上することが確認された。
【０１３１】
実施例３
下記表３に示すように、第４副成分におけるＲ１の種類を、Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ，Ｌｕに代え、第５副成分におけるＲ２の種類をＴｂに固定した以外は、実施例１と同様にして、コンデンサの試料２１〜２５を作製し、同様な測定を行った。結果を表３に示す。
【０１３２】
【表３】

【０１３３】
評価３
表３に示すように、Ｒ１（第４副成分）として、Ｙの代わりに、Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ，Ｌｕを用いた場合にも、実施例１と同様な傾向があることが確認できた。なお、表１と表３とを比較することで、Ｒ１としては、Ｙを用いることが、ε、ｔａｎδ、ＣＲ積の観点から好ましいことが確認できた。
【０１３４】
実施例４
実施例２におけるＲ１＝Ｙ，Ｒ２＝Ｅｕ，Ｇｄ，Ｔｂの組合せにおいて、Ｒ１のモル数を４．０モルとし、Ｒ２のモル数を０〜２．１モルの範囲で変化させた以外は、実施例１と同様にして、コンデンサの試料を作製し、実施例１と同様にして、ε、ＤＣバイアス特性、ＨＡＬＴの測定を行った。結果を、図３〜図５に示す。
【０１３５】
これらの図３〜図５に示すように、ε、ＤＣバイアス特性、ＨＡＬＴは、Ｒ２が０モル超２モル以下、好ましくは０．１〜１．５モルの時に、特に向上することが確認できた。
【０１３６】
実施例５
実施例２におけるＲ１＝Ｙ，Ｒ２＝Ｅｕ，Ｇｄ，Ｔｂの組合せにおいて、Ｒ１のモル数を４．０モルとし、Ｒ２のモル数を０〜２．５モルの範囲で変化させた以外は、実施例１と同様にして、コンデンサの試料を作製し、実施例１と同様にして、ε、ＤＣバイアス特性、ＨＡＬＴの測定を行った。Ｒ２（Ｅｕ，Ｙ，Ｔｂ）のモル数Ｍ２に対するＲ１（Ｙ）のモル数Ｍ１の比（Ｍ１／Ｍ２）を横軸にして、ε、ＤＣバイアス特性、ＨＡＬＴの測定結果を縦軸にしてグラフ化した図６〜８に示す。
【０１３７】
これらの図６〜図８に示すように、ε、ＤＣバイアス特性、ＨＡＬＴは、Ｍ１／Ｍ２が４＜Ｍ１／Ｍ２≦１００、さらに好ましくは４＜Ｍ１／Ｍ２≦８０の時に、特に向上することが確認できた。
【０１３８】
【発明の効果】
以上説明してきたように、本発明によれば、誘電体層を薄層化（または母材の微粉化）したとしても、誘電率を向上させ、直流電圧印加時の静電容量の変化が少なく（直流バイアス特性が良好）、絶縁抵抗の加速寿命が向上し、信頼性をさらに向上させることができる誘電体磁器組成物を提供することができる。
【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（Ａ）は誘電体粒子の模式図、図２（Ｂ）は誘電体粒子における希土類元素の濃度分布を示すグラフである。
【図３】図３（Ａ）〜図３（Ｃ）は本発明の実施例に係る誘電体磁器組成物における第５副成分と比誘電率との関係を示すグラフである。
【図４】図４（Ａ）〜図４（Ｃ）は本発明の実施例に係る誘電体磁器組成物における第５副成分と直流バイアス特性との関係を示すグラフである。
【図５】図５（Ａ）〜図５（Ｃ）は本発明の実施例に係る誘電体磁器組成物における第５副成分と絶縁抵抗の加速寿命との関係を示すグラフである。
【図６】図６（Ａ）〜図６（Ｃ）は本発明の他の実施例に係る誘電体磁器組成物における第５副成分に対する第４副成分のモル比と比誘電率との関係を示すグラフである。
【図７】図７（Ａ）〜図７（Ｃ）は本発明の他の実施例に係る誘電体磁器組成物における第５副成分に対する第４副成分のモル比と直流バイアス特性との関係を示すグラフである。
【図８】図８（Ａ）〜図８（Ｃ）は本発明の実施例に係る誘電体磁器組成物における第５副成分に対する第４副成分のモル比と絶縁抵抗の加速寿命との関係を示すグラフである。
【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
２２… 誘電体粒子
２２２… 強誘電体部分
２２４… 拡散部分
２４… 粒界偏析部分
２５… 粒界
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 used as, for example, a dielectric layer of a multilayer ceramic capacitor, and an electronic component using the dielectric ceramic composition as a dielectric layer.
[0002]
[Prior art]
A multilayer ceramic capacitor, which is an example of an electronic component, includes, for example, ceramic green sheets made of a predetermined dielectric ceramic composition and internal electrode layers of a predetermined pattern alternately stacked, and then integrated into a green chip obtained simultaneously. Manufactured by firing. Since the internal electrode layer of the multilayer ceramic capacitor is integrated with the ceramic dielectric by firing, it is necessary to select a material that does not react with the ceramic dielectric. For this reason, as a material constituting the internal electrode layer, conventionally, an expensive noble metal such as platinum or palladium has been inevitably used.
[0003]
However, in recent years, dielectric ceramic compositions that can use inexpensive base metals such as nickel and copper have been developed, and a significant cost reduction has been realized.
[0004]
In recent years, there has been a high demand for downsizing of electronic components accompanying the increase in the density of electronic circuits, and the downsizing and increase in capacity of multilayer ceramic capacitors are rapidly progressing. Accordingly, the dielectric layer per layer in the multilayer ceramic capacitor has been thinned, and a dielectric ceramic composition that can maintain the reliability as a capacitor even when the layer is thinned is demanded. Particularly for miniaturization and large capacity, very high reliability is required for the dielectric ceramic composition. This is because when the dielectric layer is made thinner for miniaturization and larger capacity, the electric field applied to each dielectric layer becomes stronger when a DC voltage is applied. That is, the change in capacity with time and the deterioration of the insulation resistance in the high humidity load test are remarkably increased.
[0005]
Conventionally, a base metal can be used as a material constituting the internal electrode, and the technology in which the temperature change of the capacitance satisfies the EIA standard X7R characteristic (−55 to 125 ° C., ΔC = ± 15% or less) The applicant has proposed a dielectric ceramic composition disclosed in Patent Documents 1 and 2 below. These technologies are all Y₂O₃To improve the accelerated life of insulation resistance (IR). However, as miniaturization and capacity increase rapidly, further improvement in reliability is required.
[0006]
On the other hand, as another technique that satisfies the X7R characteristic, for example, a dielectric ceramic composition disclosed in Patent Document 3 is also known.
[0007]
In such a dielectric ceramic composition, an oxide of at least one rare earth element of Sc and Y and an oxide of at least one rare earth element of Gd, Tb, and Dy are added to barium titanate. Is. That is, the technique disclosed in Patent Document 3 adds X7R of EIA standard by adding at least two kinds of rare earth element oxides each selected from two arbitrarily divided element groups to barium titanate. It is intended to satisfy the characteristics and improve the accelerated life of the insulation resistance.
[0008]
However, in the technique disclosed in Patent Document 3, if the X7R characteristic is to be satisfied, the accelerated life of the insulation resistance after firing is shortened, and there is a problem regarding the balance between the X7R characteristic and the life. . Moreover, as the size and capacity are further increased, the dielectric loss (tan δ) increases and the reliability of the DC bias and the like tends to deteriorate, and these improvements have been demanded.
[0009]
In Patent Document 3, two types of rare earth oxides are added, but the ratio of the number of moles of these two types of rare earth elements is 4 or less, and the dielectric layer is made thinner. Had problems in terms. That is, in order to reduce the thickness of the dielectric layer, it is necessary to reduce the particle size of the dielectric powder, which is a base material for forming the dielectric layer. There were problems such as a decrease in bias characteristics and lifetime.
[0010]
Incidentally, Patent Document 4 discloses a dielectric material having good temperature characteristics for the purpose of satisfying the range of the X8R characteristics of the EIA standard. This is because rare earth elements are added for the purpose of maintaining good temperature characteristics. Therefore, the types of rare earth elements to be added are different, and attention is paid to the ion radius of the rare earth elements. is not.
[0011]
In view of such circumstances, the present applicant has previously filed an application shown in Patent Document 5 below. According to the application shown in Patent Document 5, a medium-voltage capacitor that satisfies the X7R characteristics and has excellent characteristics can be obtained. As a result of further research on the composition shown in Patent Document 5, the present inventors have completed the following present invention.
[0012]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-84692
[Patent Document 2]
JP-A-6-342735
[Patent Document 3]
JP-A-10-223471
[Patent Document 4]
JP 2000-154057 A
[Patent Document 5]
Japanese Patent Application No. 2003-6649.
[0013]
[Problems to be solved by the invention]
An object of the present invention is to improve the dielectric constant particularly in a dielectric ceramic composition having excellent resistance to temperature during firing and having excellent capacity-temperature characteristics after firing, and the capacitance changes when a DC voltage is applied. It is an object of the present invention to provide a dielectric ceramic composition that has a small amount (good DC bias characteristics), an improved accelerated life of insulation resistance, and can further improve reliability. Another object of the present invention is to provide an electronic component such as a multilayer ceramic capacitor manufactured using such a dielectric ceramic composition and having improved reliability. In particular, an object of the present invention is to provide an electronic component such as a multilayer ceramic capacitor that can be made thinner and smaller.
[0014]
[Means for solving the problems and effects]
In the previous application shown in Patent Document 5, research on the effect of addition of rare earth elements to barium titanate is advanced, and adding a plurality of rare earth elements to barium titanate is effective in improving the high temperature load life. The knowledge that there is. And the knowledge that the distribution of the additive elements added together with the rare earth element changes depending on the ionic radius of the rare earth element, which changes the electrical characteristics expressed in the multilayer ceramic capacitor. Obtained. After that, as a result of further research on the premise of these, as the ionic radius of the rare earth element added increases, the solid solubility in the barium titanate particles increases, and the rare earth element deepens inside the barium titanate particles. Distributed to the part. And segregation of rare earth elements and additive elements, particularly alkaline earth elements, is reduced. As a result, it was confirmed that although the insulation resistance is increased and the reliability such as the high temperature load life is improved, the relative permittivity is decreased, the temperature change of the capacitance is increased, and the X7R characteristic is not satisfied. On the other hand, when the ion radius of the rare earth element added is small, the temperature change of the capacitance is small, but rare earth elements and alkaline earth elements are easily segregated together with Si added as a sintering aid. It was confirmed that the reliability as a capacitor was lowered.
[0015]
Therefore, in the previous application, focusing on the ionic radius of rare earth elements to barium titanate, research on adding a plurality of rare earth elements with different ionic radii was advanced, and the following dielectric ceramic composition was developed.
[0016]
That is,
A main component comprising barium titanate;
A fourth subcomponent including an oxide of R1 (wherein R1 is at least one selected from a first element group composed of rare earth elements having an effective ionic radius of 9 coordination of less than 108 pm);
And a second subcomponent including an oxide of R2 (wherein R2 is at least one selected from a second element group composed of rare earth elements having an effective ion radius of 108 pm to 113 pm at the time of 9 coordination) A dielectric ceramic composition was developed.
[0017]
According to the preceding invention, the reduction resistance during firing is excellent, and after firing, the dielectric constant, dielectric loss, insulation resistance, bias characteristics, breakdown voltage, capacity-temperature characteristics (for example, X7R characteristics or B characteristics) are excellent. It is possible to provide a dielectric porcelain composition having excellent characteristics and an accelerated accelerated life of insulation resistance.
[0018]
As a result of further research on the composition of the previous invention, the inventors have determined that the number of moles of the fourth subcomponent and the number of moles of the fifth subcomponent are within a specific range with respect to the main component. In addition, by making the ratio of these mole numbers within a specific range, even when the dielectric layer is thin (when the particle size of the base material is reduced), the dielectric constant is improved and the DC voltage is applied. It has been found that the change in capacitance is small (the DC bias characteristic is good), the accelerated life of the insulation resistance is improved, and the reliability can be further improved, and the present invention has been completed.
[0019]
That is, the dielectric ceramic composition according to the first aspect of the present invention is:
A main component comprising barium titanate;
A fourth subcomponent including an oxide of R1 (wherein R1 is at least one selected from a first element group composed of rare earth elements having an effective ionic radius of 9 coordination of less than 108 pm);
A fifth subcomponent containing an oxide of R2 (wherein R2 is at least one selected from a second element group consisting of rare earth elements having an effective ionic radius of 108 pm to 113 pm at the time of nine coordination), And
The ratio of each subcomponent to 100 moles of the main component is the fourth subcomponent: more than 0 moles and 10 moles or less (however, the number of moles of the fourth subcomponent is the ratio of R1 alone), the fifth subcomponent: 0 moles 2 mol or less (however, the number of moles of the fifth subcomponent is the ratio of R2 alone),
The ratio (M1 / M2) of the number of moles M1 of R1 to the number of moles M2 of R2 is 4 <M1 / M2 ≦ 100.
[0020]
The dielectric ceramic composition according to the second aspect of the present invention is:
A main component comprising barium titanate;
A fourth oxide containing an oxide of R1 (wherein R1 is at least one selected from a first element group consisting of rare earth elements having an effective ionic radius of less than 108 pm in 9-coordination and includes at least Y); Subcomponents,
A fifth subcomponent containing an oxide of R2 (wherein R2 is at least one selected from a second element group consisting of rare earth elements having an effective ionic radius of 108 pm to 113 pm at the time of nine coordination), And
The ratio of each subcomponent to 100 moles of the main component is the fourth subcomponent: more than 0 moles and 10 moles or less (however, the number of moles of the fourth subcomponent is the ratio of R1 alone), the fifth subcomponent: 0 moles 2 mol or less (however, the number of moles of the fifth subcomponent is the ratio of R2 alone),
The ratio (M1 / M2) of the number of moles M1 of R1 to the number of moles M2 of R2 is 4 <M1 / M2 ≦ 100.
[0021]
Preferably, R1 is at least one of Y, Ho, Er, Tm, Yb, and Lu.
[0022]
Preferably, R2 is at least one of Dy, Tb, Gd, and Eu.
[0023]
Preferably, the effective ion radius of the rare earth element constituting the first element group is greater than 106 pm.
[0024]
Preferably, when the effective ion radius of the rare earth element constituting the first element group is r1, and the effective ion radius of the rare earth element constituting the second element group is r2, the ratio of r1 and r2 (r2 / R1) satisfies the relationship of 1.007 <r2 / r1 <1.06, and the first element group and the second element group are configured.
[0025]
When the effective ionic radius of Y contained in the first element group is ry, the ratio of ry to r2 (r2 / ry) is preferably 1.007 <(r2 / ry) <1.05. More preferably, the second element group is configured to satisfy the relationship of 1.007 <(r2 / ry) <1.03.
[0026]
Preferably, the ratio of the fourth subcomponent to 100 mol of the main component is 0.1 to 10 mol, more preferably 0.1 to 5 mol (however, the number of moles of the fourth subcomponent is the ratio of R1 alone). ). The ratio of the fifth subcomponent to 100 mol of the main component is preferably 0.01 to 1.25 mol (however, the number of moles of the fifth subcomponent is the ratio of R2 alone). In particular, the DC bias characteristics are improved in these ranges.
[0027]
Preferably, it further has a first subcomponent containing at least one selected from MgO, CaO, SrO and BaO, and the ratio of the first subcomponent to 100 mol of the main component is such that the first subcomponent: 0.1 5 moles. If the ratio of the first subcomponent is too high, the dielectric constant tends to decrease.
[0028]
Preferably, SiO₂A second subcomponent containing a sintering aid of the system is further included, and the ratio of the second subcomponent to 100 mol of the main component is the second subcomponent: 2 to 10 mol. SiO in the second subcomponent₂If the ratio is too low, the firing temperature range tends to be narrow, and if the ratio is too high, the relative permittivity tends to decrease.
[0029]
Preferably, the sintering aid is (Ba, Ca)._xSiO_{2 + x}(Where x = 0.8 to 1.2). If the ratio of BaO or CaO in the second subcomponent is too low, the capacitance changes with time under a DC voltage, and the temperature characteristics and DC bias characteristics of the capacitance tend to deteriorate. If the ratio is too high, The temperature characteristics of the capacity tend to deteriorate.
[0030]
Preferably V₂O₅, MoO₃And WO₃And a ratio of the third subcomponent to 100 mol of the main component is not more than 0.5 mol of the third subcomponent. If the ratio of the third subcomponent is too high, the relative permittivity tends to decrease and the DC bias characteristics tend to deteriorate.
[0031]
Preferably, MnO and Cr₂O₃And a ratio of the sixth subcomponent to 100 moles of the main component is the sixth subcomponent: 0.5 mol or less, more preferably less than 0.25 mol. is there. If the ratio of the sixth subcomponent is too high, the change with time of the capacity under a DC voltage is large, and the temperature characteristics of the capacity tend to deteriorate.
[0032]
Preferably, a diffusion portion containing at least the R1 and R2 exists in each of the dielectric particles constituting the dielectric ceramic composition.
[0033]
The dielectric particle has a ferroelectric portion substantially not including the R1 and R2, and a diffusion portion existing around the ferroelectric portion;
Around the diffusion part, there is a grain boundary segregation part,
The diffusion part and the grain boundary segregation part include at least the R1 and R2, and the respective abundances of R1 and R2 in the diffusion part are MAR1 and MAR2, and each of R1 and R2 in the grain boundary segregation part When the abundances are MBR1 and MBR2, it is preferable that the relations (MBR1 / MBR2)> 1 and (MAR1 / MAR2) <(MBR1 / MBR2) are satisfied.
[0034]
It is preferable that the value of (MAR1 / MAR2) in the diffusion portion gradually decreases from the grain boundary segregation portion side toward the ferroelectric portion side.
[0035]
The electronic component according to the present invention has a dielectric layer made of any one of the above dielectric ceramic compositions. Although it does not specifically limit as an electronic component, A multilayer ceramic capacitor, a piezoelectric element, a chip inductor, a chip varistor, a chip thermistor, a chip resistor, and other surface mount (SMD) chip type electronic components are illustrated.
[0036]
A multilayer ceramic capacitor according to the present invention has a capacitor element body in which dielectric layers composed of the dielectric ceramic composition described above and internal electrode layers are alternately stacked.
[0037]
Preferably, the conductive material included in the internal electrode layer is Ni or a Ni alloy.
[0038]
Preferably, the dielectric layer has an average crystal grain size of 0.5 μm or less, more preferably 0.1 to 0.5 μm. By reducing the average crystal grain size, the relative permittivity tends to decrease, but the change with time of the capacitance under a direct current electric field can be improved.
[0039]
In the present invention, the thickness of the dielectric layer is preferably 5 μm or less, more preferably 4 μm or less. The present invention is particularly effective when the thickness of the dielectric layer is reduced.
[0040]
In addition, the ionic radius described in the present specification is a value based on the document “RD Shannon, Acta Crystallogr., A32, 751 (1976)”.
[0041]
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 (A) is a schematic diagram of dielectric particles, FIG. 2 (B) is a graph showing the concentration distribution of rare earth elements in the dielectric particles,
FIG. 3A to FIG. 3C are graphs showing the relationship between the fifth subcomponent and the relative dielectric constant in the dielectric ceramic composition according to the example of the present invention,
4 (A) to 4 (C) are graphs showing the relationship between the fifth subcomponent and the DC bias characteristics in the dielectric ceramic composition according to the example of the present invention;
FIGS. 5A to 5C are graphs showing the relationship between the fifth subcomponent and the accelerated lifetime of the insulation resistance in the dielectric ceramic composition according to the example of the present invention;
FIGS. 6A to 6C are graphs showing the relationship between the molar ratio of the fourth subcomponent to the fifth subcomponent and the relative dielectric constant in the dielectric ceramic composition according to another embodiment of the present invention,
7 (A) to 7 (C) are graphs showing the relationship between the molar ratio of the fourth subcomponent to the fifth subcomponent and the DC bias characteristics in the dielectric ceramic composition according to another embodiment of the present invention,
FIG. 8A to FIG. 8C are graphs showing the relationship between the molar ratio of the fourth subcomponent to the fifth subcomponent and the accelerated lifetime of the insulation resistance in the dielectric ceramic composition according to the example of the present invention. is there.
[0042]
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).
[0043]
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.
[0044]
The dielectric layer 2 contains the dielectric ceramic composition of the present invention.
In the dielectric ceramic composition, 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),
A fourth subcomponent including an oxide of R1 (wherein R1 is at least one selected from a first element group composed of rare earth elements having an effective ionic radius of 9 coordination of less than 108 pm);
A fifth subcomponent including an oxide of R2 (wherein R2 is at least one selected from a second element group composed of rare earth elements having an effective ionic radius of 108 pm to 113 pm at the time of nine coordination) .
[0045]
The first element group includes Y (107.5 pm), Ho (107.2 pm), Er (106.2 pm), Tm (105.2 pm), Yb (104.2 pm), and Lu (103.2 pm). included. The second element group includes Dy (108.3 pm), Tb (109.5 pm), Gd (110.7 pm), and Eu (112 pm). Sm (113.2 pm), Pm (114.4 pm), Nd (116.3 pm), Pr (117.9 pm), Ce (119.6 pm) and La (121.6 pm) are excluded in the present invention. This is because these Sm, Pm, Nd, Pr, Ce and La are rare earth elements having an effective ionic radius of more than 113 pm at the time of nine coordination. The numbers in parentheses indicate effective ionic radii at the time of nine coordination. The same applies hereinafter. Note that Sc is excluded in the present invention. This is because the effective ionic radius at the time of nine coordination is not defined for Sc.
[0046]
In the present invention, the effective ion radius of the rare earth element constituting the first element group is preferably more than 106 pm. Such first element group includes Y, Ho, and Er. When a rare earth element having a small effective ion radius is used in the first element group, a heterogeneous phase (segregation) may occur. When the heterogeneous phase is generated, the solid solubility in the barium titanate particles is lowered, and the reliability as the capacitor may be lowered eventually.
[0047]
Accordingly, among the rare earth elements constituting the first element group, those having a large effective ion radius are more preferably used, and particularly preferably, the rare earth elements constituting the first element group having an effective ion radius exceeding 107 pm are used. Use. Such a first element group includes Y and Ho. More preferably, it is Y.
[0048]
In the first aspect of the present invention, when the effective ion radius of the rare earth element constituting the first element group is r1, and the effective ion radius of the rare earth element constituting the second element group is r2, r1 It is preferable that the first element group and the second element group are configured so that a ratio (r2 / r1) to r2 satisfies a relationship of 1.007 <r2 / r1 <1.06.
[0049]
In the second aspect of the present invention, the fourth subcomponent preferably contains at least an oxide of Y. The fourth subcomponent may be composed of only Y oxide. Further, the fifth subcomponent includes an oxide of any of Dy, Tb, Gd, and Eu, and more preferably includes an oxide of Tb, Gd. That is, the combination of Y and Gd is most preferable.
[0050]
In the second aspect, when the effective ionic radius of Y is ry and the effective ionic radius of the rare earth elements constituting the second element group is r2, the ratio (r2 / ry) of ry to r2 is 1. The second element group is preferably configured so as to satisfy the relationship of 007 <(r2 / ry) <1.05. Such a second element group includes Dy, Tb, Gd, and Eu.
[0051]
In the dielectric ceramic composition of the present invention, the ratio of each subcomponent to 100 mol of the main component is the fourth subcomponent: more than 0 mol and less than 10 mol, and the fifth subcomponent: more than 0 mol and less than 2 mol, more preferably , The fourth subcomponent: 0.1 to 5 mol, and the fifth subcomponent: 0.01 to 1.25 mol.
Note that the ratio of the fourth subcomponent is not the number of moles of the R1 oxide but the mole ratio of R1 alone. That is, for example, when Y oxide is used as the fourth subcomponent, the ratio of the fourth subcomponent is 1 mol.₂O₃This means that the ratio of Y is not 1 mol, but the ratio of Y is 1 mol. The ratio of the fifth subcomponent is not the number of moles of the R2 oxide but the mole ratio of R2 alone. That is, for example, when the oxide of Tb is used as the fifth subcomponent, the ratio of the fifth subcomponent is 1 mol.₂O₃This means that the ratio of Tb is not 1 mol, but the ratio of Tb is 1 mol.
[0052]
In the dielectric ceramic composition of the present invention, the fourth subcomponent (R1 oxide) exhibits the effect of flattening the capacity-temperature characteristics. When there is too little content of a 4th 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 fourth subcomponents, Y oxides and Ho oxides are preferable, and Y oxides are more preferable because of high effect of improving characteristics and low cost.
[0053]
In the dielectric ceramic composition of the present invention, the fifth subcomponent (R2 oxide) exhibits an effect of improving insulation resistance (IR), IR lifetime (HALT), and DC bias characteristics. However, when the content of the R2 oxide is too large, the capacity-temperature characteristic tends to deteriorate. Among the fifth subcomponents, Dy oxide, Tb oxide, and Gd oxide are preferable because the effect of improving characteristics is high, and Tb oxide is more preferable.
[0054]
In the present invention, in particular, by setting the number of moles of the fifth subcomponent to be more than 0 moles and 2 moles or less, it is possible to improve the relative dielectric constant and improve the DC bias characteristics and HALT.
[0055]
In the present invention, the ratio (M1 / M2) of the number of moles M1 of R1 in the fourth subcomponent to the number of moles M2 of R2 in the fifth subcomponent is 4 <M1 / M2 ≦ 100, more preferably 4 <M1. / M2 ≦ 80, particularly preferably 4 <M1 / M2 ≦ 40.
[0056]
If this ratio M1 / M2 is too low, there is a tendency that a decrease in dielectric constant, a bias characteristic, a lifetime and the like are observed as the dielectric layer is thinned (or the base material is made finer). In particular, when the particle size of the dielectric base material for forming the dielectric layer is 0.5 μm or less, 0.35 μm, or 0.2 μm, the dielectric constant decreases, the bias characteristics, the lifetime, etc. decrease. It tends to be.
[0057]
Further, if the ratio M1 / M2 is too large, the life tends to be reduced.
[0058]
The dielectric ceramic composition of the present invention preferably further includes a first subcomponent containing at least one selected from MgO, CaO, SrO and BaO as necessary. The ratio of the first subcomponent to 100 mol of the main component is preferably 0.1 to 5 mol. When the content of the first subcomponent is too small, the effect of improving the capacity-temperature characteristic tends to be small. On the other hand, if the content is too large, the sinterability deteriorates and the relative dielectric constant tends to decrease. The composition ratio of each oxide in the first subcomponent is arbitrary.
[0059]
The dielectric ceramic composition of the present invention includes SiO.₂It is preferable that a second subcomponent containing a sintering aid of the system is further added. In this case, the sintering aid is (Ba, Ca)._xSiO_{2 + x}(However, it is more preferable that x = 0.8 to 1.2).
[0060]
The ratio of the second subcomponent to 100 mol of the main component is preferably 2 to 10 mol, more preferably 2 to 5 mol. (Ba, Ca) in the second subcomponent_xSiO_{2 + x}In the second subcomponent, BaO and CaO are also included in the first subcomponent, but are complex oxides (Ba, Ca)._xSiO_{2 + x}Has a low reactivity with respect to the main component because of its low melting point. For this reason, it is preferable to add BaO and / or CaO also as the composite oxide. When the content of the second subcomponent is too small, the capacity-temperature characteristic is deteriorated and the IR (insulation resistance) tends to decrease. On the other hand, if the content is too large, the IR life becomes insufficient and the dielectric constant tends to decrease rapidly. (Ba, Ca)_xSiO_{2 + x}X in is preferably 0.8 to 1.2, more preferably 0.9 to 1.1. If x is too small, that is, SiO₂If there is too much, it will react with the barium titanate contained in the main component to deteriorate the 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 the second subcomponent, the ratio of Ba and Ca is arbitrary, and may contain only one.
[0061]
The dielectric ceramic composition of the present invention includes V₂O₅, MoO₃And WO₃It is preferable that a third subcomponent containing at least one selected from the above is further added. The ratio of the third subcomponent to 100 mol of the main component is preferably 0.5 mol or less, more preferably 0.01 to 0.1 mol. The third subcomponent exhibits the effect of flattening the capacity-temperature characteristic above the Curie temperature and the effect of improving the IR lifetime. If the content of the third subcomponent is too small, such an effect becomes insufficient. On the other hand, when there is too much content, IR will fall remarkably. The constituent ratio of each oxide in the third subcomponent is arbitrary.
[0062]
The dielectric ceramic composition of the present invention includes MnO and Cr.₂O₃It is preferable that a sixth subcomponent containing at least one of the above is further added. 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 with respect to 100 mol of the main component 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. In order to improve CR product, it is more preferably less than 0.25 mol.
[0063]
In addition to the above oxides, the dielectric ceramic composition of the present invention includes Al.₂O₃May 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, Al with respect to 100 mol of said main components.₂O₃The ratio is preferably 1 mol or less, and more preferably 1 mol or less of the entire dielectric ceramic composition.
[0064]
Note that, 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.
[0065]
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).
[0066]
The thickness of the dielectric layer 2 is 20 μm or less per layer. The lower limit of the thickness is usually about 0.5 μm. In the present embodiment, even when the thickness of the dielectric layer 2 is reduced to 10 μm or less, and further to 5 μm or less, the relative permittivity is improved, the DC bias characteristics are good, and the accelerated life of the insulation resistance is also improved. The number of laminated dielectric layers 2 is usually about 2 to 1000.
[0067]
For example, as shown in FIG. 2A, the dielectric layer 2 includes dielectric particles 22 and grain boundary segregation portions 24 that exist around the dielectric particles 22. In addition, the code | symbol 25 in the figure shows a grain boundary. The dielectric particle 22 has a ferroelectric portion 222 and a diffusion portion 224 that exists around the ferroelectric portion 222. It is preferable that the ferroelectric portion 222 does not substantially contain the R1 and R2. The term “substantially free of R1 and R2” means that the material contains R1 and R2 to such an extent that the effects of the present invention can be achieved, in addition to the material completely composed of a ferroelectric portion. It is also intended to include.
[0068]
It is preferable that at least the R1 and R2 are dissolved in the diffusion portion 224 and the grain boundary segregation portion 24.
[0069]
More preferably, in the grain boundary segregation portion 24, R1 is more solidly dissolved than R2. That is, it is more preferable that the relationship of (MBR1 / MBR2)> 1 is satisfied when the existing amounts of R1 and R2 in the grain boundary segregation portion 24 are MBR1 and MBR2.
[0070]
More preferably, a large amount of R2 is dissolved in the diffusion portion 224 as it goes in the internal direction of the particle 22 (from the grain boundary segregation portion 24 side to the ferroelectric portion 222 side).
That is, the value of (MAR1 / MAR2) when the respective abundances of R1 and R2 in the diffusion portion 224 are MAR1 and MAR2 is increased from the grain boundary segregation portion 24 side toward the ferroelectric portion 222 side. It is more preferable that it gradually decreases.
[0071]
More preferably, the ratio of the abundance of R1 and R2 in the diffusion portion 224 (MAR1 / MAR2) is greater than the ratio of the abundance of R1 and R2 in the grain boundary segregation portion 24 (MBR1 / MBR2). small. That is, it is more preferable to satisfy the relationship of (MAR1 / MAR2) <(MBR1 / MBR2).
[0072]
By having the dielectric particles 22 having such a structure, in the dielectric ceramic composition, the capacitance temperature dependency in the temperature range of −55 ° C. to 125 ° C. is reduced, and the accelerated life of insulation resistance (high temperature load life: HALT) Is increased.
[0073]
The average crystal grain size of the dielectric particles 22 included in the dielectric layer 2 is not particularly limited, and may be appropriately determined from a range of 0.1 to 5 μm, for example, according to the thickness of the dielectric layer 2 and the like. However, in this embodiment, the average crystal grain size is preferably 0.5 μm or less, and more preferably 0.1 to 0.5 μm. By reducing the average crystal grain size, the relative permittivity tends to decrease, but the change with time of the capacitance under a direct current electric field can be improved.
[0074]
Further, the capacity-temperature characteristic tends to be worse as the dielectric layer 2 per layer is thinner, and worsen as the average crystal grain size is reduced. Further, if the average crystal grain size is made smaller, the IR lifetime becomes longer. From these, the above range is preferable.
[0075]
In the invention according to the first to third aspects, the dielectric ceramic composition of the following aspect is preferable.
[0076]
That is, the dielectric ceramic composition of the present embodiment is
A main component comprising barium titanate;
A first subcomponent comprising MgO;
SiO₂A second subcomponent comprising a sintering aid of the system;
V₂O₅A third subcomponent comprising:
A fourth subcomponent comprising an oxide of R1 (where R1 is Y);
A fifth subcomponent containing an oxide of R2 (wherein R2 is at least one selected from Dy, Tb, Eu and Gd);
A dielectric ceramic composition having a sixth subcomponent containing MnO,
The ratio of each subcomponent to 100 moles of the main component is
1st subcomponent: 0.1-5 mol,
Second subcomponent: 2 to 10 mol,
Third subcomponent: 0.5 mol or less,
4th subcomponent: 0.1-5 mol,
Fifth subcomponent: more than 0 mol and 2 mol or less,
Sixth subcomponent: less than 0.25 mol.
[0077]
However, the number of moles of the fourth subcomponent is the ratio of R1 alone, and the number of moles of the fifth subcomponent is the ratio of R2 alone.
[0078]
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 3 may be appropriately determined according to the application and the like, but is usually 0.1 to 3 μm, particularly preferably about 0.2 to 2.0 μm.
[0079]
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 4 may be determined as appropriate according to the application and the like, but is usually preferably about 10 to 50 μm.
[0080]
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.
[0081]
First, the dielectric ceramic composition powder contained in the dielectric layer paste is prepared, and this is made into a paint to prepare the dielectric layer paste.
[0082]
The dielectric layer paste may be an organic paint obtained by kneading a dielectric ceramic composition powder and an organic vehicle, or may be a water-based paint.
[0083]
As the dielectric ceramic composition powder, the above-described oxides, mixtures thereof, and composite oxides can be used. In addition, various compounds that become the above-described oxides and composite oxides by firing, such as carbonates and An acid salt, a nitrate, a hydroxide, an organometallic compound, or the like can be appropriately selected and mixed for use. What is necessary is just to determine content of each compound in a dielectric ceramic composition powder so that it may become a composition of the above-mentioned dielectric ceramic composition after baking. The particle size of the dielectric ceramic composition powder is usually about 0.1 to 1 [mu] m in average before the coating.
[0084]
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.
[0085]
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.
[0086]
The internal electrode layer paste is prepared by kneading the above-mentioned organic vehicle with various conductive metals and alloys as described above, or various oxides, organometallic compounds, resinates, etc. that become the above-mentioned conductive materials after firing. Prepare.
[0087]
The external electrode paste may be prepared in the same manner as the internal electrode layer paste described above.
[0088]
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.
[0089]
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.
[0090]
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.
[0091]
Before firing, the green chip is subjected to binder removal processing. The binder removal treatment may be appropriately determined according to the type of the conductive material in the internal electrode layer paste. However, when a base metal such as Ni or Ni alloy is used as the conductive material, the oxygen partial pressure in the binder removal atmosphere is 10^-45-10⁵Pa is preferable. When the oxygen partial pressure is less than the above range, the binder removal effect is lowered. If the oxygen partial pressure exceeds the above range, the internal electrode layer tends to oxidize.
[0092]
As other binder removal conditions, the temperature rising rate is preferably 5 to 300 ° C./hour, more preferably 10 to 100 ° C./hour, and the holding temperature is preferably 180 to 400 ° C., more preferably 200 to 350. The temperature holding time is preferably 0.5 to 24 hours, more preferably 2 to 20 hours. Further, the firing atmosphere is preferably air or a reducing atmosphere. As the atmosphere gas in the reducing atmosphere, for example, N₂And H₂It is preferable to use a mixed gas with
[0093]
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^-9-10^-4Pa is preferable. 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.
[0094]
Moreover, the holding temperature at the time of baking becomes like this. Preferably it is 1100-1400 degreeC, More preferably, it is 1200-1350 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.
[0095]
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
[0096]
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.
[0097]
The oxygen partial pressure in the annealing atmosphere is 10^-3Pa or more, especially 10^-210 Pa is preferable. 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.
[0098]
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.
[0099]
As other annealing conditions, the temperature holding time is preferably 0 to 20 hours, more preferably 2 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.
[0100]
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.
[0101]
The binder removal treatment, firing and annealing may be performed continuously or independently.
[0102]
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.
[0103]
According to the present invention, even when the dielectric layer is thinned by making the number of moles of the fourth subcomponent and the number of moles of the fifth subcomponent within a specific range with respect to the main component, In addition to improving the rate, there is little change in capacitance when DC voltage is applied (good DC bias characteristics), the accelerated life of the insulation resistance is improved, and the reliability can be further improved.
[0104]
As mentioned above, although embodiment of this invention has been described, this invention is not limited to the embodiment mentioned above at all, and can be variously modified within the range which does not deviate from the summary of this invention.
[0105]
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.
[0106]
【Example】
Hereinafter, the present invention will be described based on further detailed examples, but the present invention is not limited to these examples.
[0107]
Example 1
A main component material (base material) and subcomponent materials having an average particle size of 0.35 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, as a main component raw material, BaTiO obtained by the hydrothermal synthesis method₃Powder (BT-035 / Sakai Chemical Industry Co., Ltd.) was used.
[0108]
In addition, the raw material of the second subcomponent is 3 moles of (Ba_0.5Ca_0.5) SiO₃Was used. 3 moles of (Ba_0.5Ca_0.5) SiO₃1.5 mol of BaCO₃1.5 moles of CaCO₃And 3 moles of SiO₂Were mixed by wet milling with a ball mill for 16 hours, dried, fired in air at 1150 ° C., and further wet milled with a ball mill for 100 hours.
[0109]
These raw materials were blended so that the composition after firing was as shown in Table 1, wet mixed by a ball mill for 16 hours, and dried to obtain a dielectric raw material. In Table 1, the number of moles of the oxide of R1 and the oxide of R2 in the fourth subcomponent and the fifth subcomponent is the number of moles of R1 alone or R2 alone, respectively.
[0110]
100 parts by weight of the obtained dielectric material, 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 spirit, and 4 parts by weight of acetone are mixed by a ball mill. The paste was made into a dielectric layer paste.
[0111]
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 It knead | mixed with 3 rolls and was made into the paste and obtained the paste for internal electrode layers.
[0112]
Using the obtained dielectric layer paste, a green sheet was formed on a PET film. After the internal electrode paste was printed thereon, the 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.
[0113]
Next, the green chip was cut into a predetermined size and subjected to binder removal processing, firing and annealing under the following conditions to obtain a multilayer ceramic fired body. The binder removal treatment conditions were temperature rising rate: 32.5 ° C./hour, holding temperature: 260 ° C., temperature holding time: 8 hours, and atmosphere: in the air. Firing conditions are: temperature rising rate: 200 ° C./hour, holding temperature: 1260 ° C. or 1280 ° C., temperature holding time: 2 hours, cooling rate: 200 ° C./hour, atmospheric gas: humidified N₂+ H₂Mixed gas (oxygen partial pressure: 10^-6Pa). The annealing conditions were as follows: temperature rising rate: 200 ° C./hour, holding temperature: 1050 ° C., temperature holding time: 2 hours, cooling rate: 200 ° C./hour, atmospheric gas: humidified N₂Gas (oxygen partial pressure: 10^-1Pa). Note that a wetter with a water temperature of 20 ° C. was used for humidifying the atmospheric gas during firing and annealing.
[0114]
Next, after polishing the end face of the obtained multilayer ceramic fired body by sand blasting, In-Ga was applied as an external electrode to obtain samples 1 to 4 of the multilayer ceramic capacitor shown in FIG.
[0115]
The size of the obtained capacitor sample was 3.2 mm × 1.6 mm × 0.6 mm, the number of dielectric layers sandwiched between internal electrode layers was 4, and the thickness of the dielectric layers per layer (interlayer thickness) ) Was about 4.5 μm, and the thickness of the internal electrode layer was 1.2 μm. Further, when the average crystal grain size in the dielectric layer of each sample was examined, it was 0.35 μm. The following characteristics were evaluated for each sample.
[0116]
Dielectric constant (ε), dielectric loss (tan δ), insulation resistance (IR), CR product
Capacitor C and dielectric with respect to a capacitor sample under the conditions of a frequency of 120 Hz and an input signal level (measurement voltage) of 0.625 Vrms / μm using a digital LCR meter (YHP 4274A) at a reference temperature of 20 ° C. The loss tan δ was measured. Then, the relative dielectric constant (no unit) was calculated from the obtained capacitance. Thereafter, the insulation resistance IR after applying DC 20V to the capacitor sample for 60 seconds at 20 ° C. was measured using an insulation resistance meter (R8340A manufactured by Advantest Corporation). The CR product is represented by the product of capacitance (C, μF) and insulation resistance (IR, MΩ). A larger CR product is preferable.
[0117]
The relative dielectric constant ε is an important characteristic for producing a small and high dielectric constant capacitor. In this example, the value of the dielectric constant ε was calculated as an average value of values measured using the number of capacitor samples n = 10. The relative dielectric constant is preferably as large as possible.
[0118]
In this example, the value of the dielectric loss tan δ was calculated as the average value of the values measured using n = 10 capacitor samples. The smaller tan δ is, the better. The results are shown in Table 1. In Table 1 (the same applies to Tables 2 to 5), in the numerical value of insulation resistance (IR), “mE + n” is “m × 10”.^{+ N}"Means.
[0119]
Capacitance temperature characteristics
The capacitance of the capacitor sample was measured with a digital LCR meter (YHP 4274A) under the conditions of a frequency of 120 kHz and an input signal level (measurement voltage) of 0.625 Vrms, and the reference temperature was set to 20 ° C. When the capacitance change rate with respect to temperature (ΔC / C) satisfies the B characteristic of the EIA standard within the temperature range of −25 to 85 ° C., ○ is satisfied, and × is not satisfied. The results are shown in Table 1.
[0120]
DC bias ( DC-Bias ) Characteristics (Capacitance change characteristics when a DC voltage is applied)
A change in permittivity (unit:%) was calculated when a DC voltage was gradually applied to a capacitor sample at a constant temperature (20 ° C.) (measurement condition was 2 V / μm). In this embodiment, the DC bias characteristic is an average value of values measured and calculated using 10 capacitor samples, and is preferably closer to 0. The results are shown in Table 1.
[0121]
High temperature load life (Acceleration life of insulation resistance / HALT)
The high temperature load life was measured by maintaining a DC voltage of 20 V / μm at 180 ° C. with respect to the capacitor sample. This high temperature load life is particularly important when the dielectric layer is thinned. In this example, the time from the start of application until the resistance drops by an order of magnitude was defined as the lifetime, and this was performed for 10 capacitor samples, and the average lifetime was calculated. Longer lifetime is preferable. The results are shown in Table 1.
[0122]
Comparative Example 1
A capacitor sample 5 was produced in the same manner as in Example 1 except that the number of moles of the R2 oxide in the fifth subcomponent was 0 mol%, and the same measurement was performed. The results are shown in Table 1.
[0123]
[Table 1]

[0124]
Evaluation 1
As shown in Table 1, Samples 1 to 4 using the sample of the present example including R1 (fourth subcomponent) and R2 (fifth subcomponent) satisfy the B characteristic, It was found that the relative permittivity and insulation resistance were sufficiently high, the dielectric loss was low, the CR product was good, the DC bias characteristics, and the high temperature load life were also good. It was also confirmed that the sample of this example also satisfies the B characteristic of the EIA standard.
[0125]
On the other hand, as shown in Table 1, the comparative sample containing only R1 (fourth subcomponent) satisfies the B characteristic, but has a dielectric constant, a DC bias characteristic, and a high temperature load life (HALT). Was confirmed to be worse.
[0126]
It is clear from experiments shown in Japanese Patent Application No. 2003-6649 that a sample containing rare earth such as Sc as R2 deteriorates the high-temperature load life or dielectric loss. Further, it has been clarified by an experiment shown in Japanese Patent Application No. 2003-6649 that the temperature characteristic of the capacitance is deteriorated in the sample of the comparative example containing only R2 (the fifth subcomponent).
[0127]
Example 2
As shown in Table 2 below, Examples were used except that the main component material (base material) having an average particle diameter of 0.2 μm was used and the thickness of the dielectric layer per layer (interlayer thickness) was about 3.5 μm. In the same manner as in Example 1, capacitor samples 11 to 14 were prepared and the same measurement was performed. The results are shown in Table 2.
[0128]
Comparative Example 2
A capacitor sample 15 was prepared in the same manner as in Example 2 except that the number of moles of the oxide of R2 in the fifth subcomponent was 0 mol%, and the same measurement was performed. The results are shown in Table 2.
[0129]
[Table 2]

[0130]
Evaluation 2
As shown in Table 2, it was confirmed that ε decreases when the particle size of the base material is reduced and the thickness of the dielectric layer is further reduced as shown in Table 2. However, in Example 2 shown in Table 2, it was confirmed that the CR product was improved as compared with Example 1 shown in Table 1.
[0131]
Example 3
As shown in Table 3 below, Example 1 is different from Example 1 except that the type of R1 in the fourth subcomponent is changed to Ho, Er, Tm, Yb, and Lu, and the type of R2 in the fifth subcomponent is fixed to Tb. Similarly, capacitor samples 21 to 25 were prepared and subjected to the same measurement. The results are shown in Table 3.
[0132]
[Table 3]

[0133]
Evaluation 3
As shown in Table 3, even when Ho, Er, Tm, Yb, and Lu are used instead of Y as R1 (fourth subcomponent), it can be confirmed that the same tendency as in Example 1 is observed. It was. By comparing Table 1 and Table 3, it was confirmed that it is preferable to use Y as R1 from the viewpoint of ε, tan δ, and CR product.
[0134]
Example 4
In the combination of R1 = Y, R2 = Eu, Gd, Tb in Example 2, except that the number of moles of R1 was 4.0 moles and the number of moles of R2 was changed in the range of 0 to 2.1 moles, A capacitor sample was prepared in the same manner as in Example 1, and ε, DC bias characteristics, and HALT were measured in the same manner as in Example 1. The results are shown in FIGS.
[0135]
As shown in FIGS. 3 to 5, it can be confirmed that ε, DC bias characteristics, and HALT are particularly improved when R2 is more than 0 mol and 2 mol or less, preferably 0.1 to 1.5 mol. It was.
[0136]
Example 5
In the combination of R1 = Y, R2 = Eu, Gd, and Tb in Example 2, except that the number of moles of R1 was 4.0 moles and the number of moles of R2 was changed in the range of 0 to 2.5 moles, A capacitor sample was prepared in the same manner as in Example 1, and ε, DC bias characteristics, and HALT were measured in the same manner as in Example 1. The ratio of the number of moles M1 of R1 (Y) to the number of moles M2 of R2 (Eu, Y, Tb) (M1 / M2) is plotted on the horizontal axis, and the measured results of ε, DC bias characteristics, and HALT are plotted on the vertical axis 6 to 8 are shown.
[0137]
As shown in FIGS. 6 to 8, ε, DC bias characteristics, and HALT are particularly improved when M1 / M2 is 4 <M1 / M2 ≦ 100, more preferably 4 <M1 / M2 ≦ 80. Was confirmed.
[0138]
【The invention's effect】
As described above, according to the present invention, even when the dielectric layer is thinned (or the base material is pulverized), the dielectric constant is improved and the change in the capacitance when a DC voltage is applied is small. It is possible to provide a dielectric ceramic composition that has good DC bias characteristics, an improved accelerated life of insulation resistance, and can further improve reliability.
[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. 2A is a schematic diagram of dielectric particles, and FIG. 2B is a graph showing the concentration distribution of rare earth elements in the dielectric particles.
FIG. 3A to FIG. 3C are graphs showing the relationship between the fifth subcomponent and the relative dielectric constant in the dielectric ceramic composition according to the example of the present invention.
4 (A) to 4 (C) are graphs showing the relationship between a fifth subcomponent and DC bias characteristics in a dielectric ceramic composition according to an example of the present invention.
FIGS. 5A to 5C are graphs showing the relationship between the fifth subcomponent and the accelerated lifetime of the insulation resistance in the dielectric ceramic composition according to the example of the present invention.
6 (A) to 6 (C) show the relationship between the molar ratio of the fourth subcomponent to the fifth subcomponent and the relative dielectric constant in the dielectric ceramic composition according to another embodiment of the present invention. It is a graph which shows.
FIGS. 7A to 7C show the relationship between the molar ratio of the fourth subcomponent to the fifth subcomponent and the DC bias characteristics in a dielectric ceramic composition according to another embodiment of the present invention. It is a graph which shows.
FIGS. 8A to 8C are relationships between the molar ratio of the fourth subcomponent to the fifth subcomponent and the accelerated lifetime of the insulation resistance in the dielectric ceramic composition according to the example of the present invention. It is a graph which shows.
[Explanation of symbols]
1 ... Multilayer ceramic capacitor
10 ... Capacitor element body
2 ... Dielectric layer
22 ... Dielectric particles
222 ... Ferroelectric part
224 ... Diffusion part
24 ... Grain boundary segregation part
25 ... Grain boundary
3 ... Internal electrode layer
4 ... External electrode

Claims (19)

A main component consisting of barium titanate,
A first subcomponent consisting of at least one selected from MgO, CaO, SrO and BaO;
A _second subcomponent comprising a SiO ₂ based sintering aid;
A third subcomponent consisting of at least one selected from V ₂ O ₅ , MoO ₃ and WO ₃ ;
Oxide of R1 (note, R1 is at least one effective ionic radius for coordination number 9 is selected from a first element group composed of rare-earth elements less than 108Pm) and a fourth auxiliary component composed of,
Oxides of R2 (although, R2 is at least one effective ionic radius for coordination number 9 is selected from the second element group composed of rare earth elements 108Pm～113pm) and a fifth auxiliary component composed of,
A sixth subcomponent consisting of at least one of MnO and Cr ₂ O ₃ ,
The ratio of each subcomponent to 100 mol of the main component is as follows: first subcomponent: 0.1 to 5 mol, second subcomponent: 2 to 10 mol, third subcomponent: 0.5 mol or less, fourth subcomponent : More than 0 moles and 10 moles or less (however, the number of moles of the fourth subcomponent is a ratio of R1 alone), and the fifth subcomponent: More than 0 moles and less than 2 moles (however, the number of moles of the fifth subcomponent is R2 Independent ratio) , sixth subcomponent: 0.5 mol or less ,
A dielectric ceramic composition characterized in that the ratio (M1 / M2) of the number of moles M1 of R1 to the number of moles M2 of R2 is 10 ≦ M1 / M2 ≦ 100.   2. The dielectric ceramic composition according to claim 1, wherein an effective ion radius of the rare earth element constituting the first element group is more than 106 pm.   When the effective ion radius of the rare earth element constituting the first element group is r1, and the effective ion radius of the rare earth element constituting the second element group is r2, the ratio between r1 and r2 (r2 / r1) 3. The dielectric ceramic composition according to claim 2, wherein the first element group and the second element group are configured to satisfy a relationship of 1.007 <r2 / r1 <1.06.   The dielectric ceramic composition according to any one of claims 1 to 3, wherein the R1 is at least one of Y, Ho, Er, Tm, Yb, and Lu.   The dielectric ceramic composition according to any one of claims 1 to 4, wherein R2 is at least one of Dy, Tb, Gd, and Eu. A main component consisting of barium titanate,
A first subcomponent consisting of at least one selected from MgO, CaO, SrO and BaO;
A _second subcomponent comprising a SiO ₂ based sintering aid;
A third subcomponent consisting of at least one selected from V ₂ O ₅ , MoO ₃ and WO ₃ ;
Oxide of R1 (note, R1 is at least one effective ionic radius for coordination number 9 is selected from a first element group composed of rare-earth elements of less than 108Pm, including at least Y) 4 consisting of Subcomponents,
Oxides of R2 (although, R2 is at least one effective ionic radius for coordination number 9 is selected from the second element group composed of rare earth elements 108Pm～113pm) and a fifth auxiliary component composed of,
A sixth subcomponent consisting of at least one of MnO and Cr ₂ O ₃ ,
The ratio of each subcomponent to 100 mol of the main component is as follows: first subcomponent: 0.1 to 5 mol, second subcomponent: 2 to 10 mol, third subcomponent: 0.5 mol or less, fourth subcomponent : More than 0 moles and 10 moles or less (however, the number of moles of the fourth subcomponent is a ratio of R1 alone), and the fifth subcomponent: More than 0 moles and less than 2 moles (however, the number of moles of the fifth subcomponent is R2 Independent ratio) , sixth subcomponent: 0.5 mol or less ,
A dielectric ceramic composition characterized in that the ratio (M1 / M2) of the number of moles M1 of R1 to the number of moles M2 of R2 is 10 ≦ M1 / M2 ≦ 100.   When the effective ionic radius of Y contained in the first element group is ry and the effective ionic radius of the rare earth element constituting the second element group is r2, the ratio (r2 / ry) of ry to r2 is The dielectric ceramic composition according to claim 6, wherein the second element group is configured to satisfy a relationship of 1.007 <(r2 / ry) <1.05.   When the effective ionic radius of Y contained in the first element group is ry and the effective ionic radius of the rare earth element constituting the second element group is r2, the ratio (r2 / ry) of ry to r2 is The dielectric ceramic composition according to claim 6, wherein the second element group is configured to satisfy a relationship of 1.007 <(r2 / ry) <1.03. A main component consisting of barium titanate,
A first subcomponent consisting of at least one selected from MgO, CaO, SrO and BaO;
A _second subcomponent comprising a SiO ₂ based sintering aid;
A third subcomponent consisting of at least one selected from V ₂ O ₅ , MoO ₃ and WO ₃ ;
A fourth subcomponent consisting of an oxide of R1 (where R1 is Y);
A fifth subcomponent consisting of an oxide of R2 (where R2 is Tb) ;
A sixth subcomponent consisting of at least one of MnO and Cr ₂ O ₃ ,
The ratio of each subcomponent to 100 mol of the main component is as follows: first subcomponent: 0.1 to 5 mol, second subcomponent: 2 to 10 mol, third subcomponent: 0.5 mol or less, fourth subcomponent : More than 0 moles and 10 moles or less (however, the number of moles of the fourth subcomponent is a ratio of R1 alone), and the fifth subcomponent: More than 0 moles and less than 2 moles (however, the number of moles of the fifth subcomponent is R2 Independent ratio) , sixth subcomponent: 0.5 mol or less ,
A dielectric ceramic composition characterized in that the ratio (M1 / M2) of the number of moles M1 of R1 to the number of moles M2 of R2 is 4 <M1 / M2 ≦ 100.   The ratio of the 4th subcomponent with respect to 100 mol of said main components is 0.1-5 mol (however, the number of moles of the 4th subcomponent is a ratio of R1 alone). Dielectric ceramic composition. The dielectric ceramic composition according to claim 1, wherein the sintering aid is (Ba, Ca) _x SiO _{2 + x} (where x = 0.8 to 1.2). The dielectric ceramic composition according to any one of claims 1 to 11 , wherein a diffusion portion including at least the R1 and R2 is present inside each of the dielectric particles constituting the dielectric ceramic composition. Electronic device comprising a dielectric layer composed of a dielectric ceramic composition according to any one of claims 1 to 12. The electronic component according to claim 13 , wherein an average crystal grain size of the dielectric layer is 0.5 μm or less. Electronic component according to claim 13 or 14 the thickness of the dielectric layer is 5μm or less. A multilayer ceramic capacitor having a capacitor element body in which dielectric layers made of the dielectric ceramic composition according to any one of claims 1 to 12 and internal electrode layers are alternately stacked. The multilayer ceramic capacitor according to claim 16 , wherein the conductive material included in the internal electrode layer is Ni or a Ni alloy. The multilayer ceramic capacitor according to claim 16 or 17 , wherein an average crystal grain size of the dielectric layer is 0.5 µm or less. Multilayer ceramic capacitor according to any one of the dielectric layer of thickness ~ claim 16 is 5μm or less 18.

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