JP5153288B2 - Dielectric porcelain composition and electronic component - Google Patents

Description

  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.

  A multilayer ceramic capacitor, which is an example of an electronic component, includes, for example, a ceramic green sheet made of a predetermined dielectric ceramic composition and an internal electrode layer having 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.

  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.

  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. In particular, very high reliability is required for the dielectric ceramic composition in order to reduce the size and capacity of the medium voltage capacitor used at a high rated voltage.

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 1-2 and the like. In any of these techniques, Y ₂ O ₃ was added to improve the accelerated lifetime of insulation resistance (IR). However, as miniaturization and capacity increase rapidly, further improvement in reliability is required.

  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.

  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.

However, in the technique disclosed in Patent Document 3, when an attempt is made to satisfy the X7R characteristic, 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.
In particular, if it is intended to be used as a material for a medium-voltage multilayer ceramic capacitor having a high rated voltage, it has been necessary to sufficiently increase the dielectric thickness to 15 μm or more because of this reliability problem.
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.
Japanese Patent Laid-Open No. 6-84692 JP-A-6-342735 JP-A-10-223471 JP 2000-154057 A

  An object of the present invention is to provide a dielectric ceramic composition that is excellent in reduction resistance during firing, has excellent capacity-temperature characteristics after firing, and has an accelerated accelerated life of insulation resistance. 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 for a medium withstand voltage having a high rated voltage.

In order to achieve the above object, a dielectric ceramic composition according to the first aspect of the present invention comprises:
A main component consisting of barium titanate,
Oxide of R1 (where 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 106pm super 108Pm. However, at least Y) consisting of A fourth subcomponent;
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 the fifth subcomponent to 100 moles of the main component is not less than the ratio of Y;
The ratio of the sixth subcomponent to 100 mol of the main component is the sixth subcomponent: 0.5 mol or less,
Does not contain Sc oxide .

  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 It is preferable that the second element group is configured to satisfy the 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 second element group is preferably configured so as to satisfy the relationship of 1.007 <(r2 / ry) <1.03.

  The total ratio of the fourth subcomponent and the fifth subcomponent to 100 mol of the main component is 10 mol or less (however, the number of moles of the fourth subcomponent and the fifth subcomponent is the ratio of R1 and R2 alone) It is preferable that

  The ratio of each subcomponent with respect to 100 moles of the main component is the fourth subcomponent: 0.1 to 10 moles (however, the number of moles of the fourth subcomponent is the ratio of R1 alone), the fifth subcomponent: 0. It is preferable that it is 1-10 mol (however, the number of moles of the fifth subcomponent is the ratio of R2 alone).

It further has a first subcomponent consisting of 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 the first subcomponent: 0.1 to 5 mol. Preferably there is.

It is preferable to further include a second subcomponent made of a SiO ₂ -based sintering aid, and the ratio of the second subcomponent to 100 mol of the main component is the second subcomponent: 2 to 10 mol. In this case, it is preferable that the sintering aid is (Ba, Ca) _x SiO _{2 + x} (where x = 0.8 to 1.2).

Further comprising a third auxiliary component composed of at least one kind selected from V ₂ O _5, MoO ₃ and WO _3, the ratio of the third subcomponent with respect to 100 moles of the main, third subcomponent: 0.5 mole The following is preferable.

  It is preferable that a diffusion portion containing at least R1 and R2 is present in each of the dielectric particles constituting the dielectric ceramic composition.

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 portion and the grain boundary segregation portion include at least the R1 and R2.
When the respective abundances of R1 and R2 in the diffusion part are MAR1 and MAR2, and the abundances of R1 and R2 in the grain boundary segregation part are MBR1 and MBR2, (MBR1 / MBR2)> 1 And (MAR1 / MAR2) <(MBR1 / MBR2).

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.
In the dielectric ceramic composition according to the first aspect, the invention according to the fourth aspect of the following aspect is preferable.
The dielectric ceramic composition according to the fourth aspect of the present invention is:
A main component consisting of barium titanate,
A first auxiliary component composed of MgO,
A second auxiliary component composed of sintering aid SiO ₂ system,
A third subcomponent consisting of V ₂ O ₅ ;
A fourth subcomponent consisting of an oxide of R1 (where R1 is Y);
A fifth subcomponent consisting of an oxide of R2 (wherein R2 is at least one selected from Dy, Tb and Gd);
And a sixth auxiliary component composed of MnO, a dielectric ceramic composition having,
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,
Sixth subcomponent: less than 0.25 mol.
In a fourth aspect, the total ratio of the fourth subcomponent and the fifth subcomponent to 100 mol of the main component is 10 mol or less (provided that the number of moles of the fourth subcomponent and the fifth subcomponent is R1 and The ratio of R2 alone is preferable.
In a fourth aspect, the ratio of each subcomponent to 100 moles of the main component is the fourth subcomponent: 0.1 to 10 moles (however, the number of moles of the fourth subcomponent is the ratio of R1 alone), 5 subcomponents: 0.1 to 10 moles (however, the number of moles of the fifth subcomponent is preferably a ratio of R2 alone).
In the fourth aspect, it is preferable that a diffusion portion including at least the R1 and R2 exists in each of the dielectric particles constituting the dielectric ceramic composition.
In a fourth aspect, 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 portion and the grain boundary segregation portion include at least the R1 and R2.
When the respective abundances of R1 and R2 in the diffusion part are MAR1 and MAR2, and the abundances of R1 and R2 in the grain boundary segregation part are MBR1 and MBR2, (MBR1 / MBR2)> 1 And (MAR1 / MAR2) <(MBR1 / MBR2).
In the fourth aspect, 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.
In a fourth aspect, the sintering aid is preferably (Ba, Ca) _x SiO _{2 + x} (where x = 0.8 to 1.2).

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.
Particularly preferred electronic components are
An electronic component having a dielectric layer composed of a dielectric ceramic composition,
The dielectric ceramic composition is
A main component consisting of barium titanate,
A first auxiliary component composed of MgO,
A second auxiliary component composed of sintering aid SiO ₂ system,
A third subcomponent consisting of V ₂ O ₅ ;
A fourth subcomponent consisting of an oxide of R1 (where R1 is Y);
A fifth subcomponent consisting of an oxide of R2 (wherein R2 is at least one selected from Dy, Tb and Gd);
And a sixth auxiliary component composed of MnO, has,
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,
Total ratio of the fourth subcomponent and the fifth subcomponent: 10 mol or less (provided that the number of moles of the fourth subcomponent and the fifth subcomponent is the ratio of R1 and R2 alone),
Sixth subcomponent: less than 0.25 mol ,
The ratio of the fifth subcomponent to 100 moles of the main component is not less than the ratio of Y;
Does not contain Sc oxide .
In this preferable electronic component, it is preferable that the sintering aid is (Ba, Ca) _x SiO _{2 + x} (where x = 0.8 to 1.2). This preferable electronic component preferably has a capacitor element body in which the dielectric layers and internal electrode layers mainly composed of a conductive material made of Ni or Ni alloy are alternately laminated.
It is particularly suitable for a medium voltage multilayer ceramic capacitor with a rated voltage of 100V or more.

  In addition, the ionic radius described in the present specification is a value based on the document “RD Shannon, Acta Crystallogr., A32, 751 (1976)”.

  The present inventors proceeded with research on the effect of addition of rare earth elements to barium titanate, and found that adding a plurality of rare earth elements to barium titanate is effective in improving the high temperature load life. Got. 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.

  Therefore, the present inventors have reached the present invention as a result of research on adding a plurality of rare earth elements having different ionic radii, focusing on the ionic radius of rare earth elements to barium titanate.

  In the first aspect of the present invention, a rare earth element group having various effective ionic radii is divided into two element groups with a boundary of 108 pm, and these are added to barium titanate. In the second aspect, the rare earth elements are divided into two element groups, that is, an element group containing Y and a rare earth element group having an effective ion radius of 108 pm or more, and these are added to barium titanate. In the third aspect, the rare earth elements are divided into two element groups, a rare earth element group having an effective ion radius of less than 108 pm and an element group containing Tb, and these are added to barium titanate.

  In the dielectric ceramic composition according to the first to third aspects of the present invention, all have excellent reduction resistance during firing, and after firing, relative permittivity, dielectric loss, insulation resistance, bias characteristics, breakdown voltage In addition to having excellent characteristics such as capacity-temperature characteristics, the accelerated life of the insulation resistance is enhanced.

  Since the electronic component according to the present invention has the dielectric layer composed of the dielectric ceramic composition of the present invention, the accelerated life of the insulation resistance is enhanced, and as a result, the reliability is improved. 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. In particular, according to the fourth aspect, it is possible to provide an electronic component suitable for a multilayer ceramic capacitor or the like having a high rated voltage (for example, 100 V or more) and a medium withstand voltage.

  Note that Patent Document 3 shown in the section of the prior art discloses a dielectric ceramic composition in which a plurality of rare earth elements each selected from two arbitrarily divided element groups are added to barium titanate. Yes. However, this publication does not disclose any inventive idea of dividing rare earth elements into two element groups according to the size of the effective ionic radius at the time of 9-coordination as in the present invention. As a result, in this publication, it is assumed that Sc together with Y belongs to one element group. The same applies to Patent Document 4 shown in the column of the prior art.

  In contrast, the present invention excludes Sc. This is because Sc has an ionic radius that is significantly different from that of other rare earth elements, so that an effective ionic radius at the time of nine coordination is not defined. Therefore, in the present invention, Y does not belong to one element group together with Sc.

  If Sc is used as an element having an effective ion radius of 108 pm or less, it has been confirmed that the X7R characteristic can be satisfied, but the accelerated life of the insulation resistance does not tend to be improved (see sample 24 in Table 3). The reason for this tendency is that the ionic radius of Sc is considerably smaller than that of other rare earth elements including Y, so that the solid solubility in barium titanate particles is larger than that of other rare earth elements. In contrast, it is considered that this is because there is no effect of suppressing segregation of alkaline earth elements.

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. 2A is a photograph showing the segregation state of Mg expressed by EPMA analysis of the microstructure of the dielectric ceramic composition using the sample 9 of this example, and FIG. 2B is the same sample. A photograph showing the segregation state of rare earth elements expressed by EPMA analysis of the microstructure of the dielectric ceramic composition;
3A is a photograph showing the segregation state of Mg expressed by EPMA analysis of the microstructure of the dielectric ceramic composition using the sample 19 of the comparative example, and FIG. 3B is a dielectric using the sample. A photograph showing the segregation state of rare earth elements represented by EPMA analysis of the microstructure of the body porcelain composition;
4A is a photograph showing the segregation state of Mg expressed by EPMA analysis of the microstructure of the dielectric ceramic composition using the sample 24 of the comparative example, and FIG. 4B is a dielectric using the sample. A photograph showing the segregation state of rare earth elements represented by EPMA analysis of the microstructure of the body porcelain composition;
FIG. 5A is a photograph showing the segregation state of Mg expressed by EPMA analysis of the microstructure of the dielectric ceramic composition using the sample 18 of the comparative example, and FIG. 5B is a dielectric using the sample. A photograph showing the segregation state of rare earth elements represented by EPMA analysis of the microstructure of the body porcelain composition;
FIG. 6 shows a photograph of the microstructure of the dielectric ceramic composition using the sample 21-1 having the same composition as that of the sample 21 of this example, but using a BaTiO ₃ particle size of 1 μm, observed by TEM.
FIG. 7A is a schematic diagram schematically showing the fine structure of the dielectric particles contained in the dielectric ceramic composition of FIG. 6, and FIG. 7B is each region of the dielectric particles of FIG. Analysis of the distribution concentration (abundance) of rare earth elements R1 and R2 in FIG.
FIG. 8 is a graph showing the capacitance-temperature characteristics of capacitors using the samples of the examples of the present invention and the comparative examples.

  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).

  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.

The dielectric layer 2 contains the dielectric ceramic composition of the present invention.
In the dielectric ceramic composition according to the first aspect, barium titanate (preferably represented by the composition formula Ba _m TiO _{2 + m} , m is 0.995 ≦ m ≦ 1.010, and the ratio of Ba to Ti Including 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);
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) .

  In the first aspect, 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. (103.2pm) is included. In the first aspect, 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 ion 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.

In the first aspect, it is preferable that the effective ion radius of the rare earth element constituting the first element group is 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.
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.

  In the first aspect, 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 relationship between r1 and r2 The first element group and the second element group are preferably configured so that the ratio (r2 / r1) satisfies a relationship of 1.007 <r2 / r1 <1.06.

In the dielectric ceramic composition according to the second aspect, barium titanate (preferably represented by the composition formula Ba _m TiO _{2 + m} , m is 0.995 ≦ m ≦ 1.010, and the ratio of Ba to Ti Including 0.995 ≦ Ba / Ti ≦ 1.010),
A fourth element 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 less than 108 pm in 9-coordination, including at least Y) Subcomponents,
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) .

  In the second aspect, it is preferable that the first element group is composed of only Y. In the second aspect, the second element group includes Dy, Tb, Gd, and Eu. More preferably, it is Tb. That is, the combination of Y and Tb is most preferable.

  In a second aspect, when the effective ion radius of Y included in the first element group is ry and the effective ion radius of the rare earth element constituting the second element group is r2, the ratio of ry to r2 The second element group is preferably configured so that (r2 / ry) satisfies a relationship of 1.007 <(r2 / ry) <1.05. Such a second element group includes Dy, Tb, Gd, and Eu.

  In a second aspect, when the effective ion radius of Y included in the first element group is ry and the effective ion radius of the rare earth element constituting the second element group is r2, the ratio of ry to r2 The second element group is preferably configured so that (r2 / ry) satisfies a relationship of 1.007 <(r2 / ry) <1.03. Such a second element group includes Dy, Tb, and Gd.

In the dielectric ceramic composition according to the third aspect, barium titanate (preferably represented by the composition formula Ba _m TiO _{2 + m} , m is 0.995 ≦ m ≦ 1.010, and the ratio of Ba to Ti Including 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);
R2 includes 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, but includes at least Tb). 5 subcomponents.

  In a third aspect, the first element group includes Y, Ho, Er, Tm, Yb, and Lu. Moreover, in the 3rd viewpoint, it is preferable that the said 2nd element group is comprised only by Tb.

  In a third aspect, when the effective ion radius of the rare earth element constituting the first element group is r1, and the effective ion radius of Tb contained in the second element group is rtb, the ratio between r1 and rtb The first element group is preferably configured so that (rtb / r1) satisfies the relationship of 1.018 <rtb / r1 <1.062. Such a first element group includes Y, Ho, Er, Tm, Yb, and Lu.

  In a third aspect, when the effective ion radius of the rare earth element constituting the first element group is r1, and the effective ion radius of Tb contained in the second element group is rtb, the ratio between r1 and rtb The first element group is preferably configured so that (rtb / r1) satisfies the relationship of 1.018 <rtb / r1 <1.022. Such a first element group includes Y and Ho.

  In the dielectric ceramic composition of the present invention, the ratio of the fifth subcomponent with respect to 100 moles of the main component is preferably equal to or greater than the ratio of Y. However, if the ratio of the fifth subcomponent is too large, the temperature characteristics of the capacitance may be deteriorated. For this reason, the ratio of the fifth subcomponent to Y is more preferably the fifth subcomponent: Y = 50 to 90%: 10 to 50%, and more preferably the fifth subcomponent: Y = 50 to 70%: 30. ~ 50%.

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: 0.1 to 10 mol and the fifth subcomponent: 0.1 to 10 mol. More preferably, the fourth subcomponent is 0.2 to 5 mol, and the fifth subcomponent is 0.2 to 5 mol.
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 a Y oxide is used as the fourth subcomponent, the ratio of the fourth subcomponent is 1 mol. The ratio of Y ₂ O ₃ is not 1 mol but the ratio of Y is 1 mol. It means that there is. 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 because the ratio of Tb ₄ O ₇ is not 1 mol but the ratio of Tb is 1 mol. It means that.

  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.

  In the dielectric ceramic composition of the present invention, the fifth subcomponent (R2 oxide) exhibits an effect of improving insulation resistance (IR), IR lifetime, and DC bias. 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.

  In the dielectric ceramic composition of the present invention, the total ratio of the fourth subcomponent and the fifth subcomponent to 100 mol of the main component is preferably 10 mol or less, more preferably 5 mol or less. However, the number of moles of the fourth subcomponent and the fifth subcomponent is a ratio of R1 and R2 alone. This is for maintaining good sinterability.

  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 there is too little content of a 1st subcomponent, a capacity | capacitance temperature change rate will become 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.

It is preferable that the dielectric ceramic composition of the present invention further includes a second subcomponent containing a SiO ₂ -based sintering aid. In this case, it is further preferable that the sintering aid is (Ba, Ca) _x SiO _{2 + x} (where x = 0.8 to 1.2).

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. In the case where (Ba, Ca) _x SiO _{2 + x} is contained in the second subcomponent, BaO and CaO in the second subcomponent are also contained in the first subcomponent, but are complex oxides (Ba, Ca). _{Since x} SiO _{2 + x} has a low melting point, it has good reactivity with respect to the main component. Therefore, in this embodiment, it is preferable to add BaO and / or CaO as the composite oxide. When the content of the second subcomponent is too small, the capacity-temperature characteristic is deteriorated and IR (insulation resistance) is lowered. On the other hand, if the content is too large, the IR lifetime becomes insufficient, and a rapid decrease in dielectric constant occurs. _{X in} (Ba, Ca) _x SiO _{2 + x} is preferably 0.8 to 1.2, more preferably 0.9 to 1.1. If x is too small, that is, if SiO ₂ is too much, it reacts with barium titanate contained in the main component 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 the second subcomponent, the ratio of Ba and Ca is arbitrary, and may contain only one.

It is preferable that the dielectric ceramic composition of the present invention further includes a third subcomponent including at least one selected from V ₂ O ₅ , MoO ₃ and WO ₃ . 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.

It is preferable that a sixth subcomponent containing at least one of MnO and Cr ₂ O ₃ is further added to the dielectric ceramic composition of the present invention. 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.

The dielectric ceramic composition of the present invention may contain Al ₂ O _{3 in} addition to the above oxides. Al ₂ O ₃ does not significantly affect the capacity-temperature characteristics, and shows the effect of improving the sinterability, IR and IR life. However, if the content of Al ₂ O ₃ is too large, the sinterability deteriorates and the IR decreases, so the ratio of Al ₂ O ₃ to 100 mol of the main component is preferably 1 mol or less, more preferably, It is 1 mol or less of the whole dielectric ceramic composition.

  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.

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, it is preferable not to use BaTiO ₃ [for example, (Ba, Sr) TiO ₃ ] containing these elements as a 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).

  The thickness of the dielectric layer 2 is usually 40 μm or less, particularly 30 μm or less per layer. The lower limit of the thickness is usually about 0.5 μm. The number of laminated dielectric layers 2 is usually about 2 to 1000.

  For example, as shown in FIG. 7A, the dielectric layer 2 is composed of dielectric particles 22 and grain boundary segregation portions 24 existing 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.

  It is preferable that at least the R1 and R2 are dissolved in the diffusion portion 224 and the grain boundary segregation portion 24.

  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.

  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.

  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).

  By having the dielectric particles 22 having such a structure, the capacitance temperature dependency of the dielectric ceramic composition in the temperature range of −55 ° C. to 125 ° C. is reduced, and the accelerated life (high temperature load life) of the insulation resistance is increased. It is done.

The average crystal grain size of the dielectric particles 22 is not particularly limited, and may be appropriately determined from a range of, for example, 0.1 to 5 μm according to the thickness of the dielectric layer 2 and the like. 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. 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. .
In the dielectric ceramic composition according to the first to third aspects, the invention according to the fourth aspect of the aspect described below is preferable.
The dielectric ceramic composition according to the fourth aspect of the present invention is:
A main component comprising barium titanate;
A first subcomponent comprising MgO;
A _second subcomponent comprising a SiO ₂ -based sintering aid;
A third subcomponent comprising V ₂ O ₅ ;
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 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,
Sixth subcomponent: less than 0.25 mol.
In a fourth aspect, the total ratio of the fourth subcomponent and the fifth subcomponent to 100 mol of the main component is 10 mol or less (provided that the number of moles of the fourth subcomponent and the fifth subcomponent is R1 and The ratio of R2 alone is preferable.
In a fourth aspect, the ratio of each subcomponent to 100 moles of the main component is the fourth subcomponent: 0.1 to 10 moles (however, the number of moles of the fourth subcomponent is the ratio of R1 alone), 5 subcomponents: 0.1 to 10 moles (however, the number of moles of the fifth subcomponent is preferably a ratio of R2 alone).
In the fourth aspect, it is preferable that a diffusion portion 224 including at least R1 and R2 is present in each of the dielectric particles 22 constituting the dielectric ceramic composition.
In a fourth aspect, the dielectric particle 22 includes a ferroelectric portion 222 that does not substantially include the R1 and R2, and a diffusion portion 224 that exists around the ferroelectric portion 222.
Around the diffusion portion 224, there is a grain boundary segregation portion 24,
The diffusion portion 224 and the grain boundary segregation portion 24 include at least the R1 and R2.
When the respective abundances of R1 and R2 in the diffusion portion 224 are MAR1 and MAR2, and the abundances of R1 and R2 in the grain boundary segregation portion 24 are MBR1 and MBR2, respectively (MBR1 / MBR2) It is preferable that the relationship of> 1 and (MAR1 / MAR2) <(MBR1 / MBR2) is satisfied.
In the fourth aspect, it is preferable that the value of (MAR1 / MAR2) in the diffusion portion 224 gradually decreases from the grain boundary segregation portion 24 side toward the ferroelectric portion 222 side. .
In a fourth aspect, the sintering aid is preferably (Ba, Ca) _x SiO _{2 + x} (where x = 0.8 to 1.2).

  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 0.5 to 5 μm, particularly preferably about 0.5 to 2.5 μm.

  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.

  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.

  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.

  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.

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 3 [mu] m in average before the coating.

  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.

  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.

The internal electrode layer paste is obtained 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.
The external electrode paste may be prepared in the same manner as the internal electrode layer paste described above.

  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.

  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.

  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.

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 It is preferable to be ⁻⁴⁵ to 10 ⁵ Pa. 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.

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. The firing atmosphere is preferably air or a reducing atmosphere, and as an atmosphere gas in the reducing atmosphere, for example, a mixed gas of N ₂ and H ₂ is preferably used after being humidified.

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 preferably 10 ⁻⁸ to 10 ⁻⁴ Pa. 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.

  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. Reduction of the body porcelain composition is likely to occur.

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. Further, the firing atmosphere is preferably a reducing atmosphere, and as the atmosphere gas, for example, a mixed gas of N ₂ and H ₂ is preferably used by humidification.

  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.

The oxygen partial pressure in the annealing atmosphere is preferably 10 ⁻³ Pa or more, particularly preferably 10 ^{−2 to} 10 Pa. 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.

  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.

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 the annealing atmosphere gas, for example, humidified N ₂ gas or the like is preferably used.

In the above-described binder removal processing, firing and annealing, for example, a wetter or the like may be used to wet the N ₂ gas or mixed gas. In this case, the water temperature is preferably about 5 to 75 ° C.

  The binder removal treatment, firing and annealing may be performed continuously or independently.

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 conditions of the external electrode paste are preferably, for example, about 10 minutes to 1 hour at 600 to 800 ° C. in a humidified mixed gas of N ₂ and H ₂ . 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.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in various aspects. .

  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.

  Hereinafter, the present invention will be described based on further detailed examples, but the present invention is not limited to these examples.

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, 3 moles of _{(Ba 0.6} Ca 0.4) SiO ₃ was used for the main component material 100 mol. 3 mol of (Ba _0.6 Ca _0.4 ) SiO ₃ was wet-mixed with 1.8 mol of BaCO ₃ , 1.2 mol of CaCO ₃ and 3 mol of SiO ₂ by a ball mill for 16 hours, and after drying It was manufactured by firing in air at 1150 ° C. and further wet pulverizing with a ball mill for 100 hours. 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.
That is, the sample of the present example (samples 8, 9, 16, and 17) includes R1 (fourth subcomponent) and R2 (fifth subcomponent), but the sample of the comparative example (samples 1 to 1). 5, 10, 11, 18) includes only R1 (fourth subcomponent) or R2 (fifth subcomponent).

  Note that Sample 1 further contains Sc. Sample 18 contains Sm. In the sample of this example, R1 (fourth subcomponent) is fixed to Y, and the type of R2 (fifth subcomponent) is changed.

  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.

  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.

  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.

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: 30 ° C./hour, holding temperature: 260 ° C., temperature holding time: 8 hours, and atmosphere: in the air. Firing conditions were: temperature rising rate: 200 ° C./hour, holding temperature: 1280 ° C., temperature holding time: 2 hours, cooling rate: 200 ° C./hour, atmospheric gas: humidified N ₂ + H ₂ mixed gas (oxygen partial pressure: 10 ⁻⁶ Pa). The annealing conditions were: holding temperature: 900 ° C., temperature holding time: 9 hours, cooling rate: 300 ° C./hour, atmospheric gas: humidified N ₂ gas (oxygen partial pressure: 10 ⁻² Pa). Note that a wetter with a water temperature of 35 ° C. was used for humidifying the atmospheric gas during firing and annealing.

  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 a sample of the multilayer ceramic capacitor shown in FIG.

  The size of the obtained capacitor sample is 3.2 mm × 1.6 mm × 0.6 mm, the number of dielectric layers sandwiched between internal electrode layers is 4, the thickness of the dielectric layers per layer (interlayer thickness) ) Was about 11.5 μm or about 9.5 μm, and the thickness of the internal electrode layer was 1.5 μm. The following characteristics were evaluated for each sample.

For a sample of relative permittivity (ε), dielectric loss (tan δ), insulation resistance (IR), and CR product capacitor, at a reference temperature of 25 ° C., a digital LCR meter (YHP 4274A), frequency 1 kHz, input signal The capacitance was measured under the condition of level (measurement voltage) 1 Vrms. Then, the relative dielectric constant (no unit) was calculated from the obtained capacitance. Thereafter, the insulation resistance IR after applying DC 100 V to the capacitor sample for 60 seconds at 25 ° 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). The dielectric loss (tan δ) was measured with a digital LCR meter (4274A manufactured by YHP) at a reference temperature of 25 ° C. under a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms.

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 relative dielectric constant ε was an average value of values measured using the number of capacitor samples n = 10, and preferably 1800 or more.
In this example, the value of the dielectric loss tan δ is an average value of values measured using n = 10 capacitor samples, preferably less than 1.1%, more preferably less than 1.0%. It was good. The results are shown in Table 1.

Capacitance temperature characteristics 1
For the capacitor sample, the capacitance was measured with a digital LCR meter (YHP 4274A) under the conditions of a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms. In the temperature range of −55 to 125 ° C., it is examined whether the capacitance change rate (ΔC / C) with respect to the temperature satisfies the X7R characteristic of the EIA standard. The results are shown in Table 1.

DC bias characteristics (dependence of dielectric constant on DC voltage application)
A change in dielectric constant (unit:%) when a DC voltage was gradually applied to a capacitor sample at a constant temperature (25 ° C.) was calculated (measurement condition was 4 V / μm). In this embodiment, the DC bias characteristic is an average value of values measured and calculated using ten capacitor samples, and preferably within ± (plus or minus) 30%. The results are shown in Table 1. It was confirmed that the representative sample 9 of this example has a stable DC bias characteristic because the dielectric constant hardly decreases even when a high voltage is applied.

High temperature load life (accelerated life of insulation resistance)
The capacitor sample was held at 200 ° C. in a DC voltage application state of 10 V / μm, 17.4 V / μm, and 21 V / μm to measure the high temperature load life. 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. The results are shown in Table 1.

A DC voltage was applied to a breakdown voltage capacitor sample at a heating rate of 100 V / sec. And a leakage current of 100 mA was detected, or a voltage at the time of destruction of the element (breakdown voltage, unit: V / μm) was measured. In this example, the breakdown voltage was an average value of values measured using 10 capacitor samples, and preferably 80 V / μm or more. The results are shown in Table 1.

In Table 1 (including Tables 2 to 6), “mE + n” means “m × 10 ^{+ n} ” in the numerical value of insulation resistance (IR).

  As shown in Table 1, the sample using the sample of this example containing R1 (fourth subcomponent) and R2 (fifth subcomponent) satisfies the X7R characteristic, and has a relative dielectric constant. It was also found that the insulation resistance was sufficiently high, the dielectric loss was satisfactory, the CR product was good, the DC bias characteristics, the high temperature load life, and the breakdown voltage were also good. It was confirmed that the sample of this example satisfies the B characteristic of the EIA standard in addition to the X7R characteristic. In contrast, in the sample using the comparative sample (samples 1 to 5) containing only Sc and R1 (fourth subcomponent), the X7R characteristic is satisfied, but the high temperature load life or dielectric loss is deteriorated. I was able to confirm. In addition, the sample using the comparative sample (sample 11) containing only R2 (fifth subcomponent) does not satisfy even the X7R characteristic, and the characteristics such as dielectric loss, DC bias, and breakdown voltage are deteriorated. I was able to confirm.

Example 2
A sample having the composition shown in Table 2 below (however, the thickness of the dielectric layer per one layer (interlayer thickness) = 9.5 μm) was produced in the same manner as in Example 1. In the samples of this example (samples 21 to 23, 23-1), R1 (fourth subcomponent) and R2 (fifth subcomponent) are included, but the samples of the comparative examples (samples 24, 19, 20) includes only R1 (fourth subcomponent) or R2 (fifth subcomponent). Note that the sample 24 further contains Sc. In the sample of this example, R2 (fifth subcomponent) is fixed to Tb, and the type of R1 (fourth subcomponent) is changed. About these samples, the same measurement as Example 1 was performed. The results are shown in Table 2.

As shown in Table 2, the sample using the sample of the present example including R1 (fourth subcomponent) and R2 (fifth subcomponent) satisfies the X7R characteristic and has a relative dielectric constant. It was also found that the insulation resistance was sufficiently high, the dielectric loss was satisfactory, the CR product was good, the DC bias characteristics, the high temperature load life, and the breakdown voltage were also good. It was confirmed that the sample of this example satisfied the B characteristic of the EIA standard in addition to the X7R characteristic.
On the other hand, the sample using the sample of the comparative example (sample 19) containing only R1 (fourth subcomponent) satisfies the X7R characteristic but confirms that the high temperature load life or the dielectric loss deteriorates. did it. It was confirmed that the dielectric loss and the high temperature load life deteriorated in the sample using the sample of the comparative example (sample 24) containing Sc. It was confirmed that the dielectric loss, DC bias, breakdown voltage, capacity-temperature characteristics, and the like deteriorated in the sample using the comparative sample (sample 20) containing only R2 (fifth subcomponent).
Samples 22, 23 and 23-1 in Table 2 are reference examples.

Microstructure of dielectric ceramic composition 1
Sample 9 of this example (Y: 2 mol, Tb: 2 mol), Sample 19 of comparative example (Y: 4 mol), Sample 24 (Tb: 2 mol, Sc: 2 mol), Sample 18 (Y: 2 mol, Sm: 2 mol) and EPMA analysis of the microstructure of each dielectric ceramic composition, and photographs showing the segregation state of Mg are shown in FIGS. 2 (A), 3 (A), FIG. 4 (A) and FIG. 5 (A), and photographs showing the segregation state of rare earth elements are shown in FIG. 2 (B), FIG. 3 (B), FIG. 4 (B) and FIG. 5 (B). It was.
As shown in FIGS. 3A and 3B, in the sample 19 of the comparative example in which only Y was added as the rare earth element, both segregation of the rare earth element and the alkaline earth element (Mg) was observed. As shown in FIG. 4 (A) and FIG. 4 (B), in the sample 24 of the comparative example in which Tb and Sc are added as rare earth elements, segregation of rare earth elements is small, but segregation of alkaline earth elements is often observed. It was. As shown in FIG. 5 (A) and FIG. 5 (B), in the sample 18 of the comparative example in which Y and Sm are added as rare earth elements, segregation of alkaline earth elements is small, but segregation of rare earth elements is often observed. It was.
On the other hand, as shown in FIGS. 2A and 2B, in the sample 9 of the example in which Y and Tb were added as rare earth elements, segregation of rare earth elements and alkaline earth elements was both suppressed. It was confirmed that

Microstructure of dielectric ceramic composition 2
Although the composition is the same as that of the sample 21 of the present embodiment, a photograph of the microstructure of the dielectric ceramic composition using the sample 21-1 with a BaTiO ₃ particle size of 1 μm is observed with a TEM (Transmission Electron Microscope). As shown in FIG. FIG. 7A is a schematic diagram schematically showing the fine structure of the dielectric particles contained in the dielectric ceramic composition of FIG. 6, and each region of the dielectric particles of FIG. The distribution concentration (abundance) of the rare earth elements R1 and R2 in the sample is analyzed, and a schematic diagram thereof is shown in FIG.
6, 7 </ b> A, and 7 </ b> B, the microstructure of the dielectric ceramic composition is roughly divided into dielectric particles 22 and grain boundary segregation portions 24 existing around the dielectric particles 22. In addition, it was confirmed that the dielectric particle 22 has a ferroelectric portion 222 and a diffusion portion 224 existing around the ferroelectric portion 222.

As shown in FIG. 7B, it was confirmed that the added rare-earth elements R1 and R2 were substantially hardly dissolved in the ferroelectric portion 222.
Further, it was confirmed that the rare earth elements R1 and R2 were both dissolved in the diffusion portion 224 and the grain boundary segregation portion 24.

Furthermore, it was confirmed that R1 was more solidly dissolved in the grain boundary segregation portion 24 than R2. That is, it was confirmed that the relationship of (MBR1 / MBR2)> 1 was satisfied when the respective abundances of R1 and R2 in the grain boundary segregation portion 24 were MBR1 and MBR2.
Furthermore, the ratio of the abundance of R1 and R2 in the diffusion portion 224 (MAR1 / MAR2) is smaller than the ratio of the abundance of R1 and R2 in the grain boundary segregation portion 24 (MBR1 / MBR2). It was confirmed. That is, it was confirmed that the relationship of (MAR1 / MAR2) <(MBR1 / MBR2) was satisfied.

Capacitance temperature characteristics 2
A sample containing Y + Tb (Sample 21), a sample containing Ho + Tb (Sample 22) and a sample containing Er + Tb (Sample 23) were selected as examples of the present invention, and a sample containing Dy + Tb (Sample 20) was selected as a comparative example. The capacity-temperature characteristics of these samples at −55 ° C. to 125 ° C. are shown in FIG. FIG. 8 also shows a rectangular range that satisfies the X7R characteristic. As is apparent from the figure, it can be understood that the samples 21 to 23 of the present example show good capacity-temperature characteristics.
In the sample 20 of the comparative example, a convex curve is drawn with the reference temperature of 25 ° C. as a boundary. When such a curve is drawn, the ferroelectric portion 222 in the dielectric particle 22 described above is drawn. It is considered that Dy and Tb are dissolved in a considerable amount.

Example 3
Samples having the compositions shown in Table 3 below were produced in the same manner as in Example 2. These samples have the same kind and amount of addition of R1 as the fourth subcomponent and the kind and amount of addition of R2 as the fifth subcomponent, but the amount of addition of V ₂ O ₅ is the same as the sample 21 of Example 2. It is different in that it is changed. About these samples, the same measurement as Example 2 was performed. The results are shown in Table 3.

As shown in Table 3, it was confirmed that the high temperature load life tends to be improved by increasing the addition amount of V ₂ O ₅ to a predetermined amount.

Example 4
Samples having the compositions shown in Table 4 below were produced in the same manner as in Example 1. These samples have the same type of R1 as the fourth subcomponent and the type of R2 as the fifth subcomponent in common with the sample 9 of Example 1, but are different in that the addition amounts of R1 and R2 are changed. . About these samples, the same measurement as Example 1 was performed. The results are shown in Table 4. In addition, the sample 21 in Table 2 is also described.

As shown in Table 4, when Y (R1) is large (sample 30), the X7R characteristics are satisfied, but the high temperature load life tends to deteriorate. On the other hand, as Tb (R2) increases (samples 21 and 32), the high temperature load life tends to be improved. However, when Tb increases too much, the capacity-temperature characteristics and the high temperature load life tend to deteriorate.
In addition, the sample 30 in Table 4 is a reference example.

Example 5
Samples having the compositions shown in Table 5 below were produced in the same manner as in Example 1. These samples show the case where a plurality of fourth subcomponents R1 are used (samples 33 to 34). About these samples, the same measurement as Example 1 was performed. The results are shown in Table 5.

  As shown in Table 5, not only when two kinds of rare earth elements are added, but also when three or more kinds of rare earth elements are added, the range defined in the present invention (with respect to the effective ionic radius at the time of nine coordination) is It can be seen that the effects of the present invention can be obtained if the type of rare earth element is selected so as to satisfy.

Example 6
Samples having the compositions shown in Table 6 below were produced in the same manner as in Example 1. These samples show the case where the amount of Mn of the sixth subcomponent is changed (samples 35 to 37). About these samples, the same measurement as Example 1 was performed. The results are shown in Table 6.

  As shown in Table 6, it can be seen that the CR product can be improved by setting the amount of Mn to 0.2 mol, that is, less than 0.25 mol.

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 2A is a photograph showing the segregation state of Mg expressed by EPMA analysis of the microstructure of the dielectric ceramic composition using the sample 9 of this example, and FIG. 2B is the same sample. It is a photograph which shows the segregation state of the rare earth element represented by EPMA analysis of the fine structure of a dielectric ceramic composition. 3A is a photograph showing the segregation state of Mg expressed by EPMA analysis of the microstructure of the dielectric ceramic composition using the sample 19 of the comparative example, and FIG. 3B is a dielectric using the sample. It is a photograph which shows the segregation state of the rare earth element represented by EPMA analysis of the microstructure of the body porcelain composition. 4A is a photograph showing the segregation state of Mg expressed by EPMA analysis of the microstructure of the dielectric ceramic composition using the sample 24 of the comparative example, and FIG. 4B is a dielectric using the sample. It is a photograph which shows the segregation state of the rare earth element represented by EPMA analysis of the microstructure of the body porcelain composition. FIG. 5A is a photograph showing the segregation state of Mg expressed by EPMA analysis of the microstructure of the dielectric ceramic composition using the sample 18 of the comparative example, and FIG. 5B is a dielectric using the sample. It is a photograph which shows the segregation state of the rare earth element represented by EPMA analysis of the microstructure of the body porcelain composition. FIG. 6 is a photograph in which the microstructure of the dielectric ceramic composition using the sample 21-1 having the same composition as the sample 21 of the present example but using a BaTiO ₃ particle size of 1 μm is observed by TEM. FIG. 7A is a schematic diagram schematically showing the fine structure of the dielectric particles contained in the dielectric ceramic composition of FIG. 6, and FIG. 7B is each region of the dielectric particles of FIG. 2 is a diagram schematically showing the distribution concentration (abundance) of rare earth elements R1 and R2 in FIG. FIG. 8 is a graph showing the capacitance-temperature characteristics of capacitors using the samples of the examples of the present invention and the comparative examples.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 10 ... Capacitor element body 2 ... Dielectric layer 22 ... Dielectric particle 222 ... Ferroelectric part 224 ... Diffusion part 24 ... Grain boundary segregation part 25 ... Grain boundary 3 ... Internal electrode layer 4 ... External electrode

Claims (20)

A main component consisting of barium titanate,
Oxide of R1 (where 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 106pm super 108Pm. However, at least Y) consisting of A fourth subcomponent;
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 the fifth subcomponent to 100 moles of the main component is not less than the ratio of Y ;
The ratio of the sixth subcomponent to 100 mol of the main component is the sixth subcomponent: 0.5 mol or less,
A dielectric ceramic composition containing no oxide of Sc . 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 2. The dielectric ceramic composition according to claim 1, 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 2. The dielectric ceramic composition according to claim 1, wherein the second element group is configured to satisfy a relationship of 1.007 <(r2 / ry) <1.03. The total ratio of the fourth subcomponent and the fifth subcomponent to 100 mol of the main component is 10 mol or less (however, the number of moles of the fourth subcomponent and the fifth subcomponent is the ratio of R1 and R2 alone) The dielectric ceramic composition according to any one of claims 1 to 3. The ratio of each subcomponent with respect to 100 moles of the main component is the fourth subcomponent: 0.1 to 10 moles (however, the number of moles of the fourth subcomponent is the ratio of R1 alone), the fifth subcomponent: 0. 5. The dielectric ceramic composition according to claim 1, wherein the dielectric ceramic composition is 1 to 10 moles (however, the number of moles of the fifth subcomponent is a ratio of R2 alone). It further has a first subcomponent consisting of 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 the first subcomponent: 0.1 to 5 mol. The dielectric ceramic composition according to any one of claims 1 to 5. Further comprising a second auxiliary component composed of sintering aid SiO ₂ system, the ratio of the second subcomponent with respect to 100 moles of said main component are the second subcomponent: of claims 1 to 6 from 2 to 10 mol The dielectric ceramic composition according to any one of the above. The dielectric ceramic composition according to claim 7, wherein the sintering aid is (Ba, Ca) _x SiO _{2 + x} (where x = 0.8 to 1.2). Further comprising a third auxiliary component composed of at least one kind selected from V ₂ O _5, MoO ₃ and WO _3, the ratio of the third subcomponent with respect to 100 moles of the main, third subcomponent: 0.5 mole The dielectric ceramic composition according to any one of claims 1 to 8, wherein: The dielectric ceramic composition according to any one of claims 1 to 9 , wherein a diffusion portion including at least the R1 and R2 is present inside each of the dielectric particles constituting the dielectric ceramic composition. 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 portion and the grain boundary segregation portion include at least the R1 and R2.
When the respective abundances of R1 and R2 in the diffusion part are MAR1 and MAR2, and the abundances of R1 and R2 in the grain boundary segregation part are MBR1 and MBR2, (MBR1 / MBR2)> 1 And the dielectric ceramic composition according to claim 10 , satisfying a relationship of (MAR1 / MAR2) <(MBR1 / MBR2). The dielectric ceramic composition according to claim 11 , wherein the value of (MAR1 / MAR2) in the diffusion portion gradually decreases from the grain boundary segregation portion side toward the ferroelectric portion side. An electronic component having a dielectric layer composed of a dielectric ceramic composition,
The dielectric ceramic composition is
A main component consisting of barium titanate,
Oxide of R1 (where 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 106pm super 108Pm. However, at least Y) consisting of A fourth subcomponent;
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 the fifth subcomponent to 100 moles of the main component is not less than the ratio of Y;
The ratio of the sixth subcomponent to 100 mol of the main component is the sixth subcomponent: 0.5 mol or less,
Electronic component not containing Sc oxide .
A multilayer ceramic capacitor having a capacitor element body in which dielectric layers composed of dielectric ceramic compositions and internal electrode layers are alternately laminated,
The dielectric ceramic composition is
A main component consisting of barium titanate,
Oxide of R1 (where 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 106pm super 108Pm. However, at least Y) consisting of A fourth subcomponent;
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 the fifth subcomponent to 100 moles of the main component is not less than the ratio of Y;
The ratio of the sixth subcomponent to 100 mol of the main component is the sixth subcomponent: 0.5 mol or less,
Multilayer ceramic capacitor not containing Sc oxide . The multilayer ceramic capacitor according to claim 14 , wherein the conductive material included in the internal electrode layer is Ni or a Ni alloy. A main component consisting of barium titanate,
A first auxiliary component composed of MgO,
A second auxiliary component composed of sintering aid SiO ₂ system,
A third subcomponent consisting of V ₂ O ₅ ;
A fourth subcomponent consisting of an oxide of R1 (where R1 is Y);
A fifth subcomponent consisting of an oxide of R2 (wherein R2 is at least one selected from Dy, Tb and Gd);
And a sixth auxiliary component composed of MnO, a dielectric ceramic composition having,
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,
The dielectric ceramic composition according to any one of claims 4, 5, 10 , 11, and 12 , wherein the sixth subcomponent is less than 0.25 mol. The dielectric ceramic composition according to claim 16 , wherein the sintering aid is (Ba, Ca) _x SiO _{2 + x} (where x = 0.8 to 1.2). A multilayer ceramic capacitor having a capacitor element body in which dielectric layers composed of a dielectric ceramic composition and internal electrode layers mainly composed of a conductive material made of Ni or Ni alloy are alternately laminated. ,
The dielectric ceramic composition is
A main component consisting of barium titanate,
A first auxiliary component composed of MgO,
A second auxiliary component composed of sintering aid SiO ₂ system,
A third subcomponent consisting of V ₂ O ₅ ;
A fourth subcomponent consisting of an oxide of R1 (where R1 is Y);
A fifth subcomponent consisting of an oxide of R2 (wherein R2 is at least one selected from Dy, Tb and Gd);
And a sixth auxiliary component composed of MnO, has,
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,
Total ratio of the fourth subcomponent and the fifth subcomponent: 10 mol or less (provided that the number of moles of the fourth subcomponent and the fifth subcomponent is the ratio of R1 and R2 alone),
Sixth subcomponent: less than 0.25 mol ,
The ratio of the fifth subcomponent to 100 moles of the main component is not less than the ratio of Y;
Multilayer ceramic capacitor not containing Sc oxide . The multilayer ceramic capacitor according to claim 18 , wherein the sintering aid is (Ba, Ca) _x SiO _{2 + x} (where x = 0.8 to 1.2). The multilayer ceramic capacitor according to claim 18 or 19 , wherein the rated voltage is 100 V or more.

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