JP2005272263A - Dielectric ceramic composition, multilayer ceramic capacitor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric ceramic composition satisfying X8R characteristics with elongated mean time to failure (MTTF), and a multilayer ceramic capacitor provided with the dielectric ceramic composition. <P>SOLUTION: This dielectric ceramic composition comprises barium titanate as the principal component, a first sub-component (at least one of respective oxides of Mg, Ca, Ba and Sr), a second sub-component (an oxide containing 1 mol Si in 1 mol thereof), a third sub-component (at least one of respective oxides of V, Mo and W), a fourth sub-component (an oxide of R<SP>1</SP>which is at least one of Sc, Er, Tm, Yb and Lu), a fifth sub-component (an oxide of R<SP>2</SP>which is at least one of Y, Dy, Ho. Tb, Gd and Eu), a sixth sub-component (at least one of respective oxides of Mn and Cr) and a seventh sub-component (at least one of calcium zirconate and a mixture of Ca oxide and Zr oxide), where the ratio (A/B) of the mole number A of the second sub-component to the total mole number B of the fourth and the fifth sub-components is 0.7 or above. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dielectric ceramic composition, a multilayer ceramic capacitor, and a manufacturing method thereof, and more specifically, a dielectric ceramic composition and a multilayer type that have a long mean time to failure (MTTF) and satisfy X8R characteristics. It relates to ceramic capacitors.

  Multilayer ceramic capacitors as electronic components are widely used as small, large-capacity, and highly reliable electronic components. In recent years, with the miniaturization and high performance of devices, the demand for further miniaturization, larger capacity, lower cost, and higher reliability for multilayer ceramic capacitors has become increasingly severe.

  Multilayer ceramic capacitors are usually obtained by laminating a paste for an internal electrode layer and a paste for a dielectric layer by a sheet method, a printing method, etc., and simultaneously firing the internal electrode layer and the dielectric layer in the laminate. Manufactured.

  As the conductive material for the internal electrode layer, Pd or Pd alloy is generally used. However, since Pd is expensive, a relatively inexpensive base metal such as Ni or Ni alloy has been used. When a base metal is used as the conductive material for the internal electrode layer, the internal electrode layer is oxidized when fired in the atmosphere. Therefore, it is necessary to perform simultaneous firing of the dielectric layer and the internal electrode layer in a reducing atmosphere. . However, when firing in a reducing atmosphere, the dielectric layer is reduced and the specific resistance is lowered. For this reason, non-reducing dielectric materials have been developed.

  However, the multilayer ceramic capacitor using a non-reducing dielectric material has a problem that the insulation resistance (insulation resistance) is significantly deteriorated by the application of an electric field (that is, the IR life is short) and the reliability is low. A solution is required.

  Furthermore, the capacitor is also required to have good temperature characteristics, and in particular, depending on the application, the temperature characteristics are required to be flat under severe conditions. In recent years, multilayer ceramic capacitors have been used in various electronic devices such as an engine electronic control unit (ECU), a crank angle sensor, and an antilock brake system (ABS) module mounted in an engine room of an automobile. . Since these electronic devices are for performing engine control, drive control, and brake control stably, it is required that the circuit has good temperature stability.

  The environment in which these electronic devices are used is expected to decrease to about −20 ° C. or lower in winter in cold regions, and to increase to about + 130 ° C. or higher in summer after engine startup. Recently, there is a tendency to reduce the number of wire harnesses that connect an electronic device and its control target equipment, and the electronic device is sometimes installed outside the vehicle, so the environment for the electronic device has become increasingly severe. Therefore, capacitors used in these electronic devices need to have flat temperature characteristics over a wide temperature range.

As a dielectric ceramic composition having a high dielectric constant and flat capacity-temperature characteristics, BaTiO ₃ is the main component, Nb ₂ O ₅ —Co ₃ O ₄ , MgO—Y, rare earth elements (Dy, Ho, etc.), Bi A composition to which ₂ O ₃ —TiO ₂ or the like is added is known. However, the high dielectric constant material based on BaTiO ₃ can only satisfy the EIA standard X7R characteristics (−55 to 125 ° C., ΔC / C = ± 15% or less), and is used in the severe environment described above. It is not possible to correspond to the electronic device. The electronic device requires a dielectric ceramic composition that satisfies the X8R characteristic (-55 to 150 ° C., ΔC / C = within ± 15%) of the EIA standard.

  The present applicant has already proposed the following dielectric ceramic composition for the purpose of having a high dielectric constant, satisfying X8R characteristics, and enabling firing in a reducing atmosphere (for example, patents). References 1 and 2).

Patent Document 1 includes a main component composed of barium titanate, at least one first subcomponent selected from MgO, CaO, BaO, SrO, and Cr ₂ O ₃ and silicon oxide as a main component. and _{subcomponent,} at least one of the third subcomponent is selected from V ₂ O 5, MoO ₃ and WO _3, oxides of ^{R 1} (where, ^{R 1} is from Sc, Er, Tm, Yb and Lu At least one selected from the group consisting of at least one selected from the group consisting of CaZrO _{3 and} CaO + ZrO ₂ . 1-3 mol, 2nd subcomponent: 2-10 mol, 3rd subcomponent: 0.01-0.5 mol, 4th subcomponent: 0.5-7 mol (however, the number of moles of the 4th subcomponent) , the ratio of by ^{R 1} alone), the fifth subcomponent: 0 < 5 dielectric ceramic composition prepared in raw material consisting of subcomponent ≦ 5 mol is disclosed.

Patent Document 2 discloses a main component composed of barium titanate, a first subcomponent of an AE oxide (where AE is at least one selected from Mg, Ca, Ba, and Sr), and an R oxide. (Wherein R is at least one selected from Y, Dy, Ho and Er), and the ratio of each subcomponent to 100 mol of the main component is such that the first subcomponent: 0 mol < Disclosed is a dielectric ceramic composition made of a raw material comprising a first subcomponent <0.1 mol, a second subcomponent: 1 mol <second subcomponent <7 mol.
Japanese Patent No. 3348081 Patent No. 334003

  According to the dielectric ceramic compositions described in Patent Documents 1 and 2, the X8R characteristic (−55 to 150 ° C., ΔC / C = within ± 15%) of the EIA standard has a high relative dielectric constant and a capacity-temperature characteristic. Satisfactory, and since it does not contain Pb, Bi, Zn, etc., firing in a reducing atmosphere is possible. However, the dielectric ceramic compositions described in the literatures 1 and 2 are not necessarily satisfactory when the dielectric layer is further thinned in order to further reduce the size and increase the capacity of the multilayer ceramic capacitor. Therefore, there is a problem that a dielectric ceramic composition having an average failure life of the length cannot be obtained.

  The present invention has been made in order to solve the above-mentioned problems. The first object of the present invention is to have a capacitance-temperature characteristic when the dielectric layer is further thinned for the purpose of downsizing and increasing the capacity. An object of the present invention is to provide a dielectric ceramic composition that satisfies the X8R characteristics of the EIA standard and has a long average failure life, and a multilayer ceramic capacitor including the dielectric ceramic composition. A second object of the present invention is to provide a method for manufacturing such a multilayer ceramic capacitor. A third object of the present invention is to provide a raw material for producing a dielectric ceramic composition that satisfies the X8R characteristics and has a long average failure life.

In order to achieve the first object, the dielectric ceramic composition of the present invention comprises: (a) barium titanate when the number of moles of each component is expressed relative to the number of moles of barium titanate as 100 moles. And (b) at least one selected from Mg oxide, Ca oxide, Ba oxide and Sr oxide, exceeding 0 in terms of moles when converted to MgO, CaO, BaO and SrO, respectively. A first subcomponent in a molar amount or less, (c) an oxide containing 1 mol of Si atom in 1 mol, and a second subcomponent in an amount of 0.5 to 12 mol in terms of moles converted to the oxide; (d) At least one selected from V oxide, Mo oxide and W oxide, and 0.01 to 0.5 mol in terms of moles converted to V ₂ O ₅ , MoO ₃ and WO ₃ respectively. a third subcomponent, (e) ^{R 1} oxide ^{(R 1} is, Sc, Er, Tm, Yb及At least one) selected from Lu are those containing at least one, and fourth subcomponent 0-7 moles by the number of moles in terms of R ¹ ₂ O _3, respectively, (f) R ² oxide (R ² includes at least one selected from Y, Dy, Ho, Tb, Gd, and Eu), and 0.5 to 9 mol in terms of moles converted to R ² ₂ O ₃ , respectively. 5 subcomponents and (g) at least one selected from a Mn oxide and a Cr oxide, and a sixth subcomponent that is greater than 0 and less than or equal to 0.5 mol in terms of moles converted to MnO and Cr ₂ O ₃ respectively. Component, and (h) a mixture of calcium zirconate and a mixture of Ca oxide and Zr oxide, and a seventh sub-substance of greater than 0 and less than or equal to 5 moles in terms of moles converted to CaZrO ₃ and CaO + ZrO ₂ , respectively. And the second sub-component The ratio (A / B) of the mole number A of the component and the total mole number B obtained by adding the mole number of the fifth subcomponent to the mole number of the fourth subcomponent is 0.7 or more, To do.

According to the present invention, in the barium titanate-based dielectric ceramic composition containing each of the above-described subcomponents, the number of moles A of the second subcomponent and the number of moles of the fourth subcomponent are By setting the ratio (A / B) to the total number of moles B including the number of moles to be 0.7 or more, a dielectric ceramic composition satisfying X8R characteristics and having a long average failure life can be obtained. In the conventional barium titanate-based dielectric ceramic composition, if oxygen defects exist in the dielectric, the oxygen defects move when an electric field is applied, and the dielectric insulation is eventually destroyed. Therefore, when a rare earth element (R ¹ atom, R ² atom) that acts as a donor to prevent the movement of oxygen defects is added, the time until the insulation is broken is increased. However, for example, when a large amount of rare earth elements is added, it becomes burnt, and there is a risk that the life will be reduced. In the present invention, in order to prevent this, the component ratio of the second subcomponent, which is a sintering aid for preventing burnt, and the fourth subcomponent and the fifth subcomponent of the rare earth element acting as a donor is within the above range. It was possible to obtain a dielectric ceramic composition having a long average failure life.

The dielectric ceramic composition of the present invention is a composite oxide in which the second subcomponent is represented by (Ba, Ca) _x SiO _{2 + x} in the dielectric ceramic composition of the present invention. The number of moles is preferably 2 to 10 moles.

  The multilayer ceramic capacitor of the present invention is characterized by having a multilayer body in which dielectric layers made of the dielectric ceramic composition according to the present invention described above and internal electrode layers are alternately stacked.

  According to the present invention, the multilayer ceramic capacitor has a laminated body in which dielectric layers and internal electrode layers made of a dielectric ceramic composition are alternately laminated. Therefore, such a laminated ceramic capacitor satisfies the X8R characteristic and has an average failure life. It will be long.

In order to achieve the second object, the method for producing a multilayer ceramic capacitor of the present invention comprises: (1) barium titanate and / or a compound or mixture that becomes barium titanate upon firing; and (2) MgO, CaO, A first subcomponent comprising at least one oxide selected from BaO and SrO and / or a compound which becomes the oxide upon firing, and (3) an oxide containing 1 mol of Si atom in 1 mol. A second subcomponent, and (4) a third subcomponent composed of at least one oxide selected from V ₂ O ₅ , MoO ₃ and WO ₃ and / or a compound which becomes the oxide by firing, (5 ) At least one oxide represented by the formula R ¹ ₂ O ₃ and / or a compound that becomes the oxide by firing (where R ¹ is an element selected from Sc, Er, Tm, Yb, and Lu) 4th consisting of A subcomponent, and (6) at least one oxide represented by the formula R ² ₂ O ₃ and / or a compound which becomes the oxide by firing (provided that R ² is Y, Dy, Ho, Tb, Gd And an element selected from (Eu) and (Eu), and (7) at least one oxide selected from MnO and Cr ₂ O ₃ and / or a compound that becomes the oxide by firing. subcomponent, (8) CaZrO _3, CaO and a mixture of ZrO _2, compound becomes CaZrO ₃ by firing, and at least one selected from a mixture of compounds that become ZrO ₂ by firing a compound become CaO by calcination A seventh subcomponent consisting of seeds, and the relative number of moles of each component when the number of moles of the barium titanate is 100 moles, the number of moles of each subcomponent is the respective oxide. When converted to First subcomponent: greater than 0 and less than or equal to 7 mol, second subcomponent: 0.5 to 12 mol, third subcomponent: 0.01 to 0.5 mol, fourth subcomponent: 0 -7 mol, fifth subcomponent: 0.5-9 mol, sixth subcomponent: more than 0 and less than 0.5 mol, seventh subcomponent: more than 0 and less than 5 mol, and the second subcomponent A dielectric ceramic composition having a ratio (A / B) of 0.7 or more to the total number of moles B obtained by adding the number of moles of the fifth subcomponent to the number of moles of the fourth subcomponent A preparatory step of preparing a raw material, a dielectric layer forming green sheet made of the dielectric ceramic composition raw material, and a paste layer for forming an internal electrode layer are fired in an alternately laminated state, A firing step of forming a ceramic chip having a green sheet as a dielectric layer and the paste layer as an internal electrode layer; Characterized in that it comprises a reoxidation step of re-oxidizing the dielectric layers in Kkusuchippu.

  According to this invention, the ratio (A / B) of the number of moles A of the second subcomponent that is the sintering aid to the total number of moles B of the fourth subcomponent and the fifth subcomponent of the rare earth element that is the donor. Since a dielectric ceramic composition raw material having a value of 0.7 or more is prepared, a multilayer ceramic capacitor manufactured using such a raw material satisfies the X8R characteristic and has a long average failure life.

The method for manufacturing a multilayer ceramic capacitor according to the present invention is the above-described method for manufacturing a multilayer ceramic capacitor, wherein the second subcomponent is a complex oxide represented by (Ba, Ca) _x SiO _{2 + x} , The auxiliary component is preferably 2 to 10 mol.

In order to achieve the third object, the dielectric ceramic composition raw material of the present invention includes (1) a barium titanate and / or a compound or mixture that becomes barium titanate upon firing, and (2) MgO, CaO, BaO. And a first subcomponent consisting of at least one oxide selected from SrO and / or a compound which becomes the oxide by firing, and (3) a first subcomponent consisting of an oxide containing 1 mol of Si atoms in 1 mol. A second subcomponent, (4) a _third subcomponent comprising at least one oxide selected from V ₂ O ₅ , MoO ₃ and WO ₃ and / or a compound which becomes the oxide upon firing, (5) From at least one oxide represented by the formula R ¹ ₂ O ₃ and / or a compound that becomes the oxide by firing (where R ¹ is an element selected from Sc, Er, Tm, Yb, and Lu) The fourth subcomponent and the equation (6) At least one oxide represented by ² ₂ O ₃ and / or compounds which become the oxides by calcination (wherein, ^{R 2} is, Y, Dy, Ho, Tb , element selected from Gd and Eu) from A fifth subcomponent, (7) at least one oxide selected from MnO and Cr ₂ O ₃ and / or a sixth subcomponent consisting of a compound that becomes the oxide upon firing, and (8) CaZrO ₃ A seventh subcomponent consisting of at least one selected from a mixture of CaO and ZrO ₂ , a compound that becomes CaZrO ₃ upon firing, and a mixture of a compound that becomes CaO upon firing and a compound that becomes ZrO ₂ upon firing. Containing, when the number of moles of each component relative to the number of moles of the barium titanate as 100 moles, the number of moles of each subcomponent is a conversion amount when converted to each oxide, First 1 subcomponent: more than 0 and 7 mol or less, 2nd subcomponent: 0.5-12 mol, 3rd subcomponent: 0.01-0.5 mol, 4th subcomponent: 0-7 mol, 5th sub Component: 0.5 to 9 mol, sixth subcomponent: more than 0 and 0.5 mol or less, seventh subcomponent: more than 0 and less than 5 mol, and the number of moles A of the second subcomponent, The ratio (A / B) to the total number of moles B obtained by adding the number of moles of the fifth subsidiary component to the number of moles of the fourth subsidiary component is 0.7 or more.

  As described above, according to the dielectric ceramic composition and the multilayer ceramic capacitor of the present invention, by adjusting the amounts of the sintering aid for preventing burnt and the rare earth element acting as a donor to the above range. Thus, a dielectric ceramic composition having a long average failure life and satisfying the EIA standard X8R characteristic (−55 to 150 ° C., ΔC / C = ± 15% or less) can be obtained. Therefore, when the dielectric layer is further thinned for the purpose of downsizing and increasing the capacity, its usefulness becomes remarkable, and it is effective particularly in automobile applications used under severe usage environments.

  Moreover, since the dielectric ceramic composition raw material and the dielectric ceramic composition of the present invention do not contain Pb, Bi, Zn, etc., they can be fired in a reducing atmosphere and have a capacity under a direct current electric field. There is also an effect that the change with time is small.

  In addition, according to the method for manufacturing a multilayer ceramic capacitor of the present invention, a multilayer ceramic capacitor having a long average failure life and satisfying X8R characteristics can be manufactured.

  Hereinafter, the dielectric ceramic composition of the present invention, the method for producing the dielectric ceramic composition, the multilayer ceramic capacitor, and the dielectric ceramic composition raw material will be described. Note that the scope of the present invention is not limited by the embodiments described below.

(Multilayer ceramic capacitor and dielectric ceramic composition)
FIG. 1 is a cross-sectional view schematically showing an example of the multilayer ceramic capacitor of the present invention. As shown in FIG. 1, the multilayer ceramic capacitor of the present invention is a multilayer body in which dielectric layers 2 and internal electrode layers 3 are alternately stacked (hereinafter referred to as multilayer dielectric element body 10 or element body 10). )have. A pair of external electrodes 4 are formed at both ends of the laminated dielectric element body 10 to be electrically connected to the internal electrode layers 3 arranged alternately in the element body 10. The shape of the laminated dielectric element body 10 is usually a rectangular parallelepiped, but is not particularly limited. Moreover, although the size is not particularly limited, the long side is usually about 0.6 to 5.6 mm, the short side is about 0.3 to 5.0 mm, and the height is about 0.3 to 1.9 mm. .

The dielectric layer 2 is made of a dielectric ceramic composition. The dielectric ceramic composition includes (a) barium titanate, (b) at least one first subcomponent selected from Mg oxide, Ca oxide, Ba oxide, and Sr oxide, and (c ) A second subcomponent which is an oxide containing 1 mol of Si atom in 1 mol; and (d) at least one third subcomponent selected from V oxide, Mo oxide and W oxide, (e) a fourth subcomponent containing at least one R ¹ oxide (R ¹ is at least one selected from Sc, Er, Tm, Yb and Lu), and (f) an R ² oxide (R ² Is a fifth subcomponent including at least one selected from Y, Dy, Ho, Tb, Gd and Eu), and (g) at least one first selected from Mn oxide and Cr oxide. 6 subcomponents and (h) at least one of a mixture of calcium zirconate and Ca oxide and Zr oxide 7th subcomponent.

  Each component ratio of the dielectric ceramic composition can relatively represent the number of moles of each component with the number of moles of barium titanate being 100 moles.

For example, in the dielectric ceramic composition, when the number of moles of each component is relatively expressed with the number of moles of barium titanate being 100 moles, the first subcomponent is Mg oxide, Ca oxide, Ba oxide and About each Sr oxide, it contains more than 0 and 7 mol or less in terms of moles when converted to MgO, CaO, BaO and SrO, and the second subcomponent is an oxide containing 1 mol of Si atom in 1 mol. 0.5 to 12 moles in terms of the number of moles converted to, and the third subcomponent is a mole converted to V ₂ O ₅ , MoO ₃ and WO ₃ for each of the V oxide, Mo oxide and W oxide. 0.01 to 0.5 mol in number, and the fourth subcomponent is R ¹ for each of R ¹ oxides (R ¹ is at least one selected from Sc, Er, Tm, Yb and Lu). 0 in moles in terms of ¹ ₂ O ₃ Mol contain molar fifth subcomponent, ^{R 2} oxides ^{(R 2} is the Y, Dy, Ho, Tb, at least one selected from Gd and Eu) for ^each, in terms of _R 2 2 _{O 3} The sixth subcomponent contains more than 0 and less than 0.5 mol in terms of the number of moles converted to MnO and Cr ₂ O ₃ for each of the Mn oxide and the Cr oxide. The seventh subcomponent contains calcium zirconate and a mixture of Ca oxide and Zr oxide in a molar number converted to CaZrO ₃ and CaO + ZrO ₂ of more than 0 and 5 mol or less.

  In the present invention, barium titanate may be deviated from the stoichiometric composition, but even in that case, each component is defined with the number of moles of barium titanate deviating from the stoichiometric composition as 100 mol. Relative number of moles. In addition, the oxide of each subcomponent in the dielectric ceramic composition may also be out of the stoichiometric composition, but even in that case, the number of moles of each oxide out of the stoichiometric composition Is expressed as a relative value when the mole number of barium titanate is 100 moles. Further, the number of moles of each component can be determined based on quantitative data of each component atom. This quantitative data can be obtained by various conventionally known methods. For example, quantitative data can be obtained relatively easily by analysis such as fluorescent X-ray analysis or ICP (high frequency inductively coupled plasma spectroscopy).

  The reasons for limiting the contents of the subcomponents are as follows.

  When the content of the first subcomponent is 0 mol (not contained: not contained), the capacity-temperature change rate becomes large. On the other hand, if the content of the first subcomponent exceeds 7 mol, the sinterability deteriorates. In addition, the composition ratio of each oxide in the first subcomponent is arbitrary, and the lower limit of the content of the first subcomponent can be, for example, 0.01 mol.

The second subcomponent acts as a sintering aid for preventing raw burn, and includes, for example, one containing silicon oxide as a main component. When the content of the second subcomponent is less than 0.5 mol, the capacity-temperature characteristic is deteriorated and the insulation resistance (IR) is lowered. On the other hand, when the content of the second subcomponent exceeds 12 moles, the IR life becomes insufficient and the dielectric constant is rapidly lowered. These second subcomponents are SiO ₂ , MO (where M is at least one element selected from Ba, Ca, Sr and Mg), at least one selected from Li ₂ O and B ₂ O _3. It is preferable that it is a complex oxide containing. This second subcomponent mainly acts as a sintering aid, but has an effect of improving the defective rate of the initial insulation resistance when the layer is thinned.

More preferably, the composite oxide of the second subcomponent may be represented by (Ba, Ca) _x SiO _{2 + x} (where x = 0.7 to 1.2). _(Ba, Ca) is Ba atom and Ca atom in the x _{SiO 2 + x} are also included in the first subcomponent, a composite oxide _{(Ba, Ca) x SiO 2} + x has reactivity with the main component has a low melting point It preferably acts as a good sintering aid. The range of _x in (Ba, Ca) _x SiO _{2 + x} is 0.7 to 1.2, more preferably 0.8 to 1.1. If x is less than 0.7, that is, if there are too many Si components relative to the (Ba, Ca) component, it may react with the main component BaTiO ₃ and deteriorate the dielectric properties. On the other hand, if x exceeds 1.2, the melting point becomes high and the sinterability is deteriorated, which is not preferable. The ratio of Ba and Ca is arbitrary and may contain only one. In addition, in this application, IR lifetime is time until the insulation resistance of a capacitor falls an order of magnitude with respect to the value at the time of a measurement start.

  The third subcomponent has the effect of flattening the capacity-temperature characteristic above the Curie temperature of the obtained dielectric ceramic composition and the effect of improving the IR lifetime. If the content of the third subcomponent is less than 0.01 mol, such an effect is insufficient. On the other hand, when the content of the third subcomponent exceeds 0.5 mol, IR is significantly lowered. The constituent ratio of each oxide in the third subcomponent is arbitrary.

  The fourth subcomponent acts as a donor for preventing dielectric breakdown due to the movement of oxygen defects when an electric field is applied (a donor for preventing the movement of oxygen defects). The fourth subcomponent does not necessarily need to be added and may be added in an amount of 0 mol. However, by adding the fourth subcomponent and increasing the amount of addition, the time until breakdown is increased. Can do. The fourth subcomponent has the effect of shifting the Curie temperature of the obtained dielectric ceramic composition to the high temperature side and the effect of flattening the capacity-temperature characteristics. If the content of the fourth subcomponent exceeds 7 mol, the life may be shortened instead of being burnt. Among the fourth subcomponents, Yb oxide is preferable because it has a high characteristic improvement effect and is inexpensive.

  The fifth subcomponent acts as a donor for preventing dielectric breakdown due to the movement of oxygen defects when an electric field is applied (donor for preventing the movement of oxygen defects), as in the fourth subcomponent. . By adding the fifth subcomponent, the time until dielectric breakdown can be lengthened. In addition, the fifth subcomponent exhibits an effect of improving IR and IR lifetime, and has little adverse effect on the capacity-temperature characteristics. When the content of the fifth subcomponent is less than 0.5 mol, it may not be possible to lengthen the time until dielectric breakdown. On the other hand, if the content of the fifth subcomponent exceeds 9 mol, the life may be shortened instead of being burnt. Among the fifth subcomponents, Y oxide is preferable because it has a high effect of improving characteristics and is inexpensive.

The sixth subcomponent has an effect of promoting sintering, an effect of increasing IR, and an effect of improving IR life. In order to sufficiently obtain such an effect, the ratio of the seventh subcomponent with respect to 100 mol of BaTiO ₃ exceeds 0 (preferably lower limit is 0.01 mol) and is 0.5 mol or less. preferable. If the content of the sixth subcomponent exceeds 0.5 mol, the capacity-temperature characteristic may be adversely affected.

The seventh subcomponent has the effect of shifting the Curie temperature of the obtained dielectric ceramic composition to the high temperature side and the effect of flattening the capacity-temperature characteristics. When the content of the seventh subcomponent exceeds 5 mol, the IR accelerated life is remarkably deteriorated and the capacity-temperature characteristic (X8R characteristic) is deteriorated. Although the containing form of calcium zirconate (for example, represented by CaZrO ₃ ) as the seventh subcomponent is not particularly limited, for example, it is contained as a complex oxide such as CaZrO ₃ . Incidentally, this seventh subcomponents, oxides composed of Ca such as CaO, carbonate such as CaCO _3, an organic compound, is blended CaZrO ₃ or the like as a raw material. The ratio of Ca and Zr converted to CaZrO ₃ and CaO + ZrO ₂ is not particularly limited and may be determined so as not to be dissolved in the main component BaTiO ₃ , but the molar ratio of Ca to Zr (Ca / Zr) Is preferably 0.5 to 1.5, more preferably 0.8 to 1.5, and still more preferably 0.9 to 1.1. Note that the IR accelerated life is the time taken for the capacitor to undergo an accelerated test at 200 ° C. under an electric field of 15 V / μm and the insulation resistance to drop by an order of magnitude relative to the value at the start of measurement.

Incidentally, in such a dielectric ceramic composition, by adjusting the fourth content of the subcomponent (rare earth oxide ^{R 1} oxide) and the seventh subcomponent (CaZrO ₃ or those comprising CaO + ZrO _2), Capacitance-temperature characteristics (X8R characteristics) can be flattened, and high temperature accelerated life can be improved. In particular, within the numerical range described above, precipitation of heterogeneous phases is suppressed, and the structure can be made uniform.

In addition to the above oxides, the dielectric ceramic composition may contain an Al oxide (for example, Al ₂ O ₃ ). Al oxide does not significantly affect the capacity-temperature characteristics, and shows the effect of improving the sinterability, IR and IR life. However, if the Al oxide content is too high when converted to the stoichiometric composition of Al ₂ O _3, the sinterability deteriorates and the IR becomes low, so it is converted to the stoichiometric composition of Al ₂ O _3. The content of the Al oxide is preferably 1 mol or less with respect to 100 mol of BaTiO ₃ .

  In the dielectric ceramic composition having such a component ratio, the present invention includes a mole number A of the second subcomponent and a total mole number B obtained by adding the mole number of the fifth subcomponent to the mole number of the fourth subcomponent. It is characterized in that the ratio (A / B) is 0.7 or more. A dielectric ceramic composition having A / B of 0.7 or more can provide a dielectric ceramic composition that satisfies the X8R characteristics and has a long average failure life. If this A / B is less than 0.7, a dielectric ceramic composition having a long average failure life may not be obtained.

In the conventional barium titanate-based dielectric ceramic composition, if oxygen defects exist in the dielectric, the oxygen defects move when an electric field is applied, and the dielectric insulation is eventually destroyed. Therefore, when a rare earth element (R ¹ atom, R ² atom) that acts as a donor to prevent the movement of oxygen defects is added, the time until the insulation is broken is increased. However, for example, when a large amount of rare earth elements is added, it becomes burnt, and there is a risk that the life will be reduced. In order to prevent this, in the present invention, the component ratio of the second subcomponent, which is a sintering aid for preventing raw burning, and the fourth subcomponent and the fifth subcomponent of the rare earth element as a donor is within the above range. By adjusting, a dielectric ceramic composition with a long average failure life could be obtained.

The number of moles A of the second subcomponent is represented by the number of moles converted to an oxide containing 1 mol of Si atom in one mole as described above. For example, the second subcomponent is (Ba, Ca) _x. In the case of a complex oxide represented by SiO _{2 + x} (where x = 0.7 to 1.2), the number of moles of Si atoms in the complex oxide.

The total number of moles B of the fourth subcomponent (R ¹ oxide rare earth oxide) and the fifth subcomponent (R ² oxide rare earth oxide) in total is BTiO ₃ 100 mol. On the other hand, it is preferably 8 mol or less, more preferably 6.5 mol or less. By setting the total number of moles B to 5 moles or less, the sinterability can be kept better.

The Curie temperature (phase transition temperature from ferroelectric to paraelectric) of the dielectric ceramic composition can be changed by selecting the composition of the dielectric ceramic composition, but in order to satisfy the X8R characteristics. Is preferably 120 ° C. or higher, more preferably 123 ° C. or higher. The Curie temperature can be measured by DSC (differential scanning calorimetry) or the like. 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 at least one of Sr, Zr, and Sn is contained as an impurity (for example, about 0.1 mol% or less of the entire dielectric ceramic composition).

  The dielectric particles constituting the dielectric layer constitute the dielectric layer obtained by firing the above-described dielectric ceramic composition. In the present invention, the average particle size of the dielectric particles is It is not particularly limited, and may be appropriately determined from the range of, for example, 0.1 to 3 μm according to the thickness of the dielectric layer. Specifically, it is particularly effective when the average particle size is 0.1 to 0.5 μm, the IR life is prolonged, and the change with time of the capacity under a direct current electric field can be reduced. In the present invention, the average particle diameter of the dielectric particles is determined by a code method.

  Further, when the capacitance-temperature characteristic satisfies the X8R characteristic of the EIA standard, the manufactured multilayer ceramic capacitor is preferably used as an electronic component for equipment used in an environment of 80 ° C. or higher, particularly 125 to 150 ° C. It shows what can be done. In such a temperature range, the capacitance temperature characteristic satisfies the EIAJ standard R characteristic, and further satisfies the EIA standard X8R characteristic (−55 to 150 ° C., within ΔC / C = ± 15%). I mean. EIAJ standard B characteristics [capacity change rate within ± 10% at −25 to 85 ° C. (reference temperature 20 ° C.)] and EIA standard X7R characteristics (−55 to 125 ° C., ΔC = within ± 15%) at the same time It is possible to be satisfied. In addition, it is said that the capacity change rate after 1000 hours is excellent when the manufactured multilayer ceramic capacitor is applied with a DC voltage of, for example, 7 V / μm in a temperature environment of 85 ° C. It means within 10%.

  Various conditions such as the number and thickness of the dielectric layers 2 may be appropriately determined according to the purpose and application. However, the thickness of the dielectric layer 2 is usually 30 μm or less, and from the viewpoint of reducing the size and increasing the capacity. Therefore, the thickness of the dielectric layer 2 is preferably 10 μm or less. A multilayer ceramic capacitor having a thinned dielectric layer as described above can achieve downsizing and large capacity, and by specifying the average particle diameter of the dielectric particles constituting the dielectric layer, etc. It is effective for improving capacity-temperature characteristics. Although the lower limit of the thickness of the dielectric layer is not particularly limited, it is about 0.5 μm if it is given. Moreover, the number of laminated dielectric layers is usually about 2 to 1000.

  The internal electrode layers 3 are provided alternately with the dielectric layers 2 described above, and are laminated so that the respective end faces are alternately exposed on the surfaces of the two opposite end portions of the laminated dielectric element body 10. The pair of external electrodes 4 are formed at both ends of the multilayer dielectric element body 10 and are connected to the exposed end surfaces of the alternately arranged nickel internal electrode layers 3 to constitute a multilayer ceramic capacitor.

  The internal electrode layer 3 is made of a nonmetallic conductive material that substantially acts as an electrode. Specifically, Ni or Ni alloy is preferable. The Ni alloy is preferably an alloy of Ni or one or more of Mn, Cr, Co, Al, W, and the like with Ni, and the Ni content in the alloy is preferably 95% by weight or more. Further, Ni or Ni alloy may contain 0.1% by weight or less of various trace components such as P, C, Nb, Fe, Cl, B, Li, Na, K, F, and S. Various conditions such as the number and thickness of the internal electrode layers 3 may be appropriately determined according to the purpose and application, but the thickness is usually preferably about 0.1 μm to 5 μm, preferably 0.5 μm to 2.5 μm. Is more preferable.

  The external electrodes 4 are electrodes that are electrically connected to the internal electrode layers 3 arranged alternately in the laminated dielectric element body 10, and are formed as a pair at both ends of the laminated dielectric element body 10. As the external electrode 4, at least one of Ni, Pd, Ag, Au, Cu, Pt, Rh, Ru, Ir, or an alloy thereof can be usually used. Usually, Cu, Cu alloy, Ni, Ni alloy or the like, Ag, Ag—Pd alloy, In—Ga alloy or the like is 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 200 μm.

(Manufacturing method of multilayer ceramic capacitor)
In the multilayer ceramic capacitor 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 an external electrode is printed or transferred. It is manufactured by baking.

  More specifically, a preparation step of preparing the dielectric ceramic composition raw material described above, a dielectric layer forming green sheet and an internal electrode paste prepared from the dielectric layer paste containing the dielectric ceramic composition raw material A firing step in which the prepared paste layers for forming the internal electrode layers are fired in an alternately laminated state to form a ceramic chip in which the green sheet becomes a dielectric layer and the paste layer becomes an internal electrode layer; And a reoxidation step of reoxidizing the dielectric layer in the ceramic chip. Hereinafter, the manufacturing method will be specifically described.

  The dielectric layer paste is a paint obtained by kneading a dielectric ceramic composition raw material and an organic vehicle, and may be an organic paint or a water-based paint.

  As the dielectric ceramic composition raw material, the above-mentioned oxide, a mixture thereof, or a composite oxide can be used. In addition, various compounds that become the above-described oxide or composite oxide upon firing, such as carbonates and oxalic acid. It can be appropriately selected from salts, nitrates, hydroxides, organometallic compounds, and the like, and can be used as a mixture. The content of each oxide in the dielectric ceramic composition raw material and / or the compound that becomes an oxide by firing may be determined so as to be the composition of the dielectric ceramic composition described above after firing. As the dielectric ceramic composition material, a powder having an average particle size of about 0.1 to 3 μm is usually used.

More specifically, (1) barium titanate and / or a compound or mixture that becomes barium titanate upon firing, and (2) at least one oxide selected from MgO, CaO, BaO and SrO and / or firing. A first subcomponent composed of a compound that becomes the oxide, (3) a second subcomponent composed of an oxide containing 1 mol of Si atom in 1 mol, (4) V ₂ O ₅ , MoO ₃ and WO _{A third} subcomponent composed of at least one oxide selected from ₃ and / or a compound that becomes the oxide by firing, (5) at least one oxide represented by the formula R ¹ ₂ O ₃ , and And / or a fourth subcomponent consisting of a compound that becomes the oxide upon firing (where R ¹ is an element selected from Sc, Er, Tm, Yb, and Lu), and (6) Formula R ² ₂ O ₃ At least one oxide represented and Or a compound forming the oxide upon firing (wherein, ^{R 2} is, Y, Dy, Ho, Tb , element selected from Gd and Eu) and the fifth auxiliary component composed of, (7) MnO and _Cr 2 _{O 3} A sixth subcomponent consisting of at least one oxide selected from: and / or a compound that becomes the oxide upon firing; and (8) a mixture of CaZrO ₃ , CaO and ZrO ₂ , a compound that becomes CaZrO ₃ upon firing. And a seventh subcomponent consisting of at least one compound selected from a mixture of a compound that becomes CaO upon firing and a compound that becomes ZrO ₂ upon firing, and the number of moles of the barium titanate is 100 moles. In terms of the relative number of moles, the number of moles of each subcomponent is a conversion amount when converted into each oxide, and the first subcomponent is more than 0 and not more than 7 moles, and the second subcomponent is 0. .5-12 3rd subcomponent: 0.01-0.5 mol, 4th subcomponent: 0-7 mol, 5th subcomponent: 0.5-9 mol, 6th subcomponent: more than 0, 0.5 mol Hereinafter, the seventh subcomponent: more than 0 and less than or equal to 5 moles, the mole number A of the second subcomponent, and the total mole number B of the mole number of the fourth subcomponent plus the mole number of the fifth subcomponent A dielectric ceramic composition raw material having a ratio (A / B) of 0.7 or more is used.

  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. Moreover, 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, a dispersant, or the like is dissolved in water and a dielectric ceramic composition raw 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, etc. may be used.

  The internal electrode layer paste is prepared by kneading the above-mentioned organic vehicle with various conductive metals made of various dielectric metals and alloys, or various oxides, organometallic compounds, resinates, etc. that become the above-mentioned conductive materials after firing. Prepare. The external electrode paste may be prepared in the same manner as the internal electrode layer paste described above.

  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 process may be performed under normal conditions. However, when a base metal such as Ni or Ni alloy is used as the conductive material of the internal electrode layer, the heating rate is preferably 5 to 300 ° C./hour in an air atmosphere. More preferably, the temperature is 10 to 100 ° C./hour, the holding temperature is preferably 180 to 400 ° C., more preferably 200 to 300 ° C., and the temperature holding time is preferably 0.5 to 24 hours, more preferably 5 to 20 hours. To do.

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 ⁻¹² atm. 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 1200-1360 degreeC, More preferably, it is 1200-1320 degreeC. If the holding temperature is lower than the above range, the densification becomes insufficient. If the holding temperature is higher than the above range, the electrode temperature is interrupted due to abnormal sintering of the internal electrode layer, the capacity temperature characteristic deteriorates due to diffusion of the constituent material of the internal electrode layer, and the dielectric Reduction of the body porcelain composition is likely to occur.

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 after being humidified.

  When firing in a reducing atmosphere, it is preferable to anneal the multilayer dielectric 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 ⁻⁶ atm or more, particularly 10 ⁻⁵ to 10 ⁻⁴ atm. 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. In addition, you may comprise annealing only from a temperature rising process and a temperature falling 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 6 to 10 hours, and the cooling rate is preferably 50 to 500 ° C./hour, more preferably 100 to 300 ° C./hour. . Further, as the atmosphere gas for annealing, 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, mixed gas, or the like. 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. When these are performed continuously, after removing the binder, the atmosphere is changed without cooling, and then the temperature is raised to the holding temperature at the time of baking to perform baking, and then cooled to reach the annealing holding temperature. Sometimes it is preferable to perform annealing by changing the atmosphere. On the other hand, when performing these independently, at the time of firing, after raising the temperature under N ₂ gas atmosphere with N ₂ gas or wet to the holding temperature of the binder removal processing, further continuing the heating to change the atmosphere Preferably, after cooling to the holding temperature at the time of annealing, it is preferable to change to the N ₂ gas or humidified N ₂ gas atmosphere again and continue cooling. In annealing, the temperature may be changed to a holding temperature in an N ₂ gas atmosphere, and then the atmosphere may be changed, or the entire annealing process may be a humidified N ₂ gas atmosphere.

The laminated dielectric element main body obtained as described above is subjected to end face 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 or the like by soldering or the like and used for various electronic devices.

  The multilayer ceramic capacitor and the method for manufacturing the same according to the present invention have been described above. However, the present invention is not limited to these embodiments, and can be implemented in various modes without departing from the scope of the present invention. Of course you get.

  The present invention will be described in detail by the following experimental examples and comparative examples. However, the present invention is not limited to the following description.

(Preparation of sample 1)
First, as starting materials for producing a dielectric material, main component materials (BaTiO ₃ ) and first to seventh subcomponent materials each having an average particle diameter of 0.1 to 1 μm were prepared. Incidentally, those for the main component BaTiO _3, which weighed BaCO ₃ and TiO _2, respectively, a ball mill and mixed for about 16 hours wet using, after dried, and calcined in air at a temperature of 1100 ° C. Further, a similar product was obtained by using a product prepared by wet pulverizing for 16 hours with a ball mill. Furthermore, BaTiO ₃ being the main component, hydrothermal synthesis powder was obtained those same be used those produced by oxalate method, or the like.

Carbonate (first subcomponent: MgCO ₃ , sixth subcomponent: MnCO ₃ ) is used as the raw material for MgO and MnO, and oxide (second subcomponent: (Ba _0.6 Ca _{0. 4} ) SiO ₃ , third subcomponent: V ₂ O ₅ , fourth subcomponent: Yb ₂ O ₃ , fifth subcomponent: Y ₂ O ₃ , seventh subcomponent: CaZrO ₃ ) were used. Each subcomponent is expressed in terms of the conversion amount when the number of moles of each subcomponent is converted to the above oxides when the number of moles of each component is relatively expressed with the number of moles of BaTiO ₃ being 100 moles. The mixture was adjusted to the number of moles shown in FIG. 1 and wet mixed by a ball mill for 16 hours and dried to obtain a dielectric ceramic composition raw material. In addition, (Ba _0.6 Ca _0.4 ) SiO ₃ as the second subcomponent is wet mixed with BaCO ₃ , CaCO ₃ and SiO ₂ for 16 hours by a ball mill, dried, and fired at 1150 ° C. in the air. Furthermore, it was manufactured by wet grinding with a ball mill for 100 hours. In addition, CaZrO ₃ as the seventh subcomponent is produced by wet mixing CaCO ₃ and ZrO ₂ with a ball mill for 16 hours, drying, firing in air at 1150 ° C., and further wet pulverizing with a ball mill for 24 hours. did.

  100 parts by weight of the dried dielectric ceramic composition raw material thus obtained, 4.8 parts by weight of acrylic resin, 40 parts by weight of methylene chloride, 20 parts by weight of ethyl acetate, 6 parts by weight of mineral spirits, Then, 4 parts by weight of acetone was mixed with a ball mill to form a paste, and a dielectric layer paste was obtained.

  Next, 100 parts by weight of Ni particles having an average particle diameter of 0.4 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 The paste was kneaded with a roll to obtain an internal electrode layer paste. Note that a paste-like In—Ga alloy was prepared for the external electrode.

  Next, a 4.5 μm-thick green sheet was formed on the PET film using the dielectric layer paste, and the internal electrode layer paste was printed thereon, and then the green sheet was peeled from the PET film. Next, these green sheets and protective green sheets (not printed with internal electrode layer paste) were laminated and pressure-bonded to obtain green chips. The number of sheets having internal electrodes was five.

Next, the green chip was cut into a predetermined size and subjected to binder removal processing, firing and annealing to obtain a fired body as a multilayer ceramic chip. The binder removal treatment was performed under conditions of a temperature rising time of 32.5 ° C./hour, a holding temperature of 260 ° C., a holding time of 8 hours, and an air atmosphere. In addition, the firing is performed at a temperature rising rate of 200 ° C./hour, a holding temperature of 1320 ° C., a holding time of 2 hours, a cooling rate of 200 ° C./hour, and a humidified N ₂ + H ₂ mixed gas atmosphere (oxygen partial pressure is 10 ⁻¹² atm). Performed under conditions. The annealing was performed under the conditions of a holding temperature of 1050 ° C., a temperature holding time of 2 hours, a cooling rate of 200 ° C./hour, and a humidified N ₂ gas atmosphere (oxygen partial pressure was 10 ⁻⁵ atm). A wetter with a water temperature of 20 ° C. was used for humidifying the atmospheric gas during firing and annealing.

  Next, after polishing the end face of the multilayer ceramic chip by sandblasting, a paste-like In—Ga alloy was applied to the end face to form an external electrode, thereby obtaining a multilayer ceramic capacitor sample. The size of each obtained sample is 3.2 mm × 1.6 mm × 0.6 mm, the number of dielectric layers sandwiched between the internal electrode layers is 5, and the thickness of each dielectric layer is 3 The thickness per internal electrode layer was 1.0 μm.

  The obtained multilayer ceramic capacitor sample was not reduced even when fired in a reducing atmosphere, and the nickel used as the internal electrode was not oxidized to such an extent that IR failure occurred.

(Preparation of samples 2 to 17)
Multilayer ceramic capacitors of Samples 2 to 17 were fabricated in the same manner as above except that the component composition of the dielectric ceramic composition raw material was changed to that shown in Table 1 in the fabrication of Sample 1.

  None of the obtained multilayer ceramic capacitor samples were reduced when fired in a reducing atmosphere, and nickel used as an internal electrode was not oxidized to such an extent that an IR defect occurred.

(Evaluation methods and results for each characteristic)
For the produced multilayer ceramic capacitors of Samples 1 to 17, the number of moles of the fifth subcomponent was added to the number of moles A of the second subcomponent representing the blending ratio of the sintering aid and the number of moles of the fourth subcomponent. The ratio (A / B) to the total number of moles B was measured, and the MTTF (average failure life) of each obtained sample was measured and evaluated. The results are shown in Table 1. As an evaluation standard in the present application, a MTTF of 10 hours or more is indicated as ◯, and an MTTF less than 10 hours is indicated as ▲.

  MTTF (average failure life) was calculated from the Weibull function based on the results of a high acceleration life test (HALT) under the conditions of an atmospheric temperature of 200 ° C. and an applied voltage of 15 V / μm. It is expressed by average life time (hour: hr).

  The capacity-temperature characteristic was also measured. This capacitance-temperature characteristic measures the change rate (%) of the capacitance in a temperature environment of 150 ° C. where the capacitance-temperature characteristic is worst in the temperature range of −55 to 150 ° C. with respect to the obtained capacitor sample. It was evaluated by doing. The capacitance was measured using an LCR meter under the conditions of a frequency of 1 kHz and an input signal level of 1 Vrms. For the measurement results, evaluation was made based on whether or not the X8R characteristics (−55 to 150 ° C., ΔC = within ± 15%) were satisfied. The results are shown in Table 1. In any of Samples 1 to 17, the capacitance change rate was within 15%, and it was confirmed that the X8R characteristics were satisfied.

  As is clear from the results in Table 1, among samples 1 to 17, samples 2 to 9 had an MTTF of 10 hours or more, and good results were obtained. On the other hand, for samples 1 and 10-17, the MTTF was less than 10 hours.

It is a schematic cross section which shows an example of the multilayer ceramic capacitor of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 2 ... Dielectric layer 3 ... Internal electrode layer 4 ... External electrode 10 ... Multilayer dielectric element body

Claims (6)

When the number of moles of each component is represented relative to the number of moles of barium titanate as 100 moles,
(a) barium titanate and (b) at least one selected from Mg oxide, Ca oxide, Ba oxide and Sr oxide, and moles when converted to MgO, CaO, BaO and SrO, respectively A first subcomponent of greater than 0 and less than or equal to 7 moles, and (c) an oxide containing 1 mole of Si atoms in 1 mole, 0.5 to 12 moles in terms of moles converted to the oxide A second subcomponent, and (d) at least one selected from V oxide, Mo oxide, and W oxide, and 0.01 mol in terms of V ₂ O ₅ , MoO _3, and WO ₃ , respectively. -0.5 mol of the third subcomponent, and (e) R ¹ oxide (R ¹ is at least one selected from Sc, Er, Tm, Yb and Lu), 0 to 7 moles of the fourth subcomponent in moles converted to R ¹ ₂ O ₃ , respectively, and (f) R ² It contains at least one oxide (R ² is at least one selected from Y, Dy, Ho, Tb, Gd and Eu), and 0.5 to 0.5 in terms of moles converted to R ² ₂ O ₃ , respectively. 9 mol of the fifth subcomponent and (g) at least one selected from Mn oxide and Cr oxide, each exceeding 0 and 0.5 mol or less in terms of moles converted to MnO and Cr ₂ O ₃ And (h) at least one of a mixture of calcium zirconate and Ca oxide and Zr oxide, each having a molar number of more than 0 and not more than 5 mol in terms of CaZrO ₃ and CaO + ZrO ₂ . Containing a seventh subcomponent,
The ratio (A / B) between the number A of moles of the second subcomponent and the total number of moles B of the number of moles of the fifth subcomponent added to the number of moles of the fourth subcomponent is 0.7 or more. A dielectric ceramic composition characterized by the above. 2. The dielectric according to claim 1, wherein the second subcomponent is a composite oxide represented by (Ba, Ca) _x SiO _{2 + x} , and the number of moles of the composite oxide is 2 to 10 mol. Body porcelain composition.   A multilayer ceramic capacitor comprising a laminate in which dielectric layers made of the dielectric ceramic composition according to claim 1 or 2 and internal electrode layers are alternately laminated. (1) barium titanate and / or a compound or mixture that becomes barium titanate upon firing, and (2) at least one oxide selected from MgO, CaO, BaO and SrO and / or firing to the oxide. Selected from the following: a first subcomponent consisting of a compound comprising: (3) a second subcomponent consisting of an oxide containing 1 mole of Si atoms in 1 mole; and (4) V ₂ O ₅ , MoO ₃ and WO ₃ A third subcomponent composed of at least one oxide and / or a compound that becomes the oxide by firing, and (5) at least one oxide represented by the formula R ¹ ₂ O ₃ and / or by firing. A fourth subcomponent consisting of a compound to be the oxide (where R ¹ is an element selected from Sc, Er, Tm, Yb and Lu), and (6) at least represented by the formula R ² ₂ O ₃ By one oxide and / or firing Compounds that become the oxides (where, ^{R 2} is, Y, Dy, Ho, Tb, element selected from Gd and Eu) is selected and a fifth auxiliary component composed of from (7) MnO and _Cr 2 _{O 3} A sixth subcomponent composed of at least one oxide and / or a compound that becomes the oxide upon firing, (8) a mixture of CaZrO ₃ , CaO and ZrO ₂ , a compound that becomes CaZrO ₃ upon firing, and firing Containing at least one seventh subcomponent selected from a mixture of a compound that becomes CaO by firing and a compound that becomes ZrO ₂ by firing, and the number of moles of each component, where the mole number of the barium titanate is 100 moles In terms of the number of moles of each of the subcomponents converted to each of the oxides, the first subcomponent: more than 0 and not more than 7 mol, the second subcomponent: 0. 5-12 mol, no. 3 subcomponents: 0.01-0.5 mol, 4th subcomponent: 0-7 mol, 5th subcomponent: 0.5-9 mol, 6th subcomponent: more than 0 and 0.5 mol or less, 7 subcomponents: more than 0 and 5 moles or less, the number A of moles of the second subcomponent, and the total number of moles B of the number of moles of the fifth subcomponent added to the number of moles of the fourth subcomponent A preparation step of preparing a dielectric ceramic composition raw material having a ratio (A / B) of 0.7 or more;
A green sheet for forming a dielectric layer made of the dielectric ceramic composition material and a paste layer for forming an internal electrode layer are fired in an alternately laminated state, and the green sheet becomes a dielectric layer. And a firing step of forming a ceramic chip in which the paste layer is an internal electrode layer;
And a re-oxidation step of re-oxidizing the dielectric layer in the ceramic chip. 5. The multilayer ceramic according to claim 4, wherein the second subcomponent is a composite oxide represented by (Ba, Ca) _x SiO _{2 + x} , and the second subcomponent is 2 to 10 mol. Capacitor manufacturing method. (1) barium titanate and / or a compound or mixture that becomes barium titanate upon firing, and (2) at least one oxide selected from MgO, CaO, BaO and SrO and / or firing to the oxide. Selected from the following: a first subcomponent consisting of a compound comprising: (3) a second subcomponent consisting of an oxide containing 1 mole of Si atoms in 1 mole; and (4) V ₂ O ₅ , MoO ₃ and WO ₃ A third subcomponent composed of at least one oxide and / or a compound that becomes the oxide by firing, and (5) at least one oxide represented by the formula R ¹ ₂ O ₃ and / or by firing. A fourth subcomponent consisting of a compound to be the oxide (where R ¹ is an element selected from Sc, Er, Tm, Yb and Lu), and (6) at least represented by the formula R ² ₂ O ₃ By one oxide and / or firing Compounds that become the oxides (where, ^{R 2} is, Y, Dy, Ho, Tb, element selected from Gd and Eu) is selected and a fifth auxiliary component composed of from (7) MnO and _Cr 2 _{O 3} A sixth subcomponent composed of at least one oxide and / or a compound that becomes the oxide upon firing, (8) a mixture of CaZrO ₃ , CaO and ZrO ₂ , a compound that becomes CaZrO ₃ upon firing, and firing Containing at least one seventh subcomponent selected from a mixture of a compound that becomes CaO by firing and a compound that becomes ZrO ₂ by firing, and the number of moles of each component, where the mole number of the barium titanate is 100 moles In terms of the number of moles of each of the subcomponents converted to each of the oxides, the first subcomponent: more than 0 and not more than 7 mol, the second subcomponent: 0. 5-12 mol, no. 3 subcomponents: 0.01-0.5 mol, 4th subcomponent: 0-7 mol, 5th subcomponent: 0.5-9 mol, 6th subcomponent: more than 0 and 0.5 mol or less, 7 subcomponents: more than 0 and 5 moles or less, the mole number A of the second subcomponent, and the total mole number B of the mole number of the fourth subcomponent plus the mole number of the fifth subcomponent The dielectric ceramic composition raw material, wherein the ratio (A / B) is 0.7 or more.

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