JP6687909B2 - Dielectric composition, dielectric element, electronic component and laminated electronic component - Google Patents

Description

  The present invention particularly relates to a dielectric composition suitable for being used in a high temperature environment such as for vehicle use and an electronic component using the dielectric composition as a dielectric layer.

  A monolithic ceramic capacitor is mounted on many electronic devices because of its high reliability and low cost. Specific electronic devices include information terminals such as mobile phones, home appliances, and automobile electrical components. Among them, the monolithic ceramic capacitors used for in-vehicle use may be required to be guaranteed up to a higher temperature range than the monolithic ceramic capacitors used in home appliances and information terminals, and the function as a capacitor may deteriorate. High reliability that is difficult is required. The characteristics required to prevent the function of the capacitor from deteriorating are that the insulation resistance does not easily deteriorate even if an AC voltage is applied for a long time in a high temperature atmosphere during continuous use. After that, it is important to have a time until it decreases by one digit with respect to the initial insulation resistance value.

  In particular, the surge voltage elimination monolithic ceramic capacitor mounted in an inverter circuit using a power semiconductor such as SiC or GaN, which is considered to be used in a high temperature region of 150 ° C. or higher, has a wide range from −55 ° C. to 200 ° C. High reliability is required at the temperature.

Patent Document 1 discloses a composition formula (1) which is a dielectric ceramic composition showing a sufficient dielectric constant and capable of obtaining stable capacitance temperature characteristics and high resistivity ρ even at a high temperature of about 175 ° C. _{-a) (K 1-x Na} x) (Sr 1-y-z Ba y Ca z) 2 Nb 5 O 15 -a (Ba 1-b Ca b) a tungsten bronze structure compound represented by TiO ₃ with A laminated ceramic capacitor using a dielectric ceramic composition containing a mixed crystal system with a perovskite structure compound as a main component and containing 0.1 to 40 parts by mole of an auxiliary component with respect to 100 parts by weight of the main component. The technology regarding is disclosed.

Patent Document 2, the formula _{(K 1-x Na x)} Sr 2 Nb 5 O 15 ( provided that, 0 ≦ x <0.2) dielectric ceramic comprising tungsten bronze-type composite oxide represented by a principal component In the composition, a dielectric ceramic composition having a high room temperature resistivity by including 0.05 to 20 mol parts of a rare earth element and 0.05 mol to 40 mol parts of Mn, V, Li and the like as auxiliary components. Is disclosed.

In Patent Document 3, by containing a main component containing barium titanate, BaZrO ₃ , an oxide of Mg, a rare earth element, an oxide of Al, and the like and subcomponents of Si, Li, Ge, and B, a high temperature load is obtained. A technique relating to a dielectric ceramic composition which has an excellent life and can be suitably used for medium and high pressure applications is disclosed.

WO2008 / 155945 WO2008 / 102608 JP, 2008-162830, A

  However, in Patent Document 1 described above, although good characteristics are obtained in the high temperature region when the DC voltage is applied for about 1 minute for the measurement time, the AC voltage is continuously applied for a long time. The high temperature load life is insufficient. Further, in Patent Document 2, the insulation property at room temperature is improved by containing various subcomponents, but the high temperature load life in a high temperature region, for example, 250 ° C., is insufficient. Further, in Patent Document 3, the perovskite-type barium titanate-based material has a high high-temperature load life when used at 150 ° C. by containing a subcomponent such as Ge, but the main component is Since it is barium titanate, the relative dielectric constant obtained in the temperature range over 150 ° C. is low and it is difficult to obtain a desired capacitance.

  The present invention has been made in view of the above problems, and provides a dielectric composition having excellent withstand voltage and specific resistance in a high temperature region and having a good high temperature load life, and an electronic component using the same. It is to be.

In order to achieve the above object, the dielectric composition according to the first aspect of the present invention is
The main component is represented by the chemical formula (A _6-x B _x C _{x + 2} D _8-x O ₃₀ , 0 ≦ x ≦ 5),
The component A is at least one element selected from the group consisting of Ba, Ca and Sr,
The B component is at least one element selected from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu,
The C component is at least one element selected from the group consisting of Ti and Zr,
The D component is at least one element selected from the group consisting of Nb and Ta,
The oxide of Ge is contained as a first subcomponent in an amount of 2.50 mol or more and 20.00 mol or less with respect to 100 mol of the main component.

  In the dielectric composition according to the first aspect of the present invention, based on 100 moles of the main component, Mn, Mg, V, W, Mo, Si, Li, B and Al as a second subcomponent are selected. It is preferable to contain at least one oxide selected from 0.10 mol to 20.00 mol.

The dielectric composition according to the second aspect of the present invention is
A dielectric composition comprising a crystal grain and a grain boundary occupying between the crystal grains,
The crystal particles are
It is represented by the chemical formula A _6-x B _x C _{x + 2} D _8-x O ₃₀ (0 ≦ x ≦ 5),
The component A is at least one element selected from the group consisting of Ba, Ca and Sr,
The B component is at least one element selected from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu,
The C component is at least one element selected from the group consisting of Ti and Zr,
The main component is a compound in which the component D is at least one element selected from the group consisting of Nb and Ta,
The dielectric composition contains an oxide of Ge as a first subcomponent and an oxide of V as a second subcomponent,
It is characterized in that the existence ratio of the crystal particles substantially containing Ge is less than 10% with respect to the entire crystal particles.

In the dielectric composition according to the second aspect of the present invention, the average concentration of Ge at the grain boundary is C ₁ , and the average concentration of Ge in the crystal particles substantially containing Ge is C ₂ / C ₁ / C It is preferable that ₂ has a molar ratio of 10 or more.

The dielectric composition according to the third aspect of the present invention is
A dielectric composition comprising a crystal grain and a grain boundary occupying between the crystal grains,
The crystal particles are
It is represented by the chemical formula A _6-x B _x C _{x + 2} D _8-x O ₃₀ (0 ≦ x ≦ 5),
The component A is at least one element selected from the group consisting of Ba, Ca and Sr,
The B component is at least one element selected from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu,
The C component is at least one element selected from the group consisting of Ti and Zr,
The main component is a compound in which the component D is at least one element selected from the group consisting of Nb and Ta,
The dielectric composition contains an oxide of Ge as a first subcomponent and an oxide of V as a second subcomponent,
The average concentration of Ge in the grain boundary is C ₁ , the average concentration of Ge in the crystal grains in which Ge is substantially present is C ₂ , and C ₁ / C ₂ is 10 or more in molar ratio. .

  In the dielectric composition according to the second aspect or the third aspect of the present invention, the content of the oxide of V is more than 1.0 mol and 5.0 mol in terms of V with respect to 100 mol of the main component. The content of the Ge oxide is preferably 10.0 mol or more and 17.5 mol or less in terms of Ge.

Regarding the dielectric composition according to the second aspect or the third aspect of the present invention, the dielectric composition has Mn, Mg, W, Mo, Si, Li, and B as second subcomponents other than V oxide. And at least one oxide selected from the group consisting of Al,
The content of the second subcomponent other than the oxide of V is preferably 0.10 mol or more and 20.00 mol or less in total in terms of each element with respect to 100 mol of the main component.

Regarding the dielectric composition according to the first to third aspects of the present invention,
It is preferable that the main component has a tungsten bronze type crystal structure.

  The dielectric composition having any of the characteristics described above provides a dielectric composition suitable for being used in a high temperature region, having excellent withstand voltage and specific resistance, and having a good high temperature load life. It becomes possible.

  Furthermore, an electronic component having a dielectric layer made of any one of the above-mentioned dielectric compositions is an electronic component for in-vehicle use which is required to be used in a low temperature range of −55 ° C. to about 150 ° C., and It can be used as a snubber capacitor for power devices using SiC or GaN-based semiconductors, which is required up to a higher temperature of about 250 ° C., and a capacitor used for removing noise in the engine room of an automobile.

  A dielectric element according to the present invention comprises any one of the above dielectric compositions.

  An electronic component according to the present invention includes a dielectric layer made of any one of the above dielectric compositions.

  A laminated electronic component according to the present invention has a laminated portion formed by alternately laminating dielectric layers made of any one of the above dielectric compositions and internal electrode layers.

FIG. 1 is a cross-sectional view of a monolithic ceramic capacitor according to an embodiment of the present invention.

(First embodiment)
First, a laminated ceramic capacitor will be described as the laminated electronic component of the present invention. FIG. 1 shows a cross-sectional view of a general monolithic ceramic capacitor.

  The monolithic ceramic capacitor 1 has a capacitor element body 10 in which dielectric layers 2 and internal electrode layers 3 are alternately laminated. At both ends of the capacitor element body 10, a pair of external electrodes 4 is formed which are electrically connected to the internal electrode layers 3 alternately arranged inside the capacitor element body 10. The shape of the capacitor element body 10 is not particularly limited, but is usually a rectangular parallelepiped. The size is not particularly limited, and may be an appropriate size depending on the application.

  The internal electrode layers 3 are laminated so that their ends are alternately exposed on the surfaces of the two opposite end faces of the capacitor element body 10. The pair of external electrodes 4 are formed on both end faces of the capacitor element body 10 and are connected to the exposed ends of the alternately arranged internal electrode layers 3 to form a capacitor circuit.

  The thickness of the dielectric layer 2 is not particularly limited, but is preferably 100 μm or less per layer, and more preferably 30 μm or less. The lower limit of the thickness is not particularly limited, but is, for example, about 0.5 μm. According to the dielectric composition of the present invention, it is possible to form a monolithic ceramic capacitor 1 having a dielectric layer having a high high temperature load life even when the interlayer thickness is 0.5 μm to 30 μm.

  The number of stacked dielectric layers 2 is not particularly limited, but is preferably 20 or more, more preferably 50 or more.

  The conductive material contained in the internal electrode layer 3 is not particularly limited, but Ni, Ni-based alloy, Cu or Cu-based alloy is preferable. Note that various trace components such as P may be contained in Ni, Ni-based alloy, Cu, or Cu-based alloy in an amount of about 0.1 mass% or less. The internal electrode layer 3 may be formed using a commercially available electrode paste. The thickness of the internal electrode layer 3 may be appropriately determined according to the application and the like.

  More preferably, the conductive material contained in the internal electrode layer 3 is Ni or a Ni-based alloy because the constituent material of the dielectric layer 2 has reduction resistance. It is more preferable that this Ni or Ni-based alloy is the main component, and that it also contains one or more kinds of subcomponents for internal electrodes selected from Al, Si, Li, Cr, and Fe.

  By incorporating Ni or Ni-based alloy, which is the main component of the internal electrode layer 3, with one or more kinds of internal electrode subcomponents selected from Al, Si, Li, Cr, and Fe, Ni can be oxygen in the atmosphere. Before reacting with NiO to form NiO, the subcomponent for the internal electrode reacts with oxygen to form an oxide film of the subcomponent for the internal electrode on the surface of Ni. As a result, oxygen in the outside air cannot react with Ni unless it passes through the oxide film of the subcomponent for the internal electrode, so that Ni is less likely to be oxidized. As a result, even when continuously used at a high temperature of 250 ° C., deterioration of continuity and conductivity due to oxidation of the internal electrode layer containing Ni as a main component hardly occurs.

  Although the conductive material contained in the external electrode 4 is not particularly limited, inexpensive Ni, Cu, Au, Ag, Pd having high heat resistance, and alloys thereof can be used in the present invention. The thickness of the external electrode 4 may be appropriately determined according to the application, etc., but is usually preferably about 10 to 50 μm.

  Next, the dielectric composition constituting the dielectric layer according to this embodiment will be described in detail.

The dielectric composition according to this embodiment has the following main components. Principal components are represented by formula _{(A 6-x B x C} x + 2 D 8-x O 30, 0 ≦ x ≦ 5), at least one said component A is selected from the group consisting of Ba, Ca and Sr elements And the B component is at least one element selected from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and the C component Is at least one element selected from the group consisting of Ti and Zr, and the D component is at least one element selected from the group consisting of Nb and Ta. Each component will be described below.

In the present embodiment, the main component represented by the chemical formula _{A 6-x B x C x} + 2 D 8-x O 30, B component Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho , Er, Tm, Yb, and Lu are at least one element selected from the group consisting of. When the main component contains the B component, it is possible to obtain a dielectric composition which is excellent in high temperature load life and withstand voltage while maintaining a high relative dielectric constant.

  Further, x is the substitution amount of the B component, and its range is 0 ≦ x ≦ 5, preferably 0 ≦ x ≦ 3. Therefore, in the present embodiment, the B component in the main component is an arbitrary component. By setting x in the above range, a dielectric composition excellent in high temperature load life can be obtained.

For example, A ₆ C ₂ D ₈ O ₃₀ when x = 0, A ₅ B ₁ C ₃ D ₇ O ₃₀ when x = 1, A ₄ B ₂ C ₄ D ₆ O ₃₀ when x = 2. Alternatively, by using A ₃ B ₃ C ₅ D ₅ O ₃₀ in the case of x = 3 as a main component, a dielectric composition excellent in high temperature load life can be obtained.

In the present embodiment, the main component represented by the chemical formula _{A 6-x B x C x} + 2 D 8-x O 30, A component is at least one element selected from the group consisting of Ba, Ca and Sr, The substitution amount is (6-x). In the present embodiment, x satisfies 0 ≦ x ≦ 5, so that the main component always contains the A component. When the main component contains the substitution amount (6-x) of the A component, a dielectric composition excellent in high temperature load life and withstand voltage can be obtained.

In the present embodiment, the main component represented by the chemical formula _{A 6-x B x C x} + 2 D 8-x O 30, C component is at least one element selected from the group consisting Ti, and Zr, the amount of substitution Is (2 + x). When the main component contains the substitution component (2 + x) of the C component, the band cap is widened, and a dielectric composition having excellent withstand voltage and relative dielectric constant can be obtained.

In the present embodiment, the main component represented by the chemical formula _{A 6-x B x C x} + 2 D 8-x O 30, D component is at least one element selected from the group consisting Nb, from Ta, amount of substitution Is (8-x). Since x satisfies 0 ≦ x ≦ 5 in this embodiment, the main component always includes the D component. When the main component contains the substitution amount (8-x) of the D component, the tungsten bronze type crystal structure is easily maintained, and a dielectric composition excellent in withstand voltage can be obtained.

  The dielectric composition according to the present embodiment contains a Ge oxide as the first subcomponent. The present inventor has found that the dielectric composition containing Ge oxide as the first subcomponent has the effect of suppressing the movement of oxygen defects, which is considered to be the cause of deterioration of the high temperature load life.

  In this embodiment, the content of the Ge oxide as the first subcomponent is 2.50 mol or more and 20.00 mol or less, preferably 5.00 mol or more and 18.00 mol, relative to 100 mol of the main component. It is not more than 1 mol, more preferably not less than 10.00 mol and not more than 17.50 mol. By setting the content of the Ge oxide as the first subcomponent within the above range, the movement of oxygen defects, which is considered to be the cause of deterioration of the high temperature load life, is suppressed, and a sufficient high temperature load life is obtained.

  The dielectric composition according to the present embodiment preferably contains at least one oxide selected from the group consisting of Mn, Mg, V, W, Mo, Si, Li, B and Al as the second subcomponent. The content of the second subcomponent is preferably 0.05 mol or more and 30.00 mol or less, and more preferably 0.10 mol or more and 20.00 mol or less with respect to 100 mol of the main component. By setting the content of the second subcomponent within the above range, the withstand voltage and the specific resistance are further improved. Further, the movement of oxygen defects, which is considered to be the cause of the deterioration of the high temperature load life, is further suppressed, and the high temperature load life is further improved.

  The dielectric composition according to the present embodiment may contain minute impurities and other sub-components as long as the characteristics such as relative permittivity, specific resistance, withstand voltage or high temperature load life are not significantly deteriorated. I don't care. For example, Ba, Ni, Cr, Zn, Cu, Ga or the like may be included in the dielectric composition. The content of the main component with respect to the entire dielectric composition is not particularly limited, but is, for example, 60.0 mol% or more and 97.5 mol% or less with respect to the entire dielectric composition containing the main component. is there.

  Further, in the dielectric composition according to the present embodiment, it is preferable that the main component does not substantially contain highly volatile alkali metal. By not containing an alkali metal, the dielectric composition is less likely to generate lattice defects and conductive electrons are less likely to be generated, and thus has a characteristic of high specific resistance. Furthermore, it is considered that the electrolytic reduction reaction is unlikely to occur under high temperature and high electric field. Therefore, since it is possible to suppress an increase in conduction electrons caused by the reduction reaction, it is considered that a long high temperature load life is exhibited. The phrase “substantially free of alkali metal” refers to, for example, the case where the content of alkali metal is 1.0 at% or less based on all the elements contained in the main component.

  In the dielectric composition according to this embodiment, the main component preferably has a tungsten bronze type crystal structure. Whether or not the main component has a tungsten bronze type crystal structure can be confirmed by an X-ray diffraction (XRD) pattern of the dielectric composition.

In the present embodiment, in the chemical formula A _6-x B _x C _{x + 2} D _8-x O ₃₀ of the main component, when x satisfies 0 ≦ x ≦ 3, the main component is likely to have a tungsten bronze type crystal structure. .

  When the main component has a tungsten bronze type crystal structure, high withstand voltage is easily obtained. The inventors consider this factor as follows. When the main component of the present embodiment has a tungsten bronze type crystal structure, the band gap is widened, so that electrons in the valence band are difficult to excite to the conduction band, and carriers of electrons that are majority carriers involved in conduction It is possible to suppress the concentration. Further, in the electron avalanche, which is a typical breakdown mode of the withstand voltage, it is considered that the carrier concentration of conduction electrons, which is the majority carrier, influences. When the main component has a tungsten bronze type crystal structure, the carrier concentration of the electrons, which are the majority carriers, can be suppressed to a low level, and it is considered that the destruction due to the electron avalanche does not easily occur. Further, when the band gap becomes wide, it is possible to maintain a wide band gap to some extent even when a high electric field strength is applied, and thus it seems that a high withstand voltage is easily obtained even in a high electric field.

  As described above, since the dielectric composition according to the present embodiment exhibits good characteristics in a high temperature region, it is preferably used in a use temperature range (for example, -55 ° C to 250 ° C) of a SiC or GaN-based power device. be able to. Further, it can be suitably used as an electronic component for noise removal in a harsh environment such as an automobile engine room.

  Next, an example of a method for manufacturing the monolithic ceramic capacitor shown in FIG. 1 will be described.

  The monolithic ceramic capacitor 1 of the present embodiment is similar to a conventional monolithic ceramic capacitor in that a green chip is produced by an ordinary printing method or a sheet method using a paste, and after firing this, an external electrode is applied and fired. It is manufactured by The manufacturing method will be specifically described below.

First, the calcined powder of the main component is prepared. As a starting material for the main component, raw material powder of an oxide mainly composed of Sr, Ba, Ca, Ti, Zr, Nb, and Ta, or a mixture thereof can be used. Further, various compounds that become the above-mentioned oxides or complex oxides by firing, such as carbonates, oxalates, nitrates, hydroxides, organometallic compounds, etc., can be appropriately selected and mixed and used. Specifically, SrO may be used as the raw material of Sr, or SrCO ₃ may be used. The average particle diameter of the raw material powder is preferably 1.0 μm or less. After weighing each component so as to have a predetermined composition ratio, wet mixing is performed for a predetermined time using a ball mill or the like. After the obtained mixed powder is dried, it is heat-treated at 1000 ° C. or lower in the atmosphere to obtain a calcined powder as a main component.

Prepare calcined powder of subcomponents. The raw materials for the subcomponents are not particularly limited, and oxides of each component or a mixture thereof can be used as the raw material powder. For example, GeO ₂ powder having an average particle size of 2.0 μm or less can be used as a starting material for the first subcomponent. Further, if necessary, raw material powder of an oxide of Mn, Mg, Co, V, W, Mo, Si, Li, B or a mixture thereof can be used as a starting raw material of the second subcomponent. Further, various compounds that become the above-mentioned oxides or complex oxides by firing, such as carbonates, oxalates, nitrates, hydroxides, organometallic compounds, etc., can be appropriately selected and mixed and used. Specifically, MgO may be used as a raw material of Mg, or MgCO ₃ may be used. After weighing each component so as to have a predetermined composition ratio, wet mixing is performed for a predetermined time using a ball mill or the like. After drying the obtained mixed powder, it is heat-treated in the air at 700 ° C. to 800 ° C. for 1 hour to 5 hours to obtain a calcined powder of a subcomponent. In addition, you may use the mixed powder after heat processing before drying.

  Then, the obtained calcined powder of the main component and the calcined powder of the subcomponent or the mixed powder of the subcomponent are mixed and crushed to obtain a dielectric composition raw material. The dielectric composition raw material is, for example, a mixed powder having an average particle diameter of 0.5 μm to 2.0 μm.

  The dielectric composition raw material obtained above is made into a coating material to prepare a dielectric layer paste. The dielectric layer paste may be an organic paint obtained by kneading a dielectric mixed powder and an organic vehicle, or an aqueous paint.

  The organic vehicle is a binder dissolved in an organic solvent. The binder used for the organic vehicle is not particularly limited and may be appropriately selected from various ordinary binders such as ethyl cellulose and polyvinyl butyral. The organic solvent used is not particularly limited, and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, and acetone according to the method to be used such as the printing method and the sheet method.

  When the dielectric layer paste is a water-based paint, a water-based vehicle in which a water-soluble binder or dispersant is dissolved may be kneaded with the dielectric material. The water-soluble binder used in 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 a conductive material made of the above-mentioned various conductive metals or alloys, or various oxides, organometallic compounds, resinates, etc. which become the above-mentioned conductive material after firing. Prepare.

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

  The content of the organic vehicle in each paste described above is not particularly limited and may be a normal content, for example, the binder is about 1% by mass to 5% by mass, and the solvent is about 10% by mass to 50% by mass. In addition, each paste may contain additives selected from various dispersants, plasticizers, dielectric materials, insulating materials, and the like, if necessary. The total content of these is preferably 10% by mass or less.

  When the printing method is used, the dielectric layer paste and the internal electrode layer paste are printed and laminated 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, an internal electrode layer paste is printed thereon, and these are laminated to form a green chip.

Before firing, the green chip is subjected to binder removal processing. As the binder removal treatment condition, the temperature rising rate is preferably 5 ° C./hour to 300 ° C./hour, the holding temperature is preferably 180 ° C. to 500 ° C., and the temperature holding time is preferably 0.5 hour to 24 hours. The atmosphere for the binder removal processing is air or a reducing atmosphere. In the binder removal treatment, for example, a wetter or the like may be used to humidify the N ₂ gas, the mixed gas, or the like. In this case, the water temperature is preferably about 5 ° C to 75 ° C.

  The holding temperature during firing is preferably 1100 ° C to 1400 ° C. If the holding temperature is less than the above range, the densification becomes insufficient, and if it exceeds the above range, the electrode breaks due to abnormal sintering of the internal electrode layer, and the capacity change rate deteriorates due to the diffusion of the internal electrode layer constituent material. It will be easier. On the other hand, if it exceeds the above range, the crystal grains may be coarsened and the high temperature load life may be shortened.

  The temperature rising rate is preferably 200 ° C./hour to 5000 ° C./hour. In order to control the particle size distribution after sintering within the range of 0.5 μm to 5.0 μm and to suppress the volume diffusion of crystal particles, the temperature holding time is preferably 0.5 hours to 2. The cooling rate is preferably 0 ° C./hour to 500 ° C./hour for 0 hours.

Further, as the atmosphere for firing, it is preferable to use a mixed gas of humidified N ₂ and H ₂ and fire at an oxygen partial pressure of 10 ⁻² to 10 ⁻⁶ Pa. However, if firing is performed in a state where the oxygen partial pressure is high, Ni is oxidized in the case of the internal electrode layer containing Ni, and the conductivity as an electrode is reduced. In this case, a conductive material containing Ni as a main component, which is a more preferable form of the present embodiment, should contain one or more kinds of internal electrode subcomponents selected from Al, Si, Li, Cr, and Fe. Therefore, the oxidation resistance of Ni is improved, and it becomes possible to secure the conductivity as the internal electrode layer even in an atmosphere with a high oxygen partial pressure.

  After firing, the obtained capacitor element body is annealed if necessary. The annealing condition may be a known condition. For example, it is preferable that the oxygen partial pressure during the annealing treatment be higher than the oxygen partial pressure during the firing, and the holding temperature be 1000 ° C. or lower.

  Further, although the manufacturing method in which the binder removal treatment, the firing and the annealing treatment are independently performed is described above, they may be continuously performed.

  The capacitor element body obtained as described above is subjected to end face polishing by, for example, barrel polishing or sandblasting, and an external electrode paste is applied and baked to form the external electrode 4. Then, if necessary, a coating layer is formed on the surface of the external electrode 4 by plating or the like.

(Second embodiment)
The second embodiment of the present invention will be described below. Items not described below are the same as those in the first embodiment.

The dielectric composition according to the present embodiment is a dielectric composition including crystal grains and grain boundaries that occupy between the crystal grains. The grain boundary includes a two-grain grain boundary phase existing between two crystal grains and a grain boundary multiple point existing between three or more crystal grains. Then, consisting mainly composed of the crystal grains is represented by the formula _{(A 6-x B x C} x + 2 D 8-x O 30, 0 ≦ x ≦ 5). Further, some particles composed of precipitates other than the main component may be present as long as the object of the present invention is not impaired.

  In the dielectric composition according to the present embodiment, Ge exists at a high concentration in the grain boundary. As a result, the ratio of the number of crystal particles substantially not containing Ge to the total crystal particles is 90% or more. That is, the number ratio of the crystal particles substantially containing Ge is less than 10%. In addition, that the crystal grains do not substantially contain Ge means that the area of the region where Ge exists is 10% or less in the cross section of the crystal grains. That is, in the dielectric composition according to the present embodiment, Ge does not substantially exist in 90% or more of crystal grains, and most of Ge exists in grain boundaries.

  Further, regarding whether or not the crystal particles substantially contain Ge, FE-TEM-EDX (transmission electron microscope-energy dispersion) is applied to the cross section of the crystal particles, that is, the cross section of the dielectric composition including the crystal particles. Type X-ray analysis method). The conditions of EDX in this embodiment are a probe diameter of 1 nm and an acceleration voltage of 200 kV. The region in which Ge is detected under the conditions is a region in which Ge exists regardless of the amount of Ge detected. Moreover, in calculating the number ratio of the crystal grains in which Ge is substantially absent, the observation range is set to a range in which the cross section of at least 100 crystal grains can be observed.

Further, assuming that the average concentration of Ge at the grain boundary is C ₁ and the average concentration of Ge in the crystal particles substantially containing Ge is C ₂ , the molar ratio of C ₁ / C ₂ is preferably 10 or more, and 20 or more. Is more preferable. When C ₁ / C ₂ is 10 or more, the effect of suppressing the movement of oxygen defects, which is considered to be the cause of deterioration of the high temperature load life, can be obtained by the presence of Ge present at a high concentration at the grain boundary. Then, it becomes easy to provide a dielectric composition having a high high temperature load life.

  The dielectric composition according to the present embodiment contains at least a Ge oxide as a first subcomponent and a V oxide as a second subcomponent. By including the oxide of V at the same time as the oxide of Ge, it becomes possible to suppress the solid solution of Ge in the crystal particles.

  In the present embodiment, the content of the Ge oxide as the first subcomponent is preferably 10.0 mol or more and 17.5 mol or less in terms of Ge with respect to 100 mol of the main component. By setting the content of the Ge oxide as the first subcomponent within the above range, the movement of oxygen defects, which is considered to be the cause of the deterioration of the high temperature load life, is suppressed, and a more excellent high temperature load life is easily obtained. In addition, the content of the oxide of V as the second subcomponent is preferably more than 1.00 mol and 5.0 mol or less in terms of V with respect to 100 mol of the main component. This makes it possible to increase the proportion of crystal grains that do not substantially contain Ge to 95% and increase the average concentration of Ge at the grain boundaries, so that it becomes easier to obtain a better high temperature load life.

  The dielectric composition according to the present embodiment contains at least one oxide selected from the group consisting of Mn, Mg, W, Mo, Si, Li, B and Al as the second subcomponent other than the oxide of V. It is preferable. Further, the content of the second subcomponent other than the oxide of V is preferably 0.10 mol or more and 20.00 mol or less in total in terms of each element with respect to 100 mol of the main component. By setting the content of the second subcomponent other than the oxide of V in the above range, the withstand voltage and the specific resistance are further improved. Further, the movement of oxygen defects, which is considered to be the cause of the deterioration of the high temperature load life, is further suppressed, and the high temperature load life is further improved.

(Third Embodiment)
The third embodiment of the present invention will be described below. Items not described below are the same as those in the second embodiment.

In the dielectric composition according to the present embodiment, the average concentration of Ge at the grain boundaries is C ₁ , and the average concentration of Ge in the crystal grains substantially containing Ge is C ₂ , and the molar ratio of C ₁ / C ₂ is 10. That is all. Further, it is more preferably 20 or more. When C ₁ / C ₂ is 10 or more, the effect of suppressing the movement of oxygen defects, which is considered to be the cause of deterioration of the high temperature load life, can be obtained by the presence of Ge present at a high concentration at the grain boundary. And the dielectric composition which has a high high temperature load life can be provided.

  Further, in the dielectric composition according to the present embodiment, it is preferable that the number ratio of the crystal particles substantially not containing Ge to the entire crystal particles is 90% or more.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

  Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention, but the present invention is not limited to these examples. The samples marked with * in Tables 1 to 4 are outside the scope of the present invention.

(Example 1)
As a starting material of the main component, SrCO ₃ , BaCO ₃ , CaCO ₃ , TiO ₂ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , Y ₂ O ₃ , La ₂ O ₃ having an average particle size of 1.0 μm or less, _{Pr 2 O 3, Nd 2 O} 3, Sm 2 O 3, Eu 2 O 3, Gd 2 O 3, Tb 2 O 3, Dy 2 O 3, Ho 2 O 3, Er 2 O 3, Tm 2 O 3, Powders of Yb ₂ O ₃ and Lu ₂ O ₃ were prepared. These were weighed so as to have the main component composition of each sample number in Table 1, and wet-mixed for 24 hours by a ball mill using ethanol as a dispersion medium. The obtained mixture was dried and heat-treated in the atmosphere at a holding temperature of 900 ° C. for a holding time of 2 hours to obtain a calcined powder as a main component.

GeO ₂ powder as a starting material for the first subcomponent, and MnO, MgO, V ₂ O ₅ , WO ₃ , MoO ₃ , SiO ₂ , Li ₂ CO ₃ , B ₂ O ₃ , and Al ₂ as starting materials for the second subcomponent. Each powder of O ₃ was prepared. These were weighed so as to have the compounding ratio shown in Table 1, and wet-mixed for 24 hours by a ball mill using ethanol as a dispersion medium. The obtained mixture was dried and heat-treated in the atmosphere at a holding temperature of 800 ° C. for a holding time of 2 hours to obtain a calcined powder of a subcomponent.

  The main component calcined powder obtained by the above method and the sub-component calcined powder were mixed and crushed to obtain a dielectric composition raw material. To 1000 g of this dielectric composition raw material, 700 g of a solvent prepared by mixing a toluene + ethanol solution, a plasticizer and a dispersant at 90: 6: 4 was added, and a basket mill, which is a well-known dispersion method, was used. And dispersed for 2 hours to prepare a dielectric layer paste. The viscosity of each of these pastes was adjusted to about 200 cps.

As raw materials for the internal electrode layers, Ni having an average particle size of 0.2 μm, Al having an average particle size of 0.1 μm or less, and Si oxide having an average particle size of 0.1 μm or less are prepared, and Al is contained. The total amount and the content of Si (content obtained by converting the content of the oxide of Si into the content of Si) were weighed so as to be 5% by mass with respect to Ni. Then, heat treatment was performed in a mixed gas of N ₂ and H ₂ that was humidified at 1200 ° C. or higher, and the mixture was crushed using a ball mill or the like to prepare several kinds of raw material powders having an average particle diameter of 0.20 μm.

  100 parts by mass of the raw material powder, 30 parts by mass of an organic vehicle (8 parts by mass of ethyl cellulose resin dissolved in 92 parts by mass of butyl carbitol), and 8 parts by mass of butyl carbitol were kneaded with a three-roll to form a paste. Thus, an internal electrode layer paste was obtained.

  Then, using the prepared dielectric layer paste, a green sheet was formed on the PET film so that the thickness after drying was 12 μm. Then, the internal electrode layer paste was printed thereon with a predetermined pattern by using an internal electrode layer paste, and then the sheet was peeled from the PET film to produce a green sheet having the internal electrode layer. Next, a plurality of green sheets each having an internal electrode layer were laminated and pressure-bonded to form a green laminated body, and the green laminated body was cut into a predetermined size to obtain a green chip.

  Next, the obtained green chip was subjected to binder removal treatment, firing, and annealing treatment to obtain a laminated ceramic fired body. The conditions for binder removal processing, firing and annealing are as follows. A wetter was used to humidify each atmosphere gas.

(Binder removal processing)
Temperature rising rate: 100 ° C / hour Holding temperature: 400 ° C
Temperature holding time: 8.0 hours Atmosphere gas: Mixed gas of humidified N ₂ and H ₂

(Baking)
Temperature rising rate: 500 ° C / hour Holding temperature: 1200 ° C to 1350 ° C
Temperature holding time: 2.0 hours Cooling rate: 100 ° C./hour Atmosphere gas: Moistened mixed gas of N ₂ and H ₂ Oxygen partial pressure: 10 ⁻⁵ to 10 ⁻⁹ Pa

(Annealing treatment)
Holding temperature: 800 ℃ ~ 1000 ℃
Temperature holding time: 2.0 hours temperature rise, temperature decrease rate: 200 ° C./hour Atmosphere gas: humidified N ₂ gas

  The dielectric layer (dielectric composition) of each of the obtained laminated ceramic sintered bodies was subjected to composition analysis of each sample by ICP emission spectroscopy, and as a result, the dielectric composition raw materials shown in Table 1 were obtained. It was confirmed that the value was almost the same as the composition.

  Further, it was confirmed from the X-ray diffraction pattern that the dielectric layer (dielectric composition) of each obtained multilayer ceramic sintered body had a tungsten bronze type crystal structure. It was evaluated as ◯ when it had a tungsten bronze type crystal structure, and as x when it did not have it. The results are shown in Table 2. In Table 2, the tungsten bronze type is referred to as the TB type.

  After polishing the end faces of the obtained monolithic ceramic sintered body by sandblasting, an In-Ga eutectic alloy was applied as an external electrode, and sample No. 1 to Sample No. 75 multilayer ceramic capacitor samples were obtained. The size of each of the obtained multilayer ceramic capacitor samples was 3.2 mm × 1.6 mm × 1.2 mm, the thickness of the dielectric layer was 10 μm, the thickness of the internal electrode layer was 2 μm, and the dielectric layer sandwiched between the internal electrode layers. The number of layers was 50.

  The obtained sample No. 1 to Sample No. The 75 laminated ceramic capacitor samples were measured for relative permittivity (εs), specific resistance, high temperature load life, and withstand voltage by the methods shown below. The results are shown in Table 2.

[Specific permittivity (εs)]
A capacitance L was measured by inputting a signal having a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms to a multilayer ceramic capacitor at 25 ° C. with a digital LCR meter (4284A manufactured by YHP). Then, the relative permittivity εs (no unit) was calculated based on the thickness of the dielectric layer, the effective electrode area, and the capacitance C obtained as a result of the measurement. The higher the relative permittivity, the better, and it was judged that 250 or more was good.

[Specific resistance]
The insulation resistance of the multilayer ceramic capacitor sample was measured at 225 ° C. with a digital resistance meter (R8340 manufactured by ADVANTEST Co., Ltd.) under the conditions of a measurement voltage of 30 V and a measurement time of 60 seconds. The specific resistance value was calculated from the electrode area of the capacitor sample and the thickness of the dielectric layer. The higher the specific resistance is, the more preferable it is. 1.00 × 10 ¹² Ωcm or more, more preferably 6.00 × 10 ¹² Ωcm or more is judged to be good. If the specific resistance is low, the capacitor has a large leakage current, which causes a malfunction in an electric circuit.

[High temperature load life]
In the high temperature load life test, with respect to 200 samples of each sample number, a DC voltage was applied at a temperature of 250 ° C. so as to be 40 V / μm with respect to the thickness of the dielectric layer, and a change in insulation resistance with time was measured. The time until the insulation resistance deteriorates by one digit was determined as the failure time, and the mean failure time (MTTF) of 50% was obtained from the Weibull analysis of the failure time. In the present invention, the mean time to failure (MTTF) is defined as the high temperature load life. It is judged that the high temperature load life is preferably long, 500 hours or more is more preferable, 550 hours or more is more preferable, and 1200 hours or more is more preferable.

[Withstand voltage]
An AC voltage was applied to the multilayer ceramic capacitor sample at a temperature rising rate of 100 V / sec at 250 ° C., and the AC voltage when the leakage current exceeded 10 mA was taken as the AC withstand voltage. The higher the AC withstand voltage is, the better, and it is judged that 75.0 V / μm or more is good. More preferably, it is 100.0 V / μm or more.

From the results in Table 2, x satisfies 0 ≦ x ≦ 5 in the main component represented by the chemical formula A _6-x B _x C _{x + 2} D _8-x O ₃₀ and further, with respect to 100 mol of the main component, Sample No. containing 2.50 mol or more and 20.00 mol or less of Ge oxide as a component. 1, 2, 5-10, 12-25 and 27-75 are excellent in relative permittivity at 25 ° C, specific resistance at 225 ° C, high temperature load life at 250 ° C, and AC withstand voltage at 250 ° C. It was confirmed.

  Among them, sample No. having a tungsten bronze type crystal structure as a main component. It was confirmed that Nos. 1, 2, 5-10, 12-23 and 27-75 were excellent in high temperature load life at 250 ° C and AC withstand voltage at 250 ° C.

  In addition, Sample No. containing at least one oxide selected from the group consisting of Mn, Mg, V, W, Mo, Si, Li, B, and Al as the second subcomponent in an amount of 0.10 mol or more and 20.00 mol or less. 51-69 and 72 were confirmed to have excellent AC withstand voltage at 250 ° C.

(Example 2)
In Example 2, sample No. 1 was prepared in the same manner as in Example 1 except that the starting materials were weighed so as to have the compounding ratio shown in Table 3. 101-Sample No. A laminated ceramic capacitor of 175 was obtained.

    The obtained sample No. For the multilayer ceramic capacitor samples 101 to 175, the presence or absence of a tungsten bronze type crystal structure was confirmed by the same method as in Example 1, and the relative dielectric constant, the specific resistance, the high temperature load life, and the withstand voltage were measured.

Furthermore, the multilayer ceramic capacitor sample was cut and the cross section of the dielectric composition was observed. Specifically, whether or not Ge is substantially present in each crystal grain in a visual field of a size in which at least 100 crystal grains are present in the visual field, and the proportion of the crystal grains in which Ge is substantially absent Was confirmed using FE-TEM-EDX. That is, the existence ratio of the crystal particles in which the area ratio of the region where Ge is present is less than 10% was specified. Specifically, FE-TEM-EDX was used to specify the area of the region where Ge was present in each crystal particle, and the ratio of the crystal particle having the area of 10% or less to the whole crystal particle was specified. The EDX conditions were a probe diameter of 1 nm and an acceleration voltage of 200 kV. Further, the average concentration of Ge at the grain boundaries in the visual field was measured. Specifically, 20 measurement points were arbitrarily selected from the grain boundaries in the visual field to measure the Ge concentration, and averaged to obtain C ₁ . In addition, the concentration of Ge in the crystal particles in which each Ge is substantially present was measured and averaged to obtain C ₂ . Then, C ₁ / C ₂ in each sample was calculated. The results are shown in Table 4. In Table 4, the tungsten bronze type is referred to as the TB type.

From the results of Table 3 and Table 4, the main component, the oxide of Ge (first subcomponent) and the oxide of V (second subcomponent), which consist of crystal grains composed of the main component and grain boundaries occupying between the crystal grains, are obtained. ), The relative dielectric constant at 25 ° C., the specific resistance at 225 ° C., the high temperature load life at 250 ° C. and It was confirmed that the AC withstand voltage at ℃ was excellent. In addition, it is composed of crystal grains composed of a main component and a grain boundary occupying between the crystal grains, contains a main component, an oxide of Ge (first subcomponent) and an oxide of V (second subcomponent), and C ₁ It has been confirmed that even when / C ₂ is 10 or more in molar ratio, the dielectric constant at 25 ° C., the specific resistance at 225 ° C., the high temperature load life at 250 ° C., and the AC withstanding voltage at 250 ° C. are excellent. It was

    Further, the content of the oxide of V is more than 1.0 mol and 5.0 mol or less in terms of V, and the content of the oxide of Ge is 10.0 mol or more and 17.5 mol or less. It was confirmed that the capacitor sample was particularly excellent in high temperature load life at 250 ° C.

  Further, in the case of a multilayer ceramic capacitor sample containing a total of 0.10 mol or more and 20.00 mol or less of the second subcomponents other than the oxide of V in terms of each element, the resistivity at 225 ° C. and the AC withstand voltage at 250 ° C. It was confirmed to be excellent.

  The embodiments and examples disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above-described embodiments and examples but by the scope of the claims, and is intended to include meanings equivalent to the scope of the claims and all modifications and variations within the scope.

  The dielectric composition of the present invention has a high relative permittivity, and particularly has a long specific resistance in a high temperature region, a withstand voltage and a high temperature load life, and thus can be applied as an in-vehicle electronic component in an environment close to an engine room. It can also be applied as an electronic component mounted near a power device using a SiC or GaN-based semiconductor.

1 Multilayer Ceramic Capacitor 2 Dielectric Layer 3 Internal Electrode Layer 4 External Electrode 10 Capacitor Element Body

Claims (10)

The main component is represented by the chemical formula (A _6-x B _x C _{x + 2} D _8-x O ₃₀ , 0 ≦ x ≦ 5),
The component A is at least one element selected from the group consisting of Ba, Ca and Sr,
The B component is at least one element selected from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu,
The C component is at least one element selected from the group consisting of Ti and Zr,
The D component is at least one element selected from the group consisting of Nb and Ta,
The main component with respect to 100 moles, the oxide of Ge seen contains 2.50 mol to 20.00 mol as a first subcomponent,
A dielectric composition wherein the main component has a tungsten bronze type crystal structure .   20. 0.10 mol or more of at least one oxide selected from the group consisting of Mn, Mg, V, W, Mo, Si, Li, B and Al as the second subcomponent with respect to 100 mol of the main component. The dielectric composition according to claim 1, comprising not more than 00 mol. A dielectric composition comprising a crystal grain and a grain boundary occupying between the crystal grains,
The crystal particles are
A compound represented by the chemical formula A _6-x B _x C _{x + 2} D _8-x O ₃₀ (0 ≦ x ≦ 5) as a main component,
The component A is at least one element selected from the group consisting of Ba, Ca and Sr,
The B component is at least one element selected from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu,
The C component is at least one element selected from the group consisting of Ti and Zr,
The D component is at least one element selected from the group consisting of Nb and Ta,
The dielectric composition contains an oxide of Ge as a first subcomponent and an oxide of V as a second subcomponent,
Ri existing ratio is less than 10% der of the crystal grains substantially comprising Ge for entire crystal grains,
The dielectric composition characterized Rukoto said main component having a crystal structure of the tungsten bronze type. The average concentration of Ge in the grain boundary is C ₁ , and the average concentration of Ge in the crystal particles substantially containing Ge is C ₂ , and C ₁ / C ₂ is 10 or more in molar ratio. Dielectric composition. A dielectric composition comprising a crystal grain and a grain boundary occupying between the crystal grains,
The crystal particles are
A compound represented by the chemical formula A _6-x B _x C _{x + 2} D _8-x O ₃₀ (0 ≦ x ≦ 5) as a main component,
The component A is at least one element selected from the group consisting of Ba, Ca and Sr,
The B component is at least one element selected from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu,
The C component is at least one element selected from the group consisting of Ti and Zr,
The D component is at least one element selected from the group consisting of Nb and Ta,
The dielectric composition contains an oxide of Ge as a first subcomponent and an oxide of V as a second subcomponent,
The average concentration of Ge in the crystal grains the average concentration of Ge in the grain boundary _C 1, Ge substantially present as _{C 2,} Ri der 10 or more C 1 / _{C 2} is molar ratio,
The dielectric composition characterized Rukoto said main component having a crystal structure of the tungsten bronze type.   The content of the oxide of V is more than 1.0 mol and 5.0 mol or less in terms of V, and the content of the oxide of Ge is 10.0 mol in terms of Ge with respect to 100 mol of the main component. The dielectric composition according to any one of claims 3 to 5, which is not less than 17.5 mol and not more than 1.75 mol. The dielectric composition contains at least one oxide selected from the group consisting of Mn, Mg, W, Mo, Si, Li, B and Al as a second accessory component other than the oxide of V,
The content of the second subcomponent other than the oxide of V is 0.10 mol or more and 20.00 mol or less in total in terms of each element with respect to 100 mol of the main component. The dielectric composition described. Dielectric device comprising a dielectric composition according to any of the claims 1-7. Electronic component comprising a dielectric layer comprising a dielectric composition according to any of the claims 1-7. Multilayer electronic component having the claims 1-7 or dielectric stacked portion formed by stacking comprising the composition of dielectric layers and internal electrode layers alternately according to the.

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