Dielectric ceramic composition, method for manufacturing a dielectric ceramic composition, and multilayer ceramic capacitor

Abstract

To provide a dielectric ceramic composition having excellent temperature properties in a wide temperature range from room temperature to over 200°C and low DC bias dependence, a method of manufacturing a dielectric ceramic composition, and a multilayer ceramic capacitor.SOLUTION: A dielectric ceramic composition comprises: a component including a base material represented by Ba(Ti(1-2x)RxWx)O3, wherein R is Mn and / or Mg, and x satisfies 0.06≤x≤0.10. There are also provided a method of manufacturing the dielectric ceramic composition, and a multilayer ceramic capacitor including the same.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] This invention relates to a dielectric ceramic composition, a method for producing a dielectric ceramic composition, and a multilayer ceramic capacitor. [Background technology]

[0002] As automobiles become increasingly electronically controlled, the demands on the performance and reliability of the electronic components used are rising. For example, electronic components used in the power modules of electric vehicles require reliability under high-temperature conditions. In the case of ceramic capacitors, capacitance characteristics (X8R characteristics) under temperature changes are required. In recent years, the development of power semiconductors with high operating temperatures has progressed in electric vehicles and other applications, and there is a growing demand for multilayer ceramic capacitors that have high reliability at high temperatures of 200°C or higher. Furthermore, dielectric ceramic compositions with low DC bias dependence are required for use at high voltages.

[0003] Various barium titanate-based dielectric ceramic compositions have been conventionally known (for example, Patent Documents 1 to 6). However, no dielectric ceramic composition is known that exhibits excellent temperature characteristics even at high temperatures above 200°C and has low DC bias dependence. [Prior art document] [Patent] [Patent Document 1] Japanese Unexamined Patent Publication No. 2018-203590 [Patent Document 2] Japanese Unexamined Patent Publication No. 2011-11918 [Patent Document 3] International Publication No. 2004 / 067473 [Patent Document 4] Patent No. 6571048 [Patent Document 5] Patent No. 4782552 [Patent Document 6] Patent No. 5883217 [Overview of the project] [Problems that the invention aims to solve]

[0004] Provided are a dielectric ceramic composition, a method for manufacturing a dielectric ceramic composition, and a multilayer ceramic capacitor, which have excellent temperature characteristics in a wide temperature range from room temperature to 200°C or higher and low DC bias dependence.

Means for Solving the Problems

[0005] In order to solve the above problems, in a first aspect of the present invention, a dielectric ceramic composition containing a component derived from a base material represented by Ba(Ti (1-2x) R x W x )O3 is provided. Here, R is Mn and / or Mg. x satisfies 0.06 ≦ x ≦ 0.10.

[0006] In a second aspect of the present invention, a dielectric ceramic composition containing a component derived from a base material represented by Ba(Ti (1-2x) R x W x )O3 is provided. Here, R is Mn and / or Mg. x satisfies 0.06 ≦ x ≦ 0.10. The dielectric ceramic composition is obtained by firing at least a base material and an additive. The base material is obtained by subjecting BaCO3, TiO2, and RO to a first calcination by a solid-phase method, then making it a mixture with WO3, and further subjecting it to a second calcination to obtain a calcined powder as the base material.

[0007] In a third aspect of the present invention, a dielectric ceramic composition containing a component derived from a base material represented by Ba(Ti (1-2x) R x W x )O3 is provided. Here, R is Mn and / or Mg. x satisfies 0.06 ≦ x ≦ 0.10. The dielectric ceramic composition is obtained by firing at least a base material and an additive. The base material is obtained by subjecting TiO2, RO, and WO3 to a first calcination by a solid-phase method, then making it a mixture with BaCO3, and further subjecting it to a second calcination to obtain a calcined powder as the base material.

[0008] In a fourth aspect of the present invention, Ba(Ti (1-2x) R x W x)To provide a dielectric porcelain composition containing dielectric grains derived from a base material represented by Ba(Ti

[0009] In a fifth aspect of the present invention, (1-2x) R x W x )O3. Here, R is Mn and / or Mg. x satisfies 0.06 ≦ x ≦ 0.10. The dielectric grains do not have a core-shell structure.

[0010] In a sixth aspect of the present invention, a method for manufacturing a dielectric porcelain composition is provided. The manufacturing method includes a first calcination step of calcining BaCO3, TiO2, and RO by a solid-phase method to form a first calcined powder, a second calcination step of further calcining a mixture of the first calcined body and WO3 to form a base material of the dielectric porcelain composition, and a main firing step of main firing the base material and an additive to obtain the dielectric porcelain composition. The base material is Ba(Ti (1-2x) R x W x )O3. R is Mn and / or Mg. x satisfies 0.06 ≦ x ≦ 0.10.

[0011] In a seventh aspect of the present invention, a method for manufacturing a dielectric porcelain composition is provided. The manufacturing method includes a first calcination step of calcining TiO2, RO, and WO3 by a solid-phase method to form a first calcined powder, a second calcination step of further calcining a mixture of the first calcined body and BaCO3 to form a base material of the dielectric porcelain composition, and a main firing step of main firing the base material and an additive to obtain the dielectric porcelain composition. The base material is Ba(Ti (1-2x) R x W x )O3. R is Mn and / or Mg. x satisfies 0.06 ≦ x ≦ 0.10.

[0012] Note that the above summary of the invention does not list all the features of the present invention. Also, sub-combinations of these feature groups can also be inventions.

Brief Description of the Drawings

[0013] [Figure 1A] It is a graph showing the XRD (X-Ray Diffraction) analysis results in the dielectric ceramic compositions according to Example A1 and Example A2. [Figure 1B] It is a graph showing the XRD (X-Ray Diffraction) analysis results in the dielectric ceramic compositions according to Example A3 and Example A4. [Figure 1C] It is a graph showing the XRD (X-Ray Diffraction) analysis results in the dielectric ceramic compositions according to Example B1 and Example B2. [Figure 1D] It is a graph showing the XRD (X-Ray Diffraction) analysis results in the dielectric ceramic compositions according to Comparative Example 1 and Comparative Example 2. [Figure 1E] It is a graph showing the XRD (X-Ray Diffraction) analysis results in the dielectric ceramic compositions according to Comparative Example A5 and Comparative Example A6. [Figure 1F] It is a graph showing the XRD (X-Ray Diffraction) analysis results in the dielectric ceramic compositions according to Comparative Example B3 and Comparative Example B4. [Figure 2A] It is a graph showing the capacitance temperature change rate in the dielectric ceramic compositions according to the examples and comparative examples. [Figure 2B] It is a graph showing the capacitance temperature change rate in the dielectric ceramic compositions according to the examples and comparative examples. [Figure 3A] It is a graph showing the DC bias attenuation rate in the dielectric ceramic compositions according to the examples and comparative examples. [Figure 3B] It is a graph showing the DC bias attenuation rate in the dielectric ceramic compositions according to the examples and comparative examples.

Modes for Carrying Out the Invention

[0014] The present invention will be described below through embodiments of the invention, but these embodiments are not intended to limit the invention as defined in the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0015] [1] Composition of dielectric ceramic composition: The composition of the dielectric porcelain composition according to this embodiment will be described.

[0016] In this embodiment, the dielectric ceramic composition is Ba(Ti (1-2x) R x W x It contains components derived from the base material represented by O3. Here, "contains components derived from the base material" means the base material itself, or components obtained by modifying the base material through post-processing such as sintering. For example, a dielectric ceramic composition may contain derivative grains obtained by sintering the base material.

[0017] As an example, the base material may be a barium titanate-based compound having a perovskite structure. In the base material, some of the Ti sites of the barium titanate are substituted with R and W. R is Mn and / or Mg. R may contain both Mn and Mg.

[0018] x may satisfy 0.05 ≤ x ≤ 0.12. Preferably, it may satisfy 0.06 ≤ x ≤ 0.10. More preferably, it may satisfy 0.07 ≤ x ≤ 0.09. As an example, x may be 0.06, 0.07, 0.08, 0.09, and 0.10.

[0019] Dielectric ceramic composition is Ba(Ti (1-2x) R x W x Whether or not a dielectric ceramic composition contains components derived from the base material represented by O3 can be determined by analyzing the dielectric grains derived from the base material. Specifically, dielectric grains derived from the base material can be confirmed by STEM / WDS analysis or STEM / EELS analysis.

[0020] The dielectric ceramic composition may be a dielectric ceramic composition obtained by firing a base material and additives. The base material may be a calcined powder obtained by first calcining BaCO3, TiO2, and RO using a solid-phase method, then mixing it with WO3, and further calcining it a second time. Alternatively, the base material may be a calcined powder obtained by first calcining TiO2, RO, and WO3 using a solid-phase method, then mixing it with BaCO3, and further calcining it a second time.

[0021] Dielectric ceramic composition is Ba(Ti (1-2x) R x W x It may contain dielectric grains derived from a base material represented by O3, where R may be Mn and / or Mg, and x may satisfy 0.06 ≤ x ≤ 0.10. The dielectric grains may not have a core-shell structure.

[0022] The absence of a core-shell structure means that the dielectric grain does not consist of a core and shell portion made up of parts with different compositions. For example, if it has a homogeneous structure as described later, it can be said that it does not have a core-shell structure. The presence or absence of a core-shell structure can be confirmed, for example, by observing the dielectric grain using STEM or SEM.

[0023] Furthermore, the dielectric grain may have a homogeneous structure. Here, a homogeneous structure means that the elemental concentrations of the components contained in the dielectric grain are the same throughout the dielectric grain, or that the variation in the concentrations of the components within the dielectric grain is substantially negligible.

[0024] For example, in dielectric grains making up 50% or more of a dielectric ceramic composition, the standard deviation (σ) of the Ti concentration in the dielectric grains may be 5% or less, 3% or less, and more preferably 1% or less. The Ti concentration in the dielectric grains can be confirmed, for example, by STEM / WDS analysis or STEM / EELS analysis of the dielectric grains.

[0025] The dielectric ceramic composition may contain RO and WO3 in the base material in an amount of 5.0% by weight or more and 11.0% by weight or less relative to the total base material.

[0026] The auxiliary components used in the manufacture of dielectric ceramic compositions are not particularly limited. Dielectric ceramic compositions may contain barium compounds, manganese compounds, vanadium compounds, magnesium compounds, calcium compounds, silicon compounds, etc., as auxiliary components. For example, barium compounds may be barium oxide (BaO), barium carbonate (BaCO3), or barium chloride (BaCl2). Manganese compounds may be manganese oxide (MnO2, Mn2O3, Mn3O4), etc. Vanadium compounds may be vanadium pentoxide, etc. Magnesium compounds may be magnesium oxide (MgO), etc. Calcium compounds may be calcium carbonate (CaCO3), etc. Silicon compounds may be silicon dioxide (SiO2), etc.

[0027] Examples of the composition ranges for these minor components are described below. For example, per 100 mol of base material, the barium compound (total amount if there are two or more types) may be used in an amount of 0.1 mol to 4.0 mol in terms of Ba. Per 100 mol of base material, the manganese compound (total amount if there are two or more types) may be used in an amount of 0.01 mol to 0.5 mol in terms of Mn. Per 100 mol of base material, the magnesium compound (total amount if there are two or more types) may be used in an amount of 0.1 mol to 2.0 mol in terms of Mg. Per 100 mol of base material, the vanadium compound (total amount if there are two or more types) may be used in an amount of 0.01 mol to 3.0 mol in terms of V.

[0028] [2] Form and properties of dielectric ceramic compositions: The form of the dielectric ceramic composition in this embodiment is not particularly limited. The dielectric ceramic composition can take the form of a plate, a sphere, a pellet, or the like. It can also take a composite form that combines these forms.

[0029] The dielectric ceramic composition of this embodiment exhibits excellent capacitance-temperature characteristics. Specifically, it shows a low capacitance-temperature change rate in the range from room temperature to 200°C or higher. The capacitance-temperature change rate (ΔC) is defined by the following equation.

number

[0030] The capacitance temperature change rate (ΔC) of the dielectric ceramic composition of this embodiment at temperatures between 25°C and 200°C is preferably between -50% and +20%. More preferably, it may be within ±20%. In the above formula, the capacitance at each temperature can be measured by the method described in the example.

[0031] [3] Method for producing dielectric ceramic composition: The dielectric ceramic composition of this embodiment may be manufactured, for example, by the following steps (A1) to (A3). However, the manufacturing method of the dielectric ceramic composition of this embodiment is not limited thereto.

[0032] (A1) A first calcination step in which BaCO3, TiO2 and RO are calcined by a solid-phase method to form a first calcined powder. (A2) A second calcination step in which the mixture of the first calcined powder obtained in the first calcination step of (A1) and WO3 is further calcined to form the base material of the dielectric ceramic composition. (A3)(A2) The base material and additives obtained in the second calcination process are subjected to a final calcination process to obtain a dielectric ceramic composition.

[0033] At this time, the base material is Ba(Ti (1-2x) R x W x It may be represented as O3 and may be a barium titanate-based compound having a perovskite structure. In the base material, some of the Ti sites of barium titanate may be substituted with R and W. R may be Mn and / or Mg. R may contain both Mn and Mg. x may satisfy 0.06 ≤ x ≤ 0.10.

[0034] The following provides a detailed explanation of each step. (A1) First calcination process In this process, BaCO3, TiO2, and RO are calcined to form the first calcined powder. BaCO3, TiO2, and RO may be weighed and mixed as raw materials, and the mixture may be heat-treated (calcined) by a solid-phase method. The amounts of BaCO3, TiO2, and RO may be adjusted so that the value of "x" of the base material obtained in the second calcination step (A2) is within the range of 0.06 ≤ x ≤ 0.10. When manufactured by a solid-phase method, for example, BaCO3, TiO2, and RO may be wet-mixed in a solvent. After drying the mixture, it may be coarsely ground and calcined to form the first calcined powder.

[0035] The solvent used in the wet mixing is not particularly limited. For example, water, alcohol-based solvents, glycol-based solvents, ketone-based solvents, ester-based solvents, ether-based solvents, aromatic solvents, or combinations of two or more of these can be used. Examples of alcohol-based solvents include ethanol, methanol, benzyl alcohol, and methoxyethanol. Examples of glycol-based solvents include ethylene glycol and diethylene glycol. Examples of ketone-based solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of ester-based solvents include butyl acetate, ethyl acetate, carbitol acetate, and butyl carbitol acetate. Examples of ether-based solvents include methyl cellosolve, ethyl cellosolve, butyl ether, and tetrahydrofuran. Examples of aromatic solvents include benzene, toluene, and xylene.

[0036] The amount of solvent used is preferably 0.5 to 10 times the total mass (sum) of BaCO3, TiO2, and RO. More preferably, the amount of solvent used is 0.7 to 5 times. Within this range, BaCO3, TiO2, and RO are sufficiently mixed.

[0037] In wet mixing, a wet ball mill or a stirring mill can be used. When using a wet ball mill, a large number of zirconia balls with a diameter of 0.1 mm to 10 mm may be used. The mixing time for wet mixing may be, for example, 8 hours to 48 hours, preferably 10 hours to 24 hours.

[0038] The calcination temperature is preferably 600°C to 1200°C, more preferably 700°C to 1150°C, and even more preferably 700°C to 1100°C.

[0039] The calcination top-hold time is not particularly limited, but is preferably between 1 and 5 hours, and more preferably between 1 and 3 hours. The firing atmosphere is also not particularly limited, and can be a vacuum, an air atmosphere, or an inert gas atmosphere such as nitrogen or argon.

[0040] Other firing conditions include a heating rate of preferably 50°C / hour to 500°C / hour, and more preferably 70°C / hour to 200°C / hour.

[0041] (A2) Second calcination process In this process, the mixture of the first calcined powder obtained in step (A1) and WO3 is further calcined to form the base material of the dielectric ceramic composition. The first calcined powder and WO3 may be weighed and mixed, and the mixture may be heat-treated (calcined) by a solid-phase method. The amount of WO3 may be adjusted so that the "x" of the base material obtained in the second calcination step is within the range of 0.06 ≤ x ≤ 0.10. When manufactured by a solid-phase method, for example, the first calcined powder and WO3 may be wet-mixed in a solvent. After drying the mixture, it may be coarsely ground and calcined to form the second calcined powder.

[0042] The solvent used in the wet mixing is not particularly limited. For example, water, alcohol-based solvents, glycol-based solvents, ketone-based solvents, ester-based solvents, ether-based solvents, aromatic solvents, or combinations of two or more of these can be used. Examples of alcohol-based solvents include ethanol, methanol, benzyl alcohol, and methoxyethanol. Examples of glycol-based solvents include ethylene glycol and diethylene glycol. Examples of ketone-based solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of ester-based solvents include butyl acetate, ethyl acetate, carbitol acetate, and butyl carbitol acetate. Examples of ether-based solvents include methyl cellosolve, ethyl cellosolve, butyl ether, and tetrahydrofuran. Examples of aromatic solvents include benzene, toluene, and xylene.

[0043] The amount of solvent used is preferably 0.5 to 10 times the total mass (sum) of the first calcined powder and WO3. More preferably, the amount of solvent used is 0.7 to 5 times. Within this range, the first calcined powder and WO3 are thoroughly mixed.

[0044] In wet mixing, a wet ball mill or a stirring mill can be used. When using a wet ball mill, a large number of zirconia balls with a diameter of 0.1 mm to 10 mm may be used. The mixing time for wet mixing may be, for example, 8 hours to 48 hours, preferably 10 hours to 24 hours.

[0045] The calcination temperature is preferably between 600°C and 1200°C, more preferably between 700°C and 1150°C, and even more preferably between 700°C and 1100°C. When the firing temperature is within the above range, it is preferable because the firing proceeds sufficiently and the resulting base material has fewer defects.

[0046] The calcination top-hold time is not particularly limited, but is preferably between 1 and 5 hours, and more preferably between 1 and 3 hours. The firing atmosphere is also not particularly limited, and can be a vacuum, an air atmosphere, or an inert gas atmosphere such as nitrogen or argon.

[0047] Other firing conditions include a heating rate of preferably 50°C / hour to 500°C / hour, and more preferably 70°C / hour to 200°C / hour.

[0048] (A3) Firing process In this process, the base material and additives obtained in step (A2) are fired to obtain a dielectric ceramic composition. The mixture obtained by mixing the base material and additives obtained in step (A2) may be molded and the molded body fired.

[0049] First, the base material obtained in step (A2) and the additive may be wet-mixed in a solvent. A slurry is prepared by wet-mixing the components of the dielectric ceramic composition of this embodiment in a solvent. The additive may include minor components of the dielectric ceramic composition, binders, plasticizers, dispersants, etc. The additive may also include lubricants, antistatic agents, etc.

[0050] The solvent used in wet mixing is not particularly limited. For example, water, alcohol-based solvents, glycol-based solvents, ketone-based solvents, ester-based solvents, ether-based solvents, aromatic solvents, or combinations of two or more of these can be used. Examples of alcohol-based solvents include ethanol, methanol, benzyl alcohol, and methoxyethanol. Examples of glycol-based solvents include ethylene glycol and diethylene glycol. Examples of ketone-based solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of ester-based solvents include butyl acetate, ethyl acetate, carbitol acetate, and butyl carbitol acetate. Examples of ether-based solvents include methyl cellosolve, ethyl cellosolve, butyl ether, and tetrahydrofuran. Examples of aromatic solvents include benzene, toluene, and xylene. Among these, alcohol-based solvents and aromatic solvents are preferred. These solvents have good solubility and dispersibility of various additives contained in the slurry. The alcohol-based solvent is preferably a low-boiling point solvent such as methanol or ethanol. The aromatic solvent is preferably a low-boiling point solvent such as toluene. The above solvents may be used individually or in combination of two or more in any combination and ratio. When two or more solvents are mixed, preferably, the above alcohol solvent and aromatic solvent are mixed.

[0051] The amount of solvent used is preferably 0.5 to 10 times the total mass (sum) of the base material and additives. More preferably, the amount of solvent used is 0.7 to 5 times. Within this range, the base material, additives, etc., are thoroughly mixed. Furthermore, the subsequent operation of removing the solvent can be easily performed.

[0052] The binders that may be included in the slurry are not particularly limited. Examples include polyvinyl alcohol (PVA), polyvinyl butyral (PVB), and acrylic resin. These binders may be used individually or in combination of two or more types.

[0053] The amount of binder used is not particularly limited. Preferably, the binder is 0.01% by mass or more and 20% by mass or less, relative to the total mass (sum) of the base material and additives. More preferably, the binder is 0.5% by mass or more and 15% by mass or less. This range improves the density of the molded article.

[0054] The plasticizers that may be included in the slurry are not particularly limited. Examples include phthalate-based plasticizers such as dioctyl phthalate (DOP), benzyl butyl phthalate, dibutyl phthalate, dihexyl phthalate, di(2-ethylhexyl) phthalate (DEHP), and di(2-ethylbutyl) phthalate; adipic acid-based plasticizers such as dihexyl adipate and di(2-ethylhexyl) adipate (DOA); glycol-based plasticizers such as ethylene glycol, diethylene glycol, and triethylene glycol; and glycol ester-based plasticizers such as triethylene glycol dibutyrate, triethylene glycol di(2-ethylbutyrate), and triethylene glycol di(2-ethylhexanoate). Among these, phthalate-based plasticizers such as dioctyl phthalate, dibutyl phthalate, and di(2-ethylhexyl) phthalate are preferred. Using phthalate-based plasticizers results in good flexibility of the green sheet produced from the slurry. The above-mentioned plasticizers may be used individually or in combination of two or more types.

[0055] The amount of plasticizer used is not particularly limited. Preferably, the amount of plasticizer is 5% to 50% by mass relative to the total mass of the binder added. More preferably, the amount of plasticizer is 10% to 50% by mass. Particularly preferably, the amount of plasticizer is 15% to 30% by mass. By setting the amount within the above range, sufficient effect as a plasticizer can be obtained.

[0056] The dispersants that may be included in the slurry are not particularly limited. Examples include phosphate ester dispersants and polycarboxylic acid dispersants. Among these, phosphate ester dispersants are preferred. The above dispersants may be used alone or in combination of two or more.

[0057] The amount of dispersant used is not particularly limited. Preferably, the amount of dispersant is 0.1% by mass or more and 5% by mass or less, relative to the total mass (sum) of the base material and additives. More preferably, the amount of dispersant is 0.3% by mass or more and 3% by mass or less. Even more preferably, the amount of dispersant is 0.5% by mass or more and 1.5% by mass or less. By setting the amount within the above range, sufficient dispersant effect can be obtained.

[0058] For wet mixing, a wet ball mill, a stirring mill, or a bead mill can be used. A wet ball mill may consist of numerous zirconia balls with a diameter of 0.1 mm to 10 mm. The mixing time for wet mixing may be, for example, 8 hours to 48 hours. Preferably, the mixing time is 10 hours to 24 hours.

[0059] Next, the slurry is molded to a predetermined size and shape to obtain a molded body. The molded body may be a sheet-formed product. For example, the slurry is formed into a sheet by a doctor blade method or a die coater method. The resulting sheets are then laminated and heat-press molded. If necessary, the molded body may be cut into a desired shape such as a chip shape. This results in the formation of a so-called green sheet.

[0060] The thickness of the green sheet (thickness after drying) is not particularly limited. Preferably, the thickness of the green sheet is 30 μm or less. More preferably, the thickness of the green sheet is 20 μm or less. On the other hand, there is no particular lower limit to the thickness of the green sheet (thickness after drying). The thickness of the green sheet is substantially 0.5 μm or more.

[0061] The above green sheets may be laminated to the desired thickness and then heat-pressed. The conditions during heat-pressing are not particularly limited. Preferably, the temperature during heat-pressing is 50°C to 150°C. Preferably, the pressure during heat-pressing is 10 MPa to 200 MPa. Preferably, the pressurizing time is 1 minute to 30 minutes. Examples of heat-pressing methods include warm isostatic pressing (WIP).

[0062] Subsequently, the layered green sheets are cut. This may produce green chips with the desired chip shape.

[0063] The binder components and other substances contained in the obtained green sheet (or green chips) are preferably removed by thermal decomposition (degreasing treatment). The conditions for the degreasing treatment depend on the type of binder used, but are not particularly limited. Preferably, the degreasing conditions are 180°C to 450°C. The degreasing treatment time is also not particularly limited. Preferably, the degreasing treatment time is 0.5 hours to 24 hours. The degreasing treatment is carried out in air or in an inert gas such as nitrogen or argon. From the viewpoint of ease of process control, the degreasing treatment is preferably carried out in air.

[0064] The final firing is carried out, as an example, by the following method. The final firing is performed on the molded body after the binder removal treatment. The temperature of the final firing may be 1400°C or lower. There is no particular limit to the lower limit of the final firing temperature. Preferably, the lower limit is 1000°C or higher. More preferably, the lower limit is 1150°C or higher. The temperature range for the final firing is more preferably 1200°C to 1400°C. Particularly preferably, the temperature range is 1230°C to 1360°C. The firing top-hold time is not particularly limited, but may be 1 hour to 5 hours. Preferably, the firing top-hold time is 1 hour to 3 hours. The heating conditions may be 50°C / h to 500°C / h. Preferably, the heating conditions are 70°C / h to 200°C / h. There is no particular limit to the firing atmosphere. It may be under an inert gas atmosphere or a reducing atmosphere. The reducing atmosphere may be a mixture of an inert gas with hydrogen and / or water vapor, etc.

[0065] The dielectric ceramic composition of this embodiment may be manufactured by the following steps (B1) to (B3).

[0066] (B1) A first calcination step in which TiO2, RO, and WO3 are calcined by a solid-phase method to form a first calcined powder. (B2) A second calcination step in which the mixture of the first calcined body obtained in step (B1) and BaCO3 is further calcined to form the base material of the dielectric ceramic composition. (B3) A final firing process in which the base material and additives obtained in process (B2) are fired to obtain a dielectric ceramic composition.

[0067] At this time, the base material is Ba(Ti (1-2x) R x W x It may be represented as O3 and may be a barium titanate-based compound having a perovskite structure. In the base material, some of the Ti sites of barium titanate may be substituted with R and W. R may be Mn and / or Mg. R may contain both Mn and Mg. x may satisfy 0.06 ≤ x ≤ 0.10.

[0068] The following provides a detailed explanation of each step. (B1) First calcination process In this process, TiO2, RO, and WO3 are calcined to form the first calcined powder. TiO2, RO, and WO3 may be weighed and mixed as raw materials, and the mixture may be heat-treated (calcined) by a solid-phase method. The amounts of TiO2, RO, and WO3 may be adjusted so that the value of "x" of the base material obtained in the second calcination step (B2) is within the range of 0.06 ≤ x ≤ 0.10. When manufactured by a solid-phase method, for example, TiO2, RO, and WO3 may be wet-mixed in a solvent. After drying the mixture, it may be coarsely ground and calcined to form the first calcined powder.

[0069] The solvent used in the wet mixing is not particularly limited. For example, water, alcohol-based solvents, glycol-based solvents, ketone-based solvents, ester-based solvents, ether-based solvents, aromatic solvents, or combinations of two or more of these can be used. Examples of alcohol-based solvents include ethanol, methanol, benzyl alcohol, and methoxyethanol. Examples of glycol-based solvents include ethylene glycol and diethylene glycol. Examples of ketone-based solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of ester-based solvents include butyl acetate, ethyl acetate, carbitol acetate, and butyl carbitol acetate. Examples of ether-based solvents include methyl cellosolve, ethyl cellosolve, butyl ether, and tetrahydrofuran. Examples of aromatic solvents include benzene, toluene, and xylene.

[0070] The amount of solvent used is preferably 0.5 to 10 times the total mass (sum) of TiO2, RO, and WO3. More preferably, the amount of solvent used is 0.7 to 5 times. Within this range, TiO2, RO, and WO3 are sufficiently mixed.

[0071] In wet mixing, a wet ball mill or a stirring mill can be used. When using a wet ball mill, a large number of zirconia balls with a diameter of 0.1 mm to 10 mm may be used. The mixing time for wet mixing may be, for example, 8 hours to 48 hours, preferably 10 hours to 24 hours.

[0072] The calcination temperature is preferably 600°C to 1200°C, more preferably 700°C to 1150°C, and even more preferably 700°C to 1100°C.

[0073] The calcination top-hold time is not particularly limited, but is preferably between 1 and 5 hours, and more preferably between 1 and 3 hours. The firing atmosphere is also not particularly limited, and can be a vacuum, an air atmosphere, or an inert gas atmosphere such as nitrogen or argon.

[0074] Other firing conditions include a heating rate of preferably 50°C / hour to 500°C / hour, and more preferably 70°C / hour to 200°C / hour.

[0075] (B2) Second calcination process In this process, the mixture of the first calcined powder obtained in step (B1) and BaCO3 is further calcined to form the base material of the dielectric ceramic composition. The first calcined powder and BaCO3 may be weighed and mixed, and the mixture may be heat-treated (calcined) by a solid-phase method. The amount of BaCO3 may be adjusted so that the value of "x" of the base material obtained in the second calcination step is within the range of 0.06 ≤ x ≤ 0.10. When manufactured by a solid-phase method, for example, the first calcined powder and BaCO3 may be wet-mixed in a solvent. After drying the mixture, it may be coarsely ground and calcined to form the second calcined powder.

[0076] The solvent used in the wet mixing is not particularly limited. For example, water, alcohol-based solvents, glycol-based solvents, ketone-based solvents, ester-based solvents, ether-based solvents, aromatic solvents, or combinations of two or more of these can be used. Examples of alcohol-based solvents include ethanol, methanol, benzyl alcohol, and methoxyethanol. Examples of glycol-based solvents include ethylene glycol and diethylene glycol. Examples of ketone-based solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of ester-based solvents include butyl acetate, ethyl acetate, carbitol acetate, and butyl carbitol acetate. Examples of ether-based solvents include methyl cellosolve, ethyl cellosolve, butyl ether, and tetrahydrofuran. Examples of aromatic solvents include benzene, toluene, and xylene.

[0077] The amount of solvent used is preferably 0.5 to 10 times the total mass (sum) of the first calcined powder and BaCO3. More preferably, the amount of solvent used is 0.7 to 5 times. Within this range, the first calcined powder and BaCO3 are thoroughly mixed.

[0078] In wet mixing, a wet ball mill or a stirring mill can be used. When using a wet ball mill, a large number of zirconia balls with a diameter of 0.1 mm to 10 mm may be used. The mixing time for wet mixing may be, for example, 8 hours to 48 hours, preferably 10 hours to 24 hours.

[0079] The calcination temperature is preferably between 600°C and 1200°C, more preferably between 700°C and 1150°C, and even more preferably between 700°C and 1100°C. When the firing temperature is within the above range, it is preferable because the firing proceeds sufficiently and the resulting base material has fewer defects.

[0080] The calcination top-hold time is not particularly limited, but is preferably between 1 and 5 hours, and more preferably between 1 and 3 hours. The firing atmosphere is also not particularly limited, and can be a vacuum, an air atmosphere, or an inert gas atmosphere such as nitrogen or argon.

[0081] Other firing conditions include a heating rate of preferably 50°C / hour to 500°C / hour, and more preferably 70°C / hour to 200°C / hour.

[0082] (B3) Firing Process In this process, the base material and additives obtained in step (B2) are fired to obtain a dielectric ceramic composition. The mixture obtained by mixing the base material and additives obtained in step (B2) may be molded and the molded body fired.

[0083] First, the base material obtained in step (B2) and the additive may be wet-mixed in a solvent. A slurry is prepared by wet-mixing the components of the dielectric ceramic composition of this embodiment in a solvent. The additive may include minor components of the dielectric ceramic composition, binders, plasticizers, dispersants, etc. The additive may also include lubricants, antistatic agents, etc.

[0084] The solvent used in wet mixing is not particularly limited. For example, water, alcohol-based solvents, glycol-based solvents, ketone-based solvents, ester-based solvents, ether-based solvents, aromatic solvents, or combinations of two or more of these can be used. Examples of alcohol-based solvents include ethanol, methanol, benzyl alcohol, and methoxyethanol. Examples of glycol-based solvents include ethylene glycol and diethylene glycol. Examples of ketone-based solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of ester-based solvents include butyl acetate, ethyl acetate, carbitol acetate, and butyl carbitol acetate. Examples of ether-based solvents include methyl cellosolve, ethyl cellosolve, butyl ether, and tetrahydrofuran. Examples of aromatic solvents include benzene, toluene, and xylene. Among these, alcohol-based solvents and aromatic solvents are preferred. These solvents have good solubility and dispersibility of various additives contained in the slurry. The alcohol-based solvent is preferably a low-boiling point solvent such as methanol or ethanol. The aromatic solvent is preferably a low-boiling point solvent such as toluene. The above solvents may be used individually or in combination of two or more in any combination and ratio. When two or more solvents are mixed, preferably, the above alcohol solvent and aromatic solvent are mixed.

[0085] The amount of solvent used is preferably 0.5 to 10 times the total mass (sum) of the base material and additives. More preferably, the amount of solvent used is 0.7 to 5 times. Within this range, the base material, additives, etc., are thoroughly mixed. Furthermore, the subsequent operation of removing the solvent can be easily performed.

[0086] The binders that may be included in the slurry are not particularly limited. Examples include polyvinyl alcohol (PVA), polyvinyl butyral (PVB), and acrylic resin. These binders may be used individually or in combination of two or more types.

[0087] The amount of binder used is not particularly limited. Preferably, the binder is 0.01% by mass or more and 20% by mass or less, relative to the total mass (sum) of the base material and additives. More preferably, the binder is 0.5% by mass or more and 15% by mass or less. This range improves the density of the molded article.

[0088] The plasticizers that may be included in the slurry are not particularly limited. Examples include phthalate-based plasticizers such as dioctyl phthalate (DOP), benzyl butyl phthalate, dibutyl phthalate, dihexyl phthalate, di(2-ethylhexyl) phthalate (DEHP), and di(2-ethylbutyl) phthalate; adipic acid-based plasticizers such as dihexyl adipate and di(2-ethylhexyl) adipate (DOA); glycol-based plasticizers such as ethylene glycol, diethylene glycol, and triethylene glycol; and glycol ester-based plasticizers such as triethylene glycol dibutyrate, triethylene glycol di(2-ethylbutyrate), and triethylene glycol di(2-ethylhexanoate). Among these, phthalate-based plasticizers such as dioctyl phthalate, dibutyl phthalate, and di(2-ethylhexyl) phthalate are preferred. Using phthalate-based plasticizers results in good flexibility of the green sheet produced from the slurry. The above-mentioned plasticizers may be used individually or in combination of two or more types.

[0089] The amount of plasticizer used is not particularly limited. Preferably, the amount of plasticizer is 5% to 50% by mass relative to the total mass of the binder added. More preferably, the amount of plasticizer is 10% to 50% by mass. Particularly preferably, the amount of plasticizer is 15% to 30% by mass. By setting the amount within the above range, sufficient effect as a plasticizer can be obtained.

[0090] The dispersants that may be included in the slurry are not particularly limited. Examples include phosphate ester dispersants and polycarboxylic acid dispersants. Among these, phosphate ester dispersants are preferred. The above dispersants may be used alone or in combination of two or more.

[0091] The amount of dispersant used is not particularly limited. Preferably, the amount of dispersant is 0.1% by mass or more and 5% by mass or less, relative to the total mass (sum) of the base material and additives. More preferably, the amount of dispersant is 0.3% by mass or more and 3% by mass or less. Even more preferably, the amount of dispersant is 0.5% by mass or more and 1.5% by mass or less. By setting the amount within the above range, sufficient dispersant effect can be obtained.

[0092] For wet mixing, a wet ball mill, a stirring mill, or a bead mill can be used. A wet ball mill may consist of numerous zirconia balls with a diameter of 0.1 mm to 10 mm. The mixing time for wet mixing may be, for example, 8 hours to 48 hours. Preferably, the mixing time is 10 hours to 24 hours.

[0093] Next, the slurry is molded to a predetermined size and shape to obtain a molded body. The molded body may be a sheet-formed product. For example, the slurry is formed into a sheet by a doctor blade method or a die coater method. The resulting sheets are then laminated and heat-press molded. If necessary, the molded body may be cut into a desired shape such as a chip shape. This results in the formation of a so-called green sheet.

[0094] The thickness of the green sheet (thickness after drying) is not particularly limited. Preferably, the thickness of the green sheet is 30 μm or less. More preferably, the thickness of the green sheet is 20 μm or less. On the other hand, there is no particular lower limit to the thickness of the green sheet (thickness after drying). The thickness of the green sheet is substantially 0.5 μm or more.

[0095] The above green sheets may be laminated to the desired thickness and then heat-pressed. The conditions during heat-pressing are not particularly limited. Preferably, the temperature during heat-pressing is 50°C to 150°C. Preferably, the pressure during heat-pressing is 10 MPa to 200 MPa. Preferably, the pressurizing time is 1 minute to 30 minutes. Examples of heat-pressing methods include warm isostatic pressing (WIP).

[0096] Subsequently, the layered green sheets are cut. This may produce green chips with the desired chip shape.

[0097] The binder components and other substances contained in the obtained green sheet (or green chips) are preferably removed by thermal decomposition (degreasing treatment). The conditions for the degreasing treatment depend on the type of binder used, but are not particularly limited. Preferably, the degreasing conditions are 180°C to 450°C. The degreasing treatment time is also not particularly limited. Preferably, the degreasing treatment time is 0.5 hours to 24 hours. The degreasing treatment is carried out in air or in an inert gas such as nitrogen or argon. From the viewpoint of ease of process control, the degreasing treatment is preferably carried out in air.

[0098] The final firing is carried out, as an example, by the following method. The final firing is performed on the molded body after the binder removal treatment. The temperature of the final firing may be 1400°C or lower. There is no particular limit to the lower limit of the final firing temperature. Preferably, the lower limit is 1000°C or higher. More preferably, the lower limit is 1150°C or higher. The temperature range for the final firing is more preferably 1200°C to 1400°C. Particularly preferably, the temperature range is 1230°C to 1360°C. The firing top-hold time is not particularly limited, but may be 1 hour to 5 hours. Preferably, the firing top-hold time is 1 hour to 3 hours. The heating conditions may be 50°C / h to 500°C / h. Preferably, the heating conditions are 70°C / h to 200°C / h. There is no particular limit to the firing atmosphere. It may be under an inert gas atmosphere or a reducing atmosphere. The reducing atmosphere may be a mixture of an inert gas with hydrogen and / or water vapor, etc.

[0099] [4] Applicable fields for dielectric ceramic compositions: The dielectric ceramic composition of this embodiment can be used in various electronic components. In particular, the dielectric ceramic composition is suitable for use in electronic components where reliability is required at high temperatures (e.g., 200°C or higher). An example of such an electronic component is a capacitor containing the dielectric ceramic composition as a dielectric. Another example is a multilayer ceramic capacitor (MLCC) containing the dielectric ceramic composition as a dielectric.

[0100] These electronic components are used, for example, in the power module substrate of an electric vehicle or near that power module substrate, and require high performance and reliability. For example, they are used in power modules equipped with SiC semiconductors. MLCCs containing dielectric ceramic compositions can be manufactured, for example, by the following method.

[0101] First, a conductive paste for internal electrodes is printed onto the green sheet obtained in step (A3) or (B3) above. The printing method may be, for example, screen printing. The conductive paste for internal electrodes can be made of Cu, Ni, Pt, Pd, Ag, etc. Multiple green sheets printed with the conductive paste for internal electrodes are stacked to form a laminate.

[0102] Next, the laminate is sandwiched between green sheets that do not have conductive paste for the internal electrodes printed on them. After this, the laminate is pressed together. Then, it is cut as needed to form green chips. After that, the green chips are debindered and fired to obtain capacitor chip bodies. The firing conditions may be the same as those for steps (A3) and (B3) above. In addition, the obtained capacitor chip bodies may be further annealed during firing in a reducing atmosphere. This makes it possible to re-oxidize the dielectric layer.

[0103] Next, each end face of the internal electrode exposed from the end face of the capacitor chip body is connected to the external electrode. For example, the external electrode may be formed by applying a conductive paste for the external electrode to the end face. As the conductive paste for the external electrode, the materials listed for the conductive paste for the internal electrode may be used. Alternatively, alloys such as Cu, Ag, Ag-10Pd, Ag-coated Cu, and / or carbon materials such as graphite may be used as the paste. Furthermore, if necessary, a coating layer may be formed on the capacitor chip body by plating.

[0104] One example of an electronic component is a multilayer ceramic capacitor. However, the electronic components according to this embodiment are not limited to this. For example, various other components can be mentioned, such as high-frequency modules, thermistor electronic components, or composite components thereof.

[0105] [5] Examples: Examples and comparative examples of the present invention will be explained using a table. However, the technical scope of the present invention is not limited to the following examples. [Raw materials] In the examples and comparative examples, the following were used as raw materials. BaCO3: Rare Metallic Co., Ltd. Ba-40-26-0060 TiO2: Mitsuwa Chemical Co., Ltd. Titanium Dioxide IV 3N MgO: Rare Metallic Co., Ltd. MG-76-20-0130 Mn3O4: High Purity Chemical Laboratory Co., Ltd. MNO03PB WO3: High Purity Chemical Laboratory Co., Ltd. WWO03PB

[0106] Table 1 shows the compositions of the dielectric ceramic compositions of the examples and comparative examples. [Table 1]

[0107] Table 1, x is the base material Ba(Ti (1-2x) R x W x ) corresponds to x in O3. In Table 1, "calcination" represents the number of calcination steps in the process of obtaining the base material of the dielectric ceramic composition. One step means that the calcination step was performed once, and two steps means that the calcination step was performed twice.

[0108] [Example A1] BaCO3, TiO2, and MgO were weighed using an electronic balance so that x = 0.06. Pure water was added to the weighed materials to a solid content concentration of 33 wt%. Then, wet mixing was carried out for 16 hours using a rotary ball mill. A φ3 mm ZrO2 ball was used in the rotary ball mill. After that, the slurry was removed and vat-dried in air at 100°C. The resulting dried powder was coarsely ground using a mortar and pestle. The resulting powder was calcined in air in an alumina crucible (first calcination step). Calcination was carried out under conditions of 1000°C for 3 hours (heating increased at 100°C / hour).

[0109] To the obtained first calcined powder, WO3 was weighed using an electronic balance so that x = 0.06, and then added, followed by the addition of pure water to achieve a solid content concentration of 33 wt%. Wet mixing was then carried out for 16 hours using a rotary ball mill. A φ3 mm ZrO2 ball was used in the rotary ball mill. The slurry was then removed and vat-dried in air at 100°C. The resulting dried powder was coarsely ground using a mortar and pestle. The resulting powder was calcined in an alumina crucible in air (second calcination step). Calcination was carried out at 1000°C for 3 hours (heating at 100°C / hour). The obtained second calcined powder was coarsely ground using a mortar and pestle and formed into pellets. The resulting pellets were then fully calcined at 1300°C for 5 hours (heating at 100°C / hour).

[0110] [Example A2] A dielectric ceramic composition was prepared under the same conditions as in Example A1, except that BaCO3, TiO2, MgO, and WO3 were weighed so that x = 0.10.

[0111] [Example A3] A dielectric ceramic composition was prepared under the same conditions as in Example A1, except that BaCO3, TiO2, MnO, and WO3 were weighed so that x = 0.06.

[0112] [Example A4] A dielectric ceramic composition was prepared under the same conditions as in Example A1, except that BaCO3, TiO2, MnO, and WO3 were weighed so that x = 0.10.

[0113] [Example B1] TiO2, MgO, and WO3 were weighed using an electronic balance so that x = 0.06. Pure water was added to the weighed materials to a solid content concentration of 33 wt%. Then, wet mixing was carried out for 16 hours using a rotary ball mill. A φ3 mm ZrO2 ball was used in the rotary ball mill. After that, the slurry was removed and vat-dried in air at 100°C. The resulting dried powder was coarsely ground using a mortar and pestle. The resulting powder was calcined in air in an alumina crucible (first calcination step). Calcination was carried out under conditions of 1000°C for 3 hours (heating increased at 100°C / hour).

[0114] To the obtained first calcined powder, BaCO3 was weighed using an electronic balance so that x = 0.06 and added, and pure water was added to achieve a solid content concentration of 33 wt%. Then, wet mixing was carried out for 16 hours using a rotary ball mill. A φ3 mm ZrO2 ball was used in the rotary ball mill. After that, the slurry was removed and vat-dried in air at 100°C. The obtained dried powder was coarsely ground using a mortar and pestle. The obtained powder was calcined in air in an alumina crucible (second calcination step). Calcination was carried out under the conditions of 1000°C × 3 hours (heating increase at 100°C / hour). The obtained second calcined powder was coarsely ground using a mortar and pestle and molded into pellets. The obtained pellets were fully calcined under the conditions of 1300°C × 5 hours (heating increase at 100°C / hour).

[0115] [Example B2] A dielectric ceramic composition was prepared under the same conditions as in Example B1, except that TiO2, MgO, WO3, and BaCO3 were weighed so that x = 0.10.

[0116] [Comparative Example 1] BaCO3, TiO2, MgO, and WO3 were weighed using an electronic balance so that x = 0.10. Pure water was added to the weighed materials to a solid content concentration of 33 wt%. Wet mixing was then carried out for 16 hours using a rotary ball mill. A φ3 mm ZrO2 ball was used in the rotary ball mill. The slurry was then removed and vat-dried in air at 100°C. The resulting dried powder was coarsely ground using a mortar and pestle. The resulting powder was calcined in an alumina crucible in air. Calcination was carried out under conditions of 1000°C for 3 hours (heating at 100°C / hour). The resulting calcined powder was coarsely ground using a mortar and pestle and XRD measurement was performed.

[0117] [Comparative Example 2] BaCO3, TiO2, MnO, and WO3 were weighed using an electronic balance so that x = 0.10. Pure water was added to the weighed materials to a solid content concentration of 33 wt%. Wet mixing was then carried out for 16 hours using a rotary ball mill. A φ3 mm ZrO2 ball was used in the rotary ball mill. The slurry was then removed and vat-dried in air at 100°C. The resulting dried powder was coarsely ground using a mortar and pestle. The resulting powder was calcined in an alumina crucible in air. Calcination was carried out under conditions of 1000°C for 3 hours (heating at 100°C / hour). The resulting calcined powder was coarsely ground using a mortar and pestle and XRD measurement was performed.

[0118] [Comparative Example A5] A dielectric ceramic composition was prepared under the same conditions as in Example A1, except that BaCO3, TiO2, MnO, and WO3 were weighed so that x = 0.02.

[0119] [Example A6] A dielectric ceramic composition was prepared under the same conditions as in Example A1, except that BaCO3, TiO2, MnO, and WO3 were weighed so that x = 0.04.

[0120] [Example B3] A dielectric ceramic composition was prepared under the same conditions as in Example B1, except that TiO2, MgO, WO3, and BaCO3 were weighed so that x = 0.02.

[0121] [Example B4] A dielectric ceramic composition was prepared under the same conditions as in Example B1, except that TiO2, MgO, WO3, and BaCO3 were weighed so that x = 0.04.

[0122] [evaluation] The dielectric ceramic compositions obtained in the above examples and comparative examples were evaluated as follows.

[0123] (1) STEM / WDS or STEM / EELS analysis The R and W content in the dielectric grains of each dielectric ceramic composition was analyzed at a total of four locations using STEM / WDS or STEM / EELS. The average value of the four locations was calculated to determine the RO and WO3 content in the base material.

[0124] (2)XRD analysis XRD analysis was performed on the dielectric ceramic compositions of the examples and comparative examples. Graphs of the XRD analysis results obtained for the examples and comparative examples are shown in Figures 1A, 1B, 1C, 1D, 1E, and 1F.

[0125] (3) Rate of change in volume temperature The capacitance temperature change rate of the dielectric ceramic compositions obtained by firing in the examples and comparative examples was evaluated. The capacitance temperature change rate was evaluated by measuring the capacitance of the dielectric ceramic composition in a temperature range from 25°C to 250°C, and calculating the rate of change of capacitance at each temperature relative to the capacitance at 25°C (unit: %) from the measured capacitance values ​​according to the following formula.

number

[0126] Capacitance was measured using electrodes fabricated by gold sputtering from 2 mm square samples cut from sintered pellets of dielectric ceramic compositions obtained in the examples and comparative examples. An LCR meter was used for capacitance measurement. The LCR meter used was a Wayne Kerr Electronics 6440B. The measurement conditions were a frequency of 1 kHz. Graphs of the capacitance temperature change rate obtained for the examples and comparative examples are shown in Figures 2A and 2B.

[0127] The capacitance-temperature characteristics were evaluated as follows. ○: The rate of change in volume temperature ΔC from -55℃ to 200℃ is between -50% and +20%. ×: ΔC falls outside the range of "-50% to +20%".

[0128] (4) DC bias attenuation rate The change in dielectric constant with respect to DC bias was measured for the dielectric ceramic compositions of the examples and comparative examples. The dielectric constant was measured by measuring the PE hysteresis and converting it to dielectric constant. A Model 6252 Rev.C manufactured by Toyo Corporation was used to measure the PE hysteresis. The measurement conditions were a frequency of 100 Hz. Graphs of the change in dielectric constant with respect to DC bias obtained for the examples and comparative examples are shown in Figures 3A and 3B.

[0129] The DC bias attenuation rate was evaluated as follows. ○: DC bias attenuation rate ≤ 50% ×: DC bias attenuation rate > 50% The DC bias attenuation rate was calculated using the zero-bias dielectric constant as a reference, and was defined as the percentage decrease in dielectric constant when an electric field strength of ±100kV / cm was applied, according to the following formula. DC bias attenuation rate (%) = [1 - (dielectric constant when ±100kV / cm is applied / zero bias dielectric constant)] × 100

[0130] Table 2 shows the measurement results of the RO and WO3 content contained in the base material of the dielectric porcelain compositions of the examples and comparative examples. [Table 2]

[0131] Table 3 shows the evaluation results of the dielectric ceramic compositions of the examples and comparative examples. [Table 3]

[0132] Referring to Figures 1A to 1F, the dielectric ceramic compositions of Examples A1 to A4, Examples B1 and B2, and Comparative Examples A5, A6, B3, and B4, which underwent a two-stage calcination process, showed no peaks of impurity phases in XRD, indicating that the dielectric ceramic compositions were single-phase. On the other hand, the dielectric ceramic compositions of Comparative Examples 1 and 2, which were produced by a one-stage calcination process, showed peaks of impurity phases, indicating that the dielectric ceramic compositions were not single-phase.

[0133] Referring to Table 2, the RO and WO3 content in the base material of the dielectric ceramic composition was in the range of 5.0% by weight or more and 11.0% by weight or less relative to the total base material in Examples A1 to A4, B1, B2, Comparative Example 1 and Comparative Example 2. On the other hand, Comparative Examples A5, A6, B3 and B4 were outside the range of 5.0% by weight or more and 11.0% by weight or less.

[0134] From the results in Table 3, Figure 2A, and Figure 2B, it can be seen that the dielectric ceramic compositions of Examples A1 to A4, B1, and B2 exhibit excellent capacitance-temperature characteristics and satisfy the X9M characteristics. On the other hand, the dielectric ceramic compositions of Comparative Examples A5, A6, B3, and B4 showed reduced capacitance-temperature characteristics and did not satisfy the X9M characteristics (-50% ≤ ΔC ≤ +20%).

[0135] Therefore, the multilayer ceramic capacitor to which the dielectric ceramic composition of this embodiment is applied exhibits excellent temperature characteristics. In other words, the multilayer ceramic capacitor to which the dielectric ceramic composition of this embodiment is applied exhibits good temperature characteristics even at high temperatures exceeding 200°C and has excellent high-temperature reliability.

[0136] From the results in Table 3, Figure 3A, and Figure 3B, it can be seen that the dielectric ceramic compositions of Examples A1 to A4, B1, and B2 show little change in dielectric constant even when the DC voltage increases from 0V to ±100kV / cm when a DC voltage is applied, and the DC bias attenuation rate satisfies 50% or less. On the other hand, it can be seen that the dielectric ceramic compositions of Comparative Examples A5, A6, B3, and B4 show a large decrease in dielectric constant as the DC voltage increases from 0V to ±100kV / cm when a DC voltage is applied.

[0137] Therefore, the dielectric ceramic composition according to this embodiment exhibits excellent DC bias characteristics. In other words, a multilayer ceramic capacitor to which the dielectric ceramic composition according to this embodiment is applied exhibits high capacitance characteristics because the dielectric constant changes little and the capacitance does not decrease even when a DC voltage is applied.

[0138] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0139] It should be noted that the execution order of operations, procedures, steps, and stages in the apparatus, systems, programs, and methods shown in the claims, specifications, and drawings is not explicitly stated as "before," "prior to," etc., and that these can be implemented in any order unless the output of a previous process is used in a later process. Even if the operation flow in the claims, specifications, and drawings is described using phrases such as "first," "next," etc. for convenience, it does not mean that it is essential to perform the operations in that order.

Claims

1. Ba(Ti （１－２ｘ） R ｘ W ｘ ) O ３ It contains components derived from the base material represented by, The aforementioned R is Mn and / or Mg, The aforementioned x is a dielectric ceramic composition satisfying 0.06 ≤ x ≤ 0.

10.

2. Ba(Ti （１－２ｘ） R ｘ W ｘ ) O ３ It contains components derived from the base material represented by, The aforementioned R is Mn and / or Mg, The above x satisfies 0.06 ≤ x ≤ 0.10, A dielectric porcelain composition obtained by firing at least the base material and additives, The base material is BaCO ３ , TiO ２ and RO are subjected to first calcination by a solid-phase method, and then used as a mixture with WO ３ to obtain a calcined powder obtained by further second calcination as the base material, a dielectric porcelain composition.

3. Ba(Ti （１－２ｘ） R ｘ W ｘ ) O ３ It contains components derived from the base material represented by, The aforementioned R is Mn and / or Mg, The above x satisfies 0.06 ≤ x ≤ 0.10, A dielectric porcelain composition obtained by firing at least the base material and additives, The aforementioned base material is TiO ２ RO and WO ３ After the first calcination using the solid phase method, BaCO3 ３ A dielectric ceramic composition comprising a mixture of the above, and a calcined powder obtained by a second calcination, with the calcined powder serving as the base material.

4. Ba(Ti （１－２ｘ） R ｘ W ｘ ) O ３ It contains dielectric grains derived from the base material represented by The aforementioned R is Mn and / or Mg, The above x satisfies 0.06 ≤ x ≤ 0.10, A dielectric ceramic composition in which the dielectric grains do not have a core-shell structure.

5. Ba(Ti （１－２ｘ） R ｘ W ｘ ) O ３ It contains dielectric grains derived from the base material represented by The aforementioned R is Mn and / or Mg, The above x satisfies 0.06 ≤ x ≤ 0.10, A dielectric ceramic composition in which the dielectric grains have a uniform structure.

6. The dielectric ceramic composition according to claim 5, wherein the standard deviation of the Ti concentration in the dielectric grain is 1% or less.

7. RO and WO included in the aforementioned base material ３ A dielectric ceramic composition according to any one of claims 1 to 6, wherein the content of is 5.0% by weight or more and 11.0% by weight or less of the entire base material.

8. The dielectric ceramic composition according to any one of claims 1 to 7, wherein the base material has a perovskite structure.

9. A multilayer ceramic capacitor comprising a dielectric ceramic composition according to any one of claims 1 to 8 as a dielectric.

10. BaCO ３ , TiO ２ and a first calcination step in which RO is calcined by a solid-phase method to form a first calcined powder, The first calcined flour and WO ３ A second calcination step is performed, in which the mixture is further calcined to form the base material of the dielectric ceramic composition. The process includes a firing step in which the base material and additives are fired to obtain a dielectric porcelain composition, The aforementioned base material is Ba(Ti （１－２ｘ） R ｘ W ｘ ) O ３ It is represented as, The aforementioned R is Mn and / or Mg, The method for manufacturing a dielectric ceramic composition, wherein x satisfies 0.06 ≤ x ≤ 0.

10.

11. TiO ２ RO and WO ３ A first calcination step in which the first calcined powder is formed by calcining using a solid-phase method, The first calcined powder and BaCO ３ A second calcination step is performed, in which the mixture is further calcined to form the base material of the dielectric ceramic composition. The process includes a firing step in which the base material and additives are fired to obtain a dielectric porcelain composition, The aforementioned base material is Ba(Ti （１－２ｘ） R ｘ W ｘ ) O ３ It is represented as, The aforementioned R is Mn and / or Mg, The method for manufacturing a dielectric ceramic composition, wherein x satisfies 0.06 ≤ x ≤ 0.10.

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