JP2017119607A - Dielectric body ceramic composition and method for producing the same, and ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric body ceramic composition which has capacity-temperature characteristics usable in the range of -55-200°C, and has a high insulation resistance value.SOLUTION: The dielectric body ceramic composition is provided that contains a compound oxide represented by compositional formula (1): xBaTiO(1-x)BaTiO(x is 0.20-0.50) as a main component, and contains 0.5 mol% or more of SiOwith respect to 100 mol% of the compound oxide. A method for producing a dielectric ceramic composition is provided that comprises mixing BaTiO, BaTiOwith a glass component represented by SiO, then molding the resultant mixture thereby obtaining a molded body, and firing the molded body at a temperature of 1,250°C or higher, the molar ratio of the BaTiOand the BaTiObeing 0.20:0.80 to 0.50:0.05, and the amount of glass component represented by SiObeing 0.50 mol% or more with respect to 100 mol% of the total of the BaTiOand the BaTiO. It is preferred that 0.1 mol% or more of an oxide of manganese in terms of MnO is added to 100 mol% of the total of the BaTiOand the BaTiOin the above step of obtaining the molded body.SELECTED DRAWING: None

Description

  The present invention relates to a dielectric ceramic composition, a method for producing the same, and a ceramic electronic component.

  With the spread of smartphones and tablets, electronic components used in these devices are required to be smaller and higher in performance. Of course, multilayer ceramic capacitors (MLCC) used as multilayer capacitors are also small in size. Large capacity is required.

  In particular, in recent years, as a characteristic required for in-vehicle MLCC, the temperature characteristic of capacitance is the X8R characteristic of EIA (American Electronic Industry Association) standard (within ΔC = ± 15% from −55 ° C. to 150 ° C .; There are demands for those satisfying the “X8R characteristics”) and having a high withstand voltage of 50 V or higher.

  As the performance of automobiles increases, the use of in-vehicle electrical components tends to increase further in the future, and the problem of increased storage space and weight of wiring becomes apparent. And the solution by making it possible to install an electrical board | substrate in the high temperature part around an engine with respect to the said problem is achieved. In addition, with the spread of electric vehicles, it is required to mount an electrical board directly on the periphery of the motor, which becomes high temperature, for the purpose of improving the performance of the motor and making it compact. As described above, as the usage environment of the in-vehicle electrical component becomes high, MLCC also exhibits a good capacity-temperature characteristic even at a high temperature of 200 ° C., even under a severer environment than the X8R characteristic. More and more usable products will be needed in the future.

  In order to solve this problem, development of a dielectric material having a high Curie point, a good capacity-temperature characteristic, and high reliability has been actively conducted in recent years.

For example, Patent Document 1 discloses a composition in which BaTiO ₃ particles containing Fe or K are dispersed in a BaTi ₂ O ₅ precursor solution.

JP 2008-195555 A

  However, since the dielectric ceramic composition described in Patent Document 1 contains Fe or K, there is a problem that insulation is low. If the insulation is low, semiconductorization proceeds and dielectric breakdown is likely to occur. Therefore, even if a ceramic electronic component such as a capacitor is produced using the above composition, the reliability is lowered.

  Accordingly, an object of the present invention is to provide a dielectric ceramic composition having a capacity-temperature characteristic that can be used in a range of −55 ° C. or more and 200 ° C. or less and having a high insulation resistance value.

The present inventors have intensively studied to solve the above problems. As a result, a dielectric ceramic composition containing a barium titanate-based composite oxide having a specific composition as a main component and containing a specific amount or more of SiO ₂ with respect to 100 mol% of the composite oxide solves the above problems. As a result, the present invention has been completed.

That is, the present invention is represented by the composition formula (1): xBaTiO _3. (1-x) BaTi ₂ O ₅ (wherein x in the composition formula (1) is 0.20 or more and 0.50 or less). Complex oxide as a main component,
A dielectric ceramic composition comprising 0.5 mol% or more of SiO ₂ with respect to 100 mol% of the composite oxide.

  ADVANTAGE OF THE INVENTION According to this invention, while having the capacity | capacitance temperature characteristic which can be used in the range of -55 degreeC or more and 200 degrees C or less, the dielectric ceramic composition which has a high insulation resistance value is provided. That is, a dielectric ceramic composition having a capacity-temperature characteristic that can be used even in a severe temperature environment and having excellent insulating properties is provided.

4 is a graph plotting capacity change rates at various temperatures of dielectric ceramic compositions according to Examples 2 and 3. FIG. It is the graph which plotted the capacity | capacitance change rate in each temperature of the dielectric ceramic composition which concerns on the comparative examples 1 and 3.

  Embodiments of the present invention will be described below.

The first form of the present invention is the composition formula (1): xBaTiO _3. (1-x) BaTi ₂ O ₅ (wherein x in the composition formula (1) is 0.20 or more and 0.50 or less. Is a dielectric ceramic composition containing 0.5 mol% or more of SiO ₂ with respect to 100 mol% of the composite oxide as a main component.

  In the present specification, the main component refers to the one having the largest number of moles in the compound constituting the dielectric ceramic composition.

  As described above, in recent years, not only does the temperature characteristic of capacitance satisfy the X8R characteristic, but it also has a capacity-temperature characteristic that can be used even in a harsher environment (especially at a high temperature of 200 ° C.). MLCCs are sought after. In order to produce such MLCC, a dielectric ceramic composition having a capacity-temperature change rate (Tc) within ± 22% within a range of −55 ° C. or more and 200 ° C. or less is required.

Thus, in order to satisfy the capacity-temperature characteristics that can withstand use at higher temperatures as compared with the prior art, high-temperature dielectric materials such as KNbO ₃ , K _0.5 Na _0.5 NbO ₃ , NaNbO _3, etc. Research is underway. However, in the former two types of these dielectric materials, potassium (K) is scattered (sublimated) in the firing process, resulting in lattice defects in the obtained dielectric material, thereby reducing insulation. There is a problem. If the insulation is low, semiconductorization proceeds and dielectric breakdown is likely to occur. As a result, when the dielectric material is applied to a ceramic electronic component such as a capacitor, there is a problem that the reliability of the ceramic electronic component is lowered. In addition, the scattering of potassium (K) makes it difficult to manage the production process, and there is a disadvantage that productivity is lowered. Furthermore, since the dielectric material uses expensive niobium (Nb), it is disadvantageous in terms of cost.

  On the other hand, the technique disclosed in the above-mentioned Patent Document 1 does not require expensive niobium (Nb) and uses a relatively inexpensive barium titanate-based dielectric material. However, since the composition disclosed in Patent Document 1 contains iron (Fe) or potassium (K), the insulating property is not good. Similarly to the above, a capacitor is manufactured using the composition. However, the problem that the reliability will fall arises.

In order to solve such problems, the present inventors have intensively studied. As a result, the composite oxide represented by the composition formula (1): xBaTiO _3. (1-x) BaTi ₂ O ₅ as a main component (however, in the composition formula (1), x is within a specific range). And a dielectric ceramic composition containing a specific amount or more of SiO ₂ as a secondary component has been found to solve the above problems.

Compositional formula: Barium dititanate represented by BaTi ₂ O ₅ has a monoclinic structure at room temperature (a = 16.892８９, b = 3.930Å, c = 9.410Å, β = 103) 0.03), having spontaneous polarization in the b-axis direction. Further, according to the projection onto the ac plane, it has three types of oxygen octahedrons (TiO ₆ , Ti ₂ O ₆ , Ti ₃ O ₆ ), and one of these is deformed to be ferroelectric. Expresses sex. Moreover, since the said barium dititanate single crystal has a high Curie point (about 470 degreeC), the application to the capacitor in a high temperature environment is expectable.

However, on the other hand, it can be said that barium dititanate is a material that is difficult to put into practical use because of its low relative dielectric constant (ε) at room temperature. In addition, as disclosed in Patent Document 1, barium dititanate has a characteristic of decomposing at 1150 ° C. or more and decomposing into BaTiO ₃ and Ba ₆ Ti ₁₇ O _{40, and is} put into practical use. From the point of view, various technical problems existed.

On the other hand, the present inventors surprisingly include the above composition formula (x = 0.20 to 0.50) containing barium titanate represented by the composition formula: BaTiO _3. It has been found that by obtaining the barium titanate-based composite oxide represented by 1), the above problems of barium dititanate (that is, problems of low insulation resistance and low relative dielectric constant) are solved. The present invention has been completed.

  In the barium titanate-based composite oxide represented by the composition formula (1) (sometimes referred to simply as “barium titanate-based composite oxide” or “composite oxide” in this specification), barium titanate When the content ratio (x) is 0.20 or more and 0.50 or less, the composition according to the present invention not only has excellent capacity-temperature characteristics in a range of −55 ° C. or more and 200 ° C. or less, but also has high insulation resistance. Indicates. Although the detailed mechanism is unknown, by including barium titanate with the above specific content ratio, the excellent capacity-temperature characteristic of barium dititanate at high temperature is maintained in the barium titanate-based composite oxide. However, it is presumed that the presence of barium titanate improves the insulation resistance and the relative dielectric constant.

  On the other hand, when the content ratio (x) of barium titanate is less than 0.20, the insulation resistance decreases. Moreover, the relative dielectric constant is also reduced. When the content ratio (x) of barium titanate exceeds 0.50, the influence of barium titanate having a low Curie point is increased, and excellent capacity-temperature characteristics derived from barium dititanate in a high-temperature environment. Is not demonstrated. Therefore, the capacity change rate at 200 ° C. cannot be within a range of ± 22%.

Moreover, the dielectric ceramic composition according to the present invention includes 0.5 mol% or more of SiO ₂ with respect to 100 mol% of the barium titanate-based composite oxide. Thus, by including SiO ₂ in a specific amount or more, it exhibits excellent capacity-temperature characteristics and insulation resistance without impairing the physical properties of the barium titanate-based composite oxide, and can be applied to ceramic electronic parts such as capacitors. A dielectric ceramic composition having excellent properties can be obtained. On the other hand, if the content of SiO ₂ is less than 0.5 mol%, the sinterability is poor (sintering density is low), and practical values for dielectric constant, dielectric loss and insulation resistance cannot be obtained, A dielectric ceramic composition applicable to ceramic electronic components cannot be obtained.

  Note that the mechanism for exerting the operational effects of the configuration of the present invention described above is speculation, and the present invention is not limited by the above speculation.

  Hereinafter, the dielectric ceramic composition of the present invention will be described in detail. Unless otherwise specified, measurements such as operation and physical properties are performed under conditions of room temperature (25 ° C.) / Relative humidity of 40% RH or more and 50% RH or less.

<Dielectric porcelain composition>
The dielectric ceramic composition of the present invention is a ceramic mainly composed of a barium titanate-based composite oxide represented by the composition formula (1). The definition of the term “consisting of the main component” is as described above, and a small amount of impure components that are included in the production may be included in the dielectric ceramic composition. Examples of impure components include metal-derived components such as sodium, calcium, niobium, iron, lead, hydrocarbon-based organic components, surface adsorbed water, and the like.

≪Main ingredient≫
The dielectric ceramic composition of the present invention contains, as a main component, a barium titanate-based composite oxide represented by a composition formula (1): xBaTiO _3. (1-x) BaTi ₂ O ₅ .

In the composition formula (1), “x” indicating the content ratio of barium titanate (BaTiO ₃ ) is 0.20 or more and 0.50 or less. For the purpose of obtaining a dielectric ceramic composition having good capacity-temperature characteristics at −55 ° C. or more and 200 ° C. or less and having a high insulation resistance value, the above “x” is more than 0.20 and less than 0.50. Preferably, it is 0.25 to 0.45, more preferably 0.30 to 0.40. On the other hand, “1-x” indicating the content ratio of barium dititanate (BaTi ₂ O ₅ ) is 0.50 or more and 0.80 or less. For the purpose of obtaining a dielectric ceramic composition having good capacity-temperature characteristics in a range of −55 ° C. or more and 200 ° C. or less and having a high insulation resistance value, the above “1-x” is more than 0.50 and 0 Is preferably less than .80, more preferably from 0.55 to 0.75, and particularly preferably from 0.60 to 0.70. The values of “x” and “1-x” can be obtained by XRD measurement, and more specifically, values obtained by the method (measurement conditions) described in the examples are adopted. The values of “x” and “1-x” can be controlled by the amount of barium titanate and barium dititanate added when the dielectric ceramic composition is manufactured.

≪Sub ingredients≫
The dielectric ceramic composition of the present invention contains SiO ₂ as a subcomponent. The dielectric ceramic composition of the present invention may further contain manganese oxide (MnO) and other components as required.

(Si oxide: SiO ₂ )
The dielectric ceramic composition of the present invention contains SiO ₂ (glass), and its content is 0.5 mol% or more with respect to 100 mol% of the barium titanate-based composite oxide. SiO ₂ (glass) is a component mainly added as a sintering aid. When SiO ₂ is contained in an amount of 0.5 mol% or more with respect to 100 mol% of the barium titanate composite oxide, a capacitor or the like is obtained without impairing the excellent capacity-temperature characteristics and insulation resistance of the barium titanate composite oxide. A dielectric ceramic composition excellent in applicability to ceramic electronic components can be obtained. Moreover, since the dielectric ceramic composition according to the present invention includes the specific amount of SiO ₂ , the dielectric ceramic composition has good sinterability, and is manufactured at a relatively low temperature such as 1250 ° C. or lower, further 1200 ° C. or lower. Firing is possible.

On the other hand, when the content of SiO ₂ is less than 0.5 mol%, the sinterability is lowered, and the application of the dielectric ceramic composition to the ceramic electronic component becomes difficult. On the other hand, the upper limit of the content of SiO ₂ is not particularly limited, but is preferably 10 mol% or less with respect to 100 mol% of the barium titanate-based composite oxide from the viewpoint of obtaining a practical relative dielectric constant. .

Furthermore, from the viewpoint of obtaining a dielectric ceramic composition having a practical dielectric constant while maintaining good sinterability, the content of SiO ₂ is 100 mol% of the barium titanate-based composite oxide. On the other hand, it is more preferably 1.0 mol% and less than 8.0 mol%, further preferably 1.3 mol% to 6.0 mol%, and more preferably 1.5 mol% to 5.0 mol%. Even more preferred is 2.0 mol% or more and 4.0 mol% or less. Note that the content of SiO _{2 in} the dielectric ceramic composition can be controlled by the amount of SiO ₂ added when the dielectric ceramic composition is manufactured.

(Mn oxide: MnO)
The dielectric ceramic composition of the present invention may contain other subcomponents other than those described above.

  Examples of other subcomponents include MnO. MnO is a component added mainly as a reduction resistance aid. The MnO content is not particularly limited, but is preferably 0.1 mol% or more with respect to 100 mol% of the barium titanate-based composite oxide. When MnO is contained in an amount of 0.1 mol% or more with respect to 100 mol% of the barium titanate-based composite oxide, oxygen vacancies generated in the firing step in a reducing atmosphere can be effectively suppressed. As a result, when a ceramic electronic component such as a capacitor is manufactured using the dielectric ceramic composition, the reliability of the ceramic electronic component is improved.

  On the other hand, the upper limit of the content of MnO is not particularly limited, but from the viewpoint of obtaining a dielectric ceramic composition having a good relative dielectric constant, it is 5. It is preferable in it being 0 mol% or less.

Furthermore, from the above viewpoint, the content of MnO is more preferably 0.15 mol% or more and 3.0 mol% or less, and 0.2 mol% or more and 2. mol% or more with respect to 100 mol% of the barium titanate composite oxide. 5 mol% or less is even more preferable, and 0.2 mol% or more and 2.0 mol% or less is particularly preferable. Note that the content of MnO in the dielectric ceramic composition is the manganese oxide added when the dielectric ceramic composition is manufactured (for example, MnO ₂ , Mn ₂ O ₃ , Mn ₃ O _4, etc.). ).

(Other minor ingredients)
The dielectric ceramic composition of the present invention may contain subcomponents other than those described above as long as the effects of the present invention are obtained. Examples of such subcomponents include barium compounds, magnesium compounds, calcium compounds, rare earth element compounds, and aluminum compounds. More specific compounds include, for example, barium compounds such as barium oxide (BaO), barium carbonate (BaCO ₃ ), and barium zirconate (BaZrO ₃ ); magnesium compounds such as magnesium oxide (MgO); calcium carbonate (CaCO ₃ ) Calcium compounds such as: dysprosium oxide (Dy ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), rare earth elements such as ytterbium oxide (Yb ₂ O ₃ ), aluminum compounds such as aluminum oxide (Al ₂ O ₃ ) Etc. Moreover, components other than the above, such as sintering aids and reduction resistance aids, may be further included.

≪Form and characteristics of dielectric ceramic composition≫
Although the form of the dielectric ceramic composition of the present invention is not limited, it can take the form of, for example, a sphere, a plate, a pellet, or a mixture thereof.

  The dielectric ceramic composition of the present invention is excellent in capacity-temperature characteristics, and exhibits a low capacity-temperature change rate in the range of −55 ° C. or more and 200 ° C. or less. The capacity temperature change rate (Tc) is defined by the following equation.

  The capacity temperature change rate (Tc) of the dielectric ceramic composition is preferably within ± 22% within a range of −55 ° C. or more and 200 ° C. or less. Furthermore, the capacity temperature change rate (Tc) is more preferably within ± 20%, and even more preferably within ± 15%. In the above formula, the capacitance at each temperature can be measured by the method described in the examples.

The dielectric ceramic composition of the present invention exhibits high insulation resistance. The insulation resistance value is preferably 1.00 × 10 ¹² Ω · cm or more, more preferably 5.00 × 10 ¹² Ω · cm or more, and particularly preferably 1.00 × 10 ¹³ Ω · cm or more. preferable. On the other hand, the upper limit is not particularly limited, but is substantially 1.0 × 10 ¹⁵ Ω · cm or less. The insulation resistance value can be measured by the method described in the examples.

  Furthermore, it is preferable that the dielectric ceramic composition of the present invention exhibits a high relative dielectric constant. The relative dielectric constant is preferably 100 or more, more preferably 150 or more, and particularly preferably 250 or more. On the other hand, the upper limit is not particularly limited, but is substantially 5000 or less. The relative dielectric constant can be measured by the method described in the examples.

  Furthermore, it is preferable that the dielectric ceramic composition of the present invention has a small dielectric loss. The dielectric loss is preferably 3.0% or less, more preferably 2.0% or less, even more preferably 1.8% or less, and particularly preferably 1.0% or less. On the other hand, the lower limit is not particularly limited, but is substantially 0.01% or more. The dielectric loss can be measured by the method described in the examples.

  The dielectric ceramic composition of the present invention having such characteristics can be obtained by the following production method. Hereinafter, a method for producing a dielectric ceramic composition will be described.

<Method for Producing Dielectric Porcelain Composition>
The dielectric ceramic composition of the present invention is not particularly limited as long as it has the above composition, and preferred methods include (1) a step of obtaining a molded body and (2) a method of undergoing a firing step. Hereinafter, each step will be described in detail.

(1) Step of obtaining a molded body In this step, (1-1) barium titanate, barium dititanate, SiO _2, and manganese oxide added as necessary are mixed to form a composition. And (1-2) a step of obtaining a molded body by molding using the obtained composition (green sheet production step).

(1-1) Composition Preparation Step In this step, barium titanate (BaTiO ₃ ), barium dititanate (BaTi ₂ O ₅ ), SiO _2, and an oxide of manganese added as necessary Are mixed to prepare a composition (slurry) for forming a green body (green sheet).

  At this time, the amount of barium titanate and barium dititanate is adjusted so that “x” in the composition formula (1) is within a predetermined range. That is, the molded body (green sheet) was adjusted so that the molar ratio (x: 1-x) of barium titanate to barium dititanate was in the range of 0.20: 0.80 to 0.50: 0.50. ) A composition (slurry) for preparation is prepared. The molar ratio of the barium titanate to barium dititanate is more preferably in the range of more than 0.2: less than 0.80 to less than 0.50: more than 0.50, and more preferably 0.25: 0. More preferably within the range of .75 to 0.45: 0.55, and particularly preferably within the range of 0.30: 0.70 to 0.40: 0.60. In the present specification, the description “from X to Y” refers to a range including the values of “X” and “Y”.

Further, the addition amount (total) of these barium titanate and barium dititanate is 100 mol%, and the SiO ₂ is added so as to be 0.5 mol% or more. That is, it is added so that SiO ₂ is 0.5 mol% or more with respect to 100 mol% of the barium titanate-based composite oxide produced by barium titanate and barium dititanate. Note that the preferable addition amount of SiO _{2 and} the addition amount of manganese oxide added as necessary can be calculated from the content (or preferable content) of each of the above-mentioned components, and therefore will be described in detail here. Will be omitted.

  The average particle diameter of barium titanate and barium dititanate used in this step is not particularly limited, but both are preferably 5000 nm or less, and more preferably 50 nm or more and 1000 nm or less. In addition, the value measured by the method of an Example is employ | adopted for the average particle diameter of each particle | grain.

  Furthermore, other subcomponents described above and additives such as a dispersant, a binder, and a plasticizer are mixed as necessary. These mixing methods and mixing order are not particularly limited, but wet mixing is preferable as the mixing method in that the additive can be uniformly dispersed.

As barium titanate and barium dititanate as raw materials, commercially available barium titanate powders may be used, and in addition to the solid phase method, various production methods (for example, oxalate method, hydrothermal synthesis method, alkoxide method) , A sol-gel method, etc.). The oxide of manganese is added as SiO ₂ and required like, for the auxiliary component may be used it may also be to synthetic a commercially available product. The dielectric ceramic composition according to the present invention does not require an expensive raw material such as niobium, can be produced from a relatively inexpensive raw material, and is very useful industrially.

  Below, the dispersing agent, binder, and plasticizer which can be contained in the composition for forming a green body (green sheet) will be described. In addition, the additive which can be contained in the said composition is not limited to the following, As long as the effect of this invention is not impaired, other additives, such as a lubricant and an antistatic agent, may be used.

  Although it does not restrict | limit especially as a dispersing agent which can be contained in a molded object (green sheet) preparation composition, For example, a phosphate ester type dispersing agent, a polycarboxylic acid type dispersing agent, etc. are mentioned. Among these, it is preferable to use a polycarboxylic acid dispersant. In addition, you may use the said dispersing agent individually or in combination of 2 or more types.

  The amount of the dispersant used is not particularly limited, but is preferably 0.1% by mass or more and 5% by mass or less with respect to the total mass (total mass) of the barium titanate, barium dititanate and subcomponents, More preferably, it is 0.3 mass% or more and 3 mass% or less, More preferably, it is 0.5 mass% or more and 1.5 mass% or less. By setting it within the above range, a sufficient effect as a dispersant can be obtained.

  Moreover, it does not restrict | limit especially as a binder which can be contained in a molded object (green sheet) preparation composition, For example, polyvinyl alcohol (PVA), polyvinyl butyral (PVB), an acrylic resin etc. are mentioned. In addition, the said binder may be used individually or in combination of 2 or more types.

  The amount of the binder used is not particularly limited, but is preferably 0.01% by mass or more and 20% by mass or less based on the total mass (total mass) of the barium titanate, barium dititanate, and accessory components. More preferably, it is 5 mass% or more and 15 mass% or less. By setting it as this range, the density of a molded object can be improved.

  Furthermore, the plasticizer that can be included in the molded article (green sheet) preparation composition is not particularly limited. For example, dioctyl phthalate, benzyl butyl phthalate, dibutyl phthalate, dihexyl phthalate, di (phthalate) ( Phthalic acid plasticizers such as 2-ethylhexyl) (DOP) and di (2-ethylbutyl) phthalate, adipic acid plasticizers such as dihexyl adipate and di (2-ethylhexyl) adipate (DOA), ethylene glycol, Glycol plasticizers such as diethylene glycol and triethylene glycol, glycol ester plasticizers such as triethylene glycol dibutyrate, triethylene glycol di (2-ethylbutyrate), triethylene glycol di (2-ethylhexanoate), etc. Is mentioned. Among these, when the composition is used as a green sheet, since the flexibility of the sheet is good, phthalic acid plasticizers such as dibutyl phthalate and di (2-ethylhexyl) phthalate (DOP) are used. It is preferable to use it. In addition, the said plasticizer may be used individually or in combination of 2 or more types.

  The amount of the plasticizer used is not particularly limited, but is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 50% by mass or less, based on the total mass of the binder to be added. It is particularly preferable that the content is not less than 40% by mass and not more than 40% by mass. By setting it within the above range, a sufficient effect as a plasticizer can be obtained.

  The solvent used in the case of wet mixing is not particularly limited. For example, water; alcohol solvents such as ethanol, methanol, benzyl alcohol, and methoxyethanol; glycol solvents such as ethylene glycol and diethylene glycol; acetone, methyl ethyl ketone, and methyl Ketone solvents such as isobutyl ketone and cyclohexanone; ester solvents such as butyl acetate, ethyl acetate, carbitol acetate, and butyl carbitol acetate; ether solvents such as methyl cellosolve, ethyl cellosolve, butyl ether, and tetrahydrofuran; benzene, toluene, xylene Aromatic solvents and the like. Later, considering the solubility and dispersibility of various additives contained in the composition, the solvent for the wet mixing is preferably an alcohol solvent or an aromatic solvent. Among these, it is preferable to use a low boiling point solvent such as methanol as the alcohol solvent and toluene as the aromatic solvent. In addition, the said solvent may be individual or may use 2 or more types together by arbitrary combinations and a ratio. When mixing two or more solvents, it is particularly preferable to mix the alcohol solvent and the aromatic solvent.

  The amount used in the case of using a solvent is preferably about 0.5 to 10 times the total mass (total mass) of barium titanate, barium titanate and subcomponents, and 0.7 to 5 times. It is more preferable that it is about twice or less. By setting the amount within the above range, barium titanate, barium titanate, subcomponents, and additives added as necessary can be sufficiently mixed, and the operation for removing the solvent can be easily performed later. it can.

  Moreover, when performing wet mixing, it is preferable to carry out by a wet ball mill, a wet bead mill, or a stirring mill. When zirconia balls are used in a wet ball mill, wet mixing is preferably performed using a large number of zirconia balls having a diameter of 0.1 mm to 10 mm, preferably 8 hours to 48 hours, more preferably 10 hours to 24 hours.

(1-2) Green Sheet Production Step In this step, the composition obtained in the step (1-1) is formed into a sheet having an appropriate size and shape, and a molded body (green sheet) is obtained. Make it. Here, it does not specifically limit as a method of producing a green sheet, A conventionally well-known method can be used. For example, a green sheet is obtained by forming into a sheet by a tape forming method such as a doctor blade method or a calender roll method, and drying the sheet.

  The thickness of the green sheet (thickness after drying) is not particularly limited, but is preferably 30 μm or less, and more preferably 20 μm or less. On the other hand, the lower limit of the thickness of the green sheet (thickness after drying) is not particularly limited, but is substantially 0.5 μm or more.

  Further, the obtained green sheets may be laminated until a desired thickness is obtained, and then thermocompression bonding may be performed. At this time, lamination is preferably performed until the total thickness (thickness after drying) is preferably about 0.1 mm to 5 mm, more preferably about 1 mm to 3 mm. Further, the conditions at the time of thermocompression bonding are not particularly limited, but the temperature is preferably about 50 to 150 ° C., the pressure is preferably about 10 to 200 MPa, and the pressurization time is about 1 to 30 minutes. Is preferable. Examples of the thermocompression bonding method include a warm isostatic pressing method (WIP).

  Thereafter, a green chip may be produced by cutting a laminate of green sheets into a desired chip shape.

  Furthermore, it is preferable to perform a so-called degreasing process, in which a binder component or the like contained in the obtained green sheet (or green chip) is thermally decomposed and removed. The degreasing conditions are not particularly limited and depend on the type of binder used, but are preferably 180 ° C. or higher and 450 ° C. or lower. The degreasing time is not particularly limited, but is preferably 0.5 hours or more and 24 hours or less. Furthermore, the degreasing treatment can be performed in air or in an inert gas such as nitrogen or argon, but it is preferably performed in air from the viewpoint of ease of operation.

(2) Firing step In this step, the green sheet (or green chip) obtained in the step (1-2) is fired.

The firing temperature in this step is not particularly limited as long as the dielectric ceramic composition can be obtained, but is preferably 1250 ° C. or lower. That is, in the second embodiment of the present invention, after mixing barium titanate represented by BaTiO ₃ , barium titanate represented by BaTi ₂ O ₅ , and a glass component represented by SiO _2. A method for producing a dielectric ceramic composition, comprising: forming a molded body to obtain a molded body; and firing the molded body at a temperature of 1250 ° C. or less, wherein the barium titanate and the barium dititanate The molar ratio is 0.20: 0.80 to 0.50: 0.50, and the added amount of SiO ₂ with respect to a total of 100 mol% of the barium titanate and the barium dititanate Is a method for producing a dielectric ceramic composition, which is 0.5 mol% or more.

  Thus, in the production process of the dielectric ceramic composition, it is preferable to set the firing temperature to a relatively low temperature of 1250 ° C. or lower. Thus, by setting the firing temperature to 1250 ° C. or less, decomposition of barium dititanate and barium titanate and barium dititanate from becoming a solid solution are suppressed.

Furthermore, for the purpose of suppressing decomposition of barium dititanate and solid solution formation between barium titanate and barium titanate, the firing temperature is more preferably 1200 ° C. or less, and particularly preferably 1180 ° C. or less. As described above, it is known that barium dititanate decomposes at 1150 ° C. or higher. However, the present inventors set the firing temperature to 1150 in the production process of the dielectric ceramic composition according to the present invention. It has also been found that barium dititanate does not decompose even when the temperature is higher than ° C. The mechanism by which such an effect of suppressing the decomposition of barium dititanate is obtained is unknown, but in the above compositional formula (1), the effect of setting the value of “x” to 0.20 or more and 0.50 or less. Presumed to be. Conventionally, it has been difficult to effectively utilize characteristics such as capacity-temperature characteristics of barium dititanate. However, according to the present invention, decomposition of barium dititanate is suppressed by the presence of barium titanate. The excellent capacity-temperature characteristics of barium titanate at high temperatures can be effectively utilized.

  On the other hand, the lower limit of the firing temperature is not particularly limited as long as a sintered body can be obtained, but is preferably 1000 ° C. or higher and more preferably 1150 ° C. or higher.

  The firing time is not particularly limited, but is preferably 1 hour or longer and 5 hours or shorter, and more preferably 1 hour or longer and 3 hours or shorter. The firing atmosphere is not particularly limited, and examples thereof include an air atmosphere, an inert gas atmosphere such as nitrogen and argon, or a reducing atmosphere in which hydrogen, water vapor, or the like is mixed with nitrogen or argon.

  As other firing conditions, the heating rate is preferably 50 ° C./hour or more and 500 ° C./hour or less, more preferably 200 ° C./hour or more and 300 ° C./hour or less.

<Ceramic electronic parts>
A third aspect of the present invention is a ceramic electronic component including the dielectric ceramic composition or the dielectric ceramic composition obtained by the manufacturing method. The dielectric ceramic composition of the present invention or the dielectric ceramic composition obtained by the production method of the present invention can be suitably used for various ceramic electronic components. Hereinafter, a multilayer ceramic capacitor, which is an example of a ceramic electronic component, will be described.

(Multilayer ceramic capacitor)
A dielectric ceramic composition obtained by firing a green sheet (or green chip) has a thin film shape and can be used as a dielectric layer of a multilayer ceramic capacitor (MLCC). Although it does not restrict | limit especially as a manufacturing method of a multilayer ceramic capacitor, For example, it manufactures as follows.

  First, an internal electrode conductive paste containing various metals or the like is screen-printed in a predetermined shape on the green sheet to form an internal electrode conductive paste film. The material for the internal electrode is not particularly limited, and examples thereof include a metal such as Cu, Ni, W, Mo, Ag, or an alloy thereof.

  The material of the external electrode is not particularly limited, and examples thereof include metals such as Cu, Ni, W, Mo, and Ag or alloys thereof; alloys such as In—Ga and Ag-10Pd; carbon, graphite, and carbon and graphite. What consists of a mixture etc. are mentioned.

  Then, after laminating a plurality of green sheets on which the internal electrode conductive paste film is formed, and laminating and crimping the green sheets on which the conductive paste film is not formed so as to sandwich the green sheets, A laminated body (green chip) is obtained by cutting as necessary.

  And after performing a binder removal process to the obtained laminated body (green chip), the said green chip is baked in inert gas atmosphere or reducing atmosphere, and a capacitor chip body is obtained. In the capacitor chip body, dielectric layers made of a sintered body obtained by firing green sheets and internal electrodes are alternately laminated. What is necessary is just to employ | adopt suitably the conditions shown by said (2) baking process as baking conditions.

  When firing is performed in a reducing atmosphere, it is preferable to anneal the obtained capacitor chip body in order to reoxidize the dielectric layer.

  Next, an external electrode paste containing the above various metals on the end face of the capacitor chip body so that the external electrode is electrically connected to each edge of the internal electrode exposed from the end face of the capacitor chip body. The external electrode is formed by coating. Then, if necessary, a coating layer is formed on the external electrode surface by plating or the like. In this way, a multilayer ceramic capacitor can be manufactured.

  Although the multilayer ceramic capacitor has been described as an example of the ceramic electronic component, the ceramic electronic component according to the present invention is not limited to this. For example, various other components such as a high-frequency module, an electronic component for the thermistor, or a composite component thereof may be used.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

<Preparation of dielectric ceramic composition>
The following materials were used.

The barium titanate and barium dititanate were prepared using titanium oxide (TiO ₂ Super Titania (registered trademark): F-2, Showa Denko KK) and barium carbonate (BaCO ₃ BW-KH30, Sakai Chemical Industry). Used). When producing barium titanate with respect to 1 mol of barium carbonate, 1 mol of titanium oxide was added, and when producing barium dititanate, 2 mol of titanium oxide was added and mixed well. Thereafter, barium titanate and barium dititanate were respectively obtained by heat treatment (calcination) at 900 ° C. for 3 hours.

  In the above, the “average particle size” is obtained by taking an image with a scanning electron microscope, extracting 50 particles at random, measuring the particle size, and averaging the results. Moreover, when the shape of particle | grains is not spherical, it defines as what was calculated by measuring a major axis.

<< Examples 1 to 10, Comparative Examples 1 to 4 >>
Each raw material of barium titanate (BaTiO ₃ ), barium dititanate (BaTi ₂ O ₅ ), SiO _2, and Mn ₃ O ₄ was weighed using an electronic balance so as to have the composition ratio shown in Table 1 below. In Table 1 below, the ratio (mol%) of SiO ₂ and MnO is a value when the total of barium titanate and barium dititanate is 100 mol%, respectively. Further, the amount of Mn ₃ O ₄ added was measured so as to be the ratio of MnO in Table 1 below.

A mixed solvent of ethanol / toluene (60/40 mass ratio) was used so that the solid content was 50% by mass, and 3 mmφ ZrO ₂ balls were used. Went for hours. Thereafter, a binder (PVB, manufactured by Sekisui Chemical Co., Ltd., BH-3) solution (PVB solid content 15% by mass, solvent: ethanol / toluene = 60/40 mass ratio), PVB / total of each raw material = 10/90 Add to a mass ratio, and add di (2-ethylhexyl) phthalate (DOP) to 35% by mass with respect to the binder (PVB) and mix at 25 ° C. for 4 hours on a rotating ball mill stand. The ceramic slurry was obtained.

  Using the obtained ceramic slurry, a sheet was formed on a PET film by a doctor blade method using a 350 μm gap applicator. 50 layers of the obtained green sheets (thickness: about 20 μm) are laminated and heat press molding is performed (pressurization temperature: 80 ° C., pressurization pressure: 90 MPa, pressurization time: 3 minutes), cut into 1 cm square. The binder removal treatment was performed under the conditions of 400 ° C. × 2 hours. Thereafter, firing was performed at each firing temperature shown in Table 1 (in a mixed atmosphere of 1% by volume hydrogen and 99% by volume nitrogen, firing time: 2 hours) to obtain a dielectric ceramic composition.

<Evaluation>
The dielectric ceramic compositions obtained in the above examples and comparative examples were evaluated as follows.

≪XRD measurement≫
Each dielectric ceramic composition was subjected to XRD measurement (measurement was performed using an X-ray diffractometer (manufactured by PANalytical, RAYONS X, the radiation source being Cu-Kα, voltage 45 kV, current 40 mA). As a result, it was confirmed that the content ratio of each component in the obtained dielectric magnetic composition was the same as the addition amount (ratio) of each component described in Table 1 (except for Comparative Example 1). The values of “x” and “1-x” in the obtained dielectric magnetic composition are values obtained from the XRD measurement results. BaTiO ₃ is a space group: P4 mm, and BaTi ₂ O ₅ is Space group: A value obtained by Rietveld analysis using A / 12m1, unique-b.

  In Comparative Example 1, barium titanate and barium dititanate reacted to generate a third component (the component is unknown).

≪Relative permittivity and dielectric loss≫
An indium-gallium (In-Ga) alloy is applied to the upper and lower surfaces of each dielectric ceramic composition as an electrode, and an LCR meter (4284A manufactured by Agilent, Inc., measurement conditions: AC applied voltage 1.0 V / mm, frequency 1 kHz) is used. The relative dielectric constant and dielectric loss were measured.

≪Insulation resistance (IR) ≫
A high resistance meter 4339B manufactured by Agilent Technologies, Inc. was used, and measurement was performed with an applied voltage DC: 250 V and an application time of 60 seconds.

≪Capacitance temperature characteristics≫
The capacitance-temperature characteristics were obtained by measuring the capacitance in the temperature range from −55 ° C. to 200 ° C. with respect to the dielectric ceramic compositions of Examples and Comparative Examples. The capacitance was measured by using a digital LCR meter (manufactured by Hewlett-Packard Japan, 4274A) under the conditions of a frequency of 1 kHz and an input signal level of 1 Vrms. And the electrostatic capacitance in the temperature environment from -55 degreeC to 200 degreeC is measured, and the change rate (unit:%) of the electrostatic capacitance in each temperature with respect to the electrostatic capacitance in 25 degreeC is calculated according to the following formula. Then, the capacity change rate (Tc) at each temperature was examined. At this time, if both Tc = ± 22% at both −55 ° C. and 200 ° C., it is determined to be acceptable (described as “◯” in Table 1 below).

The firing temperatures and evaluation results of the dielectric ceramic compositions of the examples and comparative examples are shown in Table 1 below. In the column of “capacitance-temperature characteristics” in Table 1 below, as a result of the measurement of the capacity-temperature characteristics, “within Tc = ± 22% at both −55 ° C. and 200 ° C.” Those that do not have a cross. Moreover, in the column of “overall judgment”, the case where the insulation resistance is 1.0 × 10 ¹² Ω · cm or more and satisfies the above capacity-temperature characteristics is indicated as “◯”, and the case where any one of them is not satisfied is × It was.

  In addition, the capacity change rates at each temperature were plotted for the dielectric ceramic compositions of Examples 2 and 3 and Comparative Examples 1 and 3. FIG. 1 shows the results of Examples 2 and 3, and FIG. 2 shows the results of Comparative Examples 1 and 3. In FIGS. 1 and 2, the range indicated by a square frame represented by a two-dot chain line in the graph is a range from −55 ° C. to 200 ° C. and a capacity change rate (Tc) = ± 22%. .

  From the results shown in Table 1 and FIG. 1, the dielectric ceramic compositions of the examples showed not only excellent capacity-temperature characteristics at −55 ° C. and 200 ° C., but also high insulation resistance. Although FIG. 1 shows the results of Examples 2 and 3, in the other examples as well, the capacity change rate (Tc) is within a range of ± 22% from −55 ° C. to 200 ° C. Yes, it was confirmed to show good capacity-temperature characteristics. In particular, Examples 1 to 3, 5 and 7 to 9 have a capacity change rate (Tc) in the range of ± 15% from −55 ° C. to 200 ° C., satisfy the R standard, and have very high temperature characteristics. It was confirmed to be excellent.

  On the other hand, the dielectric ceramic composition of Comparative Example 1 has a small amount of barium titanate. From Table 1 and FIG. 2, the dielectric ceramic composition of Comparative Example 1 showed the result that the capacitance-temperature characteristics were good, but the insulation resistance was low. Such a decrease in the insulation resistance value is presumed to be caused by an increase in dielectric loss due to the reaction between barium titanate and barium dititanate and the generation of the third component. Moreover, although the dielectric ceramic compositions of Comparative Examples 2 and 3 have a high barium titanate content, the capacity-temperature characteristics at high temperatures (200 ° C.) were reduced. This is presumed that, in Comparative Examples 2 and 3, the content of barium titanate is large, so that the capacity-temperature characteristic was lowered at a temperature exceeding the Curie point (200 ° C.).

Moreover, even if the dielectric ceramic composition of Comparative Example 4 having a high SiO ₂ (glass) content is fired at 1250 ° C., it cannot be fired sufficiently and a sintered body cannot be obtained. It was.

Claims (5)

A composite oxide represented by a composition formula (1): xBaTiO _3. (1-x) BaTi ₂ O ₅ (wherein x in the composition formula (1) is 0.20 or more and 0.50 or less). Including as a main component,
The composite oxide with respect to 100 mol%, containing 0.5 mol% or more of SiO _2, the dielectric ceramic composition.   The dielectric ceramic composition according to claim 1, further comprising 0.1 mol% or more of MnO with respect to 100 mol% of the composite oxide.   A ceramic electronic component comprising the dielectric ceramic composition according to claim 1. Barium titanate represented by BaTiO ₃ ;
Barium dititanate represented by BaTi ₂ O ₅ ;
A glass component represented by SiO ₂ ;
And then molding to obtain a molded body,
Firing the molded body at a temperature of 1250 ° C. or lower, and a method for producing a dielectric ceramic composition,
The molar ratio of the barium titanate to the barium dititanate ranges from 0.20: 0.80 to 0.50: 0.50,
The method for producing a dielectric ceramic composition, wherein the added amount of SiO ₂ is 0.5 mol% or more with respect to 100 mol% in total of the barium titanate and the barium dititanate.   In the step of obtaining the molded body, manganese oxide is further added so as to be 0.1 mol% or more in terms of MnO with respect to 100 mol% in total of the barium titanate and barium dititanate. The manufacturing method of the dielectric material ceramic composition of Claim 4 containing.