JP2005225721A - Production method for dielectric powder and production method for composite dielectric material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a fine dielectric powder suppressed in degradation of dielectric properties while using a solid phase method. <P>SOLUTION: The production method, for producing a dielectric powder containing a perovskite oxide having an atomic arrangement of an ABO<SB>3</SB>type, has a step of yielding a mixture containing an A site raw material powder for constituting an A site and a B site raw material powder having a BET value of 20 m<SP>2</SP>/g or higher and for constituting a B site, a first firing step of firing the mixture to yield a first fired product, and a first grinding step of grinding the first fired product to yield a first powder. Since the first powder is prepared by using the B site raw material powder having a BET value of 20 m<SP>2</SP>/g or higher, it can be made fine, specifically so as to have a D50 (diameters of particles of which the cumulative number is 50%) of 1 μm or less, moreover 0.8 μm or less, without passing through long-time grinding. A composite dielectric material composed of the dielectric powder and a resin has excellent dielectric properties. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a dielectric powder, and more particularly, to a dielectric powder manufacturing method and a composite dielectric material manufacturing method capable of obtaining a high dielectric property by forming a composite dielectric material together with a resin.

In recent years, miniaturization, weight reduction, and speeding up of communication devices have been strongly desired. Among them, the frequency band of radio waves used for portable mobile communications such as digital cellular phones and satellite communications is in the high frequency band of mega to giga Hz band (referred to as “GHz band”). Amid the rapid development of used communication equipment, the housing, board, and electronic elements have been miniaturized and densely mounted. However, the communication equipment that supports the high frequency band has been further reduced in size and weight. In order to achieve this, materials such as substrates used in communication equipment must be excellent in high-frequency transmission characteristics (low dielectric loss) in the GHz band. Here, the dielectric loss is proportional to the product of the frequency, the relative dielectric constant εr of the substrate, and the dielectric loss tangent (hereinafter referred to as tan δ). Therefore, in order to reduce the dielectric loss, tan δ of the substrate must be reduced. Further, since the wavelength of the electromagnetic wave in the substrate is shortened to 1 / (εr) ^0.5 , the substrate can be downsized as the relative dielectric constant εr increases. As described above, a circuit board used for a small communication device, electronic device, or information device used in a high frequency band has a high relative dielectric constant εr and Qf (quality factor Q = 1 / tan δ, f = resonance frequency). Is required to be large.

  As such a circuit board material, a dielectric material (fired body) as an inorganic material, a fluororesin as an organic material, or the like is used. However, a substrate made of a dielectric material has problems in dimensional accuracy and workability, and is fragile, so that there is a problem that chips and cracks are likely to occur. On the other hand, a substrate made of an organic material such as a resin has the advantage of being excellent in moldability and workability, but has a problem that the relative dielectric constant εr is small. Therefore, in recent years, as a substrate having both advantages, for example, a composite substrate made of a dielectric powder and a resin material in Patent Document 1 (Japanese Patent Laid-Open No. 2003-128930) and Patent Document 2 (Japanese Patent Laid-Open No. 2003-151352). Is disclosed.

As the dielectric material, a perovskite oxide having an ABO ₃ type atomic arrangement such as barium titanate and lead zirconate titanate is usually used, and a method for producing the powder (dielectric powder) is a liquid phase. Methods, gas phase methods, flux methods and solid phase methods are known.
In the liquid phase method, a metal oxide precursor powder such as a hydrate is produced using a metal salt aqueous solution or an organic solvent solution as a starting material, and then the precursor powder is fired to contain two or more kinds of metal elements. This is a method for producing a metal oxide powder. As the liquid phase method, a precipitation method, a coprecipitation method, a hydrolysis method and the like are known.
The gas phase method is a method for producing a metal oxide powder by a chemical reaction of a metal vapor or a metal compound in a gas phase state, and has an advantage that a powder having a narrow particle size distribution and less aggregation is obtained.
The flux method is a method for producing a metal oxide powder by adding a flux component to a metal oxide mixed powder and firing it.

JP 2003-128930 A Japanese Patent Laid-Open No. 2003-151352

  The dielectric powder obtained by the above liquid phase method, gas phase method and flux method has the advantage that the particle size can be made fine and the particle size distribution can be narrowed. Here, when the composite substrate described above is manufactured, it is desirable that the dielectric powder mixed with the resin material has a small particle diameter when the interlayer when the composite substrate is laminated is thinned. Since the dielectric powder obtained by the liquid phase method, the gas phase method and the flux method has a fine particle size, it is a desirable method for producing a dielectric powder in producing a composite substrate. However, there is a problem that the cost of the dielectric powder obtained by these methods is high.

A solid phase method is known as a method for obtaining dielectric powder at a lower cost than the above methods. The solid phase method includes a step of firing a powder such as a metal oxide or carbonate at a high temperature and pulverizing the obtained fired product. For example, when obtaining barium titanate, TiO ₂ powder and BaCO ₃ powder are mixed and fired as raw material powder, and the fired product obtained is pulverized. In this pulverization process, distortion occurs in the pulverized powder, which deteriorates the dielectric characteristics. In particular, in order to obtain a powder having a small particle diameter by pulverization, it is necessary to lengthen the pulverization time or to make the pulverization conditions strict, and the dielectric characteristics of the fine dielectric powder are significantly deteriorated. If the pulverization time is shortened in order not to deteriorate the dielectric characteristics, it is impossible to obtain a fine dielectric powder. Therefore, until now, there has been a problem that a composite substrate using a dielectric powder by a solid phase method cannot obtain desired characteristics. On the other hand, if a fine powder with little deterioration in dielectric properties can be obtained by the solid phase method, it becomes a very desirable method for producing a dielectric powder in order to obtain a composite substrate, considering the cost.

  In view of the above background, an object of the present invention is to provide a method for producing a fine dielectric powder in which deterioration of dielectric properties is suppressed while using a solid phase method. Another object of the present invention is to provide a method for producing a composite dielectric material composed of a dielectric powder and a resin material, using such a dielectric powder and having excellent dielectric characteristics.

A dielectric material containing a perovskite oxide having an ABO ₃ type atomic arrangement targeted by the present invention is obtained by mixing and firing an A site material for forming the A site and a B site material for forming the B site. Can be obtained. For example, in order to obtain (Sr, Ca) TiO ₃ , SrCO ₃ powder and CaCO ₃ powder are usually prepared as the A site material, and TiO ₂ powder is prepared as the B site material. According to the study by the present inventors, it has been found that by controlling the BET value of the B site raw material to a specific value, a sufficiently fine powder can be obtained even if the pulverization after firing is light. And it was confirmed that the composite dielectric material using this powder has excellent dielectric properties.

The present invention is based on the above knowledge, and is a method for producing a dielectric powder containing a perovskite oxide having an ABO ₃ type atomic arrangement, which comprises an A site raw material powder that constitutes the A site and a B site. A step of obtaining a mixture containing a B-site raw material powder having a specific surface area (value according to the BET method, simply referred to as BET value in the present invention) of 20 m ² / g, and a first firing product obtained by firing the mixture And a first pulverizing step of pulverizing the first baked product to obtain a first powder. Since the first powder according to the present invention uses the B-site raw material powder having a BET value of 20 m ² / g or more, it is fine, specifically, 1 μm or less, and without being pulverized for a long time. The D50 can be 0.8 μm or less (the particle diameter of the particles with a cumulative number of 50%). Since the first powder does not need to be pulverized for a long time, the distortion due to the pulverization is small and excellent dielectric properties can be exhibited.
The present invention includes a second firing step for obtaining a second fired product by subjecting the first powder obtained in the first grinding step to a predetermined treatment, and a second powder obtained by grinding the second fired product. Obtaining a second grinding step. Similarly to the first powder, this second powder can be made fine with a D50 of 1 μm or less without being pulverized for a long time. The predetermined treatment is a concept including adding and mixing various subcomponents. However, this subcomponent can also be added before the first firing step.

  In the dielectric powder according to the present invention, the A site contains one or more atoms selected from Ba, Ca and Sr, and the B site is selected from one or more selected from Ti, Zr and Nb. From the viewpoint of dielectric properties, it is desirable to contain the above atoms.

The dielectric powder according to the present invention can be used for the production of a composite dielectric material including a dielectric powder made of a perovskite oxide having an ABO ₃ type atomic arrangement and a resin. That is, according to the present invention, a dielectric powder is obtained by pulverizing a fired product made from A site raw material powder constituting A site and B site raw material powder having BET value of 20 to 40 m ² / g constituting B site. There is provided a method for producing a composite dielectric material comprising a step and a step of combining the dielectric powder and a resin.
The method for producing a composite dielectric material of the present invention uses a dielectric powder obtained by pulverizing a fired product based on a B-site raw material powder having a BET value of 20 to 40 m ² / g. The dielectric properties of the material are good.
Here, the fired product made from the A site raw material powder and the B site raw material powder having a BET value of 20 to 40 m ² / g includes both the first fired product and the second fired product. . The dielectric powder includes both the first powder and the second powder.

  Also in the method for producing a composite dielectric material according to the present invention, the A site contains one or more atoms selected from Ba, Ca and Sr, and the B site is selected from Ti, Zr and Nb. Or it is desirable to contain 2 or more types of atoms.

  As described above, according to the present invention, a fine dielectric powder can be obtained without pulverizing for a long time. Therefore, a composite dielectric material having low cost and excellent dielectric characteristics can be obtained.

The dielectric material to which the present invention is applied is a perovskite oxide having an ABO ₃ type atomic arrangement. Here, the A site contains one or more atoms selected from Ba, Ca and Sr, and the B site contains one or more atoms selected from Ti, Zr and Nb. Is desirable. Therefore, the present invention is desirably applied to at least the following perovskite oxides.
SrTiO ₃ , CaTiO ₃ , (Sr, Ca) TiO ₃ , (Sr, Ba) TiO ₃ , (Ca, Ba) TiO ₃ , (Ba, Sr, Ca) TiO ₃
SrZrO ₃ , CaZrO ₃ , (Sr, Ca) ZrO ₃ , (Sr, Ba) ZrO ₃ , (Ca, Ba) ZrO ₃ , (Ba, Sr, Ca) ZrO ₃
SrNbO ₃ , CaNbO ₃ , (Sr, Ca) NbO ₃ , (Sr, Ba) NbO ₃ , (Ca, Ba) NbO ₃ , (Ba, Sr, Ca) NbO ₃
Sr (Ti, Zr) O ₃ , Ca (Ti, Nb) O ₃ , (Sr, Ca) (Zr, Nb) O ₃ , (Sr, Ba) (Ti, Zr, Nb) O ₃

The dielectric material to which the present invention is applied is based on the perovskite oxide described above, and can further contain various subcomponents. In the present invention, an oxide of A (where A is one or two elements selected from Ni, Mn and Cr) can be added as a subcomponent. In addition, an oxide of X (where X is one or more elements selected from V, Nb, W, Ta, and Mo) can be added as a subcomponent. Further, R (where R is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu are selected from one or two kinds Oxides of the above elements) can be added. Furthermore, SiO ₂ , MO (where M is one or more elements selected from Ba, Ca, Sr and Mg), Li ₂ O, B ₂ O ₃ and one kind selected from MSiO _3. Alternatively, two or more compounds can be added.

The present invention is a method for producing a dielectric powder made of the perovskite oxide having the ABO ₃ type atomic arrangement described above. By the way, the dielectric material made of a fired body includes, for example, a step of mixing raw material powders weighed so as to have a final composition, a step of calcining the mixed powder, a step of grinding the calcined product, and a step of firing the ground powder. It can manufacture by passing. In this manufacturing method, the dielectric powder can be obtained by pulverizing the above-mentioned calcined product, and can also be obtained by pulverizing the fired body obtained through the firing step. When the former mode is the first mode and the latter mode is the second mode, the method for producing a dielectric powder in the present invention can be applied to either the first mode or the second mode. The effect of controlling the particle size of the powder in the present invention is embodied in the first aspect, that is, the pulverized powder after calcining, and also in the second aspect, that is, the powder obtained by pulverizing the fired body. . In the case of the first aspect, since the baking is not performed after the step usually referred to as calcination, in the present invention, this is referred to as the first calcination instead of calcination, and in the second aspect, The firing performed after the first firing is referred to as the second firing.

First, the first aspect will be described.
As the raw material for obtaining the dielectric powder of the present invention, a raw material constituting the main component and a raw material constituting the subcomponent are prepared. However, although the addition of subcomponents is desirable, it is not essential in the present invention.
As the raw material constituting the main component, an A site raw material powder for constituting the A site and a B site raw material powder for constituting the B site are prepared. As the A-site raw material powder and the B-site raw material powder, an oxide of the element and / or a compound that becomes an oxide by firing is used. Examples of the compounds that become oxides upon firing include carbonates, nitrates, oxalates, and organometallic compounds. These compounds and oxides may be used in combination. Specifically, as the A-site raw material powder, it is desirable to use one or more selected from SrCO ₃ powder, CaCO ₃ powder and BaCO ₃ powder. As the B-site material powder, TiO ₂ powder, to use one or two or more kinds selected from ZrO ₂ powder and NbO ₂ powder desirable.

The present invention is characterized in that a B-site raw material powder having a specific surface area (value according to BET method, hereinafter simply referred to as BET value) of 20 m ² / g or more is used. As shown in the examples described later, when the BET raw material powder has a BET value of 20 m ² / g or more, a fine dielectric having a D50 of 1 μm or less without pulverization for a long time after the first firing. This is because body powder can be obtained. Since it is not necessary to grind for a long time, the dielectric characteristics of the dielectric powder obtained by the present invention are good. As a result, the dielectric characteristics of the composite dielectric material using this dielectric powder are also good.
On the other hand, in the present invention, the A-site raw material powder does not need to specify the BET value unlike the B-site raw material powder. According to the study by the present inventor, the BET value of the A-site raw material powder does not affect the particle size of the obtained dielectric powder. Therefore, for the A-site raw material, D50 may be appropriately selected within the range of 0.01 to 5.0 μm.

The subcomponent raw materials constituting the subcomponent are as follows.
As for the oxide of A, the oxide of A and / or a compound that becomes an oxide of A upon firing can be used as a raw material.
As for the oxide of X, one or more single oxides or composite oxides selected from the oxide of X and / or the compound that becomes an oxide of X by firing can be used as a raw material.
As for the R oxide, one or more single oxides or composite oxides selected from R oxides and / or compounds that become oxides upon firing can be used as raw materials.
SiO ₂ , MO (where M is one or more elements selected from Ba, Ca, Sr and Mg), one or two selected from Li ₂ O, B ₂ O ₃ and MSiO ₃ About the seeds or more, the compound can be used as a raw material.
The auxiliary component raw material powder may also be appropriately selected within a range of D50 from 0.01 to 5.0 μm.

The raw material powders of the above main component and subcomponent are weighed according to a desired composition and wet-mixed by, for example, a ball mill. After this slurry is dried, first baking is performed, for example, in the range of 900 to 1350 ° C. for a predetermined time. The atmosphere at this time may be N ₂ or O ₂ or a mixed gas thereof. What is necessary is just to select the holding time of 1st baking suitably in the range of 0.5 to 5.0 hours.

The first fired product obtained by the first firing is pulverized. A ball mill or other pulverizing means can be used for the pulverization. When wet pulverization is performed, drying is performed after pulverization. According to the present invention, by setting the BET value of the B-site raw material powder to 20 m ² / g or more, D50 is 1 μm or less, further 0.8 μm or less while suppressing distortion due to short grinding time, in other words, distortion due to grinding. It is possible to obtain a fine dielectric powder. This pulverization may be performed under the same conditions as when the main component material and the subcomponent material are mixed.

Next, the second aspect includes an aspect in which the auxiliary component is added before the first baking and an aspect in which the auxiliary component is added after the first baking. Here, an aspect in which the auxiliary component is added after the first baking will be described. .
The second aspect is carried out until the first firing and pulverization in the same manner as the first aspect described above, except that the subcomponent is not weighed and mixed with the main component. After this pulverization, the auxiliary component raw material is added to and mixed with the powder composed of the main component obtained by pulverization. This mixing may be performed in the same manner as the mixing of the main component material and the subcomponent material in the first embodiment.
The powder obtained by mixing is subjected to second firing. The second baking may be performed under the same conditions as the first baking described above.
The fired product obtained by the second firing is pulverized. This pulverization may be performed under the same conditions as the pulverization performed in the first aspect.
Similarly to the powder obtained in the first aspect, the powder obtained by the above steps also has a fine particle size by relatively short pulverization.

  The composite dielectric material of the present invention preferably conforms to the following manufacturing method. First, a predetermined amount of dielectric powder and organic polymer resin are prepared and mixed. In addition, although mixing can also be performed by dry mixing, for example, it is desirable to sufficiently mix in an organic solvent such as toluene and xylene with a ball mill, a stirrer, or the like. This slurry is dried at 90 to 120 ° C. to obtain a mass of dielectric powder and organic polymer resin. This lump is pulverized to obtain a mixed powder of dielectric powder and organic polymer resin. A granule manufacturing apparatus such as a spray dryer may be used as a method of making a mixed powder from the slurry. The average particle size of the mixed powder may be about 50 to 1000 μm. Next, this mixed powder is press-molded into a desired shape at 100 to 200 ° C., and the molded product is cured at a temperature of 100 to 200 ° C. In this curing, a reinforcing material described later may be present.

  In the composite dielectric material according to the present invention, when the total of the dielectric powder and the resin is 100 vol%, the content of the dielectric powder is 30 to 70 vol%. When the amount of the dielectric powder is less than 30 vol% (the amount of resin exceeds 70 vol%), the dimensional stability as a substrate is lacking and the dielectric constant ε is lowered. That is, the effect of containing dielectric powder is not so much seen. On the other hand, when the amount of the dielectric powder exceeds 70 vol% (the amount of the resin is less than 30 vol%), the fluidity becomes very poor during press molding, and a dense molded product cannot be obtained. As a result, water or the like can easily enter, leading to deterioration of electrical characteristics. Further, the Q value may be greatly reduced as compared with the case where no dielectric powder is added. Therefore, the content of the dielectric powder is set to 30 to 70 vol%. A desirable dielectric powder content is 40 to 65 vol%, and a more desirable dielectric powder content is 45 to 60 vol%. However, the optimum content of the dielectric powder varies depending on the shape of the substrate pattern. When the shape of the substrate pattern is relatively fine, the desirable content of the dielectric powder is 35 to 50 vol. %.

  Resins used for the composite dielectric material of the present invention include unsaturated polyester resins, vinyl ester resins, polyimide resins, bismaleimide triazine (cyanate ester) resins, polyphenylene ether (oxide) resins, fumarate resins, polybutadiene resins, vinyls. Any one or more thermosetting resins among benzyl resins can be used. Alternatively, it is possible to use at least one thermoplastic resin among aromatic polyester resin, polyphenylene sulfide resin, polyethylene terephthalate resin, polyethylene sulfide resin, polyethyl ether ketone resin, polytetrafluoroethylene resin, polyarylate resin, and graft resin. it can. Furthermore, a resin in which at least one of the thermosetting resins and at least one of the thermoplastic resins are combined can also be used.

  A reinforcing material can be added to the resin in the present invention. The reinforcing material is effective in improving the mechanical strength and dimensional stability, and a predetermined amount of reinforcing material is usually added to the resin when the circuit board is manufactured. Examples of the reinforcing material include non-fibrous reinforcing materials such as a fibrous shape, a plate shape, and a granular shape. Examples of fibrous reinforcing materials include glass fiber, alumina fiber, aluminum borate fiber, ceramic fiber, silicon carbide fiber, asbestos fiber, gypsum fiber, brass fiber, stainless steel fiber, steel fiber, metal fiber, magnesium borate whisker or its fiber And inorganic fibers such as potassium titanate whisker or its fiber, zinc oxide whisker and boron whisker fiber, carbon fiber, aromatic polyamide fiber, aramid fiber, polyimide fiber and the like. In the case where a fibrous reinforcing material is used, a so-called impregnation method described in JP 2001-187831 A can be employed. In short, a fibrous reinforcing material formed into a sheet may be immersed in a coating tank in which the dielectric powder and the resin are adjusted in a slurry.

  Non-fibrous reinforcing materials include silicates such as wollastonite, sericite, kaolin, mica, clay, bentonite, asbestos, talc, alumina silicate, pyrophyllite, montmorillonite, molybdenum disulfide, alumina, silicon chloride , Zirconium oxide, iron oxide, calcium carbonate, magnesium carbonate, sulfate such as dolomite, sulfate such as calcium sulfate, barium sulfate, calcium polyphosphate, graphite, glass beads, glass microballoon, glass flake, boron nitride, silicon carbide and Examples thereof include needle-like, plate-like, or granular reinforcing materials such as silica, and these may be hollow. What is necessary is just to add to resin, when using a non-fibrous reinforcement.

These reinforcing materials may be used alone or in combination of two or more, and may be used after pretreatment with a silane-based or titanium-based coupling agent if necessary. A particularly preferred reinforcing material is glass fiber. The type of glass fiber is not particularly limited as long as it is generally used for resin reinforcement. For example, glass fibers such as long fiber type and short fiber type chopped strands, chopped strand mats, continuous long fiber mats, woven fabrics and knitted fabrics. , Milled fiber and the like can be used.
The content of the reinforcing material in the composite dielectric material is preferably in the range of 10 to 30 wt%. More preferably, it is 15-25 wt%.

  The composite dielectric material of the present invention can be used in various forms such as a film, a molded body of a bulk shape or a predetermined shape, and a lamination of a film shape. Accordingly, various substrates for high-frequency electronic devices and electronic components (resonators, filters, capacitors, inductors, antennas, etc.), filters as chip components (for example, C filters that are multilayer substrates) and resonators (for example, triplate resonators) ), Or a support such as a dielectric resonator, and further, a housing for various substrates or electronic components (for example, an antenna rod housing), a casing, an electronic component, its housing or casing, and the like.

Hereinafter, the present invention will be described based on specific examples.
The following raw material powders were weighed with a composition of (Sr _0.64 Ca _0.36 ) TiO ₃ , A / B (molar ratio of A site atoms to B site atoms) = 0.994, and wet mixed by a ball mill. As the B site raw material, nine types of TiO ₂ powders having different BET values and D50 (particle diameter of the cumulative number of 50%) shown in Table 1 were prepared.
A-site raw material SrCO ₃ powder (BET value = 6.0 m ^{2 /} g, D50 = 0.50 μm)
CaCO ₃ powder (BET value = 18.8 m ^{2 /} g, D50 = 0.30 μm)
B site raw material TiO ₂ powder (BET value = 2.9 to 51.3 m ^{2 /} g, D50 = 1.75 to 0.27 μm)

Using a 6-inch pot as a ball mill and ZrO ₂ balls (φ10 mm: 1 kg, φ3 mm: 2 kg) as media, the treatment was performed at 120 rpm for 16 hours. The ball mill was charged with 800 g of mixed powder, and the slurry concentration was 33%. Further, prior to mixing, 0.2 wt% of a dispersant (manufactured by Toagosei Co., Ltd .: A-30SL) was added.
After the wet mixing by the ball mill was completed, drying was carried out using a dryer at a temperature of 120 ° C. for 24 hours.
The dried mixed powder was passed through a 355 μm mesh, and then fired (first firing) by being held at 1150 ° C. for 2 hours in a MgO bee.

The fired product (first fired product) obtained using a ball mill was pulverized. Using a 4-inch pot as a ball mill and ZrO ₂ balls (φ10 mm: 200 g, φ3 mm: 430 g) as media, treatment was performed at 120 rpm for 16 hours. In addition, 150 g of the fired product was put in the pot, and the slurry concentration was 33%.
After pulverization by the ball mill was completed, drying was carried out using a dryer at a temperature of 120 ° C. for 24 hours. This powder is hereinafter referred to as a first powder.
While measuring the particle size distribution of 1st powder, D50 was calculated | required. The particle size distribution was measured using a Microtrac ultrafine particle size distribution meter (manufactured by Nikkiso Co., Ltd .: 9340-UPA150).

Table 1 shows the measurement results of D50 of the first powder. FIG. 1 shows the relationship between the BET value of the B-site raw material powder (TiO ₂ powder) and D50 of the first powder. From Table 1 and FIG. 1, it can be seen that by setting the BET value to 20 m ² / g or more, the D50 of the first powder can be 1.0 μm or less, and further 0.8 μm or less. This indicates that a finer dielectric powder can be obtained with the same pulverization time. According to the present invention, it is possible to obtain a fine dielectric powder with less dielectric distortion and high dielectric properties. Suggests.

Next, after adding the powder of the following subcomponents with respect to 100 mols of nine kinds of first powders, wet mixing was performed by a ball mill. Using a 4-inch pot as a ball mill and ZrO ₂ balls (φ10 mm: 200 g, φ3 mm: 430 g) as media, treatment was performed at 120 rpm for 16 hours. In addition, 100 g of the first powder was introduced into the pot, and the slurry concentration was 33%. Further, prior to mixing, 0.2 wt% of a dispersant (manufactured by Toagosei Co., Ltd .: A-30SL) was added.
MnO (D50 = 0.55 μm): 0.365 mol V ₂ O ₅ (D50 = 0.52 μm): 0.1 mol Y ₂ O ₃ (D50 = 0.33 μm): 0.035 mol CaSiO ₃ (D50 = 1.178 μm): 1.616 mol

After the wet mixing by the ball mill was completed, it was dried using a drier at a temperature of 120 ° C. for 24 hours.
The dried mixed powder was passed through a 355 μm mesh, and then fired (second firing) by being held at 1150 ° C. for 2 hours in a MgO bee.

The fired product (second fired product) obtained using a ball mill was pulverized. Using a 4-inch pot as a ball mill and ZrO ₂ balls (φ10 mm: 200 g, φ3 mm: 430 g) as media, treatment was performed at 120 rpm for 16 hours. The ball mill was charged with 100 g of the fired product and the slurry concentration was 33%.
After the wet mixing by the ball mill was completed, it was dried using a drier at a temperature of 120 ° C. for 24 hours. This powder is hereinafter referred to as a second powder.

The second powder obtained above and the organic polymer resin were kneaded using a pot mill. As the organic polymer resin, a benzyl resin (εr = 2.5, tan δ = 1 × 10 ⁻⁴ ) was used. For kneading, 60 g of φ10 mm ZrO ₂ balls were put into a 100 ml pot and treated at 120 rpm for 3 hours. Also, 15 g of the second powder and benzyl resin were added into the pot so that the content of the second powder was 40 vol%.
After completion of the kneading, the kneaded product was formed into a sheet and then dried by holding at 110 ° C. for 2 hours in a dryer. Then, after press molding at a temperature of 150 ° C., the temperature was raised to 180 ° C. to completely cure the resin. After the resin was cured, a sample (composite dielectric material) having a size of 1 mm square and a length of 80 mm or more was cut out from the sheet.

The dielectric constant (εr) and Q value of the above composite dielectric material were measured by the perturbation method (n = 3). The results are shown in Table 1. The measurement was performed using an HP 8510, an RF vector network analyzer manufactured by Hewlett-Packard Company.
FIG. 2 shows the relationship between the BET value of the B site raw material powder, the relative dielectric constant (εr) and the Q value of the composite dielectric material. As shown in FIG. 2, as the BET value of the B-site raw material powder increases, the relative dielectric constant (εr) and Q value of the composite dielectric material increase. However, the relative dielectric constant (εr) and the Q value of the composite dielectric material tend to decrease with the BET value peaking at 30 m ² / g. From this result, in the present invention, when obtaining a composite dielectric material, the B-site raw material powder has a BET value of 20 to 40 m ² / g, preferably 25 to 35 m ² / g.

And BET value of B site material powder (TiO ₂ powder), is a graph showing the relationship between D50 of the first powder. And BET value of B site material powder (TiO ₂ powder), is a graph showing the relationship between the relative dielectric constant (.epsilon.r) and Q value of the composite dielectric material.

Claims (7)

A method for producing a dielectric powder containing a perovskite oxide having an ABO ₃ type atomic arrangement,
A first firing step of firing a mixture containing the A site raw material powder constituting the A site and the B site raw material powder having a BET value of 20 m ² / g or more constituting the B site to obtain a first fired product;
And a first pulverization step of pulverizing the first fired product to obtain a first powder. A second firing step of obtaining a second fired product by firing after applying a predetermined treatment to the first powder obtained in the first grinding step;
The method for producing a dielectric powder according to claim 1, further comprising: a second pulverization step of pulverizing the second fired product to obtain a second powder. In the perovskite oxide having the ABO ₃ type atomic arrangement, the A site contains one or more atoms selected from Ba, Ca and Sr, and the B site is selected from Ti, Zr and Nb. The method for producing a dielectric powder according to claim 1, wherein the dielectric powder contains one or more atoms.   4. The dielectric powder according to claim 1, wherein the first powder or the second powder has a D50 (particle diameter of a cumulative number of 50%) of 1 μm or less. Production method. A method for producing a composite dielectric material comprising a dielectric powder comprising a perovskite oxide having an ABO ₃ type atomic arrangement and a resin,
A step of obtaining a dielectric powder by pulverizing a fired product made from an A site raw material powder constituting the A site and a B site raw material powder having a BET value of 20 to 40 m ² / g constituting the B site;
And a step of compositing the dielectric powder and a resin. In the perovskite oxide having the ABO ₃ type atomic arrangement, the A site is composed of one or more atoms selected from Ba, Ca and Sr, and the B site is selected from Ti, Zr and Nb. 6. The method for producing a composite dielectric material according to claim 5, wherein the composite dielectric material is composed of one or more kinds of atoms.   7. The method for producing a composite dielectric material according to claim 5, wherein D50 of the dielectric powder (particle diameter of accumulated particles of 50%) is 1 μm or less.

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