JP2013203643A - Dielectric ceramic and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric ceramic having a high Q.f value and high flexural strength, and to provide a dielectric ceramic especially having a high Q.f value and high flexural strength, whereas, though εr can be lowered suitably by adding glass to a BaO-NdO-TiOcompound, the Q.f value is sometimes lowered, and when the Q.f value is lowered, a power loss of an electronic component becomes large, and further the flexural strength may cause a trouble in practical use.SOLUTION: A dielectric ceramic includes at least Ba, Nd, Ti and Zn as metal elements, and includes a tungsten bronze type crystal phase as a main crystal phase. The dielectric ceramic includes a tungsten bronze type crystal phase containing BaNdTiOor BaNdTiO, and a ZnO-TiO-based crystal phase.

Description

  The present invention relates to a dielectric ceramic suitable for an electronic component used in a high frequency region such as a microwave and a millimeter wave, and an electronic component using the dielectric ceramic.

  2. Description of the Related Art In recent years, mobile communication devices such as mobile phones, for which demand is increasing, use a high frequency band called a quasi-microwave band of about several hundred MHz to several GHz. Therefore, electronic parts having excellent high frequency characteristics are required as electronic parts such as filters, resonators, and capacitors used in mobile communication devices. In addition, with the recent miniaturization of mobile communication devices, these electronic components are also required to be miniaturized.

  In order to contribute to the miniaturization of such electronic components, electronic components used in mobile communication devices have internal conductors such as electrodes and wiring (hereinafter referred to as "internal electrodes and wiring conductors" A surface mount device (SMD: Surface Mount Device) having a “conductor”) has become the mainstream.

Further, in order to realize a reduction in the price of electronic components, it is desired that a low-resistance and inexpensive conductor such as Ag can be used as the internal conductor. With respect to dielectric ceramic compositions having a low temperature sintering property that can use Ag as an internal conductor, those having various compositions have been proposed. For example, a material mainly composed of a BaO-rare earth oxide-TiO ₂ compound has a wide relative dielectric constant (εr), a large Q · f value, a small resonance frequency temperature characteristic (τf), and the like. Research has been done.

  Furthermore, research is being conducted on technology to fabricate multilayer electronic components with improved characteristics by simultaneously firing different materials of the above-mentioned dielectric ceramics with high εr and dielectric ceramics with smaller εr. Has been.

  However, when producing such a multilayer electronic component, if the material composition of the dielectric ceramic composition having a high εr and that of a dielectric ceramic composition having a low εr are significantly different from each other, the shrinkage during firing of both Since the behavior and the coefficient of linear expansion are difficult to match, when both dielectric ceramic compositions are bonded and fired, defects such as cracks and peeling will occur on the bonded surface.

  From this point of view, when forming a multilayer electronic component, the dielectric ceramic composition having a high εr and the dielectric ceramic composition having a low εr are basically composed of the same material or a similar material. It is desirable to have almost the same physical properties.

For example, Patent Document 1 discloses a dielectric ceramic composition in which εr is reduced by adding glass to a high εr BaO—Nd ₂ O ₃ —TiO ₂ compound.

JP 2005-001940 A

However, when glass is added to the BaO—Nd ₂ O ₃ —TiO ₂ compound described above, εr can be suitably reduced, but the Q · f value tends to decrease. If the Q · f value decreases, the power loss of the electronic component may increase.
Furthermore, the bending strength may be a problem in practical use.

  The present invention has been made in view of the above circumstances, and has as its main object to provide a dielectric ceramic having a large Q · f value and high bending strength.

As a result of intensive studies in view of the above circumstances, the present inventors have found that a dielectric comprising a tungsten bronze type crystal phase and a ZnO—TiO ₂ based crystal phase has a large Q · f value and a high bending strength. The porcelain was found and the present invention was completed.

That is, the dielectric ceramic according to the present invention is a dielectric ceramic containing at least Ba, Nd, Ti, and Zn as metal elements and having a tungsten bronze type crystal phase as a main crystal phase, and is a BaNd ₂ Ti ₄ O ₁₂ or The tungsten bronze-type crystal phase containing any of BaNd ₂ Ti ₅ O ₁₄ and a ZnO—TiO ₂ -based crystal phase are included.

The tungsten bronze type crystal phase is at least one of a BaNd ₂ Ti ₄ O ₁₂ crystal phase and a BaNd ₂ Ti ₅ O ₁₄ crystal phase. The BaNd ₂ Ti ₄ O ₁₂ crystal phase and the BaNd ₂ Ti ₅ O ₁₄ crystal phase described above are not limited to BaNd ₂ Ti ₄ O ₁₂ and BaNd ₂ Ti ₅ O ₁₄ , respectively. For example, Nd May be substituted with other rare earth elements.

Furthermore, the above ZnO—TiO ₂ based crystal phase is not limited to those composed of ZnO and TiO ₂ such as ZnTiO ₃ and Zn ₂ TiO _4, but is composed of (Zn, Mg) TiO ₃ , (Zn, Cu ) Zn sites may be substituted with other divalent ions such as TiO ₃ .

With the above crystal phase configuration, a dielectric ceramic having a large Q · f value and high bending strength can be obtained.

  In this specification, the “dielectric porcelain composition” is a raw material composition of a dielectric porcelain, and the “dielectric porcelain” that is a sintered body is obtained by sintering the dielectric porcelain composition. can get. “Sintering” is a phenomenon in which when a dielectric ceramic composition is heated, the dielectric ceramic composition becomes a dense object called a sintered body. In general, the density, mechanical strength, etc. of the sintered body are increased as compared with the dielectric ceramic composition before heating. The “sintering temperature” is the temperature of the dielectric ceramic composition when the dielectric ceramic composition is sintered. Further, “firing” means a heat treatment for the purpose of sintering, and “firing temperature” indicates the temperature of the atmosphere to which the dielectric ceramic composition is exposed during the heat treatment.

In the present invention, the volume ratio x of all crystal grains of the ZnO—TiO ₂ based crystal phase is preferably 0.1 (volume%) ≦ x <10 (volume%).

A ZnO—TiO ₂ based crystal phase is known to have a low εr and a negative τf, while having a large Q · f value exceeding 20000 GHz.
By setting the volume ratio of the ZnO—TiO ₂ based crystal phase to the main crystal particles within the above preferred range, the Q · f value of the dielectric ceramic can be reduced without impairing the sinterability of the dielectric ceramic composition. It is possible to suitably increase the dielectric ceramic, and it is possible to suitably decrease εr of the dielectric ceramic, and to reduce the absolute value of τf.

  According to another aspect of the present invention, there is provided an electronic component formed of a laminate of the dielectric ceramic and a layer containing a metal, thereby obtaining a laminated structure electronic component having the metal layer as an internal conductor.

  According to the present invention, it is possible to provide a dielectric ceramic having a large Q · f value and high bending strength.

FIG. 1 is a schematic cross-sectional view showing a configuration of a bandpass filter obtained using the dielectric ceramic according to the present embodiment. FIG. 2 is a diagram showing the X-ray diffraction measurement results of the dielectric ceramic of Example 5. FIG. 3 is a diagram showing the results of mapping Ba elements by STEM-EDS for the dielectric ceramic of Example 5. FIG. 4 is a diagram showing the result of mapping Nd elements by STEM-EDS for the dielectric ceramic of Example 5. FIG. 5 is a diagram showing the result of mapping of Ti element by STEM-EDS for the dielectric ceramic of Example 5. FIG. 6 is a diagram showing the result of mapping of the Zn element by STEM-EDS for the dielectric ceramic of Example 5. FIG. 7 is a diagram showing a result of mapping of Mg element by STEM-EDS for the dielectric ceramic of Example 5. FIG. 8 is a diagram showing the results of mapping of the Si element by STEM-EDS for the dielectric ceramic of Example 5.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented with appropriate modifications within the scope of the gist thereof.

The dielectric ceramic of the present embodiment is a dielectric ceramic containing at least Ba, Nd, Ti, and Zn as metal elements and having a tungsten bronze type crystal phase as a main crystal phase, and is BaNd ₂ Ti ₄ O ₁₂ or BaNd. _The tungsten bronze type crystal phase containing any one of ₂ Ti ₅ O ₁₄ and a ZnO—TiO ₂ based crystal phase are included.

A dielectric ceramic made of a tungsten bronze type crystal phase containing either BaNd ₂ Ti ₄ O ₁₂ or BaNd ₂ Ti ₅ O ₁₄ has a high εr, and its value is about 100. On the other hand, the ZnO—TiO ₂ based crystal phase has a low εr and its value is about 20. In the dielectric ceramic according to the present embodiment, the tungsten bronze type crystal phase having a high εr can contain a ZnO—TiO ₂ based crystal phase having a low εr, whereby the εr of the dielectric ceramic can be suitably reduced.

Whether or not the dielectric ceramic contains a tungsten bronze crystal phase and a ZnO—TiO ₂ crystal phase can be confirmed by an X-ray diffractometer (XRD).

A dielectric layer formed from the dielectric ceramic according to the present embodiment is joined to a dielectric layer formed from a conventionally known BaO-rare earth oxide-TiO ₂ dielectric ceramic (high dielectric constant material) to form a multilayer type. In the case of forming an electronic component, the multilayer electronic component can have higher characteristics as εr of the dielectric ceramic of the present embodiment is lower than εr of the high dielectric constant material.

Here, the tungsten bronze type crystal phase often has a positive τf. On the other hand, the ZnO—TiO ₂ crystal phase has a negative τf. In the present embodiment, positive τf and negative τf are obtained by including a dielectric bronze in a tungsten bronze type crystal phase having a positive τf and a ZnO—TiO ₂ based crystal phase having a negative τf. This cancels out the absolute value of τf of the dielectric ceramic. Note that τf and the Q · f value described later are values indicated by the dielectric ceramic composition after sintering, that is, the dielectric ceramic.

  Further, τf (unit: ppm / K) of the dielectric ceramic is calculated by the relationship represented by the following formula (1).

τf = [(f _T −f _ref ) / f _ref ] / (T−T _ref ) × 10 ⁶ (ppm / K) (1)

In equation (1), f _T represents the resonance frequency (GHz) at the temperature T, and f _ref represents the resonance frequency (GHz) at the reference temperature T _ref . The magnitude of the absolute value of τf means the magnitude of change in the resonant frequency of the dielectric ceramic with respect to temperature change. In electronic parts such as capacitors and dielectric filters, it is necessary to reduce the change in resonance frequency due to temperature, and therefore it is required to reduce the absolute value of τf of the dielectric ceramic.

  Τf of the dielectric ceramic according to the present embodiment is preferably −40 ppm / K to +40 ppm / K, more preferably −20 ppm / K to +20 ppm / K, and −10 ppm / K to +10 ppm / K. More preferably. By setting τf to a value within the above preferred range, when using a dielectric ceramic as a dielectric resonator, the temperature change of the resonance frequency of the dielectric resonator can be reduced, and the dielectric resonator can be High performance can be achieved.

Further, the Q · f value of a dielectric ceramic made of a tungsten bronze type crystal phase is approximately 5000 GHz. On the other hand, since the ZnO—TiO ₂ crystal phase has a small dielectric loss, it has a large Q · f value, which is known to exceed 20000 GHz. The dielectric ceramic of this embodiment can suitably increase the Q · f value of the dielectric ceramic by including ZnO—TiO ₂ crystal grains in addition to the tungsten bronze type crystal phase.

  The Q · f value (unit: GHz) of the dielectric ceramic represents the magnitude of the dielectric loss, which is the difference between the actual current and voltage phase difference and the ideal current and voltage phase difference of 90 degrees. It is the product of the reciprocal Q (Q = 1 / tan δ) of the tangent tan δ of a certain loss angle δ and the resonance frequency f.

Furthermore, in the dielectric ceramic according to the present embodiment, the volume ratio x of all crystal grains of the ZnO—TiO ₂ crystal phase is
0.1 (volume%) ≦ x <10 (volume%)
It is characterized by

In the dielectric ceramic according to the present invention, the ZnO—TiO ₂ based crystal phase may be added in advance, or may be generated in a heat treatment step.

In order to generate a ZnO—TiO ₂ crystal phase in the heat treatment step, it is necessary to previously contain zinc oxide (ZnO) in the tungsten bronze type crystal powder.

  The heat treatment step refers to a step of calcining the dielectric ceramic composition, a step of firing, and a step of annealing the dielectric ceramic after firing.

In order to make the ZnO—TiO ₂ -based crystal phase more stable, it is preferable to further anneal after firing.

  Furthermore, in order to allow the dielectric ceramic composition to be fired simultaneously with the Ag-based conductor at a temperature lower than the melting point of the conductor material made of Ag-based metal, the sintering is promoted at such a low temperature. It may further contain components.

  Examples of components that promote sintering at such low temperatures include, but are not limited to, zinc oxide, boron oxide, bismuth oxide, copper oxide, glass, and alkali metal oxides. is not.

  Furthermore, transition metal oxides and alkaline earth metal oxides may be included as components for controlling dielectric properties and sinterability.

When the volume ratio of the ZnO—TiO ₂ -based crystal phase to all crystal grains is less than 0.1%, the Q · f value is not improved. On the other hand, when it is 10 or more, the effect of increasing the Q · f value tends to be lost, which is not preferable. Therefore, by setting the volume ratio of the ZnO—TiO ₂ based crystal phase within the above-mentioned preferable range, these disadvantageous trends can be suppressed.

  Since the dielectric ceramic according to the present embodiment is made of crystal particles instead of a glass ceramic structure, the bending strength can be further increased.

Here, the dielectric layer formed from the dielectric ceramic according to the present embodiment is joined to the dielectric layer formed from a conventionally known BaO-rare earth oxide-TiO ₂ dielectric ceramic (high dielectric constant material). When the multilayer electronic component is formed, the multilayer electronic component can be improved in characteristics as the εr of the dielectric ceramic according to the present embodiment is lower than the εr of the high dielectric constant material. Therefore, the εr of the dielectric ceramic according to the present embodiment can be improved. Should be even smaller.

  As a technique for that, a dielectric ceramic having a lower εr may be further added to the dielectric ceramic of the present embodiment.

Examples of the dielectric ceramic having a low εr include, but are not limited to, Al ₂ O ₃ , MgO, MgAl ₂ O ₄ , MgSiO ₃ , and Mg ₂ SiO ₄ .

In this embodiment, since the BaO—Nd ₂ O ₃ —TiO ₂ based compound is included as the main component of the dielectric ceramic composition, the conventional BaO—rare earth oxide—TiO ₂ based dielectric ceramic composition (high It is similar to the material of εr material. Therefore, the shrinkage behavior and the linear expansion coefficient during firing of the dielectric ceramic composition of the present embodiment are equivalent to those of the high εr material. Therefore, even when the dielectric ceramic composition of the present embodiment and the high εr material are joined and baked to produce a multilayer electronic component, defects are hardly generated on the joint surface, and the appearance of the electronic component is good. It is possible to obtain a multilayer electronic component having high characteristics.

<Manufacturing method>
Next, an example of a method for manufacturing the dielectric ceramic according to the present embodiment will be described.

As each raw material of the dielectric ceramic, for example, BaO—Nd ₂ O ₃ —TiO ₂ based compound, ZnO—TiO ₂ based compound, zinc oxide, boron oxide, or firing (heat treatment such as calcination described later) is performed. Compounds that can be used as these oxides can be used.

  Examples of the compound that can be converted into the oxide by firing include carbonates, nitrates, oxalates, hydroxides, sulfides, and organometallic compounds.

(Main component)
First, barium carbonate, neodymium hydroxide, and titanium oxide, which are raw materials for the main component, are weighed in predetermined amounts and mixed.

  Mixing of barium carbonate, neodymium hydroxide and titanium oxide can be performed by a mixing method such as dry mixing or wet mixing. For example, it can be performed by a ball mill using pure water, ethanol or the like. The mixing time may be about 4 to 24 hours, for example.

The mixture of barium carbonate, neodymium hydroxide and titanium oxide is preferably dried at about 100 to 200 ° C., more preferably 120 to 140 ° C. for about 12 to 36 hours, followed by calcination. A BaO—Nd ₂ O ₃ —TiO ₂ compound is synthesized by this calcination. The calcination temperature is preferably 1100 to 1500 ° C, and more preferably 1100 to 1350 ° C. Moreover, it is preferable to perform calcination for about 1 to 24 hours.

The synthesized BaO—Nd ₂ O ₃ —TiO ₂ compound is pulverized into a powder and then dried. Thereby, a powder of a tungsten bronze type crystal phase is obtained. The pulverization can be performed by a pulverization method such as dry pulverization or wet pulverization. The wet pulverization can be performed by, for example, a ball mill using pure water, ethanol or the like. The pulverization time may be about 4 to 24 hours. The powder may be dried at a drying temperature of preferably 100 to 200 ° C., more preferably 120 to 140 ° C. for about 12 to 36 hours.

(Subcomponent)
Next, a predetermined amount of the main component powder of the obtained dielectric ceramic composition and zinc oxide and boron oxide, which are subcomponent raw materials of the dielectric ceramic composition, are weighed, and then mixed. The raw material mixed powder is obtained.

  Mixing can be performed by a mixing method such as dry mixing or wet mixing. For example, it can be performed by a ball mill using pure water, ethanol or the like. The mixing time may be about 4 to 24 hours.

  The raw material mixed powder is preferably dried at a drying temperature of 100 to 200 ° C., more preferably 120 to 140 ° C. for about 12 to 36 hours.

The raw material mixed powder is calcined for about 1 to 10 hours at a temperature equal to or lower than a firing temperature (850 to 950 ° C.) described below, for example, 700 to 850 ° C. By calcining at such a temperature, a ZnO—TiO ₂ -based crystal phase having a large Q value can be generated in advance in the raw material mixed powder. As a result, the Q value of the dielectric ceramic can be further increased.

  The raw material mixed powder after calcination is pulverized and then dried to obtain a dielectric ceramic composition. The pulverization can be performed by a pulverization method such as dry pulverization or wet pulverization. The wet pulverization can be performed by, for example, a ball mill using pure water, ethanol or the like. The pulverization time may be about 4 to 24 hours. Drying of the pulverized powder is preferably performed at a treatment temperature of 100 to 200 ° C., more preferably 120 to 140 ° C. for about 12 to 36 hours.

  The powder obtained as described above is mixed with an acrylic, ethyl cellulose, or nylon organic binder, and then molded into a desired shape, and the molded product is fired and sintered. The molding may be wet molding such as a sheet method or a printing method, or dry molding such as press molding, and a molding method can be appropriately selected according to a desired shape. In addition, firing is preferably performed, for example, in an oxygen atmosphere such as in the air, and the firing temperature is preferably equal to or lower than the melting point of a conductor such as Ag or an alloy containing Ag as a main component that can be used as an internal electrode. Specifically, the firing temperature is more preferably 850 to 950 ° C, and further preferably 880 to 920 ° C.

The holding time at the firing temperature affects the formation of the ZnO—TiO ₂ crystal phase.
Specifically, the holding time is preferably 0.5 to 10 hours, more preferably 1 to 7 hours, and even more preferably 2 to 5 hours.

Furthermore, the dielectric ceramic obtained by firing is annealed at a temperature equal to or lower than the firing temperature described above, for example, 700 to 850 ° C. for about 1 to 10 hours. By annealing at such a temperature, the ZnO—TiO ₂ crystal phase can be made more stable. As a result, the Q value of the dielectric ceramic can be further increased.

  The dielectric ceramic composition of the present embodiment can be suitably used as a raw material for a multilayer electronic component that is a kind of electronic component, for example. A multilayer electronic component is manufactured from a multilayer ceramic substrate composed of a plurality of ceramic layers in which dielectric devices such as capacitors and inductors are integrally formed (embedded integrally). This multilayer ceramic substrate can be manufactured by forming a through hole in a green sheet made of a dielectric ceramic composition having different dielectric properties, and then laminating a plurality of green sheets and simultaneously firing them.

  In the production of multilayer electronic components, the dielectric ceramic composition of the present embodiment is mixed with an organic binder such as acrylic or ethyl cellulose, and the resulting mixture is molded into a sheet to obtain a green sheet. obtain. As a green sheet forming method, a wet forming method such as a sheet method is used.

  Next, a plurality of the obtained green sheets and other green sheets having different dielectric characteristics are alternately laminated in a state in which an Ag-based metal serving as an internal electrode is disposed between the green sheets. Is cut to a desired dimension to form a green chip. After the binder removal treatment is performed on the obtained green chip, the green chip is fired to obtain a sintered body. Firing is preferably performed in an oxygen atmosphere such as in air. Moreover, it is preferable that it is below melting | fusing point of Ag type metal used as a conductor material, specifically, it is preferable that it is 850-950 degreeC, and it is more preferable that it is 880-920 degreeC. By forming an external electrode or the like on the obtained sintered body, a multilayer electronic component having an internal electrode made of an Ag-based metal can be manufactured.

Electronic components obtained using the dielectric ceramic according to the present embodiment include, for example, a band-pass filter for high-frequency communication in a mobile phone, a smartphone, or the like. FIG. 1 is a schematic cross-sectional view showing a configuration example of a bandpass filter obtained using the dielectric ceramic according to the present embodiment.
As shown in FIG. 1, the bandpass filter 1 includes a plurality of dielectric layers 2, a coil pattern portion L 1, capacitor pattern portions C 1 to C 3, and vias (via conductors) 3. The dielectric layer 2 is made of a dielectric ceramic composition used to form the dielectric ceramic of the present embodiment. The coil pattern portion L1 and the capacitor pattern portions C1 to C3 are formed of an Ag conductor. The via 3 is a via hole portion filled with an Ag conductor for conducting the coil pattern portion L1 and the capacitor pattern portion C1, and an LC resonance circuit is formed by electrically connecting the coil pattern portion and the capacitor pattern portion. Has been.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.

[Examples 1 to 6]
The dielectric ceramics of Examples 1 to 6 were manufactured so that the amount of zinc oxide (ZnO) added to the dielectric ceramic composition was the value shown in Table 1. Then, these dielectric properties (Q · f value, τf) and bending strength were measured using the obtained measurement samples made of dielectric ceramics. These results are summarized in Table 1. The dielectric ceramic production method, measurement sample production method, and evaluation method are all the same as in Example 5 except that the addition amount of zinc oxide shown in Table 1 is changed. It was.

Example 5
When the composition formula of the BaO—Nd ₂ O ₃ —TiO ₂ compound is expressed as aBaO—bNd ₂ O ₃ —cTiO ₂ , a = 17.0 (mol%), b = 16.0 (mol%), a main component containing tungsten bronze-type crystals of c = 67.0 (mol%) and Mg ₂ SiO ₄ crystals, the mass ratios of which are 70% by mass and 30% by mass, respectively, and the main component of 100% by mass On the other hand, a dielectric ceramic composition containing 9.0% by mass of ZnO and 4.5% by mass of B ₂ O ₃ as subcomponents was prepared by the following procedure.

First, the molar ratios a, b, and c in aBaO-bNd ₂ O ₃ -cTiO ₂ obtained after calcining BaCO ₃ , Nd (OH) _3, and TiO ₂ that are raw materials of the main components are the above values. Each was weighed so that

Pure water was added to the weighed raw materials, wet-mixed with a ball mill, and then dried at 120 ° C. to obtain a mixed powder. This powder was calcined in air at 1200 ° C. for 4 hours, and the composition formula was aBaO—bNd ₂ O ₃ —cTiO ₂ (a = 17.0 (mol%), b = 16.0 (mol%). ), C = 67.0 (mol%)), a BaO—Nd ₂ O ₃ —TiO ₂ compound represented by the following formula was obtained. Pure water was added to the BaO—Nd ₂ O ₃ —TiO ₂ compound, pulverized by a ball mill, and then dried at 120 ° C. to produce a BaO—Nd ₂ O ₃ —TiO ₂ compound powder.

Next, MgO and SiO ₂ were weighed so that the number of moles of magnesium atoms was twice the number of moles of silicon atoms. Pure water was added to the weighed raw materials, wet-mixed with a ball mill, and then dried at 120 ° C. to obtain a mixed powder. This powder was calcined in the air at 1200 ° C. for 3 hours to obtain Mg ₂ SiO ₄ crystals. Pure water was added to the Mg ₂ SiO ₄ crystal, pulverized with a ball mill, and then dried at 120 ° C. to produce a powder of Mg ₂ SiO ₄ crystal.

And next, with respect to the mixture obtained by mixing the obtained BaO—Nd ₂ O ₃ TiO ₂ -based compound powder and Mg ₂ SiO ₄ crystal powder in a mass ratio of 70:30, the dielectric ceramic composition After blending ZnO and B ₂ O ₃ which are raw materials of subcomponents of the product, pure water was further added to prepare a slurry. This slurry was wet mixed by a ball mill and then dried at 120 ° C. to obtain a raw material mixed powder. The obtained raw material mixed powder was calcined in air at 800 ° C. for 4 hours to obtain a calcined powder. Next, ethanol was added to the obtained calcined powder, wet pulverized with a ball mill, and then dried at 100 ° C. to obtain a dielectric ceramic composition powder of Example 5.

Each amount of the _BaO-Nd 2 O 3 ZnO for a mixture of powder of powder and _Mg 2 SiO ₄ crystal -TiO ₂ based compound, and _B 2 _{O 3} is, ZnO is 9.0 mass%, _{B 2} O ₃ is 4.5 wt%, was adjusted to be contained respectively.

  The powder of the dielectric ceramic composition of Example 5 which was granulated by adding an aqueous nylon resin solution as a binder was press-molded, fired in air at 920 ° C. for 4 hours, and further heated at 800 ° C. for 2 hours. The sample was subjected to time annealing to obtain a dielectric ceramic as a sample for measurement.

(Dielectric property measurement)
The Q · f value (unit: GHz) and τf (unit: ppm / K) indicating the dielectric properties of the measurement sample of Example 5 were determined using the Japanese Industrial Standard “Test Method for Dielectric Properties of Microwave Fine Ceramics” (JIS). R 1627 (1996). These measurement results are also shown in Table 1. In addition, (tau) f was calculated from Formula (1) by measuring the resonant frequency in the temperature range of 20-85 degreeC, and making the reference temperature into 20 degreeC.

(Bending strength measurement)
The bending strength σ (unit: MPa) of the dielectric ceramic of Example 5 was measured in accordance with the Japanese Industrial Standard “Method for Testing the Bending Strength of Fine Ceramics at Room Temperature” (JIS R 1601 2008). These measurement results are shown in Table 1.

(Confirmation of crystal phase in dielectric ceramic)
For the dielectric ceramic of Example 5, the crystal phase was identified by X-ray diffraction measurement. FIG. 2 shows a chart in the X-ray diffraction measurement. As shown in FIG. 2, the dielectric ceramic of Example 5 has a main crystal phase, a tungsten bronze crystal phase, BaNd ₂ Ti ₄ O ₁₂ crystal phase, Mg ₂ SiO ₄ crystal phase, and a ZnO—TiO ₂ crystal. It can be seen that a phase exists.

(Calculation of volume ratio of ZnO-TiO ₂ based crystal phase in dielectric ceramic)
About the dielectric ceramic of Example 5, each element is mapped by STEM-EDS (Scanning Transmission Electron Microscopy-Energy Dispersive Spectroscopy), and the place where Zn element and Ti element coexist is a ZnO-TiO ₂ phase crystal. The area ratio was calculated by image processing analysis. Next, assuming that all of the crystal particles are spherical particles having the average particle diameter, the volume ratio is converted to a volume ratio, and the volume ratio x (volume%) of the ZnO—TiO ₂ based crystal phase in all the crystal particles is calculated. did. 3 to 8 show the mapping results of each element by STEM-EDS. 3 shows the mapping result of Ba element, FIG. 4 shows the mapping result of Nd element, FIG. 5 shows the mapping result of Ti element, FIG. 6 shows the mapping result of Zn element, and FIG. 7 shows the mapping result of Mg element. FIG. 8 shows the mapping result of the Si element. Among these, the amount of ZnO—TiO ₂ crystal phase was estimated based on the images of FIGS. 5 and 6. The calculation results are also shown in Table 1.

In Examples 1 to 6, the Q · f value was 5000 GHz or more, τf was in the range of −10 ppm / K to +9 ppm / K, and σ was 270 MPa or more. That is, Examples 1 to 6 had good dielectric properties and high bending strength.
On the other hand, production of the measurement samples of Comparative Example 1 and Comparative Example 2 was also attempted in the same manner as in Example 5 except that the amount of zinc oxide added was changed to the amount shown in Table 1. In Comparative Example 1, a ZnO—TiO ₂ based crystal phase was not formed, and since the sinterability was lowered, the dielectric properties could not be measured, and the bending strength was small. In Comparative Example 2, the Q · f value was less than 5000 GHz due to the presence of an unreacted ZnO phase in spite of the presence of a ZnO—TiO ₂ -based crystal phase having a high Q · f value.
As described above, according to this example, it was shown that the dielectric ceramic according to this embodiment has a large Q · f value, a small τf, and a high bending strength.

  The dielectric ceramic according to the present invention can be used in various fields as various electronic components.

1 Band pass filter 2 Dielectric layer 3 Via (via conductor)
L1 Coil pattern part C1-C3 Capacitor pattern part 1

Claims (3)

A dielectric ceramic containing at least Ba, Nd, Ti and Zn as metal elements and having a tungsten bronze type crystal phase as a main crystal phase, wherein either BaNd ₂ Ti ₄ O ₁₂ or BaNd ₂ Ti ₅ O ₁₄ is used. A dielectric ceramic comprising the tungsten bronze-type crystal phase and a ZnO—TiO ₂ crystal phase. _2. The dielectric ceramic according to claim 1, wherein a volume ratio x of all crystal grains of the ZnO—TiO ₂ based crystal phase is 0.1 (volume%) ≦ x <10 (volume%).   The multilayer electronic component according to claim 1 or 2, wherein the multilayered electronic component is formed of a laminate of the dielectric ceramic and a layer containing a metal, thereby using the metal layer as an internal conductor. Electronic components.