JP4946875B2 - Dielectric porcelain composition - Google Patents

Description

  The present invention relates to a dielectric ceramic composition.

  In electronic devices such as mobile phones, the frequency band used has shifted to a high frequency, and it is required to use a dielectric material having excellent dielectric characteristics in the high frequency band for a dielectric filter used in the electronic device. Such dielectric characteristics mainly include a Q × f value (Q: quality factor, f: resonance frequency) and a temperature change coefficient τf of the resonance frequency f. Here, the quality factor Q is the reciprocal of the dielectric loss tangent tan δ. The Q × f value represents the loss characteristic of the dielectric material, and the larger the Q × f value, the lower the loss. Also, τf represents the temperature stability of the resonance frequency f, and the smaller the absolute value of τf is, the smaller the dielectric material changes with respect to the temperature change. Therefore, when a dielectric material having a large Q × f value and a small absolute value of the temperature change coefficient τf of the resonance frequency is used, a dielectric filter having a small loss and excellent temperature stability can be realized.

  On the other hand, in recent years, electronic devices such as mobile phones are required to be downsized, and accordingly, dielectric filters are also required to be downsized. For that purpose, the wavelength of the electromagnetic wave transmitted through the dielectric is generally shortened to 1 / √εr times according to the relative dielectric constant εr, and therefore it is effective to use a dielectric material having a high relative dielectric constant εr. ing.

  However, there is a trade-off relationship between the Q × f value and the relative dielectric constant εr. When the Q × f value increases, the relative dielectric constant εr decreases, and conversely, when the Q × f value decreases, the relative dielectric constant. The rate εr increases. Therefore, development of a dielectric material having all of the above-described Q × f value, temperature change coefficient τf, and relative dielectric constant εr in a well-balanced manner has been underway.

For example, in the following Patent Document 1, the following composition formula:
_{a · CaO -b · LiO 1/2 -c} · BiO 3/2 -d · REO 3/2 -e · TiO 2 ··· (1)
[In the above formula (1), RE represents at least one rare earth element selected from the group consisting of La, Ce, Pr, Nd, Sm, Dy, Yb and Y. A to e represent the ratio (mol%) of each component, 10 ≦ a ≦ 25, 10 ≦ b ≦ 20, 8 ≦ c ≦ 15, 2 ≦ d ≦ 10, 50 ≦ e ≦ 60, 0.65. ≦ b / (c + d) <1.0 and a + b + c + d + e = 100 are satisfied. It is proposed to realize a dielectric ceramic having a large Q × f value and a relative dielectric constant εr and a small temperature change coefficient τf of the resonance frequency by firing a dielectric ceramic composition including the basic composition represented by Has been.
JP 2006-273703 A

  By the way, in a multilayer component that requires simultaneous firing with the internal conductor material, such as a multilayer dielectric filter, an internal conductor material having a melting point higher than the sintering temperature of the dielectric material is used. Typical examples of such internal conductor materials include Pt (melting point: 1774 ° C .: specific resistance: 10.6 μΩ · cm) and Pd (1555 ° C .: specific resistance: 10.4 μΩ · cm), but these are precious metals and expensive. It is a thing.

  On the other hand, the characteristics of laminated parts are also greatly affected by the specific resistance of the internal conductor material. If an internal conductor material with a high specific resistance is used, there is a problem that the loss of the product increases. Use an internal conductor material with the lowest specific resistance as much as possible. It is hoped that.

  A conductor material with a small specific resistance is Ag (specific resistance 1.6 μΩ · cm), and the price per unit weight is about 30 times less than Pd, but the melting point is as low as 960 ° C. Too much.

  From the above, as an internal conductor material, an Ag—Pd alloy (for example, an Ag (70) -Pd (30) alloy (melting point: about 1230 ° C.), Ag (80) -Pd ( 20) Alloys (melting point: about 1160 ° C.), Ag (90) -Pd (10) alloys (melting point: about 1070 ° C.), etc. are desirable from the viewpoint of cost and characteristics.

  However, when the above-described Ag—Pd alloy is used as the internal conductor material of the multilayer component, the dielectric ceramic composition can be fired simultaneously with the dielectric ceramic composition described in Patent Document 1 above. It was difficult to realize a dielectric ceramic having a large Q × f value and relative dielectric constant εr and a small temperature change coefficient τf of the resonance frequency f.

  Therefore, the present invention can realize a dielectric ceramic having a large relative dielectric constant εr and Q × f value and good temperature stability of the resonance frequency, and can be fired even when simultaneously fired with an internal conductor material made of an Ag—Pd alloy. An object of the present invention is to provide a dielectric ceramic composition having good cohesiveness.

  In order to solve the above problems, the inventors pay attention to the amount of Bi in the composition formula (1), as well as the quantitative relationship between Bi and Ca and RE, the quantitative relationship between Li and RE, and Bi. As a result of intensive studies focusing on the quantitative relationship between other elements except for the above, the inventors have found that the above-described problems can be solved by the following invention.

That is, the present invention is a dielectric ceramic composition containing an oxide dielectric represented by the following composition formula (1).
_{a · CaO-b · LiO 1/2} -c · BiO 3/2 -d · REO 3/2 -e · TiO 2 ... (1)
[However, in the above formula (1), RE represents at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Dy, Yb and Y. A to e represent the ratio (mol%) of each component;
4 ≦ a ≦ 26
10 ≦ b ≦ 23
0 <c <8
2.5 ≦ d ≦ 25
50 ≦ e ≦ 60
0.65 ≦ b / (c + d) <1.0
b / d ≧ 0.90
(A + b + d) / e <1.0
0 ≦ c / d ≦ a × 0.06
a + b + c + d + e = 100
Satisfy the relationship. ]

  According to the dielectric ceramic composition of the present invention, it is possible to realize a dielectric ceramic having a large relative dielectric constant εr and Q × f value and good temperature stability of the resonance frequency, and an internal conductor material made of an Ag—Pd alloy; Sinterability is good even when co-firing.

  In addition, the composition of each element in the composition formula (1) is expressed as an analysis value obtained by analyzing the oxide dielectric alone by inductively coupled plasma emission spectroscopy and fluorescent X-ray analysis.

  According to the present invention, a dielectric ceramic having a large relative permittivity εr and Q × f value and good temperature stability of the resonance frequency can be realized, and can be fired even when simultaneously fired with an internal conductor material made of an Ag—Pd alloy. A dielectric ceramic composition having good cohesion is provided.

  Hereinafter, embodiments of the present invention will be described in detail.

[Dielectric porcelain composition]
The present invention is a dielectric ceramic composition containing an oxide dielectric represented by the following composition formula (1).
_{a · CaO-b · LiO 1/2} -c · BiO 3/2 -d · REO 3/2 -e · TiO 2 ... (1)
[However, in the above formula (1), RE represents at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Dy, Yb and Y. A to e represent the ratio (mol%) of each component;
4 ≦ a ≦ 26
10 ≦ b ≦ 23
0 <c <8
2.5 ≦ d ≦ 25
50 ≦ e ≦ 60
0.65 ≦ b / (c + d) <1.0
b / d ≧ 0.82
(A + b + d) / e <1.0
0 ≦ c / d ≦ a × 0.06
a + b + c + d + e = 100
Satisfy the relationship. ]

  Ca in the oxide dielectric has an effect of improving the relative dielectric constant εr and an effect of increasing the temperature change coefficient τf of the resonance frequency to the plus side. In order to realize a high relative dielectric constant εr exceeding 95, it is necessary that 4 mol or more of Ca is contained in terms of CaO, and if it is less than 4 mol%, the relative dielectric constant εr is too low. . On the other hand, in order to realize a temperature change coefficient | τf | smaller than 250 ppm / K in absolute value, Ca needs to be 26 mol% or less in terms of CaO. If it exceeds 26 mol%, the relative dielectric constant εr can be increased, but the temperature change coefficient τf of the resonance frequency becomes larger on the plus side and the temperature stability is deteriorated. Therefore, the content a of Ca in terms of CaO is 4 mol% or more and 26 mol% or less.

  Furthermore, in order to achieve both a high relative dielectric constant εr and stable temperature characteristics, the Ca content a in terms of CaO is preferably 10 mol% or more and 21 mol% or less.

  In the oxide dielectric, a part of Ca of the component CaO may be substituted with an alkaline earth metal element (one or more selected from Sr, Ba, and Mg). By substituting a part of Ca with an element having an ionic radius larger than Ca, such as Sr or Ba, the relative dielectric constant εr can be increased. Further, when a part of Ca is replaced with an element having an ion radius smaller than Ca, such as Mg, the Q × f value can be increased.

Li in the oxide dielectric affects the relative permittivity εr and the temperature change coefficient τf of the resonance frequency. The content b of Li in terms of LiO _1/2 is 10 mol% or more and 23 mol% or less. If it is less than 10 mol%, the temperature change coefficient τf of the resonance frequency is too large on the plus side. On the other hand, if it exceeds 23 mol%, the relative dielectric constant εr becomes too low.

Bi in the oxide dielectric has the effect of increasing the relative dielectric constant εr, while lowering the Q × f value. On the other hand, if it increases too much, the relative dielectric constant εr decreases, and the Q × f value also decreases. Therefore, it is necessary to determine an appropriate amount range from the balance of εr and Q × f value. In the case where the oxide dielectric is used as a high-temperature fired material, it is usually considered appropriate that the Bi amount is 8 mol% or more and 15 mol% or less. This is because if it exceeds 15 mol%, the Q × f value deteriorates, and if it is less than 8 mol%, there is a concern that the relative dielectric constant εr decreases and the temperature instability increases. However, when an Ag—Pd alloy is used as the internal conductor material, it has been clarified by experiments by the present inventors that the Q × f value is greatly reduced when the Bi content is in the above range. Thus, as a result of intensive studies focusing on the amount of Bi and the quantitative relationship between Bi and RE and Ca, the present inventors have reduced the amount of Bi and the ratio of Bi to RE (Bi It was found that a high Q × f value can be realized by setting / RE) within a range determined according to the amount of Ca. Therefore, the content c of Bi in terms of BiO _3/2 needs to be greater than 0 mol% and less than 8 mol% and satisfy 0 ≦ c / d ≦ a × 0.06.

  The amount of Bi is preferably 0.5 mol% or more and less than 8 mol%, and more preferably 1 to 5 mol%, from the viewpoint of a balance between a high Q × f value and a high relative dielectric constant εr.

The rare earth element RE in the oxide dielectric contributes to control of the temperature change coefficient τf of the resonance frequency, and as the RE amount increases, τf increases in absolute value in the negative direction. On the other hand, if the amount of RE decreases too much, the Q × f value decreases. Therefore, the amount (d) of REO _3/2 needs to satisfy 2.5 ≦ d ≦ 25.

Of the components constituting the oxide dielectric, in REO _3/2 , RE is preferably Nd, and a part thereof is a lanthanide group element (La, Ce, Pr, Sm, Y, Yb). , Dy or one or more selected from Dy). By setting RE to Nd, the relative dielectric constant εr, Q × f value and temperature characteristics (temperature stability) are well balanced, and the balance between characteristics and material cost is also good. Further, by substituting a part of Nd with an element having an ionic radius larger than Nd, such as La, Ce, or Pr, the relative dielectric constant εr can be further increased. By substituting a part of Nd with an element having an ion radius smaller than Nd, such as Sm, Y, Yb, or Dy, the Q × f value can be further increased.

When there is too much Ti, a different phase containing a large amount of Ti such as TiO ₂ is likely to be generated due to excessive Ti more than necessary for the formation of the perovskite crystal phase. On the other hand, if the Ti content is too small, a heterogeneous phase containing a large amount of other metal elements that should enter the A site of the perovskite tends to be generated. In either case, there is a possibility that the characteristics are greatly deteriorated due to the occurrence of a different phase. Therefore, the content e of Ti in terms of TiO ₂ needs to be 50 mol% or more and 60 mol% or less.

In the above-described oxide dielectric, it is necessary to control the molar ratio b / (c + d) between the monovalent element Li and the sum of the trivalent element Bi and the rare earth element RE within an appropriate range. By setting b / (c + d) <1, an oxide dielectric having a substantially single-phase perovskite structure can be obtained. When b / (c + d) ≧ 1, the relative dielectric constant εr decreases due to the generation of a heterogeneous phase composed of Li ₂ O.TiO ₂ . On the other hand, when Li becomes too small, that is, b / (c + d) <0.65, a heterogeneous phase such as Bi ₂ Ti ₂ O ₇ or Bi ₄ Ti ₃ O ₇ is generated, and thereby the relative dielectric constant εr and The Q × f value decreases and the absolute value of the temperature change coefficient τf in the positive direction increases. Therefore, by setting 0.65 ≦ b / (c + d) <1, a high-quality oxide dielectric is realized.

In the above oxide dielectric, in the above formula (1), b and d are the following formulas:
b / d ≧ 0.90
It satisfies.
When b and d are in a relationship satisfying b / d ≧ 0.90, the oxide dielectric contains an excess of Li that can react with Bi. Since the sintering proceeds while producing a low melting point compound such as LiBiO ₂ (melting point is about 700 ° C.), low temperature firing can be achieved. Therefore, by satisfying this requirement, for example, even when the firing temperature is less than 1200 ° C., the density of the sintered body can be improved and the relative dielectric constant εr can be increased.

In the above oxide dielectric, a, b, d, and e in the above formula (1) are represented by the following formula:
(A + b + d) / e <1.0
It satisfies.

a, b, d, e are the following formulas:
(A (Ca) + b (Li) + d (RE)) / e (Ti) <1.0
When it satisfies, it becomes easy to increase the relative dielectric constant εr when Bi is added. In the oxide dielectric having a perovskite structure, the molar ratio A / B of A site atoms to B site atoms is greatly related to the dielectric characteristics. In the oxide dielectric contained in the dielectric ceramic composition of the present invention, A / B smaller than 1 is suitable for reducing the occurrence of heterogeneous phases and improving the characteristics. The A site is mainly composed of Ca, Li, and RE, the B site is mainly composed of Ti, and Bi is mainly coordinated to the A site. However, in the present oxide dielectric, as a premise for improving the relative dielectric constant εr by adding Bi, it is necessary to have a good dielectric property with a composition in which a different phase is not generated even in a composition excluding Bi. Even in the composition except for Bi, A / B <1.0 is necessary to improve the characteristics. Therefore, as described above, a, b, d, and e in the formula (1) are represented by the following formula:
(A (Ca) + b (Li) + d (RE)) / e (Ti) <1.0
It is necessary to satisfy.

In the above oxide dielectric, the molar ratio A / B of the A-site atom to the B-site atom in the perovskite structure, that is, (a + b + c + d) from the viewpoint of reducing the amount of precipitation of heterogeneous phase and improving the characteristics. / E needs to be within an appropriate range. In the oxide dielectric, since it is considered that some vacancies are formed at the A site, it is preferable that A / B is smaller than 1 for the reduction of different phases and the improvement of characteristics as will be described later. That is, if (a + b + c + d) / e ≧ 1, a heterogeneous phase is generated, which may cause a decrease in relative permittivity εr and Q × f value. In addition, even when the molar amount A of atoms at the A site is too small compared with the molar amount B of atoms at the B site, the occurrence of a heterogeneous phase may cause a decrease in the relative dielectric constant εr and the Q × f value. Therefore, as a result of detailed analysis of the results of characteristic evaluation and structural analysis of the obtained dielectric by the inventors changing the composition of each element in various ways, the desirable range of (a + b + c + d) / e is (a + b + c + d). ) / E <1.0. Note that if the B-site atom has too much Ti, a heterogeneous phase containing a large amount of Ti such as TiO ₂ is likely to be generated, and the dielectric properties are lowered, so that (a + b + c + d) / e is preferably 0.93 or more. .

  In order for the dielectric ceramic to have a high Q × f value, not only simply reducing the Bi amount or increasing the RE amount, but also changing the molar ratio (c / d) between the Bi amount and the RE amount according to the Ca amount. It is necessary to control. That is, this c / d is set within a range having an upper limit of a value obtained by multiplying the molar ratio (a) of Ca by 0.06. When this upper limit is exceeded, the Q × f value is significantly lowered. It is more preferable that the upper limit is a value obtained by multiplying the molar ratio of Ca by 0.04 because a dielectric ceramic composition having a higher Q × f value can be realized.

[Method of manufacturing dielectric ceramic]
The dielectric ceramic can be manufactured, for example, according to the manufacturing process shown in FIG. FIG. 1 shows a series of manufacturing processes from the production of an oxide dielectric to the production of a dielectric ceramic, and includes a mixing step 1, a preliminary firing step 2, a pulverizing step 3, a granulating step 4, a forming step 5, And a firing step 6. The oxide dielectric powder is produced by the steps from the mixing step 1 to the pulverizing step 3 in the manufacturing process shown in FIG.

  In the production of the oxide dielectric, first, a predetermined amount of raw material powder is weighed and mixed (mixing step 1). As the raw material powder of the main component, oxide powders and compounds that become oxides upon heating, such as carbonates, hydroxides, oxalates, nitrates, and the like can be used. In this case, not only one kind of metal oxide (compound) but also a composite oxide powder containing two or more kinds of metals may be used as the raw material powder. What is necessary is just to select the average particle diameter of each raw material powder suitably in the range of 0.1 micrometer-3.0 micrometers, for example.

As a mixing method, for example, wet mixing using a ball mill or the like can be employed. After mixing, drying, pulverization, and sieving are performed, and the pre-baking step 2 is performed. In the calcination step 2, for example, an electric furnace or the like is used, and the calcination is performed by maintaining the temperature in a temperature range of 900 ° C. to 1200 ° C. for a predetermined time. The atmosphere at this time may be a non-reducing atmosphere such as O ₂ , N ₂ or air. Moreover, what is necessary is just to select the said holding time in calcination suitably in the range of 0.5 to 5.0 hours, for example.

  After calcination, in the pulverization step 3, the calcined body is pulverized until the average particle size becomes about 0.1 μm to 2.0 μm, for example. As the pulverizing means, for example, a ball mill or the like can be used.

  In addition, the timing which adds the raw material powder of each component is not limited only to the said mixing process 1. For example, only raw material powders of some of the necessary raw material powders are weighed, mixed, and calcined. After pulverizing this, a predetermined amount of raw material powders of other components may be added and mixed.

  In order to manufacture a dielectric ceramic, the dielectric ceramic composition obtained as described above is granulated in the granulating step 4, and the granulated granule in the molding step 5 is molded to form a desired shape. After obtaining the body, the molded body is fired in firing step 6. In granulation, it is desirable to add a small amount of an appropriate binder such as polyvinyl alcohol (PVA) or acrylic resin. In addition, the particle size of the obtained granule is desirably about 80 μm to 200 μm.

  In the molding step 5, for example, granules granulated at a pressure of 100 MPa to 300 MPa are pressure molded to obtain a molded body having a desired shape. In the firing step 6, the obtained molded body is heated and held at a predetermined temperature and time, and the binder added at the time of molding is removed to obtain a sintered body. Thus, a dielectric ceramic can be obtained.

The firing temperature can be performed, for example, under a temperature condition of about 1000 ° C. to 1200 ° C., which is lower than the melting point (1230 ° C.) of the Ag (70) -Pd (30) alloy. The firing atmosphere in the firing step 6 may be a non-reducing atmosphere such as O ₂ , N ₂ or air. The heating and holding time may be appropriately selected within a range of 0.5 to 6 hours, for example.

  The dielectric ceramic composition of the present invention can realize a dielectric ceramic having excellent dielectric properties in a well-balanced manner with respect to the relative dielectric constant εr, the Q × f value, and the temperature change coefficient τf (−40 ° C. to 85 ° C.) of the resonance frequency. Even if it is simultaneously fired with the inner conductor material made of an Ag—Pd alloy, the sinterability is good.

  Therefore, the dielectric ceramic composition of the present invention constitutes a resonator for high frequency, particularly microwaves, and uses a laminated dielectric filter (A band-pass filter, a low-pass filter, a high-pass filter) using an Ag—Pd alloy as an internal conductor material. Furthermore, it is suitable for obtaining a dielectric layer of a multilayer component such as a multilayer circuit board having a configuration that functions as a dielectric filter.

  Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

As a raw material powder for producing a dielectric ceramic composition , high-purity CaCO ₃ , Li ₂ CO ₃ , Bi ₂ O ₃ , Nd (OH) ₃ , TiO ₂ , BaCO ₃ , SrCO ₃ , La [OH] _{3 and the} like are prepared. did. The average particle sizes of the raw material powders CaCO ₃ , Li ₂ CO ₃ , Bi ₂ O ₃ , Nd (OH) ₃ , and TiO ₂ are 0.5 μm, 1.0 μm, 1.0 μm, 0.9 μm, and 0.6 μm, respectively. Met.

  A predetermined amount of these raw material powders were weighed and wet mixed in ion-exchanged water for 16 hours using a ball mill. The obtained slurry was sufficiently dried, and then calcined at 1000 ° C. for 4 hours in the air to obtain a calcined body. The obtained calcined body is wet pulverized in ion-exchanged water using a ball mill so that the average particle diameter is in the range of 0.5 to 1.5 μm, and dried to obtain a pulverized calcined powder. It was. The average particle size was measured with a laser diffraction type particle size distribution measuring device (MICROTRAC model 9320-X100, manufactured by Nikkiso Co., Ltd.).

  Thereafter, an acrylic resin was added as a binder to the calcined powder and granulated, followed by press molding at a pressure of 150 MPa to obtain a cylindrical molded body. The molded body was fired at 1150 ° C. for 2 hours and processed to obtain a cylindrical sintered body sample (dielectric ceramic) having a diameter: height = 2: 1. At this time, a conductor paste made of an Ag (70) -Pd (30) alloy was applied to the surface of the molded body and fired at the same time. However, the melting of the Ag-Pd alloy occurred in any composition. There wasn't.

The composition of the obtained cylindrical sintered body sample was confirmed, and the relative density and dielectric characteristics (relative permittivity εr, Q × f value, temperature change coefficient τf of resonance frequency f ₀ ) were measured. The results are shown in Tables 3 and 4.

The composition was confirmed with a fluorescent X-ray analyzer (manufactured by Rigaku Corporation, ZSX-100e) and an inductively coupled plasma emission spectrometer (ICP-AES) apparatus (ICPS-8000, Shimadzu Corporation). Tables 1 and 2 show a list of the produced oxide dielectric ceramics. In Table 2, for D1 to D7, the “replacement” column on the right side of CaO is blank, which means that part of Ca is not replaced by Ba, Sr, Mg, or the like. To express. As for D8 to D10, the right column of REO _3/2 is blank. This is because all of RE is Nd, and part of RE is La, Ce, Pr, Sm, Dy, It is not substituted by Yb, Y or the like.

  The relative density is a measure of the sinterability of the dielectric ceramic composition. The higher the density, the higher the sinterability, and the lower the density, the lower the sinterability. The relative density was calculated assuming that the density of the sample with the highest density among the densities of the sintered body samples fired at 1000 to 1400 ° C. for 2 hours was 100%.

Dielectric characteristics were measured by the Hakki-Coleman method. The measuring instruments used were a network analyzer (manufactured by Hewlett-Packard Company, 8510C) and a constant temperature bath (manufactured by Death Patch Company, 900 series). The resonance frequency at the time of measurement is 3-5 GHz, measurement of the temperature characteristic is, in the range of -40 to + 85 ° C., was calculated by the following equation to the resonance frequency _f 0 (+ 20 ℃) relative to the + 20 ° C..
τf = {[f ₀ (+ 85 ° C.) − f ₀ (−40 ° C.)] / [f ₀ (+ 20 ° C.) × (85 + 40)]} × 10 ⁶ (ppm / K)

  In Tables 3 and 4, when the relative density is 95% or more, the dielectric constant εr of the dielectric ceramic is 95 or more, the Q × f value is 1500 GHz or more, and the absolute value of τf is smaller than 250 ppm / K, The relative permittivity and Q × f value are large, and the temperature stability of the resonance frequency is good. If it has a dielectric characteristic exceeding this standard, it can function effectively as a dielectric layer of a dielectric filter.

As shown in Tables 3 and 4, in the dielectric ceramics of Reference Examples 1 to 36 and Examples 1 to 3 , all of the relative density, relative permittivity εr, Q × f value, and absolute value of τf satisfy the above-mentioned standard. I met. However, in Comparative Examples 1 to 16, at least one of the relative density, the relative permittivity εr, the Q × f value, and the absolute value of τf did not satisfy the above criteria.

Therefore, it is considered that the dielectric ceramics obtained by firing the dielectric ceramic compositions of Reference Examples 1 to 36 and Examples 1 to 3 can effectively function as the dielectric layers of the dielectric filter. On the other hand, it is considered that the dielectric ceramics obtained by sintering the dielectric ceramic compositions of Comparative Examples 1 to 16 are difficult to function effectively as the dielectric layer of the dielectric filter.

  As described above, according to the dielectric ceramic composition of the present invention, the relative dielectric constant εr and Q × f can be obtained even when fired at a temperature that can be fired simultaneously with the inner conductor made of the Ag—Pd alloy, for example, at a temperature of 1200 ° C. or less. It was confirmed that a dielectric ceramic having a large value and good temperature stability of the resonance frequency can be realized.

It is a flowchart which shows an example of the manufacturing process of the dielectric material ceramic which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Mixing process, 2 ... Temporary baking process, 3 ... Crushing process, 4 ... Granulation process, 5 ... Molding process, 6 ... Baking process.

Claims (1)

A dielectric ceramic composition comprising an oxide dielectric represented by the following composition formula (1).
_{a · CaO-b · LiO 1/2} -c · BiO 3/2 -d · REO 3/2 -e · TiO 2 ... (1)
[However, in the above formula (1), RE represents at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Dy, Yb and Y, and includes at least Nd. In the RE, a part of the Nd, La, Ce, is substituted by at least one P r, S m, Dy, is selected from the group consisting of Yb, and Y. In the above formula (1), a part of Ca is substituted with at least one selected from the group consisting of Ba, Sr and Mg. Further, a to e represent the ratio (mol%) of each component,
4 ≦ a ≦ 26
10 ≦ b ≦ 23
0 <c <8
2.5 ≦ d ≦ 25
50 ≦ e ≦ 60
0.65 ≦ b / (c + d) <1.0
b / d ≧ 0.93
(A + b + d) / e <1.0
0 <c / d ≦ a × 0.04
a + b + c + d + e = 100
0.93 ≦ (a + b + c + d) / e <1.0
Satisfy the relationship. ]