JPH11111056A - Dielectric ceramic composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide dielectric ceramic composition capable of miniaturizing high frequency electronic parts and substrates and stabilizing their characteristics. SOLUTION: This composition is a compound oxide containing Mg,Ca,Ti as metal elements. It contains: a main component represented by a formula of aMgO.bCaO.cTiO2 based on weight ratio of the metal element oxides, where 23.0<=a<=31.0, 1.5<=b<=9.0, 60.0<=c<=70.0, a+b+c=100; 3-20 pts.wt. of B-containing compound in terms of B2 O3 p; 1-10 pts.wt. of an alkali metal- containing compound in terms of an alikali metal carbonate; and 0.5-6.0 pts.wt. of at least one sort of Ta-containing compound and Nd-containing compound in terms of Ta2 O3 , Nd2 O3 , respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dielectric porcelain composition, and more particularly to a dielectric porcelain composition suitable for electronic parts such as resonators, capacitors, filters, etc., and substrates incorporating them.

[0002]

2. Description of the Related Art Hitherto, various dielectric ceramics have been used as dielectric materials for electronic components such as resonators, capacitors, filters, and the like, and substrates incorporating these components. And
In recent years, with the development and spread of mobile communication such as mobile phones, demand for dielectric ceramics as materials for electronic circuit boards and electronic components has been increasing.

[0003] When simultaneously firing dielectric ceramics and internal conductors in electronic parts and substrates, the firing temperature of conventional dielectric ceramics was as high as 1100 ° C or higher. Certain Pt, Pd, W, Mo, etc. have been used. Since these high-melting-point conductor materials have high conduction resistance, there have been problems in conventional electronic components and substrates such that the Q value of the resonance circuit and inductance is reduced, and the transmission loss of the conductor line is increased.

[0004] In order to solve such a problem, there has been proposed a low-temperature-fired dielectric ceramic which can be co-fired with Ag, Cu or the like having a low conduction resistance. For example, the dielectric porcelain composition disclosed in Japanese Patent Application Laid-Open No. 8-208330, filed by the present applicant, contains MgO, CaO, and TiO _2.
And B ₂ O ₃ , Li ₂ CO ₃ , and 900
It could be fired simultaneously with the internal conductor such as Ag or Cu at a relatively low temperature of -1050 ° C.

[0005]

However, in the dielectric porcelain composition disclosed in Japanese Patent Application Laid-Open No. 8-208330, when the relative dielectric constant εr is 20 or more, the temperature coefficient τf of the resonance frequency increases to the plus side. It has been difficult to simultaneously satisfy the two requirements of miniaturization of high-frequency electronic components and substrates and stabilization of characteristics.

[0006] The present invention has been made in view of the above problems,
In a composition having a large relative dielectric constant εr of the dielectric ceramic composition, the temperature coefficient τf of the resonance frequency can be stabilized to a value close to 0, and the miniaturization of high-frequency electronic components and substrates and the stabilization of characteristics can be realized. It is an object of the present invention to provide a dielectric ceramic composition that can be used.

[0007]

The dielectric porcelain composition of the present invention is a composite oxide containing Mg, Ca and Ti as metal elements, and has a composition formula based on the weight ratio of these metal element oxides. , AMgO · bCaO · cTiO ₂ , a, b, c are 23.0 ≦ a ≦ 31.0, 1.5
≦ a ≦ 9.0, 60.0 ≦ c ≦ 70.0, a + b + c =
100 parts by weight of the main component satisfying 100, and ₃ to 20 parts by weight of the B-containing compound in terms of B ₂ O ₃ with respect to 100 parts by weight of the main component.
Alkali metal-containing compound is converted to alkali metal carbonate by 1
-10 parts by weight, at least one of the Ta-containing compound and the Nd-containing compound was Ta ₂ O ₃ and Nd ₂ O ₃ , respectively.
It contains 0.5 to 6.0 parts by weight in total.

Further, Mg, Ca and T are used as metal elements.
i is a composite oxide having a composition formula (10
_{0-x) MgTiO 3 · xCaTiO} 3 ( however, where x
Represents a weight ratio, and a main component represented by 8 ≦ x ≦ 20);
The B-containing compound was added to B ₂ O with respect to 100 parts by weight of the main component.
₃ to 20 parts by weight in terms of 3; 1 to 10 parts by weight of alkali metal-containing compound in terms of alkali metal carbonate; and at least one of Ta-containing compound and Nd-containing compound in terms of Ta ₂ O ₃ and Nd ₂ O ₃ , respectively. In a total amount of 0.5 to 6.0 parts by weight.

[0009]

According to the dielectric porcelain composition of the present invention, 900 to 10
It can be fired at a relatively low temperature of 50 ° C. and has a relative dielectric constant ε
The r and Q values are high, and the temperature coefficient τf of the resonance frequency can be reduced.

That is, in the dielectric ceramic composition of the present invention, T
at least one of the a-containing compound and the Nd-containing compound
The seeds were converted to Ta ₂ O ₃ and Nd ₂ O ₃ respectively, for a total of 0.5
To 6.0 parts by weight, the relative dielectric constant
As described above, the temperature coefficient τf of the resonance frequency can be controlled within ± 30 ppm / ° C., and the miniaturization of the high-frequency electronic components and the substrate and the stabilization of the characteristics can be realized.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The dielectric ceramic composition of the present invention is a composite oxide containing Mg, Ca and Ti as metal elements, and the composition formula based on the weight ratio of these metal element oxides is aMgO · When expressed as bCaO · cTiO ₂ , a,
b and c are 23.0 ≦ a ≦ 31.0, 1.5 ≦ b ≦ 9.
0, 60.0 ≦ c ≦ 70.0, a + b + c = 100
₃ to 20 parts by weight in terms of ₂ O ₃ , 1 to 10 parts by weight of an alkali metal-containing compound in terms of an alkali metal carbonate, and at least one of a Ta-containing compound and a Nd-containing compound in the form of Ta ₂ O ₃ and Nd ₂ O, respectively. a total of ₃ terms of 0.5 to 6.
0 parts by weight.

In the present invention, the weight ratio a of MgO in the composition formula is 23.0 ≦ a ≦ 31.0, and the weight ratio b of CaO is b
Is set to 1.5 ≦ b ≦ 9.0, and at least one of a Ta-containing compound and a Nd-containing compound is further mixed with Ta ₂ O ₃ and Nd ₂ O with respect to 100 parts by weight of the main component.
_The total content of 0.5 to 6.0 parts by weight in terms of ₃ was Mg
When the weight ratio a of O is less than 23% by weight, when the weight ratio b of CaO exceeds 9% by weight, or when the Ta-containing compound and the Nd-containing compound are less than 0.5 part by weight, the temperature coefficient of the resonance frequency This is because τf becomes too large.

Conversely, when the weight ratio a of MgO exceeds 31% by weight, when the weight ratio b of CaO is less than 1.5% by weight, or when the Ta-containing compound and the Nd-containing compound exceed 6 parts by weight, This is because the relative permittivity εr or the Q value decreases.

Therefore, the weight ratio a of MgO, the weight ratio b of CaO and the amounts of the Ta-containing compound and the Nd-containing compound are 23.0 ≦ a ≦ 31.0 and 1.5 ≦ b ≦ 9.
0, and a total of 0.5 to 6.0 parts by weight. From the viewpoint of improving the temperature coefficient τf of the resonance frequency, the relative dielectric constant εr or the Q value, 23.0 ≦ a ≦ 28.0, 4.0 ≦ b ≦
9.0, preferably 0.5 to 4 parts by weight in total.

Further, the weight ratio c of TiO ₂ is set to 60 ≦ c ≦
The reason for setting it to 70 is that when the weight ratio c of TiO ₂ is less than 60% by weight or more than 70% by weight, the Q value decreases. Therefore, the weight ratio c of TiO ₂ is 60 ≦ c ≦ 7.
0, and especially 64 ≦ c ≦ from the viewpoint of improving the Q value.
68 is preferred.

The starting materials are MgTiO ₃ and CaTi
By using O ₃ , the relative dielectric constant εr and the Q value are further improved, and the control of the temperature coefficient becomes easy. That is, (10
_{0-x) MgTiO 3 · xCaTiO} 3 ( however, where x
Represents a weight ratio, and a main component represented by 8 ≦ x ≦ 20);
The B-containing compound was added to B ₂ O with respect to 100 parts by weight of the main component.
₃ to 20 parts by weight in terms of 3; 1 to 10 parts by weight of alkali metal-containing compound in terms of alkali metal carbonate; and at least one of Ta-containing compound and Nd-containing compound in terms of Ta ₂ O ₃ and Nd ₂ O ₃ , respectively. And 0.5 to 6.0 parts by weight in total.

Here, the weight ratio of CaTiO _{3 in} the main component is set to 8 ≦ x ≦ 20 because the weight ratio of CaTiO ₃ is 8
When the content is less than 10% by weight, the relative dielectric constant εr decreases, and
If the weight ratio exceeds 20% by weight, the temperature coefficient τf of the resonance frequency is greatly shifted to the plus side. Therefore, the weight ratio x of CaTiO ₃ is specified to be 8 to 20% by weight, and particularly preferably 10 to 17% by weight from the viewpoint of improving the temperature coefficient τf of the resonance frequency and the relative dielectric constant εr.

Also, in the present invention,
The B-containing compound is ₃ to 20 parts by weight in terms of B ₂ O ₃ , and the alkali metal-containing compound is 1 to 10 parts by weight in terms of an alkali metal carbonate.
It contains parts by weight. As described above, the B-containing compound is added in an amount of ₃ to 20 in terms of B ₂ O ₃ with respect to 100 parts by weight of the main component.
The addition of parts by weight means that when the addition amount of the B-containing compound is less than 3 parts by weight, sintering does not occur even at 1100 ° C., and Ag or C
This is because simultaneous sintering with u cannot be performed, and when the amount exceeds 20 parts by weight, the crystal phase changes and the Q value decreases. Therefore, the amount of the B-containing compound is B ₂ O
_It is specified as 3 to 20 parts by weight in terms of 3 and 3 to 9 parts by weight is particularly desirable from the viewpoint of improving the Q value.

As the B-containing compound, metallic boron, B ₂ O
₃ , colemanite, CaB ₂ O _{4 and the} like.

The reason why the alkali metal-containing compound is added in an amount of 1 to 10 parts by weight in terms of alkali metal carbonate is that when the amount of the alkali metal-containing compound, for example, the Li-containing compound is less than 1 part by weight, the compound is sintered even at 1100 ° C. Without Ag or C
This is because simultaneous sintering with u becomes impossible, and conversely, if it exceeds 10 parts by weight, the crystal phase changes and the Q value decreases. Therefore, the content of the alkali metal-containing compound is 10
0 parts by weight in terms of alkali metal carbonate, for example, Li
Specified to 1 to 10 parts by weight in terms of ₂ CO ₃ , especially Q
From the viewpoint of improving the value, 3 to 7 parts by weight is desirable.

Examples of the alkali metal include Li, Na and K. Among them, Li is particularly desirable.
Examples of the alkali metal-containing compound include the above-mentioned alkali metal carbonates and oxides.

In the present invention, oxides such as Si, Zn, Mn, and Zr may be added and contained within a range that does not adversely affect the dielectric properties. In this case, firing at a lower temperature becomes possible.

The dielectric porcelain composition of the present invention may be, for example,
Each raw material powder of gCO ₃ , CaCO ₃ , and TiO ₂ was weighed so as to have a predetermined amount, mixed and pulverized.
Calcination is performed in air at a temperature of 300 ° C. for 1 to 3 hours. To the obtained calcined material, for example, each powder of B ₂ O ₃ and Li ₂ CO ₃ ,
And Ta ₂ O ₃ , at least one powder of Nd ₂ O ₃ is weighed to a predetermined amount, mixed and pulverized, and formed into a predetermined shape by a known method such as press molding or a doctor blade method. 900 to 1050 in an oxidizing atmosphere such as the air or a non-oxidizing atmosphere such as a nitrogen atmosphere.
It is obtained by calcining at a temperature of 0.5 to 2.0 hours.

The dielectric ceramic composition of the present invention sometimes contains Al, Fe, Hf, and Sn as inevitable impurities. Further, as the crystal phase, MgTiO ₃ , CaTiO _3
In some cases, (Mg, Ti) ₂ (BO ₃ ) O is deposited with ₃ as the main crystal phase. Further, the average crystal grain size is 2-3 μm.

[0025]

【Example】

Example 1 First, MgCO ₃ , CaCO ₃ , Ti with a purity of 99% or more
Each raw material powder of O ₂ was weighed to the amount shown in Table 1,
Pure water is added as a medium to the raw material powder, and ZrO is added for 24 hours.
After mixing in a ball mill using _two balls, the mixture is dried and then the dried product is dried at 1200 ° C. in air.
For 1 hour.

B ₂ O ₃ , Li ₂ C
O ₃ , Ta ₂ O ₃ , and Nd ₂ O ₃ powders were weighed so as to have the ratios shown in Table 1 and mixed in the ball mill for 24 hours.
% By weight and granulated. The granulated material is press-molded with a pressing force of about 1 t / cm ² to have a diameter of about 12 mm and a height of 10 mm.
Was molded.

Thereafter, the compact was heated at 400 ° C. in the air for 4 hours to remove the binder, and then fired in the air at each temperature shown in Table 2 for 60 minutes. Both end surfaces of the thus obtained cylindrical body were polished to obtain a dielectric property evaluation sample.

The dielectric characteristics were evaluated by using the above-mentioned sample for evaluation by a dielectric cylinder resonator method to set the resonance frequency to 6 to 8 G.
Hz, and the relative dielectric constant εr of each sample and 1 / tan δ at 7 GHz, that is, the Q value were measured.
Temperature coefficient τ of resonance frequency in the temperature range of ~ + 85 ° C
f was measured. These results are shown in Table 2.

[0029]

[Table 1]

[0030]

[Table 2]

According to Tables 1 and 2, the dielectric porcelain composition of the present invention has a relatively low firing temperature of 900 to 1050 ° C., a relative dielectric constant εr of 20 or more, and a Q value at 7 GHz. It can be seen that excellent characteristics having a temperature coefficient τf of 2,000 or more and a resonance frequency within ± 30 can be obtained. For samples Nos. 8 and 9, Na ₂ CO ₃ K ₂ CO ₃ was used instead of Li ₂ CO ₃ as the alkali metal-containing compound.

Example 2 First, raw material powders of MgTiO ₃ and CaTiO _{3 having} a purity of 99% or more were weighed to have the amounts shown in Table 3, and pure water was added as a medium to the raw material powders, and ZrO 3 was added for 24 hours. After mixing in a ball mill using _two balls, the mixture was dried, and then the dried product was calcined in the atmosphere at a temperature of 1200 ° C. for 1 hour.

B ₂ O ₃ , Li ₂ C
O ₃ , Ta ₂ O ₃ , and Nd ₂ O ₃ powders were weighed so as to have the ratios shown in Table 3 and mixed in the ball mill for 24 hours.
% By weight and granulated. The granulated material is press-molded with a pressing force of about 1 t / cm ² to have a diameter of about 12 mm and a height of 10 mm.
Was produced.

Thereafter, the molded body was heated at 400 ° C. for 4 hours in the air to remove the binder, and then calcined at the temperatures shown in Table 4 for 60 minutes in the air. Both end surfaces of the thus obtained cylindrical body were polished to obtain a dielectric property evaluation sample. The dielectric properties were evaluated in the same manner as described above, and the results are shown in Table 4.

[0035]

[Table 3]

[0036]

[Table 4]

According to Tables 3 and 4, in the dielectric ceramic composition of the present invention, the firing temperature is relatively low at 850 to 1050 ° C., the relative dielectric constant εr is 21.5 or more, Value is 3000 or more and temperature coefficient τ of resonance frequency
It can be seen that f has excellent characteristics within ± 20.

[0038]

According to the dielectric ceramic composition of the present invention, when the dielectric ceramic composition has a relative permittivity εr of 20 or more,
The temperature coefficient τf of the resonance frequency can be stabilized to a value close to 0, so that downsizing and stable characteristics of high-frequency electronic components and substrates can be realized.

Claims (2)

[Claims] 1. A composite oxide containing Mg, Ca and Ti as metal elements, when expressed as aMgO · bCaO · cTiO ₂ the formula by weight ratio of the metal element oxides, wherein a, b and c satisfy 23.0 ≦ a ≦ 31.0 1.5 ≦ b ≦ 9.0 60.0 ≦ c ≦ 70.0 a + b + c = 100, and 100 parts by weight of the main component ,
The B-containing compound is ₃ to 20 parts by weight in terms of B ₂ O ₃ , and the alkali metal-containing compound is 1 to 10 parts by weight in terms of an alkali metal carbonate.
Parts, dielectric ceramic characterized by containing a total of 0.5 to 6.0 parts by weight of at least one of each _{Ta 2 O 3, Nd 2 O} 3 in terms of Ta-containing compound and Nd-containing compound Composition. 2. A composite oxide containing Mg, Ca and Ti as metal elements, the composition formula of which is (100-
x) MgTiO ₃ · xCaTiO ₃ (however, where x represents the weight ratio, 8 ≦ x ≦ 20 and main component represented by), with respect to the main component 100 parts by weight, the B-containing compound B ₂ O ₃ to 20 parts by weight in terms of 3; 1 to 10 parts by weight of the alkali metal-containing compound in terms of alkali metal carbonate; and at least one of the Ta-containing compound and the Nd-containing compound, respectively.
_{a 2 O 3, Nd 2 O} 3 dielectric ceramic composition characterized in total 0.5 to 6.0 by containing parts by weight basis.