JP3393764B2 - Dielectric porcelain composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic composition having a high Q value in a high frequency region such as microwave and millimeter wave, and is used in a high frequency region such as microwave and millimeter wave. The present invention relates to a dielectric ceramic composition which can be used for various resonator materials, MIC dielectric substrate materials, dielectric waveguide materials, laminated ceramic capacitors and the like.

[0002]

2. Description of the Related Art Conventionally, dielectric porcelain has been widely used in dielectric resonators, MIC dielectric substrates, waveguides, etc. in a high frequency range such as microwaves and millimeter waves.

Conventionally, as a dielectric ceramic of this type,
For example, the one disclosed in JP-A-57-69607 is known. The dielectric porcelain disclosed in this publication has a composition ratio of BaO.xTiO ₂ based on a molar ratio of 1 to 100 parts by weight of a composition of 3.9 ≦ x ≦ 4.1.
~ 26 parts by weight of ZnO is added.

In such a dielectric ceramic, the relative permittivity is 3
0 to 40, the Q value at the measurement frequency f = 3.5 [GHz] is about 4500 (Qf = 15750 [GHz]), and the temperature coefficient τf of the resonance frequency is −25 to +2.
It can be controlled within the range of 5 [ppm / ° C.].

However, the above-mentioned Japanese Patent Laid-Open No. 57-69.
The dielectric ceramic disclosed in Japanese Patent No. 607 has a Qf value of 15
It is about 750 [GHz], which is still low, and there is a problem that the temperature coefficient τf of the resonance frequency is bent, that is, the linearity of the temperature drift is low.

As a solution to such a problem, the one disclosed in Japanese Patent Laid-Open No. 61-10806 is known. The dielectric ceramic composition disclosed in this publication is about 1 to 25 parts by weight of ZnO and about 1.5 to 6 parts by weight with respect to 100 parts by weight of the composition represented by the general formula BaTi ₄ O _9. Ta ₂ O ₅ is added and mixed, and as a characteristic, Δfr representing the temperature drift characteristic can be controlled to near zero, and at the measurement frequency of 13 GHz, Δfr is a dielectric loss tan δ near zero. 3.65-
It can be set to 3.86 × 10 ⁻⁴ (Qf value 33700 to 36000).

[0007]

However, in the dielectric ceramic disclosed in Japanese Patent Laid-Open No. 61-10806, the Qf value when the temperature drift characteristic is near zero is 33700.
In recent years, the operating frequency has become higher and the high-precision control is required even with respect to temperature change. Therefore, there is a problem that the Qf value near the zero temperature drift characteristic is still low. there were.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that in the Ba—Ti based dielectric ceramic composition, part of Ba is replaced with Sr, and By containing a predetermined amount of Cu or Cu and Zn, the relative dielectric constant is 30 to 40 and the Qf is 41000 [G
Hz] or more and the temperature coefficient τf of the resonance frequency is -20
To +20 [ppm / ° C.] and the bending (temperature drift) of the temperature coefficient τf of the resonance frequency is −2 to +2.
It is possible to control in the range of [ppm / ° C.] (−40 to 85 ° C.), and it is possible to set the Qf value in the vicinity of zero of Δτf representing the temperature drift characteristic to a high Qf value of 42000 or more, particularly about 52000. The inventors have found what they can do and have reached the present invention.

That is, the dielectric ceramic composition of the present invention is a metal
As elements Ba, Ti, Sr, Cu, inevitable
A dielectric porcelain composition consisting of a pure substance and having a composition formula based on the molar ratio of metal element oxides is (Ba _1-a Sr _a ) O.x
When expressed as TiO ₂ , a and x are 0.01 ≦ a ≦
0.08, 3.9 ≤ x ≤ 4.1, and with respect to 100 parts by weight of the main component, Cu was converted to CuO in terms of CuO.
The content is 01 to 7 parts by weight. In addition, the present invention
The electric porcelain composition has Ba, Ti, and S as metal elements.
Dielectric composed of r, Cu, Zn, and unavoidable impurities
A porcelain composition, which is based on a molar ratio of metal element oxides
When the formula is expressed as (Ba _1-a Sr _a ) O · xTiO ₂ ,
Where a and x are 0.01 ≦ a ≦ 0.08 and 3.9 ≦ x ≦
4.1 against a main component satisfying 4.1 and 100 parts by weight of the main component
Then, 0.01 to 7 parts by weight of Cu in terms of CuO and 18 parts by weight or less of Zn in terms of ZnO are contained .

[0010]

In the dielectric ceramic composition of the present invention, the composition formula (Ba
_1-a Sr _a ) In the Ba-Ti-based dielectric ceramic composition represented by O · xTiO ₂ , a part of Ba is replaced with a predetermined amount of Sr, and Cu or Cu and Zn are contained in a predetermined amount. Therefore, the relative permittivity is 30 to 40 and the Qf is 41.
000 [GHz] or more, and the temperature coefficient τf of the resonance frequency is -20 to +20 [pp in the temperature range of -40 to 85 ° C.
m / ° C] and the bending (temperature drift) of the temperature coefficient τf of the resonance frequency can be controlled within the range of -2 to +2 [ppm / ° C], and Δτf representing the temperature drift characteristic is Qf value near zero is 42000 or more,
Particularly, it can be set to about 52000.

That is, in the present invention, by containing Cu, it is possible to promote an increase in the relative dielectric constant, an improvement in the Qf value, a decrease in τf, and further, a significant reduction in the firing temperature (about 100 ° C.). it can. Further, by containing Cu, the bending (temperature drift) of the temperature coefficient τf of the resonance frequency can be controlled in the range of −2 to +2 [ppm / ° C.], and the linearity of the temperature drift can be improved. it can.

Further, by substituting a part of Ba with Sr, the Qf value can be greatly improved to 42000 or more, and at the same time, the coarsening of the crystal grains is suppressed to improve the reduction resistance and It is possible to suppress a decrease in Qf value due to an increase in size. Furthermore, since the ionic radii of Sr and Ba are different, lattice distortion occurs by substituting a part of Ba with Sr, and as a result, the strength of the porcelain can be improved.

Further, by further containing Zn, the Qf value can be improved and the temperature coefficient τf of the resonance frequency can be shifted from the plus side to the minus side.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The dielectric ceramic composition of the present invention comprises B
In the a-Ti-based dielectric ceramic composition, part of Ba is S
It is substituted with r and contains a predetermined amount of Cu or Cu and Zn.

The compositional formula based on the molar ratio is (Ba _1-a S
When expressed as r _a ) O · xTiO ₂ , a is 0.01 ≦ a ≦
The reason for setting it in the range of 0.08 is that by substituting a part of Ba with Sr, the Qf value can be significantly improved and the porcelain strength can be improved.
This is because when the substitution amount a of Ba by Sr is smaller than 0.01, the effect of improving the Qf value is small and the effect of improving the mechanical strength of the porcelain is small. On the other hand, a is 0.08
This is because if it becomes larger than the above, the solid solution limit amount of Sr will be exceeded, a crystal phase containing Sr will be precipitated, and the Qf value will decrease. Ba
The substitution amount a of Sr with Sr is preferably 0.01 to 0.05 from the viewpoint of high Qf value and improvement of mechanical strength.

In the above composition formula, x is 3.9≤x≤
The reason why it is within the range of 4.1 is that a high Qf value can be maintained within this range. When the value of x is smaller than 3.9 or larger than 4.1, the Qf value decreases. From the viewpoint of high Qf value, the value of x is preferably 3.95 or more and 4.05 or less.

Further, the Cu content is 0.01 to 7 parts by weight in terms of CuO with respect to 100 parts by weight of the main component.
Is less than 0.01 parts by weight or more than 7 parts by weight in terms of CuO, the bending of the temperature coefficient τf of the resonance frequency becomes larger than 2 [ppm / ° C], which is not practical. . From the viewpoint of making the bending of the temperature coefficient τf close to 0, it is desirable that Cu is contained in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the main component in terms of CuO.

Further, in the present invention, the main component 100
It is desirable that zinc is contained in an amount of 18 parts by weight or less in terms of ZnO with respect to parts by weight, but 18 parts by weight or less of zinc in terms of ZnO is included in 100 parts by weight of the main component. This is because the temperature coefficient τf of the resonance frequency becomes smaller than −20 [ppm / ° C.] when it is too large, which is not practical. From the viewpoint of making the temperature coefficient τf of the resonance frequency closer to 0, the content of zinc is 1
It is desirable to contain 4 to 18 parts by weight, especially 8.7 to 13.9 parts by weight in terms of ZnO with respect to 00 parts by weight.

The dielectric ceramic composition of the present invention has the following compositional formula: 0.01 ≦ a ≦ 0.05, 3.95 ≦ x ≦
It is 4.05, and it is desirable that zinc is added in an amount of 8.7 to 13.9 parts by weight in terms of ZnO and 0.1 to 5.0 parts by weight in terms of CuO based on 100 parts by weight of the main component. . In this case, the Qf value is 49000 [GHz] or more, and the temperature coefficient τf of the resonance frequency is −12 to +5 [ppm]
/ ° C], the bending (temperature drift) of the temperature coefficient τf of the resonance frequency can be controlled within the range of -1.0 to +2.0 [ppm / ° C], and the temperature coefficient τf of the resonance frequency can be controlled.
The Qf value in the vicinity of zero, that is, Δτf representing the temperature drift characteristic, can be set to 49000 or more, particularly about 55000.

Further, the dielectric ceramic composition of the present invention contains B
When the aTi ₄ O ₉ crystal phase exists as the main crystal phase and Zn is contained, the Ba ₃ Ti ₁₂ Zn ₇ O ₃₄ crystal phase is uniformly dispersed in the porcelain. Other crystals may be slightly precipitated. Then, it is desirable that Sr is solid-dissolved in the BaTi ₄ O ₉ crystal phase and the Ba ₃ Ti ₁₂ Zn ₇ O ₃₄ crystal phase. This Sr is BaTi ₄ O ₉ and B
It replaces a part of Ba in the a ₃ Ti ₁₂ Zn ₇ O ₃₄ crystal phase. In the present invention, the Qf value can be improved and the temperature coefficient τf can be controlled from the positive side to the negative side by precipitating the Ba ₃ Ti ₁₂ Zn ₇ O ₃₄ crystal phase.

The dielectric porcelain composition of the present invention contains, for example, BaCO ₃ , TiO ₂ , SrCO ₃ and Z as raw material powders.
nO and CuO powders were prepared, weighed so that the sintered body had the above-mentioned composition ratio, pulverized and mixed with, for example, ZrO ₂ balls, and the mixed powder was calcined, and then Zr was again used.
The mixture is crushed and mixed with O ₂ balls, and the calcined powder is molded into a predetermined shape by a known method such as press molding or doctor blade method, and then 1050 in air or oxygen atmosphere.
It is obtained by firing at ˜1300 ° C. for 1 to 10 hours.

As the raw material powder, a metal salt such as a hydroxide, a carbonate or a nitrate which produces an oxide by firing may be used.
In the dielectric porcelain of the present invention, as an unavoidable impurity, A
1, Si, Ca, Mg, Fe, Hf, Sn, etc. may be included. CuO may be added after calcination.

In the dielectric ceramic composition of the present invention, BaTi
₄ O ₉ uniformly dispersing Ba ₃ Ti ₁₂ Zn ₇ O ₃₄ crystalline phase in the crystal phase, BaTi ₄ O ₉ crystal phase, Ba ₃ Ti ₁₂ Zn
_In order to form a solid solution of Sr in the ₇ O ₃₄ crystalline phase,
It is necessary to calcine at a temperature of 0 to 1150 ° C. for 6 hours or more. The reason is that the calcination at a temperature lower than 1050 ° C. for less than 6 hours makes it difficult to form the Ba ₃ Ti ₁₂ Zn ₇ O ₃₄ crystal phase.

[0024]

[Example] BaCO ₃ , T having a purity of 99% or more as a raw material
Using powders of iO ₂ , SrCO ₃ , ZnO and CuO,
ZrO was weighed so that the a, x, Zn and Cu contents of the above compositional formula would be the ratios shown in Table 1, and pure water was used as the medium.
Wet mixing was carried out for 20 hours on a ball mill using _two balls. The mixture is then dried (dehydrated) and dried at 1100 ° C for 6
I calcined for an hour. This calcined product was crushed and used as a sample for dielectric property evaluation in a cylindrical shape having a diameter of 10 mm and a height of 8 mm and 1 ton.
Press-molded at a pressure of / cm ² and fired in the air at the temperature shown in Table 1 for 2 hours to give a diameter of 8 mm and a height of 6 m.
A columnar sample of m was obtained.

The dielectric properties were evaluated by measuring the relative permittivity and Q value at a frequency of 6 GHz by the dielectric cylinder resonator method using the above sample. The value represented by the product of the Q value and the measurement frequency f is shown in Table 1. Further, the resonance frequency in the temperature range of -40 to 85 ° C was measured, and the temperature coefficient τf of the resonance frequency was calculated based on the resonance frequency at 25 ° C.

In Table 1, τf ₁ is the temperature coefficient of the resonance frequency at -40 ° C, and τf ₂ is the temperature coefficient of the resonance frequency at 85 ° C. Where τf ₁ =
_{[(F -40 -f 25) /} f 25] / 65 × 10 6 [ppm /
_{℃], τf 2 = [(} f 85 -f 25) / f 25] / 60 × 10
⁶ Calculated based on [ppm / ° C]. f- ₄₀ is -40
Is a resonance frequency at 85 ° C., f ₈₅ is a resonance frequency at 85 ° C., and f ₂₅ is a resonance frequency at 25 ° C. Further, the curve Δτf (temperature draft) of the temperature coefficient of the resonance frequency is obtained from the equation Δτf = τf ₁ −τf ₂ ,
The results are shown in Table 1.

[0027]

[Table 1]

From Table 1, in the sample of the present invention, the relative permittivity is 35 or more, the Qf value is 41000 [GHz] or more, the temperature coefficient τf of the resonance frequency is ± 20 [ppm / ° C], and , Bending of temperature coefficient τf of resonance frequency Δτf
Has excellent characteristics of -2 to +2 [ppm / ° C]. Further, it can be seen that the Qf value in the vicinity of the bending Δτf of the temperature coefficient of the resonance frequency is zero can be set to a high Qf value of 43,000 or more, particularly about 55,000.

Then, in the samples of the present invention except the sample No. 4, the BaTi ₄ O ₉ crystal phase and the Ba ₃ Ti ₁₂ Zn ₇ O were used.
₃₄ crystal phases were contained, and as a result of analyzing these crystal phases with an X-ray microanalyzer (EPMA), it was confirmed that Sr was in solid solution.

Further, according to Samples Nos. 4 to 9, it is understood that as the Zn content increases, Qf increases, the temperature coefficient τf of the resonance frequency can shift to the negative side, and Δτf approaches 0. .

Further, according to Sample Nos. 22 to 29, Cu
It can be seen that in the case of the amount of the present invention, the Qf value increases more than in the case where the amount is out of the range, the temperature coefficient τf of the resonance frequency can shift to the negative side, and Δτf approaches 0.

[0032]

As described above in detail, according to the present invention, B
In the a-Ti-based dielectric ceramic composition, part of Ba is S
By substituting with r and containing a predetermined amount of Cu or Cu and Zn, the relative dielectric constant is 30 to 40, Qf is 41000 [GHz] or more, and the temperature coefficient τf of the resonance frequency is -20 to +20 [. ppm / ° C] and the bending of the temperature coefficient τf of the resonance frequency is -2 to +2.
The value can be set within the range of [ppm / ° C.], and the Qf value when the bending Δτf of the temperature coefficient of the resonance frequency is near zero is 4
1000 or more, further improving the strength of the porcelain, various resonator materials used in frequency regions such as microwaves and millimeter waves, dielectric substrate materials for MIC, and dielectric waveguide materials And so on.

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Claims (2)

(57) [Claims] 1. A metal element containing Ba, Ti, Sr,
A dielectric ceramic composition comprising Cu and inevitable impurities.
When the composition formula based on the molar ratio of the metal element oxide is expressed as (Ba _1-a Sr _a ) O.xTiO ₂ , the a and x are 0.01 ≦ a ≦ 0.08 3.9. For a main component satisfying ≦ x ≦ 4.1 and 100 parts by weight of the main component,
A dielectric ceramic composition containing 0.01 to 7 parts by weight of Cu in terms of CuO. 2. Ba, Ti, Sr as metal elements,
Dielectric porcelain set consisting of Cu, Zn, and unavoidable impurities
When the composition formula of the composition is expressed as (Ba _1-a Sr _a ) O · xTiO ₂ by the molar ratio of the metal element oxide , a and x are 0.01 ≦ a ≦ 0.08 For a main component satisfying 3.9 ≦ x ≦ 4.1 and 100 parts by weight of the main component,
0.01 to 7 parts by weight of Cu in terms of CuO, Zn as ZnO
A dielectric ceramic composition containing 18 parts by weight or less in terms of conversion.