JP3266484B2 - 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 range such as a microwave and a millimeter wave, and is used in a high frequency range such as a microwave and a millimeter wave. The present invention relates to a dielectric ceramic composition that can be used for various resonator materials, MIC dielectric substrate materials, dielectric waveguide materials, and multilayer ceramic capacitors.

[0002]

2. Description of the Related Art Hitherto, dielectric ceramics have been widely used in dielectric resonators, MIC dielectric substrates, waveguides, and the like in high-frequency regions such as microwaves and millimeter waves.

[0003] Conventionally, as this kind of dielectric porcelain,
For example, one disclosed in JP-A-57-69607 is known. The dielectric porcelain disclosed in this publication is 3.9 ≦ x ≦ 4.0 in BaO-xTiO ₂ .
1 to 26 parts by weight of Z based on 100 parts by weight of the composition
It is obtained by adding nO.

In such a dielectric porcelain, the relative dielectric constant 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 in the range of 5 [ppm / ° C.].

However, the method disclosed in Japanese Patent Application Laid-Open No. 57-69
No. 607 discloses a dielectric porcelain having a Qf value of 15
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, one disclosed in Japanese Patent Application Laid-Open No. S61-10806 is known. The dielectric ceramic composition disclosed in this publication, with respect to the general formula BaTi ₄ 100 parts by weight of the composition represented by O _9, and ZnO of about 1 to 25 parts by weight, from about 1.5 to 6 parts by weight Of Ta ₂ O ₅ is added and mixed. As a characteristic, Δfr representing a temperature drift characteristic can be controlled to be close to zero, and a dielectric loss tan δ where Δfr is near zero at a measurement frequency of 13 GHz. 3.65-
3.86 × 10 ⁻⁴ (Qf value: 33700-36000).

[0007]

However, in the dielectric porcelain disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 61-10806, the Qf value is 33700 when the temperature drift characteristic is near zero.
In recent years, the operating frequency has become increasingly high and the temperature change has to be controlled with high accuracy. In recent years, the problem that the Qf value near the temperature drift characteristic of zero is still low. there were.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, in the Ba-Ti based dielectric porcelain composition, a part of Ba has been replaced with Sr. By adding and containing Zn and Ta in predetermined amounts, the relative dielectric constant is 30 to 40 and Qf is 40000 [GH
z] or more, and the temperature coefficient τf of the resonance frequency is
+15 [ppm / ° C.] and the bending (temperature drift) of the temperature coefficient τf of the resonance frequency is −2 to +2 [p
pm / .degree. C.] (-40 to 85.degree. C.), and it has been found that a Qf value near .DELTA..tau. representing the temperature drift characteristic can be made a high Qf value of 40000 or more. This led to the invention.

[0009] That is, the dielectric ceramic composition of the present invention, at least Ba as the metal element, Ti, contains Sr, the composition formula of these molar _{ratios, (Ba 1-a Sr a} ) O-4
When expressed as TiO ₂ , a is 0.01 ≦ a ≦ 0.08
With respect to 100 parts by weight of the main component satisfying
4 to 18 parts by weight in terms of Ta, 3 to _{5 in} terms of Ta ₂ O ₅
It is contained by weight.

[0010]

According to the dielectric ceramic composition of the present invention, the composition formula (Ba)
In _{1-a Sr a) O-} 4TiO Ba-Ti based dielectric ceramic composition represented by _2, while replacing part of Ba with a predetermined amount of Sr, by a predetermined amount is added containing Zn and Ta Has a relative dielectric constant of 30 to 40 and a Qf of 400
00 [GHz] or more, and the temperature coefficient τf of the resonance frequency in the temperature range of −40 to 85 ° C. is −15 to +15 [ppm
/ ° C] and the bend (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 zero. The Qf value in the vicinity can be set to 40,000 or more.

That is, in the present invention, although the Qf value can be improved to some extent by adding Ta to the main component, the Qf value can be increased to 40,000 or more by replacing a part of Ba with Sr. And can be greatly improved. Further, since the ionic radius of Sr is different from that of Ba, lattice distortion occurs by replacing a part of Ba with Sr, and as a result, the strength of the porcelain can be improved.

Further, by adding Ta to the main component, 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.] Performance can be improved.

The addition of Zn to the main component can also improve the Qf value to some extent, and can shift the temperature coefficient τf of the resonance frequency from plus to minus.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The dielectric porcelain composition of the present invention comprises B
In the a-Ti dielectric ceramic composition, a part of Ba is replaced with S.
In addition to replacing with r, Zn and Ta are added and contained in predetermined amounts. The composition formula based on the molar ratio is represented by (Ba _1-a
When represented as Sr _a ) O-4TiO ₂ , a is 0.01 ≦ a
The reason for setting the value within the range of ≦ 0.08 is that by replacing a part of Ba with Sr, the Qf value can be greatly improved and the porcelain strength can be improved. 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, when a is 0.
If it exceeds 0.8, the solid solution limit of Sr is exceeded, and Sr
This is because a crystal phase containing is precipitated and the Qf value decreases.
The replacement amount a of Ba with Sr is desirably 0.03 to 0.05 from the viewpoint of high Qf value and improvement of mechanical strength.

Further, zinc is added and contained in an amount of 4 to 18 parts by weight in terms of ZnO with respect to 100 parts by weight of the main component, because the zinc has a temperature coefficient of resonance frequency τf of less than 4 parts by weight. Is more than +15 [ppm / ° C.], and if it is more than 18 parts by weight, the temperature coefficient τf of the resonance frequency becomes smaller than −15 [ppm / ° C.], which is not practical. The zinc content is
From the viewpoint of making the temperature coefficient τf of the resonance frequency closer to 0, it is desirable to add 8.7 to 13.9 parts by weight to 100 parts by weight of the main component.

The reason that Ta is added and contained in an amount of 3 to 5 parts by weight in terms of Ta ₂ O ₅ with respect to 100 parts by weight of the main component is that Ta is less than 3 parts by weight in terms of Ta ₂ O _5. If the amount is more than 5 parts by weight, 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 bend of the temperature coefficient τf close to 0, it is desirable to add 3.5 to 4.5 parts by weight of Ta to 100 parts by weight of the main component in terms of Ta ₂ O ₅ .

Furthermore, in the present invention the (Ba _1-a Sr a) the ratio of TiO ₂ 1: was a 4, the ratio of TiO ₂ and _{(Ba 1-a Sr a)} 1: 3.9~ A ratio of about 1: 4.1 has excellent characteristics and is included in the present invention.

In the dielectric ceramic composition of the present invention, in the above composition formula, 0.03 ≦ a ≦ 0.05, and the main component 10
With respect to 0 parts by weight, zinc is converted to 8.7 to 13.
9 parts by weight, Ta and Ta ₂ O ₅ converted at 3.5 to 4.5 parts by weight additive be incorporated is desired. In this case, Qf
The value is 42000 [GHz] or more, the temperature coefficient τf of the resonance frequency is in the range of −4 to +6 [ppm / ° C.], and the bending (temperature drift) of the temperature coefficient τf of the resonance frequency is -1.1 to +
0.5 [ppm / ° C.]
The bending of the temperature coefficient τf of the resonance frequency, that is, the Qf value at which Δτf representing the temperature drift characteristic is close to zero can be 44000 or more.

The dielectric porcelain composition of the present invention contains B
The aTi ₄ O ₉ crystal phase exists as the main crystal phase, and the Ba ₃ Ti ₁₂ Zn ₇ O ₃₄ crystal phase, the Ba ₂ Ti ₉ O ₂₀ crystal phase, and the Ba ₂ Ti ₉ O ₂₀ crystal phase are uniformly dispersed in the porcelain. Things. Other crystals may be slightly precipitated. When the BaTi ₄ O ₉ crystal phase, the Ba ₃ Ti ₁₂ Zn ₇ O ₃₄ crystal phase, and the Ba ₂ Ti ₉ O ₂₀ crystal phase were analyzed by an X-ray microanalyzer (EPMA), it was found that Sr was in solid solution. It was confirmed. This Sr is composed of BaTi ₄ O ₉ , B
a ₃ Ti ₁₂ Zn ₇ O ₃₄ and a part of Ba in the crystal phase of Ba ₂ Ti ₉ O ₂₀ . In the present invention, Ba ₃ Ti
By precipitating the ₁₂ Zn ₇ O ₃₄ crystal phase, the Qf value can be improved and the temperature coefficient τf can be controlled from the plus side to the minus side. In addition, Ba ₂ Ti ₉ O ₂₀
The precipitation of the crystal phase makes it possible to make the temperature coefficient τf of the resonance frequency bend, that is, Δτf representing the temperature drift characteristic, to zero.

The dielectric porcelain composition of the present invention comprises BaCO ₃ , TiO ₂ , SrCO ₃ , ZnO, T
a ₂ O ₅ powders were prepared, weighed so as to have the above-mentioned composition ratio, pulverized and mixed with ZrO ₂ balls, calcined the mixed powders, and pulverized and mixed again with ZrO ₂ balls, The calcined powder is formed into a predetermined shape by a known method such as press molding or a doctor blade method, and is heated at 1200 to 1300 ° C. for 2 to 1 in the air or oxygen atmosphere.
It is obtained by firing for 0 hours. As the raw material powder, a metal salt such as a hydroxide, a carbonate, or a nitrate that generates an oxide by firing may be used. In the dielectric porcelain of the present invention, Al, Si, Ca, Mg, Fe, H
f, Sn, etc. may be included.

In the dielectric porcelain composition of the present invention, BaTi
_The Ba ₃ Ti ₁₂ Zn ₇ O ₃₄ crystal phase and the Ba ₂ Ti ₉ O ₂₀ crystal phase are uniformly dispersed in the ₄ O ₉ crystal phase to obtain BaTi ₄
O ₉ crystal phase, Ba ₃ Ti ₁₂ Zn ₇ O ₃₄ crystal phase and Ba
_In order to form a solid solution of Sr in the ₂ Ti ₉ O ₂₀ crystal phase, it is necessary to calcine at a temperature of 1050 to 1150 ° C. for 6 hours or more. The reason is that at temperatures lower than 1050 ° C, 6
This is because if the calcination is performed for less than an hour, a Ba ₃ Ti ₁₂ Zn ₇ O ₃₄ crystal phase is not easily formed.

[0022]

EXAMPLE As a raw material, BaCO ₃ , T having a purity of 99% or more was used.
Using powders of iO ₂ , SrCO ₃ , ZnO and Ta ₂ O ₅ , the a, Zn and Ta contents of the above composition formula were weighed so as to have the ratios shown in Table 1, and pure water was used as a medium, and ZrO was used.
_The mixture was wet-mixed for 20 hours in a ball mill using _two balls. The mixture is then dried (dehydrated) and dried at 1100 ° C. for 6 hours.
It was calcined for hours. This calcined product was pulverized 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.
/ Cm ^{2 at} a pressure of ² cm / cm ² , and baked at 1250 ° C. for 2 hours in an oxidizing atmosphere to give a diameter of 8 mm and a height of
mm cylindrical sample was obtained.

For the evaluation of the dielectric properties, the relative permittivity and the Q value at a frequency of 6 GHz were measured by the dielectric cylinder resonator method using the sample. Table 1 shows the value represented by the product of the Q value and the measurement frequency f. 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. Table 1 shows the results. Note that τf ₁ in Table 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. Further, the bending Δτf (temperature draft) of the temperature coefficient of the resonance frequency was obtained from the equation Δτf = τf ₁ −τf ₂ , and the results are shown in Table 1.

[0024]

[Table 1]

From Table 1, it can be seen that the dielectric ceramic composition of the present invention has a relative dielectric constant of 33 or more and a Qf value of 40000 [GH
z], the temperature coefficient τf of the resonance frequency is ± 15 [ppm
/ ° C], and the bending Δτf of the temperature coefficient τf of the resonance frequency has excellent characteristics of -2 to +2 [ppm / ° C]. It can also be seen that the Qf value where the bending Δτf of the temperature coefficient of the resonance frequency is near zero can be made a high Qf value of 43,000 or more.

[0026]

As described in detail above, according to the present invention, B
In the a-Ti dielectric ceramic composition, a part of Ba is replaced with S.
By substituting with r and adding a predetermined amount of Zn and Ta, the relative dielectric constant is 30 to 40 and Qf is 4
0000 [GHz] or more, the temperature coefficient τf of the resonance frequency is within the range of −15 to +15 [ppm / ° C.], and the bending of the temperature coefficient τf of the resonance frequency is −2 to +2.
[Ppm / ° C.], and the Qf value at which the bending Δτf of the temperature coefficient of the resonance frequency is close to zero is 4
0000 or more, and the porcelain strength can be further improved, so that various resonator materials, MIC dielectric substrate materials, and dielectric waveguide materials used in the frequency range of microwaves, millimeter waves, etc. And so on.

Continuation of front page (56) References JP-A-5-178660 (JP, A) JP-A-5-70222 (JP, A) JP-A-5-17213 (JP, A) JP-A-4-338168 (JP) JP-A-9-87015 (JP, A) JP-A-57-69607 (JP, A) JP-A-5-325641 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) C04B 35/46 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] (1) at least Ba, Ti, S as a metal element;
contains r, a main component 100 a composition formula of these molar ratios, when expressed as _{(Ba 1-a Sr a)} O-4TiO 2, wherein a is, to satisfy the 0.01 ≦ a ≦ 0.08 Parts by weight of Zn
4 to 18 parts by weight in terms of Ta, 3 to _{5 in} terms of Ta ₂ O ₅
A dielectric porcelain composition characterized by being added by weight.