JPH05325638A - High-frequency dielectric porcelain - Google Patents

Abstract

PURPOSE:To obtain a high-frequency dielectric porcelain which has a high quality factor and high reliability in a high-temperature and high humidity atmosphere with the oxides of at least two components or more contained and arithmetical mean deviation of profile of the surface being 0.6mum to 4.9mum. CONSTITUTION:BaCO3, TiO2 of chemically high purity is used, which is mixed, for instance, to be a composition of Ba:20.0mol% and Ti:80mol%, and processed by wet mixing, dried and then preliminarily baked, and after that, the preliminarily baked powder is further ground, and after hydrated and dried, a proper amount of caking additive is added thereto and then molded by pressing. The molded body is baked to obtain a sintered body. The surface of the sintered body is ground with abrasive grains of 0.7mum to 5mum to obtain a dielectric porcelain having arithmetic mean deviation of profile of 0.6mum to 4.9mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric resonator for use in a high frequency region such as a microwave and a millimeter wave band, and a high frequency dielectric ceramic suitable for a dielectric filter and the like.

[0002]

2. Description of the Related Art Conventionally, dielectrics have been used for impedance matching of circuits, dielectric resonators, filters, etc. in the high frequency range, and the Q value is large in the high frequency range with the recent increase in the communication frequency. There is a demand for dielectric porcelain whose characteristics change little in the use environment.

As a conventional porcelain composition for dielectric elements,
XBaO.yMg described in JP-A-53-60544
O.zTa ₂ O ₅ system and the like have been proposed. This material has a high Q value and a small rate of change in temperature with resonance frequency.

[0004]

However, in the case of a dielectric porcelain which is used in a high frequency band such as a microwave band or a millimeter wave band and which is composed of an oxide of two or more components, the quality of the porcelain surface has a large Q value. Therefore, it is difficult to obtain a high Q value only by the above-mentioned conventional composition control, and there is a problem that the Q value deteriorates when used at high temperature and high humidity.

In order to solve the above-mentioned problems of the prior art, the present invention has a high Q value even in a high frequency region by controlling the surface roughness of porcelain and has high reliability in a high temperature and high humidity atmosphere. An object is to provide a dielectric ceramic.

[0006]

In order to achieve the above object, the high frequency dielectric ceramic of the present invention contains an oxide of at least two components, and the center line average roughness of the surface of the ceramic molding is 0. It is characterized by being 6 μm or more and 4.9 μm or less.

In the above structure, it is preferable that the high frequency dielectric ceramic has a metal oxide having a composite perovskite structure as a main component and a TE ₀₁ δ mode resonance frequency of 17.9 GHz or higher.

In the above structure, the high frequency dielectric porcelain is Ba [Zr _x (Mg _1-v Co _v ) _y Ta _z ] _w
O _n (n is an arbitrary number), x + y + z = 1 and 0 ≦ x0.025, 0.28 ≦ y ≦ 0.335, 0.
It is preferable that the main component is an oxide in the range of 665 ≦ z ≦ 0.689, 0 ≦ v ≦ 0.25 and in the range of 0.97 ≦ w ≦ 0.99.

[0009]

According to the structure of the present invention, a high Q value is obtained,
It is possible to obtain a high-frequency dielectric ceramic having high reliability in a high temperature and high humidity atmosphere.

Further, the high frequency dielectric porcelain contains a metal oxide having a composite perovskite structure as a main component and has a frequency of 17.9 GHz.
According to the preferable configuration having the above TE ₀₁ δ mode resonance frequency, the influence of the center line surface roughness on the Q value becomes large at a frequency of 17.9 GHz or higher, and the center line surface roughness is 0.6 μm or more. Although a very small Q value can be obtained in a small range, this can be improved.

Furthermore, the dielectric ceramics for high frequency use Ba [Zr
_{x (Mg 1-v Co v} ) is represented by _{y Ta z] w O n (} n
Is an arbitrary number), x + y + z = 1 and 0 ≦ x0.02
5, 0.28≤y≤0.335, 0.665≤z≤0.
689,0 ≦ v ≦ 0.25, and 0.9
According to the preferable constitution in which the oxide as the main component is in the range of 7 ≦ w ≦ 0.99, the high Q value is 20,000 or more even at the high frequency of 18.2 GHz and the characteristics after the high temperature and high humidity test are performed. Can also be stabilized.

[0012]

The present invention will be described in more detail with reference to the following examples. Example 1 As a starting material, chemically highly pure BaCO ₃ , TiO 2 was used.
₂ are used, and these are Ba: 20.0 mol%, Ti:
The composition was weighed so as to have a composition of 80 mol%, and wet-mixed using a ball mill.

After the mixture is dried and calcined at 800 ° C. for 2 hours, the calcined powder is further pulverized by a ball mill, dehydrated and dried, and an appropriate amount of polyvinyl alcohol is added as a binder to give 1 ton / cm ^2. Then, a disk having a diameter of 7 to 13 mm, a thickness of 2.8 mm and a thickness of 5.2 mm was formed. This compact was fired at 1300 ° C. for 12 hours to obtain a sintered body. The surface of this sintered body is 0.7 μm to 5 μm.
Grinding with abrasive grains of μm gave dielectric porcelains having different center line average roughness. The relative density of the sintered body was 97 for all samples.
% Or more. Characteristics are TE ₀₁ δ mode resonance frequency: F ₀ , no load Q: Q by conductor cavity type dielectric cylinder resonator method.
Was measured. The center line surface roughness of the sample is JIS B06.
51, and JIS B0601 according to a stylus type surface roughness measuring device. After measuring the surface roughness,
The sample was left in an atmosphere of 95% RH for 100 hours to conduct a high temperature and high humidity test. After the test, the sample was left in an atmosphere of 25 ° C. and 50% RH for 1 hour, and the unloaded Q: Q ′ after the test was measured. Table 1 shows the resonance frequency of the sample: F ₀ (GHz), center line average roughness:
R (μm), unloaded Q: Q, and change rate of unloaded Q ′ after high temperature and high humidity test: Q / (Q−Q ′) (%) are shown.

[0014]

[Table 1]

As is clear from Table 1, when the Q values of the samples in the same frequency band are compared, the center line surface roughness is R <0.6.
It was confirmed that the Q value was remarkably small in the range of 1 and the deterioration of the Q value by the high temperature and high humidity test was large in the range of R> 4.9. This is the same in any frequency band. The dielectric ceramic according to the present invention has a high Q value, and the characteristics after the high temperature and high humidity test are stable.

Example 2 As a starting material, chemically highly pure BaCO ₃ , Zn
O, Nb ₂ O ₅ and Ta ₂ O ₅ are used and these are Ba:
50.0 mol%, Zn: 16.7 mol%, Nb1
The composition was weighed so as to have a composition of 3.3 mol% :, Ta: 20.0 mol%, and wet-mixed using a ball mill.

After the mixture is dried and calcined at 900 ° C. for 2 hours, the calcined powder is further crushed by a ball mill, dehydrated and dried, and an appropriate amount of polyvinyl alcohol is added as a binder to give 1 ton / cm ^2. Is applied to form a disk having a diameter of 2.5 to 7 mm and a thickness of 1 to 2.8 mm. This compact was fired at 1500 ° C. for 24 hours to obtain a sintered body.

From the X-ray diffraction, it was confirmed by the X-ray diffraction that the perovskite phase was the main phase and a slight amount of unknown phase was present in the produced phase on the surface of the sintered body. In addition, the relative density of the sintered body was 9 for all samples.
It was 8% or more.

The surface of this sintered body was ground with abrasive grains of 0.7 μm to 5 μm to obtain dielectric ceramics having different center line average roughness. The characteristics, the measurement of the center line average surface roughness, and the high temperature and high humidity test were performed in the same manner as in Example 1. In Table 2, the resonance frequency of the sample: F ₀ (GHz), the center line average roughness: R (μm),
The no-load Q: Q and the change rate of the no-load Q'after the high temperature and high humidity test: Q / (Q-Q ') (%) are shown.

[0020]

[Table 2]

As is clear from Table 2, the Q value is small in the range where the center line surface roughness is smaller than 0.6 μm. Especially at a frequency of 17.9 GHz or more, the influence of the center line surface roughness on the Q value becomes large, and the center line surface roughness becomes 0.6.
It was confirmed that only a very small Q value was obtained in the range smaller than μm.

When the center line surface roughness is larger than 4.9 μm, the Q value is greatly deteriorated by the high temperature and high humidity test, and particularly at a frequency of 17.9 GHz or higher, the Q value is remarkably deteriorated. Dielectric porcelain having a composite perovskite structure as a main component has a high F ₀ Q product and is expected to be used in a high frequency region. However, especially in a high frequency region, the surface properties greatly influence the characteristics, and the Q value depends on it. It has a great impact. In the range according to the present invention, it has a high Q value and the characteristics after the high temperature and high humidity test are stable.

Example 3 As a starting material, chemically highly pure BaCO ₃ , ZrO
₂ , MgO, CoO, and Ta ₂ O ₅ were used. Then Table 3
4 to 4 are weighed, pulverized with a ball mill, dehydrated and dried, and added with polyvinyl alcohol as a binder in an appropriate amount and a pressure of 1 ton / cm ² to give a diameter of 4 mm and a thickness of 1 It was molded into a disc of 0.6 mm. This compact was fired at 1600 ° C. for 20 hours to obtain a sintered body.

As in Example 2, the generation phase on the surface of the sintered body was confirmed by X-ray diffraction to have a trace amount of unknown phase with the perovskite phase as the main phase. The relative density of the sintered bodies was 98% or more in all the samples.

The surface of this sintered body was polished with abrasive grains of 0.7 μm to 5 μm to obtain dielectric ceramics having different center line average roughness. The characteristics, the measurement of the center line average surface roughness, and the high temperature and high humidity test were performed in the same manner as in Example 1. The resonance frequency of each sample is in the range of 18.20 ± 0.02 GHz. Tables 3 and 4 show sample compositions: x, y, z, w, v,
Centerline average roughness: R (μm), unloaded Q: Q, and rate of change of unloaded Q ′ after high temperature and high humidity test: Q / (Q−Q ′)
(%) Is shown.

[0026]

[Table 3]

[0027]

[Table 4]

As is clear from Tables 3 and 4, Q is remarkably small in the range where the center line surface roughness is smaller than 0.6 μm,
It was confirmed that the deterioration of the Q value due to the high temperature and high humidity test was extremely large in the range larger than 4.9 μm. Further, outside the composition range of the present invention, Q is small or does not sinter regardless of the centerline surface roughness. 18.2 GHz in the range according to the invention
Even at such a high frequency, it had a high Q value of 20,000 or more, and the characteristics after the high temperature and high humidity test were stable.

When the center line surface roughness falls within the scope of the claims of the present invention, the composition of the dielectric ceramic is Ba [Z].
_{r x (Mg 1-v Co} v) y Ta z] that with _w O _n is particularly exhibits a large effect, the similar phenomenon in compositions with other high Q value occurs is apparent.

[0030]

As described above, according to the present invention, a high Q value is obtained by containing an oxide of at least two components and having a surface center line average roughness of 0.6 μm or more and 4.9 μm or less. Thus, it is possible to obtain a high-frequency dielectric ceramic having high reliability in a high temperature and high humidity atmosphere.

Claims (3)

[Claims] 1. An oxide containing at least two components,
A high frequency dielectric porcelain, characterized in that the center line average roughness of the surface of the porcelain compact is 0.6 μm or more and 4.9 μm or less. 2. The high frequency dielectric ceramic according to claim 1, wherein the high frequency dielectric ceramic is mainly composed of a metal oxide having a composite perovskite structure and has a TE ₀₁ δ mode resonance frequency of 17.9 GHz or higher. 3. A high frequency dielectric ceramic is made of Ba [Zr
_{x (Mg 1-v Co v} ) is represented by _{y Ta z] w O n (} n
Is an arbitrary number), x + y + z = 1 and 0 ≦ x0.02
5, 0.28≤y≤0.335, 0.665≤z≤0.
689,0 ≦ v ≦ 0.25, and 0.9
The high frequency dielectric ceramic according to claim 1, wherein an oxide in the range of 7 ≦ w ≦ 0.99 is a main component.