JPH0746012A - Manufacture of dielectric resonator core - Google Patents

Abstract

PURPOSE:To provide a dielectric resonator core whose dimension precision and reliability is high, dielectric constant epsilonr is large, and Qu is excellent, and the variation of an electric characteristic is reduced. CONSTITUTION:At the time of manufacturing a dielectric resonator core 1 by injection molding a compound constituted of a dielectric ceramic powder and binder, and then degreasing and firing the obtained injection-molded body, the resin materials and mixing ratio of the binder, and the materials, composition range and median diameter, temperature rise rate at the time of degreasing, and firing temperature of the dielectric ceramic powder are controlled. For example, ethylene-vinylacatate copolymer and poly methacylate isobutyl are used as the binder, and the weight ratio (poly methacylate isobutyl/ethylene- vinylacatate copolymer) is made more than 1. Thus, sink marks generated at the prepared dielectric resonator core 1 can be suppressed, and the generation of cracks or the like can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a dielectric resonator core, and more particularly to a method for manufacturing a dielectric resonator core by injection molding.

[0002]

2. Description of the Related Art In recent years, mobile communication devices such as car phones and mobile phones are rapidly becoming popular. A dielectric filter is used as an antenna duplexer in the mobile communication device,
This dielectric filter is configured by combining a plurality of coaxial dielectric resonators.

The coaxial dielectric resonator described above has a dielectric resonator core covered with a metal conductor film. The dielectric resonator core is made of a dielectric ceramic and has a hole 2 in the center thereof to form a substantially rectangular parallelepiped as shown in the perspective view of FIG. 1 and the sectional view of FIG. A groove 3 may be provided on the upper surface 1 a of the dielectric resonator core 1 so as to surround the hole 2.

In order to manufacture the dielectric resonator core 1, dielectric ceramic powder is mixed with a binder and press-formed into granules, or a compound in which the dielectric ceramic powder and the binder are kneaded is used. It suffices to perform injection molding, degrease and fire the molded body.

[0005]

When the dielectric resonator core 1 is manufactured, it is required that there be no sink mark, crack, break after degreasing and firing, and the manufactured dielectric resonator core 1 is manufactured. Has high dimensional accuracy,
High relative permittivity εr and low dielectric loss, that is, Q
It is required that the deterioration of u is small.

However, in practice, during degreasing, there are problems such as formation of dents and bulges on the outside of the molded body, sink marks and cracks in the holes 2, and cracks and cracks inside the molded body. Often occurs. Further, the manufactured dielectric resonator core 1 often varies in relative permittivity εr.

Therefore, the present invention has been proposed in view of such conventional circumstances, and by appropriately controlling the manufacturing conditions of the dielectric resonator core, the dielectric resonator having excellent characteristics and high reliability is provided. It is an object to provide a method for manufacturing a body resonator core.

[0008]

The present invention has been proposed to achieve the above object. That is, the present invention relates to a method for producing a dielectric resonator core in which a compound consisting of a dielectric ceramic powder and a binder is injection-molded, and the resulting injection-molded body is degreased and fired. A vinyl copolymer and polyisobutyl methacrylate were used, and the ratio (polyisobutyl methacrylate / ethylene vinyl acetate copolymer) was 1 by weight.
That is all.

The above ethylene vinyl acetate copolymer (EV
The ratio (A) to polyisobutyl methacrylate (PIBMA) (polyisobutyl methacrylate / ethylene vinyl acetate copolymer) (hereinafter referred to as PIBMA / EVA) is 1.
If it is less than 50 μm, the injection-molded body will have 50 μm in the degreasing process.
A sink mark of m or more occurs, and the dimensional accuracy deteriorates. The ratio of the above binders (PIBMA / EVA) is 5/4.
By the above, the sink mark can be further reduced.

The dielectric ceramic powder used here is xBaO.wBiO.y {(1-m) Nd ₂ O.
₃ · mSm ₂ O ₃ } · zTiO ₂
Moreover, the composition range is 12.0 ≦ x ≦ 16.0 14.0 ≦ y ≦ 18.0 66.5 ≦ z ≦ 70.5 0.5 ≦ w ≦ 16.0 x + y + z + w = 100 mol% 0.1 It is preferable that ≦ m ≦ 0.5.

More preferably, it is represented by a composition formula similar to the above composition formula, and its composition range is 13.0 <x <14.5 14.5 <y <16.5 68.0 <z <70. 0 0.5 ≦ w ≦ 1.5 x + y + z + w = 100 mol% 0.4 ≦ m ≦ 0.5.

By using the dielectric ceramic powder having the composition formula and composition range as described above, the unloaded Q
A dielectric resonator core having excellent dielectric characteristics such as u, relative permittivity εr, and frequency temperature coefficient τf can be produced.

The degreasing was carried out by raising the temperature from room temperature to 600 ° C., and at this time, the temperature rising rate was 80-
Up to 200 ° C, 3.3 ° C / hour or less, 200 to 350 ° C
Up to 12 ° C / hour or less, up to 350-420 ° C up to 30
C./hour or less is preferable. If the temperature is rapidly increased from the above rate of temperature rise, sink marks of 50 μm or more will occur in the degreased molded body.

Further, it is preferable that the dielectric ceramic powder has a median diameter of 1.0 to 3.0 μm. If the median diameter is smaller than the above range, deep cracks are formed from the outside to the inside of the molded body due to the steps of degreasing and firing. Further, when the median diameter is larger than the above range, a large depression is generated on the outer side of the molded body due to the steps of degreasing and firing, and a large sink mark is generated by losing the linearity of the inner wall of the pores, and cracks or cracks occur Will occur.

Furthermore, the above firing is 1335 to 135
It is preferably carried out at 5 ° C. If the firing temperature deviates from the above range, Qu will be greatly deteriorated.

[0016]

When the present invention is applied to properly regulate the median diameter of the dielectric ceramic powder, the composition of the binder, the temperature rising rate at the time of degreasing, and the firing temperature, sink marks generated in the produced dielectric resonator core can be obtained. It can be kept small. Therefore, it is possible to manufacture a dielectric resonator core having high dimensional accuracy and high reliability without cracks, cracks, or cracks. Further, it is possible to manufacture a material having a large relative permittivity εr and a small dielectric loss, that is, a material having a large Qu.

[0017]

EXAMPLES Specific examples to which the present invention is applied will be described in detail below.

A dielectric resonator core 1 manufactured by applying the present invention is a substantially rectangular parallelepiped having a hole 2 in the center as shown in a perspective view of FIG. 1 and a sectional view of FIG. The upper surface 1a of the dielectric resonator core 1 has a structure in which a relatively shallow groove 3 is provided so as to surround the hole 2.

In this embodiment, the upper surface 1a of the dielectric resonator core 1 having the above-mentioned structure is about 3.5 mm.
It was formed so that the diameter of the hole 2 was about 1.5 mm.

In order to manufacture the above-described dielectric resonator core, first, materials having the following compositions were prepared. BaCO ₃ 13.9 mol% Bi ₂ O ₃ 1.5 mol% Nd ₂ O ₃ 12.7 mol% Sm ₂ O ₃ 3.2 mol% TiO ₂ 68.7 mol%

The above materials were weighed, wet-mixed with pure water in a ball mill, dried, and then pulverized by a raker. Further, after calcination in an oxygen atmosphere at 1200 ° C., it was pulverized by an Ishikawa type raiki machine for 15 minutes at a rotation speed of 20 times / minute to obtain a dielectric ceramic powder having a median diameter of 3.0 μm.

Further, a binder and an additive having the following composition were added to the above-mentioned dielectric ceramic powder, and the mixture was heated and kneaded to obtain a compound.

Composition of Binder and Additives Ethylene-vinyl acetate copolymer 45% by weight Polyisobutyl methacrylate 45% by weight Other additives 10% by weight

The content of the above components was 15% by weight with respect to the dielectric ceramic powder. If the amount is too small, the fluidity of the compound is insufficient, and molding defects are likely to occur during injection molding. On the other hand, if the amount is too large, cracks or deformations may occur in the degreasing and firing steps.

Next, using an injection molding machine, the compound obtained as described above was poured into a mold to obtain an injection molded body.

Then, the above injection molded body is put in a degreasing furnace,
Degreasing was performed by raising the temperature from room temperature to 600 ° C. in the atmosphere. The temperature rise from 80 to 420 ° C. was performed at the following rate (Pattern 1).

Temperature rising rate (Pattern 1) 80 to 200 ° C. 3 ° C./hour 200 to 350 ° C. 6 ° C./hour 350 to 420 ° C. 28 ° C./hour

Further, the degreased molded body is 1335.
The dielectric resonator core 1 was obtained by firing in air at 5 ° C. for 5 hours.

The following Experiments 1 to 4 were conducted on the dielectric resonator core 1 produced as described above in order to investigate various characteristics.

Experiment 1 First, the ratio of EVA and PIBMA (PIBMA / EV
The change in the characteristics of the dielectric resonator core produced by changing A) will be examined.

Therefore, Examples 1 to 3 were carried out according to the above-mentioned method except that the compositions A to D shown in Table 1 were used as the binder and the additive mixed with the dielectric ceramic powder.
3. A sample of the dielectric resonator core of Comparative Example 1 was prepared.

[0032]

[Table 1]

Then, sink marks were observed for each of the above-mentioned samples. The sink mark is a strain on the outer wall surface or the inner wall surface of the dielectric resonator core 1, and as shown in FIG. 3, the difference d ₁ between the outer wall surface 1b during injection molding and the outer wall surface 1c after firing. ,
Alternatively, it shows the difference d ₂ between the inner wall surface 2b during injection molding and the inner wall surface 2c after firing. Here, measurement was performed by slicing the center portion of each sample after firing along the holes 2 and observing with a tool microscope.

The results of measuring the size of sink marks as described above are shown in Table 2, and FIG. 4 shows the relationship between the ratio of EVA and PIBMA (PIBMA / EVA) and the size of sink marks.

[0035]

[Table 2]

From this, the ratio of EVA and PIBMA (P
It can be seen that the larger the value of (IBMA / EVA) is, the smaller the sink mark can be suppressed. Therefore, (PIBMA
The value of / EVA is 1 or more, and (PIBMA /
It was found that the sink mark was suppressed and the dimensional accuracy was improved by setting the value of EVA) to 5/4 or more.

Experiment 2 Next, changes in the characteristics of the dielectric resonator core produced as described above due to changes in the temperature rising rate during degreasing will be examined.

Therefore, in addition to the above-described temperature rising rate (Pattern 1), degreasing was performed by raising the temperature at the following patterns 2 and 3. At this time, as shown in FIG. 5, the molded bodies 4 to be degreased were arranged in the zirconium setter 5 and placed in the degreasing furnace.

Rate of temperature rise (Pattern 2) 80 to 200 ° C. 3.3 ° C./hour 200 to 350 ° C. 12 ° C./hour 350 to 420 ° C. 30 ° C./hour

Rate of temperature rise (Pattern 3) 80 to 200 ° C. 8 ° C./hour 200 to 350 ° C. 30 ° C./hour 350 to 420 ° C. 70 ° C./hour

The temperature rising rate is 80 to 420 ° C.
Although only shown, in reality, the temperature is from room temperature to 60
Degreasing is performed by raising the temperature to 0 ° C. Degreasing has not started at 80 ° C. or lower, and the binder and the like have already flowed out at 420 ° C. or higher. Therefore, it is not necessary to set the rate in particular, and it may be set only in consideration of workability.

Further, in order to clearly understand the process of increasing the temperature of each of the above patterns 1 to 3, FIG. 6 shows a graph of the temperature increasing rate of each pattern.

Then, dielectric resonator cores were prepared according to the method described above except that degreasing was performed at the above-mentioned temperature rising rate, and samples of Examples 4 and 5 and Comparative Example 2 were obtained. Then, the sink mark was measured for each sample, and the result is shown in Table 3.
Shown in.

[0044]

[Table 3]

From Table 3, the sink marks were suppressed to 50 μm or less in the samples degreased at the heating rates of Patterns 1 and 2, but at the heating rates of Pattern 3, the sink marks of the samples exceeded 100 μm. You can see that it is closed. Therefore, the temperature rising rate during degreasing is 80 to
Up to 200 ° C, 3.3 ° C / hour or less, 200 to 350 ° C
Up to 12 ° C / hour or less, up to 350-420 ° C up to 30
It was found that the shrinkage was suppressed and the dimensional accuracy was improved by performing the heating at a temperature of not higher than C / hour.

Experiment 3 Further, the median diameter of the dielectric ceramic powder used was changed, and the change in the characteristics of the produced dielectric resonator core was investigated.

When the dielectric ceramic powder is prepared, the temperature of the calcination is changed to obtain the dielectric ceramic powder having different median diameters. The calcination temperature is an effective temperature measured by thermoring, and the median diameter is measured by a laser diffraction particle size distribution measuring device. FIG. 7 shows the relationship between the calcination temperature and the median diameter.

From FIG. 7, the higher the calcination temperature, the larger the median diameter of the dielectric ceramic powder produced,
1.0-3.0μ when calcined at 1100-1230 ° C
It can be seen that the median diameter is m.

Dielectric ceramic powders having various median diameters were used to prepare dielectric resonator cores according to the method described above, and sink marks, cracks, and cracks were observed.

As a result, the dielectric resonator core formed by using the dielectric ceramic powder having a median diameter smaller than 1.0 μm had deep cracks extending from the outer wall surface to the inside. Further, in the case where the dielectric ceramic powder having a median diameter larger than 3.0 μm was used, the inner wall surface was largely depressed, sink marks of 100 μm or more were generated, and cracks and cracks were generated.

On the other hand, in the dielectric resonator core formed by using the dielectric ceramic powder having a median diameter of 1.0 to 3.0 μm, the sink mark is suppressed to 30 μm or less, and cracks and cracks are not seen at all. There wasn't.

Therefore, when the dielectric resonator core is formed by using the dielectric ceramic powder having a median diameter of 1.0 to 3.0 μm, sink marks are suppressed and cracks and cracks can be prevented. It was found that the dimensional accuracy of the product was improved and it became more reliable.

Experiment 4 Further , changes in the characteristics of the dielectric resonator cores produced by changing the firing temperature were examined.

Therefore, a dielectric resonator core was prepared according to the method described above, except that the dielectric resonator core was fired at various firing temperatures. As the binder and the additive mixed with the dielectric ceramic powder, those having the following compositions were used.

EVA 30% by weight PIBMA 60% by weight Stearic acid 10% by weight

Then, 1329 ° C., 1349 ° C., 136
The relative dielectric constants εr and Qu of the dielectric resonator cores prepared at three different firing temperatures of 1 ° C. were measured. Figure 8
In addition, this result is shown by a circle as the relationship between the firing temperature and εr and Qu. In addition, what is shown by a □ mark in FIG. 8 is data about a dielectric resonator core that is formed by press molding for comparison. Further, the firing temperature is shown as an effective temperature measured by thermoring.

It can be seen from FIG. 8 that εr slightly improves as the firing temperature increases. Further, it can be seen that although the Qu is sharply improved as the firing temperature is increased, it is rapidly reduced when the firing temperature exceeds 1350 ° C. It can be seen that in order to secure Qu of 280 or more, the firing temperature should be set in the range of 1335 to 1355 ° C.

Further, the above 1329 ° C., 1349 ° C., 13
Regarding the dielectric resonator cores (samples of Comparative Example 3, Example 6, and Comparative Example 4) prepared at three firing temperatures of 61 ° C., the values of εr and Qu, the dielectric resonator core The results of measuring the height L are shown in Table 4.

[0059]

[Table 4]

The data of εr, Qu, and L are measured from the number of samples indicated by n in Table 4, and the average value AVG, variation 3σ, and AVG / 3.
It is shown by σ, the maximum value MAX, and the minimum value MIN. Further, data for a dielectric resonator core (referred to as Comparative Example 5) formed by press molding for comparison is also shown.

From Table 4, comparing the sample of Comparative Example 5 with the other samples, it can be seen that the variation 3σ in height L is greatly reduced and the dimensional accuracy is improved by injection molding. Further, in Example 6, the same level of Qu as that of the sample of Comparative Example 5 obtained by press molding was obtained, and its variation was smaller than that of the sample of Comparative Example 5. Furthermore, it can be seen that the sample of Example 6 has a very small variation in εr.

In this way, the firing temperature is set between 1335 and 135.
When the temperature is set to 5 ° C., not only high Qu can be secured, but also variations in Qu and εr can be suppressed. That is, a dielectric resonator core having stable electric characteristics can be manufactured. Also, the dimensional accuracy is excellent.

[0063]

As apparent from the above description, when the present invention is applied and the median diameter of the dielectric ceramic powder, the composition of the binder, the temperature rising rate during degreasing, and the firing temperature are properly regulated, it is produced. It is possible to suppress the sink mark generated in the formed dielectric resonator core. Therefore, it is possible to manufacture a dielectric resonator core having high dimensional accuracy and high reliability without cracks, cracks, or cracks.

Further, the relative permittivity εr is large, and Qu
It is also possible to manufacture excellent products. further,
Since the variation in the electric characteristics is small, the dielectric resonator core has high reliability.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration example of a dielectric resonator core.

FIG. 2 is a cross-sectional view showing a configuration example of a dielectric resonator core.

FIG. 3 is a cross-sectional view for explaining sink marks generated in a dielectric resonator core.

FIG. 4 is a characteristic diagram showing the relationship between the weight ratio PIBMA / EVA and the size of the sink mark.

FIG. 5 is a perspective view schematically showing the arrangement of injection-molded products during degreasing.

FIG. 6 is a characteristic diagram showing a relationship between time and temperature for showing a temperature rising rate pattern during degreasing.

FIG. 7 is a characteristic diagram showing the relationship between calcination and median diameter.

FIG. 8 is a characteristic diagram showing a relationship between a firing temperature and εr or Qu.

[Explanation of symbols]

 1 ... Dielectric resonator core 2 ... Hole

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H01P 7/04 (72) Inventor Kazuharu Iwasaki 6-35 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation Within

Claims (6)

[Claims] 1. A method for producing a dielectric resonator core, comprising: injection-molding a compound consisting of a dielectric ceramic powder and a binder, and then degreasing and firing the obtained injection-molded body, wherein ethylene vinyl acetate is used as the binder. A method for producing a dielectric resonator core, characterized in that a copolymer and isobutyl methacrylate are used, and a ratio thereof (polyisobutyl methacrylate / ethylene vinyl acetate copolymer) is set to 1 or more by weight ratio. 2. The dielectric ceramic powder is xBaO.wB.
iO · y {(1-m) Nd ₂ O ₃ · mSm ₂ O ₃ } · z
TiO ₂ is represented by a composition formula and its composition range is 12.0 ≦ x ≦ 16.0 14.0 ≦ y ≦ 18.0 66.5 ≦ z ≦ 70.5 0.5 ≦ w ≦ 16. The method of manufacturing a dielectric resonator core according to claim 1, wherein 0 x + y + z + w = 100 mol% 0.1 ≦ m ≦ 0.5. 3. The weight ratio of ethylene vinyl acetate copolymer to polyisobutyl methacrylate (isobutyl methacrylate / ethylene vinyl acetate copolymer) is 5/4 or more. Manufacturing method of dielectric resonator core of. 4. The temperature rising rate for degreasing is 80 to 2
3.3 ° C / hour or less up to 00 ° C, 12 ° C / hour or less up to 200-350 ° C, 30 ° C up to 350-420 ° C
/ Hour or less, The method for manufacturing a dielectric resonator core according to claim 1, wherein 5. The method for manufacturing a dielectric resonator core according to claim 1, wherein the median diameter of the dielectric ceramic powder is 1.0 to 3.0 μm. 6. The method for manufacturing a dielectric resonator core according to claim 1, wherein the firing is performed at 1335 to 1355 ° C.