JP2796905B2 - Method for producing transparent microwave dielectric - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is used in a wide range of fields, from radio equipment for mobile communication, to communication equipment using microwaves such as satellite broadcasting and satellite communication, or from decoration to various industries. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent microwave dielectric which can be easily and stably manufactured in industrial production.

[0002]

2. Description of the Related Art Dielectric ceramic compositions for various electronic devices that make use of the fact that the properties of ceramic compositions are low loss and have good temperature characteristics are low loss in the SHF band, including capacitors for temperature compensation. There are various dielectric porcelain compositions used for dielectric resonators for direct reception of satellite broadcasts, down converters, etc., microwave strip line substrates and the like.

In general, composite perovskite compounds have been widely used as dielectric ceramic compositions used for SHF bands. Conventionally, there is no dielectric material having an εr (relative dielectric constant) of 5 or more and a transparent dielectric (including an organic substance) having a low loss enough to be used in a microwave band. Used a transparent acrylic plate.

[0004]

The dielectric properties of the transparent acrylic plate are as follows: εr is about 2.5, and Q is 3000 to 5000.
(At 1 GHz) and the rate of change (τf) of the dielectric constant with temperature is as large as several hundred ppm / ° C., and considering the future increase in communication frequency, it is impossible to use a transparent acrylic plate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transparent microwave dielectric having a low εr of 5 or more and a low loss in a microwave band and a small change in characteristics with respect to a temperature change, and stably produce a highly transparent dielectric. It is an object of the present invention to provide a method for manufacturing a transparent microwave dielectric that can be used.

[0006]

According to the present invention, (Ba _{x
Sr y) (Ga 1/2 · Ta} 1/2) O 3 ( but x = 0.2~
0.3, y = 0.7-0.8) hot isostatic pressing in a single or mixed atmosphere of oxygen gas or Ar gas, or in an oxygen gas atmosphere And hot-pressing or sintering in an oxygen gas atmosphere.

More specifically, the present invention relates to (Ba _x · S
_{r y) (Ga 1/2 · Ta} 1/2) O 3 ( but x = 0.2~
(0.3, y = 0.7-0.8) The compact formed from the raw material powder in the composition range of primary sintering is subjected to primary sintering to obtain a theoretical density of 93
% Or more, in an atmosphere of oxygen gas or Ar gas alone or in a mixed atmosphere, at a temperature of 1350 to 1600 ° C., a pressure of 500 kg / cm ^{2 to} 2000 kg / cm ² , 0.5 to
Hot isostatic pressing for 20 hours (HIP)
Thus, the theoretical density of the sintered body is 99% or more.

[0008] In addition, the present invention _{is, (Ba x · Sr y)} (G
a _1/2 · Ta _1/2 ) O ₃ (where x = 0.2 to 0.3, y
= 0.7 to 0.8) in an oxygen gas atmosphere at a temperature of 1350 to 1600 ° C.
Pressure ^{500kg / cm 2 ~5000kg / cm 2} , 2~
After hot pressing for 20 hours (hereinafter referred to as HP)
The theoretical density of the sintered body is 99% or more.

[0009] In addition, the present invention is, (Ba _x · Sr _y)
(Ga _1/2 · Ta _1/2 ) O ₃ (where x = 0.2-0.
(3, y = 0.7-0.8) The molded body made of the raw material powder in the composition range of 1450-170 was prepared in an oxygen gas atmosphere.
It is characterized by sintering at 0 ° C. for 10 to 100 hours so that the theoretical density of the sintered body is 99% or more.

[0010]

[Action] The present invention, in order to obtain a transparent microwave dielectric, a result of various studies on the composition and manufacturing conditions, identify _{BaO-SrO-Ga 2 O 3} -Ta 2 O -based ceramic composition having a specific composition By sintering under the manufacturing conditions of
The present invention has been completed by finding that a transparent dielectric material having a small loss of 10 ppm / ° C. or less in a microwave band with low loss and a temperature change of 10 ppm / ° C. or less when r is 5 or more can be obtained.

The dielectric according to the present invention is transparent, translucent, and has low loss, so that it can be used in a high frequency band equal to or higher than the X band, and has a small characteristic change with temperature change. Has 5 or more properties,
The thickness of the dielectric can be reduced, and the size of a product incorporating the dielectric can be reduced.

Reasons for Limiting Composition In the present invention, the composition of the raw material powder of the dielectric is set to (Ba _{x
Sr y) (Ga 1/2 · Ta} 1/2) O 3 ( but x = 0.2~
0.3, y = 0.7-0.8)
When x of less than 0.2 or more than 0.3, a transparent porcelain cannot be obtained, and when y of Sr is less than 0.7 or more than 0.8, a transparent porcelain cannot be obtained. The molar ratio of 、,
The reason that the molar ratio of Ta is 1/2 is that A (1 / 2B ' ³⁺
[1 / 2B " ⁵⁺ ) O ₃ type perovskite compound composition deviates from the Q value, and the temperature coefficient of the resonance frequency increases, which is not preferable.

Manufacturing Conditions In order to obtain the dielectric according to the present invention, for example, after mixing and mixing the raw material powders in the above-described specific composition range, 1100
The calcined product is calcined at ℃ 1300 ° C. for 2 to 10 hours, pulverized and granulated, then formed into a required shape and debindered, and the formed product is subjected to HIP treatment, HP treatment or sintering.
In the case of primary sintering prior to HIP processing,
The sintering conditions are as follows: air, temperature 1400-1700
After primary sintering at 1 ° C. for 1 to 100 hours to make the theoretical density of the sintered body 93% or more, the temperature is set to 1350 to 16 in an atmosphere of oxygen gas or Ar gas alone or in a mixed atmosphere.
00 ° C, pressure 500kg / cm ² -2000kg / c
The sintered body is densified to a theoretical density of 99% or more by hot isostatic pressing (HIP) for 0.5 to 20 hours at m ² .

In the present invention, in the primary sintering before the HIP treatment, if the sintering temperature is lower than 1400 ° C., a compact having a relative theoretical density of 93% or more cannot be obtained. If the sintering time is less than 1 hour, a molded article having a relative theoretical density of 93% or more cannot be obtained. If the sintering time exceeds 100 hours, the effect of densification is saturated and the production cost is not preferred.

In the HIP process, in order to obtain a transparent dielectric, it is necessary to use oxygen gas or Ar gas alone or in a mixed atmosphere. Further, in the HIP treatment, if the heating temperature is lower than 1350 ° C., a molded article having a relative theoretical density of 99% or more cannot be obtained. If the heating temperature exceeds 1600 ° C., the effect of densification is saturated, the equipment becomes large, and the production cost is preferable. When the pressing force is less than 500 kg / cm ² , a molded article having a relative theoretical density of 99% or more cannot be obtained.
If it exceeds kg / cm ² , the effect of densification will be saturated, the equipment will become large and the production cost will be unfavorable, and if the treatment time is less than 0.5 hour, a molded article having a relative theoretical density of 99% or more will not be obtained. If the time exceeds 20 hours, the effect of densification is saturated, which is not preferable in terms of production cost.

In the present invention, when the molded body is subjected to the HP treatment, the temperature is 1350 to 1600 ° C. in an oxygen gas atmosphere.
Pressure ^{500kg / cm 2 ~5000kg / cm 2} , 2~
The treatment is performed under the condition of 20 hours, but the oxygen gas concentration is 50%.
The above is necessary, preferably 80 to 100%,
If the heating temperature is lower than 1350 ° C., a molded article having a relative theoretical density of 99% or more cannot be obtained. If the heating temperature exceeds 1600 ° C., the effect of densification is saturated, the equipment becomes large, and the production cost is not preferable. 9 for less than 500 kg / cm ²
A molded article having a relative theoretical density of 9% or more was not obtained.
If it exceeds 000 kg / cm ² , the effect of densification is saturated,
If the equipment is large, the production cost is not preferable. If the treatment time is less than 2 hours, a molded article having a relative theoretical density of 99% or more cannot be obtained. If the treatment time exceeds 20 hours, the effect of densification is saturated and the production cost is reduced. Not preferred.

In the present invention, when sintering a compact, the temperature is 1450-1700 ° C. in an oxygen gas atmosphere.
The treatment is performed under the conditions of 0 to 100 hours, and the oxygen gas concentration needs to be 50% or more, preferably 80 to 100%, and the molding having a relative theoretical density of 99% or more when the heating temperature is less than 1450 ° C. When the temperature exceeds 1700 ° C., the effect of densification is saturated, the equipment becomes large, which is not preferable in terms of manufacturing cost.
%, A molded article having a relative theoretical density of 10% or more cannot be obtained.
If the time exceeds 0 hours, the effect of densification is saturated, which is not preferable in terms of manufacturing cost.

[0018]

【Example】

Example 1 raw material powder _{(Ba x · Sr y) (} Ga 1/2 · Ta 1/2) O 3
However, after blending and mixing into a composition of x = 0.3 and y = 0.7,
After calcining at 1200 ° C. for 2 hours in the air, pulverized and granulated. Thereafter, the granulated powder is molded into an outer diameter of 12 mm × height of 20 mm, debindered, and further 155 in air.
Primary sintering was performed at 0 ° C. for 2 hours to make the relative theoretical density of the sintered body 94%.

The sintered body was subjected to HIP treatment under the conditions shown in Table 1, and the dielectric properties and the transparency (shown by the transmittance at a wavelength of 1 to 4 μm) of the obtained transparent porcelain were measured. Show.

[0020]

[Table 1]

[0021]

[Table 2]

[0022] Example 2 material powder _{(Ba x · Sr y) (} Ga 1/2 · Ta 1/2) O 3
However, after blending and mixing into a composition of x = 0.3 and y = 0.7,
After calcining at 1200 ° C. for 2 hours in the air, pulverized and granulated. Thereafter, the granulated powder was molded into an outer diameter of 12 mm × height of 20 mm, debindered, and the molded body was subjected to HP treatment under the conditions shown in Table 3, and the dielectric properties and transparency of the obtained transparent porcelain were measured. Table 4 shows the measured values.

[0023]

[Table 3]

[0024]

[Table 4]

[0025] EXAMPLE 3 raw material powder _{(Ba x · Sr y) (} Ga 1/2 · Ta 1/2) O 3
However, after blending and mixing into a composition of x = 0.3 and y = 0.7,
After calcining at 1200 ° C. for 2 hours in the air, pulverized and granulated. Thereafter, the granulated powder was molded into an outer diameter of 12 mm × height of 20 mm, debindered, and the compact was sintered under the conditions shown in Table 5, and the dielectric properties and transparency of the obtained transparent porcelain were measured. Table 6 shows the measured values.

[0026]

[Table 5]

[0027]

[Table 6]

[0028]

[Effect of the Invention] The present _{invention, (Ba x · Sr y)} (Ga
_1/2・ Ta _1/2 ) O ₃ (where x = 0.2-0.3, y =
A molded article having a composition of 0.7 to 0.8) is subjected to HIP treatment in an atmosphere of oxygen gas or Ar gas alone or in a mixed atmosphere, HP treatment in an oxygen gas atmosphere, or sintering in an oxygen gas atmosphere. Has a high density of at least 99% of theoretical density and high transparency, εr is 5 or more, Q is as large as 9000 or more (at 9 GHz), and the rate of change of dielectric constant (τf) with temperature is several ppm / ° C. Therefore, it is possible to stably obtain a transparent microwave dielectric material which is optimal for a higher communication frequency in the future.

Claims (1)

(57) [Claims] [Claim 1] _{(Ba x · Sr y) (} Ga 1/2 · Ta 1/2)
O ₃ (however, x = 0.2 to 0.3, y = 0.7 to 0.
The molded body made of the raw material powder in the composition region of 8) is subjected to hot isostatic pressing in an atmosphere of oxygen gas or Ar gas alone or in a mixed atmosphere, hot pressing in an oxygen gas atmosphere, or firing in an oxygen gas atmosphere. A method for producing a dielectric material for transparent microwaves, comprising: