JPS62252008A - Manufacturing method of dielectric material for microwave - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for manufacturing a ceramic composition used for dielectric resonators, etc. in the microwave band, and more specifically,
The present invention relates to a method of manufacturing a (CoZnNb)Os-based dielectric ceramic.

[Prior Art] It is well known that dielectric ceramics are often used as filters and the like in the field of communication using microwaves such as automobile radio and satellite communications δ. With recent remarkable advances in microwave semiconductor devices and integrated circuits,
There is an increasing demand for miniaturization of circuit elements such as dielectric filters and recirculators used in such fields.

The shape of these elements using dielectric ceramics is determined primarily by the dielectric constant of the ceramic, so materials are required that have a high dielectric constant, low loss, and excellent temperature stability.

Dielectric ceramic compositions for microwave use that meet these requirements include Ba (CoNb)Os and Ba (ZnT).
a) Materials such as Os-based materials have been developed.

[Problems to be solved by the invention] Among them, Ba (CoZnNb)Ox-based dielectric ceramics are excellent materials that can satisfy the above requirements, but their properties, especially the Q value, vary greatly depending on manufacturing conditions. The problem was that there was wide variation.

Also, in terms of manufacturing conditions, it is relatively high temperature (14Q O
Porcelain with good microwave properties cannot be obtained unless it is fired for a long time (usually about 20 hours), leading to problems such as poor productivity and high manufacturing costs.

The purpose of the present invention is to eliminate the drawbacks of the prior art as described above,
A method of manufacturing a Ba(CoZnNb)Oy-based microwave dielectric material with a high dielectric constant (good temperature characteristics and small Irrigation temperature) in a short firing time and with less variation in characteristics. It is about providing.

[Means for solving the problems] The present invention, which can achieve the above objects, has the following features:
I X) B a (C01/3N bzzi)
03+ X B a (Z n+z, lN bzzi
> 03 (however, 0<x<0.75) is fired in the atmosphere, and the resulting porcelain composition is
This is a method for producing a dielectric material for microwave use, which is heat-treated in an inert gas atmosphere at 250 to 1400°C.

Ba(CoZnNb)03-based dielectric ceramics are fired in the atmosphere. This is because firing in a nitrogen gas atmosphere lowers the Q value and makes it unusable.The present inventor has repeatedly conducted trial production experiments with various firing conditions for Ba(CoZnNb) based dielectric ceramic compositions. , After firing in the air, heat treatment (annealing) in an inert gas atmosphere at a temperature slightly lower than the firing temperature.
By doing this, the dielectric constant can be reduced without decreasing Q
(I learned that only i can be significantly improved, and completed the present invention.)

In the present invention, firing is carried out at 1400°C in the air as in the past.
However, the firing time may be much shorter than in the prior art, less than 10 hours, usually about 2 to 3 hours. Heat treatment is 1250-140, which is slightly lower than the firing temperature.
The process is carried out at 0°C in an inert gas atmosphere. As the inert gas, for example, nitrogen gas can be used;
level or higher.

The heat treatment temperature was set at 1250 to 1400°C.
If it is below 0℃, the effect of heat treatment will hardly occur, and on the contrary, I40
This is because if the temperature exceeds 0°C, the Q value will actually decrease. Further, the reason why the heat treatment is performed in an inert gas is that even if the heat treatment is performed in the air, the effect will hardly be exhibited.

The heat treatment time may be about 2 to 6 hours; if the heat treatment is performed for 2 hours or more, the heat treatment effect will appear, and even if the heat treatment is performed for 6 hours or more, the Q value will hardly change.

[Function] When Ba (CoZnNb)0, system dielectric ceramics fired at high temperature in the air are heat treated at an appropriate temperature in an inert gas atmosphere, the dielectric constant G hardly decreases and only the Q value significantly increases. can be improved.

Especially with conventional technology, it lasts for a relatively long time (usually about 20 hours)
Although a high Q+a could not be obtained unless the firing top temperature (approximately 1400° C.) was maintained for a long period of time, according to the present invention, a high Q value can be achieved even when fired in a short time (2 to 3 hours). This significantly reduces firing time.

[Example] (ix)Ba (Co+zaNbtzs)Os +
x B a (Z n+/xN bz/3) Ox
The raw material powders weighed so as to have a predetermined composition expressed by were mixed in a ball mill for 20 hours and calcined at 1100° C. for 6 hours. The obtained calcined powder was again pulverized for 40 hours using a ball mill, dried, and then granulated with the addition of a binder containing PVA (polyvinyl alcohol). The pellets were molded at a pressure of 3 L/cm'' and then fired at 1350 to 1450°C in the atmosphere.

Next, this fired product was heat-treated at 1200 to 1450° C. for 3 hours while flowing nitrogen gas into the furnace (nitrogen gas concentration of 90% or more). For comparison, we also prepared samples that were heat-treated in the air. Then, the dielectric constant ε and the Q value (1/Lan δ) of the dielectric were measured at 6.5 CIIz using the dielectric resonator method for the sample before heat treatment and the sample after heat treatment.

The composition and microwave dielectric properties of some of the prototype samples measured are shown in the table below.

Table In this table, samples marked with * are outside the scope of the present invention. From this measurement result, when comparing before and after heat treatment, it can be seen that although the dielectric constant ε tends to decrease slightly in both cases, it does not substantially change. On the other hand, the Q value can vary greatly.If proper heat treatment conditions within the range of the present invention are satisfied, the firing time is short and even if the Q value before the heat treatment is low, it can be improved by about 2 to 5 times. However, the Q value does not increase even if the heat treatment temperature is too low or too high.

It can be seen that heat treatment in the atmosphere produces almost no heat treatment effect even if it is performed at an appropriate temperature, and that heat treatment effects appear even in products with a high Q value that are fired at high temperatures for a long time.

[Effects of the Invention] As described above, the present invention involves firing Ba(CoZnNb)0-based dielectric ceramics in the air at a high temperature, and then heat-treating them in an inert gas atmosphere at a temperature slightly lower than the firing temperature. This method has an excellent effect in that only the Q value can be significantly improved with almost no decrease in the dielectric constant 8. .

In particular, with the conventional technology, a high Q value could not be obtained unless the firing top temperature (about 1400°C) was maintained for a relatively long period of time (usually about 20 hours), but with the present invention, it is possible to obtain a high Q value in a short time (2 to 3 hours). There is also a high Q for those fired in
This allows the firing time to be significantly reduced, which has the effect of improving productivity and saving energy.

Claims (1)

[Claims] 1, (1-x)Ba(Co_1_/_3Nb_2_/_
3) O_3+xBa(Zn_1_/_2Nb_2_/_
3) A dielectric composition represented by O_3 (0<x<0.75) is fired in the atmosphere, and the resulting porcelain composition is heated to 125
A method for producing a dielectric material for microwave use, which comprises heat-treating in an inert gas atmosphere at 0 to 1400°C.