JPH03216910A - Composite dielectric and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain sufficient dielectric constant with a composite dielectric in which inorganic dielectric powder is dispersed in plastic by distributing the dielectric over an entire area of the dielectric in a state where the inorganic dielectric powder is distributed locally at a high density. CONSTITUTION:In a composite dielectric in which inorganic dielectric powder 1 is dispersed in resin 2, the amount of the powder 1 connected in straight lines in the resin 2 is larger in the case the inorganic dielectric powder 1 is dispersed with locally high density than the in the case the powder 1 is uniformly dispersed. As a result, the dielectric constant is higher than conventional dielectrics containing the same amount of additive of the dielectric powder because of increased amount of the inorganic dielectric in the form of electrically parallel connections. This causes the inorganic dielectric powder 1 mixed in to be utilized more effectively to contribute to the increase in the dielectric constant.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a composite dielectric and a method for manufacturing the same.

[Conventional technology]

As we enter the advanced information age, information transmission tends to become faster and more frequent. Mobile radios such as car telephones and personal radios, new media such as satellite broadcasting, satellite communications, and CATV are also at the stage of practical application.

On the other hand, in mobile radio and media, devices are becoming more compact, and along with this, there is a strong demand for smaller microwave circuit elements such as dielectric resonators.

The size of a microwave circuit element is based on the wavelength of the electromagnetic waves used. The wavelength λ of an electromagnetic wave propagating in a dielectric material with relative permittivity εr is the propagation wavelength in vacuum. Then, λ−λ
. /ε becomes 05. Therefore, the larger the dielectric constant of the circuit dielectric substrate used, the smaller the element becomes.

Further, when the relative dielectric constant of the dielectric substrate is large, electromagnetic energy is concentrated within the substrate, which is advantageous in that leakage of electromagnetic waves is small.

As a dielectric material, for example, AJ. O, there is a ceramic dielectric. Compared to resin, it has the advantage of having a high dielectric constant and low dielectric loss. However, this dielectric material has problems in that it is not sufficient in terms of large area, cost, processability such as cutting and drilling, and multilayering.

Therefore, a composite dielectric material in which inorganic dielectric powder is dispersed in a resin has been proposed as a dielectric material that does not have the problems of increasing the area, cost, processability such as cutting and drilling, and multilayering.

The inorganic dielectric powder is blended to compensate for the low dielectric constant of the resin.

[Problem to be solved by the invention]

However, the problem with this composite dielectric is that the inorganic dielectric powder does not function adequately. It does not effectively serve to provide a suitably large dielectric constant suitable for dielectric substrates. Note that the relative dielectric constant of the composite dielectric for the substrate is an appropriate value (for example, from about 10 to 30
The reason for this is that if the dielectric constant is too large, the required width of the circuit becomes too narrow, making processing for forming the circuit difficult.

PPO resins and fluororesins with low loss (tan δ) in the high frequency range have extremely low dielectric constants (εr=2.0 to 3.
2). The inorganic dielectric powder itself has a sufficient dielectric constant and should contribute to improving the dielectric constant of the entire composite dielectric, but within this composite dielectric, the inorganic dielectric powder dispersed in the resin has a low dielectric constant. Because the resin is connected in series,
It does not exhibit a sufficient dielectric constant improving effect.

In view of the above circumstances, the first object of this invention is to provide a composite dielectric material in which a high dielectric constant inorganic dielectric powder effectively exhibits a dielectric constant improving effect and has a sufficient dielectric constant. The second object is to provide a method that can easily manufacture a composite dielectric.

[Means to solve the problem]

In order to solve the first problem, a composite dielectric in which an inorganic dielectric powder is dispersed in a resin according to the invention according to claim 1 is provided, in which the inorganic dielectric powder is locally present at high density. It has a configuration in which it is distributed over the entire area in a state where

In order to solve the second problem, in the method for obtaining a composite dielectric in which inorganic dielectric powder is dispersed in a resin according to the invention as claimed in claim 2, at least a part of the surface is covered with inorganic dielectric powder. The resin powder to which it is densely adhered is melted and hardened.

The resin used in this invention (for matrix) is:
Examples include PPO resin, fluororesin (for example, polyphtholated ethylene resin commonly known as Teflon), polycarbonate, polyethylene, polyethylene terephthalate, polypropylene, polystyrene, and the like. The relative permittivity εr of these resins is usually 2. It is about 0 to 3.2.

Examples of the inorganic dielectric powder used in this invention include:
B a TiO s system, SrTiO, system, TiO2
system, PbT L. Examples include ceramic dielectric powders such as sZre, sOt, etc., and in particular, those having a dielectric constant of 30 or more and a particle size of about 0.05 to 10μ1 are used.

In addition to resin and inorganic dielectric powder, a reinforcing sheet made of glass fiber (glass cloth, glass cloak, etc.) or inorganic fiber (glass fiber, etc.) may be used in combination.

In the case of a sheet, the thickness is usually about L5n to 2H, and the glass fiber diameter is about 0.5 to 20μ1. In the case of fibers, the length is usually about 20 to 300 microns, and the diameter is usually about 0.5 to 20 microns.

The composite dielectric of the present invention can be manufactured, for example, as follows.

First, as shown in Fig. 2, resin powder (about 1 to 200μ) 2' and inorganic dielectric powder 1... are mixed in a liquid and then dried to form an inorganic dielectric on the surface of the resin powder. Body powder k・Densely adhere.

Since the resin powder may aggregate during the drying stage and become powdered, a pulverization process may be introduced as necessary to re-powder (10 to 3
000μ wealth) in some cases.

Note that the inorganic dielectric powder does not need to be attached to cover the entire surface of the resin powder, and the inorganic dielectric powder may be densely attached to only a part of the surface.

Thereafter, by melting and hardening the resin powder to which the inorganic dielectric powder is attached, a composite dielectric is obtained.

The compounding ratio of matrix resin, inorganic dielectric powder, and reinforcing material used as necessary in the composite dielectric is usually resin: 25 to 94 voJ% (volume %), inorganic dielectric powder: l
~10 vol% (preferably 50 vol% or less), reinforcing material: 5-50 vol%! %. The larger the amount of inorganic dielectric powder, the higher the dielectric constant, but if the amount is too large, strength etc. tend to decrease.

It goes without saying that this invention is not limited to the compounds or numerical ranges exemplified above.

[For production]

As shown in FIG. 1, when the composite dielectric material of claim 1 is dispersed in a locally high density state and distributed over the entire area, as shown in FIG. Powder 1 is arranged in a straight line and connected in resin 2.
... increases, and as a result, more inorganic dielectrics are connected in parallel in terms of electric circuits, so the dielectric constant becomes higher with the same addition amount as before. In other words, the mixed inorganic dielectric powder effectively contributes to improving the dielectric constant.

In the composite dielectric of claim 2, compared to the conventional method, it is sufficient to prepare resin powder and sprinkle the same powder with inorganic dielectric powder, so that a composite dielectric with excellent dielectric constant can be easily obtained. become.

〔Example〕

Next, an example of obtaining the composite dielectric material according to claim 1 using an example of the manufacturing method according to claim 2 will be described in detail.

Example 1 PPO resin (with specific gravity of 1.06 and particle size of 10n) at room temperature
Toluene (500v01%) was added to 70vo/% polyphenylene oxide (polyphenylene oxide) powder, and while stirring, 30vOl% 13a TiO* powder with an average particle size of 2μ was added. At room temperature, the surface of the PPO resin powder is only slightly dissolved in toluene, so the BaTiO powder sticks around the PPO resin powder. Then, after evaporating the toluene at 150°C, pulverizing it to less than 16 mesosh,
Using a mold with a diameter of 6 (1+ m), molding was carried out at 250° C. for 10 minutes at a pressure of 39 kg/cnl, and the temperature was lowered to room temperature while being kept under pressure to obtain a composite dielectric.

Comparative Example 1 Using trichlene instead of toluene, PPO41 fat powder was dissolved in trichlene and BaTiO. A composite dielectric was obtained in the same manner as in Example 1, except that the powder was uniformly dispersed.

Example 2 - PPO resin powder 50vo/%, BaTiO, powder 50v
A composite dielectric material was obtained in the same manner as in Example 1 except that the ol% was changed.

Comparative Example 2 PPO resin powder 50vo1%, Ba'l"ion powder 5
A composite dielectric material was obtained in the same manner as in Comparative Example 1 except that 0vo6% was used.

Example 3 PPO resin powder 70νOl% of Example 1 and Example 1
30voJ% of BaTiOs powder was mixed in a dry method, and then BaT was added to the PPO resin powder at 6400 rom/min using a surface modification device (Nara Kikai NHSl).
iOs powder was deposited. After this, a composite dielectric was obtained in the same manner as in Example 1.

Example 4 PPO resin powder 50voj2%, BaTiOs powder 50
A composite dielectric material was obtained in the same manner as in Example 3 except that voβ% was used.

A conductive paste was applied to the front and back surfaces of each composite dielectric of Examples and Comparative Examples and dried to form electrodes, and dielectric properties were measured using an impedance analyzer (IMHz 0
．． 5V measurement condition). The results are shown in Table 1.

Table 1 Comparing Example 1 and Comparative Example 1 and Example 2 and Comparative Example 2,
It is clearly seen that in the composite dielectric obtained by this invention, the inorganic dielectric powder effectively contributes to improving the dielectric constant. All of the composite dielectrics of the examples have relative dielectric constants of about 10 or more, which are suitable for use as dielectric substrates for high frequencies, and losses (tan δ) are well within the practical range.

〔Effect of the invention〕

As described above, in the composite dielectric according to claim 1, since the inorganic dielectric powder is dispersed in a state where the inorganic dielectric powder is locally present at high density and distributed over the entire area, the mixed inorganic dielectric powder The powder effectively contributes to improving the dielectric constant.

According to the method for manufacturing a composite dielectric according to the second aspect, the excellent composite dielectric described above can be easily manufactured.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram schematically showing an example of the composite dielectric material of claim 1, and FIG. 2 is an explanatory diagram schematically showing an example of the method of manufacturing the composite dielectric material of claim 2, in which an inorganic dielectric material is attached to resin powder. FIG. 2 is an explanatory diagram schematically showing the situation. l...Inorganic dielectric powder 2...Resin 2'...Resin powder

Claims (1)

[Claims] 1. In a composite dielectric material in which an inorganic dielectric powder is dispersed in a resin, the inorganic dielectric powder is dispersed so as to be locally present at high density and distributed over the entire area. A composite dielectric material characterized by: 2. A method for obtaining a composite dielectric material in which an inorganic dielectric powder is dispersed in a resin, characterized by melting and hardening a resin powder having an inorganic dielectric powder closely adhered to at least a part of its surface. A method for manufacturing a composite dielectric material.