JPH02225357A - Complex dielectric material - Google Patents

Abstract

PURPOSE:To form a complex dielectric material having sufficient relative, permittivity, low dielectric loss and excellent utility by blending inorganic dielectric material powder with particulate surface coated with an electroconductive substance with a resin. CONSTITUTION:This complex dielectric material 1 consists of inorganic dielectric material powder 2 and a resin 3 and the surface of practicles 2 of the inorganic dielectric material powder is partially coated with an electroconductive substance 2a. The electroconductive substance 2a is electroconductive powder and is preferably stuck to the surface of the particles 2 of the inorganic dielectric material powder with the same resin for constituting the dielectric material. Metallic powder, carbon powder or semiconductor powder may be cited as the electroconductive powder. Electroconductive needle-like powder 4 may be used instead of the electroconductive powder 2a and a complex dielectric material 1' is produced from the electroconductive needle-like powder, the inorganic dielectric material powder 2 and the resin 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a composite dielectric consisting of an inorganic dielectric powder and a resin.

[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.

Under these circumstances, with remarkable progress in microwave semiconductor devices and microwave integrated circuit technology, there has recently been an increasing demand for miniaturization of dielectric substrates used as microwave circuit boards.

Usually, a ceramic substrate is often used as the dielectric substrate. The most popular ceramic substrate is an Al x Os substrate. This is because although the dielectric constant is somewhat small (9, 8), it is larger than that of a normal resin substrate, and is advantageous in terms of device miniaturization and electromagnetic wave leakage.

In microwave semiconductor devices, the size of the device 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, there is a relationship of λ-λJεr6s. Therefore, the higher the relative dielectric constant of the dielectric substrate used, the smaller the element becomes.Furthermore, the higher the relative permittivity, the more convenient the electromagnetic energy is concentrated within the substrate, and the leakage of electromagnetic waves is reduced. .

However, the above-mentioned ceramic substrates are not easy to perform post-processing (drilling and cutting), require additional pressure bonding of the heat sink, and have low productivity (difficult to increase the area, so when making a circuit board, many There are problems such as (the number of individual pieces is small).

Composite dielectrics have been proposed to solve these problems. For example, composite dielectrics made of inorganic dielectric powder and resin (organic resin) have been proposed.

The composite dielectric material used as the dielectric material for circuit boards has a suitably large dielectric constant (εr-10 to 3
Specifically, the following composite dielectric materials have been proposed, which are required to have a low dielectric loss (approximately 0) and low dielectric loss in the microwave region.

(1) Composite dielectric material made by mixing resin and (granular) carbon powder (Japanese Patent Publication No. 55-2044).

■ Composite dielectric material consisting of 4M resin and inorganic dielectric powder (JP-A-62-200603, JP-A-63-8630)
9, JP-A-63-259903) Composite dielectric material made by mixing resin, inorganic dielectric powder and (granular) carbon powder (JP-A-57134806)
.

[Problem to be solved by the invention]

However, the above composite dielectric materials (1) to (4) lack practicality in the following points.

Although the dielectric constant of (2) increases, the dielectric loss is too large. ■The composite dielectric has a high dielectric constant g! ＃The relative dielectric constant is not as high as expected despite the addition of powder. The composite dielectric material (2) still has no improvement in dielectric loss and is not very practical.

In view of the above circumstances, this invention has a sufficient dielectric constant,
The object of the present invention is to provide a composite dielectric material that has low dielectric loss and is highly practical.

[Means to solve the problem]

In order to solve the above problems, the composite dielectric material according to claims 1 to 5 has the following configuration.The composite dielectric material 1 according to claim 1, as shown in FIG. 2・
... and a resin 3, and as shown in FIG. 2, a conductive material 2a is partially attached to the surface of two particles of inorganic dielectric powder.

In the dielectric of this invention, for example, claim 2 is applied to a conductive material.
As in the composite dielectric described above, conductive powder is used, and this powder is attached to the surface of the inorganic dielectric powder particles using the same resin as the matrix resin (resin for forming the dielectric).

As the conductive powder, at least one selected from metal powder, carbon powder, and semiconductor powder is used, for example, as in the composite dielectric of the third aspect.

As shown in FIG. 3, the composite dielectric 1' of claim 4 includes conductive acicular powder 4 along with inorganic dielectric powder 2 and resin 3.
The structure also includes

In addition, the composite dielectric according to the fifth aspect uses Tiat powder as the inorganic dielectric powder 2.

Examples of the resin constituting the composite dielectric of claims 1 to 5 include Teflon resin, polyimide resin, epoxy resin, polyester resin, polyethylene resin, and PPO resin.
(polyphenylene oxide) resin, PVDF (polyvinylidene fluoride) resin, and the like.

On the other hand, the inorganic dielectric powder particles are PbTixZr+-X
Ox, PbTiOs, Tilt, BaTi01,
Examples include PbNb06, barium titanate compositions modified to improve temperature and frequency dependence, and various three-component perovskite compositions.

Specifically, examples of conductive powder for conductive objects include A, 6 powder (metal powder), graphite powder (carbon powder), tin oxide powder (semiconductor powder), zinc oxide powder (semiconductor powder), etc. Can be mentioned. A plurality of these powders may be used in combination.

The above conductive powder is physically and chemically attached (bonded) to the surface of the inorganic dielectric powder particles either alone or in combination with a resin.
I am made to do so. In particular, it is preferable to use the same resin as the matrix resin to make the conductive material more difficult to peel off. However, metal powder tends to be relatively strongly adhered (bonded) to the surface of inorganic dielectric powder particles even without the use of resin.

Examples of the conductive acicular powder added in the composite dielectric according to claim 4 include carbon fibers, metal fibers, SiC whiskers, and the like. These conductive acicular powders usually have an average particle length in the range of about 10 to 100 u and an average particle size in the range of about 0.1 to lcjttm. If the acicular conductive powder particles added are too short, the ability to electrically connect between the inorganic dielectric powder particles will be weak, and on the other hand, if they are too long, the insulation properties and breakdown voltage will be greatly reduced.

The addition ratio of the conductive acicular powder is as follows, assuming that the total amount of the inorganic dielectric powder, resin, and conductive acicular powder is 100% by volume.
Preferably in the range of 0.1 to 20% by volume, 0.
If the amount is less than 1% by volume, there is no effect of addition, and if it exceeds 20% by volume, problems such as excessive reduction in insulation properties and breakdown voltage, and excessively large dielectric loss tend to occur.

Further, in the composite dielectric of the present invention, the blending ratio (volume ratio) of the resin and the inorganic dielectric powder is usually within the above ratio range.

Resin: Dielectric powder -9: ] ~ 2:8 Of course, it goes without saying that the composite dielectric according to the present invention is not limited to the resins and powders exemplified above, or those in the numerical range. The dielectric may contain other components for improving properties in addition to inorganic dielectric powder, resin, or conductive nail powder.

Further, although the composite dielectric of the present invention is a suitable material for circuit boards, it goes without saying that it may be used for other purposes.

[For production]

In the composite dielectric material according to claims 1 to 3, a conductive material is partially attached to the surface of the inorganic dielectric powder/non-particles. This conductive material acts as a so-called low-resistance electrode that connects adjacent inorganic dielectric powder particles in parallel in the composite dielectric, and thereby the high dielectric inorganic dielectric powder is fully utilized and the entire composite dielectric is Assume that the dielectric constant is high.

In the composite dielectric material according to claim 4, the conductive acicular powder particles act to connect the plurality of inorganic dielectric powder particles in parallel, whereby the highly dielectric inorganic dielectric powder is fully utilized, and the composite The dielectric constant as a whole is set to be high.

Conventionally, inorganic dielectric powder (for example, 13 a Ti O! powder) with a uniform particle size of 1 to 2 μm has been used. In this case, assuming that each inorganic dielectric powder is one capacitor, Many capacitors were connected in series, resulting in a lower dielectric constant. On the other hand, in the composite dielectric of the present invention, the series coupling is reduced and the parallel coupling is increased, so that the dielectric constant becomes high.

Since the above-mentioned conductive material and conductive acicular powder effectively increase the dielectric constant even in small amounts, the addition of conductive powder does not cause an increase in dielectric loss as in the conventional case.

When the inorganic dielectric powder is a single-component titanium oxide (especially rutile titanium oxide) powder, it has stable capacitance-frequency characteristics and capacitance-temperature characteristics, compared to multi-component powders. It has excellent performance stability and is inexpensive.

〔Example〕

Examples and comparative examples of composite dielectrics according to the present invention will be described below.

Example 1 First, inorganic dielectric powder was created as follows.

B a T i *, ? 4 Z r m,!
a Ot composition, BaC0t, TiO
x s Zr0z was weighed and blended, wet pulverized and mixed with water using a pot mill, dried, and then fired at 1300° C. for 1 hour in a zirconia crucible to obtain a fired product having the above composition. This fired product is first coarsely ground in an ultra-hard mortar, then wet-ground using a zirconia pot and zirconia balls until the particle size becomes 7 to 15 μm (average Ion), and then dried. Dielectric powder was created. Note that this ceramic dielectric powder itself has εr = 7000 (25°C) tan δ = 1.3% (
25°C).

Next, the inorganic dielectric powder was added to 99% by volume and 0.1μ
0.7% by volume of graphite powder with a particle size of 0.7% or less.
Add 0.3% by volume of PPO resin (resin for attaching conductive substances) finely pulverized to 3 μm or less, and use a hybridization system manufactured by Nara Kikai Seisakusho to partially attach conductive substances to the particle surface. 1n (mechanical dielectric powder was obtained).

The inorganic dielectric powder thus obtained and the PPO resin were mixed at a volume ratio of 1:3. This mixture was set in a mold, molded at a temperature of 230° C. and a pressure of 20 kg/c+J, and cooled to room temperature while the pressure was applied to obtain a composite dielectric. The mixture in the mold was set between Cu foils so that the Cu foils were bonded to both sides of the completed composite dielectric.

Example 2 A composite dielectric was obtained in the same manner as in Example 1, except that the blending ratio (volume ratio) of PPO resin and inorganic dielectric powder was 1=1.

Example 3 97% by volume of inorganic dielectric powder, 2% by volume of graphite powder with a particle size of 0.1 μm or less, and 1% by volume of PPO resin finely pulverized to 0.3 μm or less were added. A composite dielectric material was obtained in the same manner as in Example 1, except that a conductive substance was partially attached to the particle surface using a hybridization system manufactured by A.

Example 4 98% by volume of inorganic dielectric powder, 2% by volume of AI powder with a particle size of 0.1 tr* or less in place of graphite powder
A composite dielectric material was obtained in the same manner as in Example 1, except that the conductive material was partially attached to the particle surface using a hybridization system manufactured by Nara Kikai Seisakusho.

Example 5 - 97% by volume of inorganic dielectric powder, replaced with graphite powder, and 2% by volume of 3nO powder (Mitsubishi Metals @M) with a particle size of 0.1 μm or less, finely divided into 0.3p or less. crushed PP
A composite dielectric material was prepared in the same manner as in Example 1, except that 1% by volume of O resin was added and a conductive material was partially attached to the particle surface using the hybridization system manufactured by Nara Kikai Seisakusho. Obtained.

Example 6- First, inorganic dielectric powder was created as follows.

1 wt % (PVA is calculated as solid content) of PVA melt was added to rutile type titanium oxide powder (average particle size 0.2 n), and water was added to adjust the slurry to have a viscosity of 1 QQ cps. Using a spray dryer, this slurry is
vomit? , adjust the pressure, drying temperature, and air volume to obtain a particle size of 20~
A dry powder of 50 μm was obtained. This dry powder was fired and sintered in an aluminum crucible at a temperature of 1200° C. for 2 hours. At this time, sintering shrinkage occurs internally, but the bonding between powder particles is slight, and the fired product is ground in an alumina pot for about 1 hour to finally create titanium oxide powder with a size of 8 to 35μ. did.

Next, the inorganic dielectric powder was added to 95% by volume and 0.1μ
4% by volume of graphite powder with a particle size of less than l, 0.3u
Titanium oxide powder was added with 1% by volume of finely pulverized PPO resin (resin for attaching conductive objects) to the following, and a conductive material was partially attached to the particle surface using a hybridization system manufactured by Nara Kikai Seisakusho. I got it.

The resulting powder was then mixed in volume proportions with an equal amount of PPO resin. This mixture was set in a mold and molded at a temperature of 230° C. and a pressure of 20 kg/c11, and cooled to room temperature while the pressure was applied to obtain a composite dielectric. In addition, the mixture was set between Cu foils in the mold, and Cu was bonded to both sides of the completed composite dielectric.

Example 7 A composite dielectric was obtained in the same manner as in Example 6, except that the blending ratio (volume ratio) of PPO resin and titanium oxide powder was 1:2.

Example 8 - 90% by volume of titanium oxide powder, 8% by volume of graphite powder with a particle size of 0.1 μm or less, and 2% by volume of PPO resin finely ground to 0.3 μm or less, - Nara A composite dielectric material was obtained in the same manner as in Example 6, except that a conductive substance was partially attached to the particle surface using a machine manufacturing type hybridization system.

Example 9 - 95% by volume of titanium oxide powder was replaced with graphite powder with a particle size of 0.1 μm or less! A composite dielectric was obtained in the same manner as in Example 6, except that 5% by volume of powder was added and a conductive substance was partially attached to the particle surface using a hybridization system manufactured by 01 Nara Kikai Seisakusho. Ta.

Example IO Titanium oxide powder was replaced with 95% by volume and graphite powder was replaced with 0.0% by volume. Pr is 4.5% by volume of conductive 5nO8 powder with a particle size of I ttm or less, finely pulverized to 0.3 us or less.
A composite dielectric was prepared in the same manner as in Example 6, except that 0.5% by volume of o resin was added, and a conductive material was partially attached to the particle surface using a Nara Kikai Seisakusho type hybridization system. Example 11: First, an inorganic dielectric powder was prepared as follows.

% Bacon , Ties , Zr0 so that the composition becomes B a T i #, FA Z r *, zaOz
t was weighed and blended, water was added and wet pulverized using a bot mill, and after drying, 1 was mixed in a zirconia crucible.
Firing was performed at 300°C for 1 hour, and the fired product with the above composition was
%is. This fired product is first coarsely ground in an ultra-hard mortar, then wet-ground using a zirconia bot and zirconia pole until the particle size is 7 to 15 μl (average 10 μl), and dried to produce an inorganic dielectric powder. It was created. In addition,
This ceramic dielectric powder itself has tr = 7000
(25°C) and tan δ = 1.3% (25°C).

On the other hand, carbon fiber was finely pulverized using a Raikai machine to separately prepare conductive acicular powder having a length of about 50 to 100 IJl and a diameter of about 5 to 10 f@.

Next, 1 volume % of conductive acicular powder made of carbon fiber and 50 volume % of PPO resin were added to 49 volume % of the inorganic dielectric powder, and a rocking mixer was used to maintain the particle size as much as possible. Thoroughly mixed and crushed.

This mixture was placed in a mold at a temperature of 230°C for 2 hours.
0kg/co! A composite dielectric material was obtained by molding the material under a pressure of The mixture was set between Cu foils in the mold, and Cu was bonded to both sides of the resulting composite dielectric.

Example 12 - A composite dielectric was produced in the same manner as in Example 11, except that 5 volume % of conductive acicular powder made of carbon fiber and 50 volume % of PPO resin were added to 45 volume % of inorganic dielectric powder. I got it.

Example 13 - SiC whiskers (approximately 50 to 100μ in length,
A composite dielectric material was obtained in the same manner as in Example 11, except that 5% by volume of conductive acicular powder (with a diameter of approximately 0.1 to 1 μm) and 50% by volume of PPO resin were added.

Comparative Example 1 A composite dielectric was obtained in the same manner as in Example 1, except that no conductive material was attached to the surface of the inorganic dielectric powder particles.

Comparative Example 2 A composite dielectric was obtained in the same manner as in Example 6, except that no conductive substance was attached to the surface of the inorganic dielectric powder particles.

Comparative Example 3 A composite dielectric was obtained in the same manner as in Example 11, except that the inorganic dielectric powder particles were 50% by volume and the PPO resin was 50% by volume (no conductive acicular powder was added).

Comparative Example 4 - Inorganic dielectric powder particles and PP resin were mixed at a volume ratio of 1:3, and granular graphite powder was added in an amount of 3% by volume instead of conductive acicular powder. Example 1
A composite dielectric material was obtained in the same manner as in Example 1.

Examples 1-13 and Comparative Examples 1-
The relative dielectric constant εr and dielectric loss characteristics (dielectric loss tangent; tan δ) of the composite dielectric material No. 4 were measured. Note that the measurement frequency is IGh, and the ambient temperature during measurement is 25°C.

The measurement results are shown in Tables 1 to 3.

The composite dielectrics of Examples 1 to 13 in Table 1.2 all have sufficient dielectric constants. The composite dielectric of Example 1 has a significantly higher dielectric constant than the corresponding composite dielectric of Comparative Example 1, and the composite dielectric of Example 6 has a significantly higher dielectric constant than the corresponding composite dielectric of Comparative Example 2. After all, the dielectric constant is extremely high, which clearly shows that attaching a conductive substance to the surface of the inorganic dielectric powder particles brings about an improvement in the dielectric constant. Further, the composite dielectric of Example 11 has a significantly higher dielectric constant than the corresponding composite dielectric of Comparative Example 3, and the addition of the conductive acicular powder brings about an improvement in the dielectric constant. It clearly shows that. Furthermore, the composite dielectric materials of each example have a dielectric loss tangent of 1% or less, which is lower than that of the conventional composite dielectric material using granular carbon powder (Comparative Example 4), and the dielectric loss characteristics are within a range that does not impair practicality. It is also clear that there is

〔Effect of the invention〕

As mentioned above, in the composite dielectric of the present invention, a conductive substance is partially attached to the surface of the inorganic dielectric powder particles, or conductive acicular powder is added, so that the composite dielectric material of the present invention is sufficiently It has a high relative dielectric constant and low dielectric loss, making it highly practical.

[Brief explanation of the drawing]

FIG. 1 is a schematic illustration of an example of the composite dielectric of claim 1, FIG. 2 is a schematic illustration of inorganic dielectric powder particles of this composite dielectric, and FIG. Claim 4
FIG. 2 is an explanatory diagram schematically showing an example of a composite dielectric material. l, 1'... Composite dielectric 2... Inorganic dielectric powder 2a... Conductive material 3... Resin 4... Conductive acicular powder Agent Patent attorney Takehiko Matsumoto

Claims (1)

[Scope of Claims] 1. A composite dielectric comprising an inorganic dielectric powder and a resin, characterized in that a conductive material is partially attached to the surface of the inorganic dielectric powder particles. . 2. The composite dielectric material according to claim 1, wherein the conductive material is a conductive powder, and is adhered to the surface of the inorganic dielectric powder particles using the same resin as the resin for forming the dielectric material. 3. Claim 2, wherein the conductive powder is at least one selected from metal powder, carbon powder, and semiconductor powder.
Composite dielectric as described. 4. A composite dielectric comprising an inorganic dielectric powder and a resin, the composite dielectric comprising also conductive acicular powder. 5. The composite dielectric material according to any one of claims 1 to 4, wherein the inorganic dielectric powder is TiO_2 powder.