JP3085625B2 - Dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric porcelain composition comprising dielectric particles and glass, and more particularly to a dielectric porcelain composition applied to electronic circuit boards and electronic components used in a high frequency range. It is about.

[0002]

2. Description of the Related Art Conventionally, various dielectric ceramics have been widely used as dielectric materials for electronic circuit boards and electronic components. In recent years, with the development and spread of high-frequency equipment such as mobile communication represented by mobile phones. Accordingly, dielectric ceramics have been actively used as electronic circuit boards and electronic components used in a high frequency range.

[0003] When simultaneously sintering an electronic circuit board or the like made of the dielectric ceramic and the conductor, the conductor printed on the substrate should not be melted at the firing temperature of the dielectric ceramic so that the conductor is not melted. Having a melting point higher than the firing temperature of dielectric ceramics such as alumina, steatite, and forsterite, for example, Pt, Pd,
Metals such as W and Mo have been used.

However, since the metal has a large conduction resistance, the conventional electronic circuit board has a problem that the resonance circuit and the Q value of the inductance become small, and the transmission loss of the conductor line becomes large. Conventionally, to solve the above-mentioned problems, Ag or C having a small conduction resistance is used.
As a porcelain which employs a metal such as u for a conductor and can be co-fired at a low temperature, a porcelain disclosed in JP-A-59-107596 is known.

The porcelain disclosed in this publication includes glass,
It is disclosed that it is made of quartz glass or the like as a ceramic filler.

[0006]

However, the porcelain composition disclosed in JP-A-59-107596 is used for a multilayer wiring circuit board, and has a frequency of 1 MHz to increase the signal transmission speed of an electronic circuit. Relative permittivity ε _{r at}
Is very small at 5 or less, and the dielectric loss is also large.
It was not at all suitable as a dielectric ceramic composition for electronic parts and the like that require a high dielectric constant and a high Q value.

Conventionally, BaTiO ₃ and CaTiO ₃ have been known as dielectric porcelain compositions having a high relative permittivity. However, when this dielectric porcelain composition is used as a ceramic filler and glass is added thereto, However, even if a filler reacts with glass and a dielectric material having a high relative dielectric constant is used, there is a problem that the relative dielectric constant is reduced.
This is because the filler and the glass react with each other, the crystal structure of the dielectric particles is broken, and characteristics such as a high dielectric constant and a high Q value originally possessed by the dielectric particles cannot be obtained. Such a tendency becomes more remarkable as a large amount of a glass component is added for firing at a lower temperature.Therefore, in the related art, the addition of glass is small in order to maintain a relative dielectric constant and the like, and the firing temperature is also lower than this. It was high.

[0008] The present invention has been made in view of the above problems,
A dielectric porcelain composition containing a relatively large amount of a glass component, which can be fired simultaneously with a conductive metal such as Ag or Cu at a relatively low temperature of 850 to 950 ° C. and suppresses the reaction between glass and a ceramic filler. It is an object of the present invention to provide a dielectric porcelain composition that can be used.

[0009]

Means for Solving the Problems The present inventors have made a dielectric porcelain composition comprising glass and dielectric particles (ceramic filler) whose surface is coated with alumina by an oxide containing at least two metal elements. Found that the reaction between glass and ceramic filler could be suppressed,
The present invention has been made.

That is, the dielectric porcelain composition of the present invention comprises an oxide containing at least two metal elements,
Dielectric particles 30 whose surfaces are coated with alumina
It is composed of 70% by volume and 70 to 30% by volume of glass.

As the dielectric particles, (Mg _0.95 Ca _0.05 ) TiO ₃ and Ba ₂ Ti ₉ used as high frequency materials
Titanates such as O ₂₀ and Ba (Mg _1/3 Ta _2/3 ) O ₃ ,
La (Mg _1/3 Ti _2/3 ) O ₃ -CaTiO ₃ , BaTiO ₃ used as a capacitor material, CaTi
A material containing at least two kinds of metal elements such as O ₃ and SrTiO ₃ is used. However, the material is not limited to the above and may be a conventionally known high dielectric constant material.

According to the present invention, the surface of the dielectric particles is coated with alumina. The coating of alumina is performed, for example, by spraying a solution of aluminum hydroxide on the dielectric particles and heat-treating the same, or by sputtering the dielectric particles.
It is desirable to form it to about 1 μm. By using the dielectric particles coated with alumina in this way, since alumina exists between the dielectric particles and the glass in the sintered body, the dielectric particles do not come into direct contact with the glass and are dispersed. Organization. Thereby, the reaction between the dielectric particles and the glass is suppressed, and a material having a high Q value and a high relative dielectric constant can be obtained.

In the present invention, the amount of dielectric particles in the porcelain composition is limited to 30 to 70% by volume and the amount of glass is limited to 30 to 70% by volume when the dielectric particles are less than 30% by volume ( This is because when the glass content is more than 70% by volume), the firing temperature decreases, and the Q value and the relative dielectric constant decrease. If the dielectric particles are more than 70% by volume (the glass is less than 30% by volume), the firing temperature is 95%.
This is because the temperature rises to 0 ° C. or higher, many voids are generated due to the reaction, and the relative dielectric constant and the Q value decrease. Desirably, the dielectric particles are 40 to 70% by volume, and the glass is 60 to 30% by volume.

The glass used in the present invention desirably has a softening temperature Ts of 1000 ° C. or lower. This is because when the softening temperature Ts is higher than 1000 ° C., the firing temperature of 850 to 950 ° C. This is because it does not become dense. The composition of concrete glass, for example, a SiO ₂ 30 to 80 wt%, B ₂ O ₃ 3-20
Wt%, a BaO 5 to 30 wt%, the Al ₂ O ₃ 3 to 1
There is one containing 0% by weight and 3 to 15% by weight of CaO.

The dielectric ceramic composition of the present invention is used, for example, as an electronic component which itself becomes a capacitor or as a dielectric layer incorporated in a known glass ceramic substrate.
In that case, simultaneous firing with a glass ceramic substrate is also possible.

In the dielectric ceramic composition of the present invention, first, dielectric particles coated with alumina are prepared. For example, BaT
When the dielectric particles made of iO ₃ are coated with alumina, BaCO ₃ and TiO, which are the raw materials of BaTiO ₃ , are used.
₂ is wet-mixed using a ball mill, and after drying this mixture, it is calcined at 1100 to 1400 ° C. for 1 to 4 hours, and crushed to obtain dielectric particles made of BaTiO ₃ .
Such BaTiO ₃ may be commercially available as a raw material from the beginning. Thereafter, a solution of aluminum hydroxide is sprayed on the dielectric particles to form a coating layer of aluminum hydroxide, and then heat-treated at 1000 to 1200 ° C. to coat the dielectric particles with alumina.

The dielectric particles coated with such alumina are mixed with, for example, SiO ₂ , B ₂ O ₃ , and Al ₂ O.
Glass containing _{3 and the} like is added and mixed with the above composition, a binder is added to the mixture, and the mixture is sized.The obtained powder is formed into a predetermined shape by, for example, a doctor blade method or press molding, and is subjected to The binder is removed at 500 ° C. for 2 to 12 hours.
Bake in air or nitrogen atmosphere for 1 to 2 hours.

In the case of baking simultaneously with the conductor, a conductor paste of Ag or Cu may be screen-printed on the surface of the molded body, laminated and pressed as desired, and then fired under the same conditions as above. When co-firing Cu conductors,
It is fired in a nitrogen atmosphere to prevent oxidation.

The present invention comprises dielectric particles coated with alumina and glass. However, impurities mixed from the dielectric particles or glass may be mixed. It may contain elements mixed from balls.

[0020]

According to the dielectric ceramic composition of the present invention, the reaction between the glass and the dielectric particles can be suppressed even when the glass contains a relatively large amount of glass.
It can be fired simultaneously with a conductive metal such as Ag or Cu at a relatively low temperature of 50 ° C., and a high relative dielectric constant can be obtained.

[0021]

EXAMPLES Hereinafter, the dielectric ceramic composition of the present invention will be described in detail based on examples. First, (Mg _0.95 Ca _0.05 )
In order to prepare dielectric particles composed of TiO ₃ , MgCO ₃ , CaCO ₃ and TiO ₂ are prepared as starting materials,
After weighing so that the composition became the above composition, pure water was added and wet mixing was performed for 24 hours using an agate ball. After drying this mixture, it was calcined at 1200 ° C. for 1 hour. Furthermore, using pure water and agate cobblestone, the average crystal grain size was adjusted to an appropriate particle size of 0.5 to 5 μm, and this was used as dielectric particles.

Then, the dielectric particles were sprayed with a solution of aluminum hydroxide and heat-treated at 1000 ° C. to coat the dielectric particles with alumina.

A borosilicate glass containing 50% by weight of SiO ₂ , 10% by weight of B ₂ O ₃ , 25% by weight of BaO, 5% by weight of Al ₂ O ₃ and 12% by weight of CaO (softening temperature) (Ts 800 ° C.) was prepared, and the above-mentioned dielectric particles and borosilicate glass were weighed so that the ratio was as shown in Table 1. Then, pure water was added, and wet mixing was performed using an agate ball for 24 hours. About 1% by weight of polyvinyl alcohol was added as a binder to this mixture, and the mixture was sized.
Press molding was performed under a pressure of on / cm ² to produce a cylindrical molded body having a diameter of 20 mm and a height of 10 mm without distortion. Thereafter, the molded body was subjected to a binder removal treatment at 400 ° C. for 4 hours, and was further baked at a temperature shown in Table 1 for 30 minutes in the air.

The obtained porcelain was ground and polished to obtain a sample. Using this sample, the dielectric constant and the Q value are measured at a resonance frequency of 6 GHz by the dielectric cylinder resonator method, and the temperature change of the resonance frequency in a temperature range from -40 to + 85 ° C. is measured. The temperature coefficient (τf) was calculated. The results are shown in Table 1.

[0025]

[Table 1]

From the results shown in Table 1, the dielectric ceramic composition of the present invention can be fired at 850 to 950 ° C., has a relative dielectric constant of 9.5 or more, a Q value of 580 or more,
The temperature coefficient (τf) was within 0 to 5 ppm / ° C., and the sintered body itself had a good void state.

Incidentally, the inventors of the present invention have obtained the samples No. 2 to No. 2.
As a result of examining dielectric particles of Sample No. 6 using an X-ray diffractometer, it was confirmed that almost all phases of the dielectric particles remained, and it was confirmed that the glass and the dielectric particles did not react.

As a comparative example, when a sample not coated with alumina (sample No. 8) was prepared, the relative dielectric constant was low, and the Q value was too low to measure.

Example 2 The present inventors set the dielectric particles in Example 1 to B
An experiment was performed in the same manner as in the above example, except that a (Mg _1/3 Ta _2/3 ) O ₃ and Ba ₂ Ti ₉ O ₂₀ were used. The results are shown in Table 1.

The dielectric particles are made of BaTiO ₃ , Ca
An experiment was performed in the same manner as in the above example except that TiO ₃ and SrTiO ₃ were used. The results are shown in Table 2.

[0031]

[Table 2]

Incidentally, BaTiO ₃ , CaTiO ₃ , SrT
Since iO ₃ was used as a capacitor material, the temperature coefficient (τf) was not measured.

From these Tables 1 and 2, the dielectric ceramic composition of the present invention can be fired at 850 to 950 ° C., can obtain a high relative dielectric constant, and has a void state of the sintered body itself. Was also good.

[0034]

The dielectric porcelain composition of the present invention has a composition of 850 to 850.
At a relatively low temperature of 950 ° C., it can be fired simultaneously with a conductive metal such as Ag or Cu, and furthermore can suppress the reaction between glass and dielectric particles to obtain a high relative dielectric constant. And high performance can be realized. It also has excellent characteristics as a capacitor material.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Nobuyoshi Fujikawa 1-4-4 Yamashita-cho, Kokubu-shi, Kagoshima Examiner at Kyocera Research Institute Yuichi Fukakusa (56) References JP-A-6-345530 (JP, A) JP-A-4-193762 (JP, A) JP-A-63-151645 (JP, A) JP-A-61-31342 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/14-35/495

Claims (1)

(57) [Claims] The present invention relates to: an oxide containing at least two kinds of metal elements, the surface of which is made of 30 to 70% by volume of dielectric particles coated with alumina and 70 to 30% by volume of glass. Characteristic dielectric porcelain composition.