JPH0733516A - Mgo-sio2 porcelain and its production - Google Patents

Abstract

PURPOSE:To produce an/MgO-SiO2 porecelain having excellent electric properties by obtaining the mixed sintered product of a forsterite phase and/or an enstatite phase. CONSTITUTION:This MgO-SiO2 porcelain comprises a dense mixed sintered product having a forsterite phase and/or an enstatite phase and having an MgO/ SiO2 molar ratio of 2.5/1 to 2/1.7, a dielectric constant of 6.4-7.5 and a dielectric dissipation factor of <=1X10<-4>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixed sintered body of forsterite phase and / or enstatite phase, and more specifically, it has a molar ratio of MgO and SiO ₂ of 2.5: 1 to 2: 1. high purity MgO-SiO ₂ systems for porcelain and a manufacturing method thereof was varied range.

[0002]

_2. Description of the Related Art Conventionally, forsterite (2MgO.SiO) has been known as a typical MgO-SiO ₂ porcelain.
₂ ) There are porcelain and steatite (MgO.SiO ₂ ) porcelain, both of which have a low dielectric loss tangent and are used as insulating materials in the high frequency range as low loss dielectric materials and substrate materials. Among these, for the forsterite porcelain, it has been confirmed by the present inventors that the electrical characteristics can be further enhanced by obtaining a high-purity forterite porcelain using a high-purity raw material.

[0003]

With respect to steatite porcelain, however, since it is not possible to obtain a sintered body which is difficult to sinter, has high purity, and is dense, it is possible to obtain steatite porcelain with further improved electrical characteristics. Was difficult. Also, while steatite porcelain and forsterite porcelain are both excellent in electrical properties, they are also sintered bodies with their respective characteristics, and by taking advantage of the electrical properties of both, we obtain more electrically superior porcelain. Is desired. Furthermore, even in high-purity porcelain, it is necessary to obtain appropriate electrical characteristics according to the application of the porcelain.

Therefore, it is an object of the present invention to provide a MgO-SiO ₂ system porcelain having excellent electrical properties by obtaining a hybrid sintered body with a forsterite phase and / or an enstatite phase. . The present invention also aims to provide a method for manufacturing a MgO-SiO ₂ based ceramic capable of obtaining a proper electrical properties according to the application which is excellent in electrical properties.

[0005]

In order to solve the above-mentioned problems, the present inventors have forsterite (2MgO.S)
As a result of searching synthetic conditions of synthetic porcelain powder of MgO—SiO ₂ composition around the iO ₂ ) composition and sintering conditions of these synthetic porcelain powder molded products, it is possible to obtain a dense and excellent electrical property without lowering sinterability. They have found that a sintered body can be manufactured. That is, as a means for solving the above-mentioned problems, the present inventors have found that the forsterite phase and / or
Alternatively, it is a dense hybrid sintered body having an enstatite phase, the molar ratio range of MgO and SiO ₂ is 2.5: 1 to 2: 1.7, and the relative dielectric constant is 6.4 to 7.5. Dielectric loss tangent is 1
MgO—SiO ₂ characterized by having a value of × 10 ⁻⁴ or less
I created a series of porcelain.

Further, the impurities contained in the hybrid sintered body
Thing is Al₂O₃0.50% (meaning% by weight
To do. same as below. ) Or less, CaO 0.50% or less,
Fe ₂O₃0.50% or less, Na₂O 0.50% or less
Below, ZrO₂ Characterized by being 0.50% or less
MgO-SiO₂I created a series of porcelain.

In order to solve the above-mentioned other problems,
As means, (1) MgO powder and SiO₂Powder or Si
O₂The colloidal solution is MgO and SiO₂Has a molar ratio of 2.
Mixing and baking in the range of 5: 1 to 2: 1.7;
(2) The calcined powder obtained in the above step is powdered to have an average particle size of 3 μm or less.
Crush and MgO-SiO ₂A step of making a system synthetic powder,
(3) This MgO-SiO₂Pressure-forming synthetic powder
Forsterite and / or en
MgO-SiO with statite composition₂Process to make system porcelain,
MgO-SiO characterized by comprising₂Porcelain
Created a manufacturing method. Furthermore, this MgO-SiO₂system
In the method of manufacturing a porcelain, MgO-SiO₂Included in system porcelain
The impurities₂O₃0.50% or less, CaO
 0.50% or less, Fe₂O₃0.50% or less, Na₂
O 0.50% or less, ZrO₂ Controlled below 0.50%
MgO-SiO characterized by₂How to make porcelain
Created the law.

The MgO powder and the SiO ₂ powder do not mean naturally occurring raw materials but those purified by removing impurities by appropriate means. Examples of the impurities include Al, Ca, Fe, Na and the like, and MgO powder or SiO ₂ powder in which these impurities are controlled is preferable. Further, the SiO ₂ colloidal solution is preferably a colloidal solution in which the impurities are controlled.

The above-mentioned calcination is carried out in order to reduce the firing shrinkage rate during the sintering of the molded product and to stabilize the characteristics accompanying the homogenization of the components. Calcination is, for example, 1200-1
It is carried out at 400 ° C. for 2 to 4 hours, and MgO phase and SiO ₂ phase are formed in the composition of the calcined powder after calcination, in addition to the forsterite phase or the enstatite phase.

The calcinated powder of each calcined composition can be pulverized by, for example, a ball mill using zirconia balls. The pulverization is mainly performed by setting the average particle size of the calcined powder to an average of 3 μm or less. This is because if the particle size of the MgO-SiO ₂ based porcelain powder is large, the sinterability during sintering is poor and a dense sintered body cannot be obtained. In the pulverizing step, if necessary, a predetermined amount of polyvinyl alcohol, methyl cellulose or the like as a binder is simultaneously mixed and pulverized to obtain a MgO—SiO ₂ based synthetic powder. It should be noted that a compound such as a binder is also of high purity like the raw material powder.

The above-mentioned molded product is molded into a predetermined shape according to the application by an appropriate pressure molding means. The molded product is degreased to remove the organic compound such as the binder. The degreasing temperature is set to a temperature at which the organic compound can be burned and removed, and is, for example, 300 to 500 ° C. and 4 to 7 hours. After degreasing, it is subsequently sintered. The firing is, for example, 1400 to
It is carried out at 1600 ° C. for 2 hours.

In the present invention, from the weighing of the raw material powder,
In each step of mixing, calcination, crushing and firing,
Materials and hands that prevent impurities from mixing into the baked powder, synthetic powder, etc.
Stages are used to ensure full purity throughout the entire process
Be considered. Impurities are Al ₂O₃, CaO, Fe₂O
₃, ZrO₂Mainly.

[0013]

[Function] Dense Mg with low dielectric constant and low dielectric loss
Since it is an O—SiO ₂ system porcelain, high speed signal propagation is possible. In addition, from the SiO ₂ raw material and the MgO raw material, MgO
Mixtures -SiO ₂ system is formed. Such a mixture is calcined, forsterite phase, enstatite phase, Si
The O ₂ phase and the MgO phase are formed, and the calcined powder has a composition in which at least two phases are always mixed among these phases. The calcined and crushed synthetic powder is a high-purity MgO-SiO ₂ -based synthetic powder because impurities are regulated, and a high-purity MgO-SiO ₂ -based porcelain can be obtained. Has become.

Further, by controlling the average particle size of the MgO-SiO ₂ -based synthetic powder to 3 μm or less, the sintering aid can be made unnecessary, and the generation of the glass phase by the sintering aid can be eliminated. It becomes a porcelain that is dense and has excellent electrical characteristics. Further, in the forsterite composition and the composition richer in SiO ₂ than that, it is considered that the sintering temperature is lowered due to the liquid phase formation due to excessive addition of SiO ₂ .

[0015]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3 and Tables 1 to 6. This example is an example of the present invention, and the present invention is not limited to this. Example 1 First, high-purity MgO powder and high-purity SiO ₂ powder are prepared as raw materials. In this example, the MgO powder has an average particle diameter of 0.08 to 0.10 μm and a specific surface area of 26.0.
Using SiO ₂ powder of 3 m ² / g, 0.8
The one having a specific surface area of 2 μm and the specific surface area of 1.78 m ² / g was used. The particle size of the raw material powder used may be such that it reacts sufficiently during calcination. MgO powder and S used in this example
The results of analysis of the purity of the iO ₂ powder are shown in Table 1. In Table 1, the numerical unit of each component is% by weight, and the-mark indicates 0.001% or less.

[0016]

[Table 1]

Next, according to FIG. 1, the MgO-S of this example is used.
A process of manufacturing an iO ₂ -based porcelain will be described. MgO and Si
The molar ratio of O ₂ is 2.5: 1, 2.3: 1, 2.1: 1,
2: 1 (forsterite composition) 2: 1.1, 2:
1.3, 2: 1.5, 2: 1.7, 2: 1.8, 2:
1.9, 2: 2 (enstatite composition) (11 types in total)
To obtain the high-purity MgO powder and high-purity SiO ₂
The powder was weighed, distilled water was added, and the mixture was mixed in a ball mill for 24 hours using urethane balls to obtain uniform mixtures a to k. For each of the mixtures a to k, after drying under predetermined conditions, I: 1200 ° C., II: 1300 ° C. and III, respectively.
Calcination powders Ia to Ik, IIa to IIk and III are calcined at three temperatures of 1400 ° C. for 3 hours each.
a to IIIk were obtained. For these calcined powders Ia to IIIk,
Table 2 shows the results of confirming the MgO-SiO ₂ composition by X-ray diffraction.

[0018]

[Table 2] P1: Main peak P2: Clearly present peak (10% or more of main peak) P3: Slightly present peak F: Forsterite E: Enstatite M: MgOS: SiO ₂ ↓ ↑: Shows that the peak increases in the direction of the arrow

As is clear from Table 2, each calcined powder Ia-
The composition of MgO-SiO ₂ of III k had mainly of forsterite phase for any of the calcined powder other than the calcined powder Ig~Ik and III g~III k is a SiO ₂ rich calcination powder. In addition, in any of the calcined powders Ia to IIIk,
From forsterite composition to MgO richer Mg
There was a tendency that the more O ₂ phase and the more SiO ₂ rich, the more SiO ₂ phase or enstatite phase. further,
A single phase of forsterite was not formed even with the calcined powders Id to IIId having the forsterite composition.

As described above, the calcined powders Ia to IIIk which are not forsterite single phase are pulverized by a ball mill so that the average particle diameter becomes 3 μm or less, and 1% by weight of polyvinyl alcohol as a binder is further added. ground mixture was a total of 24 hours grinding treatment to obtain a MgO-SiO ₂ based synthetic powder Ia~III k. Synthetic powders Ia to III k
The average particle diameter and particle size distribution of the powder after pulverization were measured using a laser diffraction scattering method. The average particle size is shown in Table 3. The measured average particle size is 1 μm except III d.
It was m or less. As an example of particle size distribution, synthetic powder IId
The particle size distribution of is shown in FIG. In this figure, the vertical scale on the right shows the scale of the bar graph, and the vertical scale on the left shows the scale of the line graph.

[0021]

[Table 3]

The MgO--SiO ₂ synthetic powders Ia to I
k was formed into a cylindrical shape having a diameter of 20 mm and a thickness of 8 to 9 mm. The molding was first carried out by uniaxial molding (temporary molding) of 500 kg / cm ² and then CI at 3000 kg / cm ² .
P-molding (main molding) into molded products Each molded product was placed in a heating furnace, heated from room temperature to 400 ° C for 6 hours, heated at 400 ° C for 6 hours to degrease, and then 200 ° C.
The temperature was raised at a heating rate of / hour, and firing was performed for 2 hours at a firing temperature at which the molded product became dense. The densification referred to here means when the water absorption of the fired product is 0.1% or less and the porosity is 1% or less. Table 4 and FIG. 3 show the densification temperature of each sintered body, the relative permittivity and the dielectric loss tangent measured by a dielectric cylinder resonator method with both ends short-circuited. For electrical measurement, the fired product was processed into a cylindrical shape having a diameter of 10 mm and a thickness of 5 mm, and the measurement frequency was measured at around 16 GHz. Also,
Table 5 shows the relative permittivity and dielectric loss tangent of the conventional forsterite porcelains a to c. Here, the conventional forsterite porcelain is a commercial product which is not of high purity and whose average particle size is not taken into consideration. In addition, the measured values in Table 5 are obtained by using commercially available fortelite porcelain of several companies with a diameter of 10 m.
It was processed into a cylindrical shape having a thickness of 5 mm and a thickness of 5 mm, and was measured at a frequency around 16 GHz by the same measurement method as that for the sintered body.

[0023]

[Table 4]

[0024]

[Table 5]

From Table 4 and FIG. 3, the sintered bodies using the synthetic powders Ia to Ih can be densified in the range of 1450 ° C to 1600 ° C. That is, a dense sintered body is obtained in a wide temperature range of 150 ° C. In particular, the sintered bodies of synthetic powders Ia to Ih can be densified at 1450 ° C. In addition, a dense sintered body could not be obtained for any of the synthetic powders Ii to Ik. This is probably due to decomposition and melting of these synthetic powders.

In the sintered bodies derived from the synthetic powders Ia to Ih, the sintered bodies of the synthetic powders Ia to IIc are as follows:
Having a dielectric loss tangent of 6 to 7 × 10 ⁻⁵ and synthetic powder Id to
The sintered body of Ih has a dielectric loss tangent of 7 to 8 × 10 ⁻⁵ , and each has a low dielectric loss tangent of 1 × 10 ⁻⁴ or less. This is on the order of 1 order of magnitude less than the dielectric loss tangent of the conventional forsterite porcelain (see Table 5).

Furthermore, the sintered body derived from the synthetic powder Ia~Ih, relative dielectric constant 6.8 of the sintered body of the composite powder Id forsterite composition, synthesis of SiO ₂ rich composition powder Ie~ For the Ih sintered body, 6.9 to 6.7.
And a relative dielectric constant of MgO-rich synthetic powders Ia to I
In the sintered body of c, the relative dielectric constant of 7.3 to 7.0 is obtained.

That is, in the sintered body of the synthetic powders Ia to Ig, the molded product can be densified in the firing temperature range of 1450 ° C. to 1600 ° C., and the dielectric loss tangent can be obtained by any of the sintered bodies. Can be regulated to 1 × 10 ⁻⁴ or less. In particular, in the sintered body of synthetic powders Id to Ih,
Densification was performed at a firing temperature near 1450 ° C. and a relative dielectric constant of 6.
The dielectric loss tangent can be set to ⁵ to 7.0 and the dielectric loss tangent to 7 to 8 × 10 ⁻⁵ . Further, in the sintered body of the synthetic powders Ia to Ic, if it is sintered at 1600 ° C. to be densified, the dielectric loss tangent is 6 to 7 × 10 ⁻⁵ and the relative dielectric constant is up to about 7.5. It can be raised.

Other synthetic powders IIa-IIh, IIIa-
With respect to IIIh, the same results as those of the densification temperature, relative permittivity and dielectric loss tangent tendencies observed in firing of Ia to Ig are obtained. Electron micrographs of the surfaces of the sintered bodies of the synthetic powders Ia to Ig are shown in FIGS. 4 to 6, respectively. 4 to 6
As is apparent from the above, any of the synthetic powders is a dense sintered body. Further, as the forsterite composition becomes MgO rich or SiO ₂ rich, the grain growth of the sintered body is suppressed.

Further, from the result of X-ray diffraction of the obtained sintered body, the molar ratio of MgO and SiO ₂ was 2: 1.1 to 2: 2.
In the sintered body having a composition ratio of 1.7, only two phases, a forsterite phase and an enstatite phase, are observed.
The amount of enstatite phase increased as the O ₂ richer. That is, since enstatite is difficult to sinter and has conventionally formed a glass phase to prevent dense sintering and deterioration due to transition, in the present example, high purity and no formation of a glass phase were performed. And a dense sintered body could be obtained.

Table 6 shows the results of chemical analysis of the content of impurities in the sintered body of this example. In this embodiment, since the raw material in which the impurities are controlled is used and the mixing of the impurities is controlled also in the process, the amount of impurities in the sintered body is almost determined by the amount of impurities contained in the raw materials used. And almost the same result is obtained as shown in Table 6. However, since ZrO ₂ balls are used in the calcination powder crushing process, zirconia (Zr
Regarding O ₂ ), the amount of contamination due to abrasion during pulverization is included.

[0032]

[Table 6]

Example 2 Next, S was used as a SiO ₂ raw material.
MgO using SiO ₂ colloidal solution instead of iO ₂ powder
A method of manufacturing —SiO ₂ porcelain will be described. Mg
As the O powder, the same one as in Example 1 was used, and SiO
_{2 As a} colloidal solution, the solvent is water and the SiO ₂ content is
20-21% by weight, particle size 10-20 nm, pH 2-4
I used the one. Table 7 shows the purity test results of this SiO ₂ colloid solution.

[0034]

[Table 7]

The MgO powder and the SiO ₂ colloidal solution were mixed with M
Mixtures p and q were weighed and mixed so that the molar ratio of gO and SiO ₂ was 2.5: 1 and 2: 1.7, respectively, and the same steps as in Example 1 were followed at 1200 ° C. and 1300. Calcined at ℃, calcined powder Ip and Iq, IIp and
IIq was obtained. The X-ray diffraction results of these calcined powders corresponded to calcined powders of similar composition in Example 1. Also shows the average particle diameter of MgO-SiO ₂ synthesized powder obtained by pulverizing these calcined powders in Table 8. All have an average particle size of 1μ
It was m or less.

[0036]

[Table 8]

Further, the calcined powders Ip and Iq were molded in the same manner as in Example 1 and baked for 2 hours at the baking temperature at which the molded product was densified under the same temperature rising conditions. The densification temperature of each sintered body and processing into a cylindrical shape having a diameter of 10 mm and a thickness of 5 mm were carried out, and Example 1
Table 9 shows the relative permittivity and dielectric loss tangent in the vicinity of 16 GHz by the same measurement method as in.

[0038]

[Table 9]

As is clear from Table 9, in the sintered body derived from the SiO ₂ -rich synthetic powder Iq, a porcelain having a low relative dielectric constant can be obtained at a low sintering temperature, and the MgO-rich synthetic powder Ip can be obtained. In the sintered body derived from, it was possible to obtain a porcelain having a small dielectric loss tangent. That is, even when the SiO ₂ colloidal solution is used as the SiO ₂ raw material,
The molar ratio of MgO to SiO ₂ is 2.5: 1 to 2: 1.7.
Of Mg having excellent electrical properties almost in the same range as in Example 1
O-SiO ₂ porcelain can be obtained, and the relative dielectric constant is 7.1 to
It was confirmed that it could be changed within the range of 6.4.

As in Example 1, the results of chemical analysis for the content of impurities in the sintered body composed of the MgO powder and the SiO ₂ colloidal solution are shown in Table 10.

[0041]

[Table 10]

[0042]

As described in detail above, the MgO-
According to the SiO ₂ porcelain, M with highly controlled impurities
Since it is a gO-SiO ₂ porcelain, it has a low dielectric loss and a low dielectric constant, and is a material suitable for a high-frequency insulator substrate such as an excellent circuit substrate that enables high-speed propagation of signals. According to the method for producing a MgO-SiO ₂ porcelain of the present invention, MgO powder, SiO ₂ powder or SiO ₂ colloidal solution is used as a raw material, and the mixing of impurities is controlled in the process to obtain a molar ratio of MgO and SiO ₂ . Are mixed in the range of 2.5: 1 to 2: 1.7, and calcined to obtain a synthetic powder having a controlled average particle size, which does not decrease the sinterability and is almost equal to that of conventional forsterite. It is possible to obtain a dense porcelain having electrical properties with a loss of one digit or more (dielectric loss tangent is 1 × 10 ⁻⁴ or less). Further, the MgO-SiO ₂ based ceramic composition within the above range, the dielectric constant while maintaining the dielectric dissipation factor (low loss property 1 × 10 ^-4 or less) 6.4
It can be adjusted in the range of 7.5.

[Brief description of drawings]

FIG. 1 is a process drawing for obtaining a MgO—SiO ₂ based porcelain of the present invention.

FIG. 2 is a particle size distribution diagram of MgO—SiO ₂ based synthetic powder.

FIG. 3 is a diagram showing a densification temperature, a relative dielectric constant and a dielectric loss tangent of a sintered body, respectively.

FIG. 4 is a view of electron microscope photographs (a) to (c) of surfaces of sintered bodies of synthetic powders Ia to Ic.

FIG. 5 is an electron micrograph (d) of the surface of a sintered body of synthetic powder Id.

FIG. 6 is a view of electron microscope photographs (e) to (g) of surfaces of sintered bodies of synthetic powders Ie to Ig.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takehisa Fukui 3 from 6-28, Kyowa-cho, Obu City, Aichi Prefecture (72) Inventor Yutaka Higashida 3 from 2--18, Mitsugaoka, Komaki City, Aichi Prefecture (72) Inventor Kaku Tsutomu Oka 25 No. 8 Dandome, Kariya city, Aichi prefecture 8

Claims (4)

[Claims] 1. A dense hybrid sintered body having a forsterite phase and / or an enstatite phase, wherein the molar ratio of MgO and SiO ₂ is in the range of 2.5: 1 to 2: 1.7 and the relative dielectric constant. Index 6.4 to 7.5, dielectric loss tangent 1 × 1
0 ^-4 in MgO-SiO ₂ based ceramic, characterized in that. 2. The impurity according to claim 1, wherein the impurities contained in the hybrid sintered body are Al ₂ O ₃ 0.50% or less and CaO.
0.50% or less, Fe ₂ O ₃ 0.50% or less, Na ₂ O
0.50% or less, ZrO ₂ 0.50% or less, MgO-SiO ₂ based porcelain. 3. (1) MgO powder and SiO₂Powder or Si
O₂The colloidal solution is MgO and SiO₂Has a molar ratio of 2.
A step of mixing and firing only in the range of 5: 1 to 2: 1.7, and (2) the calcined powder obtained in the above step to have an average particle size of 3 μm or less.
Crush and MgO-SiO ₂(3) This MgO-SiO₂Pressure-forming synthetic powder
Forsterite and / or en
MgO-SiO with statite composition₂Process to make system porcelain,
MgO-SiO characterized by comprising₂Porcelain
Production method. 4. The impurity contained in the MgO—SiO ₂ porcelain according to claim 3, wherein Al ₂ O _{3 is} 0.50% or less, C
aO 0.50% or less, Fe ₂ O ₃ 0.50% or less,
A method for producing a MgO—SiO ₂ porcelain, characterized by controlling Na ₂ O to 0.50% or less and ZrO _{2 to} 0.50% or less.