JPH01317154A - Production of calcined substance for producing inorganic dielectric powder - Google Patents

Abstract

PURPOSE:To obtain a calcined substance capable of preparing low-cost inorganic dielectric powder in a short production time by using powder prepared by presubjecting the surface thereof to specific treatment as raw material powder in calcining the raw material powder and obtaining the calcined substance used for producing inorganic dielectric powder. CONSTITUTION:Raw material powder is calcined to provide a calcined substance for producing inorganic dielectric power. In the process, powder prepared by preapplying a substance 2 for providing a liquid phase in calcining and a substance 3 for weakening bond of mutual powder in calcining to the surface of powder 1 is used. The substance 2 for providing the liquid phase in calcining is preferably applied and then the substance 3 for weakening the bond of the mutual powder in calcining is preferably applied. In order to apply the above- mentioned substance 2, for example, an aqueous solution of Bi(NO3)3.5H2O is kneaded with fine ZrO2 powder so as to provide a composition of Bi2(ZrO3) to afford a slurry, which is then applied to the raw material powder, dried and pulverized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a fired product for producing inorganic dielectric powder.

[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 new media, devices are becoming more compact, and along with this, miniaturization of microwave three-dimensional circuit elements such as dielectric resonators is strongly desired.

The size of the microwave three-dimensional 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. /εrOS. 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.

A ceramic substrate is often used as the dielectric substrate. The most popular ceramic substrate is Al2.
It is a zOi substrate. Although the dielectric constant is somewhat small (9, 8), it is larger than that of a normal resin substrate.

However, with ceramic substrates, post-processing (drilling and cutting) is not easy, heat dissipation plates cannot be easily crimped, and it is difficult to make large areas, so when making circuit boards, the number of so-called multi-chip circuit boards is small and productivity is low. There is a drawback that it is low.

In order to solve these problems, a high dielectric constant (εr=50
Composite substrates using inorganic dielectric powders and resins having a particle size of 0 to 8,000) are being developed. This composite substrate is required to have a moderately large dielectric constant εr (about εr-10 to 30). If the dielectric constant is too large, the required width of the circuit becomes too narrow, making it difficult to form the circuit. By mixing inorganic dielectric powder with a high relative permittivity with a resin, a suitably large relative permittivity εr is achieved.

[Problem to be solved by the invention]

However, a composite substrate using an inorganic dielectric powder and a resin has large changes in relative permittivity with respect to temperature and changes in relative permittivity and dielectric loss with respect to frequency, and is not sufficiently stable.

Moreover, the inorganic dielectric powder used for composite substrates has disadvantages in that it takes a long time to manufacture and is expensive. It takes a long time to grind the fired product.

In view of these circumstances, it is an object of the present invention to provide a method for producing a fired product that can produce inorganic dielectric powder in a short manufacturing time and at low cost. [Means for Solving the Problems] The above-mentioned problems In order to solve the problem, in the invention according to claim 1.2, when a raw material powder is fired to obtain a fired product used for producing an inorganic dielectric powder, the raw material powder becomes a liquid phase during the firing. A powder is used in which a substance that weakens the bond between the substance and the powder during firing is attached to the surface of the powder in advance, and in the invention as claimed in claim 2, a substance that becomes a liquid phase during firing is attached to the surface of the powder. A substance is attached to the powder that weakens the bond between the powders during firing.

[For production]

In the fired product obtained by the invention described in claim 1.2, the substance that was in a liquid phase during firing wraps the powder and applies compressive stress. When compressive stress is applied to the crystal grains in the powder, the dielectric's relative permittivity versus temperature characteristics and relative permittivity and dielectric loss versus frequency characteristics become better.

During firing at the required temperature, the powders are sintered and bonded together, but because there is a substance attached to the surface of the raw powder that weakens the bond between the powders, the degree of sintering, that is, the degree of bonding, is weak. . Therefore, the fired product is easily crushed, and the time required for crushing the fired product is short.

According to the invention as claimed in claim 2, when the substance is attached so that the substance that becomes a liquid phase during firing is on the inside and the substance that weakens the bond between powders during firing is on the outside, The substance that becomes the liquid phase comes into direct contact with the surface of the raw powder, effectively enveloping the powder, while the powders only come into contact with each other through a substance that weakens the bond between them, so it effectively wraps the powder during firing. Bonds can be weakened.

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples thereof.

Calcined powder is usually used as the raw material powder. The dielectric powder is calcined in advance to form a dielectric powder with a certain composition.

For example, B a o , y s S r o , z
A calcined powder having a composition of s T iOx is used. BaC0□,
A predetermined amount of each powder of 5rCO□ and TiO□ was blended, mixed well, and placed in an alumina crucible under an air atmosphere.
A calcined product is obtained at a temperature of 1100"C. This is crushed into a calcined powder by wet pulverization using a nylon pot and nylon coated steel balls. This calcined powder has a particle size of, for example, 0.5 to 5. The particle size is in the range of about 0 μm.
Depending on the composition of the calcined powder, MgTi01. , CaTi0t, Ba5iO+ , F
ew Ox, etc. may be used in combination. However, when crushed, the depresosa effect weakens.

Next, the surface of the calcined powder 1 is subjected to a treatment in which a substance 2 that becomes a liquid phase during firing is attached to the surface.

This process is performed as follows, for example. B12 (Zr
B i (No-)! so that the composition is O+).・
Zr021g in an aqueous solution of 5H20! Particles (Resident Semen +
-H fine particles Zr○: 0.007-0.01
pm) to obtain a slurry, and use a Raikai machine to
While adding this slurry-like material little by little, the previously calcined powder is stirred to adhere the slurry-like material. And -
Then, dry and crush.

Next, as shown in FIG. 1, a substance 3 that weakens the bond between the powders during firing is further attached to obtain a raw material powder.

Next, the raw material powder thus created is fired (main firing) to produce a fired product. As shown in FIG. 2, the substance 2 which becomes a liquid phase upon firing becomes a layer 2' surrounding the original calcined powder. In the obtained fired product,
Since the thermal expansion coefficient of N2' is smaller than that of the wrapped inner part 1', compressive stress (mechanical strain) is applied to the crystal grains. In other words, the substance that becomes a liquid phase during firing and the substance that weakens the bond between powders during firing have a coefficient of thermal expansion smaller than that of the inner part 1' when it becomes the phase 2' that surrounds the inner part 1'. It is a substance.

As shown in FIG. 2, the substance 3 that weakens the bond between the powders during firing remains on the outermost surface in the form of a residue 3' and weakens the bond between the particles.

In the case of main firing, the firing temperature is usually 1200 to 1400.
°C range. This is to cause the constituent crystals to grow to a certain extent so as to have predetermined dielectric properties.

When firing in the above temperature range, the powder of the fired product is usually strongly sintered, but in the fired product of the present invention, the sintering is weakened by substances adhering to the surface.

The fired product is pulverized by, for example, wet pulverization using a nylon pot and a nylon-coated steel ball.

The powder particle size (average particle size) of this inorganic dielectric powder (ceramic dielectric powder) is usually 0.1 to 3
The particle size is preferably about .mu.m (having a particle size distribution of about 0.1 to 10 .mu.m).

To make a composite board, a resin composition (which may contain a crosslinking agent, etc.) and an inorganic dielectric powder are mixed, and if necessary, a thin metal such as copper is laminated, and then heated and pressure molded. do.

In order to increase the strength of the composite substrate, a base material such as glass cloth is impregnated with a mixture of resin and powder, and if necessary, a thin metal layer is laminated and molded under heat and pressure. for example,
A glass cloth with a thickness of 100 μm is impregnated with a mixture of 30 parts by volume of an inorganic dielectric powder and 70 parts by volume of a resin liquid containing PPO' (polyphenylene oxide) resin and styrene as a polymeric crosslinking agent, and then dried. Five dried base materials and 35 μm thin copper were laminated on both sides and heated at 200°.
The copper-clad composite substrate (thickness: 0.81i+) is completed by heating and pressurizing and curing at a temperature of C. Of course, the copper thin film is used for forming a circuit, and the circuit is formed by a normal etching method or the like.

Next, more specific examples and comparative examples from obtaining a fired product according to the present invention and from powdering to obtaining a composite substrate will be explained.

Example 1 - First, calcined powder (dielectric powder) was created as follows.

B ao, vs S r o, 2 G T
! As a starting material, B a
A well-mixed mixture of Cow, Sr Cow, and TiO2 powders was calcined in an alumina crucible in an air atmosphere at a temperature of 1100°C to obtain a calcined product. This pre-calcined product was powdered by wet pulverization using a nylon pot and nylon coated steel balls, and the 0.
A calcined powder of 5 to 5 μm was prepared.

On the other hand, Zr0z fine particles (fine particles Zr01 manufactured by Sumitomo Cement ■) were added to an aqueous solution of B i (NO=), ・5H,O so that the composition became B i , (Z r O,).
:Q, 007 to 0.01 μm) to obtain a slurry. This slurry had a solids content of 3%. Using a Raikai machine, this slurry was added little by little while stirring and mixing the previously calcined powder. This mixture was dried at 100° C. and then ground using a Laikai machine. A slurry-like substance that adheres to the surface of the calcined powder is a substance that becomes a liquid phase during firing.

The substance that becomes a liquid phase during firing in this invention is not necessarily the same before and after firing. In this example, before firing, a mixture of B i (NO2)- and Zr0z has a composition of Biz(Zr○, )8 after firing. Of course, it goes without saying that a substance whose composition does not change before and after firing may be used.

Next, take this powder and apply it to Zr alkoxide coating material (High Purity Chemical @ Zr Coating Material)
The 8% solution was diluted to a 1% solution with isopropyl alcohol and poured to thoroughly wet the powder. Thereafter, excess coating liquid was separated and removed by filtration. The powder was dried to obtain a raw material powder. The Zr coating material attached to the powder surface is a substance that weakens the bond between the powders during firing.

The substance that weakens the bond between powders during firing in this invention is not necessarily the same before and after firing. In this example, the composition is Zr alkoxide before firing, but becomes ZrO2 after firing. Of course, it goes without saying that a substance whose composition does not change before and after firing may be used. This material (or the changed material if the composition changes due to firing) remains on the surface without completely dissolving (reacting) in the liquid phase below. In this example, for example, when performing X-ray analysis,
A peak of ZrO□ appears.

7. This raw material powder. r 1350° in Ot crucible
A fired product was obtained by main firing for C12 hours. This fired product was ground in a pot mill to obtain an inorganic dielectric powder. The particle size of this powder was approximately 2 μm, and the time required for pulverization was 17.5 hours.

A mixture of 25 parts by volume of the powder obtained in this manner and 75 parts by volume of PPO resin was prepared, placed in a mold so that a thin copper layer of 35 μm in thickness was laminated on both sides, and heated to 230°C.
A composite substrate was obtained by pressure molding at a temperature of 100 mL and cooling to room temperature while applying pressure.

Example 2 - A composite substrate was obtained in the same manner as in Example 1, except that the fired product was created as follows.

B 12 (Z r Ox ) Instead of x, B 12 (
T i O.

), fine particles of Tie and Bi(N
A slurry with O=)-.5H60 was used.

Example 3 - A composite substrate was obtained in the same manner as in Example 1, except that the fired product was created as follows.

B 12 (S n
OH), fine particles of 3nOt and B
A slurry with i(NO8)*.5H20 was used.

Example 4 - 47 fluoride ethylene (fluororesin) instead of PPO resin
A composite substrate was obtained in the same manner as in Example 1, except that the 25 μm powder was used and direct pressure molding was performed at 350° C.

Example 5 - A composite substrate was obtained in the same manner as in Example 2, except that 25 μm powder of tetrafluoroethylene was used instead of the PPO resin and direct pressure molding was performed at 350°C.

Example 6 - A composite substrate was obtained in the same manner as in Example 3, except that 25 μm powder of 47 fluoroethylene was used instead of the PPO resin and direct pressure molding was performed at 350°C.

- Comparative Example 1 - In Example 1, 7. 1350℃ in rot crucible, 2
A composite substrate was obtained in the same manner as in Example 1, except that the baking was performed for a certain time. The time required for pulverizing the fired product was approximately 37 hours.

-Comparative Example 2- A composite substrate was obtained in the same manner as in Comparative Example 1, except that 25 μm powder of tetrafluoroethylene was used instead of the PPO resin and direct pressure molding was performed at 350°C.

Regarding the composite substrates of Examples 1 to 6 and Comparative Example 1.2,
Change rate of relative permittivity εr at -20 to 80℃ (IMHz)
was measured. Relative permittivity εr at IMHz and IGHz
and dielectric loss tan δ were also measured. The measurement results are shown in Table 1.

1E In Examples 1 to 6, the pulverization time of the fired product was 17.5 hours, which was only half of the pulverization time of Comparative Example 1, which was 37 hours.

It can be seen that the grinding time is significantly shortened. As shown in Table 1, in the example, the temperature change in relative permittivity was approximately 3
~6%, which is extremely small compared to 20% in the comparative example.

There is also little change in relative permittivity and dielectric loss with respect to frequency. In the composite substrate, the compressive stress applied to the inorganic dielectric powder by the resin also contributes to improving the relative permittivity and dielectric loss vs. frequency characteristics.

This invention is not limited to the above embodiments. It goes without saying that the powder composition may have a composition other than those exemplified above. 7. As a substance that weakens the bond between powders during firing. rO
The z powder may be applied from the beginning.

A vibration mill or a jet mill may be used to grind the fired product.

The resin of the composite substrate may be unsaturated polyester resin, epoxy resin, or the like. However, composite substrates using unsaturated polyester resin tend to have large dielectric loss.

〔Effect of the invention〕

As described above, in the method for producing a fired product for producing inorganic dielectric powder according to the invention described in claim 1.2, since the bond between the powders in the fired product is weak, the time required for pulverizing the fired product is shortened, and the powder production Shorter time and lower costs.

In addition, the crystal grains of the powder are subjected to compressive stress and have paraelectric properties, and in the dielectric powder obtained by pulverizing the fired product, the relative permittivity vs. temperature characteristics and the relative permittivity vs. dielectric loss vs. Frequency characteristics are improved.

According to the manufacturing method of the invention described in claim 2, the characteristics can be improved more effectively and the bond between the powders can be weakened.

[Brief explanation of the drawing]

1 and 2 are schematic cross-sectional views of the raw material powder used in the manufacturing method of the present invention, with FIG. 1 showing the powder before firing and FIG. 2 after firing, respectively. 1...Calculated powder 2...Substance that becomes a liquid phase during firing 3...Substance that weakens the bond between powders during firing 1 Figure 2 Figure 2 Ding Fufu Seisho (self-published) Showa August 5, 1983 Patent Application No. 148712 2 Title of the invention Method for manufacturing fired product for manufacturing inorganic dielectric powder 3 Relationship with the case of the person making the amendment Patent applicant address Oaza Kadoma, Kadoma City, Osaka Prefecture 1048 Address Name (583) Matsushita Electric Works Co., Ltd. Representative Toshio Miyoshi 4, No agent 6, Subject of amendment 6, Specification subject to amendment 7, Contents of amendment■ Specification page 7 In line 18, the word "small" should be corrected to "large." ■ In the third line of page 8 of the specification, the word "small" should be corrected to "large."

Claims (1)

[Scope of Claims] 1. When firing a raw material powder to obtain a fired product for producing an inorganic dielectric powder, the raw material powder includes a substance that becomes a liquid phase during the firing and a bond between the powders during the firing. 1. A method for producing a fired product for producing an inorganic dielectric powder, characterized in that the powder has a surface preliminarily attached with a substance that weakens the dielectric properties. 2. The method for producing a fired product for producing an inorganic dielectric powder according to claim 1, wherein a substance that weakens the bond between the powders during firing is attached on top of the deposited substance that becomes a liquid phase during firing.