JPH01298053A - Production of sintered material for producing inorganic dielectric powder - Google Patents

Abstract

PURPOSE:To obtain the title sintered material capable of producing inorg. dielectric powder in a short time at a low cost by previously depositing a substance capable of weakening the binding strength between powder particles in calcination on the surface of raw powder, and then sintering the raw powder. CONSTITUTION:The calcined powder of Ba0.9Sr0.1TiO2, etc., is ordinarily used as the raw powder to obtain a sintered material. Namely, the calcined material is wet-crushed by the wet crushing using a nylon pot And nylon-coated steel balls to obtain the calcined powder. The particle diameter of the calcined powder is controlled, for example, to about 0.5-5.0mum. A substance capable of weakening the binding strength between the powder particles such as fine ZrO2 powder is then deposited on the surface of the calcined powder. The obtained raw powder is sintered at 1200-1400 deg.C to obtain the sintered material for producing inorg. dielectric powder. In addition, the sintered material is crushed, for example, by the wet crushing using a nylon pot and nylon-coated steel balls.

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 being made more compact, and along with this, there is a strong desire for miniaturization of microwave three-dimensional circuit elements such as dielectric resonators.

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 a relative permittivity εr is λ=
λ. /εrllS. 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 A1t.
o*Substrate. Although the relative dielectric constant is somewhat small (9, 8),
Larger than normal resin substrates.

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, inorganic dielectric powder used in composite substrates has drawbacks such as long manufacturing time and high cost. It takes a long time to grind the fired product.

SUMMARY OF THE INVENTION In view of the above 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 production time and at low cost.

[Means to solve the problem]

In this invention, in order to solve the above problem, when firing raw material powder to obtain a fired product for producing inorganic dielectric powder, a substance that weakens the bond between the powders during firing is preliminarily applied to the surface of the raw material powder. The attached powder is used.

[For production]

During firing at the required temperature, the powders are sintered and bonded together, but since 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 (beat). Therefore, the fired product is easily crushed, and the time required for crushing the fired product is short.

〔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, a calcined powder having a composition of B a *, * S ro, + T i Ox is used. B a COs , S r CO
! A pre-calcined product is obtained by blending a predetermined amount of each powder of TiO□ and TiO□ in an aluminum crucible at a temperature of 1100°C. This calcined powder has a particle size in the range of, for example, 0.5 to 5.0 μm. Depending on the composition of the calcined powder,
As so-called depressors, MgTi0*, CaTi
0*, BaS ios, Fegoz, etc. may be used in combination. However, when crushed, the depressor effect tends to weaken.

Next, a raw material powder is prepared by attaching a substance to the surface of this calcined powder to weaken the bond between the powders during firing. This substance may be attached to the surface of the calcined powder 1 in the form of particles 2, as shown in FIG. 1, or may be attached in the form of layers 3, as shown in FIG. Specifically, ZrO
□ Perform processing such as attaching fine powder.

Next, the raw material powder thus created is fired (main firing) to produce a fired product.

In the case of main firing, the firing temperature is usually 1200 to 1400.
℃ 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 thereon, followed by heat-pressing molding. for example,
A mixture of 70 parts by volume of a resin solution containing PP0 (polyphenylene oxide) resin and styrene as a polymeric crosslinking agent and 30 parts by volume of geometric dielectric powder was impregnated into a 100 μm thick glass cloth and dried. 5 dried base materials and 35 μm thin copper were laminated on both sides and heated at 200°C.
The copper-clad composite substrate (thickness: 0.8 mm) is completed by curing by heating and pressurizing at a temperature of . Of course, thin copper is not suitable for forming circuits, and circuits are formed by ordinary etching methods.

By the way, in a composite substrate, the relative dielectric constant changes greatly with respect to temperature, and stability is not sufficient. However, when the raw material powder to be subjected to main firing is a mixture of a plurality of types of calcined powders having different Curie temperatures, the change with respect to temperature can be reduced. The finally obtained inorganic dielectric powder is a powder in which portions with different Curie temperatures are connected in parallel and series, thereby significantly improving the temperature characteristics of the relative dielectric constant of the composite substrate.

Of course, even if inorganic dielectric powders with different Curie temperatures are packed separately and mixed together at the stage of mixing with the resin, the change in relative dielectric constant with respect to temperature can be reduced. but,
Temperature characteristics can be improved to a greater degree by mixing powders with different Curie temperatures at the stage of calcining powder before main firing.

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 Three types of calcined powders (dielectric powders) were created as follows.

A well-mixed mixture of B a COx , S r COx , and TiO powders was calcined at a temperature of 1100°C in an aluminum crucible so that it had a composition of Bao, *es re, +oTiOz. A pre-fired product was obtained. This pre-calcined product was powdered by wet pulverization using a nylon pot and nylon coated steel balls, and the 0.
A calcined powder (calcined powder A) having a diameter of 5 to 5 μm was prepared.

As above, B a T io, *s Z r e,
A mixture of BaC0*, Zr0g, and TiO3 powders was blended and mixed well so as to have a +sos composition.
A calcined product was obtained by calcining in an aluminum crucible at a temperature of 1100°C. This calcined product was pulverized by wet pulverization using a nylon pot and a nylon-coated steel ball to create a calcined powder (calcined powder B) of 0.5 to 5 μm.

Again, similarly, B ao, t S re,! Ti
B a COs , S r
A mixture of Cot and TiO□ powders and well mixed was calcined in an alumina crucible at a temperature of 1100° C. to obtain a calcined product. This calcined product was pulverized by wet pulverization using a nylon pot and a nylon-coated steel ball to create a calcined powder (calcined powder C) of 0.5 to 5 μm.

Each of the calcined powders A, B, and C is molded and sintered (1350°
C) When the dielectric properties were investigated, the Curie temperature of calcined powder A was 80°C, the Curie temperature of calcined powder SONG B was 50°C, and the Curie temperature of calcined powder C was 20°C.

On the other hand, Zrog fine particles (manufactured by Sumitomo Cement @ particle size 0.007~0.01 μm) were mixed in distilled water (solid content 3%).
) and prepared a slurry.

Weigh equal moles of each of the calcined powders A, B, and C, and stir the slurry containing the ZrO□ fine particles little by little using a Likai machine. A raw material powder was created by attaching a weakening substance) to the surface of the calcined powder.

The amount of the slurry dropped was such that the amount of ZrO fine powder deposited after drying was 0.1 part by weight per 100 parts by weight of the calcined powder.

After drying this raw material powder at 100°C, it was once pulverized using a Raikai machine, and then pulverized at 1350°C in a ZrOz crucible.
Main firing was performed for 3 hours, and a fired product was obtained by cooling. This fired product was ground in a bollard mill to obtain an inorganic dielectric powder.

The particle size of this powder was approximately 2 μm, and the time required for pulverization was 16.5 hours.

A mixture of 25 parts by volume of the powder thus obtained and 75 parts by volume of PPO resin was made, set in a mold so that a 35 μm thick copper thin layer 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.

The procedure was the same as in Example 1 except that the ratios were 0.5 mol of calcined powder A, 0.3 mol of calcined powder B, and 5042 mol of calcined powder C.

Example 3 - A composite substrate was obtained in the same manner as in Example 2, except that the fired product was created as follows.

7. Instead of the rot slurry, prepare an 8% solution of Zr alkoxide coating material (Zr coating material made by Kojundo Kagaku (manufactured by 41) diluted with isopropyl alcohol to a 1% solution, and calcined it in a beer force. Powder A, B
, C to sufficiently wet the powder, and then filtered to remove and separate the excess coating liquid. In other words, a raw material powder was created in which the surface of the calcined powder was coated with a Zr coating material (a substance that weakens the bond between powders during firing).

Example 4 Each of the calcined powders A, B, and C obtained in Example 1 was
Zr0z fine powder adhesion treatment using r0z slurry 3
Various types of raw material powders were created. ZrO! The fine powder adhesion treatment was the same as in the first example.

Next, fired products of each of the three types of raw material powders were obtained in the same manner as in Example 1, and individually pulverized to create three types of inorganic dielectric powders having different Curie temperatures.

Using a mixed powder obtained by mixing equimolar amounts of each of the obtained powders,
A composite substrate was obtained in the same manner as in the first example.

Example 5 - Tetrafluoroethylene (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 6 - A composite substrate was obtained in the same manner as in Example 2, except that 25 μm powder of tetrafluoroethylene (fluorine resin) was used instead of PPO resin and direct pressure molding was performed at 350°C.

Example 7 A composite substrate was obtained in the same manner as in Example 3, except that 25 μm powder of tetrafluoroethylene (fluorine resin) was used instead of PPO resin and direct pressure molding was performed at 350°C.

Example 8 - A composite substrate was obtained in the same manner as in Example 4, except that 25 μm powder of tetrafluoroethylene (fluorine resin) was used instead of PPO resin and direct pressure molding was performed at 350°C.

Comparative Example 1 Calcined powder C obtained in Example 1 is used alone (Calcined powder A
, B was not used), and a composite substrate was obtained in the same manner as in Example 1, except that the Zr0z fine powder adhesion treatment was not performed. The time required to crush the fired product was approximately 37.5
It was time.

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

Regarding the composite substrates of Examples 1 to 8 and Comparative Example 1.2,
Change rate of relative permittivity εr at -20 to 80'C (IMH
z) was measured. The relative permittivity εr and dielectric loss tanδ at IMHz and IGIlz were also measured. Measurement results first
Shown in the table.

In Example 1, the firing time was 16.5 hours,
This is only half of the grinding time of Comparative Example 1, which was 37.5 hours.

It can be seen that the grinding time is significantly shortened. As shown in Table 1, in the examples, multiple inorganic dielectric powders with different Curie temperatures were used, and the temperature change in relative permittivity was about 3 to 6%, which was 20% of the comparative example. extremely small in comparison. In particular, the temperature change in Example 1, in which a fired product was obtained by mixing a plurality of calcined powders with different Curie temperatures, was different from that in which powders with different Curie temperatures were mixed after obtaining an inorganic dielectric powder. Example 4 with the same conditions
half of the temperature change. In addition, in the composite board,
Since the inorganic dielectric powder is subjected to compressive stress due to the resin, the relative permittivity and dielectric loss versus frequency characteristics are also somewhat improved compared to the characteristics of the dielectric powder itself.

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.

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 present invention, since the bond between the powders in the fired product is weak, the time required for pulverization is shortened, and the powder production time is shortened and costs are reduced.

Further, in the case of the composite substrate of the example, if a plurality of powders having different Curie temperatures are used together, the change in relative dielectric constant with respect to temperature can be improved.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are respectively schematic cross-sectional views of raw material powder used in the manufacturing method of the present invention. 1... Calcined powder 2.3... Substance agent that weakens the bond between powders during firing Patent attorney Takehiko Matsumoto

Claims (1)

[Claims] 1. When firing a raw material powder to obtain a fired product used in the production of inorganic dielectric powder, the raw material powder is a powder on which a substance that weakens the bond between the powders during firing is attached in advance to the surface. A method for producing a fired product for producing inorganic dielectric powder, characterized by: