JPS6126559A - Manufacture of ceramics for high frequency insulating material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing ceramics for high frequency insulating materials using pseudowollastonite (α-Cabin 3).

(Prior Art) Steatite, forsterite, beryllia, and the like have been known as ceramics for high-frequency insulating materials. Each of these has excellent characteristics as an insulating material, but in reality, they are only used in some cases because they have a large loss coefficient, which is the most important property for high-frequency insulating materials.

Recently, high-frequency electronic components, especially integrated circuit ceramic substrates, have come to be required to have higher performance than ever before, and for this reason, products using 8β203 as the main raw material have become mainstream. Insulating materials made mainly from A℃203 have the advantage of excellent electrical properties and mechanical strength, but on the other hand, the firing temperature when manufacturing them is high, and processing of sintered bodies is difficult. There is a problem. Regarding wollastonite, in the 1950s N, H, 5nyder, W
.

Since it was pointed out by M. Jackson et al. that the loss coefficient at high frequencies is extremely small, it has attracted attention as a high frequency insulating material, and various blending ratios have been studied. However, in products made from wollastonite, the water absorption rate is 0.0% regardless of the mixing ratio.
The manufacturing technology for obtaining sintered bodies of 1% or less without deformation has not yet been fully established, and for this reason wollastonite has not yet been industrialized as the main raw material for ceramics for high-frequency insulating materials. .

That is, as wollastonite used as the main raw material for high-frequency insulating materials, low-temperature type wollastonite (β-caSin3) is the most common, and high-temperature type pseudowollastonite (α-cas i03) is the most common.
) was never used. Moreover, even when low-temperature type wollastonite (β-Cabins) is used, the electrical properties deteriorate when it transitions to a high-temperature type (α-type) during the firing process during manufacturing, so the transition temperature is lower than that of the β-Jα type. There were restrictions in that the firing had to be performed at 1125° C. or lower, and the water absorption rate had to be low. When low-temperature type (β type) wollastonite is used for this purpose, for example, BaC0a, Pb(BO2)2 is used as a moderating agent.
, PbS t 03 and Bi2O3 needed to be added. However, in the case of low-temperature type (β-type) wollastonite, even though the firing temperature can be lowered by adding the above-mentioned moderating agent, the temperature range of the firing temperature is at most about ±7°C. The extremely narrow space made sintering work difficult, resulting in a large number of defective products.

On the other hand, when high-temperature type pseudowollastonite (α-Cagin 3) is used as the main raw material, the starting material is completely melted and rapidly cooled in ice water. Journal of the Ceramics Association, 87 [9] 197').

pp. 460-467 and same, 89[4] 1981.
165-170). However, such a method
It is considered that this method cannot be used industrially since it is completely melted at 50° C. and then placed in ice water. Ceramics for high-frequency insulating materials must satisfy the electrical properties necessary for the product, as well as water absorption and deformation during firing, in addition to the manufacturing issues mentioned above. The reality is that these demands are not always met.

(Problems to be Solved by the Invention) This invention attempts to produce ceramics for high-frequency insulating materials with excellent electrical and physical properties using pseudowollastonite (α-CaSiO3) as a raw material. Furthermore, the present invention widens the range of firing temperatures in the manufacturing process to facilitate the manufacture of ceramics for high-frequency insulating materials.

That is, using wollastonite (α-CaSiO3) as a raw material, it has excellent electrical properties such as dielectric properties and volume resistivity, and also satisfies physical properties such as water absorption and bending strength, and the firing temperature range is approximately 100°C. The aim is to expand the scope and make industrial manufacturing possible.

(Means for Solving the Problems) The first aspect of the invention of the present application is characterized in that pseudowollastonite, which has been finely pulverized to 10% or less of the 10μ sieve residue, is pressurized, molded, and fired; The second is the AffzOi component and the MgO component in the first invention.

One or more of ZrO2 components, BaO components, and SrO components are added and contained.

In researching ceramics for high-frequency insulating materials, the inventors first investigated raw materials. That is, although low-temperature type (β-type) wollastonite was conventionally used with additives as ceramics for high-frequency insulating materials, the present inventors dared to use high-temperature type (α-type) pseudowollastonite. I tried. The pseudowollastonite (α-CaSiO3) used in the present invention is synthesized by mixing a calcareous raw material and a silicate raw material, molding and firing, and the synthesized product is of high purity. That is, Fe2O3, N
Chemical components such as a2O and Ni20 adversely affect electrical properties, so they should be kept as low as possible, with a purity of 90% or more, with most of the remainder being SiO2, Fe2O3 and R20 (
However, the total amount of R (Na, K) is preferably 0.5% or less.

In addition, free lime, 2CaO-8iO2 or 3Ca0
・2SiO2 minerals have a negative effect on the grindability during wet grinding, and have a negative effect on the slurry properties of pseudowollastonite or its mixture.

These shall not be included. Therefore, pseudowollastonite is synthesized by mixing highly pure limestone, slaked lime, or quicklime with highly pure amorphous silica, molding, and firing.

The present inventors have developed a pseudowollastonite α-CaS+03 as described above.
) was researched to produce ceramics for high-frequency insulating materials using raw material, and found that by finely pulverizing the raw material pseudowollastonite, the formability was improved, and clay and other materials, which had traditionally been considered indispensable to be added and blended, were discovered. It has been discovered that molding and firing can be performed without using a plasticizer, and that the firing temperature range can be widened. Furthermore, it was confirmed through experiments that the obtained sintered body was dense, had a water absorption rate of 0.1% or less, and had an excellent loss coefficient at high frequencies (IM12) of 0.3% or less.

Experimental Example By-product amorphous silica and limestone are mixed, crushed, molded, and fired in a rotary kiln to produce pseudowollastonite (α-
CaS+03) was synthesized.

Table 1* R20=20 for Na20+ This raw material alone was finely pulverized, molded, and fired to obtain a sintered body. During this firing, the deformation start temperature of the compact is set to 1
The relationship with the 0 μm sieve residue (%) is shown in FIG. 1 (A). Moreover, the water absorption rate of the sintered body obtained by peeling is 0.
The lowest temperature at which the temperature becomes 1% or less is also shown in Figure (B) in relation to the raw material residue (%) after passing through a 10 μm sieve.

As is clear from FIG. 1, the deformation start temperature of the compact during firing increases as the 10 μm sieve residue (%) of the raw material increases, but the rate is gradual. On the other hand, the minimum temperature at which the water absorption rate of the sintered body becomes 0.1% or less is the firing temperature, which increases as the 10 μm-5. The temperature rises rapidly. Therefore, the deformation start temperature (A
) and the lowest temperature at which the water absorption rate of the sintered body becomes 0.1% or less (B
) is as shown by the dashed line (A-B) in the figure.

Next, raw material pseudowollastonite (α-CaSiO3) similar to that used in the one shown in Fig. 1 was finely pulverized and
With molding pressure, ff115myx width 100s+x height 15
am rectangular parallelepiped, and the density of the molded body is 0.1%.
and to avoid deformation during firing, 10μ
The materials were fired at the temperatures shown in Table 2 below, depending on the proportion of the skin sieve residue.

Regarding this sintered body, the relationship between the 10 μm sieve residue (%) of the raw material used therein and the bending strength of the sintered body K9/cd> is shown in FIG. According to Figure 2, the bending strength of the sintered body is 9/a, which is 600, which is required as a high frequency insulating material.
In order to make it 1 or more, the 10 μm sieve residue of the raw material should be 1
It can be seen that it is sufficient to set it to 0% or less.

Incidentally, the loss coefficients of these materials at high frequencies (IMl) were all in the range of 0.26% to 0.27%.

As is clear from the above-mentioned Figure 1, pseudowollastonite 1
If the 0μm sieve residue (%) is 10% or less, the difference between the deformation start temperature during firing and the lowest temperature at which the water absorption rate of the sintered body is 0.1% or less can be 100°C or more. It turns out. Therefore, if we combine this and the relationship shown in Figure 2, we can find that pseudowollastonite (α-CaSiO3) is finely pulverized to 10μ
By setting the m-sieve residue to 10% or less, there is no deformation of the sintered body, and the water absorption rate of the sintered body is also 0.1% or less, and the bending strength of the sintered body is 60089/cd or more. It turns out that it will happen. Furthermore, the firing temperature range in this case is 10
It can be seen that the problem of the firing temperature range, which was extremely narrow in the past, can now be solved in one fell swoop.

Table 3 shows the ceramics for high-frequency insulating materials according to the present invention and those of conventional products, together with the mixing ratio of each raw material, and compares the range of firing temperatures during their production.

As is clear from this, it can be seen that the firing width is greatly expanded by the method of the present invention.

The present invention described above uses only pseudowollastonite as the raw material, but if other additives are further added to this raw material, the firing temperature can be increased to 125
It has been found that the temperature can be lowered to 0 to 1350°C, and the properties of the sintered body can be further improved.

The additives used here include Aμ203 component, MaO
Ingredients, ZrO2 component, BaO component, sr.

One or more of these components are used. These components are mainly added as oxides, hydroxides, carbonates, and silicates. An example of the effect of its addition is as follows. Aj2z 0! When the MgO component and the MgO component are added, the loss coefficient at high frequencies does not improve much, but it has the effect of further lowering the firing temperature. fcK oh, Aj
When adding 2203 component and MgO component, fvl
When added as oO-Aβ203, it has a great effect of lowering the firing temperature.

Addition of ZrO2 component improves bending strength.

If a BaO component is added to this, the loss coefficient at high frequencies becomes even smaller. Addition of the SrO component can also be expected to have substantially the same effect as the addition of the BaO component. Although the amount of these additives cannot be uniformly specified, it is 25 parts by weight or less, preferably 5 to 100 parts by weight of pseudowollastonite.
It is preferable to add in an amount of 15 parts by weight.

EXAMPLE The pseudowollastonite used in the experimental example was pulverized in an alumina bot mill to obtain a powder with a 10 μm sieve residue of 4.3%.

Apart from this + and 1, AN203, tVIgo, ZrO
Special grade reagents of fine powder of 2.S iOz , BaC0a, and 5rCOa, and powder of MqO.Δ1203 passed through a 15 μm sieve were prepared.

The above raw materials were wet-mixed so as to have the composition ratios shown in Table 4, dried in a drier, and then crushed.

The powder thus obtained was molded as follows. Diameter 3 for measurement of dielectric constant and ii dielectric tangent tan δ)
0 tone, 4 ml thick disk shape, 60 m diameter and 3 mm thick disk shape for volume resistance measurement, and 15 mm length x 100 width width x 15 mm height for measuring bending strength. 0.5 in the shape of a rectangular parallelepiped
Pressure molding was performed at a pressure of t/cm. This molded body was fired at the temperatures shown in Table 4 using an electric furnace. A silver paste was baked onto the obtained sintered body as an electrode for measuring the dielectric constant, the tangent of induction (tan δ), and the volume resistivity. Note that the inductivity and induction tangent (tan δ) in the table were measured at 1 MHz, and the bending strength was determined by a three-point bending test. Moreover, the volume resistivity was measured by applying a DC voltage of 500 V for 1 minute.

As is clear from the table, the ceramics of the present invention are:
It can be seen that both have a small loss coefficient at high frequencies and a large bending strength.

Although not shown in the table, the water absorption rate of each sintered body is 0.
．． It was 0%.

〔Effect of the invention〕

According to the present invention, it has become possible to obtain an excellent insulating material with a small loss coefficient at high frequencies by using pseudowollastonite (α-Cagin3) alone.

Moreover, the firing temperature range during production has expanded to 100°C.
Since it has become possible to do the above, manufacturing has become easier. Other products have high bending strength and low water absorption, meeting all the requirements for high-frequency insulating materials.

Furthermore, in the second invention, in which additives are used in combination, there is an effect of further improving the loss coefficient or bending strength at high frequencies.

[Brief explanation of the drawings] Figure 1 shows the relationship between the 10 μm sieve residue (%) of pseudowollastonite powder and the firing temperature, and the deformation start temperature (A
), the lowest temperature at which the water absorption rate of the sintered body is 0.1% or less (B
) and (A-8), and FIG. 2 is a diagram showing the relationship between the 10 μm sieve residue (%) of the pseudowollastonite powder and the bending strength of the obtained sintered 1.

Claims (6)

[Claims] (1) A method for producing ceramics for high-frequency insulating materials, which comprises press-molding and firing pseudo-wollastonite, which has been finely ground to a level of 10% or less of 10 μm sieve residue. (2) The method for producing ceramics for high-frequency insulating materials according to claim 1, wherein the firing temperature is 1300 to 1400°C. (3) Al_2O_3 component, MgO component, ZrO_
1. A method for producing ceramics for high-frequency insulating materials, which comprises adding one or more of two components, a BaO component, and a SrO component, and molding and firing the resulting mixture. (4) The method for producing ceramics for high-frequency insulating materials according to claim 3, wherein the firing temperature is 1250 to 1350°C. (5) Al_2O_3, MgO・Al as MgO component
_2O_3 as ZrO_2 component ZrO_2・Si
Claim 3 characterized in that O_2 is added.
A method for producing ceramics for high-frequency insulating materials as described in . (6) The method for producing ceramics for high-frequency insulating materials according to claim 3, characterized in that ZrO_2.SiO_2 is added as a ZrO_2 component and BaCO_3 is added as a BaO component.