JPH04214070A - Ram material composition for manufacturing porcelain having high dielectric constant - Google Patents

Abstract

PURPOSE:To obtain a raw material compsn. for manufacturing a barium titanate capable of forming into a porcelain even at a low temp. by blending barium titanate with three kinds of components to be added constituted of specified metal oxides. CONSTITUTION:This is a raw material compsn. for manufacturing a porcelain having a high dielectric constant obtd. by incorporating the following three components from A to C into a barium titanate or a porcelain raw material compsn. formable barium titanate. (A) at least one kind selected from the group constituted of antimony oxide, niobium oxide and tantalum oxide, and its quantity is regulated to the one not exceeding 10mol%. (B) (1) at least one kind selected from the group constituted of zinc oxide and cadmium oxide, and its quantity is regulated to <=10mol%, or (2) at least one kind selected from the group constituted of lithium oxide, sodium oxide and potassium oxide, and its quantity is regulated to <=10mol%. (C) at least one kind selected from the group constituted of copper oxide, beryllium oxide and yttrium oxide, and its quantity is regulated to the one not exceeding 5mol%.

Description

[Detailed description of the invention]

0001

[Technical Field] The present invention relates to a raw material composition for producing high-permittivity porcelain, particularly for producing dielectric porcelain that can be sintered at a lower temperature than conventional barium titanate-based compositions. The present invention relates to a composition.

0002

[Background Art] High dielectric constant dielectric porcelain is obtained by firing a raw material composition that provides its constituent components. , or a composition capable of producing barium titanate mixed with Sn, Zr, etc. as a shifter.
It was difficult to sinter unless the temperature was extremely high, from 300 to 1380°C.

On the other hand, conventionally, multilayer ceramic capacitors are
As is known in the art, a thin film sheet with a thickness of 20 to 30 microns is prepared using a mixed solution of a raw material composition and an organic solvent using a doctor blade method, and after drying, a palladium-based electrode paint is printed on the top surface of the sheet. , Further, a thin film sheet of the raw material composition is formed thereon according to the method described above (
In this way, the thin film sheets of the raw material composition and the electrode paint are alternately stacked to form a laminate. The laminate is then cut into the required size in a direction perpendicular to the stacked surface, sintered, and then silver electrodes are baked onto the cut surfaces to complete the process. Of course, the electrodes between the sheets will be alternately joined with silver electrodes so that a capacitor is formed.

By the way, metals or their oxides used in electrode coatings are generally made of noble metals, and at temperatures specific to the metal, the oxide decomposes into metal and oxygen, and is sintered at the same time. It will be baked onto the desired porcelain. Therefore, the electrode coating of the porcelain composition must be baked at a temperature that turns it into porcelain to form the electrode.

However, when using a raw material composition with a high sintering temperature, such as the above-mentioned barium titanate-based raw material composition, a sintering temperature of 1350 to 1380°C is required. When firing barium acid porcelain, it was necessary to use an electrode paint containing mainly palladium. Since palladium metal is expensive, there is a need for inexpensive precious metals, and silver, for example, can be considered as an alternative metal, but silver evaporates at baking temperatures of 850°C or higher. Because of the dissipation, it has been impossible to form silver electrodes on porcelain using conventional barium titanate-based porcelain raw material compositions.

[0006] Conventionally, therefore, an alloy of palladium and silver has been used for barium titanate porcelain in order to make the electrode paint as cheap as possible, but it is still It cannot be said that it is sufficiently inexpensive, and there is a demand for a more inexpensive electrode coating material with a higher silver content. In order to meet this demand, a porcelain raw material composition that can be sintered at the lowest possible temperature is required.
It is needed.

[0007] Furthermore, if the sintering temperature of the porcelain raw material composition is high as described above, the temperature inside the furnace for sintering will increase, and the amount of fuel required to maintain it will increase. At the same time, the furnace material used in such a furnace must also be one that can withstand such high temperatures. The more fuel consumed for this sintering (firing), the higher the fuel cost will be, and furnace materials with excellent heat resistance are also required, but such furnace materials are expensive. Therefore, conventional raw material compositions that require firing at such high temperatures inevitably have the problem of high firing costs.

[0008]

[Problem to be solved] The present invention has been made against the background of the above-mentioned circumstances, and the problem to be solved is a method for manufacturing barium titanate-based porcelain that can be made into porcelain even at low temperatures. The purpose of the present invention is to provide a raw material composition.

[0009]

[Solution] In order to solve such problems, the present invention provides barium titanate or a porcelain raw material composition capable of producing barium titanate containing antimony oxide, niobium oxide, and tantalum oxide. (A) at least 10 mol% of at least one selected from the group consisting of zinc oxide and cadmium oxide, or (B)
Containing 10 mol% or less of at least one selected from the group consisting of lithium oxide, sodium oxide and potassium oxide, and further containing at least one selected from the group consisting of copper oxide, beryllium oxide and yttrium oxide, The reason is that it is contained in a proportion not exceeding mol%.

0010

[Effects of the Invention] As a result, the sintering temperature of the porcelain raw material composition can be significantly lowered, and the silver content in the palladium-silver electrode paint used can be increased, thereby reducing material costs and sintering. As a result, it is possible to achieve a reduction in cost (energy saving), and it can also greatly contribute to reducing product prices when used in multilayer capacitors and the like.

Furthermore, by using such a raw material composition, it has become possible to obtain a dielectric ceramic having a high dielectric constant, low dielectric loss, and a small rate of change in dielectric constant with respect to temperature.

0012

[Specific Structure] By the way, the raw material composition for producing porcelain according to the present invention has barium titanate as a main component, and the barium titanate component is used as barium titanate (BaTiO3) itself. , or as a mixture of barium carbonate (BaCO3) and titanium oxide (TiO2), which can generate BaTiO3 during the sintering process.

[0013] The proportion of the barium titanate component in the raw material composition will be appropriately determined depending on the electrical properties of the intended porcelain, but is generally 85 mol% or more, preferably 90 mol%. % or more will be adopted.

[0014] Furthermore, such a composition may optionally contain various known auxiliary additives such as MnO, CeO2, CoO, V2 O5, etc. as colorants, curing agents, etc.
Although Cr2O3 and the like will be contained, they will generally be controlled in a proportion of 0.5% by weight or less.

The present invention provides a barium titanate-based porcelain raw material composition containing antimony oxide (generally Sb2O3), niobium oxide (generally Nb2O5) and tantalum oxide (generally Generally, it is necessary to contain at least one member selected from the group consisting of Ta2O5 in a proportion not exceeding 10 mol% (indicates the proportion relative to the entire composition; the same applies hereinafter). In addition, the content of too much first auxiliary material,
This is undesirable because it deteriorates the electrical characteristics of the porcelain. In addition, the lower limit of the addition of the first auxiliary raw material is related to the effect of addition and is difficult to limit, but is generally 0.1 mol%, preferably 0.5 mol% or more. On the other hand, a preferable upper limit value is about 5 mol%.

The second auxiliary raw material to be contained in the barium titanate porcelain raw material composition along with the first auxiliary raw material is the following group A compound or B group compound. That is, Group A is at least one compound selected from the group consisting of zinc oxide (ZnO) and cadmium oxide (generally CdO), and they are contained in a proportion of 10 mol% or less in Group A as a whole. . Group B is at least one compound selected from the group consisting of lithium oxide (Li2O), sodium oxide (Na2O), and potassium oxide (K2O), and the total amount of group B is 10 mol%. It is contained in the following proportions. By adding these two compounds of the group of second auxiliary raw materials, the firing temperature can be lowered more effectively.

[0017] If the content of the compounds of group A or group B exceeds 10 mol% in either group as a whole,
Even though it is hardly possible to lower the sintering temperature further, the rate of change in dielectric constant and electrical properties such as dielectric constant decrease with temperature change, which is undesirable. Therefore, the upper limit of the amount for both groups A and B needs to be 10 mol%.

[0018] The lower limit of the amount of Group A and Group B will be determined as appropriate depending on the desired effect of addition and the type of added compound, but in general, for Group A compounds, It is desirable that the content be approximately 0.1 mol % or more, and even for the B group compounds, it is desirable that the content be approximately 0.1 mol % or more.

In the present invention, in addition to the above-mentioned first and second auxiliary raw materials, copper oxide (generally CuO) and beryllium oxide (generally BeO) are used as auxiliary agents.
and yttrium oxide (Y2O3) in a proportion not exceeding 5 mol%, thereby making it possible to sinter at a much lower temperature than conventionally. Note that if such auxiliary agents are contained in large amounts, they will reduce the electrical properties such as dielectric constant, so it is necessary to limit the amount to 5 mol% or less, and the lower limit amount depends on the purpose. Although it varies depending on the effect of addition, it is generally 0.1 mol% or more.

[0020] As described above, the present invention includes a barium titanate-based raw material composition containing a predetermined first sub-raw material and a second sub-raw material, and further adds a predetermined auxiliary agent together with these. By using the obtained raw material composition, the barium titanate system, which is a conventional barium titanate mixture containing Sn and Zr as shifters, was generally not sintered at a high temperature of 1300 to 1380°C. On the other hand, it is possible to lower the sintering temperature to 1140°C or lower, which is considerably lower than that of conventional raw material compositions.

[0021] Therefore, even in palladium-silver-based electrode paints used as electrode paints, the silver content can be increased, or in other words, the amount of palladium can be reduced, so the cost of the paint can be significantly reduced. In addition, it has become possible to effectively reduce fuel costs, furnace structure, furnace material costs, etc., and in turn, it has become possible to extremely reduce firing (sintering) costs. Furthermore, by changing the composition of the auxiliary raw materials added, it is also possible to control the temperature change rate of the dielectric constant and the dielectric constant.

[0022]

[Examples] In order to clarify the present invention more specifically, some examples of the present invention will be shown below.
The embodiments and the description of the above-mentioned specific configuration are not intended to limit any limitations, and various changes, modifications, improvements, etc. may be made based on the knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that this can be done.

[0023] First, the raw materials for each component are wet-mixed in a ball mill or wet-mixed in such a manner that the proportions shown in Tables 1 to 4 are obtained, and then 900 to 11
After calcining at 00° C. for 3 hours to carry out a chemical reaction, the mixture was ground again in a ball mill until the average particle size was about 1 micron. In this example, lithium carbonate, sodium carbonate, and potassium carbonate were used for water-soluble lithium oxide, sodium oxide, and potassium oxide among the component raw materials, and alcohol (methanol or ethanol) was used as the mixing medium. ) was used.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

Next, after drying this mixture, an appropriate amount of polyvinyl alcohol was added as a binder, and it was molded at a pressure of about 1 ton/cm2 to form a shape with a diameter of 16 mm and a thickness of 0.
．． A large number of 5 mm disc-shaped molded products were produced.

[0029] Using this molded product, the molded product was subjected to main firing for 3 hours at various temperatures. Next, regarding the fired product obtained by this main firing,
After observing the degree of porcelainization, those that were porcelainized but not fused were used as samples by baking silver electrodes on both sides, and the electrical characteristics of each were determined by baking such silver electrodes. Measurements were taken after 3000 hours had elapsed, and the measurement results are shown in Tables 5 to 8.

[0030]

[Table 5]

[0031]

[Table 6]

[0032]

[Table 7]

[0033]

[Table 8]

As is clear from the results in Tables 5 to 8, according to the present invention, Nb2 O5, Sb2 O3 and/or Ta2 as the first auxiliary raw material are added to the BaTiO3 component.
O5 is added, and further oxides of Zn, Cd (group A) or Li, Na, K (group B) are added as second auxiliary raw materials, and together with these, Cu, B are added as auxiliary agents.
By using a raw material composition containing oxides of e and Y, the sintering temperature can be lowered from the conventional 1300 to 138
It is possible to adopt a considerably lower sintering temperature compared to the sintering temperature that reaches 0°C, especially for sample No. 19-21, No.
．． 30 to 32, and even No. 50 etc., 1
An excellent sintering temperature reduction effect of 200°C or less was obtained, and the porcelain obtained from them has a high dielectric constant and a small dielectric loss, and the change rate of dielectric constant with respect to temperature is also excellent. It was found to be fully acceptable.

Claims (1)

[Claims] Claim 1: Barium titanate or a porcelain raw material composition capable of producing barium titanate contains at least one selected from the group consisting of antimony oxide, niobium oxide, and tantalum oxide in a proportion not exceeding 10 mol%. and (A) 10 mol% or less of at least one selected from the group consisting of zinc oxide and cadmium oxide, or (B) at least one selected from the group consisting of lithium oxide, sodium oxide, and potassium oxide. 10 mol% of seeds
A raw material composition for producing high dielectric constant ceramics, which contains the following and further contains at least one selected from the group consisting of copper oxide, beryllium oxide, and yttrium oxide in a proportion not exceeding 5 mol%.