JPH0210792B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a porcelain dielectric composition suitable for use in capacitors based on barium titanate. (Prior Art) Conventionally, in order to obtain dielectric ceramic compositions suitable for capacitor applications from barium titanate and compositions in which shifters, depressors, etc. It was necessary to conclude. (Problems to be Solved by the Invention) However, when sintering at such high temperatures, it causes wear and tear on the expensive setters such as zirconia and the sintering furnace, and a large amount of energy is required for sintering. The resulting product is expensive. Furthermore, in order to manufacture multilayer capacitors using conventional barium titanate-based compositions, it is necessary to use expensive noble metals such as platinum and palladium that can withstand high sintering temperatures as internal electrode materials. However, the resulting multilayer capacitor is extremely expensive. Therefore, it is a dielectric material that can be sintered at low temperatures, which can reduce wear and tear on setters and sintering furnaces, and also allows the use of inexpensive silver-based internal electrodes when manufacturing multilayer capacitors. Porcelain compositions are highly desired. (Means for Solving the Problems) As a result of various studies, the inventors of the present invention have found that by combining barium titanate with specific amounts of lead oxide and copper fluoride, a dielectric material free of the above-mentioned drawbacks can be created. The present invention was achieved by discovering that the present invention can be obtained. That is, the present invention uses 89.0 to 89.0 as the first component.
99.6 mol% barium titanate as second component
0.2-5.5 mol% lead oxide, 0.2-5.5 mol% as third component
This is a porcelain dielectric composition consisting of 5.5 mol% copper fluoride. A composition that combines barium titanate with specific amounts of lead oxide and copper fluoride can be sintered at low temperatures below 1200°C, and the resulting porcelain dielectric is made by combining lead oxide and copper fluoride individually. Compared to when it is added, the tan δ value is small, the grain size is small and uniform, and the insulation resistance value is high, making it ideal for capacitor applications, especially multilayer ceramic capacitor applications. Furthermore, by combining a specific amount of one or more selected from specific titanate, zirconate, and stannate as the fourth component, the dielectric constant value near room temperature can be increased to 14,000 without impairing the above characteristics. It is possible to make the grain size change even more than that, and it is also possible to make the grain size smaller. The barium titanate used in the present invention may be produced by any method such as a solid phase method, a liquid phase method, an oxalate method, or an alkoxide method. The average particle size is
When using particles as small as 1μ or less and with a uniform particle size distribution, a porcelain with a more uniform microstructure can be obtained, the insulation resistance value will be large, and the variations in various properties will be small. In the present invention, the copper fluoride is CuF ₂ or a hydrated salt. CuF ₂ and 2H ₂ O are used. Lead oxides include divalent, tetravalent, and hexavalent lead oxides, as well as PbO, PbO ₂ , Pb ₂ O ₃ ,
Pb ₃ O ₄ is used. The oxide can be used as it is as lead oxide, but hydroxide, carbonate,
Inorganic salts such as nitrates and organic salts such as oxalates and alkoxides can be used as long as they decompose to form oxides below the sintering temperature. In addition, in the present invention, lead titanate, strontium titanate, barium zirconate, calcium zirconate, strontium zirconate, lead stannate, calcium stannate, strontium stannate,
Barium stannate is PbTiO ₃ , SrTiO ₃ ,
_BaZrO3 , _CaZrO3 , _SrZrO3 , _PbSnO3 , _CaSnO3 ,
SrSnO ₃ and BaSnO ₃ in the form of normal composite oxides are preferably used, but when using various precursors, such as copper titanate, an equimolar mixture of lead oxide and titanium oxide may also be used. It is possible. The proportion of barium titanate in the porcelain composition of the invention ranges from 89.0 to 99.6 mol% as _BaTiO3 . If the proportion is more than 99.6 mol%, 1200℃
Sintering becomes difficult at a temperature below 89.0 mol %, and deformation and fusion of the base material occur, which is undesirable. The preferred range is a temperature of 1200°C or below that has good sinterability and no deformation of the base material.
It is 92.0 to 99.4 mol%. The proportion of lead oxide, which is the second component, is 0.2 as PbO.
~5.5 mol% range. If it exceeds 5.5 mol%, sintering is difficult at low temperatures below 1200°C, and the insulation resistance value is also low. At less than 0.2 mol%,
Almost no effect of addition was observed. The most preferable range for providing good sinterability and sufficiently high insulation resistance is 0.3 to 4.0 mol%. The number of moles here is calculated using one metal element as a unit. For example, in the case of Pb ₂ O ₃ , the calculation standard is PbO _1.5 . The proportion of copper fluoride, which is the third component, is in the range of 0.2 to 5.5 mol%. If it is more than 5.5 mol%,
Deformation and fusion of the substrate become more likely to occur, and the value of dielectric loss increases. Moreover, the sinterable grain size becomes non-uniform and large. If it is less than 0.2 mol%, low temperature sintering becomes difficult. A preferable range in which the grain size of the sintered body is small and uniform, almost no deformation of the base material is observed, and the dielectric loss is small is in the range of 0.3 to 4.0 mol%. Further, the best results with good insulation resistance and low dielectric loss are obtained when the molar ratio of lead oxide and copper fluoride is 1:3 to 3:1. Furthermore, in a preferred embodiment, one or more selected from lead titanate, strontium titanate, barium zirconate, calcium zirconate, strontium zirconate, lead stannate, calcium stannate, strontium stannate, and barium stannate. The composite oxide contains the first component, the second component, and the third component.
It is added in an amount of 2.5 to 40.0 moles per 100 moles of the total amount of components. If the amount is less than 2.5 mol, the effect of addition is not very pronounced, the grain size does not decrease, and furthermore, the dielectric constant value does not increase very much. When the amount exceeds 40.0 mol, the dielectric constant value tends to be small and the insulation resistance value tends to be small. A particularly high dielectric constant can be obtained in the range of 5.0 to 25.0 mol %. When using barium stannate or calcium stannate or a mixture thereof,
It becomes easier to obtain a material with a large dielectric constant. (Examples) Hereinafter, the present invention will be explained in detail by way of examples. Example 1 Barium titanate, copper fluoride, and lead oxide were weighed in the proportions shown in Table 1, and mixed in an agate ball mill using vinyl acetate as a binder and acetone as a solvent. After drying the mixture, it was granulated through an 80-mesh sieve, and a disk-shaped molded product with a diameter of 15 mm and a thickness of 0.6 mm was produced under a pressure of 2 t/cm ² .
Next, 10 of these were stacked on a zirconia setter and sintered under the sintering conditions shown in Table 1. Silver electrodes with a diameter of 10 mm were baked on both sides of the resulting porcelain disc, and various properties were measured. Dielectric constant and dielectric loss (tanδ)
Measurement was performed using an LCR meter at 1KHz, 1V, and 20℃. Insulation resistance value is measured using a high insulation resistance meter.
A voltage of 500V was applied and measured. In addition, a scanning electron micrograph of the porcelain surface was taken to determine the grain size. The sintered density was determined by dividing the weight of the disc by the volume measured using a micrometer. The measurement results are shown in Table 2. Sample No. 1, 2, 3
Sample Nos. 4 and 5 are outside the scope of the present invention, and Samples Nos. 4 and 5 are within the scope of the present invention. As is clear from Table 2, products within the scope of the present invention can be sintered at temperatures below 1200°C, have a small tan δ, high insulation resistance, a large sintered body density, and a small grain size. .

【table】

[Table] Example 2 The results of the system in which the fourth component was added are shown. Various compounds were weighed in the proportions shown in Table 3, ethyl alcohol was added, and ball milling was performed using a nylon ball to mix thoroughly. After drying the resulting mixture,
A paste was prepared using an acrylic resin as a binder and trichloroethane as a solvent using a Meno ball mill. A green sheet with a thickness of 30 μm was prepared by the doctor blade method. 23 of these green sheets were stacked and laminated at a temperature and pressure of 70° C. and 100 kg/cm ² , and then cut into squares with an opening of 12 mm. After sintering under the conditions shown in Table 4, silver electrodes were baked on both sides, and various properties were measured in the same manner as in Example 1. The average grain size was determined from the scanning electron micrograph of the porcelain surface using the line intercept method. The measurement results are shown in Table 4. Samples Nos. 1 and 3 are outside the scope of the present invention, and Samples Nos. 4 and 8 have amounts of the fourth component that are outside the scope of the preferred embodiment of the present invention. Table 4
As is clearer, by adding the fourth component, the tan δ remains small and the insulation resistance remains high at 20°C.
It can be seen that the dielectric constant can be increased to over 14,000 and the grain size can also be reduced. In addition, the amount of the fourth component is shown as an internal division.

【table】

【table】

[Table] In the above examples, barium titanate is
A material with a leakage ratio of Ba and Ti of approximately 1 was used, but
Even if the ratio deviates by about 0.05 mole, good characteristics can be obtained. Further, when a trace amount of aluminum oxide, silicon dioxide, etc. is added to the composition of the present invention, it is effective in improving the characteristics. (Effects of the Invention) As described above, the dielectric ceramic composition of the present invention can be sintered at a low temperature of 1200° C. or lower, has a small tan δ, a uniform and small grain size, and has a large insulation resistance. In addition, the dielectric constant at room temperature can be increased to over 14,000 without impairing these properties, making it extremely effective as a ceramic composition for laminated ceramic chip capacitors, and its industrial value is great.

Claims (1)

[Claims] 1 Consisting of 89.0 to 99.6 mol% barium titanate as the first component, 0.2 to 5.5 mol% lead oxide as the second component, and 0.2 to 5.5 mol% copper fluoride as the third component. Porcelain dielectric composition. 2 The first component is 92.0 to 99.4 mol%, the second component is 0.3
4.0 mol% and the third component is 0.3 to 4.0 mol%. 3 The molar ratio of the second component and the third component is 1:3 to 3:
1. The porcelain dielectric composition according to claim 1 or 2, which is 4 A fourth component is added to a composition consisting of 89.0 to 99.6 mol% barium titanate as the first component, 0.2 to 5.5 mol% lead oxide as the second component, and 0.2 to 5.5 mol% copper fluoride as the third component. The first component and the second component are one or more selected from lead titanate, strontium titanate, barium zirconate, calcium zirconate, strontium zirconate, lead stannate, calcium tin, strontium stannate, and barium stannate. , a porcelain dielectric composition containing 2.5 to 40.0 moles per 100 moles of the third component. 5. The ceramic dielectric composition according to claim 5, wherein the fourth component is 5.0 to 25.0 moles. 6. The porcelain dielectric composition according to claim 5 or 6, wherein the fourth component is barium stannate and/or calcium stannate.