KR100245811B1 - Dielectric composition of ceramic capacitor and manufacturing method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric composition of a ceramic capacitor and a method of manufacturing the same, and includes barium titanate (BaTiO ₃ ), bismuth oxide (Bi ₂ O ₃ ), tantalum oxide (Ta ₂ O ₅ ), and lanthanum oxide (La ₂ O ₃ ). It is manufactured by sintering at a constant temperature by adding a main component and subsidiary elements such as niobium oxide, and it has the Y5P temperature characteristic, which has been imported all the way up to improve the temperature characteristics and improve the dielectric constant and leakage current characteristics. The import substitution effect on the dielectric composition of the ceramic capacitor having electrical characteristics of 3,000 or more can be obtained.

Description

Dielectric Composition of Ceramic Capacitor and Manufacturing Method Thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric composition of a ceramic capacitor and a method of manufacturing the same, and more particularly, to a dielectric composition constituting a ceramic capacitor having excellent electrical performance such as dielectric constant, temperature characteristic, and dielectric loss factor, and a method of manufacturing the same.

Ceramic capacitors are capacitors in which a magnet of titanium oxide having a large relative dielectric constant is used for a dielectric.

The outer shape is a form in which two lead wires are shown in one direction on a disk, and the inside of the disk faces a silver electrode with a magnetic disk interposed therebetween.

Thus, ceramic capacitors can be used up to very high frequencies.

Compared to the small size, the capacity is large and the range of 1pF to 1.5μF is being made. The rated operating voltage is about 25V to 500V.

Semicone, which uses high dielectric constant barium titanate for dielectrics, has the drawback of changing its dielectric constant and changing its capacity due to temperature changes.

Typically, the ceramic capacitor is composed mainly of barium titanate high dielectric constant, and zirconate, barium here (BaZrO _3), mixed with additives such as manganese carbonate (MnCO _3), cobalt carbonate (CoCO _3), cerium oxide (CeO ₂₎ It is one kind of capacitor manufactured by firing dielectric ceramic.

In addition, a composite ceramic dielectric having barium titanate as a main component and added calcium zirconate (CaZrO ₃ ) or calcium antimonate (CaSnO ₃ ) as a dielectric composition for high dielectric constant ceramic capacitors has also been widely used.

On the other hand, the titanium oxide-based semicon is used as a temperature compensation capacitor by advantageously utilizing the capacity change due to the temperature change because the temperature coefficient of plus or minus is obtained by arbitrarily selecting the composition of the titanium oxide.

In general, the temperature compensation capacitor is manufactured by firing a ceramic dielectric composed mainly of titanium oxide at a high temperature of 1200 ° C. or higher, and then applying an electrode, which has a high resonant circuit or quality factor (Q) value of an electronic device and a blackout against temperature. Capacitive stability is used in critical circuits.

That is, the temperature compensation magnetic capacitor changes the capacitance according to the change in the temperature of the magnetic dielectric. In this case, the amount of change is expressed as a coefficient and the capacitance of the capacitor and the inductor are combined with each other. It compensates for the frequency not changing with temperature.

Currently, dielectric materials satisfying the electrical performance of the dielectric constant of 3,000 or more and the Y5P temperature characteristic and the dielectric loss coefficient (tanδ) of 2.5% or less are produced in Japan.

Here, the Y5P temperature characteristic means a JIS standard that satisfies a capacity change range of + 10% and -10% or less based on 20 ° C in a temperature range of -25 to 85 ° C.

According to the present invention, the magnetic dielectric composition for ceramic capacitors, which is dependent on the total amount of imports as described above, has a dielectric constant of 3,000 or more, and is formulated to satisfy electrical performance having a temperature characteristic of Y5P. The purpose is to provide a dielectric composition of a ceramic capacitor and a method of manufacturing the same.

The dielectric composition of the ceramic capacitor of the present invention for achieving the above object is 97 to 99 mol% barium titanate (BaTiO ₃ ), 0.01 to ₃ mol% bismuth oxide (Bi ₂ O ₃ ) and tantalum oxide (Ta ₂ O ₅ ) 100 parts by weight of a main component consisting of 0.01 to 3 mol% and lanthanum oxide to 0.01 to 3 mol%, niobium oxide (Nb ₂ O ₅ ), cobalt oxide (CoO), samarium oxide (Sm ₂ O ₃ ), and silicon oxide (SiO). ₂ ), 0.01 to 7 parts by weight of at least one compound selected from aluminum oxide (Al ₂ O ₃ ), nickel oxide (NiO), antimony oxide (Sb ₂ O ₃ ), zinc oxide (ZnO) and lead oxide (PbO) It has its features.

In addition, the step of wet mixing and drying and pulverizing the dielectric composition for ceramic capacitors, calcining at 1160 ~ 1200 ℃, finely pulverized and dried the calcined dielectric, and then adding a binder to prepare a fine powder, a uniaxial extrusion molding molded body The manufacturing method of the ceramic capacitor dielectric material which includes the process of manufacturing the process, and baking for 2 to 4 hours at 1370-1390 degreeC also has the characteristics.

The present invention will be described in more detail as follows.

In the composition of the ceramic capacitor according to the present invention, the main component is barium titanate as in a conventional ceramic capacitor, and the content thereof is preferably 97 to 99 mol% in the dielectric composition of all ceramic capacitors.

If the content of barium titanate is outside the above range, there is a problem that the dielectric constant is lowered or the temperature characteristic is deteriorated.

Here, 0.01-3 mol% of bismuth oxide is added, which is added to improve the temperature characteristic.

If the content is less than 0.01 mol%, the addition effect is insignificant, and if more than 3 mol% is added, there is a problem that the dielectric constant decreases.

And tantalum oxide plays a role of improving the dielectric constant, and the content thereof is preferably 0.01 to 3 mol% in the main component.

If the content of tantalum oxide is out of the above range, a TC (Curie temperature) point having a low dielectric constant leaves the room temperature, adversely affects the temperature characteristics, and the sintered density is low, resulting in a problem in that the structure is not dense.

In addition, the present invention improves the dielectric constant and leakage current characteristics by adding lanthanum oxide, the content of which is 0.01 to 3 mol% of the main component.

If the content of lanthanum oxide is out of the above range, there is a problem that the dielectric constant is increased by 3 mol% or more.

Meanwhile, in the present invention, in addition to the above main components, niobium oxide (Nb ₂ O ₅ ), cobalt oxide (CoO), samarium oxide (Sm ₂ O ₃ ), silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), Select one or more of nickel oxide (NiO), antimony oxide (Sb ₂ O ₃ ), zinc oxide (ZnO) and lead oxide (PbO) and add 0.01 to 7 parts by weight based on 100 parts by weight of the main component Improve the dielectric constant and leakage current characteristics.

Preferably they are niobium oxide, cobalt oxide, or lead oxide among the said subcomponents, More preferably, they are cobalt oxide.

If the content of the minor component is out of the above range, it is difficult to improve the sintering temperature, dielectric constant and dielectric loss coefficient.

The method for producing a dielectric through such a dielectric composition wet mixes and dry pulverizes such a dielectric composition and calcines it to 1160 to 1200 ° C.

A process of preparing a fine powder by pulverizing and drying the calcined dielectric, and then adding a binder to produce a molded body by uniaxial extrusion molding, and then firing it at 1370 to 1390 ° C. for 2 to 4 hours to prepare the dielectric according to the present invention. have.

Hereinafter, the present invention will be described in detail with reference to the following Examples, but the present invention is not limited by the Examples.

Examples 1-7 and Comparative Examples 1-19

Next, the dielectric composition of the ceramic capacitor as shown in Table 1 was placed in a ball mill and wet mixed. Then, it was dried pulverized, calcined at 1170 ° C., and then the pulverized dielectric was pulverized and dried, and 1.5 wt% of the binder was added to prepare a fine powder.

The powder was put into a cylindrical mold having a diameter of 15Φ and uniaxially extruded at 1ton / ㎠ pressure to form a thickness of 2.05mm, fired at 1380 ° C for 3 hours, and coated with silver paste on both sides to measure electrical properties. Is shown in Table 2.

Primary component (mol%) Part (parts by weight) Barium titanate Bismuth oxide Tantalum oxide Lanthanum oxide Compound name content Example One 98.3 0.5 0.7 0.5 Nb ₂ O ₅ 0.1 2 CoO 0.3 3 Sm ₂ O ₃ 0.28 4 NiO 0.25 5 Sb ₂ O ₃ 0.5 6 MnCO ₃ 0.25 7 PbO 0.15 Comparative example One 98.9 0.5 0.5 0.1 Nb ₂ O ₅ 8 2 98.5 0.5 0.7 0.3 - - 3 98.4 0.5 0.8 0.3 - - 4 98.4 0.5 0.6 0.5 ZnO 7.5 5 98.1 0.5 0.7 0.7 - - 6 98.1 0.5 0.7 0.7 Sb ₂ O ₃ 8 7 98.2 0.5 0.7 0.6 SiO ₂ 8 8 98.25 0.5 0.7 0.55 Sm ₂ O ₃ 8 9 98.3 0.5 0.7 0.5 - - 10 Ta ₂ O ₅ 8 11 Y ₂ O ₃ 0.5 12 Nd ₂ O ₃ 0.5 13 - - 14 - - 15 PbO 7.5 16 - - 17 Al ₂ O ₃ 7.5 18 - - 19 - -

Sintering time (hours) Sintering Temperature (℃) permittivity tanδ (%) Temperature characteristic (%) -25 ℃ 85 ℃ Example One 3 1382 3,533 1.48 -8.9 -8.7 2 1380 3,056 0.94 -3.5 6.0 3 1380 3,432 1.03 -8.2 8.6 4 1380 3,099 1.04 -4.3 -7.5 5 1382 3,253 1.00 -9.6 -10.0 6 1380 3,202 0.90 -3.3 -9.2 7 1382 3,287 0.79 -8.2 -9.7 Comparative example One 3 1383 3,781 2.0 -15.4 -6.8 2 1382 2,817 2.0 -4.7 -0.4 3 1382 2,758 1.44 -1.4 -6.1 4 1382 3,526 1.48 -12.9 -2.3 5 1382 3,719 1.17 -10.3 -14.9 6 1382 4,104 1.14 -11.3 -24.2 7 1383 3,338 0.78 -7.4 -11.0 8 1383 4,660 0.8 -50.0 46.0 9 1382 2,877 1.06 -10.1 -17.3 10 1380 3,092 0.93 -2.41 -11.8 11 1382 2,688 1.93 -7.1 18.2 12 1382 3,469 0.7 -12.9 -16.8 13 1382 3,881 1.97 -4.5 -25.1 14 1382 3,522 2.13 -14.8 2.6 15 1380 3,333 0.82 -8.1 -10.1 16 1382 3,012 0.75 2.6 -10.8 17 1382 2,009 1.74 -0.2 -0.1 18 1380 2,654 2.00 -1.7 -0.8 19 1380 2,586 0.94 -5.6 -6.8

From the results of Table 2 above, the dielectric material prepared by adding barium titanate, bismuth oxide, tantalum oxide and lanthanum oxide as main components, and adding a subcomponent such as niobium oxide to the temperature characteristics of Y5P was satisfied. While suitable, the dielectric constant is more than 3,000, and the dielectric loss coefficient satisfies the electrical characteristics of 2.5% or less, it can be seen that the dielectric constant is less than 3,000 and violates the temperature characteristic of Y5P when the composition of the subcomponents is different or out of the content range.

As described in detail above, the dielectric composition of the ceramic capacitor according to the present invention can replace the dielectric material that satisfies the electrical performance such as the Y5P temperature characteristics and the dielectric loss factor, which are imported all the way up, thereby reducing the cost In addition, it can achieve the effect of strengthening international competitiveness.

Claims (2)

Main component consists of 97 to 99 mol% of barium titanate (BaTiO ₃ ), 0.01 to ₃ mol% of bismuth oxide (Bi ₂ O ₃ ), 0.01 to ₃ mol% of tantalum oxide (Ta ₂ O ₅ ) and 0.01 to 3 mol% of lanthanum oxide 100 parts by weight, niobium oxide (Nb ₂ O ₅ ), cobalt oxide (CoO), samarium oxide (Sm ₂ O ₃ ), silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), nickel oxide (NiO) And 0.01-7 parts by weight of at least one compound selected from antimony oxide (Sb ₂ O ₃ ), zinc oxide (ZnO), and lead oxide (PbO). Wet mixing and dry grinding the magnetic dielectric composition for ceramic capacitors of claim 1, Calcining at 1160-1200 캜, Finely pulverizing the calcined dielectric and drying it to make a fine powder by adding a binder, Uniaxial extrusion molding to produce a molded article, and A method for producing a ceramic capacitor dielectric comprising the step of baking at 1370-1390 ° C. for 2-4 hours.