KR920006731B1 - Ceramic material - Google Patents

Abstract

The dielectric magnetic composition is prepared by (A) blending lead monoxide (PbO), zinc oxide (ZnO), niobium pentaoxide (Nb2O5), tungsten trioxide (WO3), manganese dioxide (MnO2), barium titanate (BaTiO3) and strontium titanate (SrTiO3) into a quaternary composition of 0.38-0.5 mol% Pb(Zn1/3 Nb2/3)O3 0.35-0.42 mol% BaTiO3 - 0.08-0.12 mol% SrTiO3 - 0.06-0.1 mol% Pb(Zn1/2W1/2)O3, and (B) adding 0.05-0.2 wt.% mnanganese dioxide (MnO2) to the quaternary composition. Produced composition has stabilized temperature characteristic and can be sintered at the temperature of 1100 deg.C or less. It is used to manufacture laminated condenser using Ag-Pd inside electrode.

Description

[Name of invention]

Dielectric Self Composition

Detailed description of the invention

The present invention relates to a dielectric ceramic composition, the dielectric ceramic composition of the present invention has a stable temperature characteristics, and at the same time can be sintered at a low temperature of 1100 ℃ or less to manufacture a multilayer ceramic capacitor using an Ag-Pd-based internal electrode Can be used.

The conventional X7R multilayer ceramic capacitor material of the EIA (Electronic Industry Association) is mainly composed of BaTiO ₃ , which has a dielectric constant of more than 3000 but has a sintering temperature of about 1250 to 1400 ° C. ) And palladium (Pd) have to be used, and thus there is a disadvantage that the manufacturing cost is high. Accordingly, in order to use cheaper Ag-Pd-based alloys as internal electrodes, excessive amounts of Bi ₂ O ₃ , PbO, TiO _2, and the like are added to BaTiO ₃ and sintered at 1150 ° C. or less is disclosed in JP 61-155245 A. These systems have the drawback that the dielectric constant is lowered to around 2500 and mechanical strength is lowered. In order to solve these problems, a Pb (Zn _1/3 Nb _2/3 ) O ₃ -BaTiO ₃ -SrTiO ₃ system having a high dielectric constant and a firing temperature of 1150 ° C. or less is presented in Japanese Patent Laid-Open No. 61-250904. When sintering at less than 1150 ℃ high dielectric constant is more than 4000 but the sintered structure is not dense moisture resistance is bad, mechanical strength is weak, there was a problem in manufacturing a laminated ceramic capacitor.

Accordingly, the invention provides a dielectric ceramic composition which can solve the above-mentioned problems that are the object, the present invention is _{Pb (Zn 1/3 Nb 2/3) O} 3 of 35 to 38~50mol%, BaTiO ₃ ~42mol%, SrTiO ₃ the 8~12mol, 0.05~0.2wy% in the compositions herein, and are configured to _{Pb (Zn 1/2 W 1/2) O} 3 in 6~10mol% relative to the MnO ₂ is added to the composition To a modified composition.

In the composition of the composition, when the Pb (Zn _1/3 Nb _2/3 ) O ₃ is less than 38 mol%, the dielectric constant is lowered, and when it is more than 50 mol%, a large number of pyrochloid (Pyrochlore) phase is generated and the dielectric constant is lowered. Sintering property is also inferior. BaTiO ₃ is when more than 35mol% becomes croissant different lot Pyro dielectric constant is lowered if at least 42mol% the sintering temperature is lower the higher the more than 1150 ℃ dielectric constant, SrTiO ₃ is the dielectric constant changes in temperature when less than 8mol% It becomes large and does not satisfy | fill Y5R characteristic, and when it becomes 12 mol% or more, dielectric constant will become low. When Pb (Zn _1/2 W _1/2 ) O ₃ is less than 6mol%, the sintering is not complete, and if it is more than 10mol%, the temperature characteristics deteriorate and it does not satisfy the Y5R specification.

If the MnO ₂ is less than 0.05wt%, the dielectric loss is worse than 2% and the insulation resistance is lowered. If it is more than 0.2wt%, the dielectric loss is increased and the insulation resistance is also lowered.

Due to the above structure, the dielectric ceramic composition according to the present invention can lower the sintering temperature to 1100 ° C. or lower, so that 70% Ag-30% Pd can be used as the internal electrode, and the sintered structure is made dense, thereby providing moisture resistance and mechanical strength. It can be obtained a dielectric that satisfies Y5R (permittivity change rate of less than ± 15% from -30 ℃ to +85 ℃) according to the EIA standard, and the ceramic composition of the present invention is densely sintered at 1100 ℃ or less Therefore, the manufacturing cost can be lowered, and the dielectric constant is 3000 or more, which satisfies the Y5R characteristic, and thus, there is an advantage that a highly reliable multilayer ceramic capacitor can be manufactured.

EXAMPLE

PbO, ZnO, Nb ₂ O ₅ , WO ₃ , MnO ₂ , BaTiO ₃ , and SrTiO ₃ were each weighed out in a ball mill to be a ceramic composition shown in Table 1, followed by wet mixing for 24 hours.

The mixed raw materials were dried, calcined at 700 to 850 ° C. for 2 to 4 hours, and then again milled by a ball mill for 24 hours. Thereafter, a 5 wt% PVA solution was used as a binder to form a disc of 12 mm in diameter and 1 to 2 mm in thickness, followed by sintering at 1080 to 1100 ° C. for 2 hours. The silver electrode was applied to both surfaces of the known sintered compact, and baked at 800 degreeC for 20 minutes.

Capacitance and dielectric loss were measured at 1 volt and 1KHz at 25 ℃ using LCR-meter. Temperature characteristics were measured in the range of -30 ℃ to + 85 ℃ while changing temperature using a thermostat. Measured by a resistance meter. The results are shown in Table 1 below.

Comparative Example

Table 1 shows an example of the composition outside the scope of the present invention, prepared in the same manner as in the above Examples and measured in the same manner, the results are shown in Table 1, as shown in Table 1 in the present invention It can be seen that it is significantly lower than the physical properties of the composition according.

TABLE 1

Claims (3)

Of lead oxide (PbO), zinc oxide (ZnO), niobium pentoxide (Nb ₂ O ₅ ), tungsten oxide (WO ₃ ), manganese dioxide (MnO ₂ ), barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ) Pb (Zn _1/3 Nb _2/3 ) O ₃ -BaTiO ₃ -SrTiO ₃ -Pb (An _1/2 W _1/2 ) O _{3 The} dielectric magnetic composition, characterized in that MnO ₂ is added to the system. The molar ratio of Pb (Zn _1/3 Nb _2/3 ) O ₃ -BaTiO ₃ -SrTiO ₃ -Pb (Zn _1/2 W _1/2 ) O ₃ is 0.38 to 0.5, 0.35 to 0.42, A dielectric self composition comprising 0.08 to 0.12 and 0.06 to 0.1. The dielectric ceramic composition of claim 1, wherein MnO ₂ is added in an amount of 0.05 to 0.2 wt%.