JPH03214507A - Dielectric porcelain composite - Google Patents

Abstract

PURPOSE:To obtain the subject dielectric porcelain composite having high dielectric constant, insulation resistance and dielectric breakdown voltage while being excellent in goodness degree Q and having a small electrostatic capacity temperature coefficient. CONSTITUTION:In a formula x [(BaO)(1-m)(CaO)m]-yTiO2-zReO3/2, (x+y+z+1.00, 0.01<=m<=0.30, Re is one or more of rare earth elements to be selected from La, Pr, Nd and Sm), those wherein x, y, z consist of a range of mole ratios surrounded by respective points a, b, c, d, e, f of the table I, are used to constitute a dielectric porcelain composite. Thereby, a goodness degree Q is improved and insulation resistance is heightened without largely changing dielectric constant, an electrostatic capacity temperature coefficient and a value of dielectric breakdown strength.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a dielectric ceramic composition that has high dielectric constant, high insulation resistance, high dielectric breakdown voltage, excellent quality Q, and low temperature coefficient of capacitance.

BACKGROUND OF THE INVENTION Conventionally, the following systems have been known as dielectric ceramic compositions that have a high dielectric constant and insulation resistance, an excellent quality Q, and a small temperature coefficient of capacitance.

・BaO-TiO2-Nd203 system ・BaO-Tio2-Sm203 system Problems to be solved by the invention However, these compositions, for example, 0.09Ba00.5
When a disk-shaped ceramic capacitor is manufactured using a dielectric material with a composition ratio of 6Ti02 0.35NdO3/2, the dielectric constant is 267 and the capacitance temperature coefficient is 2N40ppm/℃.
, Goodness Q: 3000, Insulation resistance: 8. OX101
2Ω, dielectric breakdown strength: 30 kv/mm,
This is not a satisfactory value.

Means for Solving the Problems In order to solve these problems, the present invention provides the general formula x [
(BaO)B-m) (Cab)m]-yTio2z
When expressed as R e 03/2 (x+y+z=1
．． 00. 0.01≦m≦0.30, Re is La. Pr
．． one or more rare earth elements selected from Nd, Sm).

x. y. Each point a, b. c. d. e. The present invention proposes a dielectric ceramic composition characterized by having a molar ratio in the range surrounded by f.

(Margins below) Function Figure 1 is a ternary diagram showing the composition range of the main components of the composition according to the present invention, and the reason for limiting the composition range of the main components will be explained with reference to Figure 1. . That is, sintering is extremely difficult in region A. Furthermore, in region B, the quality Q decreases, making it impractical. Furthermore, in the C and D@ ranges, the capacitance temperature coefficient becomes too large on the negative side, making it impractical. In region E, the temperature coefficient of capacitance shifts to the positive direction, but the dielectric constant is small (not practical).

Also, Re is La. Pr. Nd. By selecting from Sm, La. It is possible to shift the capacitance temperature coefficient in the positive direction without greatly lowering the dielectric constant in the order of Pr, Nd, and Sm, and La. The capacitance temperature coefficient can be adjusted by using one of Pr, Nd, and Sm or a combination thereof.

In addition, by replacing BaO with CaO, the dielectric constant,
It has the effect of increasing the capacitance temperature coefficient and dielectric breakdown strength without changing the values, improving the quality Q and increasing the insulation resistance, but if the substitution rate m is less than 0.01, On the other hand, if it exceeds 0.30, the goodness Q and insulation resistance will decrease, and the capacitance temperature coefficient will also become too large on the negative side, making it impractical.

Example The present invention will be explained below using specific examples.

(Example 1) Chemically high purity BaC○3, CaCO3 are used as starting materials.
, TiO2, La2o3, PrsO, Nd203, and Sm2 (h powders were weighed to have the composition ratio shown in Table 1 below, and put into a rubber-lined ball mill equipped with an agate ball with pure water, and after wet mixing, It was dehydrated and dried. This dried powder was placed in a high alumina crucible and calcined in air at 1100°C for 2 hours. This calcined powder was placed in a rubber-lined ball mill equipped with agate balls together with pure water. After wet pulverization, it was dehydrated and dried. An organic binder was added to this pulverized powder to make it homogeneous, and then it was sized through a 32-mesh sieve, and a molding pressure of 1 ton/cn (with a diameter of 15 mm) was formed using a mold and a hydraulic press. Thickness 0.4m
It was molded into. Next, this molded disk was placed in an alumina pod covered with zirconia powder, and the following first step was carried out in the air.
Firing was carried out for 2 hours at the temperature shown in the table to obtain dielectric porcelain having the composition ratio shown in Table 1.

(Left below) Table 1 The thickness and diameter of the dielectric porcelain disc thus obtained were measured, and the dielectric constant, goodness Q, and capacitance temperature coefficient measurement sample were Silver electrodes are baked onto both sides of the dielectric porcelain disk, and a sample for measuring insulation resistance and dielectric breakdown strength is prepared by providing a 1+nm wide part without silver electrodes inside the outer circumference of the dielectric porcelain disk, and baking the silver electrodes. Ta. And the dielectric constant, goodness Q
, the temperature coefficient of capacitance was measured using a digital LCR meter model 4275A manufactured by Yokogawa/Hewlett-Packard ■ at a measurement temperature of 20°C and a measurement voltage of 1. O V r m
s, determined by measurement at a measurement frequency of IMHz. In addition,
The temperature coefficient of capacitance was determined by measuring capacitance at 20° C. and 85° C. using the following formula.

TC= (C-Co)/CoX1/65X106TC:
Temperature coefficient of capacitance (ppm/°C) Co: Capacitance at 20°C (pF) C: Capacitance at 85°C (pF) Further, the dielectric constant was determined from the following formula.

K = 143.8X Co Using HR meter model 4329A manufactured by Hewlett-Packard Co., Ltd., the measurement voltage was 50V. D. C. ．． It was determined by measurement with a measurement time of 1 minute.

The dielectric breakdown strength was determined by using a high-voltage power supply PH335K-3 type manufactured by Kikusui Electronics Co., Ltd., placing the sample in silicone oil, and dividing the dielectric breakdown voltage determined by a voltage increase rate of 50 V/see by the dielectric thickness. The dielectric breakdown strength was defined as the dielectric breakdown strength per 1 tw+.

The test conditions are also shown in Table 1, and the test results are shown in Table 2 below.
Shown in the table.

(Left below) In addition, in the method for producing dielectric ceramic in the example, Ba
COs, CaCO3, 'rto2, Lat. 3.Prs.
o++, Nd203 and Sm203 were used, but
The method is not limited to this method, but Bad. Cab
．． TiO2, La203. P r 6 01 I * N
Characteristics comparable to those of the examples can be obtained even when compounds forming d 2 0 3 and Sm 203 are used.

Further, even if the main component is calcined in advance and the subcomponents are added, properties comparable to those of the examples can be obtained.

In addition to the above-mentioned basic composition, Si02. MnO2,
Salts, oxides, etc. that are generally considered to be fluxes, such as Fe203 and ZnO, can also be added within a range that does not impair the properties.

Effects of the Invention As described above, according to the present invention, the dielectric constant, insulation resistance, and dielectric breakdown voltage are high, the quality Q is excellent, and the temperature coefficient of capacitance is small, so that the product can be made smaller, larger in capacity, and have better characteristics. Improvement is possible.

[Brief explanation of drawings]

FIG. 1 is a ternary diagram illustrating the composition range of the main components of the composition according to the present invention.

Claims (1)

[Claims] General formula x [(BaO)_(_1_-_m_)(CaO)_m]
-yTiO_2-zReO_3_/_2 (where x+y+z=1.00, 0.01≦m≦0.30
, Re is one or more rare earth elements selected from La, Pr, Nd, and Sm). A dielectric ceramic composition characterized in that x, y, and z are in a molar ratio range surrounded by points a, b, c, d, e, and f shown below.