JPH0323262A - Dielectric ceramic composition for multilayer ceramic capacitors - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to dielectric constant. The present invention relates to a dielectric porcelain composition capable of producing dielectric porcelain having high insulation resistance, high dielectric breakdown voltage, excellent quality Q, small temperature coefficient of capacitance, and high density.

Conventional technology Conventionally, the dielectric constant and insulation resistance are high, and the quality Q is excellent.
The following systems are known as dielectric ceramic compositions with small capacitance temperature coefficients.

@BaO-Tie■-Nd20, system @BaO-Tie2-S+++203 system Problems to be solved by the invention However, these combinations or, for example, 0.09Ba00, 5
When a disk-shaped ceramic capacitor is manufactured using a dielectric material having a composition ratio of 5 Ti02 0.3 6 Na0572, the average value of insulation resistance: 8, Q: XIO"Ω,
Average value of dielectric breakdown strength: 30K▼/ff, which is not a satisfactory value. 1. The density of this dielectric porcelain is
s, eg/t: 1, but generally length L3.2 x width W
1. In glue flow soldering of laminated ceramic capacitors of xx and below, especially in Baber reflow soldering, chip standing (usually referred to as the two-tone phenomenon or the Hunhattan phenomenon) is likely to occur, and it is necessary to prevent chip standing. The problem was that the density of the dielectric porcelain had to be significantly increased.

Means for Solving the Problems In order to solve these problems, the present invention provides the general formula xB
ao-y ((Tie2)(,I.,) (SnO2
) m ) −z R a O 57 2 When expressed as (
However, X0Y+Z=1.0 0, QO 1≦l≦
0.10, Re is one or more rare earth elements selected from La, Pr, Nd, and Sm. ),” + 7v
100 parts by weight of the main component consisting of the range of molar ratios surrounded by points a, b, c, d, a, r shown below, tantalum oxide as a subcomponent, converted to Ta205, is 0.
The present invention proposes a dielectric ceramic composition characterized by containing 1 to 10.0 parts by weight.

FIG. 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 FIG. That is, sintering is extremely difficult in the ▲ region. 1. In region B, the quality Q decreases, making it impractical. Furthermore, in regions C and D, the temperature coefficient of capacitance becomes too large on the negative side, making it impractical.

In the
By selecting 6 from La, Pr, Nd, Sm), L
It is possible to shift the capacitance temperature coefficient in the positive direction without significantly lowering the dielectric constant in the order of a, Pr, Nd, Smo, and b, La, Pr, Nd.
, Sm, or a combination thereof, the capacitance temperature coefficient can be adjusted.

By replacing Tie2 with Sn02, the dielectric constant. Goodness level Q. Capacitance temperature coefficient. It has the effect of increasing the density of dielectric ceramic without significantly changing the values of insulation resistance and dielectric breakdown strength.If the substitution rate m is less than 0.01, there is no substitution effect, while if it exceeds 0.20, the dielectric rate. The quality Q decreases, and the temperature coefficient of capacitance also becomes too large on the negative side, making it impractical.

1.Including the subcomponent Ta205 in the main component has the effect of improving insulation resistance and dielectric breakdown strength, and the content of T&2O5 is 0 per 100 parts by weight of the main component.
．． If it is less than 1 part by weight, the dielectric breakdown strength is not so high;
excluded from the scope of this invention.

On the other hand, the content of TlL2 0 5 is 1 compared to the main component.
0.0! If it exceeds the quantity part, the quality is Q. Insulation resistance decreases,
If the capacitance temperature coefficient becomes too large, it becomes impractical.

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

(Example 1) Starting materials include chemically highly purified BaCo, TiO2,
SnO2, La, O, , Pr60,, Nd
20, , Sm205 and Ta205 powders were weighed to have the composition ratios shown in Table 1 below, placed in a rubber-lined ball mill equipped with agate balls together with pure water, wet mixed, and then dehydrated and dried. This dry powder was placed in a high alumina crucible and calcined in air at 1100'C for 2 hours. This calcined powder was put into a rubber-lined ball mill equipped with agate balls together with pure water, and after wet grinding,
Dehydrated and dried. After adding an organic binder to this pulverized powder and making it homogeneous, the powder is sized through a 32 mesh sieve, and a molding pressure of 1 tOn/c1i is used using a mold and a hydraulic press.
with a diameter of 15 fl. Thickness Q. It was shaped into 4 fl. Then,
The molded disk was placed in an alumina pod covered with zirconia powder and fired in air at the temperature shown in Table 1 below for 2 hours to obtain dielectric porcelain having the composition ratio shown in Table 1.

The thickness, diameter, and weight of the dielectric ceramic disc thus obtained were measured, and the weight was divided by the volume calculated from the thickness and diameter to determine the density of the R electric ceramic.

1. Dielectric constant. The sample for measuring quality Q and temperature coefficient of capacitance was a dielectric ceramic disk with silver electrodes baked onto both sides, and insulation resistance. A sample for dielectric breakdown strength measurement was prepared by providing a 1N wide portion without a silver electrode on the inner side of the outer periphery of a dielectric ceramic disk, and baking a silver electrode thereon.

And the dielectric constant. Goodness level Q and capacitance temperature coefficient are YH
Using a digital LCR meter model 4276▲ manufactured by Company P, the measured temperature was 20"C. The measured voltage was 1,0 Vrrtt+
s, was determined by measurement at a measurement frequency of 1 MHz. In addition,
The capacitance temperature coefficient was determined by measuring the capacitance at 20''C and 85°C using the following formula.

rc=(C-Go),,"cox1,,'ese;xi
o'TC: Capacitance temperature coefficient (p p m./'c
) CO: Capacitance 1 (pi') at 20°C C: Capacitance at 85°C (pF) The dielectric constant was determined using the following formula.

K2143.8〆COXt/D2 K; Dielectric constant Co: Capacitance at 20"C (pF) D = Diameter of dielectric ceramic (H) t; Thickness of dielectric ceramic (IIiw) Furthermore, insulation resistance This is YHP HR meter model 4.
329▲, measuring voltage 5C)/, D, C. , the measurement time was 1 minute.

The dielectric breakdown strength was determined by using a high voltage power supply P H S 3s K-3 type manufactured by Kikusui Electronics Co., Ltd., placing the sample in silicone oil, and measuring the dielectric breakdown voltage determined as follows at a boost rate of 5 ow, 'sea. It was divided by the body thickness to obtain the dielectric breakdown strength per 1n.

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

In the method for producing R electric porcelain in Example 1, B
aCO5, Tie2, SnO2, La205, Pr60
,,, Ha20, , Sm20, O and Ta20,
However, the method is not limited to this method, and compounds such as BaT-03,
Alternatively, by heating carbonates, hydroxides, etc. in the air,
BaO, Ti02, sno2, La20
5, pr6o, , Nd20, , sm, O, j
Even if a compound that becomes rj and Ta205 is used, properties comparable to those of the examples can be obtained.

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

In addition to the basic composition mentioned above, S-02, Mn02,
Salts that are generally considered to be fracnus, such as Fe20, ZnO. Oxides and the like can also be added within a range that does not impair the properties.

(Margins below) Effects of the Invention As described above, according to the present invention, the dielectric constant, insulation resistance. High dielectric breakdown voltage, excellent quality Q, and small temperature coefficient of capacitance allow for smaller products. Larger capacity. Characteristics can be improved. 1.Since it is a dielectric porcelain with a high density, it is possible to improve the chip stand-up during flow soldering when making small surface-mount chip components using this composition.
It is possible to obtain a product with high mountability.

[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 XBaO-y [(TiO_2)_(_1_-_
m_)(SnO_2)_m]-zReO_3_/_2 (however, x+y+z=1.00, 0.01≦
m≦0.20, Re is one or more rare earth elements selected from La, Pr, Nd, and Sm. ), x, y, z are in the range of molar ratios surrounded by the points a, b, c, d, e, f shown below, and tantalum oxide is added as a subcomponent to Ta_2O_5. Converted to 0.1 to 10.
A dielectric ceramic composition characterized in that it contains 0 parts by weight. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼