JPH02123612A - Porcelain dielectric composition - Google Patents

Abstract

PURPOSE:To reduce the permittivity temperature characteristic, leaving the high permittivity as it is, and obtain the composition having the low loss and a little frequency dependency by adding the specific adding material with the specific weight ratio to the multiple kinds of the specific titan acid metal with the respective specific weight ratio to compound the porcelain dielectric composition. CONSTITUTION:0.05-0.70weight% of the adding material CuO is added to 100 weight part of the compounded composition compounded of 30.0-70.0weight% of SrTiO3, 0.0-40.0weight% of PbTiO3, 8.0-40.0weight% of Bi2O3, 3.0-20.0weight% of TiO2, and 1.0-10.0weight% of MgO so as to compound the porcelain dielectric composition. Thereby, the permittivity temperature characteristic is reduced, leaving the high permittivity as it is.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a porcelain dielectric composition, in particular a ceramic dielectric composition having a high dielectric constant,
The present invention relates to a ceramic dielectric composition that has excellent temperature characteristics of dielectric constant, low loss, and small frequency dependence.

[Conventional technology]

In recent years, switching power supplies have become smaller and lighter, have higher frequencies, and CR
As the definition of T-displays becomes higher, there is a demand for smaller ceramic capacitors with lower dielectric loss (tan δ).

Conventionally, as a high dielectric constant ceramic dielectric composition, BaT
Although iOs-based porcelain has been widely put into practical use, this type of ceramic has a large dielectric loss (Lan δ) (especially at high frequencies, it becomes significantly large).

[Problem to be solved by the invention]

To address the above problem, 5rTi03PbTiO
Compositions of s-Bit's'-Tilt-MgTi03 have been proposed. However, even with this method, the dielectric constant temperature characteristics and the dielectric loss (tan δ) at high frequencies are large, so that it is still unsuitable for practical use.

Therefore, an object of the present invention is to provide a porcelain dielectric composition that improves these problems.

[Means to solve the problem]

In order to achieve the above object, the present inventors conducted extensive research and found that a desired porcelain dielectric composition can be provided by adding CuO to the above composition system.

That is, 30.0 to 70.0% by weight of 5rTiOs,
PbTiOs 0.0 to 40.0% by weight, Bi2O* 8°0 to 40°0% by weight, Ti1t 3.0 to 20.0% by weight
Blend composition 1 of 1.0 to 10.0 wt% MgO
00 parts, CuO is added as an additive from 0.05 to 0.7
Add 0% by weight.

This makes it possible to reduce the dielectric constant-temperature characteristics while maintaining a high dielectric constant, thereby providing a ceramic dielectric composition with low loss and low frequency dependence.

〔Example〕

The present invention will be explained in detail based on examples.

SrCO3, Ti0zSPbO1Bizos as raw materials
, MgCO3 and the additive CuO are sintered, then weighed and blended to have the composition ratio shown in Table 1, and wet mixed in a bot mill. After that, it was dehydrated and calcined at 900℃ to 200℃.
Next, this is pulverized, an organic binder is added, and after granulation, it is pressure-molded to a diameter of 16 m+-1 and a thickness of 016 m-. This molded product was then fired in an air atmosphere at a temperature of 1160°C to 1260°C for 2 hours. Silver electrodes were baked on both sides of the porcelain fired body thus obtained to create a capacitor, which was used as a measurement sample.

After that, the dielectric constant ε8 and dielectric loss (ta
nδ (%)) (Measurement frequency I KHz, 100 KHz)
The characteristic values of dielectric constant temperature characteristic change rate (8C/C (%)) were measured and shown in Table 1.

In Table 1 in the second margin below, sample No. 1.2.6°8,9.
10.11, 12.15.16.19°20 are outside the scope of the present invention. The measurement conditions for the measured values shown in Table 1 are as follows.

Dielectric constant (ε, ); room temperature I KHz Dielectric loss (tan δ (χ)); room temperature I KHz, 1
00 to BZ dielectric constant temperature characteristic change rate; ΔC/C(χ)) based on the dielectric constant at 20°C) Values in the range of -25°C to +85°C As is clear from this Table 1, within the scope of the present invention The sample has a high dielectric constant, a good rate of change in dielectric constant temperature characteristics, and a good dielectric loss, and is characterized by a particularly small dielectric loss at 100 Hz.

The reason for limiting the range of each component in the present invention as described above is as follows.

When 5rTiOa is 30°0% by weight or less in the main components, the dielectric loss at I KHz and 100 KHz and the rate of change in dielectric constant temperature characteristics are large (for example, sample No. 1 in Table 1).

8), and if it is 70.0% by weight or more, the dielectric constant is 100.
The value becomes smaller than 0 (for example, see No. 10 above).

Although PbTi0* has a dielectric constant of 1000 or more even at 0.0% by weight (for example, see No. 7 above), it has a dielectric constant of 40.0
If it exceeds % by weight, the dielectric constant loss and the rate of change in dielectric constant temperature characteristics become large (for example, see No. 1 above).

B11103 has a dielectric constant of 100 at 40.0% by weight or more.
0 or less (for example, see No. 6 above), 8
．． If it is less than 0% by weight, the rate of change in dielectric constant temperature characteristics becomes large (for example, see No. 9 above).

Ti1t is 1Hz and 100Kl at 3.0% by weight or less.
The dielectric loss of lz is large (for example, No.

(See No. 12), if the amount is 20.0% by weight or more, the rate of change in dielectric constant temperature characteristics becomes large (for example, see No. 15 above).

At 0.0% by weight, MgO has a small dielectric constant of 1000 or less (see No. 11 above, for example), making it difficult to burn out;
．． Even if it is 0% by weight or more, the dielectric constant is 1000 or less (see No. 20 above, for example).

The additive CuO has a small dielectric constant of 1000 or less when it is 0.70% by weight or more based on 100 parts of the main composition (see No. 19 above, for example), and the rate of change in dielectric constant temperature characteristics is large when it is 0.05% by weight or less. (For example, the above No. 2.N
(see No. 16) or the dielectric loss at 100 KHz increases (for example, see No. 2 above).

By the way, Figure 1 shows the dielectric constant and rate of change in dielectric constant temperature characteristics when CuO is added and mixed, and shows the state of samples No. 0016.17 and 18.19 in Table 1. The reason for the limitation is clear. That is,
When CuO is less than 0.05% by weight, the rate of change in dielectric constant-temperature characteristics increases rapidly, and when CuO is less than 0.05% by weight, the rate of change in dielectric constant temperature characteristics becomes large.
It is clear from FIG. 1 that the dielectric constant becomes too small at 8% by weight or more.

Furthermore, Fig. 2 shows the frequency and dielectric loss characteristics depending on the amount of CuO added.
8.19 is shown. According to this FIG. 2, the characteristics of No. 16 are poor;

Although No. 19 has good characteristics, as described above, No. 19 has the drawback of a small dielectric constant.

In addition, in the above examples, the starting materials were each 5rTio.
a, PbTi0a, MgT i O3, Bigos・n
Each component may be prepared in advance and mixed together like T i Ox, and PbO may be Pb3O4, Mg
Co5 may be MgO1 or other compounds that can provide the same properties as long as they have the above-mentioned composition after sintering.

[Effects of the Invention] The present invention provides SrTi03-PbTiOa-MgTiO3-B, which provides a ceramic capacitor with lower loss than before.
C as a new additive to the i go3-TiOg composition
By mixing uO, it is possible to improve the rate of change in dielectric constant temperature characteristics with a high dielectric constant, and further to reduce dielectric loss at high frequencies.

[Brief explanation of the drawing]

FIG. 1 shows sample No. 16 in Table 1. 17. 1
8.19 Dielectric constant (ΔC (%) when mixed with CuO
)) and the rate of change in dielectric constant-temperature characteristics. FIG. 2 shows the frequency characteristics of dielectric loss (tan δ) when samples No. 16.1T and 18.19 were mixed with CuO.

Claims (1)

[Claims] SrTiO_3 30.0-70.0% by weight PbTiO_3 0.0-40.0% by weight Bi_2O_3 8.0-40.0% by weight TiO_2 3.0-20.0% by weight MgO 1.0 ~10.0% by weight Additive CuO0.05~ per 100 parts of the above blended composition
A porcelain dielectric composition characterized by adding 0.70% by weight.