JPS6297205A - High specific inductive capacity system dielectric porcelaincompound - 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 [Field of Industrial Application] The present invention relates to a high dielectric constant dielectric ceramic composition for a ceramic capacitor, particularly a laminated ceramic capacitor that can be fired at a low temperature.

[Prior art]

Conventionally, multilayer ceramic capacitors generally consist of laminating a plurality of sheet-like dielectric materials whose main component is BaTi0z (barium titanate), each coated with internal electrodes on the surface, and the internal electrodes of each sheet are alternately arranged in parallel to form a pair of dielectrics. It is connected to an external connection electrode and is formed by sintering and integrating it. Such laminated ceramic capacitors have come to be used in a wide range of electronic circuits as electronic components have rapidly become smaller with the recent advances in electronics.

However, this conventional dielectric material mainly composed of BaTi0:+ needs to be fired at a high temperature of 1250°C to 1350°C, and when this material is used as the dielectric of a multilayer ceramic capacitor, the internal electrodes are Because palladium (melting point: 1555°C), an expensive precious metal that does not melt or oxidize at the dielectric firing temperature, or its alloy is used, it is difficult to use the internal electrodes, especially for those with large capacitance. The number of conventional multilayer ceramic capacitors is large, resulting in high costs.Despite the above-mentioned conventional multilayer ceramic capacitors having high capacitance efficiency, excellent low dielectric properties, and high reliability, price is a major obstacle to their progress. It had become. Therefore, silver (
In order to use inexpensive metals such as copper (melting point 960°C) and copper (melting point 1083°C) as internal electrodes, it is necessary to
There has been a strong desire for a dielectric material with a high dielectric constant that can be sintered at temperatures below 50°C.

In recent years, several proposals have been made for high permittivity dielectric materials as ceramic compositions that can be sintered at low temperatures of 1000° C. or lower. As ferroelectric materials, they can be sintered at low temperatures.
Pb(FezzzNb1/2)Oz, Pb(Fez/z
W1/3)03, Pb(Mg1/2W1/2)(h,
Pb(Zn+zJbzzz)Oz, Pb(Mg+7zN
bzzz)Oi, Pb(Ni+/zNbzzz)Oz,
This is an attempt to obtain desired dielectric properties at room temperature by combining two or three components of pbTi (h) and pbTi (h).

However, these have disadvantages such as large dielectric loss or low insulation resistance when the relative dielectric constant is large. Furthermore, since all of the synthetic components are ferroelectrics, it is impossible to avoid the fundamental drawback that the dielectric loss is extremely large at the Curie temperature and in the low temperature range near the Curie temperature.

Incidentally, it was disclosed in Japanese Patent Application Laid-Open No. 52-21699 (S
rx Pb+-x Ti0z) a (Pb(Mg1
/2W+/z)0:+) In l-A, x=0 to 0.
10. A composition in which A=0.35 to 0.50 has been put into practical use, and dielectric powder of the above composition is commercially available. However, although this composition system can be sintered at a low temperature of 1000°C or less and has excellent insulation resistance, the dielectric loss is about 1.5χ, and when applied as a multilayer ceramic capacitor, the dielectric loss is about 1.5χ. loss of at least 1%
The following conditions are not satisfied.

[Purpose of the invention]

The present invention was devised as a result of various experiments in view of the above-mentioned drawbacks.
3, Ba(Cr
Pb(
To provide an excellent high-permittivity dielectric ceramic composition that improves the dielectric properties originally possessed by Fe+7□Nb+z□)Ol and has low dielectric loss, high insulation resistance, and good temperature dependence of relative permittivity. There is a particular thing.

[Means for solving problems]

The high permittivity dielectric ceramic composition of the present invention has a composition formula of Pb
(F13+7z -11Sm X Nb17g)03
In the composition represented by 0.021≦x≦0.
It is characterized by being in the range of 0.070.

The reason for limiting the range of x to the above range is that the dielectric properties required for a ceramic capacitor, especially a multilayer ceramic capacitor, are as follows: a relative dielectric constant of 7,500 or more, and a dielectric loss of 1.
．． This is because it does not satisfy any of the following dielectric properties: 0θ% or less, insulation resistance of 3.0XIO"Ω or more, and good temperature dependence of relative dielectric constant.
When 021 < OXIO”
This is because the dielectric properties are not satisfied if the resistance is less than Ω.

〔Example〕

Next, the present invention will be explained based on examples.

Pb0z+FezO:+, NbzOs+ as starting materials
and Sm, 03 were weighed so as to have the composition ratios shown in Table 1, and wet mixed together with a dispersant and a dispersion medium in a ball mill. This raw material slurry was dried and heated to 950°C.
It was calcined for 3 hours at a temperature of . Next, after coarsely crushing this calcined material,
Finely pulverized with a vibrating mill, resulting in an average particle size of 0°7~0
．． Approximately 1 part by weight of polyvinyl alcohol is added to 8 μm fine powder.
．． After adding X and granulating it, approximately 900Kg/c
At a pressure of d, the diameter is about 12 mm and the thickness is 1. It was molded into an omm disc shape. After burning off the polyvinyl alcohol of this disc-shaped molded body at 500°C, it was fired in an oxygen-containing atmosphere at a temperature of 900°C to 950°C for 2 hours.

Finally, 8 silver electrodes were placed on both the upper and lower surfaces of the obtained disc-shaped fired body.
Baked at 00°C. Similarly, Pb (
FezzsW+zi)Oz, pb which is the same ferroelectric material
The composition formula of (Fe1/2Nbtzz)0+ as a solid solution is P
b(Fezz:+W1/l)X (Fe1/2Nb1/
2) A dielectric ceramic composition represented by 1-x 03 and where X=0.5 was used as a comparative example. Table 1 shows the characteristics of the disc-shaped capacitor sample thus obtained.

However, the relative dielectric constant in the table is 1.0KHz, 1. OVrm
Shows the capacitance value at room temperature measured with a capacitance bridge using an input signal of s and the value calculated from the sample dimensions.
:1, indicates the measured value in the OVrms human input signal. Insulation resistance can be determined from the volume resistivity (Ω・am
), and the temperature characteristic of the relative dielectric constant is -3
Capacitance was measured at each temperature of 0℃, +25℃, and +85℃ under the same conditions as above, and the rate of change in capacitance at each temperature with respect to the capacitance at +25℃ was calculated, and ε- 3°/ε2. and expressed as ε85/ε25.

As is clear from Table 1, Sample No. 1 has a small dielectric ratio and extremely large temperature dependence of the dielectric constant, and Sample No. 12 has a small dielectric constant and low insulation resistance. Further, in the comparative example, the dielectric loss was extremely large and the insulation resistance was also extremely low, so that practical dielectric properties were not obtained in either case.

In contrast, the dielectric ceramic composition within the scope of the present invention has a sufficiently large dielectric constant of 8250 to 16760, a small dielectric loss (Tan δ) of 0.13 to 0.57, and a low insulation resistance (Ω・C11). ) is 5.8 x 101' to 3.3 x 1
012, and the above-mentioned relative dielectric constant temperature characteristics are also good, and all have excellent dielectric properties, but it is understood that sample numbers 5 to 8 are particularly desirable.

〔Effect of the invention〕

The dielectric ceramic composition within the scope of the present invention has a relative dielectric constant,
All of the characteristics of dielectric loss (Tan δ), insulation resistance (Ω·cIn), and temperature characteristics of relative permittivity are satisfactory.

Further, in the present invention, the firing temperature is 900°C to 95θ°C.
Since it can be fired within a range of It is understood that there is a gender.

Applicant (663) Kyocera Corporation Kazuo Inamori

Claims (1)

[Claims] The compositional formula is Pb(Fe_1_/_2_-_xSm_xNb_1_/
_2) In the composition represented by O_3, x is 0.02
A high dielectric constant dielectric ceramic composition, characterized in that the dielectric ceramic composition is in the range of 1≦x≦0.070.