JPH0828127B2 - Dielectric ceramic composition for temperature compensation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a non-reducing dielectric ceramic composition, that is, having high insulation resistance and high dielectric constant even when fired in a reducing atmosphere,
The present invention also relates to a temperature-compensating dielectric ceramic composition having a small dielectric loss.

<Prior Art> Conventionally, a porcelain multilayer capacitor using a high-permittivity porcelain material mainly containing titanate as a dielectric and platinum, gold, palladium or an alloy thereof as an internal electrode has a small size, a large capacity and high reliability. It has been widely used in various consumer and industrial electronic circuits that require high performance.

To manufacture porcelain multilayer capacitors, for example, 50-100
A porcelain green sheet with a thickness of μm is printed, created by a doctor blade method or a spray method, a paste of metal powder to be the internal electrodes is printed and applied on this porcelain green sheet, and a plurality of these are laminated and thermocompression bonded. Then, the integrated product is fired in a natural atmosphere at, for example, 1250 to 1400 ° C. to form a sintered body, and an external extraction electrode that is electrically connected to the internal electrode is baked on the end surface of the sintered body.

<Problems to be Solved by the Invention> However, the conventional titanate-based porcelain has a high sintering temperature of 1250 ° C. or higher, resulting in high firing cost and also as a dielectric ceramic for a multilayer capacitor. When it is used, it is necessary to use expensive Pd or Pt as an internal electrode, which has a high melting point and is hard to be oxidized at a high temperature, which has been an obstacle to cost reduction of the multilayer capacitor. Further, when firing in a non-oxidizing atmosphere, there is a problem that the porcelain is reduced and the insulation resistance is significantly reduced.

<Means for Solving Problems> In view of the above-mentioned conventional problems, a main object of the present invention is to sinter at 1050 ° C. or less, and to obtain a specific resistance of a porcelain even if fired in a non-oxidizing atmosphere. It is intended to provide a dielectric ceramic composition for temperature compensation having a high value of 10 ¹² Ωcm or more.

That is, the present invention provides a main component represented by the general formula {(Ba _1-xyz Sr _x Ca _y Mg _z ) O} _m · (Ti _1-u Zr _u ) O _{2 in} which x, y, z in the above formula , U and m are 0 ≦ x <0.30, 0 ≦ y <0.30 and 0 ≦ z, respectively.
<0.05, 0 <u <0.25, 1 ≦ m <1.03, and 5% by weight or more and less than 40% by weight of the above main component, and the glass component is represented by the general formula aLi ₂ O ・ b
When expressed in _{BaO · cB 2 O 3 · (} 1-a-b-c) SiO 2,
The molar ratios of a, b, and c are 0 ≦ a <0.25 and 0.1 <b, respectively.
A dielectric ceramic composition for temperature compensation, which is contained within the ranges of <0.5, 0.1 <c <0.5, 0.3 <a + b + c <0.8. In addition,
The main component may contain 5 wt% or less of other components such as MnO ₂ and LiF.

<Effects of the Invention> According to the present invention, it can be fired in a specific oxidizing atmosphere at 1050 ° C. or lower, for example, N ₂ gas, Ar gas, CO ₂ gas, CO gas or H ₂ gas, and 10 ¹² Ωcm It is possible to obtain a temperature-compensating dielectric porcelain composition having the above high specific resistance and having a high dielectric constant of 100 or more.

Further, if this temperature-compensating dielectric ceramic composition is used as a dielectric ceramic for a multilayer capacitor, the sintering temperature is as low as 1050 ° C. or lower, so that the firing cost can be reduced, and the resistance value is low and the cost is low. Since copper, copper-engaged gold or other base metal can be used as the internal electrodes, the cost of the multilayer capacitor can be reduced as compared with the conventional one.

The above-mentioned objects, other objects, features and advantages of the present invention will be more apparent from the detailed description of the embodiments given below.

<Example> As raw materials, BaCO ₃ , SrCO ₃ , CaCO ₃ , MgCO ₃ , TiO ₂ and
ZrO ₂ was weighed so as to have the composition shown in Table 1, wet-mixed in a ball mill for 16 hours, and then evaporated to dryness to obtain a mixed powder.

Next, this mixed powder was calcined at 1100 ° C. for 2 hours. A glass component having the composition and amount shown in Table 1 was added to the calcined product, 5 parts by weight of vinyl acetate was added as a binder, and the mixture was wet mixed and pulverized again in a ball mill for 16 hours. The pulverized product was evaporated to dryness, passed through a sieve and sized to obtain a granular powder.

The granular powder thus obtained was pressed by a dry press machine at a pressure of ² ton / cm ² to form a disk having a diameter of 22 mm and a thickness of 1.0 mm.

Then, the disc was baked in an N ₂ gas atmosphere under the respective temperature conditions shown in Table 2 for 2 hours. And
In order to prevent the porcelain from undergoing a change in the characteristics of these fired products when the electrodes were formed, an In-Ga alloy was applied to form electrodes, and samples were prepared.

The following characteristics of these samples were measured under the respective conditions and measuring methods, and the results are shown in Table 2.

(1) Firing temperature (2) Relative permittivity and dielectric loss: frequency 1KHz, temperature 20
℃ condition (3) Capacity-temperature characteristic: It is shown by the temperature characteristic according to JIS standard.
Each characteristic will be described in detail below.

B characteristic: -25 ℃ ~ based on capacitance at 20 ℃
The capacity change rate at + 85 ° C does not exceed -10 to + 10%.

C characteristics: -25 ℃ ~ based on capacitance at 20 ℃
The capacity change rate at + 85 ° C does not exceed -20 to + 20%.

D characteristic: -25 ℃ ~ based on capacitance at 20 ℃
The capacity change rate at + 85 ° C does not exceed -30 to + 20%.

(4) Specific resistance: A value calculated by applying a DC voltage of 500 V at 20 ° C and measuring the current value.

The samples marked with * in Tables 1 and 2 are outside the scope of the present invention, and the other samples are within the scope of the present invention.

Based on Table 1 and Table 2 shown in the above examples,
The reasons for limiting each composition constituting the dielectric paste of the present invention will be described.

General formula {(Ba _1-xyz Sr _x Ca _y Mg _z ) O} _m・ (Ti _1-u Z
In the main component represented by r _u ) O ₂ , the values of x, y, z, u and m are 0 ≦ x <0.30, 0 ≦ y <0.30 and 0 ≦ z, respectively.
<0.05, 0 <u <0.25, and 1 ≦ m <1.03 are within the ranges of x, y, z, u, and m, 0.3, 0.3, 0.05, and 0.
If it exceeds 25 or 1.03, it cannot be fired at 1050 ° C or lower. If m is less than 1, the specific resistance will be less than 10 ¹² Ωcm.

If the glass component is 40% by weight or more, the dielectric constant is 100 or less, and if it is less than 5% by weight, firing at 1050 ° C or less cannot be performed.

The glass component _{aLi 2 O · bBaO · cB 2} O 3 · (1-a-b
-C) when expressed by the general formula SiO _2, a, b, the value of c at a molar ratio of 0 ≦ a <0.25,0.1 <b < 0.5,0.1 <c <0.5,0.
Within the range of 3 <a + b + c <0.8, when a is 0.25 or more, the sample is softened and deformed during firing. Also b
When is 0.5 or more, it becomes impossible to fire at 1050 ° C or lower,
If it is less than 0.1, the dielectric constant will be less than 100. c
When is 0.5 or more or 0.1 or less, firing at 1050 ° C or less is impossible. Furthermore, a + b + c is 0.8 or more or 0.3
Even if the temperature is below, firing at 1050 ° C or lower cannot be performed.

The glass component added to the main component is prepared by previously blending it so that it has a predetermined composition, heat-treating it, melting it, and then vitrifying and crushing it. Even if it is added to the calcined product of the main component without being added, the same effect can be obtained.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number for FI Technical indication H01G 4/30 7924-5E (56) Reference JP-A-59-138003 (JP, A) JP Sho 61-147404 (JP, A) Japanese Patent Sho 62-1596 (JP, B2)

Claims (1)

[Claims] 1. A general formula {(Ba _1-xyz Sr _x Ca _y Mg _z ) O} _m.
In the main component represented by (Ti _1-u Zr _u ) O ₂ , the values of x, y, z, u and m in the above formula are 0 ≦ x <0.30 0 ≦ y <0.30 0 ≦ z <0.05 0, respectively. <U <0.25 1 ≦ m <1.03, and the glass component is contained in the general formula aLi ₂ O · bBaO · cB in an amount of 5% by weight or more and less than 40% by weight with respect to the main component. _When expressed by ₂ O _3. (1-a-b-c) SiO ₂ , the values of a, b, and c are 0 ≦ a <0.25 0.1 <b <0.5 0.1 <c <0.5 0.3 <a + b + c in terms of molar ratio. A dielectric ceramic composition for temperature compensation, characterized in that it is contained within a range of <0.8.