JP3036128B2 - Grain boundary oxidation type voltage non-linear resistance composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain boundary oxidation type non-linear resistance composition, and more particularly to, for example, a varistor used for absorbing or removing abnormal voltage and noise generated in electronic equipment and electric equipment. The present invention relates to a grain boundary oxidation type voltage non-linear resistance composition as a material.

[0002]

2. Description of the Related Art A voltage non-linear resistor mainly composed of strontium titanate has not only a function as a varistor for absorbing abnormal voltage and noise, but also a function as a capacitor. Such varistor materials include, for example, JP-A-58-16504 and JP-A-58-916.
No. 02, SrTiO ₃ or Sr _1-x Ca _x TiO ₃ (0.01 ≦ x ≦ 0.5)
As a main component, and Nb as a component for semiconductor conversion.
₂ O ₅ , Ta ₂ O ₅ , WO ₃ , La ₂ O ₃ , CeO ₂ ,
Some contain metal oxides such as Nd ₂ O ₃ and Y ₂ O ₃ and Na ₂ O for providing varistor characteristics.

[0003]

In these conventional compositions, it is possible to improve the varistor characteristics such as the nonlinear coefficient and the surge resistance by diffusing the alkali metal oxide Na ₂ O into the grain boundaries. It is possible. On the other hand,
Varistors using these compositions have the disadvantage that the moisture resistance, particularly the change over time in the characteristics in a high humidity atmosphere, is large. This is because the alkali metal has a high ionization tendency, and therefore reacts with the external electrode or the glass frit in the electrode in a high humidity atmosphere to corrode the electrode, or the corrosion increases the resistance and changes the characteristics. .

[0004] Therefore, a main object of the present invention is to provide a grain boundary oxidation type voltage non-linear resistance composition which can obtain a voltage non-linear resistance with little change over time even when used in a high humidity atmosphere. It is to be.

[0005]

According to the present invention, (Sr
_1-xy Ba _x C a _y ) TiO ₃ (where 0 <x ≦ 0.
3 , y ≦ 0.25) from 98.0 to 99.9 mol%,
b, W, Ta, In and at least one kind of oxide selected from rare earth elements is 0.1 to 2.0 mol% with respect to a main component comprising CuO, PbO, Bi ₂ O ₃ ,
At least one selected from Sb ₂ O ₃ , V ₂ O ₅ and MoO ₃ and Na _p M _{q Or} (where M is Mo, W
At least one of p = 2n, q = 2n ′, r =
n + 3n ′, wherein n and n ′ are 0.01 to 2.0 mol% in total of 1 or 2), which is a grain boundary oxidation type voltage non-linear resistance composition.

[0006]

By using the grain boundary oxidation type voltage non-linear resistance composition of the present invention, it is possible to obtain a voltage non-linear resistance having little change over time in characteristics even when used in a high humidity atmosphere.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the accompanying drawings.

[0008]

EXAMPLE First, in order to obtain a main component, SrCO ₃ , T
iO ₂ , CaCO ₃ , BaCO ₃ and oxides of Nb, W, Ta, In and rare earth elements were prepared as semiconducting agents. These raw material powders were weighed so as to obtain compositions having the composition ratios shown in Tables 1 and 2, and wet-mixed to obtain a mixture.

[0009]

[Table 1]

[Table 2]

After drying the resulting mixture at 1150 ° C. for 2 hours
The mixture was calcined for an hour and pulverized to obtain a pulverized product. 5% by weight of a vinyl acetate resin is added to the pulverized product and granulated, and the granulated product is formed under a pressure of 1 ton / cm ² to obtain a pellet-shaped formed body having a diameter of 10 mm and a thickness of 1.5 mm. Was. After firing the obtained molded body in air at 1000 ° C. for 2 hours,
It was fired at 1450 ° C. for 2 hours in a mixed gas atmosphere of H ₂ : N ₂ = 1: 100 in volume ratio to obtain a semiconductor porcelain.

On the other hand, Na ₂ O and an oxide of Mo or W are melted at a fixed ratio to obtain Na ₂ MoO ₄ , Na ₂ M
o ₂ O ₇ , Na ₄ MoO ₅ , Na ₂ WO ₄ , Na ₂ W ₂
To give compounds such as O _7. These compounds and CuO,
_{PbO, Bi 2 O 3, Sb} 2 O 3, V 2 O 5, MoO 3
And the like were mixed and pulverized to obtain a mixture powder. Then, the semiconductor porcelain and the mixture powder are mixed, and 1200 ° C.
For 2 hours to obtain a porcelain unit.

A silver electrode was provided on the facing surface of the porcelain unit to obtain a voltage non-linear resistor element. Then, the electrical characteristics of the obtained voltage nonlinear resistor element were measured. Here, the varistor voltage V when a current of 1 mA flows through the element
_{1 mA} (V), nonlinear coefficient α, capacitance (nF), 500
Variation rate of varistor voltage ΔV _1mA (%) when a surge current of 0 A / cm ² is applied and variation rate Δα of nonlinear coefficient
(%) Was measured and shown in Tables 3 and 4.

[0013]

[Table 3]

[Table 4]

Further, a voltage non-linear resistor element made of the material shown in Sample No. 4 in Table 1 and a Sr _0.80 Ca _0.20 TiO
₃ 99.0 mol%, Y ₂ O ₃ 0.5 mol%, Na ₂ O
A conventional voltage non-linear resistor element consisting of 0.5 mol% was left in an atmosphere of a temperature of 60 ° C. and a relative humidity of 95% RH, and the change with time of the dielectric loss was examined.

Next, the reason why the ratio of each component is limited will be described. Main component (Sr _1-xy Ba _x C a _y ) Ti
In O ₃ , the amount of Ba, that is, x is set to 0 <x ≦ 0.30
And the amount of Ca, that is, y was set to 0.25 or less,
This is because, as in Sample No. 7 and Sample Nos. 16 and 17, when x and y exceed these ranges, the surge withstand capability decreases, which is not preferable.

Further, Nb, W, T as a semiconducting agent
a, In or the amount of the rare earth element oxide is 0.1 to
The reason for setting the content to 2.0 mol% is that when these oxides are 0 mol% as in Sample No. 22, the varistor characteristics are not exhibited. Further, as in Sample No. 18, when the content of these oxides exceeds 2.0 mol%, the surge withstand capability decreases, which is not preferable.

In addition, CuO, Pb used as an oxidizing agent
O, Bi ₂ O ₃ , Sb ₂ O ₃ , V ₂ O ₅ , MoO ₃ at least one selected from the group consisting of Na _p M _{q Or} and the amount of the compound represented by Na _p M _{q Or} are less than 0.01 mol%. Otherwise, if one of the oxidizing agents is not included as in the sample numbers 30 and 43, the varistor voltage and the nonlinear coefficient become small, which is not preferable. Further, sample number 36,
As in 37, 48 and 49, these amounts are 2.0 mol%
This is because, when it exceeds, the surge withstand capacity decreases, which is not preferable.

On the other hand, when the grain boundary oxidation type voltage non-linear resistance composition of the present invention is used, the surge resistance after application of a surge current of 5000 A / cm ² is excellent, and the non-linear coefficient is α>
A high value of 15 can be obtained, and a voltage non-linear resistor having a small change over time in dielectric loss during high temperature and high humidity, that is, excellent in moisture resistance can be obtained. Further, since the capacitance is increased by adding Ba, Ba is added.
The capacitance can be controlled by the addition amount of.

[Brief description of the drawings]

FIG. 1 is a graph showing time-dependent changes in dielectric loss of a voltage nonlinear resistor using a grain boundary oxidation type voltage nonlinear resistor composition of the present invention and a conventional voltage nonlinear resistor composition at high temperature and high humidity. is there.

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yasunobu Yoneda 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. (72) Inventor Yukio Sakabe 2-26 Tenjin, Nagaokakyo-shi, Kyoto No. 10 Murata Manufacturing Co., Ltd. (56) References JP-A-2-180750 (JP, A) JP-A-3-45559 (JP, A) JP-A-58-91602 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 35/46

Claims (1)

(57) [Claims] (1) (Sr _1-xy Ba _x C a _y ) TiO
₃ (however, 0 <x ≦ 0.3 , y ≦ 0.25)
0 to 99.9 mol% and at least one oxide selected from Nb, W, Ta, In and rare earth elements in an amount of 0.1 to 2.0 mol%, and
_{O, PbO, Bi 2 O 3} , Sb 2 O 3, V 2 O 5, Mo
At least one selected from O ₃ and Na _p M _q O
_r (where M is at least one of Mo and W, p
= 2n, q = 2n ', r = n + 3n', where n and n 'are 1 or 2) in total of 0.01 to 2.0 mol%
A grain boundary oxidation type voltage non-linear resistance composition contained.