JPH0352201A - voltage nonlinear resistor - Google Patents

Abstract

PURPOSE:To produce varistors having a good discharge voltage characteristic with less variation in varistor voltage by adding a specified amount of tin in the form of Bi2Sn3O9. CONSTITUTION:With zinc oxide as a main component, tin of 0.01 to 1.00mol% in Bi2Sn3O9 is added to this main component as a component. When the quantity of added Bi2Sn3O9 is less than 0.01mol%, a change rate of a permissible surge current becomes large, while alpha and a discharge voltage ratio turns inferior when the quantity is more than 1.00mol%. No reaction of SnO2 with Bi2O3 occurs in a process of a sintering reaction and a pyroclore phase is to be formed. According to this constitution, varistors having a good discharge voltage characteristic can be obtained with less variation in varistor voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a voltage nonlinear resistor used for stabilizing circuit voltage and absorbing surges and noise in various electronic devices.

BACKGROUND OF THE INVENTION Voltage nonlinear resistors are generally called varistors and are widely used for voltage stabilization, surge absorption, and the like. As a typical example, a varistor whose main component is zinc oxide (ZnO) is known. This ZnO varistor has characteristics such as good voltage nonlinearity and large surge current withstand capacity. The manufacturing method is zno(:R bismuth (8 120m).Cobalt oxide (CO203)
．． Manganese oxide (MnO+). # antimony (S
Add a small amount of b203), etc., mix uniformly, and after molding 1
It is sintered at a temperature of 000°C to 1400°C, and an electrode is provided on the sintered body. In such ZnO varistors, tin oxide (Sn02) is generally used as an additive in order to improve nonlinearity and surge current resistance.

Problems to be Solved by the Invention However, in this conventional configuration, since tin is added in the form of tin oxide, SnO is added during the sintering reaction process.
2 and Bi20g react from around 700℃, B+25n
lOg was being produced. Therefore, the formation of the pyrochlore phase, which is an important intermediate product of ZnO varistors, has been hindered. As a result, abnormal grain growth of Zn○ is likely to occur, and the variation in varistor voltage becomes large.
The problem was that the limiting voltage characteristics deteriorated.

The present invention solves the above-mentioned conventional problems, and aims to provide a voltage nonlinear resistor with small variations in varistor voltage and excellent limiting voltage characteristics.

Means for Solving the Problems To achieve this object, the voltage nonlinear resistor of the present invention is manufactured by using tin in the form of Bi2 SnmO*.
．． 00 mol% is added.

Function: With this configuration, SnO2 and BI are combined in the sintering reaction process.
There is no reaction of zOa, a pyrochlore phase is formed, and variations in varistor voltage are reduced, making it possible to provide a voltage nonlinear resistor with excellent limiting voltage characteristics.

EXAMPLES Hereinafter, the present invention will be explained in detail based on examples. First, ZnO, 8 120B, CO201+MnOz,
Each raw material of SbtOs, Sn02, and B{2SnsOi was prepared in the ratio shown in Table 1 below.

Next, after wet mixing the prepared raw materials, a binder was added and granulation was performed. Next, after molding this granulated powder, 1
Fired at 250°C, with a diameter of 10mm. A sintered body with a thickness of 1 mm was obtained. An A[J electrode was formed on this sintered body and used as a sample. Then, for each sample, each 50 varistor voltages (v1
．． A/Iml) measurement, its average and dispersion (δ.

-1) are also shown in Table 1. The voltage nonlinear coefficient (a), limiting voltage ratio (V2!IA/Vl-A), and surge current withstand capacity (rate of change in v 1 mA after application of current of 8/20 μS, 250 OA) are also shown. In addition, sample numbers 4 to 6 in Table 1 are according to the present invention.

(Margins below) Figures 1 and 2 show microscopic photographs of the grain structures of the sintered bodies of sample numbers 5 and 2 in Table 1. From FIGS. 1 and 2, it is clear that the product of the present invention (FIG. 1) has almost no abnormal grain growth.

As is clear from Table 1, when tin is added in the form of B12snsOi and 0.01 to 1.00 mol% is added, the v1. The variation in A/Iul is reduced. Furthermore, the limiting voltage ratio is also excellent.

However, B i2Sn. o. The amount added is 0.01 mol%
If it is less, the rate of change in the surge current withstand capacity will increase, and if it is more than 1.00 mol %, α and the limiting voltage ratio will deteriorate, both of which are not preferable.

Effects of the Invention As described above, the present invention improves SnOz in the sintering reaction process by adding tin in the form of Bl,,Sna○9.
The reaction between Bi203 and Bi203 does not occur, and a pyrochlore phase is formed, resulting in less variation in varistor voltage and excellent limiting voltage characteristics.

[Brief explanation of drawings]

FIGS. 1 and 2 are microscopic photographs of the grain structures of the sintered bodies of the product of the present invention and the conventional product.

Claims (1)

[Claims] The main component is zinc oxide, and tin is added to this main component.
A voltage nonlinear resistor characterized in that it is added in an amount of 0.01 to 1.00 mol% in terms of i_2Sn_3O_9.