JPS6239001A - Voltage non-linear resistance element - 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] [Technical field to which the invention pertains]

The present invention relates to a voltage nonlinear resistance element that is made of porcelain that is mainly made of zinc oxide and that obtains voltage nonlinear resistance characteristics by itself.

[Prior art and its problems]

Voltage non-linear resistance elements mainly made of zinc oxide are known as ZnO with Co+Pr, K, Cr, etc. added, or Bi+Sb+Co, Cr, etc. added, and both are made using ordinary ceramic technology. The resistor is molded into a disc-shaped resistor using silver paste, an electric bridge is formed using silver paste, etc., the lead wires are soldered, and the resistor is coated with resin, and then sold on the market. However, in such a resistance element, leakage current occurs on the surface of the resistor after the lead wire is attached, resulting in deterioration of the nonlinear characteristics in the low current region.
Manufacturers have had problems with reduced yields, and users have had problems with malfunctions after installation. Countermeasures have been taken to counter this problem, such as increasing the surface resistance by co-firing a glass coating on the surface of the resistor, which is formed in a disc shape, or providing a residual film on the resistor surface.
Both methods have the disadvantage of significantly increasing costs. Another problem is that when polishing the surface of a voltage nonlinear resistor, the side surfaces are likely to be worn away, so it is desired that the surface hardness of the resistor be even higher.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a voltage nonlinear resistance element that improves the insulation characteristics of the surface of a resistor and increases the surface hardness without significantly increasing cost.

[Key points of the invention]

According to the present invention, the voltage nonlinear resistance element is mainly made of zinc oxide and contains at least a lanthanum-based rare earth element (L a +
C'e + P r + N d 1S-1τb, D
y) and silicon, and this resistor has a lanthanum-based rare earth element on its surface.
When expressed as n, 'bnxos ・SiOx,
LntOx H25ift or 2Lng03 ・
The above object is achieved by the presence of precipitated acicular crystals of the composite silicate compound of 3.

[Embodiments of the invention]

Example 1: Zinc oxide is used as the main raw material, and 1.5 at.% of Cr is added to it. 0.065 atomic% Pr+0.2 atomic%, 0.2 atomic%
of Cr and further added 100 at.
This was baked at 1300°C for 1 hour. Figure 1 is a metallurgical micrograph of the surface of this fired body, which shows acicular crystals that are not seen in the second factor, which is a metallographic micrograph of the surface of a conventional zinc oxide voltage non-direct & I resistor without Si added. Precipitation is shown. When this needle crystal was analyzed by scanning electron microscopy and X&1 diffraction, it was found that Prtys S10. It turned out to be a complex silicate compound represented by It was found that the surface on which the acicular crystals were deposited exhibited higher surface resistance and hardness, as shown in Table 1, than the surface without Si added. No decrease in voltage nonlinear resistance characteristics was observed. Table 1 Example 2: Using zinc oxide as raw material, Bib, 5 at%, sbo, s
% of Go, 1.0 atomic% of Go, 0.5 atomic% of Cr, and 100 atomic ppm each of Pr and Si were added, fired in the same manner as in Example 1, and the surface was observed, as shown in Figure 1. Pr103 ・S similar to Example 1 shown
Precipitation of acicular compounds of to was confirmed, and a voltage non-linear resistor comparable to the conventional one which does not contain Pr or SL was obtained. In both Examples 1 and 2, it was recognized that if the firing temperature was increased, the surface resistance value and li! degree would further increase.
If the temperature exceeds 1350°C, the original performance as a voltage non-linear resistor will be significantly degraded and it cannot be put to practical use. Furthermore, if the amount of St added is less than 80 atomic ppm, the generation of needle crystals is small and no surface modification effect is observed, while if it exceeds 500 atomic pps+, the performance as a voltage nonlinear resistor will deteriorate. In the example, Pr was used as the lanthanum-based rare earth element, but it was confirmed that similar effects could be obtained when other earthwork M oxides were included. [Effects of the Invention] The present invention forms a surface layer with high electrical resistance and mechanical strength by adding a lanthanum-based rare earth element and silicon to the raw material itself in a voltage nonlinear resistor mainly made of zinc oxide. As a result, we were able to provide the market with a highly reliable zinc oxide voltage nonlinear resistance element that does not suffer from deterioration of nonlinear characteristics due to surface leakage current and does not suffer from wear on the sides during surface polishing, with almost no increase in cost. .

[Brief explanation of the drawing]

FIG. 1 is a surface micrograph of a resistor according to an embodiment of the present invention.
FIG. 2 is a surface micrograph of a conventional resistor. 11th Sword Proceedings Amendment Case December 26, 1985 Director-General of the Patent Office t1 Co., Ltd.], Incident Display Sakaki Sho ω-/7. pQ', gp3, relationship with the case of the person making the amendment Applicant's Embassy Name: 1-1 Tanabe Shinden, Kawasaki-ku, Kawasaki City
Name: +5231 Fuji Electric Co., Ltd. (other names) 4. Agent Address: 1-1 Tanabe Shinden, Kawasaki-ku, Kawasaki City Specification No. 6
"Surface micrograph of resistor" on the 4th and 5th lines of the page
The text has been corrected to read, ``Microphotograph showing the metal structure of a resistor.''

Claims (1)

[Scope of Claims] 1) A voltage nonlinear resistance element characterized by having a resistor formed by firing a raw material mainly composed of zinc oxide and containing at least one lanthanum-based rare earth element and silicon. 2) In the device according to claim 1, the amount of silicon added to the raw material is 80 atomic ppm or more and 500 atomic ppm.
A voltage nonlinear resistance element characterized in that the voltage is less than or equal to m.