JPH0282503A - Voltage nonlinear 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 (Field of Industrial Application) The present invention relates to a voltage nonlinear resistance element made of a metal oxide.

(Prior Art) Conventionally, among voltage nonlinear resistance elements made of metal oxides, voltage nonlinear resistance elements mainly composed of zinc oxide have excellent nonlinear voltage-current characteristics comparable to Zener diodes.
Because it has high withstand current characteristics, it has been widely used for voltage stabilization, pulse voltage suppression, surge voltage absorption, and lightning arrester applications. FIG. 2 shows a voltage nonlinear resistance element mainly composed of zinc oxide inserted into a conventional linear lead wire. In the figure, 1 is a voltage nonlinear resistance element, 2 is an electrode, and 3 is a lead wire. An evaluation test for the voltage non-linear resistance element 1 whose main component is zinc oxide includes surge current withstand capacity.

This test was performed using an f of 8120 μs specified by JEC.
i? (This is evaluated by the rate of change in varistor voltage when the II waveform is applied. The smaller this rate of change is, the better the surge current withstand capacity is. In order to improve this surge current withstand capacity, various additives are used. A lot of research has been carried out, such as examining the material and making the crystal grain size uniform.

(Problem to be Solved by the Invention) However, when the device was investigated after a surge current withstand test, it was found that the rate of change in varistor voltage at the contact area between the positive lead wire and the electrode and the surrounding area was lower than that of other devices. The result was that it was significantly larger.

This is because when a surge current is applied, the conventional linear lead wire 3 as shown in FIG. Can not. This is because the current is concentrated in and around the contact area between the lead wire 3 and the electrode 2.

That is, in order to improve the surge current withstand capacity, it is necessary to prevent this local concentration of current and to make the current density uniform.

SUMMARY OF THE INVENTION An object of the present invention is to provide a voltage nonlinear resistance element that solves the conventional problems, prevents current concentration that occurs at the contact portion between a lead wire and an electrode, and makes the current density uniform.

(Means for Solving the Problems) The voltage nonlinear resistance element of the present invention has a contact portion between an electrode formed on both pole surfaces of a voltage nonlinear resistance element made of a metal oxide and an extraction lead wire, and a shape of the lead wire. However, in the positive direction, it is disk-like or mesh-like, and in the negative direction, it is linear.

(Function) With the above configuration, it is possible to prevent current concentration that occurs at the contact portion between the conventional lead wire and the electrode, and to equalize the current density.

(Example) An embodiment of the present invention will be described based on FIG.

FIG. 1 shows a voltage nonlinear resistance element whose main component is zinc oxide and which is inserted into a lead wire according to the present invention. In this figure, the same parts as those in the conventional example shown in FIG. 2 are given the same reference numerals, and the explanation thereof will be omitted.

A sintered body is produced through processes such as mixing, granulating, molding, and firing powder containing zinc oxide as a main component, and silver counter electrodes 2 are formed on both poles of this element and fired. In this way, the element diameter was 20+m, the element thickness was 1.0mm, and the electrode diameter was 17nm.
w, a voltage nonlinear resistance element 1 with a varistor voltage V1mA=100V is created. The lead wire 3 is soldered in advance. Lead wires 3 are inserted into the element soaked in flux, and dipped in eutectic point solder at 230 to 240°C. After dipping, the flux is washed and removed with an organic solvent, resulting in a sample as shown in FIGS. 1(a) and 1(b).

However, in the figure, it is shown in the form before the solder dip. However, if a surge current withstand test is performed as is, creeping discharge will occur, so the test is performed by coating it with epoxy resin.

A standard waveform current of 312011s of 8000 A was applied twice at 5 minute intervals to the sample prepared as described above.

Look at the rate of change in varistor voltage. The results are shown in the table.

Shape of lead wires and surge/current resistance (effects of the invention) According to the present invention, the contact area between the lead wires and the electrodes is widened, thereby preventing local current concentration.

The current density can be made uniform, and as a result, the surge current withstand capability can be improved, which has a great practical effect.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a voltage non-linear resistance element according to an embodiment of the present invention, and FIG. 2 is a plan view of a conventional voltage non-linear resistance element. 1... Voltage nonlinear resistance element, 2... Electrode, 3...
·Lead. Patent applicant: Matsushita Electric Industrial Co., Ltd. (n = 10) As can be seen from the table, the present invention reduces the rate of change in varistor voltage. (a) Figure ■ (b) Figure

Claims (1)

[Claims] At the contact portion between the electrodes formed on both pole surfaces of a voltage nonlinear resistance element made of metal oxide and the lead wire, the shape of the lead wire is disk-like or mesh-like in the positive direction, and linear in the negative direction. A voltage nonlinear resistance element characterized by: