JPH01179301A - Voltage nonlinear resistor and surge-absorbing element using it - Google Patents

Abstract

PURPOSE:To obtain a high clipping voltage which can withstand a high test voltage prescribed by a law and to make a surge-absorbing element small-sized by using a voltage nonlinear resistor where zinc oxide as the main constitutent is mixed with silicon carbide for the surge-absorbing element. CONSTITUTION:A voltage nonlinear resistor 1 is constituted in the following manner: a mixture of metal oxides whose main constituent is zinc oxide is mixed with silicon carbide; a binder such as polyvinyl alcohol or the like is added to this mixture; this is pressed and molded like a disk shape; this molded disk is baked at a prescribed temperature to form a sintered body 2; a silver paste is applied to both faces of this body to form varistor electrodes 3, 3. During this process, the range of a mixture ratio of the metal oxides is set to be as follows: Bi2O3: 0.07-4.0mol%; CoO: 0.05-4.5mol%; MnO: 0.07-10.0mol%: Sb2O3: 0.05-6.0mol%. In this range, an excellent characteristic of a surge-absorbing element is displayed sufficiently.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a zinc oxide-based voltage non-linear resistor and a surge absorption element having a parallel connection structure of the voltage non-linear resistor and a discharge gap. In particular, the present invention relates to a voltage nonlinear resistor in which the varistor voltage is increased by mixing silicon carbide, and a surge absorption element that is miniaturized by using the same.

[Prior Art] Traditionally, in order to protect electronic circuit components from transient abnormal voltages applied to electronic equipment and surges caused by induced lightning, varistors made of voltage non-linear resistors and discharge gaps sealed in airtight containers have been used. Various surge absorbing elements such as arresters that utilize discharge phenomena are used, and the applicant has already developed a surge absorbing element in which a voltage nonlinear resistor and a discharge gap are connected in parallel and sealed in an airtight container. Proposal (JP-A-59-157981
> are doing.

The above-mentioned surge absorbing element has excellent surge absorbing characteristics that combine the coordination of a varistor and the large current withstand capability of an arrester. That is, when a surge equal to or higher than the clip voltage is applied to the surge absorbing element, a current immediately flows through the voltage nonlinear resistor to start surge absorption, and the voltage drop across the voltage nonlinear resistor due to this current increases to the discharge gap. When the discharge starting voltage is exceeded, arc discharge is formed in the discharge gap through glow discharge, thereby absorbing the large current surge.

[Problems to be Solved by the Invention] By the way, among electronic devices, devices subject to the Electrical Appliance and Material Control Law must undergo various tests stipulated by the above law, especially in the dielectric strength test. , a test voltage as high as 1O times the rated voltage is applied between the equipment line and ground. This high voltage is also applied to the above-mentioned surge absorbing element, which is connected between the line and the ground because of its large current withstand capability. Therefore, if the clip voltage of the surge absorbing element is lower than the test voltage, current will flow through the element and the electronic device will fail the test. Therefore, the clip voltage of the above surge absorption element is
It is necessary to set it to a value that exceeds the above test voltage.

The above clipping voltage is the varistor voltage V+ of the voltage nonlinear resistor (thickness 1 [mm] when the current is 1 [mA, ])
The above varistor voltage is determined by
1 is approximately proportional to the thickness of the voltage nonlinear resistor. Further, the voltage nonlinear resistor is usually formed by press molding, and its diameter needs to be larger than the thickness from the viewpoint of moldability.

However, when a sintered body obtained by adding bismuth oxide, cobal oxide, manganese oxide, and antimony oxide to zinc oxide is used as the voltage nonlinear resistor,
Although excellent voltage nonlinear characteristics can be obtained, the varistor voltage ■1 is as low as about 150 [V/mm], so in order to increase the clip voltage of the surge absorption element, a large voltage nonlinear resistor must be used. It is necessary to use it. For example, A
The dimensions of a voltage nonlinear resistor that does not conduct even when AClooO[V], which is the dielectric strength test voltage for electronic equipment rated CIoo[V], is applied are: thickness 10[mml, diameter 1
It will be about 0 [mm]. Therefore, there arises a problem that the material cost increases and the cost increases, and furthermore, the external size of the surge absorbing element incorporating this voltage nonlinear resistor becomes large.

The present invention has been devised in view of the above points, and by devising the composition of materials, it is possible to obtain a voltage nonlinear resistor that is small and has a high varistor voltage. The purpose is to realize a surge absorption element that has a high clipping voltage that can withstand the high test voltage required by law, and that can be provided compactly and inexpensively by incorporating it.

[Means for solving the problem] In order to achieve the above objectives, as a result of various studies, we decided to use a resistance material mainly composed of zinc oxide, which has excellent voltage nonlinear characteristics, and a voltage nonlinear resistance material with a high varistor voltage. By mixing silicon carbide, the voltage non-linear resistor of the present invention was completed, and further, by combining the voltage non-linear resistor and the discharge gap, the surge absorbing element of the present invention was completed. be.

Therefore, the voltage nonlinear resistor of the present invention has zinc oxide as a main component, to which oxides of bismuth, cobalt, manganese, and antimony are added to form a mixture, and the mixture and silicon carbide are The surge absorbing element of the present invention has a structure in which a sintered body is obtained by mixing the above-mentioned silicon carbide so that the content ratio is 0.01 to 80 mol%. , to which M(l) of bismuth, cobalt, manganese and antimony is added to form a mixture, and the mixture and silicon carbide are
The content ratio of the above silicon carbide is 0.01 to 80
A voltage non-linear resistor is mixed and sintered so as to have a mol%, and an electric current is connected to both ends of the voltage non-linear resistor to form a discharge gap between the electrodes, and the voltage non-linear resistor and the discharge gap are It has a configuration in which the two are connected in parallel and sealed in an airtight container.

[Operation] Since the present invention has the above-described configuration, the varistor voltage of the voltage nonlinear resistor becomes a high value due to the high varistor voltage of the mixed silicon carbide. Furthermore, since the varistor voltage of the voltage nonlinear resistor is high, a surge absorbing element with a high clipping voltage can be obtained even if a small-sized resistor is incorporated.

[Example] Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a sectional view of a voltage nonlinear resistor according to an embodiment of the present invention. In the figure, the voltage nonlinear resistor 1 is made of a mixture of metal oxides mainly consisting of zinc oxide (ZnO) and silicon carbide (SiC), and polyvinyl alcohol press molding is applied to this. The sintered body 2 is further fired at 1100 to 1400°C, and silver paste is applied to both surfaces of the sintered body 2 to form the varistor electrodes 3.3.

The above metal oxide mixture includes zinc oxide (ZnO)97.
8 mol%, bismuth oxide (Bi20z) 0.5 mol%
, cobalt oxide (Coo) 0.5 mol%, manganese oxide (MnO) 0.7 mol% and antimony oxide (Sb2
0i) 0.5 mol% is added, and the voltage non-linearity index α becomes maximum at this blending ratio. Note that a voltage nonlinear resistor that can be used in a surge absorption element having a parallel connection structure of a voltage nonlinear resistor and a discharge gap must have a voltage nonlinear index α of 30 or more, The blending ratio range of additives satisfying this condition is Bi203:
0.07-4.0 mol%, Coo: 0.

05-4.5 mol%, Mn. O: 0. 0 7~
1 0.

0 mol%, Sb203: 0.0 5-6.0 mol%
Within this range, the excellent characteristics of the surge absorbing element are fully exhibited.

Regarding the mixing of the metal oxide mixture containing ZnO as the main component and SiC, as shown in Fig. 2, SiC
As the mixing ratio increases, the varistor voltage V1 also increases, but the value of the voltage non-linearity index α decreases. For this reason, SiC
The mixing ratio with respect to the total amount of
Excellent surge absorption characteristics are obtained when the value is set in the range from 0.01 mol%, which is 00 [Vl, to 80 mol%, where α maintains a value of 30 or more.

FIG. 3 is a sectional view showing a surge absorbing element incorporating the voltage nonlinear resistor described above. In the figure, the surge absorbing element 4 has electrodes 6 attached to both ends of the voltage nonlinear resistor (2) using conductive adhesives 5,5.

6 are connected so that the peripheral edges of the electrodes 6.6 are facing each other, and the electrodes 6.6 are discharged with a discharge gas appropriately selected from rare gases (He, Ne, Ar, etc.), inert gases such as nitrogen gas, sulfur hexafluoride gas, etc. It has a structure in which it is sealed together with gas in an airtight container 7 and external terminals 8.8 are led out.

In this state, a discharge gap 9 is formed in the opposing portions of the electrodes 6, 6, and is electrically connected in parallel with the voltage nonlinear resistor 1.

Therefore, when a surge equal to or higher than the clip voltage is applied to the surge absorbing element 4 of the present invention, the voltage nonlinear resistor 1 is immediately
A surge current flows through the voltage non-linear resistor 1 and surge absorption is started, and a voltage drop corresponding to the product of the current value of this surge current and the resistance value of the voltage non-linear resistor 1 occurs between both ends of the voltage non-linear resistor 1.

As the number of current ports increases, this voltage drop also increases, and when this exceeds the discharge starting voltage between the electrodes 6, 6, an excited discharge is generated in the discharge gap 9, and its energization instantly causes the electrode 6 to .6 to form a main discharge that conducts a large current, thereby absorbing large current surges.

[Effects of the Invention] As detailed above, the voltage nonlinear resistor of the present invention is formed by mixing a material mainly composed of Zr and O, which has excellent voltage nonlinear characteristics, and SiC, which has a high varistor voltage. Therefore, it is possible to obtain a high varistor voltage with a small size without significantly deteriorating the nonlinear characteristics, and furthermore, it is possible to reduce costs by reducing the amount of materials used. In addition, since the surge absorbing element of the present invention incorporates the voltage nonlinear resistor with a high varistor voltage, a high clipping voltage that exceeds the test voltage specified by law can be easily achieved even when using a voltage nonlinear resistor with small dimensions. It can be obtained in a small size, and can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a voltage nonlinear resistor according to the present invention, and FIG.
The figure is a graph showing voltage nonlinear characteristics and varistor voltage characteristics with respect to silicon carbide content, and FIG. 3 is a cross-sectional view of a surge absorbing element according to the present invention. 1... Voltage nonlinear resistor, 2... Sintered body, 4...
Surge absorption element, 6.6... Electrode, 7... Airtight container, 9... Discharge gap. Patent applicant: Okaya Electric Industry Co., Ltd.

Claims (4)

[Claims] (1) Zinc oxide is the main component, to which oxides of bismuth, cobalt, manganese and antimony are added to form a mixture, and the mixture and silicon carbide are mixed so that the content ratio of the silicon carbide is 0. .01 to 80 mol % of the voltage nonlinear resistor, characterized in that it is mixed to form a sintered body. (2) The content ratio of bismuth, cobalt, manganese and antimony oxides in the mixture mainly composed of zinc oxide is 0.07 to 4.0 mol% and 0.05 to 4.5 mol%, respectively. , 0.07 to 10.0 mol% and 0.07 to 10.0 mol%.
The voltage nonlinear resistor according to claim 1, characterized in that the content of the nonlinear voltage resistor is 0.05 to 6.0 mol%. (3) A mixture containing zinc oxide as the main component, to which oxides of bismuth, cobalt, manganese and antimony are added, and the mixture and silicon carbide are mixed so that the content ratio of the silicon carbide is 0. Electrodes are connected to both ends of the voltage non-linear resistor to form a sintered body and a discharge gap is formed between the electrodes, and the voltage non-linear resistor and the discharge 1. A surge absorbing element characterized by being sealed in an airtight container with gaps connected in parallel. (4) The content ratio of bismuth, cobalt, manganese and antimony oxides in the mixture mainly composed of zinc oxide is 0.07 to 4.0 mol% and 0.05 to 4.5 mol%, respectively. , 0.07 to 10.0 mol% and 0.07 to 10.0 mol%.
The surge absorbing element according to claim 3, wherein the content is 0.05 to 6.0 mol%.