JPH0377293A - Electrode material for shock absorber and surge absorber using the same material - Google Patents

Abstract

PURPOSE:To increase the lifetime of an electrode material as a surge absorber by jointing copper or copper alloy to at least one side of low thermal expansion alloy like covar or iron-nickel alloy, and making the thickness of the copper or the like equal to or less than the specific percentage of the total thickness of a composite material. CONSTITUTION:Copper or copper alloy is jointed to at least one side of low thermal expansion alloy like covar or iron-nickel alloy and the thickness of the copper or copper alloy is made equal to or less than 40% of the total thickness of a composite material. This composite material is used at both sides of a gas sealed ceramic insulation tube, and the surface of the copper or copper alloy is so made as to form a discharge surface for the formation of a discharge electrode as a surge absorber. In this case, the composite material 2A is so press molded as to be suitable for coupling to the ceramic insulation tube 1, and formed as a composite material discharge electrode 2. In addition, the material 2A and the tube 1 filled with gas 4 are combined with each other so that the copper or copper alloy 2b becomes an opposite discharge surface, and then brazed. According to this construction, the lifetime of an electrode material as a surge absorber can be remarkably improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a device installed in a protector, etc. at the subscriber end of a communication line, to prevent lightning damage caused by lightning strikes. The present invention relates to an electrode material useful for use in surge absorbers and a novel surge absorber using the same.

[Prior Art] In recent years, semiconductors such as LSIs have been widely used in low-voltage equipment and information equipment connected to communication lines.
Although the bassage voltage itself is small compared to direct lightning strikes, the influence of induced lightning, which occurs more frequently every week, has emerged as an important issue.

This induced lightning surge is induced on a communication line by the electromagnetic field of a lightning discharge current that strikes near the line.
This is caused by the following phenomena.

In other words, when a lightning discharge occurs between a thundercloud and the ground, an electromagnetic field is generated in space and propagates over a long distance.At this time, because the conductivity of the ground is finite, the electric field is tilted slightly in the direction of travel. , an electric field component perpendicular to the earth and an electric field component horizontal to the earth appear.

The horizontal electric field component acts as an electromotive force in the longitudinal direction of the cable core and metal sheath, while the vertical electric field component is applied as an electromotive force between the cable core and the ground, propagates to the line terminal, and causes lightning surges. to occur. This lightning surge is
At the subscriber terminal, the voltage becomes a core-to-ground voltage and is applied to the equipment. Therefore, it is necessary to take appropriate measures to protect equipment from lightning damage and to minimize damage.

What is shown in FIG. 4 is a sketch having a half cross section showing an example of a surge absorber generally used as a measure to prevent such lightning damage, and FIG. 5 is a side view thereof.

Specifically, discharge electrodes 2-. 2- are placed opposite to each other, and one is connected to the communication line and the other to the grounding wire via the lead terminal 3.3 (neither is shown in the figure), and the above-mentioned lightning surge is connected to the electric power w12-. ．． This is to prevent devices such as telephones from being damaged by surge voltage by discharging the voltage between 1' and 1'.

[Problems to be Solved by the Invention] The above-mentioned surge absorber is required to be a nonflammable material due to its intended use, and ceramic is generally used as the insulating tube.

As the discharge electrode 2, Kovar (29%Ni-17%CO-54%Fe alloy) has an implicit tensile coefficient close to that of ceramic.
are used, and these ceramic tube 1 and discharge electrode 2
When joining and sealing the two parts using silver brazing or the like, the soldering is done in such a way that there is no mismatch in thermal expansion between the two parts.

That is, if a mismatch in thermal expansion occurs during this soldering, microcracks will gradually occur at the soldered portion between the ceramic 1 and the electrode 2 over time, and the filled gas 4 will escape without realizing it. This causes so-called slow leakage, which causes deterioration of discharge characteristics.

Although the above-mentioned Kovar has excellent properties in matching the thermal Wfj tension with such ceramics, it cannot necessarily be said that there are no problems from the viewpoint of a discharge electrode material. The disadvantage of the pole is that the discharge surface is easily damaged during repeated surge discharges, and there is a strong possibility that the discharge characteristics will change during use.

Furthermore, Kovar is an expensive material and has the problem of not being compatible with demands for cost reduction.

It is an object of the present invention to provide a surge absorber that solves the problems of the prior art as described above, has a longer service life in repeated surge discharges, and achieves overall cost reduction. The present invention aims to provide an electrode material and a surge absorber using the same.

[Means for Solving 5U1] The present invention is a Ti material for a surge absorber, in which copper or a copper alloy is bonded to at least one side of a low thermal expansion alloy such as Kovar or an iron-nickel alloy. The composite material is used on both sides of a ceramic insulating tube filled with gas, and the copper or copper alloy surface is the discharge surface. The discharge electrode is formed in such a manner that it is configured as a surge absorber.

[Effect 1] The applicant's various experiments have demonstrated that copper has excellent discharge characteristics and is not significantly damaged by repeated discharges.

Therefore, by using copper or copper alloy for the discharge surface, the life of the surge absorber can be dramatically improved, and by using a composite material of low-temperature WJ alloy, the problem of slow leakage can be solved. It is also possible to reduce costs by using .

[Example] The present invention will be described below with reference to Examples.

FIG. 3 is an explanatory cross-sectional view that does not show the cross-sectional structure of the composite material 2A used as the electrode material of the surge absorber according to the present invention.

In the figure, 2a is a low thermal expansion alloy, which is not limited to the above-mentioned Kovar, but may also include equivalent Fe-Ni alloys such as Invar (Fe-36%Ni alloy) containing 32 to 50% by weight of Ni. Materials having a coefficient of linear expansion can be used.

2b is copper or a copper alloy, and in the case of a copper alloy, the total amount of added elements is preferably 10% by weight or less in order to suppress an increase in electrical resistance and maintain the original discharge characteristics of copper.

In addition, the copper or copper alloy layer 2b may be provided on one side of the low-temperature zero-strength alloy 2a from the viewpoint of its intended use, but considering the forming balance during processing, it may be provided on both sides. be.

Such a copper or copper alloy layer 2b can be easily formed by a hot or cold cladding method, but it can also be formed by a simple method such as a plating method.

In this case, the thickness of the copper or copper alloy NJ2b is determined from the viewpoint of maintaining thermal expansion matching during soldering with the ceramic insulating tube mentioned above and preventing slow leakage of the filled gas. 40% of the plate thickness
It is necessary to have the following plate thickness.

FIG. 1 is a half-sectional diagram showing an embodiment of a surge absorber according to the present invention using the electrode material according to the present invention constructed as described above, and FIG. 2 is a side view thereof. be.

In the present invention, the composite material 2A is press-molded to form a composite discharge electrode 2 so as to fit snugly into a ceramic insulating tube 1, and a gas 4 is sealed inside as shown in the figure. The copper or copper alloy surfaces 2b are assembled and soldered together to form opposing discharge surfaces. 3 is already the 4th
and the lead terminal explained in FIG.

With the above configuration, copper or copper alloy 2b, which has better discharge characteristics than Kovar, is disposed on the discharge surface of the discharge electrode 2.2, which makes it possible to eliminate the problems seen in the case of conventional Kovar single material. , the drawback that repeated surges cause roughness on the discharge surface and shorten the surge cycle life.
Significant improvements can be made. As a result, the service life of the surge absorber can be significantly improved.

In addition, when the discharge electrode 2 and the ceramic insulating tube 1 are soldered with silver solder, the soldering surface of the discharge @ Th' [i becomes copper or copper alloy, so that the soldering column is improved.1. It is also possible to bring out the secondary advantage of further improving reliability against slow rolling.

[Effects of the Invention] As described above, according to the electrode material according to the present invention and the surge absorber using the same, the life of the surge absorber can be significantly improved, and an overall inexpensive and highly reliable device can be provided. This makes it possible to respond appropriately to contemporary demands.

[Brief explanation of drawings]

FIG. 1 is a sketch with a half cross section showing an embodiment of the surge absorber according to the present invention, FIG. 2 is a side view thereof, and FIG. 3 is an explanatory sectional view showing the structure of the electrode material used in the present invention. FIG. 4 is a sketch with a half cross section showing a conventional surge absorber, and FIG. 5 is a surface survey thereof. 1: Ceramic insulating tube, 2: Composite discharge electrode, 2A: Composite material, 2a: Low thermal expansion alloy, 2b: Copper or copper alloy, 3: Lead terminal, 4: Enclosed gas.

Claims (2)

[Claims] (1) Surge made by bonding copper or copper alloy to at least one side of a low thermal expansion alloy such as Kovar or iron-nickel alloy, and making the plate thickness of the copper or copper alloy less than 40% of the total plate thickness of the composite material. Electrode material for absorber. (2) A surge absorber in which the electrode material according to claim 1 is installed as a discharge electrode at both ends of a ceramic insulating tube in which a gas is sealed, and the copper or copper alloy surface is arranged as the opposing discharge surface.