JPH0347282Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical Field of the Invention] The present invention relates to a high power varistor with an improved heat sink structure that significantly improves heat dissipation. [Technical background of the invention and its problems] In general, high-power varistors need to have good heat dissipation, so conventionally the outer periphery was left on the plate-shaped varistor body made by molding and sintering ceramic powder. An electrode plate was soldered to the silver electrode formed by the process, and the electrode plate exerted a heat dissipation function. However, as a technique that has been proposed for this purpose, for example,
There is a publication. In other words, the technique disclosed in the publication includes an electrode that also serves as a heat sink on one electrode 22 of a varistor body 23 in which an electrode 22 is formed leaving an outer peripheral edge 21 on both the front and back surfaces, as shown in FIGS. 7 and 8. The plate 24 is constructed by soldering lead wires 25 to the other electrode 22 and applying an exterior resin (not shown). However, the technique disclosed in this publication has the following drawbacks. That is, the lead wire 2 connected to the other electrode 22
No. 5 has a small heat absorption effect, so the heat dissipation effect is not sufficient, and since the plane of the mounting part of the varistor body 23 of the electrode plate 24 is larger than the diameter of the electrode 22, if the solder protrudes from the electrode 22 part during soldering, the above-mentioned A solder layer 2 is placed in the gap between the outer peripheral edge 21 and the electrode plate 24.
6, which makes no sense in providing the outer peripheral edge 21, and in the end, the insulation is insufficient and causes creeping discharge to occur.Furthermore, since the electrode drawn out from the other electrode 22 is the lead wire 25, When used in places with strong vibrations, such as in automobiles, there were many problems that needed to be resolved, including the risk of wire breakage due to the inability to withstand continuous vibrations. [Purpose of the invention] The present invention was made in view of the above points, and it solves the above problems, eliminates the risk of creeping discharge, and greatly improves the heat dissipation effect, and can exhibit stable characteristics for a long time. The purpose is to provide a high power varistor. [Summary of the invention] The high-power varistor of the present invention has an electrode formed on both sides of a plate-shaped varistor body leaving an outer periphery, and an electrode mounting part with a diameter smaller than the electrode area and an arbitrary part of the mounting part. The external connection parts of the electrode terminal are integrally molded with the external connection parts protruding from the parts, and the external connection parts are led out in the same direction without overlapping each other, one side of the electrode attachment part is soldered, and an exterior resin is applied. It is characterized by: [Embodiment of the invention] An embodiment of the invention will be described below with reference to the drawings. That is, as shown in FIGS. 1 and 2, the main ingredients are zinc oxide, tin oxide, barium titanate, strontium titanate, etc.
In addition, a plate-shaped varistor body 1 is formed by molding and sintering ceramic powder mixed with several kinds of metal oxides into a disc shape, leaving an outer periphery 2 on both sides, and applying and baking, for example, a silver paste to form an electrode 3. As shown in FIG. 3, an electrode mounting portion 4 having a diameter smaller than the area of the electrode 3 and an external connection portion 5 protruding from an arbitrary location around the electrode mounting portion 4 are integrally molded on the electrode 3. For example, the external connection portion 5 of the varistor element body 1 is brought into contact with one side of the electrode mounting portion 4 of an electrode terminal 6 made of copper, aluminum, iron, or an alloy thereof, which has been subjected to solder plating, tin plating, or nickel plating.
Both sides are led out in the same direction without overlapping each other and connected via solder 7, and then a resin dip coat is applied to form an exterior resin 8. According to the high power varistor configured as described above, since the electrode terminals 6 which also serve as heat sinks are attached to the electrodes 3 on both sides of the varistor body 1, energy absorption is large, and heat is absorbed from both sides of the varistor body 1. This makes it possible to improve the heat dissipation effect, and since the mounting part of the electrode terminal 6 has a smaller diameter than the area of the electrode 3, the solder 7 does not protrude to areas other than the electrode 3, eliminating the risk of creeping discharge. Since the connecting parts 5 are introduced in the same direction without overlapping each other, the fluidity of the coating resin at the outlet part is extremely good, and it is possible to easily obtain an excellent exterior resin 8. Further, since both electrode terminals 4 are made of metal plates, there are many advantages such as there is no risk of wire breakage even under conditions of severe vibration. Next, a comparison of characteristics between the present invention shown in FIGS. 1 and 2 and the conventional reference example shown in FIGS. 5 and 6 will be described based on experimental results. i.e. diameter 13.5
mm, thickness 2.5mm molded and sintered rise voltage (V1m
A) This invention (A) in which silver electrodes with a diameter of 11.4 mm are formed on both sides of a zinc oxide-based varistor element set at 470 V, and the H dimension shown in Figure 3 is 11.0 mm, and the H dimension shown in Figure 6 Figure 4 and Table 1 show the results of examining the rate of change in the number of square wave energy applications - V1mA and the dielectric breakdown due to creeping discharge compared to the conventional reference example (B) with dimensions of 13.5 mm. The electrode terminal is (A)
Both (B) are solder-plated with iron-nickel alloy. In addition, the number of applications in Figure 4 is when 20 msec square wave energy 200 Jule is applied once for 5 minutes, and the test conditions in Table 1 are 2500 A (1 x 40 μsec
Standard waveform) Impulse is applied 10 times. There are 20 samples each.

[Table] As is clear from Figure 4 and Table 1, reference example (B)
The rate of change in V1mA is large, the heat dissipation is poor, and there are many dielectric breakdown failures due to creeping discharge, whereas
The product of this invention (A) has V1mA even after 30 applications.
The heat dissipation property was good, with a rate of change of about -5%, and there was no dielectric breakdown failure due to creeping discharge, demonstrating an excellent effect. [Effects of the invention] According to the invention, it is possible to obtain a high-power varistor that has a high heat dissipation effect, has no risk of creeping discharge, maintains stable characteristics for a long time, and has high practical value.

[Brief explanation of the drawing]

1 and 2 show a high power varistor according to an embodiment of the present invention, in which FIG. 1 is a plan view, FIG. 2 is a sectional view taken along the line E--E in FIG. and a perspective view showing the electrode terminals constituting FIG.
The figure shows a change rate characteristic curve of the number of square wave energy applications - V1mA, and Figures 5 and 6 show a high power varistor according to a conventional reference example. Figure 5 is a plan view, and Figure 6 is a It is a sectional view of the figure Rollo. DESCRIPTION OF SYMBOLS 1... Varistor element body, 2... Outer periphery, 3... Electrode, 4... Electrode mounting part, 5... External connection part, 6...
...Electrode terminal, 7...Solder, 8...Exterior resin.

Claims (1)

[Scope of utility model registration request] A plate-shaped varistor element formed by molding and sintering a metal oxide, an electrode formed with outer peripheral edges left on both sides of the element, and an electrode attached to the electrode with a smaller diameter than the electrode area through solder. and an electrode terminal consisting of an external connection part protruding from an arbitrary part of the mounting part and leading out in the same direction without overlapping each other, and an exterior resin covering the varistor element. Barista.