JPH0316252Y2 - - 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, and for this reason, conventionally, ceramic powder was molded and sintered to leave an outer periphery on the plate-shaped varistor body. 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. 6 and 7. 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 has been 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 exhibits 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 portion with a diameter smaller than the area of the electrode and the mounting portion on one side of the electrode. One side of the electrode attachment part of a first electrode terminal integrally molded with an external connection part protruding from any part of the electrode is soldered, and an electrode attachment part with a diameter smaller than the area of the electrode and an electrode attachment part of the attachment part are soldered to the other side of the electrode. One side of the electrode attachment part of a second electrode terminal is integrally molded with an external connection part whose part protruding from an arbitrary part is a twisted part and the tip part is perpendicular to the attachment part, and the two electrode terminals are connected to each other by soldering. It is characterized in that the external connection parts are led out in the same direction without overlapping each other and are coated with exterior resin. [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. . For example, copper, aluminum, or aluminum plated with solder plating, tin plating, or nickel plating, etc., are integrally molded with the external connection part 6.
First electrode terminal 7 made of iron or its alloy, etc.
One side of the electrode attachment part 5 is attached to the electrodes 3 and 4.
As shown in FIG. 4, the other electrode 4 has an electrode attachment part 8 having a diameter smaller than the area of the electrode 4, and a part protruding from an arbitrary point around the attachment part 8 is a twisted part 9, and the tip part is attached to the attachment part 8. The first electrode terminal 7 is integrally molded with an external connection portion 10 having a shape perpendicular to the first electrode terminal 7.
one side of the electrode attachment part 8 of the second electrode terminal 11 made of the same material as that of the second electrode terminal 11 is attached to each other, and the external connection parts 5 and 10 are led out in the same direction without overlapping and connected via solder 12, Thereafter, a resin dip coating is applied to form an exterior resin 13. According to the high-power varistor configured as described above, the electrodes 3 and 4 on both sides of the varistor body 1 have the first electrode terminal 7 and the second electrode terminal 11 which also serve as heat sinks.
Since the mounting portions 5 and 8 of the first electrode terminal 7 and the second electrode terminal 11 are attached, the amount of energy absorbed is large, and heat can be absorbed from both sides of the varistor body 1, which improves the heat dissipation effect accordingly. Since the diameter is smaller than the area of electrodes 3 and 4,
The solder 12 does not protrude to areas other than 4, the risk factor of creeping discharge is eliminated, the external connection part 6 and the external connection part 10 do not overlap, and the middle of one of the external connection parts 10 becomes the twisted part 9, and the tip Since the part is perpendicular to the attachment part 8, that is, in a perpendicular relationship to the external connection part 6, the fluidity of the coating resin in this part is extremely good, and an excellent exterior resin 13 with no exterior uncoated part can be obtained. At the same time, the external connection part 10 of the second electrode terminal 11 is formed.
Since the tip is perpendicular to the external connection part 6 of the first electrode terminal 7, even if the distance t between the external connection part 6 and 10 is narrow, a sufficient distance between the terminals can be obtained, and the size can be reduced accordingly. Further, since both of the electrode terminals extending to the outside are made of metal plates, there are many advantages such as there is no risk of wire breakage even if the device is subjected to 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. 6 and 7 will be described based on experimental results. i.e. diameter 13.5
Silver electrodes with a diameter of 11.4 mm were formed on both sides of a zinc oxide-based varistor body that was molded and sintered to a thickness of 2.5 mm and set at a rise voltage (V1 mA) of 470 V. The present invention (A) in which the diameter H of the electrode attachment part of the terminal is 11.0 mm and the diameter H of the attachment part of the electrode plate to the electrode shown in Figure 7 is 13.5 mm.
Figure 5 and Table 1 show the results of investigating the rate of change in the number of square wave energy applications - V1mA and the dielectric breakdown caused by creeping discharge compared to the conventional reference example (B). Note that the electrode terminals in both (A) and (B) are solder-plated with iron-nickel alloy. In addition, the number of applications in Figure 5 is when 20 msec square wave energy of 200 J 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.

[Effect of idea]

According to the present 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 cross-sectional view taken along line E--E in FIG. and a perspective view showing the first electrode terminal configuring FIG.
Fig. 4 is a perspective view showing the second electrode terminal that constitutes Figs. 6 is a plan view, and FIG. 7 is a sectional view taken along the roller 6 in FIG. 6, showing a high power varistor according to a reference example. 1... Ballista element body, 2... Outer periphery, 3, 4...
... Electrode, 5 ... Electrode mounting part, 6 ... External connection part,
7...First electrode terminal, 8...Electrode mounting part, 9...
Threaded portion, 10...External connection part, 11...Second
Electrode terminal, 12...Solder, 13...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, an electrode mounting part with a diameter smaller than the area of the electrode, and an arbitrary point on the mounting part. A first electrode terminal integrally molded with a protruding external connection part, an electrode mounting part having a diameter smaller than the electrode area, and a part of the mounting part protruding from an arbitrary part is a twisted part, and the tip part is perpendicular to the electrode mounting part. The second integrated external connection part is shaped like
A high-power varistor comprising: an electrode terminal, wherein both external connecting portions are led out in the same direction without overlapping each other, and electrode mounting portions are connected to each of the electrodes via solder, and an exterior resin is applied. .