JPS6235601A - Manufacture of multipolar varistor - 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] [Technical field of invention] The present invention relates to a method for manufacturing a multipolar varistor.

[Technical background of the invention and its problems] Varistors are generally connected to the input portions of circuits to protect various circuits from surges absorbed by induced lightning or switching of inductive loads. Varistors have excellent surge resistance, absorbing most surges, and play an extremely effective role in protecting various circuits, and their range of applications is likely to expand further in the future. However, in recent years, there has been remarkable progress in the development of microelectronic devices such as calculators, electronic clocks, cameras, radio receivers, etc., and these microelectronic devices are composed of numerous electronic circuit components. However, static electricity is always directly input to the circuits that make up these microelectronic devices, and in order to protect individual circuit components from the static electricity, it is necessary to install varistors formed into microminiatures for each component. However, there was also the problem of increasing the size of the electronic equipment itself.

Therefore, as shown in FIGS. 5 and 6, a common electrode (1
2) is divided into many electrodes (13) on the other side.
The above problem can be solved by using a multipolar varistor formed with .

Conventionally, the common electrode (12) and the electrode (1
Formation method a) was carried out by screen printing an electrode material paste along the initially set electrode pattern. However, as shown in FIG. 7, there is a flow of screen-printed electrode material paste (14), so taking this into consideration, the electrode (14) formed on the other side of the varistor body (11) is
13) In addition, when two or more electrodes (13) are formed on the same surface, the varistor voltage on the surface layer of the varistor body (11) is lower than that inside the body. In order to prevent mutual creepage discharge between the electrodes (13), the distance H between the electrodes (13) must be maintained at a value greater than the thickness t1 of the varistor body (11), which results in the size of the device becoming larger and becoming a microelectronic device. It could not be a suitable multipolar varistor.

[Object of the Invention] The present invention has been made in view of the above points, and an object of the present invention is to provide a method for manufacturing a multipolar varistor that does not cause creeping discharge between electrodes and can be miniaturized. .

[Summary of the Invention] The method for manufacturing a multipolar varistor of the present invention includes a method for forming and sintering ceramic powder to obtain a square plate-shaped varistor body, and a method for producing a varistor body by leaving outer peripheral edges on both sides of the varistor body after the means. It is characterized by comprising a means for forming a rectangular electrode, and a means for forming a plurality of grooves extending to the varistor element on one electrode surface and dividing the electrode on one side into a plurality of independent parts. be.

[Embodiment of the Invention] An embodiment of the present invention will be described below. First, as shown in FIGS. 3 and 4, ceramic powder is molded and sintered to form a rectangular plate-shaped varistor body (1) of a desired size, and then the varistor cord body (1) is formed. An electrode material paste made of, for example, silver paste is applied and baked by screen printing, leaving outer peripheral edges on both sides, to form electrodes (2H3). Next, as shown in FIGS. 1 and 2, a diamond cutter or a wire saw is used on one of the electrodes (2) and (3), for example, on the surface of the electrode (2) to cut it to the varistor body (1). forming a plurality of elongated kerfs (4);
The electrode (2) is divided into a plurality of independent parts, and a plurality of "
After forming an electrode (5) and using the other side as a common electrode (6), a lead terminal (7) is attached to each of the common electrode (6) and the plurality of electrodes (5) by soldering, and then a resin mold is formed. to form an exterior resin (not shown).

According to the method for manufacturing a multipolar varistor configured as described above, the electrodes (2) before division are applied in advance as means for forming the plurality of electrodes (5) formed on one side of the varistor body (1). Since the method is to divide the electrodes by baking and then forming the cut grooves (4), the plurality of electrodes (5) can be reliably separated, the required shortest distance between the plurality of electrodes (5) can be ensured, and the cutting Since the groove (4) has a depth extending to the varistor body (1), the surface layer of the varistor body (1) where the varistor voltage is low in this part is eliminated, and the distance between the multiple electrodes (5) is reduced. In other words, the kerf (4) interval W
Even if the thickness of the varistor body (1) is reduced to less than t, creeping discharge can be eliminated, which makes it possible to downsize the entire device, and protects each ladder electronic circuit component from static electricity in microelectronic devices that have made remarkable progress in recent years. It will be most suitable for the purpose.

Next, the actual state of miniaturization will be described based on the inventor's experimental results. In other words, it is a 220V class rectangular plate-shaped varistor whose main component is zinc oxide and has a thickness of 2.1m.
In order to eliminate creeping discharge between the multiple electrodes in the conventional structure (B) shown in FIGS. 6 and 7, in which multiple electrodes are formed at the corners and a common electrode is formed on the other side, the distance between the multiple electrodes is determined. Whereas H was required to be 2.5 # or more, in order to eliminate creeping discharge between multiple electrodes in the structure of the present invention (^) shown in Figs. depth 0.5m
In this case, the distance iw between multiple electrodes is set to 1. C) It was found that it is sufficient to maintain sl, and therefore the volume ratio can be reduced by about 40%. The outer circumferential dimension of the varistor element in this experiment was (
A) (Both Bl and Bl were set to 1.5 mrR. In the above embodiment, the structure of the kerfs was explained by exemplifying one in which they intersect at right angles, but as shown in FIG. 5, simple parallel kerfs ( Of course, the same effect can be obtained in the case of 8).The same parts in FIG. 5 as in FIG. 1 are given the same numbers and their explanations are omitted.

[Effects of the Invention] According to the present invention, as a means for forming multiple electrodes on one side of the varistor body, a single electrode formed in advance is formed using a cut groove extending to the varistor body, so that the multiple electrodes can be reliably separated. It is possible to obtain a WA manufacturing method for a multipolar varistor, which has a high practical value, can minimize the distance between multiple electrodes, eliminate creeping discharge, and greatly contribute to miniaturization.

[Brief explanation of the drawing]

1 to 4 are explanatory diagrams of a method for manufacturing a multipolar varistor according to an embodiment of the present invention, in which FIG. 1 is a plan view showing the multipolar varistor, FIG. 2 is a sectional view of the multipolar varistor shown in FIG. Figure 3 is a plan view of electrodes formed on the varistor body in the process of being manufactured;
The figures are Fig. 3, a cross-sectional view of Rollo, Fig. 5, a plan view showing a multipolar varistor according to another embodiment of the present invention, and Figs. 6 to 8 show multipolar varistors according to conventional examples. 6 is a plan view, FIG. 7 is a cross-sectional view of the harbor in FIG. 6, and FIG. M8 is an enlarged view of the section X in FIG. 5. (1)... Varistor element body, (2) (3)... Electrode, (4) (8)... Cut groove, (5)... Multiple electrodes,
(6)...Common polarity Applicant Marukon Electronics Co., Ltd. 7? Lifestyle Paris 9Φ乎面次
Ya 11 Kuiyakuwa concave figure 1 figure 2 figure 7 early rtr times of squirrel 7 in kukuwarishin nz figure 5 figure 7 circle figure 8 figure

Claims (1)

[Claims] A means for forming and sintering ceramic powder to obtain a square plate-shaped varistor body; a means for forming a square electrode by leaving an outer periphery on both sides of the varistor body; 1. A method for manufacturing a multipolar varistor, comprising means for forming a plurality of grooves extending to a varistor body and providing a plurality of divided and independent electrodes.