JPS58132902A - Laminated varistor and method of producing same - 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 The present invention relates to a north laminated varistor which eliminates assembly nesting.

In recent years, zinc oxide type varistors have been developed with an excellent voltage of 4tIt.
, is used in various fields due to its non-ll1L line characteristics, for example,
The one shown in Fig. 1, which is used as a series of 1-type vessels, is made of zinc oxide as the main component and additives such as bismuth chloride, and is produced using a well-known manufacturing method, ie, pulverization.

Through the processes of mixing, granulation, molding, high creeping resistance treatment, and firing, the varistor body (73) is formed, and electrodes (83t8) are attached at both ends.
It is raised by the barista (9) with J e Q.

A plurality of varistors (9) configured in this way are stacked, for example, as shown in Figure 42, depending on the rating of the lightning arrester.
It can be assembled into one piece using insulating tubes, etc. For this reason, there was a problem in that assembly work was time-consuming.

Ninth, the above assembly work can be omitted by joining the varistor bodies (91) by soldering, or by so-called hot pressing, which involves inserting metal electrodes between the varistor bodies before sintering and sintering them together. Alternatively, methods such as stacking multiple varistor bodies and sintering them as one unit are possible.However, with manufacturing methods using soldering or hot pressing, it is difficult to expect a reduction in manufacturing costs, and the varistor The method of sintering several main bodies 41 into one body had drawbacks such as a problem of uniformity and a tendency for partial effects of leakage current to increase.

The present invention has been made in view of the above, and provides a laminated varistor in which varistor bodies and electrodes are alternately arranged, and a method for manufacturing the same.

Even if a varistor is carefully manufactured, it is extremely difficult to eliminate non-uniformity in leakage t-flow. Therefore, for example, using a varistor body with a diameter of 80 mm and a thickness of 25 mm, with metal electrodes arranged for each thickness, is of great significance because the non-uniformity of leakage current is compensated for by the gold A14 poles.

The current density is 10-'-10-'A10! +1"V The resistance value of the varistor body is equivalent to 107Ω or more, and for example, when the electrode dimensions are s Omm in diameter and 2mm in thickness, theoretically, it is 1O-80 with metal aluminum (it will be larger when sprayed), Zinc oxide rmm seismic intensity.It is desirable for electrodes to have low resistance and specific resistance, but in view of the current density used in varistors and the reality of managing leakage current distribution in the range of -1000 Ω or less in this range. Zinc oxide having a specific resistance of (therefore, the resistance value is less than 10" of the varistor body), or zinc oxide with appropriate additives, can be fully utilized as an electrode material.

Therefore, in the production of the above-mentioned varistor body, the combination of raw materials (hereinafter referred to as varistor composition) that provides the four predetermined air properties, raw materials (especially particle size distribution), crushing, mixing, granulation process, molding conditions (especially molding pressure), ), the shrinkage rate from molding to sintering varies depending on the final firing conditions, etc.
There is usually not much freedom in terms of ensuring the required quality depending on the process.

Ninth, when the electrode is manufactured under the same conditions as the varistor body, or, for example, when the electrode is formed by punching from a raw material formed into a plate shape, the varistor body is manufactured under the same conditions except by the normal molding method (electrode Processing in this way improves the homogeneity 9 work efficiency), when the can pressure 4
The flow nonlinearity is small, and one 4i dense f is lo1 ~ 10-'
In order to obtain a laminated sintered body in which electrodes are inserted between several varistor bodies and which satisfies the condition that the resistivity is 1000Ω8m or less in the A/'Qm' region, several additional techniques are required. It is necessary to add additional elements.

First, the contraction rate of the negative pole is close to the contraction rate of the varistor body. This is achieved by optimizing the conditions for the press forming of the electrode molding or the roll used to form the plate shape, and in relation to these conditions, controlling the amount of additives and organic binder in the -i formulation. be done.

Next, in the sintering process, the varistor blending part and the electrode blending part are joined by a diffusion mechanism or the like. If sufficient bonding between the varistor body and the electrodes is not achieved, there will be defects such as destruction starting from there when a large 4ft impulse is applied to that part.

If the difference in shrinkage rate between the electrode compounding part and the varistor compounding part is large, an hourglass-shaped protrusion or constriction will occur when they are sintered together, and the bond will likely be incomplete.

In order to maintain the consistency between bondability and shrinkage rate as described above, it is extremely effective to control the amount of bismuth oxide in the electrode formulation when both formulations contain at least bismuth oxide.

That is, the barista formulation was changed to bismuth oxide (BisOa
)0.5mo”1%, cobalt oxide (OosO5)
0.5m01'J, manganese oxide (MnO) 0.5m
1%, antimony (8b) 1. omall, .

Chromium oxide 0.5 engineering lq/b with silicon oxide (S10♀
)0.5no1%, aluminum nitrate (kt(NOs
)! I 30. O05mo1%, oxidized! JR salary (no 0
) In the remaining part, the molding density is 3.5 g/cm', and the 4-pole composition is layered bismuth (Bil103) 1.0 mol,
diacid) Hichikune (TiO2) 3. omo1%, aluminum nitrate (At(NO3)+)O,1mo1%,
Good results were obtained when the remaining zinc chloride (Zno) was used.

With the above composition, a varistor body (1) of the same diameter and 4 = punched from a plate-shaped material by a well-known method.
tz+ and FII alternately as shown in Figure 3, and go through the normal selling process at a sintering temperature of about 950°C or higher, sufficient bonding and sintering can be achieved with just 0 sintering. .

Here, when the thickness of the C1 varistor body fi+ is smaller than the diameter, the minimum dimension changes from the thickness to the diameter due to the product 1-, and the organic binder is removed sufficiently. The third technique that should be considered as beauty. For example, the barista itself!
An example of this is to hold the binder for 11 alone for a time longer than the time multiplied by a value larger than the diameter of 11 divided by the thickness of the varistor body 11+. (Temperature held midway, maximum held 1 degree), oxygen partial pressure, ventilation frequency, etc. are the control parameters for one car.

If this binder removal is insufficient, for example, sintering
When interrupting at CI'C and cutting the varistor body (1), it was confirmed that a clearly deteriorated part 2 remained in the center. Even if such a varistor body (11) is properly sintered, it will be of poor quality in terms of leakage current distribution, discharge resistance, etc.

Figure 3 shows an embodiment of the invention, in which the molded varistor bodies (1) and electrodes (2) are alternately arranged and stacked, and the organic binder is removed so as to satisfy the above elements. By performing the pre-sintering, a laminated varistor (3) in which the varistor body (1) and the electromagnetic material (2) were integrally bonded and sintered was obtained. This multilayer varistor (3) has almost the same shedding current distribution, short wave tail resistance, and long wave tail resistance characteristics as a comparison single varistor (91 stacked in the same number).

However, in the accelerated life test, the value was slightly lower than that of the control product, but it was a value that would not cause any practical problems.

The slight difference in the performance of the above-mentioned Hitomi is mainly due to 1 Jl of money! This is presumed to be due to the thermal conductivity of the #4 beam and the metal spacer, and the thermal conductivity of the 4-electrode material made of zinc oxide as a living body. In order to compensate for thermal conductivity, is there a way to reduce the leakage current distribution in the center at the same temperature? ? Possible methods include filling the 1-kyo tube so that the central part is convex, or molding it with an upper mold with a concave surface after flat filling, and making the four bars form a concave lens shape with the same curvature as the varistor body. It will be done.

According to this invention, there is a varistor body molded with zinc oxide as the main component and having a predetermined 4-air property, and a varistor body with a predetermined varistor body that is molded with zinc oxide as the main component and has magnetic properties that are extremely smaller than the 4-air properties of the varistor body. By applying organic binder removal treatment, conversion, and sintering, it is possible to manufacture product 1-halisk with excellent bonding properties between the varistor body and the 4-barrel. can. This allows the varistor assembly work to be omitted.

[Brief explanation of drawings]

Figure 1 is a normal rkJ diagram showing a conventional varistor. Figure 2 is a front view showing the assembly of Figure 1, and Figure 3 is a normal rkJ diagram of a laminated varistor according to an embodiment of the present invention. In the figure, (1) is the varistor body, (February i′1ll
(3) is a laminated varistor. - The same reference numerals in each figure indicate the same or equivalent parts. Agent Kuzuno 1° - Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] (11-11) Between a plurality of varistor bodies which are mainly composed of zinc oxide and have a predetermined voltage non-linearity, the voltage and current non-linearity is smaller than the voltage and current non-linearity of the varistor bodies which are mainly composed of zinc oxide. A laminated varistor characterized in that electrodes having voltage flow non-III#I characteristics are arranged between each of the varistor bodies and at both ends and are connected to each of the varistors. (2) The voltage 4fL characteristic has a predetermined nonlinearity. Fi6!1 is made from several varistor bodies made of raw materials blended as follows, and a J-ball material blended so that the voltage 4 current characteristics are smaller than the voltage 4E current non-U female of the varistor body.
1! A method for manufacturing a laminated varistor, characterized in that one 46 is arranged alternately, subjected to an organic binding removal treatment, and then sintered. (3) Claim 2, characterized in that the composition of the varistor body and the electrode and the processing conditions of the varistor are adjusted so that the yields after molding and until the completion of sintering are approximately equal. Side 1 of the description - Method for manufacturing a varistor. (3) The electrode is formed from a raw material into a plate shape of a predetermined thickness, punched into a predetermined size, and then subjected to an organic binder removal process. 2. Method for manufacturing a laminated 15 lister in the area described in item 2. (4) The organic binder removal process is performed by forging for a time obtained by multiplying the organic binder removal time in the non-laminated varistor manufacturing method by the value obtained by dividing the diameter of the varistor molded body by the thickness of the varistor molded body. A method for manufacturing a laminated varistor according to claim 2, characterized in that: