JPH0684612A - Production of small varistor - Google Patents

Abstract

PURPOSE:To produce a small varistor in which terminal wires can be fixed easily and positively with reduced quantity of solder. CONSTITUTION:When a lead 3 is soldered onto an electrode 2 formed on a varistor element 1, the lead 3 is bent circularly at the tip thereof and placed on the electrode 2. Solder 4 is then fused on the inside of the circle, i.e., a joint, or molten solder is dripped on the inside of substantially circular, semicircular, or U-shaped tip part of the lead thus soldering the lead 3 and the electrode 2. Since the solder 4 does not spread to the outside of a circle formed at the tip of the lead 3 but used effectively for jointing of the lead 3 and the electrode 2, rigid joint can be established with small quantity of solder with no possibility of adhesion of solder to unexpected parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a small varistor, and more particularly to mounting a terminal wire of a small varistor.

[0002]

2. Description of the Related Art Conventionally, as a method of attaching a terminal wire to an electrode of a small varistor, the conductor wire is left as it is (FIG. 3 (a)).
Alternatively, the tip of the conductor wire that becomes the joint is processed into a flat shape (see FIG. 3).
(b)), or a method of soldering the electrode surface of the varistor by processing the tip of the conductive wire to be a joint into a brim shape (FIG. 3C). In the figure, 21 is a varistor element body, 22 is an electrode, 23 is a conducting wire, and 24 is a solder. In this case, attach the solder to the electrode surface of the varistor in advance and press the joint part of the conductor wire on it to heat fusion, or place the joint part of the conductor wire on the electrode face of the varistor and hang the solder to cover it. Are fused and joined together.

[0003]

One of the problems encountered here is that molten solder flows more than necessary and spreads and adheres to the side surface of the varistor to cause creeping flashover of the surface of the varistor. There is a risk of directly touching the body and deteriorating the electrical characteristics of the varistor. Further, in the conventional method, the conductor wire is often deviated from the central portion of the attached solder, and in such a case, the solder is not effectively used for the purpose of joining and sufficient joining strength cannot be obtained. For this reason, in the conventional method, much more solder than is originally required for bonding is used, which is not only uneconomical, but also adds extra heat to the varistor element body, which is also in terms of device characteristics. Not preferable.

The present invention has been made in order to eliminate such drawbacks of the prior art, and an object thereof is to provide a method for manufacturing a small varistor which requires a small amount of solder and enables easy and reliable attachment of terminal wires. To do.

[0005]

In order to achieve the above object, according to the present invention, a metal oxide powder is formed into a disk shape or a column shape, and the obtained formed body is sintered at a high temperature. After producing the varistor element body, an electrode is formed on the varistor element body, and then the tip of a conductor wire whose tip is processed into a substantially circular shape, a semicircular shape or a substantially U shape is applied to the electrode surface, The solder is melted inside the substantially circular shape, the semi-circular shape, or the substantially U-shape, or the molten solder is hung down inside the substantially circular shape, the semi-circular shape, or the substantially U-shape of the leading end of the conductive wire to solder the conductive wire and the electrode. A method of manufacturing a compact varistor is provided.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a constitutional view of a small varistor manufactured by the method of the present invention, in which 1 is a varistor element body, 2 is an electrode, and 3 is an electrode.
Indicates a lead wire and 4 indicates solder. In the method of the present invention,
First, a powder of a metal oxide containing zinc oxide, titanium oxide, barium titanate or the like as a main component is formed into a disc shape or a column shape. In this case, Bi ₂ O ₃ , MnO, CoO, Sb
₂ O ₃ , Cr ₂ O ₃ , PbO, SrO, BaO, Al ₂
O ₃ , SnO ₂ , SiO ₂ , TiO ₂ , NiO, Mg
A small amount of O, CaO, Pr ₆ O ₁₁ or the like may be added.

Next, the disk-shaped or column-shaped molded body obtained above is sintered at 800 to 1500 ° C. to form a varistor element body 1, and then electrodes 2 are formed on both surfaces of the varistor element body 1. As the electrode forming method, known means such as plating treatment, paste baking treatment, vapor deposition and the like can be used.

Next, the electrode 2 formed on the varistor element body 1
Solder the conducting wire 3 on the surface. At that time, as shown in FIG. 1, the tip of the conductive wire 3 is bent in a circular shape, the tip is placed on the electrode 2, and the circle is used as a joint to melt the solder 4 inside the circle. Alternatively, the conductor 3 and the electrode 2 are fused by hanging a molten solder inside the substantially circular, substantially semicircular or substantially U-shaped inside of the leading end of the conductor. In this way, the solder 4 does not spread outside the circle formed at the tip of the conductive wire 3 and is effectively used for bonding the conductive wire 3 and the electrode 2. As a result, firm bonding can be ensured with a small amount of solder. It is safe because there is no risk of solder sticking to unexpected parts. Further, since the amount of solder used is small, unnecessary heat is not applied to the varistor element body 1. The circle formed at the tip of the conductive wire 3 is of course smaller than the surface of the electrode 2, but its size is not particularly limited. But,
If the size of the circle is too small, the solder may cover the circle portion and form a cavity inside, which is not preferable. If it is too large, a large amount of solder will be used, which is contrary to the intended purpose of the present invention. Therefore, the inner diameter of the circle formed at the tip of the conductive wire 3 is preferably about 1.5 to 5 times the thickness of the conductive wire 3. Further, in the example of FIG. 1, the shape of the joint formed at the tip of the conductive wire 3 is substantially circular, but a similar effect can be obtained even if it is substantially semicircular or U-shaped. The joint may be a round wire or may be flattened.

Next, an example of manufacturing a small varistor according to the present invention will be described with reference to FIG. A powder product containing zinc oxide as a main component and 5 mol% of manganese oxide added thereto was molded into a disk shape, and this molded body was sintered at 1200 ° C. for 60 minutes to obtain a varistor element body 11. Next, silver glass paste was baked on both surfaces of the varistor element body 11 to form the electrodes 12. On the other hand, one conducting wire 13 was bent from the central portion into two, and the leading end portion of the conducting wire 13 was formed into a closed circle. The inner diameter of this circle was about 2.5 times the thickness of the conducting wire 13. The circular portion at the tip of the conductive wire 3 was applied to the surface of the electrode 12 as a joint portion, and the solder 14 was placed inside the circle and heated and fused. After that, the conductor 13 is bent near the bent portion (see FIG. 2).
(A-B part) to be an electrode terminal wire. In the varistor thus manufactured, the electrode terminal wires are extremely strong against pulling and peeling, and the amount of solder used is about one fifth of that of the conventional method, and the bonding is extremely short. Completed. The solder barely covered the conductive wire and did not spread outside the joint.

In the above-mentioned production example, one conductor wire is folded in two and used, but the conductor wire may be folded in four so that the tips of one conductor wire face each other, or two conductor wires may be used from the beginning. It is needless to say that the conductor wire may be used.

[0011]

As described above in detail, according to the present invention, the tip of a conductor wire whose tip is processed into a substantially circular shape, a semicircular shape or a U shape is applied to the electrode surface formed on the varistor element body. , Melting the solder inside the substantially circular, substantially semi-circular or substantially U-shaped end of the conducting wire, or hanging the molten solder inside the substantially circular, substantially semi-circular or substantially U-shaped leading end of the conducting wire Since the electrodes are soldered, the amount of solder used can be extremely reduced and a strong joint can be obtained. Further, it is suitable for automation because the electrode terminal wire can be attached easily and surely.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method for manufacturing a small varistor according to the present invention.

FIG. 2 is an explanatory diagram of an example of manufacturing a small varistor according to the present invention.

FIG. 3 is an explanatory view of a method of attaching electrode terminal wires in a conventional small varistor.

[Explanation of symbols]

 1 Varistor element body 2 Electrode 3 Conductor wire 4 Solder

Claims (2)

[Claims] 1. A metal oxide powder is formed into a disc shape or a column shape, the obtained formed body is sintered at a high temperature to prepare a varistor element body, and then an electrode is formed on the varistor element body, The tip of a conductor wire whose tip is processed into a substantially circular shape, a substantially semicircular shape, or a substantially U shape is applied to the electrode surface, and solder is melted inside the substantially circular shape, the substantially semicircular shape, or the substantially U shape of the leading end portion of the conductive wire, or A substantially circular shape, a substantially semicircular shape, or a substantially U shape of the leading end portion of the conducting wire
A method for manufacturing a small varistor, which comprises smelting molten solder inside a letter shape and soldering the conductor wire and the electrode. 2. The soldering is performed by setting the inner diameter of the substantially circular shape, the substantially semicircular shape, or the substantially U-shaped portion of the leading end of the conductive wire to 1.5 to 5 times the thickness of the conductive wire. Item 2. A method for manufacturing a small varistor according to Item 1.