JPH08162000A - Fuse and its manufcture - Google Patents

Abstract

PURPOSE: To provide a fuse which can solve the problem of an arc discharge occurring as a result of the fusion of its fuse wire by enabling suspending the fuse wire while maintaining a certain tensile force, providing a partition wall in a cavity, and providing outside the partition wall a portion where the fuse wire is secured to each metallic cap; is easy to assemble; and has high productivity and to provide a method for manufacturing the same. CONSTITUTION: A chip type fuse comprises a ceramic case main body 2 and a cover 3 which are fitted together to provide a cavity inside and an outer contour in the form of a rectangular solid; a fuse wire 1 held in the main body 2 or in the dent 5 of the cover 3 at both ends of a case and suspended across the cavity inside the case, and metallic caps 7 fitted over both ends of the case and electrically connected to the fuse wire 1. A case structure is provided in which a partition wall is provided between the cavity and the junction between the fuse wire and each metallic cap.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuse, and more particularly to a microminiature fuse which can be surface-mounted on a printed wiring board or the like and a method for manufacturing the fuse.

[0002]

2. Description of the Related Art Conventionally, various types of fuses have been proposed as this type of fuse. For example, the actual development Sho 59-11
According to Japanese Patent Publication No. 9546, a resin-sealed fuse is proposed, which has a structure in which a chip-shaped body has a hollow space and a fuse wire is stretched in the hollow space. According to Japanese Utility Model Laid-Open No. 5-72033, a fuse having a structure in which a hollow space is provided in the main body of a prism and a fuse wire is obliquely stretched in the hollow space and both ends thereof are sealed with a cap is proposed. Has been done. Furthermore, real public Sho 59-
According to Japanese Patent No. 21500, a box-shaped ceramic case is provided with convex fuse wire locking portions at both ends, the inside is made into a hollow space, and a fuse wire is stretched between the locking portions at both ends to cover the ceramic lid. There is disclosed a microminiature fuse which is covered with a rectangular parallelepiped fuse.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In a fuse,
If the length of the fuse wire cannot be made constant due to loosening of the fuse wire and loosening, there is a problem that the fusing performance becomes extremely different. Further, in a short circuit breaking performance test or the like, when the fuse wire is blown by a current of 100 volts or more and about 100 amps, an arc current is generated. Even after the fuse wire is blown, energization is caused by the arc current and the energization time becomes long, so that the amount of heat generated in the case becomes high, and as a result, the case is destroyed due to an increase in internal pressure. This is because when the fuse wire melts down, the sublimation material such as solder that fixes both ends of the fuse wire inside the case is gasified in the hollow space, and this gas serves as a nucleus to continue the arc current. it is conceivable that.

Therefore, Japanese Utility Model Publication No. 59-21500 discloses a technique in which a wall of a crank-shaped convex portion is provided in a hollow space in which a fuse wire is stretched, and both ends of the fuse wire are fixed to the case outside the wall. Proposed. However, in the structure proposed in Japanese Utility Model Publication No. 59-21500, crank-shaped protrusions are provided at the ends of the hollow space and the fuse wire is stretched at both ends thereof. Therefore, there is a problem that the structure becomes complicated and that the assembly of the stretched fuse wire is not easy.

The present invention has been made in view of the above circumstances, and the fuse wire can be stretched while maintaining a constant tension.
By providing a partition in the hollow part and providing a fixing part to the metal cap of the fuse wire on the outside thereof, the problem of arc discharge at the time of fusing of the fuse wire is prevented, and the fuse is easy to assemble and has high productivity. It is intended to provide a manufacturing method.

[0006]

SUMMARY OF THE INVENTION A chip-type fuse of the present invention comprises a ceramic case body and a lid body which are fitted together to form a hollow interior and a rectangular parallelepiped exterior, and recesses of the body or the lid body at both ends of the case. A fuse cap that is held by a portion and is stretched in a hollow portion inside the case; and a metal cap that covers both ends of the case and is electrically connected to the fuse wire. It is characterized by having a case structure in which a partition wall is provided between.

According to the method of manufacturing a chip-type fuse of the present invention, a ceramic case body and a lid body, which are fitted together to form a hollow interior and a rectangular parallelepiped exterior, are prepared, and either one of the ceramic case body and the lid body is prepared. The fuse wire is dropped in a recessed portion provided in the device in a state where tension is applied and fixed to the recessed portion with an adhesive, and then the fuse wire is cut, and the ceramic case body and the lid are adhered and fixed to each other. And a lid to form a partition wall, and the fuse wire is stretched over a portion having a hollow interior, and the main body and the lid are fitted to each other at both ends of the ceramic case. It is characterized in that a metal cap is fitted and solder is loaded into the metal cap to connect both ends of the fuse wire outside the partition wall.

[0008]

[Function] Since the external parts are fitted into each other to form a rectangular parallelepiped shape and both ends of the fuse wire are stretched in the internal hollow space,
The fuse wire is stretched in the hollow space by a constant tension. This solves the problem of variation in fusing characteristics. Since both ends of the fuse wire are held by the recessed portion of the main body or the lid and fixed to the metal cap by solder on the outside blocked by the case partition wall, diffusion of the adhesive agent to the hollow portion occurs at the time of fusing. The problem of continuous arc discharge is prevented. Further, by fitting the ceramic case body and the lid body in a state where tension is applied to the fuse wire, covering the metal case with the fuse, and fusing with the solder, the fuse having the above structure can be manufactured very easily. Therefore, according to the present invention, it is possible to mass-produce a fuse having good fusing characteristics and having no problem of arc discharge at a low manufacturing cost.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

FIG. 1 is an exploded view of a chip type fuse according to an embodiment of the present invention. The fuse wire 1 is stretched in a hollow space of a rectangular parallelepiped case formed by fitting a ceramic case body 2 and a lid 3 together. The fuse wire 1 is dropped into the hollow portion 5 of the case body 2 and sandwiched by the lower end surfaces 6 of both ends of the lid body 3. The ceramic case body 2 and the lid body 3 are fitted to each other to form a rectangular parallelepiped shape, and metal caps 7, 7 are covered on both ends thereof.

Both ends of the fuse wire 1 are temporarily fixed to the recessed portion 5 of the case body 2 with an adhesive, and both ends thereof are bent along the side end surface 2A of the case body 2. An adhesive such as epoxy is applied to the side end surface 3B of the lid 3 of the ceramic case, the lid 3 is fitted to the case body 2, and both end surfaces 3B and 3B of the lid 3 are the inner end surface 2 of the case body 2.
It is designed to be bonded to C and 2C. The metal cap 7 is, for example, a Cu material or a Cu alloy material plated with solder, and a preliminary solder 9 is attached to an inner end surface 7C of the case body 2 facing the end surface 2A. Therefore, when the lid 3 is fitted to the case main body 2 and the metal caps 7 are fitted to both side ends of the rectangular parallelepiped case and heated, the preliminary solder 9 melts with the bent portion 1D of the fuse wire of FIG. To wear. As a result, the metal cap 7 is fixed to the ceramic case and the bent portions 1D, 1D of the fuse wire 1. Further, the adhesive 10 applied to the upper surfaces of both ends of the lid 3 adheres and is fixed to the inner upper surface 7B of the metal cap 7.

As described above, the case of the chip-type fuse has a two-part structure of the main body 2 and the lid body 3. After the two divided cases are bonded with an adhesive, a metal cap is press-fitted. . As shown in the drawing, when a notch is formed in a portion 2E of the case main body 2 and the notch 3E is fitted to a portion of the lid 3 and serves as a stopper, the lid 3 can be easily positioned. If dimensional variation occurs due to the case bonding of the main body 2 and the lid body 3 before the metal cap is fitted, the cap cannot be properly press-fitted and fitted. Therefore, the lid body 3 is dropped into the groove portion of the main body 2 so that the fitting portion of the metal cap is stable, thereby improving the dimensional accuracy. Therefore, the dimension A of the lid 3 is set smaller than the dimension B of the case body 2, and the dimension C of the lid 3 is set smaller than the dimension D of the case body. Similarly, the length E of the lid body 3 in the longitudinal direction is smaller than the length F of the case body 2 in the longitudinal direction, so that the lid body 3 does not protrude from the case body 2. The vertical and horizontal dimensions of the end surface 2A of the case body 2 are set to the inner end surface dimensions of the metal cap 7 to obtain the required accuracy.

FIG. 2 is a side view (A) and a top view (B) of a fuse according to a second embodiment of the present invention. In this embodiment, the land pattern of the printed circuit board and the lower surface electrode to be soldered when mounted on the printed circuit board protrude from the case by the thickness of the cap, but the other three surfaces are flat with the cap and the ceramic case surface. There is. In this embodiment, by making the upper end surface of the chip case flat, including the metal cap portion, the vacuum chuck when mounting the printed circuit board is facilitated. Further, when the display mark is printed on the upper end surface, the work can be facilitated and the marking space can be widened.

FIG. 3 shows a method of manufacturing the above-mentioned fuse. First, as shown in FIG.
Mark B. Then, the fuse wire is pulled out from the feeder with a certain tension, and is dropped into the recess 5 of the case body 2. And the hollow portion 5
Then, it is temporarily fixed with an adhesive, is cut off slightly from the end surface 2A of the main body, and the fuse wire is bent along the end surface 2A. Then, as shown in (B), an adhesive such as epoxy is applied to the side end surface 3B of the lid body 3 and the lid body 3 is fitted to the main body 2. Then, while pressurizing the lid 3 against the main body 2, for example, 1
By heating for about 5 minutes, the adhesive hardens and the lid 3
And the main body 2 are fixed. Next, the inner end surface 7 of the metal cap 7
Solder pieces or cream solder are supplied to C and heated to form the preliminary solder portion 9. Then, the adhesive 10 such as epoxy is applied to the fitting portion of the metal cap on the lid 3 of the rectangular parallelepiped chip case. Then, as shown in (C), the caps 7 on which the preliminary solder portions 9 are formed are press-fitted to both ends of the rectangular parallelepiped chip case, and, for example, 300
The adhesive is hardened by heating at 3 ° C. for about 3 seconds to fix the cap 7 to the chip case, and solder is welded to strengthen the electrical connection between the fuse wire 1D and the metal cap 7. Thus, the manufacturing process of the fuse of the above-described embodiment is completed, and the fuse of this embodiment is completed through measurement and inspection of electric characteristics.

In order to make the upper end surface flat as in the second embodiment shown in FIG. 2, the metal cap fitting portions at both ends of the chip case are thinned in advance by the thickness of the metal cap. Need to be kept. By subjecting both ends of the main body 2 to the above-described processing in advance, the fuse of the second embodiment shown in FIG. 2 can be manufactured by the same manufacturing process as described above.

What is important as the quality of the fuse is the stability of the fusing characteristics. In prior art tube fuses, for example, a fuse wire is threaded through the tube and a cut is thrown into the edge of the tube to press fit the cap. Therefore, since the fuse wire is only hooked to the edge of the tube and no tension is applied, the fuse wire is loosened and the fuse wire length varies, and this variation causes variation in the fusing characteristics. As described above, in the fuse of this embodiment, the fuse wire is stretched over the recessed portions 5 at both ends of the case while the tension is applied, and is fixed with an adhesive, so that the fuse wire length is constant and the fusing characteristic is stabilized. You can

Further, as described above, in the microminiature fuse, if the fuse wire and the portion fixed to the terminal electrode are in the same hollow space, arc discharge is likely to occur when the short circuit is interrupted. In the fuse of this embodiment described above, the fuse wire 1 is sandwiched between the fuse body 1 and the lid 3 through the recess 5 of the body 2. Then, it is welded to the metal cap 7 by soldering on the outer end surface of the case, which is a wall surface composed of the main body 2 and the lid 3. Therefore, the soldered portion of the solder is isolated from the inside of the hollow space where the fuse wire 1 is fused by the side end surfaces of the main body 2 and the lid 3 acting as partition walls. Therefore, when the fuse wire is blown, the problem that the fixed portion of the fuse wire, that is, the portion fused by solder is gasified and the arc discharge is continued can be prevented, and a stable breaking characteristic can be obtained in a short-circuit breaking test or the like.

That is, the third table of the Electrical Appliance and Material Control Law of this embodiment
10 in the short-circuit breaking performance test specified in Appendix Table 2
When a voltage of 0 V or more and 100 A (ampere) is applied, an arc current is generated in the structural product without a partition wall, and the arc current continues to be energized even after the fuse is blown. It was high, and as a result, there were often cases where case damage occurred due to an increase in internal pressure. In the same test in which the partition wall of this example was provided, no arc current was generated after fusing and the internal calorific value was low, so the case was not damaged. As described above, by providing the partition wall, the problem of continuation of the arc current at the time of interruption does not occur, and a high-current fuse becomes possible.

Further, in the fuse of this embodiment, the case has a two-part structure, and the fuse wire is stretched linearly in the approximate center of the hollow space in the case. Therefore, the structure is simple and its manufacture is easy. is there. Therefore, the fuse wire can be easily attached, and the processing such as improving the time lag characteristic by attaching a solder wire or the like to the changed wire or the central portion of the fuse element after installation can be easily performed.

Further, in the present embodiment, the hollow portion 5 into which the fuse wire is dropped is provided on the case body 2 side, but it goes without saying that it may be provided on the lid body 3 side. Further, conductors may be printed and baked on both end surfaces 2A, 2A of the case body. As a result, the fuse wire bent portions 1D, 1
Connection with D becomes easier.

[0021]

As described above, in the fuse of the present invention, the fuse wire is stretched around the center of the hollow portion of the case having the two-division structure, and the partition wall is provided between the hollow space portion and the fixed portion of the fuse wire. It is provided. Therefore, there are few variations in the temperature rise characteristics, the energization characteristics, and the fusing characteristics, and good short-circuit breaking characteristics can be easily achieved with the prevention of arc discharge. Since the case has a two-part structure, the structure is simple and the manufacturing is easy. Therefore, the defect rate in mass production is very small, stable production is possible, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is an exploded view of a fuse according to a first embodiment of the present invention.

FIG. 2A is a side view and FIG. 2B is a top view of a fuse according to a second embodiment of the present invention.

FIG. 3 is an explanatory view showing a manufacturing process of a chip resistor according to an embodiment of the present invention.

[Explanation of symbols]

 1 Fuse wire 2 Case body 3 Lid body 5 Recessed portion 7 Metal cap

Claims (2)

[Claims] 1. A ceramic case body and a lid body which are fitted to each other and have a hollow inside and a rectangular parallelepiped outside, and both ends of the case are held by a hollow portion of the body or the lid body and stretched in a hollow portion inside the case. A case structure having a bridged fuse wire and a metal cap that covers both ends of the case and is electrically connected to the fuse wire, and a partition is provided between the hollow portion and the metal cap joint portion of the fuse wire. Fuse. 2. A ceramic case body and a lid body, which are fitted together to form a hollow interior and a rectangular parallelepiped exterior, are prepared, and a fuse wire is tensioned to a recess provided in either the ceramic case body or the lid body. The fuse wire is cut in a state of being dropped and fixed to the recessed portion with an adhesive, the ceramic case main body and the lid are adhered and fixed, and the main body and the lid are fitted together to form a partition wall. The fuse wire is stretched over the formed hollow portion, and metal caps are inserted into both ends of the ceramic case formed by fitting the main body and the lid body, and the metal cap is loaded into the metal cap. A method of manufacturing a fuse, characterized in that the fuse is connected to both ends of the fuse wire outside the partition wall.