JPH074763Y2 - Chip fuse - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip fuse, and more particularly to a structure capable of reliably performing electrical connection between a fusible body and a conductive terminal portion by pre-soldering during fuse assembly. .

[0002]

2. Description of the Related Art As a conventional chip fuse, one having a structure as shown in FIG. 6 is known (see, for example, Japanese Utility Model Laid-Open No. 64-56135).

[0003]

In FIG. 6, 10 is a main body of a prism, 12 is a conductive terminal, and 14 is a fusible body. The main body 10 is provided with a through hole 18 penetrating between both end surfaces 16 thereof and a fusible body through groove 20 on a side surface of the both end surfaces 16. The conductive terminals 12 are provided on both end surfaces 16 of the main body 10.
Has a concave portion 22 fitted to the side surface thereof, and preliminary solder 24 is applied to the inner surface of the concave portion 22. This chip fuse is assembled as follows. The fusible body 14 is the main body 10.
Through the through hole 18, and both ends of the fusible body 14 are locked in the fusible body through groove 20. Next, one of the conductive terminals 12 is heated and, while being heated, the concave portion 2 of the conductive terminal 12 is
2 is fitted from one end surface 16 of the main body 10 along the side surface thereof, and the inner surface of the concave portion 22 of the conductive terminal 12 and the fusible body 14 are fitted together.
One end is soldered. Further, the other conductive terminal 12 is similarly fitted from the other end surface 16,
The inner surface of the recess 22 of the conductive terminal 12 and the other end of the fusible body 14 are soldered to complete the chip fuse.

Since the conductive terminal 12 is heated when the other conductive terminal 12 is fitted to the other end surface 16 of the main body 10, the air in the through hole 18 of the main body 10 is also heated. The expanded air pushes the melted preliminary solder 24 from between the side surface of the recess 22 of the fitted conductive terminal 12 and the side surface of the main body 10. Therefore, there are cases where the conductive terminal 12 and the fusible body 14 are not soldered reliably, and there is a problem such as a decrease in yield or a decrease in reliability.

The present invention has been made in view of the above problems, and an object thereof is to provide a conductive terminal fitted in a main body having a through hole and a fusible body stretched in the through hole. It is an object of the present invention to provide a chip fuse having a structure that can be surely electrically connected by pre-soldering during assembly.

[0006]

To achieve the above object, a chip fuse according to the present invention is a main body made of a heat-resistant insulating material and having a shape of a columnar body, which penetrates between both end faces in the longitudinal direction. A body having a through hole and an opening communicating with the through hole on the outer peripheral surface of at least one end surface of the both end surfaces, and a fusible body stretched over the through hole, each end of which is The fusible body extends and is locked along the both end surfaces and the outer peripheral surface in contact with the both end surfaces, and a recessed portion fitted to the outer peripheral surface of the both end surfaces, and the recessed portion when fitted. And the end portion of the fusible body are electrically connected to each other via preliminary solder, and the recess includes a pair of conductive terminal portions covering the opening of the main body.

[0007]

The chip fuse constructed as described above is assembled in the same process as the assembly of the conventional chip fuse described above. However, in the step of fitting the pair of conductive terminals to the main body, the fitting on the side having the opening is performed last.
In the process of fitting the concave portion of the conductive terminal, which is heated to such an extent that the preliminary solder is melted, from the end surface on the side having the opening portion of the main body along the side surface thereof, the air in the through hole of the main body is also heated and expands. The expanded air is allowed to escape to the outside through the opening. Therefore, the expanded air does not push the melted preliminary solder from the mating surface between the recess of the conductive terminal and the side surface of the main body, so that the conductive terminal and the end of the fusible body are securely connected by the preliminary solder. It

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. Note that the components designated by the same reference numerals as those in FIG. 6 have the functions corresponding to the components of the conventional chip fuse shown in FIG.

FIG. 1 is a perspective view of a finished chip fuse of the present invention. In FIG. 1, 10 is a main body and 12 is a pair of conductive terminals.

FIG. 2 is a perspective view of the body 10 shown in FIG. The main body 10 is made of a heat-resistant insulating material such as ceramic, has a prismatic shape, and has a cylindrical through hole 18 penetrating between both end surfaces 16 along the longitudinal direction thereof. In the main body 10, a fusible body through groove 20 is formed at a diagonal position on opposite side surfaces in the vicinity of both end surfaces 16 of the main body 10, and both sides from the side surface facing the side surface where the fusible body through groove 20 is provided to the through hole 18 are formed. A slit-shaped air vent notch 26 is formed along the surface 16.

FIG. 3 is a structural view of the chip fuse shown in FIG. 1 before assembly. In FIG. 3, reference numeral 14 denotes a fusible body having an elongated shape. FIG. 4 is a cross-sectional view of the chip fuse after the components of the chip fuse shown in FIG. 3 have been assembled, as seen from the surface including the fusible body 14, the fusible body passing groove 20, and the air vent notch 26. The fusible body 14 is stretched by passing through the through hole 18 of the main body 10 at the time of assembly.
Both ends of 4 are locked in the respective fusible body through grooves 20 of the main body 10. The conductive terminal 12 is composed of, for example, a base terminal, has a rectangular parallelepiped outer shape, and has a recess 22 on one surface thereof, which is fitted from the end surface 16 of the main body 10 along the side surface thereof by press fitting. When the conductive terminal 12 is press-fitted, the fusible body passage groove 20 damages the end of the fusible body 14 by the inner wall of the recess 22 and the side surface of the main body 10, or extends the fusible body 14 in the press-fitting direction. It acts to prevent that. Preliminary solder 24 is applied to the inner surface of the recess 22. The conductive terminal 12 has a function of electrically connecting to an external circuit on the printed circuit board, and four outer surfaces of the conductive terminal 12 which are orthogonal to the recess 22 form a surface to be mounted on the printed circuit board. . One of the conductive terminals 12 is used as the spare solder 2
4 is heated to such a degree that it melts, the concave portion 22 is press-fitted from one end face 16 of the main body 10 on which the fusible body 14 is stretched along the side surface thereof, and the concave portion 22 of the conductive terminal 12 and the fusible body 14 are The ends of are soldered by the preliminary solder 24 and electrically connected. At this time, the air in the through hole 18 of the main body 10 is also heated and expanded by the heated conductive terminal 12, but since the other end face 16 side of the through hole 18 is open, the expanded air escapes from there. Next, the other conductive terminal 12 is press-fitted from the other end surface 16 of the main body 10 in the same manner as the previous conductive terminal 12 while being heated. At this time, the air in the through hole 18 of the main body 10 is heated and expanded by the other heated conductive terminal 12. The expanded air is released to the outside through the air vent notch 26. Therefore, the preliminary solder 24 melted in the recess 22 of the conductive terminal 12 is pushed out by the expanded air from between the inner wall of the recess 22 of the conductive terminal 12 and the side surface of the fitted body 10. Since it is not discharged, the melted preliminary solder 24 remains in the recess 22 of the conductive terminal 12 in a melted state. Therefore, the conductive terminal 1
2 and the ends of the fusible body 14 are reliably soldered by the preliminary solder 24 as shown in FIG. As shown in FIG. 4, the depth of the air vent notch 26 is such that the air vent notch 26 is recessed in the conductive terminal 12 so that the through hole 18 is sealed when the press fitting of the conductive terminal 12 is completed. Two
It is designed to be covered by the inner wall of 2.

In the above embodiment, in order to facilitate the assembling work by making the order of press-fitting the pair of conductive terminals 12 into the main body 10, the pair of air vent notches 26 are arranged.
One is provided on each side 16 of the main body 10,
The air vent notch 26 is provided only on one end face 16 side, the conductive terminal 12 is first press-fitted into the end face 16 on which the air vent notch is not provided, and then the end face on which the air vent notch is provided. The conductive terminal 12 may be press-fitted into the terminal 16. Further, a plurality of air vent notches are provided on one end face 1
It may be provided on the end faces 16 of 6 or both.

Since the chip fuse for mounting on the printed circuit board shown in FIG. 1 has a small size, the ceramic body 10 is manufactured by the steps of powder molding, compression and sintering. In this manufacturing process, the air vent notch 26 has a structure in which the end surface 16 of the main body 10 is notched in order to facilitate manufacturing. However, the point is that when the conductive terminal 12 to be press-fitted later is press-fitted from the end surface 16 of the main body 10 while being heated, it is a ventilation path for allowing the thermally expanded air in the through hole 18 to escape to the outside. It suffices to have a structure in which the outlet of the ventilation passage is covered by the side wall of the recess 22 of the conductive terminal 12 when the press-fitting is completed. Therefore, instead of the air vent notch 26 as shown in FIGS. 2 to 4, an opening communicating with the side surface near the end face 16 to the through hole 18 may be used. Further, such a ventilation path may be provided in the vicinity of the end surface 16 at a side surface position that does not overlap the fusible body passage groove 20.

Further, although the shape of the main body of the chip fuse described with reference to FIG. 1 as a preferred embodiment of the present invention is a prismatic body, the present invention is not limited to this, and any shape such as a cylindrical body may be used. It may be a columnar body. Further, the outer shape of the conductive terminal is not limited to the rectangular shape as shown in FIG. 1 and may be a circular shape, as long as the recess of the conductive terminal fits in the main body without a gap. .

FIG. 5 is a component block diagram of another embodiment of the chip fuse of the present invention having a structure in which the fusible body through groove extends to the other end surface. The chip fuse shown in FIG. 5 differs from the embodiment of FIG. 3 in that the fusible body through groove extends to the other end face in order to facilitate the manufacture of the small ceramic body 10. Other points are the same.

[0016]

Since the present invention is constructed as described above, it has the following effects. That is, since the air vent opening that communicates with the through hole is formed on the side surface near the end surface of the main body, when the heated conductive terminal is fitted from the end surface, the air that has been heated and expanded in the through hole is discharged from the opening. Since it can be discharged, the preliminary solder that electrically connects the concave portion of the conductive terminal and the fusible body is not pushed out by the expanded air from between the inner surface of the concave portion of the conductive terminal and the outer peripheral surface of the main body. Therefore, electrical connection between the conductive terminal and the fusible body is ensured, and the yield is improved and the reliability of the chip fuse is increased.

[Brief description of drawings]

FIG. 1 is a perspective view of a finished chip fuse of the present invention.

FIG. 2 is a perspective view of the main body 10 shown in FIG.

FIG. 3 is a component configuration diagram of the chip fuse shown in FIG. 1 before assembling.

4 is a cross-sectional view of the chip fuse after the components of the chip fuse shown in FIG. 3 are assembled, as seen from a surface including a fusible body 14, a fusible body through groove 20 and an air vent notch 26. FIG.

FIG. 5 is a structural diagram of another embodiment of the chip fuse of the present invention having a structure in which a fusible body through groove extends to the other end surface.

FIG. 6 is a component configuration diagram of a conventional chip fuse.

[Explanation of symbols]

10: body, 12: conductive terminal, 14: fusible body, 16:
End face, 18: through hole, 20: fusible material passage groove, 22: concave portion, 24: preliminary solder, 2
6: Air vent notch

Claims (4)

[Scope of utility model registration request] 1. A main body made of a heat-resistant insulating material and having a shape of a columnar body, having a through hole penetrating between both end faces in the longitudinal direction, and the penetrating hole on the outer peripheral surface of at least one end face of the both end faces. A main body having an opening communicating with the hole, and a fusible body stretched over the through hole, each end of which extends along the both end surfaces and the outer peripheral surface in contact therewith. The fusible body is stopped, and the recessed portions are fitted to the outer peripheral surfaces of the both end surfaces, and when fitted, the recessed portion and the end portion of the fusible body are electrically connected via preliminary solder. And a pair of conductive terminal portions in which the recess covers the opening of the main body. 2. The chip fuse according to claim 1, wherein the opening of the main body is a notch formed in the end surface. 3. The chip fuse according to claim 1, wherein the opening is formed on the outer peripheral surface of the both end surfaces. 4. The chip fuse according to claim 1, wherein a fusible body through groove is formed on the outer peripheral surfaces of both end surfaces of the main body, and the end portion of the fusible body is locked in the fusible body through groove. A chip fuse in which an opening is arranged at a position different from that of the fusible body through groove.