JPH0551165B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a chip-type capacitor with a fuse, and particularly to a structure in which a fuse is built into an exterior resin.

[Conventional technology]

Solid electrolytic capacitors are generally used in various electronic circuits, and have a low failure rate, but in the event of a failure, the failure mode is often short-circuit failure, and when a large short-circuit current flows, the capacitor element heats up and burns out. It may even lead to. In the event of a failure due to short-circuit current at this temperature, it is necessary to change the failure mode from short-circuit to open in order to protect the circuit components, and the commonly known method is to use a fuse. ing.

As prior art, the perspective view of FIG. 5 and the perspective view of FIG.
As shown in the side cross-sectional view of the figure, the external cathode terminal 1
An insulator 30 is inserted between 5 and the cathode layer 25 for insulation, and a fuse 35 is connected to the external cathode terminal 1 by soldering.
5 and the cathode layer 25, and the exterior resin 4
There is a structure that has an insulated exterior and is bent along this wall surface.

[Problem that the invention seeks to solve]

The conventional fuse-equipped chip type solid electrolytic capacitor described above has the following drawbacks because the fuse is connected to the cathode layer side.

(1) Since the fuse and capacitor element are close to each other, the fuse will blow when an overcurrent flows.
This thermal insulation indirectly melts the solder on the cathode layer, causing thermal expansion, breaking the exterior resin and blowing it out, which can short-circuit other wiring circuits and cause secondary disasters, or directly. This may cause burnout of the capacitor element, resulting in even more serious disaster.

(2) When connecting a fuse, since the cathode layer of the capacitor element and the cathode terminal are insulated with resin, there is a risk of a short circuit when the resin hardens, so please insulate the cathode layer or cathode terminal in advance. It is necessary to keep it. Furthermore, the surface of the cathode layer is not uniform in shape, including variations in the size of the capacitor element itself, and when soldering is performed automatically, it becomes extremely difficult to set conditions, making the process complicated.

(3) There is a strong demand for chip-type solid electrolytic capacitors to be smaller in size and larger in capacity, so it is necessary to increase the size of the capacitor element to be accommodated and to make the outer resin wall thickness as thin as possible. However, in order to connect a fuse to the cathode layer, the exterior resin must be made thick to ensure space for the connection and the fuse itself and to prevent solder from blowing out, which reduces the volumetric efficiency of the capacitance.

[Originality of invention]

The conventional chip-type solid electrolytic capacitor with a fuse described above has a structure in which an insulator is inserted between the external cathode terminal and the cathode layer on the cathode side to insulate the cathode layer, and a fuse is connected. The chevron-shaped anode terminal that connects to the anode wire and the protruding external anode terminal have a fuse that connects to the anode side inside the exterior resin, and the chevron-shaped anode terminal has a corner of the exterior resin with chamfered corners. It has an original content in that it is separated by a wall.

[Means for solving problems]

An object of the present invention is to eliminate such conventional drawbacks and provide a solid electrolytic capacitor with a fuse that has highly reliable electrical characteristics and high volumetric efficiency.

According to the present invention, in a chip-type solid electrolytic capacitor in which the lead-out portions of the anode and cathode terminals facing each other with the capacitor element in between are bent along the wall surface of the exterior resin, the chevron-shaped anode is connected to the anode wire of the capacitor element. The terminal and the external anode terminal drawn out from the exterior resin have a fuse for bridging connection inside the exterior resin, and the cut surface of the chevron-shaped anode terminal is exposed on a wall surface of the exterior resin with chamfered corners. A chip-type solid electrolytic capacitor with a fuse is obtained.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

1 is a perspective view showing the internal structure of a first embodiment of the present invention, FIG. 2 is a side sectional view of FIG. 1, and FIG. 3 is a front sectional view of FIG. 1.

First, nickel, iron (58%) - nickel (42
%) alloy (so-called 42 alloy) is prepared, and as shown in FIG. A connected lead frame 6 is formed.

Next, an anode body made of a valve metal such as tantalum is anodized, and a manganese dioxide layer, a carbon layer, and a silver paste layer are sequentially deposited on the anode body, and a solid electrolytic capacitor element ( A capacitor element (hereinafter abbreviated as a capacitor element) 1 is formed. The anode wire 2 connected to the capacitor element 1 in a raised manner is connected to a part of the chevron-shaped anode terminal 3 by means such as welding. On the other hand, the capacitor element 1 is adhered to the conductive adhesive 7 which has been previously applied in a certain amount to the cathode terminal 5 having the stepped portion, and is dried and fixed. Thereafter, a fuse 8 is soldered between the chevron-shaped anode terminal 3 and the external anode terminal 4, or wire bonding or the like is used to connect the fuse 8 to secure both ends of the fuse 8. to cover it. Thereafter, it is insulated and exteriorized with an exterior resin 10 such as epoxy resin by means of transfer molding, etc., and the concentric portion of the chevron-shaped anode terminal 3 protrudes from the chamfered portions 10a and 10b at the two corners on the anode side of the exterior resin 10. are separated by the walls of the chamfered portions 10a and 10b of the exterior resin 10, and then the external anode terminal 4 and the cathode terminal 5 are connected to the lead frame 6.
It is then separated and bent along the wall surface of the exterior resin 10 to form the chip-type solid electrolytic capacitor with fuse of the present invention.

When an overcurrent is applied to this finished product, since the fuse is not close to the cathode layer of the capacitor element, accidents such as solder blowout and burnout will not occur until the fuse heats up and is cut. It functions reliably as a safety device, and no secondary disasters occur. In addition, the anode terminal side has better flatness and dimensional uniformity than the cathode layer, so it is easy to connect the fuse, and it is fully possible to apply an automatic wire bonding machine, etc., so the process can be improved. Can be simplified.

In addition, the anode terminal side has more space for connecting the fuse than the cathode side, so there is no need to increase the size of the chip or reduce the size of the capacitor element, and the volumetric efficiency of the capacitance is higher than that of a chip-type solid electrolyte without a fuse. You can get something equivalent to a capacitor. Furthermore, since the anode terminal is separated at the chamfered corners of the exterior resin, even if the anode terminal protrudes slightly and is cut, it can be reliably centered on the automatic mounting machine that automatically mounts it onto the circuit board, etc. A chip-type solid electrolytic capacitor with a fuse can be obtained with improved mounting position accuracy and high mounting probability.

〔Example〕

FIG. 4 is a front sectional view showing a second embodiment of the invention.

In the second embodiment, an L-shaped anode terminal 11 is formed by cutting off one end of the chevron-shaped anode terminal 3 described in the first embodiment, and an external anode terminal is formed inside the exterior resin 10. An L-shaped external anode terminal 12 is formed with one end extended, and is separated at the wall surface of the chamfered portion 10a of the exterior resin 10 as in the first embodiment.

〔Effect of the invention〕

As explained above, the present invention has the following effects.

(1) There is no risk of solder blow-out or burnout accidents, (2) The fuse joining process is simple, (3) It is easy to make it smaller and larger in capacity, and (4) It is compatible with automatic placement machines and has a low attachment probability. A chip-type solid electrolytic capacitor with a high fuse can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the internal structure of a first embodiment of the present invention. 2 shows a side sectional view of FIG. 1, FIG. 3 shows a front sectional view of FIG. 1, FIG. 4 shows a front sectional view of a second embodiment of the present invention, and FIG. 6 is a perspective view showing the internal structure of a conventional chip-type solid electrolytic capacitor with a fuse, and FIG. 6 is a side sectional view of FIG. 5. 1... Capacitor element, 2... Anode wire, 3...
chevron-shaped anode terminal, 4, 20...external anode terminal,
5, 15...Cathode terminal, 6...Lead frame,
7... Conductive adhesive, 8, 35... Fuse, 9
...Elastic resin, 10,40 ...Exterior resin, 10
a, 10b... Chamfered portion, 11... L-shaped anode terminal, 12... L-shaped external anode terminal, 25... Cathode layer, 30... Insulator.

Claims (1)

[Claims] 1. In a chip-type solid electrolytic capacitor in which the lead-out portions of the anode and cathode terminals facing each other across the capacitor element are bent along the wall surface of the exterior resin, the angle-shaped anode terminal connected to the anode wire of the capacitor element and the exterior resin An external anode terminal pulled out from the exterior resin has a fuse for bridging connection inside the exterior resin, and a cut surface of the chevron-shaped anode terminal is exposed on a wall surface of the exterior resin with chamfered corners. A chip-type solid electrolytic capacitor with a fuse.