JPH0444411B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solid electrolytic capacitor with a fuse, and particularly to a structure in which a fuse is built into the solid electrolytic capacitor.

[Conventional technology]

Generally, solid electrolytic capacitors are used in various electronic circuits, and their failure rate is low, 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. When a failure occurs due to this excessive short-circuit current, it is necessary to change the failure mode from short circuit to open in order to protect the circuit components. There is. As a conventional technique, for example, there is a solid electrolytic capacitor with a built-in fuse as disclosed in Japanese Patent Publication No. 58-21816.

[Problem that the invention seeks to solve]

The conventional solid electrolytic capacitor with a fuse described above has a metal plate 10 and a fuse 7 connected between the capacitor element 1 and the cathode external terminal 4, as shown in FIG.

(b) Therefore, capacitor element 1 and cathode external terminal 4
There are three connections between the two, which requires a large amount of connection work, and the connection area is small, which poses a problem in connection reliability.

(b) The fuse 7 is located in the cavity 12 between the heat insulators 11 disposed facing each other, and the insulation body 11 is sandwiched between the cathode external terminal 4 and the metal plate 10 and soldered to maintain an airtight state. However, the cavity 12 may be filled with solder due to solder dripping during soldering, or airtightness cannot be achieved due to insufficient amount of solder, and the exterior resin 9 may enter during the resin exterior process in the subsequent process. There are drawbacks such as.

[Means for solving problems]

The solid electrolytic capacitor with a fuse of the present invention is
A conductor layer disposed facing each other on one side of an insulating plate with a band-shaped insulator section in the middle, a fuse that traverses a recess provided in the center of the insulator section and bridges and connects the conductor layers; The present invention is characterized in that a printed wiring board to which an insulating plate having a concave portion for accommodating the fuse is bonded to the surface in contact with the fuse is inserted and connected between the external terminal of the solid electrolytic capacitor element, and an insulating exterior is formed.

〔Example〕

Hereinafter, the present invention will be explained with reference to the drawings. FIG. 1 is a side sectional view of one embodiment of the present invention. For example, a solid electrolytic capacitor element (hereinafter abbreviated as element) has a cathode part as the outermost layer, by anodizing an anode body made of a valve metal such as tantalum, and sequentially depositing a manganese dioxide layer, a carbon layer, and a silver base layer thereon. Form 1. The anode lead 2 planted on this element 1 and the anode external terminal 3 are connected by means such as welding. Next, the end of the cathode external terminal 4 and the end of the printed wiring board 5 containing a built-in fuse (described later) are connected by soldering or the like, and then the printed wiring board 5 and one side of the cathode of the element 1 are connected by soldering or the like. After that, the capacitors are insulated and coated with a sheathing resin 9 such as epoxy by transfer molding or the like, and the anode and cathode external terminals 3 and 4 are bent and formed into a cross-sectional shape to form a solid electrolytic capacitor with a fuse. .

FIGS. 2 and 3 are perspective views illustrating the structure and manufacturing process of the printed wiring board 5 with built-in fuses and the cathode external terminal 4 shown in FIG. 1.

As shown in FIG. 2, a rectangular insulating plate made of glass-epoxy material coated with copper on one side is etched to form a printing arrangement board 5 having a step-shaped copper foil removal pattern 5a. A circular or square recess 6 is provided approximately in the center of the copper foil removal pattern 5a of the printed wiring board 5 by drilling with a drill or the like.
Next, solder is applied to the upper and lower copper foil portions of the printed wiring board 5 by means of soldering or the like to form conductor layers 5b and 5c. Next, a fuse 7 made of a fine aluminum wire whose outer circumferential surface is covered with palladium, for example, by a cladding is made to cross over the recess 6 and connected to the conductor layers 5b and 5c by soldering or the like. Next, an insulating plate 8 made of epoxy resin or the like is provided with a recess 8a having a larger area than the recess 6 of the printed wiring board 5 in the center, and the fuse 7 is housed in the recess 8a of the printed wiring board 5 using an adhesive and sealed. Install it as shown. Next, as shown in FIG. 3, the printed wiring board 5 with the insulating plate 8 attached thereto is connected to the cathode external terminal 4 as described above.

This insulating plate 8 hollows out the area around the fuse 7 and seals it to prevent heat dissipation to the surrounding area when an overcurrent flows through the fuse 7 and generates heat, and also when injecting the exterior resin 9 in the mold exterior process in the later process. Protect fuse 7 from impact. Since the insulating board 8 is connected to the printed wiring board 5 using an insulating adhesive such as epoxy resin, it is sufficient that the hollow recesses 6 and 8a are not completely filled even if the amount of solder is increased to a certain extent, compared to the conventional method of soldering. When sealed with a large amount of solder, solder conduction occurs inside the cavity 12 and the effect of the fuse is lost.On the other hand, if there is a small amount of solder, the seal is not sealed and the exterior resin infiltrates.In contrast, in the present invention, the adhesive It becomes easier to adjust the amount.

〔Effect of the invention〕

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

() Connection man-hours are reduced, the area of the connection part is increased, and connection reliability is improved.

() Since the fuse can be reliably installed in an airtight state covered with an insulating plate, the operational reliability of the fuse is increased and it is easier to protect it from the exterior resin.

[Brief explanation of drawings]

FIG. 1 is a sectional side view of a solid electrolytic capacitor with a fuse according to the present invention, and FIGS. 2 and 3 are perspective views showing the manufacturing process of the printed wiring board with a fuse, which is the main part of the present invention shown in FIG. FIG. 4 is a side sectional view of a conventional solid electrolytic capacitor with a fuse. 1: (solid electrolytic capacitor) element, 2: anode body lead, 3: anode external terminal, 4: cathode external terminal,
5: Printed wiring board, 6: Recess, 7: Fuse, 8:
Insulating plate, 9: Exterior resin, 10: Metal plate, 11: Heat insulator, 12: Cavity.

Claims (1)

[Claims] 1. A conductive layer arranged on one side of an insulating plate to face each other with a band-shaped insulating section in the middle, and a fuse that crosses a recess provided in the center of the insulating section and connects the conductive layer by bridging. and a printed wiring board having an insulating plate bonded thereto having a concave portion for accommodating the fuse on the surface that contacts the fuse is inserted and connected between the element of the solid electrolytic capacitor and the external terminal, and an insulating exterior is provided. solid electrolytic capacitor.