JPH06310387A - Solid electrolytic capacitor provided with fuse and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a solid electrolytic capacitor which is provided with a built-in fuse and appropriate for mass-production, enhanced in reliability of fuse connection and manufacturing yield, and set free from defects caused by a fuse wire. CONSTITUTION:An insulating resin layer 3 is formed on a cathode layer 1a of a solid electrolytic capacitor element 1, the surface of the insulating resin layer 3 is roughened by laser rays, catalyst is applied, and a metal plating 5 is provided for the formation of a fuse 5a. The fuse 5a is connected to the cathode layer 1a and the cathode terminal 7 with a carbon layer 4 and a silver paste 8 respectively. By this setup, a fuse can be formed by laser matching without using a fuse wire, so that a fuse is prevented from being disconnected due to a stress induced by vibrations or the like. As a solid electrolytic capacitor provided with a fuse of this design is formed through processes which can be carried out at the same time, it is suitable for mass production and can be assembled in the same production line with a capacitor with no built-in fuse.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor with a fuse and a method for manufacturing the same, and more particularly to a solid electrolytic capacitor with a fuse which is constructed without using a fuse wire and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, solid electrolytic capacitors are used in various electronic circuits, and it is an advantage that the failure rate is small. However, once a failure occurs, a short circuit often occurs. When a large short-circuit current flows in such a case, the capacitor element may generate heat and burn out.

In order to prevent the capacitor element from being burnt out in the event of a failure due to this excessive short-circuit current and to protect the peripheral circuit constituent elements, it is necessary to release the capacitor element from a short circuit.

Conventionally, a solid electrolytic capacitor having a built-in fuse is generally used for this purpose. Such a solid electrolytic capacitor is called a solid electrolytic capacitor with a fuse.

FIG. 4 is a perspective view showing the structure of a conventional solid electrolytic capacitor with a fuse. An anode lead 2, a cathode layer 1 a, and a cathode terminal 7 are bonded to the capacitor element 1 with an insulating adhesive 12. Then, the fuse wire 5b is connected to the cathode layer 1a and the cathode terminal 7 with the solder 11, and the two are bridge-connected, and the whole is covered with the exterior resin 10.

[0006]

The conventional chip-type solid electrolytic capacitor with a fuse described above has a structure in which the cathode layer and the cathode terminal are electrically connected by a fuse wire. Therefore, it has the following drawbacks. (1) The fuse wire and the capacitor element are directly connected. Therefore, when an overcurrent flows and the fuse wire heats up, this heat indirectly melts the solder in the cathode layer and causes thermal expansion to destroy the exterior resin.
(2) An insulating adhesive is used to bond the cathode layer and the cathode terminal of the capacitor element. However, since the cathode layer and the cathode terminal of the capacitor element are fixed to each other, mechanical and thermal stress may be applied to the capacitor element during the molding of the exterior resin and the immersion of the solder after the exterior package, which may deteriorate the electrical characteristics. there were. (3) Depending on the connection state of the anode lead and the anode terminal and the connection state of the fuse wire, the capacitor element and the cathode terminal are likely to be exposed to the outside of the exterior resin, and the capacitor element itself has a large size depending on the capacity and the counter voltage. Since the shape is not always constant, the position where the fuse wire and the cathode layer are connected by soldering is not constant, and it is difficult to automatically solder the fuse wire.

The object of the present invention is to eliminate the drawbacks due to the use of fuse wires, improve the reliability and yield of fuse connection,
It is to provide a solid electrolytic capacitor with a fuse suitable for mass production.

[0008]

A solid electrolytic capacitor with a fuse according to a first aspect of the present invention is a solid electrolytic capacitor element, an anode terminal connected to an anode lead derived from the solid electrolytic capacitor element, and the solid electrolytic capacitor. In a fused solid electrolytic capacitor in which a cathode layer and a cathode terminal of an electrolytic capacitor element are connected by a fuse, an insulating resin is applied to one side surface of the cathode layer of the capacitor element, and a carbon layer is formed on the cathode layer on the opposite surface of the anode lead. A metal plating layer and a silicon layer are sequentially deposited, and a part of the metal plating layer and the cathode terminal are connected by a conductive adhesive, and a fuse is formed by metal plating on the insulating resin surface. Is formed.

The method for manufacturing a solid electrolytic capacitor with a fuse according to a second aspect of the present invention includes a step of applying an insulating resin to one side surface of the solid electrolytic capacitor element, and a shape for forming a fuse on the insulating resin surface. Laser roughening the surface, dipping and applying 4 catalyst solutions containing metal powder,
A step of dipping and applying carbon on one surface of the cathode layer of the solid electrolytic capacitor element; a step of electrolessly plating the roughened fuse forming portion and the carbon layer to form a plating layer; and applying a silicon resin And a step of connecting the anode lead and the anode terminal, and a step of connecting a part of the plating layer and the cathode terminal with a conductive adhesive.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a plan view and a side cross-sectional view of a chip type solid electrolytic capacitor with a fuse according to an embodiment of the present invention, in which an upper portion of an exterior resin is peeled off, and FIG. 2 is a fuse formation according to an embodiment of the present invention. FIG. 3 is a plan view after processing into a shape to be formed, and FIG. 3 is a plan view illustrating a step of forming a fuse which is an embodiment of the present invention.

In FIG. 1, in a state where a part of the anode lead 2 is embedded in a metal powder having a valve action such as tantalum or aluminum, press molding is performed to form an anode body, and the anode body is vacuum-sintered. The capacitor element 1 (hereinafter abbreviated as element 1) is obtained by anodizing and then forming a cathode layer 1a by sequentially depositing a manganese dioxide layer, a carbon layer, and a silver paste layer on the anodized film.

In FIG. 1, a 5 μm thick metal plating layer 5 formed on a water-repellent insulating resin 3 applied on one surface of the element 1.
A carbon layer 4 is formed on the side of the opposite surface in which the anode lead 2 is embedded, including a part of the above, and the anode layer 1a of the element 1 and the metal plating layer 5 are electrically connected. Further, a silicon resin 6 is applied to the carbon layer 4 to insulate it from the cathode terminal 7.

A portion of the metal plating 5 which is conductively connected to the cathode terminal 7 and the silver paste 8 and the connecting portion of the carbon layer 4 are bridge-connected by the metal plating 5 having a width of about 0.2 mm to form the fuse 5a. Next, the anode reed 2 and the anode terminal 9 are connected to each other by welding or the like, and are covered with the mold resin 10.
It is possible to form a solid electrolytic capacitor with a fuse, which is the first embodiment of the present invention shown in FIG.

The manufacturing method of the first embodiment will be described below. In FIG. 1, a water-repellent insulating resin 3 is applied to one side surface of the element 1 and dried. The surface of the insulating resin 3 is ground by a laser (not shown) so that the fuse 5a becomes I-shaped, and the rough surface 3a is coated with a catalyst solution containing a minute amount of metal powder as shown in FIG. a). 2B and 2C are modifications of FIG. 2A.

In FIG. 3A, the carbon layer 4 is formed by dip coating on the surface facing the anode lead 2 including a part of the rough surface 3a described above, and the entire element 1 is metal-plated 5. b)
The fuse circuit shown in is formed.

In FIG. 3 (c), a part of the fuse circuit and the carbon layer 4 are dip-coated with a silicon resin 6, and then the metal plating layer 5 and the cathode terminal 7 are connected with a silver paste 8 to make the anode lead 2 and the anode. If the terminal 9 is connected by welding, etc., and the anode / cathode terminal is molded by resin transfer coating, the first
The chip-type solid electrolytic capacitor with a fuse, which is the embodiment of FIG.

Next, a second embodiment will be described. First
In the embodiment described above, the metal plating layer 5 was connected to the cathode terminal 7 with the silver paste 8 to form the fuse circuit. However, in this embodiment, a solder layer (not shown) having the same shape is formed on the metal plating layer 5. The same effect can be obtained by forming and connecting to the cathode terminal 7 by soldering. The present embodiment is characterized in that the connection strength with the cathode terminal is obtained, and that solder is used to form solder of about 0.1 mm in the fuse portion 5a and functions as a thermal fuse.

Next, in order to confirm the effect of the present invention, the result of the fuse blowing characteristic of the solid electrolytic capacitor with a fuse of the present invention will be described. The samples used were 100 according to the first embodiment of the present invention and 100 for the conventional example for comparison.
It is 0. An overcurrent was applied to these samples to observe the blown state of the fuse. The results are shown in Table 1. In the present example, none of the mold resins 10 was broken between the time the fuse 5a generated heat and the time it was blown. Although not shown in the table, none of the capacitor elements 1 burned out, and all of them functioned reliably as safety devices.

[0019]

[Table 1]

It is considered that this is because the fuse is blown at a current value of 60% or less as compared with the conventional case by forming the fuse by metal plating having a thickness of several μm as compared with the conventional fuse wire made of solder. In this embodiment, the fuse circuit has an I shape, but it is needless to say that the same effect can be obtained by using the crank shape or the zigzag shape shown in FIGS. 2B and 2C. Also for the dip type, the same effect can be easily obtained by changing the fuse shape, and the dip type solid electrolytic capacitor can be obtained.

[0021]

As described above, according to the present invention, since the fuse circuit is formed by metal plating on the cathode layer of the element, (1) there is no handling of the fuse wire, so that automation is easy, and (2) Since the shape of the fuse can be freely processed by the laser, it is possible to combine the fuse characteristics for each product type. (3) After the fuse circuit is formed, the product assembly process can be shared with mass production lines that do not have a built-in fuse. Has the effect of.

[Brief description of drawings]

FIG. 1 is a plan view and a side sectional view of a chip type solid electrolytic capacitor with a fuse, which is an embodiment of the present invention, in a state where an outer layer resin upper portion is peeled off.

FIG. 2 is a plan view of an element showing the order of steps for explaining the formation of a fuse shape according to an embodiment of the present invention.

FIG. 3 is a plan view of an element, which is shown in order of steps for explaining fuse formation in an example of the present invention.

FIG. 4 is a perspective view and a sectional view of a conventional chip solid electrolytic capacitor with a fuse.

[Explanation of symbols]

 1 Capacitor Element 1a Cathode Layer 2 Anode Lead 3 Insulating Resin 3a Rough Surface 4 Carbon Layer 5 Metal Plating Layer 5a Fuse Part 5b Fuse Wire 6 Silicon Resin Layer 7 Cathode Terminal 8 Silver Paste 9 Anode Terminal 10 Mold Resin 11 Solder Layer 12 Insulation adhesive

Claims (2)

[Claims] 1. A solid electrolytic capacitor element, an anode lead derived from the solid electrolytic capacitor element, an anode terminal connected to the anode lead, a cathode layer and a cathode terminal of the solid electrolytic capacitor element are connected by a fuse. In the solid electrolytic capacitor with a fuse, an insulating resin layer applied to one side surface of the cathode layer of the capacitor element, a carbon layer formed on the cathode layer opposite to the anode lead lead-out surface of the capacitor element, An insulating resin layer and a metal plating layer sequentially deposited on the carbon layer, a silicon resin layer, and a cathode terminal connected to a part of the metal plating layer with a conductive adhesive, A solid electrolytic capacitor with a fuse, characterized in that the fuse is composed of a metal plating layer formed on the surface. 2. A step of applying an insulating resin to one side surface of the solid electrolytic capacitor element, and a surface roughening by laser of the insulating resin surface into a shape for forming a fuse, and dipping / application in a catalyst solution containing metal powder. A step of dipping and applying carbon to one surface of the cathode layer of the solid electrolytic capacitor element, a step of electrolessly plating the roughened fuse forming portion and the carbon layer, and forming a plating layer, A fuse including a step of applying a silicone resin, a step of connecting the anode lead and the anode terminal, and a step of connecting a part of the plating layer and a cathode terminal with a conductive adhesive. Manufacturing method of solid electrolytic capacitor.