JPH09171941A - Manufacture of solid electrolytic chip capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inexpensive, thin solid electrolytic chip capacitor in which leak current deterioration is suppressed without resin sealing a capacitor element. SOLUTION: An insulating member 3 and an outer anode terminal 4 are formed simultaneously by insert molding on the anode lead 2 lead-out plane of an anode body 1 planted with the anode lead 2. A dielectric film layer 5, a solid electrolytic layer 6, and a cathode metal layer 7 comprising a graphite layer, a silver paste layer and a solder layer are then formed sequentially on the circumferential surface of the anode body 1. Subsequently, the outer anode terminal 4 are anode lead 2 are irradiated, at the contact point thereof, with a laser beam and welded and then the anode lead 2 projecting from the outer anode terminal 4 is cut off by means of a laser beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a chip type solid electrolytic capacitor, and more particularly to a method for forming external positive and negative terminals.

[0002]

2. Description of the Related Art Conventional chip-type solid electrolytic capacitors are:
As shown in FIG. 6, the external cathode terminal 13 is connected to the capacitor element 11 formed with the dielectric film layer, the solid electrolyte layer, and the cathode metal layer by the conductive adhesive 15 made of silver paste, and the capacitor element is formed. After connecting the anode lead 12 derived from 11 to the external anode terminal 14 by resistance welding, the element 11 and a part of the external positive and negative terminals 14 and 13 are molded with an epoxy-based exterior resin material 16 and molded resin. External positive and negative terminals 14, 1 derived from the material 16
3 was bent and molded.

[0003]

By the way, in the above-mentioned conventional method for manufacturing a chip type solid electrolytic capacitor, since the capacitor element 11 is covered with the resin material 16 such as epoxy resin, the stress from the resin material 16 causes There is a problem that the leakage current of the capacitor increases. In addition, the product becomes thicker by the resin thickness, which hinders the reduction in thickness. Furthermore, since the external cathode terminal 13 is connected by the conductive adhesive 15 made of expensive silver paste, there is a problem in that the cost becomes high and the connection reliability is high.

A method of manufacturing a chip-type solid electrolytic capacitor of the present invention comprises a step of electrically and mechanically connecting an anode lead made of a valve metal, which is erected on an anode body made of a valve metal, to a metal strip. A step of forming an insulating member and an external anode terminal on the lead-out surface of the anode lead, a step of sequentially forming a dielectric coating layer, a solid electrolyte layer, and a cathode metal layer forming an external cathode terminal on the peripheral surface of the anode body, and an anode lead And an external anode terminal are electrically and mechanically connected by laser welding or resistance welding, and then the anode lead is cut, and the insulating member and the external anode terminal are simultaneously formed by insert molding. .

According to the manufacturing method of the present invention, since the cathode metal layer formed on the peripheral surface of the anode body constitutes the external cathode terminal, it becomes unnecessary to newly attach the external cathode terminal. Since an expensive conductive adhesive becomes unnecessary and problems such as poor adhesion are eliminated, the reliability of connection is improved. Further, since the insulating member for insulating the external cathode terminal and the external anode terminal and the external anode terminal are simultaneously formed by insert molding, the step of bending the terminal is eliminated and it is economical. Furthermore, since the capacitor element does not need to be covered with resin, it can be made thin, and the problem that the dielectric film of the element is damaged by the stress of the resin and the leakage current increases is eliminated.

The present invention will be described below by taking a chip type tantalum solid electrolytic capacitor as an example. FIG. 1 is a vertical cross-sectional view of a chip type tantalum solid electrolytic capacitor obtained by the manufacturing method of the present invention. In the figure, 1 is an anode body made of a sintered body of tantalum metal particles, 2 is an anode lead made of a tantalum metal wire, 3 is an insulating member made of a heat-resistant polyimide resin, 4 is an external anode terminal plated with solder, 5 Is a dielectric film raw layer consisting of a tantalum pentoxide film,
Reference numeral 6 is a solid electrolyte layer made of polypyrrole, and reference numeral 7 is a cathode metal layer which is composed of a graphite layer, a silver paste layer and a solder layer and constitutes an external cathode terminal.

A method of manufacturing the above chip type tantalum solid electrolytic capacitor will be described below. Anode body 1 obtained by press-molding tantalum fine powder having a particle size of the order of microns,
The anode lead 2 made of a tantalum metal wire is set up. Next, after sintering in a vacuum furnace set to a temperature of 1500 ° C. or higher, a plurality of anode bodies 1 are fixed to the metal strip plate 8 via anode leads 2 as shown in FIG. Next, the metal strip 8
A cross section shown in FIG. 3 in which the anode body 1 is fixedly attached to the anode body, the insulating member 3 made of heat-resistant polyimide is soldered to the lead-out surface of the anode lead 2 of the anode body 1 and its peripheral portion by insert molding, and the surface thereof. The U-shaped external anode terminal 4 is simultaneously formed. At this time, it is desirable that the thickness of the insulating member 3 be substantially the same as the thickness of the anode pair 1 so that the anode pair 1 and the insulating member 3 are substantially on the same plane.

Next, the anode body 1 adhered to the metal strip plate 8 is immersed in a 0.1 vol% phosphoric acid aqueous solution, and 1 V is applied for 1 minute.
Anodization is performed at a pressure increasing rate of 1 to form a dielectric coating layer 5 made of a tantalum pentoxide coating having a thickness of about 1,000 angstroms. Next, the anode body 1 is immersed in a 20 vol% methanol solution of ferric chloride to impregnate the inside of the anode body 1, and then methanol is evaporated in an oven at a temperature of 50 ° C. Next, the polypyrrole layer 6 which becomes the solid electrolyte layer 6 is formed by immersing in a 10% pyrrole monomer solution flow. Immersion of ferric chloride and pyrrole monomer is about 0.1-0.5 micron inside the anode body 1 and 5 outside the anode body 1.
Until a ~ 20 micron polypyrrole layer 6 is formed 1
It is repeated 0 to 20 times. Next, the polypyrrole layer 6
After forming a graphite layer and a silver paste layer on the above by a known method, the anode body 1 is dipped in a eutectic solder bath at a temperature of 220 ° C. to form a solder layer on the silver paste layer. In this way, the cathode metal layer 7 which is composed of the graphite layer, the silver paste layer and the solder layer and constitutes the external cathode terminal is formed.

Next, a laser beam is applied to a portion where the slit portion 4a of the external anode terminal 4 shown in FIG. 2 intersects with the anode lead 2 so that the external anode terminal 4 and the anode lead 2 are welded and another From the intersection of the slit portion 4a of the external anode terminal 4 and the anode lead 2 by about 5-10
Irradiation is applied to a site separated by a micron, and the anode lead 2 is cut. The welding of the external anode terminal 4 and the anode lead 2 and the cutting of the anode lead 2 are simultaneously performed by two laser beams.

The rated voltage of 16 V produced by the above method,
A voltage of 16 V is applied to 100 chip type tantalum solid electrolytic capacitors having a capacitance of 10 μF, and a result of occurrence of leakage current failure after 1 minute is shown in Table 1. However, the leakage current is 1μ
Those exceeding A were regarded as defective. For comparison, the leakage current was also measured for the capacitor manufactured by the conventional technique. It can be seen that the capacitor obtained according to the present invention has a reduction in leakage current defects as compared with the conventional product.

[0011]

[Table 1]

FIG. 4 is a vertical sectional view of the second embodiment of the present invention. In this embodiment, as shown in FIG.
Since the structure has the tongue piece 40a on the end face portion of 0, there is an advantage that the tongue piece 40a of the external anode terminal 40 and the anode lead 2 can be connected by a resistance welding machine instead of an expensive laser device. is there.

In each of the examples of the present invention, the solid electrolyte layer was formed by oxidative polymerization of poropyrrole, which is one of conductive polymers, by bringing a pyrrole monomer and an oxidant into contact with each other. You may form a manganese dioxide layer by the thermal decomposition method of manganese nitrate which is the technique currently used. However, in this case, the solder plating of the external anode terminal is likely to be melted by the heat of the thermal decomposition and the surface may be oxidized. Therefore, it is preferable to perform the solder plating again after the formation of the manganese dioxide layer.

In the embodiment of the present invention, the chip type tantalum solid electrolytic capacitor has been described as an example, but it goes without saying that it can be applied to a chip type aluminum solid electrolytic capacitor or the like.

As described above, according to the present invention, the capacitor element is not coated with resin and the cathode body portion is also used as the external cathode terminal, and the insulating member and the external anode terminal for insulating the cathode body and the external anode terminal from each other. The following effects can be obtained by simultaneously forming and by insert molding. Since the chip type capacitor can be obtained without coating the capacitor element with resin, the stress received from the resin is eliminated,
Leakage current deterioration can be prevented. The thickness can be reduced by the thickness of the exterior resin. Since the external cathode terminal and the expensive conductive adhesive for attaching the external cathode terminal are not required, not only the cost can be reduced but also the reliability of the connection is improved. Since the insulating member and the external anode terminal can be simultaneously formed by insert molding, the number of work steps can be shortened.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a chip-type solid electrolytic capacitor manufactured by a manufacturing method according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a capacitor element is being fixed to a metal strip plate during the manufacturing method.

FIG. 3 is a perspective view of an external anode terminal used in Example 1 of the present invention.

FIG. 4 is a vertical sectional view of a chip-type solid electrolytic capacitor manufactured by a manufacturing method according to a second embodiment of the present invention.

FIG. 5 is a perspective view of an external anode terminal used in Example 2 of the present invention.

FIG. 6 is a vertical cross-sectional view of a chip-type solid electrolytic capacitor manufactured by a conventional manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode body 2 Anode lead 3 Insulating member 4 External anode terminal 4a Slit part 5 Dielectric film layer 6 Solid electrolyte layer (Polypyrrole layer) 7 Cathode metal layer (External cathode terminal) 8 Metal strip 40 External anode terminal 40a Tongue part

Claims (3)

[Claims] 1. A step of fixing an anode lead made of a valve action metal erected on an anode body made of a valve action metal, and a step of simultaneously forming an insulating member and an external anode terminal on the lead-out surface of the anode lead by insert molding. And a step of sequentially forming a dielectric coating layer, a solid electrolyte layer, and a cathode metal layer forming an external cathode terminal on the peripheral surface of the anode body, and after electrically and mechanically connecting the anode lead and the external anode terminal to the anode. A method of manufacturing a chip-type solid electrolytic capacitor, which comprises the step of cutting the leads. 2. The method for producing a chip type solid electrolytic capacitor according to claim 1, wherein the anode lead and the external anode terminal are connected by laser welding. 3. The method of manufacturing a chip type solid electrolytic capacitor according to claim 1, wherein the anode lead and the external anode terminal are connected by resistance welding.