JPH1012492A - Manufacture of chip-type solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of a chip-type solid electrolytic capacitor which is small in size, large in capacity and low in cost and has a simple outer covering construction. SOLUTION: An anode lead 2 which is stood on a capacitor element 1 made of valve action metal is electrically and mechanically connected beforehand to a chain lead 6A which is inserted into an encapsulation resin case 10 made of thermoplastic resin. Anode protecting resin 4 is applied to the drawing-out part of the anode lead 2 and resin 5 for fixing the encapsulation resin case 10 temporarily is also applied simultaneously. A dielectric film layer, a solid electrolyte layer and a cathode lead layer 3 are successively formed on the circumferential surface of the capacitor element 1 which is then enclosed in the encapsulation resin case 10. An outer cathode layer 9A which consists of a conductive paste layer 7, a nickel plating layer 8 and a solder plating layer 9 is successively formed on the cathode lead layer 3 exposed from the opening of the encapsulation resin case 10. The chain lead 6A which is drawn out of the encapsulation resin case 10 is cut and bent to form an outer anode terminal 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a leadless chip type solid electrolytic capacitor used in small electronic equipment and suitable for surface mounting on a printed circuit board or the like.

[0002]

2. Description of the Related Art A specific example of a chip type solid electrolytic capacitor will be described below with reference to FIG. In the figure, reference numeral 14 denotes an anode lead 1 of a metal wire having a valve action such as tantalum or titanium.
A capacitor element 16 which is an anode body formed by pressing metal powder having the same valve action into a rectangular parallelepiped shape and sintering the outer periphery of one end of the element 5, and 16 is welded to the tip of an anode lead 15 protruding from the capacitor element 14. An external anode lead 17 is a cathode extraction layer formed on the peripheral surface of the capacitor element 14 via an oxide film layer (dielectric film layer) and a semiconductor layer (solid electrolyte layer), and 18 is a part of the outer periphery of the cathode extraction layer 17. An external cathode lead adhered by a conductive adhesive 19 such as an Ag paste, and 20 is a molded exterior resin material for exposing the front end portions of the external positive cathode leads 16 and 18 to seal a main portion. Then, external positive cathode leads 16, 1
No. 8 is manufactured by bending and forming along the end surface and the back surface of the exterior resin material 20 by being led out from two opposite end surfaces of the exterior resin material 20.

[0003]

In the above-described method for manufacturing a chip-type solid electrolytic capacitor, the external positive and negative electrode leads 16 and 18 are led out to the outside from two opposite ends of the exterior resin material 20 so that the exterior resin material 20 is The junction between the anode lead 15 and the external anode lead 16 which is bent along the end face and the rear surface and protrudes from the inside of the capacitor element 14, and the junction between the cathode lead layer 17 of the capacitor element 14 and the external cathode lead 18 It is necessary to cover the portion with the exterior resin material 20, which restricts the volume of the capacitor element 14, lowers the volume efficiency, and limits the reduction in size and weight. Further, there are disadvantages such as characteristic loss due to the resistance of the external cathode lead 18 and high cost due to an increase in the number of parts.

[0004]

According to a method of manufacturing a chip-type solid electrolytic capacitor of the present invention, an exterior resin case using a thermoplastic resin is inserted into a chain lead which is vertically mounted on a metal strip and later becomes an external anode terminal. And temporarily fixing the anode lead made of a valve action metal planted on an anode body made of a valve action metal to a chain lead, and an anode protection resin and an exterior resin case around an anode lead lead-out portion. Simultaneously forming a resin for temporarily fixing the anode body, sequentially forming a dielectric coating layer, a solid electrolyte layer, and a cathode extraction layer on the peripheral surface of the anode body, enclosing the anode body in a resin case, and Forming an external cathode terminal composed of a conductive paste layer, a nickel plating layer, and a solder plating layer, and cutting and bending a chain lead derived from a resin case to form an external anode terminal And a degree, characterized by using a chain leads to the series of work steps is an external anode terminal.

[0005] According to the above construction, a part of the cathode extraction layer of the anode body is exposed by the partial outer case by the outer resin case,
By applying a conductive paste of silver or carbon to this portion and plating the surface with nickel and solder, electric loss (ESR) due to external electrode terminals can be reduced. Further, by manufacturing a series of manufacturing modes by a chain lead method, material costs and processing costs can be reduced. In addition, the cathode leadless structure enables lightness, thinness, and miniaturization.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a chip-type solid electrolytic capacitor manufactured by the manufacturing method of the present invention. In the figure, 1 is a capacitor element made of a sintered body of metal particles such as tantalum or titanium, 2 is an anode lead made of a tantalum metal wire, and 3 is an electrically conductive layer on the peripheral surface of the capacitor element 1 via an oxide film layer and a semiconductor layer. 4 is an anode protection resin, 5 is an outer resin case temporary fixing resin, 6 is an external anode terminal formed by cutting and bending a chain lead 6A, 7 is a silver or carbon conductive paste. Layer, 8 is a nickel plating layer, 9 is a solder plating layer,
9A is an external cathode terminal having a three-layer structure, 10 is an exterior resin case using a thermoplastic resin, and 12 is a sealant.

Hereinafter, a method of manufacturing the above-mentioned chip type tantalum solid electrolytic capacitor will be described. First, as shown in FIG. 2, an exterior resin case 10 made of a thermoplastic resin is inserted into a chain lead 6A fixed to a large number of metal strips 11 and temporarily fixed. Next, a capacitor element 1 obtained by pressing a metal powder having the same valve action into a rectangular parallelepiped shape and sintering it on the outer periphery of one end of an anode lead 2 of a metal wire having a valve action such as tantalum or titanium is shown in FIG. The capacitor element 1 is fixed via the anode lead 2 at the tip of a plurality of chain leads 6A fixed to the metal strip 11 as shown. Next, as shown in FIG. 3, the anode protection resin 4 is formed of a UV resin or the like, and at the same time, the temporary fixing resin 5 is formed so that the exterior resin case 10 does not cover the capacitor element 1.

Next, in a state where the capacitor element 1 is fixed to the chain lead 6A, a cathode extraction layer 3 is formed on the peripheral surface thereof with a carbon paste, a silver paste or the like via an oxide film layer and a semiconductor layer. Next, the exterior resin case 10 is put on the capacitor element. A conductive paste layer 7 of silver or carbon is formed by dipping on the capacitor element exposed from the opening of the exterior resin case 10,
A nickel plating layer 8 is formed on the surface by electroless nickel plating. Further, in order to improve the solderability at the time of mounting the product, a solder plating layer 9 is formed on the surface by solder plating, and an external cathode terminal 9A having a three-layer structure is obtained to obtain a product form as shown in FIG. Next, as shown in FIG. 4, the exterior resin case 10 of the chain lead 6A is used to secure airtightness.
Sealant 12 made of epoxy resin or the like in insertion hole 10a
Is applied and cured by heat. Next, the chain lead 6A led out from the opposite end face is cut, pressed, and bent along the side and back surfaces of the exterior resin case 10, thereby forming the external anode terminal 6 as shown in FIG. I do.

By using the exterior resin case 10 made of a thermoplastic resin as in the above method, the thermal stress and the shrinkage stress at the time of curing caused by the conventional thermosetting resin are eliminated. Furthermore, since the exterior method is formed by covering the exterior resin case 10 inserted in the chain lead 6A,
The exterior process can be performed more efficiently than before. In addition, since the distance between the cathode terminals can be shortened by the cathode structure as shown in FIG. 1, it is possible to increase the size efficiency and to increase the size and the capacity by increasing the volume efficiency. Further, by using a chain lead in these series of manufacturing modes, the processing method is simplified, and the processing cost can be reduced. Further, from the viewpoint of electrical characteristics, since the structure has no external cathode terminal, external loss (ESR) can be reduced.

[0010]

As described above, the present invention improves the volumetric efficiency of the capacitor element as an internal element by employing an external cathode leadless structure with a partial outer case made of an outer resin case, and realizes a light, thin, short, small, and large capacity. This is also effective in reducing the loss (ESR) due to external resistance in electrical characteristics. In addition, by using the chain lead method for a series of manufacturing modes, the manufacturing method is simplified and the processing cost is also reduced.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing a manufacturing mode of a chip-type solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 3 is a perspective view showing a manufacturing mode of a chip-type solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 4 is a perspective view showing a manufacturing mode of a chip-type solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 5 is a perspective view showing a manufacturing mode of a chip-type solid electrolytic capacitor according to an embodiment of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor element (anode body) 2 Anode lead 3 Cathode extraction layer 4 Anode protection resin 5 Temporary fixing resin 6 External anode terminal 6A Chain lead 7 Conductive paste layer 8 Nickel plating layer 9 Solder plating layer 9A External cathode terminal 10 Exterior resin case 10a Insertion hole 11 Metal strip 12 Sealant

Claims (3)

[Claims] 1. A step of inserting and temporarily fixing an exterior resin case made of a thermoplastic resin to a chain lead suspended from a metal strip, and attaching an anode lead planted on an anode body made of a valve action metal to the chain lead. A step of fixing, a step of simultaneously forming an anode protection resin and a resin for temporarily fixing an exterior resin case around an anode lead lead-out portion, and a dielectric coating layer, a solid electrolyte layer, and a cathode extraction layer on a peripheral surface of the anode body. Sequentially forming,
A step of enclosing the anode body in a resin case, a step of sequentially forming an external cathode terminal composed of a conductive paste layer, a nickel plating layer, and a solder plating layer, and cutting and folding a chain lead derived from the resin case. Forming a solid electrolytic capacitor by bending and forming an external anode terminal. 2. The method according to claim 1, wherein the conductive paste layer of the external cathode terminal is formed of graphite paste. 3. The method according to claim 1, wherein the conductive paste layer of the external cathode terminal is formed of a silver paste.