JPH0590095A - Chip type solid electrolytic capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a downsized high capacity chip type solid electrolytic capacitor, which is excellent in the points of electric properties and volume efficiency and a method for mass-producing the capacitors at a low cost. CONSTITUTION:This capacitor is equipped with armor resin 18, which covers a capacitor element 11a so that it may be exposed in the direction where the phases of the anode lead wire 12 and the cathode part oppose each other, and is provided, at the anode lead face 12a of this armor resin 18, with an anode metallic layer 20 so that it may cover all the faces of the anode lead wire 12 exposed from the armor resin 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip solid electrolytic capacitor and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the number of chip parts has increased rapidly due to the miniaturization of electronic equipment and the progress of surface mounting technology. Even in the chip-type solid electrolytic capacitor, the miniaturization of the chip component itself is required as the size and capacity of the chip solid electrolytic capacitor are increasing.

A conventional chip-shaped tantalum solid electrolytic capacitor will be described below with reference to FIG. In FIG. 4, reference numeral 1 denotes a porous anode body formed by molding and sintering tantalum metal powder which is a valve metal, and a part of an anode lead wire 2 made of a tantalum wire led from the anode body 1 and the anode body 1.
A dielectric oxide film is formed on the entire surface of the anode by anodic oxidation, and an electrolyte layer of manganese dioxide or the like is further formed on this surface. Reference numeral 3 is a Teflon plate attached to the anode lead wire 2, and this Teflon plate 3 is used for forming the electrolyte layer.
It is an insulating plate that prevents manganese nitrate from creeping up and adhering to manganese dioxide. A cathode layer 4 composed of a carbon layer and a silver coating layer is sequentially formed on the electrolyte layer by a dipping method to form a capacitor element 1a. Reference numeral 5 denotes an anode terminal, which is connected to the anode lead wire 2 by welding, and is bent after the exterior resin is formed. Reference numeral 6 denotes a cathode terminal. The cathode terminal 6 is joined to the cathode layer 4 of the capacitor element 1a with a conductive adhesive 7 and is bent after the exterior resin is formed. Reference numeral 8 is an exterior resin that covers the entire capacitor element 1a by molding.

[0004]

However, in such a conventional chip-shaped tantalum solid electrolytic capacitor as described above, mechanically and thermally when the anode lead wire 2 and the anode terminal 5 led from the capacitor element 1a are welded. The stress acts to increase the leakage current, and the space size of the welded portion and the space size for taking out the anode terminal 5 to the outside are large, so that there is a structural size limitation on the size and shape of the capacitor element 1a. Further, the volume ratio of the capacitor element 1a to the volume of the product is as low as 10% in the case of the product having the external dimensions of 3.2 × 1.6 × 1.6 (mm), so that the volume efficiency and economical efficiency of the capacitor are reduced. There was a problem in that. Further, since it is difficult to bend the anode terminal 5 and the cathode terminal 6 along the exterior resin 8, there is a problem that a defective appearance occurs and a stress is applied to the capacitor element 1a to increase a leakage current. ..

The present invention solves the above-mentioned problems of the prior art and is excellent in electrical characteristics and volume efficiency, and can be miniaturized and increased in capacity, and a chip-shaped solid electrolytic capacitor which is inexpensive and can be easily mass-produced. It is an object of the present invention to provide a method for manufacturing a chip-shaped solid electrolytic capacitor that can be manufactured.

[0006]

In order to achieve the above object, a chip solid electrolytic capacitor of the present invention is an anode body made of a valve action metal in which an anode lead wire is embedded so that one end of the anode lead wire is exposed. A capacitor element formed by providing a dielectric oxide film, an electrolyte layer, and a cathode layer on the outside, an exterior resin covering the capacitor element so that the anode lead wire and the cathode portion are exposed in opposite directions, and the exterior resin. Anode metal layer provided on the anode lead-out surface of the resin so as to cover all surfaces of the anode lead-out wire exposed from the exterior resin, and provided on the cathode portion of the exterior resin so as to be electrically connected to the cathode layer. And a cathode metal layer formed thereon.

[0007]

According to the above-mentioned structure, the anode metal layer is formed on the anode lead-out surface of the exterior resin on the anode lead-out wire exposed from the exterior resin. The space for bending the external terminal can be saved, and the volume efficiency of the capacitor can be increased. Further, if the anode metal layer is composed of a metal layer including an electroless plating layer, the anode metal layer serving as the anode terminal and the anode lead wire are connected at the same time, so that a product having excellent productivity can be obtained, and further the exterior Since the anode metal layer is provided so as to cover all the surfaces of the anode lead wire exposed from the resin, the interface between the anode lead wire and the anode metal layer is not affected by mechanical stress or thermal stress during automatic mounting. Physical deterioration is unlikely to occur, and good electrical characteristics can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross-sectional view of a chip-shaped tantalum solid electrolytic capacitor in one embodiment of the present invention, and FIG. 2 shows a state in which a cathode conductor layer is formed on a capacitor element. In FIG. 1 and FIG. 2, 11 is a porous anode body formed by molding and sintering tantalum metal powder which is a valve metal, and a dielectric oxide film is formed on the surface of this anode body 11 by anodic oxidation. An electrolyte layer of manganese dioxide or the like is formed on this surface. In addition, anode lead wire 1
Reference numeral 2 is a tantalum wire, which is led out from the anode body 11. Then, a series of processing steps on the surface of the anode body 11 are performed in a state where the anode lead wire 12 is connected to the metal ribbon 13. Reference numeral 14 is a Teflon plate attached to the anode lead-out wire 12. The Teflon plate 14 is an insulating member that prevents manganese nitrate from crawling up and adhering to the anode lead-out wire 12 when the electrolyte layer is formed on the anode body 11. It is a plate. Further, a cathode layer 15 composed of a carbon layer and a silver coating layer is sequentially laminated on the electrolyte layer of the anode body 11 by a dipping method to form a capacitor element 11a. 16 is a cathode conductor layer, and this cathode conductor layer 16
Is formed on a facing surface 17 of the cathode layer 15 of the capacitor element 11 a that is located on the side opposite to the anode lead-out line 12, and a part of the cathode layer 15 that is an adjacent surface adjacent to the facing surface 17. In this case, the cathode conductor layer 16 is formed by immersing the capacitor element 11a in a viscous liquid of a conductive resin, or by applying an appropriate amount to the capacitor element 11a using a dispenser, followed by drying and curing. Reference numeral 18 denotes an exterior resin. The exterior resin 18 sets the capacitor element 11a in a mold so that the anode lead wire 12 is drawn out to one side, and the entire capacitor element 11a including the cathode conductor layer 16 is resin-covered. As described above, it is formed by transfer molding using an epoxy resin.

3 (a) (b) (c) (d) (e)
(F) and (g) show the manufacturing process of the chip-shaped tantalum solid electrolytic capacitor in one embodiment of the present invention. In FIG. 3 (a), 12a is the anode lead-out surface of the exterior resin 18, and this anode lead-out surface. The surface 12a is located in the vicinity of the anode lead wire 12 in the molded body of the exterior resin 18 and has a concave shape, and the concave shape prevents the anode lead wire 12 from protruding from the external dimensions of the molded body of the exterior resin 18. However, the exposed area can be increased. On the other hand, the cathode conductor layer 16 formed on the facing surface 17 of the exterior resin 18 located on the opposite side of the anode lead wire 12 is longer than the external dimensions of the product. It is longer than the size.

FIG. 3B shows a state in which the molded body of the exterior resin 18 in FIG. 3A is cut or ground to the external dimensions of the product. In FIG. 3 (b), 16a is a cathode lead-out surface, and this cathode lead-out surface 16a is exposed as shown in FIG. 1 by cutting the exterior resin 18 and the cathode conductor layer 16. Anode lead wire 12 and cathode lead surface 1 exposed from the molded body of the exterior resin 18 in FIG.
By subjecting the surfaces of the molded body 6a and the exterior resin 18 to sandblasting, the surface is roughened and the dielectric oxide film of the anode lead wire 12 exposed from the exterior resin 18 molding is removed. ing.

FIG. 3 (c) shows a state in which the anode lead-out wire 12 is separated from the metal ribbon 13 and bent into an L-shape so that the anode lead-out wire 12 fits within the concave shape of the anode lead-out surface 12a. is there.

FIG. 3D shows a state in which the anode lead-out wire 12 is separated from the metal ribbon 13 so that the anode lead-out wire 12 fits within the concave shape of the anode lead-out surface 12a.
Instead of bending it into an L-shape as shown in FIG. 3C, the shape shown in FIG.

FIG. 3 (e) shows the state of formation of the metal layer 19, which is formed of the anode lead wire 12, the anode lead surface 12a, and the molding resin 18 as shown in FIG. The anode metal layer 20 is formed on a part of the surface, and the cathode metal layer 21 is formed on the cathode lead-out surface 16a and a part of the surface of the molded body of the exterior resin 18, and the anode metal layer 20 and the cathode are formed. The metal layer 21 is formed on the entire surface of the anode lead wire 12 exposed from the exterior resin 18 and the anode lead surface 12 first.
The surface of a, the cathode lead-out surface 16a, and the entire surface of the molded body of the exterior resin 18 are subjected to degreasing and pretreatment of applying a palladium catalyst, and then formed by electroless plating. Anode metal layer 20 and cathode metal layer 21 formed by this electroless plating
As the metal, either nickel or copper can be used. By using this electroless plating, it is possible to easily and uniformly form a thin shape even on a complicated shape such as a concave shape, regardless of whether it is a metal surface or a non-metal surface. It is excellent, and the variation in external dimensions can be reduced, and since mechanical and thermal stress is not applied, increase in leakage current does not occur,
It has a very good yield. Further, by setting the thickness of the anode metal layer 20 and the cathode metal layer 21 formed by this electroless plating within the range of 0.5 to 5 μm, the adhesion to the base is excellent, and the amount of material used and the cost are reduced. Can be reduced compared with the conventional manufacturing method. Further, the anode metal layer 20 and the cathode metal layer 2 formed by electroless plating
It is also possible to further form a metal layer by electroplating on 1 to improve the mechanical strength of the anode metal layer 20 and the cathode metal layer 21.

FIG. 3 (f) shows a state in which the anode metal layer 20 and the cathode metal layer 21 are formed. In this case, the metal layer formed by electroless plating is used as the anode metal layer 20 and the cathode metal layer 21. Remove so that it remains.

FIG. 3 (g) shows a state in which the anode metal layer 20 and the cathode metal layer 21 are covered with a solder metal layer.
22 is a solder metal layer on the anode side, and 23 is a solder metal layer on the cathode side. These solder metal layers 22 and 23 are formed by solder coating with molten solder or electrolytic solder plating.

In the above embodiment of the present invention,
The capacitor element 11a provided with the cathode conductor layer 16 separately from the cathode layer 15 has been described. However, when the capacitor element 11a is covered with the exterior resin 18, the cathode layer 15 is directly exposed from the end surface of the exterior resin 18. May be configured so that the cathode part is exposed from the end surface of the exterior resin 18.

[0017]

As described above, according to the present invention, since the anode metal layer is formed on the anode lead-out surface of the exterior resin on the anode lead-out wire exposed from the exterior resin, the conventional external terminal is not used. It is possible to save a space for taking out to the outside and a space for bending an external terminal, which makes it possible to increase the volumetric efficiency of the capacitor by a factor of 2 to 3 and to reduce the size and capacity of the capacitor. Further, if the anode metal layer is composed of a metal layer including an electroless plating layer, the anode metal layer that will be the anode terminal and the anode lead wire will be connected at the same time, thereby significantly reducing the production cost. Since the anode metal layer is provided so as to cover all surfaces of the anode lead wire exposed from the exterior resin,
Even when subjected to a solder heat resistance test, a humidity resistance test at 60 ° C. and 90% RH, or mechanical stress during automatic mounting, physical deterioration is unlikely to occur at the interface between the anode lead wire and the anode metal layer, and good electrical The characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a chip-shaped tantalum solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a state in which a cathode conductor layer is formed on a capacitor element of the same capacitor.

3 (a) to (g) are external perspective views showing a manufacturing process of a chip-shaped tantalum solid electrolytic capacitor in one embodiment of the present invention.

FIG. 4 is a sectional view of a conventional chip-shaped tantalum solid electrolytic capacitor.

[Explanation of symbols]

 11 Anode body 11a Capacitor element 12 Anode lead wire 12a Anode lead surface 15 Cathode layer 16a Cathode lead surface 18 Exterior resin 20 Anode metal layer 21 Cathode metal layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Ida 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] Claim: What is claimed is: 1. A capacitor element comprising a dielectric oxide film, an electrolyte layer and a cathode layer provided on an anode body made of a valve metal in which an anode lead wire is embedded so that one end of the anode lead wire is exposed. This capacitor element is coated so as to be exposed in a direction in which the anode lead wire and the cathode portion are opposed to each other, and the anode lead-out surface of the outer cover resin covers all the surfaces of the anode lead wire exposed from the lead resin. And a cathode metal layer provided on the cathode portion of the exterior resin so as to be electrically connected to the cathode layer. 2. The chip solid electrolytic capacitor according to claim 1, wherein the anode metal layer is a metal layer including an electroless plating layer. 3. The thickness of the electroless plating layer is 0.5 to 5.0 μm.
The chip-shaped solid electrolytic capacitor according to claim 2, wherein the solid electrolytic capacitor is m. 4. A capacitor element is formed by sequentially laminating a dielectric oxide film, an electrolyte layer and a cathode layer on an anode body made of a valve metal in which an anode lead wire is embedded so that one end of the anode lead wire is exposed. Further, the capacitor element is covered with an exterior resin so that the anode lead wire and the cathode portion are exposed in a direction opposite to each other, and then all the anode lead wires exposed from the exterior resin on the anode lead surface of the exterior resin. An anode metal layer is formed so as to cover the surface of the chip, and then a cathode metal layer is formed on the cathode portion of the exterior resin so as to be electrically connected to the cathode layer. Manufacturing method.