JPH0590088A - Chip type solid electrolytic capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a chip-type solid electrolytic capacitor and manufacture thereof, wherein short circuit and defective characteristic can be eliminated by preventing a cathode layer from being directly exposed to the surface of the armor resin. CONSTITUTION:A cathode layer 15 is prevented from being exposed directly to the surface of armor resin 19 when armor resin 19 is molded by equipping a capacitor element 11a, which is constituted by stacking a dielectric oxide film, an electrolytic layer, and a cathode layer 5 in order on the anode body 11 consisting of the valve acting metal burying an anode lead wire 12 so that one end of the anode lead wire 12 is exposed, and providing an insulating resin layer 18 on the surface of the cathode layer 15 in, at least, the capacitor element 11a.

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. 5, 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. A cathode conductor layer 5 is formed on a portion of the capacitor element 1a opposite to the anode lead wire 2 in the cathode layer 4, and then the capacitor element 1a and the cathode conductor layer 5 are connected to the anode lead wire 2 on one side. The exterior resin 6 is covered with the exterior resin 6 to form a molded body of the exterior resin 6, and the anode lead-out surface 7 and the cathode lead-out surface 8 of the exterior resin 6 are formed.
The chip-shaped solid electrolytic capacitor was formed by forming the anode metal layer 9 and the cathode metal layer 10 on.

[0004]

However, in such a conventional chip-shaped tantalum solid electrolytic capacitor as described above, when the anode lead wire is bent when the molded body of the exterior resin 6 is formed by molding, the external The cathode layer 4 and the cathode conductor layer 5 are formed on the surface of the exterior resin 6 which is different from the portions where the anode metal layer 9 and the cathode metal layer 10 which become the electrodes are formed.
When the capacitor layer is exposed on the printed circuit board and solder is attached to the cathode layer 4 and the cathode conductor layer 5 exposed on the surface of the exterior resin 6, the short circuit between the anode and the cathode occurs. There is a problem that defects are likely to occur and cracks occur in the dielectric oxide film formed at the connecting portion between the surface of the anode lead wire 2 and the anode body 1 and the leakage current characteristics are poor.

The present invention solves the above-mentioned conventional problems, and prevents the cathode layer from being directly exposed on the surface of the exterior resin to eliminate short-circuit defects and characteristic defects, and a chip-like solid electrolytic capacitor. It is an object of the present invention to provide a method for manufacturing a chip-shaped solid electrolytic capacitor which can be manufactured inexpensively and easily in mass production.

[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 insulating layer, an insulating resin layer formed on at least the surface of the cathode layer in the capacitor element, the capacitor element and the insulating resin layer. An exterior resin covering the anode lead wire and the cathode portion so as to be exposed in opposite directions, and an anode metal layer and a cathode metal layer formed on the anode lead surface and the cathode portion of the exterior resin. is there.

[0007]

According to the above construction, since the insulating resin layer is formed on at least the surface of the cathode layer in the capacitor element, the anode lead wire is bent when the molded body of the exterior resin is formed by molding. Even if it does, the cathode layer will not be directly exposed on the surface of the exterior resin different from the portion forming the anode metal layer and the cathode metal layer which will be the external electrodes, and as a result, when the capacitor is mounted on the printed circuit board, It is no longer the case that solder adheres to the exposed cathode layer etc. as in the past and causes a short circuit between the anode and the cathode,
When forming a molded body of exterior resin by molding,
Since the insulating resin layer touches the mold for molding, the eccentricity of the anode lead wire can be reduced, which causes cracks in the dielectric oxide film formed at the connection between the anode lead wire and the surface of the anode body. Since it is possible to reduce the occurrence of the leakage current, the leakage current characteristic can be improved.

[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, FIG. 2 shows a state where a cathode conductor layer is formed on a capacitor element, and FIG. 3 shows a cathode layer and a cathode conductor. It shows a state in which an insulating resin layer is formed on the layer. Figure 1, Figure 2,
In FIG. 3, 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, and further on this surface. An electrolyte layer such as manganese dioxide is formed. The anode lead wire 12 is made of tantalum wire and is led out from the anode body 11. Then, the series of processing steps on the surface of the anode body 11 is performed by the metal ribbon 1.
It is performed in a state where the anode lead wire 12 is connected to 3. 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. Reference numeral 16 denotes a cathode conductor layer. The cathode conductor layer 16 is a cathode layer 15 of the capacitor element 11a, and an opposing surface 17 located on the opposite side of the anode lead wire 12 and an adjacent surface adjacent to the opposing surface 17. Is formed on a part of the cathode layer 15. In this case, the cathode conductor layer 1
6 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 insulating resin layer. The insulating resin layer 18 is formed by immersing the capacitor element 11a on which the cathode conductor layer 16 is formed in a liquid of an insulating resin and then curing the same to form the cathode layer 15 and the cathode conductor layer. It is formed on the surface of 16. 19 is an exterior resin, and this exterior resin 19
Sets the capacitor element 11a in the mold so that the anode lead wire 12 is drawn out to one side, and includes the cathode conductor layer 16 and the insulating resin 18 in the capacitor element 11a.
It is formed by transfer molding or injection molding using an epoxy resin so that the whole is covered with resin. At this time, even if the anode lead wire 12 is largely bent and eccentric due to the injection pressure of the exterior resin 19, or the anode lead wire 12 is already eccentric, the insulating resin layer 18 is molded. Since the metal layers of the cathode layer 15 and the cathode conductor layer 16 are not directly exposed to the surface of the exterior resin 19, the eccentricity of the anode lead wire 12 can be reduced. Further, when the color of the insulating resin layer 18 is set to be the same as the color of the exterior resin 19, the exterior resin 19 different from the portions where the insulating resin layer 18 forms the anode metal layer 20 and the cathode metal layer 21 which serve as external electrodes. Even if it is exposed on the surface of, it cannot be distinguished from the exterior resin 19, so that it is possible to easily prevent the appearance defect. Further, when the insulating resin layer 18 is made of a resin having a low elasticity, it is possible to reduce mechanical stress on the capacitor element 11a due to thermal expansion of the exterior resin 19 when a resin exterior, heat resistance test, or thermal shock test is performed. This makes it possible to obtain a chip solid electrolytic capacitor having excellent leakage current characteristics.

FIGS. 4 (a), (b), (c), (d), and (e) show the manufacturing process of the chip-shaped tantalum solid electrolytic capacitor in one embodiment of the present invention. Reference numeral 12a denotes an anode lead-out surface of the exterior resin 19.
Since the cathode conductor layer 16 formed on the facing surface 17 of the exterior resin 19 opposite to the anode lead wire 12 is longer than the external dimensions of the product, the exterior resin 19
The molded product of is longer than the external dimensions of the product.

FIG. 4B shows a state in which the molded body of the exterior resin 19 in FIG. 4A is cut or ground to the external dimensions of the product. In FIG. 4B, 16a is a cathode lead-out surface, and this cathode lead-out surface 16a is formed by cutting the exterior resin 19, the cathode conductor layer 16, and the insulating resin layer 18.
As shown in FIG. 1, the cathode lead-out surface 16
The insulating resin layer 18 is removed at a and the cathode conductor layer 16 is exposed.

FIG. 4C shows a state in which the anode lead wire 12 is separated from the metal ribbon 13.

FIG. 4 (d) shows a state in which the anode metal layer 20 and the cathode metal layer 21 are formed. This metal layer is shown in FIG.
As shown in FIG. 4, the anode lead wire 12, the anode lead-out surface 12a, and a part of the molded body of the exterior resin 19 and the anode metal layer 20 formed on the surface of the molded body of the cathode lead-out surface 16a and the exterior resin 19. And a cathode metal layer 21 formed on the surface of the cathode metal layer 21 and the cathode metal layer 21 and the cathode metal layer 21.
Is electroless plating, wet forming method of electrolytic plating and vapor deposition,
It is formed by a dry forming method of ion sputtering, and in this case, a conductive resin layer may be included.

FIG. 4 (e) 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 19, the cathode layer 15 is directly exposed from the end surface of the exterior resin 19. It is sufficient that the cathode portion is exposed from the end surface of the exterior resin 19.

[0015]

As described above, according to the present invention, since the insulating resin layer is formed on at least the surface of the cathode layer in the capacitor element, when the molded body of the exterior resin is formed by molding, the anode lead Even if the wire bends, the cathode layer will not be directly exposed on the surface of the external resin that is different from the part that forms the anode metal layer and the cathode metal layer that will be the external electrodes. When mounted on, the solder will no longer adhere to the exposed cathode layer, etc. to cause a short circuit between the anode and the cathode, and when forming a molded body of exterior resin by molding, the insulating resin layer Touches the mold for molding, so it is possible to reduce the eccentricity of the anode lead wire.
Since it is possible to reduce the occurrence of cracks in the dielectric oxide film formed at the connection between the anode lead wire and the surface of the anode body, it is possible to improve the leakage current characteristics.

[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.

FIG. 3 is a sectional view showing a state in which an insulating resin layer is formed on a cathode layer and a cathode conductor layer in the same capacitor.

4A to 4E are external perspective views showing a manufacturing process of a chip-shaped tantalum solid electrolytic capacitor in one embodiment of the present invention.

FIG. 5 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 Insulating resin layer 19 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. At least an insulating resin layer formed on the surface of the cathode layer in the capacitor element, and an exterior resin that covers the capacitor element and the insulating resin layer so that the anode lead wire and the cathode portion are exposed so as to be exposed in opposite directions. A chip-shaped solid electrolytic capacitor provided with an anode metal layer and a cathode metal layer formed on the anode lead-out surface of the exterior resin and the cathode portion. 2. The chip solid electrolytic capacitor according to claim 1, wherein the insulating resin layer has the same color as the exterior resin. 3. The chip solid electrolytic capacitor according to claim 1, wherein the insulating resin layer is a resin having a low elasticity. 4. A capacitor element is constructed 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 the anode lead wire is embedded so that one end of the anode lead wire is exposed. Further, at least the cathode layer in the capacitor element is dipped in an insulating resin and cured to form an insulating resin layer on the surface of the cathode layer, and then the capacitor element and the insulating resin layer are formed on the anode. A chip characterized in that a lead wire and a cathode part are covered with an exterior resin so as to be exposed in opposite directions, and then an anode metal layer and a cathode metal layer are formed on the anode lead surface and the cathode part of the exterior resin. Of manufacturing a solid electrolytic capacitor.