JPH0590099A - Chip type solid electrolytic capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a chip type solid electrolytic capacitor, which can prevent electric properties from deteriorating by preventing moisture or ionic substances from penetrating into the capacitor element at high temperature and high humidity in use or in the plating process in manufacture. CONSTITUTION:A capacitor element 11a, which is equipped with an anode lead wire 12 and is constituted by stacking a dielectric oxide film, an electrolytic layer, and a cathode layer 15 in order on the surface of the anode body 11 consisting of a valve acting metal 11, is soaked in volatile resin 17 and is coated with volatile resin 17.

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 method for manufacturing a chip-shaped tantalum solid electrolytic capacitor will be described below with reference to the flow chart of FIG.

First, an anode lead wire 2 drawn from a capacitor element 1 made of a porous anode body made of a valve metal is attached to a metal ribbon 3. From the next step, metal ribbons are handled in units of 3 units, and a dielectric oxide film, an electrolyte layer, a cathode layer 4 composed of a carbon layer and a silver coating layer are sequentially laminated on the surface of a porous anode body made of a valve metal. The capacitor element 1 is formed. Then, a cathode conductor layer 5 is formed on a portion of the cathode layer 4 opposite to the anode lead wire 2. After that, the capacitor element 1 and the cathode conductor layer 5 are covered with an exterior resin 6 so that the anode lead wire 2 is drawn out to one side, and then the cathode side of the exterior resin 6 is exposed to the cathode conductor layer 5. Cut or grind. Next, the anode metal layer 7 and the cathode metal layer 8 are formed on the anode lead-out surface 2a and the cathode lead-out surface 5a. After that, the anode metal layer 7 and the cathode metal layer 8 are coated with the solder metal layers 9 and 10, and the anode lead wire 2 is cut so that the completed chip-shaped tantalum solid electrolytic capacitor has a specified size. The individual pieces were separated from the ribbon 3 and the characteristics of the capacitor were inspected.

[0005]

However, in such a chip-shaped tantalum solid electrolytic capacitor, leakage current, tan δ, etc. are apt to deteriorate due to invasion of moisture from the outside, and in particular, the purpose of miniaturization and high capacity of the solid electrolytic capacitor is to be improved. so,
When the metal layer 7 and the cathode metal layer 8 which are the lead-out portions of the terminals are formed by the plating method, the solid electrolytic capacitor is immersed in the plating solution, so that moisture and ionic substances enter the inside of the capacitor element 1. However, there is a problem that the electrical characteristics are easily deteriorated.

The present invention solves the above-mentioned problems of the prior art by preventing moisture and ionic substances from entering the capacitor element during high temperature and high humidity during use or during the plating process during manufacture. It is an object of the present invention to provide a chip-shaped solid electrolytic capacitor capable of preventing the deterioration of the static characteristics.

[0007]

In order to achieve the above object, a chip solid electrolytic capacitor of the present invention is provided with an anode lead wire and has a dielectric oxide film and an electrolyte on the surface of an anode body made of a valve metal. A capacitor element formed by sequentially stacking layers and a cathode layer, an exterior resin that covers the capacitor element so that the anode lead wire and the cathode portion are exposed in a direction opposite to each other, an anode lead surface of the exterior resin, and It is provided with an anode metal layer and a cathode metal layer formed in the cathode part, and the capacitor element is immersed in a water-repellent resin to coat the capacitor element with the water-repellent resin.

[0008]

According to the above construction, the capacitor element is immersed in the water-repellent resin to coat the capacitor element with the water-repellent resin. The water-repellent resin constitutes not only the outermost surface of the capacitor element but also the anode body. Since the protective film is formed by penetrating into the valve metal, the moisture and ionic substances that enter from outside do not come into contact with the valve metal, which prevents the electrical characteristics of the solid electrolytic capacitor from increasing. It is possible to prevent deterioration. In particular, when the method of forming the anode metal layer and the cathode metal layer by the plating method is used, it is immersed in a strong acid / strong alkaline solution at high temperature, but in this case also, the capacitor element is covered with a water-repellent resin. Therefore, the deterioration of the electrical characteristics does not occur.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a chip-shaped tantalum solid electrolytic capacitor according to an embodiment of the present invention, and FIG. 2 is a flow chart of a manufacturing method of the chip-shaped tantalum solid electrolytic capacitor. 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. The anode lead wire 12 is made of tantalum wire and is led out from the anode body 11. Then, a series of processing steps on the surface of the anode body 11 is performed in a state where the anode lead wire 12 is connected to the metal ribbon 13. 14 is a Teflon plate attached to the anode lead-out wire 12, and this Teflon plate 14 is the anode body 1
It is an insulating plate that prevents manganese dioxide from creeping up and adhering to the anode lead wire 12 when the electrolyte layer is formed on the anode 1. 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. Further, in the portion of the capacitor element 11a located on the side opposite to the anode lead wire 12 of the cathode layer 15, the cathode conductor layer 16 is sequentially laminated by being dipped in a coating material containing silver powder as a main component. After that, the capacitor element 11a and the cathode conductor layer 16 in this state are immersed in a silicone-based or fluorine-based water-repellent resin 17 to form the capacitor element 11a.
The cathode conductor layer 16 is entirely covered with the water-repellent resin 17. In this case, the water-repellent resin 17 having high penetrability permeates into the inside of the porous anode body 11 by immersion to form a protective film.

Next, the capacitor element 11 is packaged with an epoxy resin by a transfer molding method so that the anode lead wire 12 is drawn out to one side, and then the package resin 18 is cut or ground so that the cathode conductor layer 16 is exposed. .. Then, after pretreatment of alkali degreasing, chemical etching and catalyst application, electroless Ni plating is applied to the surfaces of the anode lead wire 12, the anode lead surface 12a, the cathode lead surface 16a and the molded body of the exterior resin 18 with Ni. And a cathode metal layer 20 made of Ni are formed. In this case, the thickness of the anode metal layer 19 and the cathode metal layer 20 in the range of 0.5 to 5.0 μm is excellent in the bonding strength with the base. Then, solder metal layers 21 and 22 are provided on the both electrodes through the anode metal layer 19 and the cathode metal layer 20. The anode lead wire 12 is cut into individual pieces from the metal ribbon 13 so that the chip-shaped tantalum solid electrolytic capacitor manufactured as described above has an external product size, and it is completed after being inspected.

In one embodiment of the present invention described above, a cathode layer composed of a dielectric oxide film, an electrolyte layer, a carbon layer and a silver coating layer is formed on the surface of a porous anode body 11 obtained by molding and sintering tantalum metal powder. 15 are sequentially laminated and the capacitor element 11a and the cathode conductor layer 16 are immersed in a silicone-based or fluorine-based water-repellent resin 17 to cover the capacitor element 11a and the cathode conductor layer 16 with the water-repellent resin 17. In this case, the water-repellent resin 17 having high permeability is not only formed on the outermost surface of the capacitor element 11a but also on the porous anode body 11 due to the immersion.
Since a protective film is formed by penetrating to the inside of the N, the anode metal layer 19 and N made of Ni are formed by electroless Ni plating.
In the plating process for forming the cathode metal layer 20 made of i, the capacitor element 11a is exposed to severe conditions,
That is, even if the capacitor element 11a is immersed in a strong acid / strong alkaline solution at a high temperature, the presence of the protective film can prevent the deterioration of the electrical characteristics, and also in a high temperature / high humidity condition under a use environment, By the presence of the protective film,
Since water and ionic substances that have entered from the outside do not come into contact with the porous anode body 11 made of a valve metal,
It is possible to prevent deterioration of the electrical characteristics of the chip solid electrolytic capacitor.

FIG. 3 shows the electrical characteristics (ta) of the chip-shaped tantalum solid electrolytic capacitor in one embodiment of the present invention.
4 is a graph showing the results of comparing the electrical characteristics (tan δ) of a conventional chip-shaped tantalum solid electrolytic capacitor, and as is apparent from FIG. 3, the chip-shaped tantalum solid of one embodiment of the present invention is shown. The electrolytic capacitor has less deterioration in electrical characteristics than the conventional chip-shaped tantalum solid electrolytic capacitor.

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.

[0015]

As described above, in the chip solid electrolytic capacitor of the present invention, the capacitor element is immersed in the water-repellent resin and the capacitor element is covered with the water-repellent resin. Not only the outermost surface, but also the valve action metal that composes the anode body penetrates to form a protective film, so that moisture and ionic substances that enter from the outside do not come into contact with the valve action metal. As a result, it is possible to prevent the deterioration of the electrical characteristics of the solid electrolytic capacitor. In particular, when the method of forming the anode metal layer and the cathode metal layer by the plating method is used, it is immersed in a strong acid / strong alkaline solution at high temperature, but in this case as well, the capacitor element is coated with a water-repellent resin. Therefore, the electrical characteristics are not deteriorated.

[Brief description of drawings]

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

FIG. 2 is a flow chart of a method for manufacturing the same chip-shaped tantalum solid electrolytic capacitor.

FIG. 3 is a graph showing a comparison of electrical characteristics between a chip-shaped tantalum solid electrolytic capacitor according to an embodiment of the present invention and a conventional chip-shaped tantalum solid electrolytic capacitor.

FIG. 4 is a flow chart of a method for manufacturing a conventional chip-shaped tantalum solid electrolytic capacitor.

[Description of Reference Signs] 11 Anode body 11a Capacitor element 12 Anode lead wire 15 Cathode layer 17 Water repellent resin 18 Exterior resin 19 Anode metal layer 20 Cathode metal layer

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

Claims (2)

[Claims] Claim: What is claimed is: 1. A capacitor element comprising an anode lead wire and a dielectric oxide film, an electrolyte layer, and a cathode layer, which are sequentially laminated on the surface of an anode body made of a valve metal, and a capacitor element covered with the capacitor element. A water-repellent resin, an exterior resin that covers the capacitor element so that the anode lead wire and the cathode portion are exposed in the opposite direction, and an anode metal layer formed on the anode lead surface and the cathode portion of the exterior resin. And a chip-shaped solid electrolytic capacitor having a cathode metal layer. 2. A capacitor element is formed by sequentially laminating a dielectric oxide film, an electrolyte layer, and a cathode layer on the surface of an anode body having an anode lead wire and made of a valve metal, and forming the capacitor element The capacitor element is covered with a water-repellent resin by immersing in a water-based resin, and then 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. A method for manufacturing a chip-shaped solid electrolytic capacitor, which comprises forming an anode metal layer and a cathode metal layer on an anode lead-out surface and a cathode portion of a resin.