JPH06252012A - Chip-shaped solid electrolytic capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a chip-shaped solid electrolytic capacitor and its manufacture, which can sharply simplify the process of forming an anode metallic layer and a cathode metallic layer, and can improve the tan delta property, and besides can improve the leak current property in moisture resistance test. CONSTITUTION:A capacitor element is covered with topcoat resin 19 in the direction where an anode lead wire 12 and a cathode part face each other, and a water-repellant coating layer 21 is formed on the surface of the nonelectrode terminal at the center of this topcoat resin 18. Furthermore, metallic particles to serve as catalysts are given to the surface of the topcoat resin 18 excluding this water-repellant coating layer 21 and the anode lead wire 12 and a cathode part, and an anode metallic layer 19 and a cathode metallic layer 20 are formed at this section which are given metallic fine particles by plating.

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 A conventional solid electrolytic capacitor chip and its manufacturing method will be described with reference to FIG. First, a dielectric oxide film formed by anodic oxidation is formed on the surface of a porous anode body 2 which is made of tantalum metal which is a valve metal and has an anode lead wire 1, and an electrolyte such as manganese dioxide is formed on this surface. And a carbon layer and a cathode layer 3 are sequentially laminated to form a capacitor element 4, and the capacitor element 4 is formed by projecting the tip 1a of the anode lead wire 1 and the exposed portion 3a of the cathode layer 3. The outer surface of the anode lead wire 1 and the outer cover resin 5 is roughened, and a catalyst is applied to perform Ni plating on the entire surface.
Anode lead wire 1 of exterior resin 5 including protruding tip 1a of
Of the extraction surface and the peripheral surface adjacent to that surface, the cathode side end of the exterior resin 5 including the exposed portion 3a of the cathode layer 3 and the peripheral surface adjacent to this surface are covered with a resist, and then exposed. The Ni plating layer is acid-dissolved and removed.

Finally, by removing the resist by alkali dissolution, the lead-out surface of the anode lead-out wire 1 of the exterior resin 5 including the protruding tip portion 1a of the anode lead-out wire 1 and the peripheral surface adjacent to that surface, The anode metal layer 6 and the cathode metal layer 7 are formed by exposing the cathode side end portion of the exterior resin 5 including the exposed portion 3a of the cathode layer 3 and the peripheral surface adjacent to this surface. In addition, 8 is a solder metal layer on the anode side, and 9 is a solder metal layer on the cathode side.

[0004]

However, in such a chip solid electrolytic capacitor and its manufacturing method, when the anode metal layer 6 and the cathode metal layer 7 are formed, the entire surface of the exterior resin 5 is plated with Ni. After that, the portions where the anode metal layer 6 and the cathode metal layer 7 are formed are covered with a resist, the Ni plating layer of the non-electrode terminal portion in the exterior resin 5 is subsequently acid-dissolved, and the resist is removed by alkali dissolution. As a result, the anode metal layer 6 and the cathode metal layer 7 are formed, so that the manufacturing method thereof is complicated, and a chemical agent is used to remove the Ni plating layer and the resist. The characteristics are adversely affected, and since the exterior resin 5 easily absorbs moisture, leakage current characteristics are likely to deteriorate in the moisture resistance test. It had.

The present invention solves the above-mentioned conventional problems. The steps of forming the anode metal layer and the cathode metal layer can be greatly simplified, and the tan δ characteristic can be improved, and the humidity resistance test can be performed. An object of the present invention is to provide a chip-shaped solid electrolytic capacitor capable of improving leakage current characteristics and a method for manufacturing the same.

[0006]

In order to achieve the above object, a chip-shaped solid electrolytic capacitor of the present invention and a method for manufacturing the same are provided with a valve metal in which an anode lead wire is embedded so that one end of the anode lead wire is exposed. A capacitor element is formed by providing a dielectric oxide film, an electrolyte layer and a cathode layer on an anode body made of, and the capacitor element is covered with an exterior resin so that the anode lead wire and the cathode portion are exposed in opposite directions. Coated,
And a water-repellent coating layer is formed on the surface of the non-electrode terminal portion in the center of the exterior resin, and metal fine particles serving as a catalyst for plating are formed on the surface of the exterior resin other than the water-repellent coating layer, the anode lead wire, and the cathode portion. In addition to the application, the anode metal layer and the cathode metal layer are formed by plating on the portions to which the metal fine particles are applied.

[0007]

According to the above-described chip-shaped solid electrolytic capacitor of the present invention and the method for manufacturing the same, the capacitor element is covered with the exterior resin so that the anode lead wire and the cathode portion are exposed in the opposite directions, and the exterior When the anode metal layer and the cathode metal layer are formed on the resin, the water-repellent coating layer is formed on the surface of the non-electrode terminal portion in the center of the exterior resin. The solution containing the fine particles will be repelled at the portion where the water repellent coating layer is formed, and as a result, the metal fine particles that serve as a plating catalyst are not applied to the portion where the water repellent coating layer is formed, and other than that. Since it will be applied to the surface of the exterior resin, the anode lead wire, and the cathode part, the anode metal layer and the cathode metal layer formed by plating should be applied to the electrode terminal part other than the part where the water-repellent coating layer is formed. It can be rate formed.

Since this eliminates the conventional step of removing the plating layer and the resist, the step of forming the anode metal layer and the cathode metal layer can be greatly simplified, and the removal step of the plating layer and the resist can be performed. Since the existing chemicals can be omitted, the tan δ characteristic can be improved, and the influence of moisture can be mitigated by the water-repellent paint layer formed on the surface of the non-electrode terminal portion in the center of the exterior resin, so the moisture resistance test It is also possible to improve the leakage current characteristic in the above.

[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 shows a sectional view of a chip solid electrolytic capacitor in one embodiment of the present invention, and FIG. 2 shows a state in which the cathode conductor layer of the chip solid electrolytic capacitor shown in FIG. 1 is formed thick. It is a thing.

1 and 2, reference numeral 11 denotes 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 the anode body 11 by anodic oxidation. Further, 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. 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. 1
Reference numeral 4 denotes a Teflon plate attached to the anode lead-out wire 12. This Teflon plate 14 is an insulating member for preventing manganese nitrate from crawling up and adhering to manganese dioxide to the anode lead-out wire 12 when the electrolyte layer is formed on the anode body 11. It is a plate.

A cathode layer 1 comprising a carbon layer and a silver coating layer is formed on the electrolyte layer of the anode body 11 by a dipping method.
5 are sequentially laminated to form the capacitor element 11a. 16 is a cathode conductor layer, and this cathode conductor layer 16
Of the cathode layer 15 in the capacitor element 11a,
It is formed on the facing surface 17 located on the side opposite to the anode lead-out line 12 and a part of the cathode layer 15 on the adjacent surface adjacent to the facing surface 17. In this case, the cathode conductor layer 16 is made of a conductive material composed of a thermosetting resin containing silver powder as a main component, and the capacitor element 11a is dipped in a viscous liquid whose viscosity is adjusted appropriately and dried in a constant temperature bath. It is formed by curing.

The conductive material may be a metal mixed powder of any one of Pd, Ni and Cu or a mixture of two or three of them, and the thermosetting resin is heated to 150 to 180 ° C. It hardens. 2 such dipping and drying
It is possible to repeat the process three to three times to deposit the material in a thick and convex shape as shown in FIG.

Further, the cathode conductor layer 16 is preferably made of a material having low water absorption and hygroscopicity and excellent moisture resistance. On the other hand, it may be a metal material such as a metal plate such as nickel. That is, this conductive material must be one that does not allow the processing liquid used later for forming the metal layer to enter the inside of the capacitor element 11a. The binder of the cathode layer 15 is excellent in polyether amide type, and the cathode conductor layer 16 including the cathode layer 15 is impregnated with silicon oil or the like to prevent the treatment liquid from entering the inside of the capacitor element 11a. It can be further suppressed.

This has the effect of reducing the deterioration of characteristics such as LC, tan δ and ΔC. Reference numeral 18 in FIG. 1 is an exterior resin, and the exterior resin 18 is the anode lead wire 1
Set the capacitor element 11a in the mold so that 2 is pulled out to one side, and by the transfer molding method,
Capacitor element 11a including the cathode conductor layer 16 of FIG.
Is coated with epoxy resin.

3 (a), (b), (c), (d) and (e) show a manufacturing process of a chip solid electrolytic capacitor in one embodiment of the present invention. In FIG.
Is the anode lead-out surface of the exterior resin 18, and this anode lead-out surface 12a is the anode lead-out wire 12 in the molded body of the exterior resin 18.
Is formed in the vicinity of the concave shape, and due to this concave shape, the anode lead wire 12 bent upward does not protrude from the outer dimension of the molded body of the exterior resin 18, and a large exposed area can be taken. it can. On the other hand, since the cathode conductor layer 16 formed on the facing surface 17 located on the opposite side of the anode lead wire 12 is longer than the external dimensions of the product,
The molded body of the exterior resin 18 is long.

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 standard. 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 at
The surface of the molded body of the cathode lead-out surface 16a and the exterior resin 18 is polished by either or both of sand blasting and chemical etching to roughen the surface, thereby preventing catching due to fine unevenness and surface activation. Is going. The exterior resin 18 is composed of only an epoxy resin or an epoxy resin containing fibrous silicon oxide having a particle size of 1 to 200 μm, a diameter of 2 to 20 μm, and a length of 10 to 1000 μm.

A polyimide resin may be contained in addition to the above-mentioned silicon oxide. Further, the sandblast is made of glass, alumina, or titanium oxide, and the particle size at that time is 100 μm or less so as to enter the concave groove of FIG. Further, in the chemical etching, hydrofluoric acid, permanganate, and sodium hydroxide are used for the purpose of roughening the surface of the epoxy resin and the filler silicon oxide. At this time, the connection strength between the surface of the exterior resin 18 and the anode metal layer 19 and the cathode metal layer 20 can be further increased by roughening the surface by a combination of sandblasting and chemical etching.

FIG. 3 (c) shows a state in which the anode lead-out wire 12 is bent upward within the concave shape of the anode lead-out surface 12a and the anode lead-out wire 12 is separated from the metal ribbon 13. Since the wire 12 can have a large surface area of the anode lead-out surface 12a and the anode lead-out wire 12 can be housed in the recess of the anode lead-out surface 12a, the external shape can be integrated into a rectangular parallelepiped. In this case, the anode lead-out surface 12 is attached to the anode lead-out wire 12.
If a weak point by rolling or cutting is provided inside the concave shape of 2a, the bending position is determined,
Moreover, since the bent shape is stable, the anode lead wire 12 can be housed inside the concave shape of the anode lead surface 12a without applying stress.

FIG. 3D shows the state of formation of the metal layer. The metal layer includes the anode lead wire 12 and the anode lead surface 12.
a and the anode metal layer 19 formed on the surface of part of the molded body of the exterior resin 18, and the cathode lead-out surface 16a and the cathode metal layer 20 formed on the surface of part of the molded body of the exterior resin 18.
The anode metal layer 19 and the cathode metal layer 20 are subjected to alkali degreasing and chemical etching, and then printed with a water-repellent paint on the surface of the non-electrode terminal portion at the center of the exterior resin 18 to obtain a water-repellent paint. The layer 21 is formed, and a part of the molded body of the exterior resin 18 other than the water-repellent coating layer 21, the anode lead wire 12, the anode lead surface 12a, and the cathode lead surface 1 are formed.
Metal fine particles serving as a plating catalyst are provided on each surface of 6a, and further electroless Ni plating is performed to form metal fine particle provided portions.

FIG. 3 (e) shows a state in which both electrodes are covered with a solder metal layer, and 22 is a solder metal layer on the anode side.
Reference numeral 23 is a solder metal layer on the cathode side. These solder metal layers 22 and 23 are formed by solder coating in a molten solder bath.
Covers the surface of the anode metal layer 19 as shown in FIG. 1, while the cathode side solder metal layer 23 covers the surface of the cathode metal layer 20 as shown in FIG.

The product thus produced is aged, heat-treated, etc., and then inspected to obtain a finished product.

FIG. 4 shows the leakage current characteristics in the moisture resistance test of the chip solid electrolytic capacitor in one embodiment of the present invention and the conventional chip solid electrolytic capacitor.

As is apparent from FIG. 4, the chip solid electrolytic capacitor of the present invention has the water repellent coating layer 21 formed on the surface of the non-electrode terminal portion in the center of the exterior resin 18, so that the chip solid electrolytic capacitor of the conventional chip solid electrolytic capacitor is formed. The leakage current characteristic in the humidity resistance test can be improved as compared with the electrolytic capacitor.

[0026]

As described above, according to the present invention, the capacitor element is covered with the exterior resin so as to be exposed in the direction in which the anode lead wire and the cathode portion are opposed to each other, and the exterior resin is coated with the anode metal layer. When the cathode metal layer is formed, since the water-repellent coating layer is formed on the surface of the non-electrode terminal portion in the center of the exterior resin, the solution containing the metal fine particles to be the catalyst for the plating applied thereafter is It will be repelled at the portion where the water-repellent coating layer is formed, and as a result, the fine metal particles that serve as a catalyst for plating are not applied to the portion where the water-repellent coating layer is formed, and the other surface of the exterior resin and Since it is provided to the anode lead wire and the cathode portion, the anode metal layer and the cathode metal layer formed by plating can be efficiently formed on the electrode terminal portion other than the portion where the water-repellent coating layer is formed. .

Since this eliminates the conventional step of removing the plating layer and the resist, the step of forming the anode metal layer and the cathode metal layer can be greatly simplified, and the removal step of the plating layer and the resist can be performed. Since the existing chemicals can be omitted, the tan δ characteristic can be improved, and the influence of moisture can be mitigated by the water-repellent paint layer formed on the surface of the non-electrode terminal portion in the center of the exterior resin, so the moisture resistance test It is also possible to improve the leakage current characteristic in the above.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a state in which the cathode conductor layer of the chip-shaped solid electrolytic capacitor is thickly formed.

3A to 3E are perspective views showing a manufacturing process of the same chip solid electrolytic capacitor.

FIG. 4 is a characteristic diagram showing leakage current characteristics in a moisture resistance test of a chip solid electrolytic capacitor according to an embodiment of the present invention and a conventional chip solid electrolytic capacitor.

FIG. 5 is a sectional view showing a conventional chip solid electrolytic capacitor.

[Explanation of symbols]

 11 Anode body 11a Capacitor element 12 Anode lead wire 15 Cathode layer 16 Cathode conductor layer 18 Exterior resin 19 Anode metal layer 20 Cathode metal layer 21 Water repellent paint layer

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

Claims (2)

[Claims] 1. A capacitor element having a dielectric oxide film, an electrolyte layer and a cathode layer provided on an anode body made of valve metal embedded so that one end of the anode lead wire is exposed, and the anode lead wire. The exterior resin coated so that the cathode and the cathode are exposed in opposite directions, the water-repellent coating layer formed on the surface of the non-electrode terminal portion in the center of the exterior resin, and the surface of the exterior resin other than this water-repellent coating layer. And a chip-shaped solid electrolytic capacitor provided with the anode lead wire, an anode metal layer formed on the cathode portion, and a cathode metal layer. 2. A capacitor element is constructed by providing 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. This capacitor element is covered with an exterior resin so that the anode lead-out wire and the cathode portion are exposed in opposite directions, and a water-repellent coating layer is formed on the surface of the non-electrode terminal portion in the center of the exterior resin. Metal fine particles serving as a plating catalyst are applied to the surface of the exterior resin other than the water-repellent coating layer, the anode lead wire, and the cathode layer, and the anode metal layer and the cathode metal layer are plated by plating on the parts to which the metal fine particles are applied. A method for manufacturing a chip-shaped solid electrolytic capacitor, which is characterized by forming the same.