JPH05217811A - Chip-shaped solid electrolytic capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To make the leakage current value of the title capacitor good by a method wherein metal sheets are used as spacers between anode parts for anode base bodies, through holes are made in the anode parts and the metal bodies and the anode bodies and the metal bodies are bonded by using a conductive material via the through holes. CONSTITUTION:Individual capacitor elements are mounted and arranged in such a way that holes 7 in anode parts 3 for the capacitor elements 2 coincide at least partly with holes 7 in metal sheets 8; after that, a conductive material 6 is injected so as to bury the holes 7; in addition, the conductive material is dried and hardened; the capacitor elements are united and laminated. Then, the bottom part of a conductor- layer formation part 4 for the laminated capacitor elements 2 and the metal sheets 8 are mounted and arranged on protrusion parts 1b, 1a at individual lead frames; they are connected electrically and mechanically by using a conductive paste or the like. Then, the solid electrolytic capacitor elements connected to the lead frames are sealed and molded by using an outer-package resin 5; after that, the protrusion parts at the lead frames are cut near the capacitor elements. Thereby, it is possible to obtain a chip-shaped solid electrolytic capacitor whose leakage current is good.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art As electronic devices become lighter, thinner, shorter, and smaller, miniaturization is also required for solid electrolytic capacitors, which is one type of electronic component used for the electronic devices. Generally, a laminated type as shown in FIG. 3 is used. The chip shape meets the demand for miniaturization.

FIG. 1 is a perspective view showing a conventional solid electrolytic capacitor having a chip shape. A plurality of solid electrolytic capacitor elements 2 inside an exterior resin 5 are arranged in the same direction, and The anode part 3 and the bottom surface of the conductor layer forming part 4 formed on the surface of the element are paired so as to face each other. It shows a state in which it is placed on the portion 1b and joined to it, and is sealed by a separately prepared exterior resin 5 such as an epoxy resin.

[0004]

In the conductor layer forming portion of the capacitor element described above, since the semiconductor layer and the conductor layer are laminated on the surface of the anode substrate such as aluminum foil,
It is thicker than the anode part. Therefore, this difference in thickness becomes more remarkable when a plurality of capacitor elements, for example, the conductor layer forming portions are stacked, and in extreme cases, a gap is generated between the anode portions.

In order to prevent the existence of such a gap, it is conceivable to insert a spacer having a thickness similar to that of the gap, but it is difficult to sufficiently connect the spacer and the anode part, and therefore, sealing molding is performed with an exterior resin. However, there is a problem that the exterior resin enters the gap between the spacer and the anode portion, and as a result, the leakage current of the produced solid electrolytic capacitor is increased.

[0006]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, provided a metal plate between the anode parts of each capacitor element and laminated the anode part and the metal plate. Then, it was found that the solid electrolytic capacitor in which the through holes communicating with each other were filled with a conductive material and laminated and connected had a good leakage current value, and the present invention was completed.

That is, the gist of the present invention is to use the end of an anode substrate made of a flat valve metal having a dielectric oxide film layer on the surface as an anode part, and the remainder of the anode substrate on the dielectric oxide film layer. In the semiconductor layer, the anode portion and the conductor layer forming portion of a plurality of solid electrolytic capacitor elements having a conductor layer forming portion on which a conductor layer is formed are respectively laminated and connected to a lead terminal, In a solid electrolytic capacitor that is sealed and molded with exterior resin,

A metal plate is fitted and inserted between the anode part and the anode part of each of the solid electrolytic capacitor elements and the lead terminal so that the anode part and the metal plate are electrically connected to each other. The anode part and the metal plate have through holes communicating with each other in a laminated state, and there is a chip-shaped solid electrolytic capacitor in which a conductive material is filled in the through holes,

Further, the chip-shaped solid electrolytic capacitor has an outer peripheral portion of the laminated anode portions covered with a conductive paste.

Further, an anode portion having a through hole is provided at an end of an anode base made of a flat valve metal having a dielectric oxide coating layer on the surface, and the remaining dielectric oxide coating layer of the anode base is provided. A solid electrolytic capacitor element having a semiconductor layer thereon and a conductor layer formed thereon to have a conductor layer forming portion is joined, and a metal plate having through-holes through which the through-holes communicate with each other in a state of being stacked on the anode portion is joined. After that, a plurality of these elements are stacked so that the through holes of the anode part and the metal plate are all in communication, and the through holes are filled with a conductive material, and the metal plate of the anode part and the conductor layer forming part are formed. It is a method of manufacturing a chip solid electrolytic capacitor in which lead terminals are connected to

The through hole of the anode part may be provided after forming the semiconductor layer or after forming the conductor layer, and after covering the outer peripheral part of the anode part of the laminated solid electrolytic capacitor element with a conductive paste. , A method of manufacturing a chip solid electrolytic capacitor which is sealed with an exterior resin.

The present invention will be described in detail below. As the anode substrate having a valve action which is used as the anode of the solid electrolytic capacitor in the present invention, any metal having a valve action such as aluminum, tantalum, and an alloy having these as a substrate can be used. The shape of the anode substrate may be a flat aluminum foil or plate.

The dielectric oxide film layer provided on the surface of the anode substrate may be an oxide layer of the valve action metal itself provided on the surface portion of the valve action metal, or on the surface of the valve action metal foil. It may be another dielectric oxide layer provided,
In particular, a layer made of an oxide of the valve metal itself is desirable.

In the present invention, the anode part is provided in one section of the end portion of the flat plate-shaped anode substrate having the dielectric oxide film layer formed on the surface thereof, and the through hole is provided at a predetermined position of the anode part. It is essential to be present. The through holes may be provided before or after the formation of the dielectric oxide film layer on the anode substrate, or may be provided before or after the formation of the semiconductor layer or the conductor layer, which will be described later, or in the intermediate process. The size of the holes depends on the size of the anode part and the number of laminated anode substrates, and is determined by preliminary experiments. The shape of the holes may be any known shape such as a circle, a quadrangle, and an ellipse. The number of holes may be plural.

Next, in the present invention, a metal plate having a through hole is placed at a predetermined position on the anode part so that at least the hole of the anode part is aligned with a part of the hole,
It is preferable that the holes of the metal plate are larger than the holes of the anode part because they are mechanically and electrically joined by welding or the like at the portions without holes. The time when the anode part and the metal plate are placed and bonded may be before or after the formation of the dielectric oxide film layer on the anode part, before or after the formation of the semiconductor layer or the conductor layer, or in the middle thereof. The shape of the holes of the metal plate may be any known shape such as a circle, a quadrangle, and an ellipse.

Examples of the material of the metal plate used include iron, nickel, copper, and alloys thereof, and it is preferable that the thickness thereof is approximately the same as the thickness of the semiconductor layer and the conductor layer described later. Although determined by preliminary experiments,
It is usually a metal foil of 0.05 mm to 1 mm. The size of the metal plate is about the same as the size of the anode part,
It is designed so as not to come into contact with the conductor layer forming portion of the capacitor element. The joining of the anode part and the metal plate is performed by welding or the like.

Next, a semiconductor layer is formed on the remaining dielectric oxide film layer other than the anode portion, but the kind of semiconductor layer is not particularly limited, and a conventionally known semiconductor layer can be used. In particular, a semiconductor layer composed of lead dioxide or lead dioxide and lead sulfate according to the applicant's application (Japanese Patent Laid-Open No. 62-2
56423, JP-A-63-51621)
However, the high frequency performance of the produced solid electrolytic capacitor is favorable, which is preferable.

Also, a method of forming a complex of tetrathiotetracene and chloranil as a semiconductor layer (Japanese Patent Laid-Open No. 62-62-62).
29123) or a reaction mother liquor containing thallium ions and persulfate ions to chemically deposit thallium oxide as a semiconductor layer (JP-A-62-38715).
(Gazette) is one example.

On such a semiconductor layer, a known conductive paste such as carbon paste and / or silver paste is laminated to form a conductive layer to form a conductive layer forming portion.

Next, a method of laminating a plurality of capacitor elements having conductor layers formed in this way will be described. FIG. 2 is a cross-sectional view showing a state in which the laminated capacitor elements are joined by the conductive material 6.

In the figure, after placing each capacitor element so that the hole 7 of the anode portion 3 of the capacitor element 2 at least partially matches the hole 7 of the metal plate 8, the hole 7 is filled with the conductive material 6. In this way, the capacitor element is integrally laminated by injecting and further drying and curing. In order to further strengthen the connection between each capacitor element 2, the laminated capacitor elements are integrated by immersing only the conductor layer forming portion of each capacitor element in a conductive material bath such as silver paste and drying and hardening. You can measure it. Examples of the above-mentioned conductive material 6 include known conductive paste such as silver paste, and meltable metal such as cream solder.

FIG. 1 is a perspective view showing a state in which the above-mentioned laminated capacitor elements are placed on a lead frame and connected to lead terminals. The bottom of the conductor layer forming portion 4 of the laminated capacitor element 2 and the metal plate 8 are placed on the protrusions 1b and 1a of the lead frame, respectively, and are electrically and mechanically connected by a conductive paste or the like.

The solid electrolytic capacitor element thus connected to the lead frame is sealed and molded by a transfer molding machine or the like with the exterior resin 5 such as an epoxy resin, and then the convex portion of the lead frame is placed near the capacitor element. It is cut by to make a chip-shaped solid electrolytic capacitor.

[0024]

By providing a through hole in the anode part of the capacitor element and placing the same so that at least a part of the hole of the anode part is aligned with a part of the hole of the metal plate having the through hole, a part without a hole is formed. , Then each capacitor element is aligned in the same direction and stacked, and the conductive material is bonded through the holes of each capacitor element, which improves the bonding between the anode part and the metal plate.
The gap between the anode part and the metal foil is reduced.

[0025]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. Examples 1 to 3 Small pieces of 45 μF / cm ² aluminum etching foil (hereinafter referred to as chemical conversion foil) having a dielectric oxide film layer formed on the surface by chemical conversion treatment in phosphoric acid and ammonium phosphate aqueous solution 5 × 3 mm. Prepared. 2 × 3 from the edge of this formed foil
The mm portion was used as the anode portion, and through holes of each size were provided at the positions shown in Table 1.

On the other hand, separately prepared nickel foil having a thickness of 0.1 mm, a size of 1.5 × 3 mm, and a hole size shown in Table 1 was prepared, and the chemical conversion foil and the metal were made so that the centers of the holes overlap. The foils were stacked, and the anode part of the formed foil and the metal foil were connected by spot welding at the portion without holes. The remaining 3 × 3 mm portion of the formed foil excluding the anode portion is 2.4 mol of lead acetate trihydrate /
It was immersed in a mixed solution of an aqueous solution of 1 and an aqueous solution of ammonium persulfate of 4.0 mol / l and left at 60 ° C. for 20 minutes to form a semiconductor layer composed of lead dioxide and lead sulfate.

After performing such an operation three times, a carbon paste and a silver paste were sequentially laminated on the semiconductor layer to form a conductor layer, and a capacitor element was manufactured. Four such capacitor elements were aligned in the same direction, and laminated with a silver paste through the anode part and the hole portion of the metal foil to produce a laminated capacitor element.

Further, the conductor layer forming portion of the laminated capacitor element was immersed in a silver paste bath and dried and hardened to integrate the conductor layer forming portion. Next, the bottom of the conductor layer forming portion of the multilayer capacitor element and the metal foil at the bottom of the anode portion are placed on the respective convex portions of a separately prepared lead frame having a convex portion with a width of 3 mm, and silver paste is used. Electrically and mechanically connected. Then, transfer molding was performed using an epoxy resin to produce a chip solid electrolytic capacitor.

Examples 4 to 6 In Examples 1 to 3, the metal foil was made of 42 alloy, and the semiconductor layer was immersed in a 2.0 mol / l aqueous solution of lead acetate trihydrate and the chemical conversion foil was separately prepared. Chip-shaped solid electrolytic capacitors were produced in the same manner as in Examples 1 to 3 except that lead dioxide was electrochemically formed between the prepared cathode and platinum.

Comparative Example 1 Example 1 was repeated, except that a chemical conversion foil and a metal foil having no through holes were used, and four chemical conversion foils and metal foils were alternately superposed on each other and the anode part and the metal foil were spot-welded at the same time. The chip-shaped solid electrolytic capacitors were prepared in the same manner as in the above-mentioned Steps 3 to 3.

[0031]

[Table 1]

Table 2 shows the performance of the solid electrolytic capacitor immediately after being manufactured as described above. Each example or comparative example is an average value of all numerical values n = 50 points.

[0033]

[Table 2]

[0034]

The chip-shaped solid electrolytic capacitor of the present invention uses a metal plate as a spacer between the anode parts of the anode substrate and has through holes in the anode part and the metal plate. Since they are joined by the material, the manufactured solid electrolytic capacitor has a good leakage current value.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which laminated capacitor elements are placed on a lead frame and connected.

FIG. 2 is a cross-sectional view showing a state in which laminated capacitor elements are joined with a conductive material.

FIG. 3 is a perspective view showing a conventional multilayer chip solid electrolytic capacitor.

[Explanation of symbols]

 1a Projection of lead frame 1b Projection of lead frame 2 Capacitor element 3 Anode part 4 Conductor layer forming part 5 Exterior resin 6 Conductive material 7 Hole 8 Metal plate

Claims (5)

[Claims] 1. An end portion of an anode substrate made of a flat valve metal having a dielectric oxide film layer on its surface is used as an anode portion, and a semiconductor layer is formed on the remaining dielectric oxide film layer of the anode substrate. A plurality of solid electrolytic capacitor elements having a conductor layer forming portion on which a conductor layer is formed, the anode portion and the conductor layer forming portion are respectively laminated and connected to lead terminals, and sealed with an exterior resin. In the molded solid electrolytic capacitor, a metal plate is inserted between the anode part and the anode part of each of the solid electrolytic capacitor elements and the lead terminal to electrically connect the anode part and the metal plate. The chip-shaped solid electrolytic capacitor is characterized in that all the anode parts and the metal plates have through holes communicating with each other in a laminated state, and the through holes are filled with a conductive material. 2. The chip-shaped solid electrolytic capacitor according to claim 1, wherein an outer peripheral portion of the laminated anode portions is covered with a conductive paste. 3. An anode part having a through hole is provided at an end of an anode substrate made of a flat valve metal having a dielectric oxide film layer on the surface thereof, and the remaining dielectric oxide film layer of the anode substrate is provided. A solid electrolytic capacitor element having a semiconductor layer thereon and a conductor layer formed thereon to have a conductor layer forming portion is joined, and a metal plate having through-holes through which the through-holes communicate with each other in a state of being stacked on the anode portion is joined. After that, a plurality of these elements are stacked so that the through holes of the anode part and the metal plate are all in communication, and the through holes are filled with a conductive material, and the metal plate of the anode part and the conductor layer forming part are formed. A method of manufacturing a chip-shaped solid electrolytic capacitor, which comprises connecting lead terminals to and and sealing-molding with an exterior resin. 4. The method for producing a chip solid electrolytic capacitor according to claim 3, wherein the through hole of the anode portion is provided after the semiconductor layer is formed or after the conductor layer is formed. 5. The method according to claim 3, wherein after covering the outer peripheral portion of the anode portion of the laminated solid electrolytic capacitor element with a conductive paste, sealing molding is performed with an exterior resin.
A method for producing the chip-shaped solid electrolytic capacitor described.