JPH04206621A - Solid electrolytic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a solid electrolytic capacitor which is thin and whose electrostatic capacity is large by a method wherein bending parts are formed at an anode lead, several electrode foils are attached, the bending parts are bent to be a zigzag shape and adjacent electrode foils are faced. CONSTITUTION:Bending parts 11 are formed at an anode lead 10; electrode foils 2 on which an oxide film has been formed on their surface are attached to foil-attaching parts 12a, 12b, 12c. Then, the anode lead 10 is bent to be a zigzag shape at the bending parts; adjacent electrode foils 2, 2 are faced so as to be a laminate shape. Then, a solid electrolyte composed of, e.g. polypyrrole is formed on the surface of the individual electrode foils 2; a cathode layer which is composed of carbon and a silver layer is formed between the individual electrode foils 2. Consequently, a mechanical stress exerted on the electrode foils 2 when the lead is bent is reduced, and it is possible to obtain a solid electrolytic capacitor which is flat and thin and whose electrostatic capacity is large.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a solid electrolytic capacitor, and more specifically, to a flat solid electrolytic capacitor in which the electrode foil is used as a flat plate, and a manufacturing method suitable therefor. It is.

[Conventional technology]

A capacitor element using a plate-shaped electrode foil is f
The thickness can be made thinner than the fi-wound type or the metal powder sintered body. FIG. 3 shows the flat capacitor element 1 as an example.

That is, this capacitor element 1 includes an electrode foil 2 made of a flat aluminum foil. An anode lead 3 is attached to a predetermined portion of this electrode foil 2. In this case, the anode lead 3 includes a flat plate part 3a as a foil attachment part and a rod-shaped lead leg 3b connected to one end of the plate part 3a, and the flat plate part 3a is attached to the electrode foil 2 by caulking or ultrasonic welding. Installed.

A solid electrolyte 4 made of a conductive polymer (for example, polypyrrole) is formed around the electrode foil 2, and a cathode layer 7 made of a carbon layer 5 and silver Jm 6 is formed thereon. Although not shown, a cathode lead is attached to this cathode layer 7 with a conductive adhesive such as adhesive silver.

Here, to explain the method of forming the solid electrolyte 3 using polypyrrole as an example, first, a pyrrole monomer is uniformly applied to the electrode foil 2 having an oxide film to which the anode electrode 3 is attached.

An oxidized polymer film is formed by immersing it in a solution containing a predetermined oxidizing agent. Next, electrolytic polymerization is carried out in an electrolytic solution containing a supporting electrolyte and a pyrrole monomer, using the oxidized polymeric membrane as an anode, to form an electrolytic polymeric membrane made of polypyrrole on the oxidized polymeric membrane.

[Problem to be solved by the invention]

By using such a capacitor element 1, a thin solid electrolytic capacitor can be obtained, but since it is composed of a single foil and its area is limited, a very high capacitance cannot be obtained.

Therefore, after forming a solid electrolyte (polypyrrole) on foil the size of several sheets, we folded it into a zigzag shape, for example.
If an attempt is made to obtain a capacitor element that is flat as a whole, the oxide film or polypyrrole will crack or peel off when the capacitor element is bent, resulting in a drawback that leakage current failures will occur frequently.

[Means to solve the problem]

The present invention has been made in view of the above-mentioned conventional circumstances, and the structural feature in claim 1 is that an anode lead is attached to a predetermined part of a flat electrode foil, and a conductive polymer is formed around the electrode foil. In a solid electrolytic capacitor having a flat capacitor element formed by forming a solid electrolyte and forming a cathode layer made of carbon, silver, etc. on the solid electrolyte, the capacitor element is bendable through a bending part. an anode lead having a plurality of interconnected foil attachment parts;
A plurality of electrode foils are attached to each foil attachment part of the same anode lead, and each electrode foil is formed into a laminated structure by bending each of the foil attachment parts from the bending part so that adjacent foil attachment parts face each other. The solid electrolyte and the cathode layer are formed on the surface and between the electrode foils, and the cathode lead is attached to the cathode layer via a conductive adhesive, and the capacitor element There is an exterior member provided around the .

In this case, according to a second aspect of the present invention, the bent portion includes a constricted portion, a through hole, or a thin groove portion formed between each foil attaching portion. According to a third aspect of the present invention, the exterior member is formed of a bottomed rectangular cylindrical exterior case, and the anode lead and the cathode lead are pulled out in the same direction from the opening side of the exterior case.

On the other hand, in the manufacturing method of claim 4, a plurality of foil attachment portions are formed on the anode lead via the bent portions, an electrode foil is attached to each of the foil attachment portions, and then the bent portions are bent to form each of the foil attachment portions. Electrode foils are stacked to face each other, and a solid electrolyte made of conductive polymer is formed on the surface of the foils. A cathode layer of carbon, silver, etc. is formed between each electrode foil, and the cathode layer is made of conductive material. The device is characterized in that the cathode lead is attached via an adhesive, and then the exterior member is provided.

[For production]

According to the above configuration, when each electrode foil is put into a laminated state, the anode lead is bent from the bent portion, so that the mechanical stress applied to the electrode foil is reduced.

Moreover, it can be manufactured through a series of work steps.

[Example] First, an anode lead 10 as shown in FIG. 1 is prepared. That is, this anode lead 10 is connected to a plurality of foil attachment parts 12a to 12c, three in this example, through a bending part 11 that facilitates bending, and to a foil attachment part 12c located on the outside. The lead leg 13 is provided with a lead leg 13. in this case.

The bent portion 11 is formed in a constricted shape as a flawed portion between each foil plate attached portion, but instead of this, for example, a hole may be bored in the same portion or the same portion may be made thin to facilitate bending. good.

With each foil attachment part 12a to 12c extended straight,
An electrode foil 2 is attached to each of them. An oxide film is formed on the electrode foil 2 in advance, and the electrode foil 2 is attached by welding or caulking. Next, as shown in FIG. 2, each of the foil attachment parts 12a to 12c is bent through the two bending parts 11, 11 so that adjacent ones thereof face each other. That is, the foil attachment part 12a and the foil attachment part 12b are connected to each other, and the foil attachment part 12b and the foil attachment part 12
c are bent in a zigzag shape at an angle of approximately 180 degrees so that they face each other. As a result, the surfaces of each electrode foil 2 face each other at a predetermined interval, forming a laminated state.

Thereafter, a solid electrolyte made of polypyrrole, for example, is formed on the surface of each electrode foil 2, and subsequently, a cathode layer made of carbon and silver is formed between each electrode foil 2. Note that the solid electrolyte and cathode layer are not shown in Fig. 2 for convenience of drawing, but these will be explained in Section 3 of the explanation above.
I would like to refer to the diagram. After forming the cathode layer, a cathode lead 14 is attached to the cathode layer via a conductive adhesive (not shown).
can be installed.

In this way, a capacitor element C in which three electrode foils 2 are laminated is obtained. This capacitor element C is housed in an outer case 15 having a square tube shape with a bottom, and is fixed within the outer case 15 with a sealing resin such as epoxy resin. In the case of a chip type, each lead 10, 14 is bent along the bottom wall surface of the outer case 15.

In the above embodiment, the solid electrolyte is formed on each electrode foil 2 after the foil attachment parts 12a to 12c are bent, but in some cases, the solid electrolyte may be formed in the state shown in FIG. 1 before being bent. In addition, although the capacitor element C is housed in the exterior case 15 in the above embodiment, the exterior member can also be formed by resin molding or immersion in a resin liquid. However,
In the case of resin molding, preferably the cathode lead 1
4 is pulled out in the opposite direction to the anode lead 10.

Here, the results of measuring the capacitance and equal series resistance (E S R) of the conventional product with one electrode foil and the inventive product with two and three electrode foils are shown below. Shown in the table.

(Table) As described above, it was demonstrated that by using a plurality of electrode foils, the capacitance increases and at the same time, the contact area is large, so that the equal series resistance also decreases.

〔Effect of the invention〕

As explained above, according to the present invention, a plurality of foil attachment portions are formed on the anode lead, an electrode foil is attached to each of the foil attachment portions, and an electrode foil is attached to each of the foil attachment portions.
By bending the portions between the foil plate attachment portions, mechanical stress on each electrode foil can be minimized. Therefore, a solid electrolytic capacitor with good characteristics despite being flat can be obtained.

[Brief explanation of the drawing]

1 and 2 relate to embodiments of the present invention,
Figure 1 is a perspective view showing the electrode foil attached to the foil attachment part of the anode lead, and Figure 2 shows a capacitor element formed by bending the anode lead in a zigzag shape between the foil attachment parts. A perspective view showing the exterior case for storage separated;
FIG. 3 is a perspective view showing a flat capacitor element with its constituent elements cut away. In the figure, 1 is a capacitor element, 2 is an electrode foil, 3 is an anode lead, 4 is a solid electrolyte, 5 is a carbon layer, 6 is a silver layer, 7 is a cathode layer, 10 is an anode lead, 11 is a bent part, 12 13 is a foil attachment part, 13 is a lead leg, 14 is a cathode lead, and 15 is an exterior case.

Claims (4)

[Claims] (1) Attach an anode lead to a predetermined part of a flat electrode foil, form a solid electrolyte made of a conductive polymer around the electrode foil, and a cathode layer made of carbon, silver, etc. on the solid electrolyte. In the solid electrolytic capacitor having a flat capacitor element, the capacitor element includes an anode lead having a plurality of foil attachment parts that are bendably connected via a bending part, and each foil of the anode lead. a plurality of electrode foils attached to the mounting portions, each of the electrode foils being arranged in a laminated manner by bending each of the foil mounting portions from the bending portion so that adjacent foil mounting portions face each other; The solid electrolyte and a cathode layer are formed on the surface of each electrode foil and between the foils, a cathode lead is attached to the cathode layer via a conductive adhesive, and an exterior is provided around the capacitor element. A solid electrolytic capacitor characterized by comprising: (2) The solid electrolytic capacitor according to claim 1, wherein the bent portion comprises a defect formed between the foil attachment portions. (3) The solid electrolytic electrolyte according to claim 1, wherein the exterior member comprises a bottomed square cylindrical exterior case, and the anode lead and the cathode lead are pulled out in the same direction from the opening side of the exterior case. capacitor. (4) Form a plurality of foil attachment parts on the anode lead via the bent parts, attach electrode foil to each of the foil attachment parts, and then bend the bent parts to face each electrode foil in a stacked manner. A solid electrolyte made of conductive polymer is formed on the surface of these foils, and a cathode layer of carbon, silver, etc. is formed between each electrode foil, and a cathode lead is attached to the cathode layer via a conductive adhesive. 1. A method for manufacturing a solid electrolytic capacitor, which comprises: attaching a capacitor, and then providing an exterior member.