JPH03116812A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To prevent characteristical deterioration due to mechanical stress, and to obtain a chip type solid electrolytic capacitor suitable for surface packaging by a method wherein a capacitor element is housed in the main body of a case, both ends of which are opened, and a metal cap, which will electrically be connected to the anode lead of the capacitor element and a cathode surface, is attached to both sides of the case main body. CONSTITUTION:A capacitor element 1, having a solid electrolyte consisting of a conductive high molecule between foils, is housed in a square-shaped electrically insulative resin case main body 3, both ends of which are opened. One of the opened parts of the above-mentioned case main body 3, namely, the opened part on the side facing the cathode surface 2b of the capacitor element 1 is covered by a metal cap 4 which becomes a cathode side terminal. This metal cap 4 is electrically connected to the cathode surface 2 of the capacitor element 1 through bonding silver 5, for example. As the capacitor element is housed in an outer covering case as above-mentioned, the solid electrolyte is effectively protected from the mechanical stress coming from outside and the like. Also, as the cap becomes a solder-bonded part, the title capacitor can be surface-packaged on a printed substrate, using an automatic machine and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to solid electrolytic capacitors, and more particularly to a chip-type solid electrolytic capacitor using a conductive polymer as a solid electrolyte.

[Conventional technology]

When the solid electrolyte is a conductive polymer, for example, a capacitor element made of a rolled body of valve metal foil such as aluminum is immersed in a monomer such as pyrrole, and then this is electrically or chemically polymerized. Then, polypyrrole (solid electrolyte) is formed between the aluminum foils, and finally, by dipping or molding into a resin liquid, a resin exterior body is formed around the capacitor element.

[Problem to be solved by the invention]

However, solid electrolytes made of this type of conductive polymer are susceptible to mechanical stress. therefore.

If the capacitor element is coated with resin and stored in a high temperature atmosphere for a long time, the difference in expansion coefficient between the anodic oxide film and conductive polymer of the capacitor element and the resin outer body causes
Microscopic peeling occurs between each layer, causing impedance deterioration, especially in the high frequency range.

The present invention has been made in view of the above-mentioned conventional circumstances, and its object is to provide a chip-type solid electrolytic capacitor that does not suffer from characteristic deterioration due to mechanical stress and is suitable for surface mounting.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a capacitor element having a solid electrolyte made of a conductive polymer, a cathode surface formed on the solid electrolyte via a predetermined cathode lead layer, and an anode lead wire. is housed in a cylindrical case body made of electrically insulating resin that is open at both ends, and one opening of the case body is covered with a cathode side metal cap that is electrically connected to the cathode surface of the capacitor element. In addition, the other opening of the case body is covered with an anode-side metal cap that is electrically connected to the anode lead wire of the capacitor element.

In this case, preferably the cathode side metal cap is electrically connected to the cathode surface of the capacitor element via a conductive adhesive, and the anode side metal cap is welded to the anode lead wire.

When the capacitor element is housed in the case body, it is arranged so that a part of its cathode surface protrudes from one opening of the case body, and a predetermined position is placed on the cathode surface protruding from the opening. The solder skin layer may be formed using a conductive material (for example, silver paint).

[For production]

As described above, since the capacitor element is housed within the outer case, the solid electrolyte of the capacitor element is effectively protected from external mechanical stress. Furthermore, since the caps (or solder sheaths N) provided at both ends of the case body serve as solder bonding parts for the printed circuit board, surface mounting on the printed circuit board can be performed using an automatic machine or the like.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to FIGS. 1 and 2, this solid electrolytic capacitor includes a capacitor element 1 made of a wound body of, for example, valve metal foil, and having a solid electrolyte made of a conductive polymer between the layers. .

Here, an example of a method for manufacturing this capacitor element 1 will be explained. First, an anodized film is formed on an etched electrode foil made of a valve metal foil such as aluminum in an aqueous solution containing, for example, adipic acid, and then cut into a predetermined length. After the anode lead wire 2a is attached to a predetermined portion of the electrode foil, separators are stacked on top of each other and the electrode foil is wound into a spiral shape.

Next, after carbonizing the separator at 2°0 to 400°C,
Reconstitution is performed with an aqueous ammonium adipate solution. and.

After being immersed in an aqueous solution of a conductive polymer (eg, pyrrole) monomer, it is immersed in an oxidizing agent containing ammonium persulfate or the like for a predetermined time to form a solid electrolyte of the conductive polymer. Furthermore, it is immersed in an aqueous solution containing a conductive monomer and toluenesulfonic acid.

Electrochemically polymerized to form a polymer (solid electrolyte, e.g. polypyrrole) with good electrical conductivity.

After coating carbon (for example Hitazol AB-1 manufactured by Hitachi Powder Metallurgy) on this solid electrolyte, silver paste (
The cathode surface 2b is formed by applying IBGL-110 (manufactured by Fukuda Metal Co., Ltd.).

In this embodiment, a capacitor element 1 is housed in a rectangular cylindrical case body 3 made of electrically insulating resin and open at both ends. One opening of the case body 3, that is, the opening on the side facing the cathode surface 2b of the capacitor element 1, is covered with a metal cap 4 serving as a cathode terminal. This metal cap 4 is electrically connected to the cathode surface 2b of the capacitor element 1 via a conductive adhesive, in this example adhesive silver 5. Also, the attachment of the metal cap 4 to the case body 3 is as follows:
The other opening of the case body 3 is covered with a metal cap 6, which serves as the anode side terminal, preferably by crimping, but a suitable adhesive may also be used.

How to attach the metal cap 6 to the case body 3.

Similarly to the above, it is preferably crimped, but an appropriate adhesive may be used. According to this embodiment, the metal cap 6 is provided with a hole 6a through which the anode lead wire 2a is inserted. 2a is welded to the cap 6 at the hole 6a, and its excess portion is cut off.

FIG. 3 shows a modification in which the metal cap serving as the anode side terminal is modified. That is, this metal cap 6' is provided with a protrusion 6b that projects inside the case body 3. According to this, the anode lead wire 2a is cut short in advance and welded to the protrusion 6b. Thereafter, the capacitor element 1 is inserted into the case body 3, and the cathode side metal cap 4 is attached to the cathode side 2b in the same manner as in the above embodiment.

FIG. 4 shows a modification in which a solder skin 717 is formed in place of the negative m# cap 4 shown in the embodiment of FIG. That is, in the above embodiment, the cathode surface 2b of the capacitor element 1 does not necessarily need to protrude from the opening of the case body 3, but in this modification, a part of the cathode surface 2b is made to protrude from the opening of the case body 3. The protruding portion is undercoated with a conductive material, in this example silver paint 8, and an outer skin layer 7 made of solder is applied thereon.
We are trying to form a According to this.

Cost reduction can be achieved compared to metal caps.

In this invention, the capacitor element supporting a solid electrolyte of a conductive polymer is not limited to the foil-wound type capacitor element of the above embodiment, but also a capacitor made of a sintered body of valve metal powder. Also includes elements.

〔Effect of the invention〕

As explained above, according to the present invention, a capacitor element having a solid electrolyte made of a conductive polymer is housed in a case body with both ends open, and an anode lead of the capacitor element is placed on both sides of the case body. By attaching a metal cap that is electrically connected to the cathode surface, the conductive polymer solid electrolyte can be effectively protected from external mechanical stress, and is suitable for surface mounting. A chip-type solid electrolytic capacitor is provided.

[Brief explanation of drawings]

All figures relate to embodiments of this invention. FIG. 1 is a perspective view showing a capacitor element and a case body housing the capacitor element separated, FIG. 2 is a sectional view of the solid electrolytic capacitor according to the first embodiment, and FIGS. 3 and 4 are FIG. 6 is a cross-sectional view showing a modification of the same solid electrolytic capacitor. In the figure, 1 is a capacitor element, 2a is an anode lead wire, 2b
is the cathode surface, 3 is the case body, 4 and 6 are the metal caps, 5
7 is adhesive silver and 7 is solder outer skin layer.

Claims (3)

[Claims] (1) A capacitor element having a solid electrolyte made of a conductive polymer, a cathode surface formed on the solid electrolyte via a predetermined cathode lead layer, and an anode lead wire, and both ends made of an electrically insulating resin. is housed in an open cylindrical case body, and one opening of the case body is covered with a cathode side metal cap electrically connected to the cathode surface of the capacitor element, and the other opening of the case body is A solid electrolytic capacitor characterized in that the opening is covered with an anode-side metal cap electrically connected to the anode lead wire of the capacitor element. (2) The solid state according to claim 1, wherein the cathode side metal cap is electrically connected to the cathode surface of the capacitor element via a conductive adhesive, and the anode side metal cap is welded to the anode lead wire. Electrolytic capacitor. (3) A capacitor element having a solid electrolyte made of a conductive polymer, a cathode surface formed on the solid electrolyte via a predetermined cathode lead layer, and an anode lead wire, with both ends made of an electrically insulating resin. is arranged in an open cylindrical case body so that a part of its cathode surface protrudes from one opening of the case body, and a predetermined conductive material is placed on the cathode surface protruding from the opening. A solid electrolytic capacitor characterized in that a solder skin layer is formed through the capacitor, and the other opening of the case body is covered with an anode-side metal cap electrically connected to the anode lead wire of the capacitor element. .