JPH03196607A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To ensure the welding strength of a lead terminal by fastening an electrode foil in the folded portion of the lead terminal before welding. CONSTITUTION:An aluminum-based foil having a coarse surface is anodized to form a dielectric film. The foil with the dielectric film, as an electrode, is grasped in a folded portion 3 of a lead terminal 2. The folded portion is welded both sides to form an electrode l. The dielectric film of the electrode 1 is coated with conductive polymer film such as pyrrole, thiophene, aniline, or furan. This permits welding current to flow to the joint uniformly. Since the joint is under pressure, the welding proceeds while sponge-like stuff or the dielectric film on the electrode is removed. Therefore, a double-sided strong weld is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an aluminum solid electrolytic capacitor using a conductive polymer film such as polypyrrole as a solid electrolyte.

Conventional technology In conventional aluminum electrolytic capacitors using a solid electrolyte, a dielectric coating is formed by anodizing aluminum foil that has been roughened in advance, and various metal plates are connected to the aluminum electrodes with the dielectric coating formed thereon. The terminals were welded to form the electrodes, but in order to meet the demand for smaller solid electrolytic capacitors, the use of aluminum foil with a high surface roughening ratio is being considered. However, aluminum foil with a high roughening ratio has a thick spongy roughened part and a dielectric film is formed on its surface, so when it is connected to a lead terminal by welding, its strength is reduced. We cannot secure enough. Alternatively, in order to strengthen the welding strength, methods such as applying resin to the welded area are being considered.

Problems to be Solved by the Invention In solid electrolytic capacitors as described above, sufficient welding strength cannot be ensured, so aluminum foil with a high surface roughening ratio cannot be used, and there is a problem that miniaturization is not possible.

In addition, the method of reinforcing the welded portion with resin complicates the process, increases costs, and does not provide a stable reinforcing effect.

Means for Solving the Problems The present invention has solved the above-mentioned problems, and includes forming a dielectric film by anodizing a foil whose main component is aluminum, which has been roughened in advance, and an electrode on which this dielectric film is formed. The foil is held under pressure between the folded pieces at the end of the lead extraction terminal, and is welded from both the front and back sides of the folded lead extraction terminal to form an electrode. This is a solid electrolytic capacitor characterized by forming a conductive polymer film such as furan or the like and encasing it in resin.

Function: In the welding process of this invention, the welding current flows uniformly through the welding area, and the welding is carried out while being pressurized from both sides. Welding is performed while destroying the body coating, resulting in a strong weld. Also, since it is welded on both sides,
More stable welding strength can be ensured.

EXAMPLE An aluminum foil having a thickness of 150 .mu.m was subjected to alternating current etching in an aqueous hydrochloric acid solution, and etching was performed to a depth of 20 .mu.m on both the front and back sides as sample 1. Also sample-2
As a result, etching of 50 μm was performed on both the front and back sides of the aluminum foil. Furthermore, a dielectric film equivalent to 50 μm was formed in an aqueous solution of 7 ammonium dibate,
As shown in Figure 3, the lead-out terminal manufactured by the conventional welding method and the lead-out terminal that is pressurized and clamped between the folded pieces at the end of the lead-out terminal and folded back as shown in Figure 1 or 2. Electrodes were formed by welding from both the front and back sides, and the tensile strengths were compared. The results are shown in FIG. 4(A) (Sample 1) and FIG. 4(0) (Sample 2). Furthermore, a polypyrrole layer is formed on the dielectric layer of each of these electrodes, a carbon layer is further formed, and a cathode is drawn out using silver paste.
The oven was packaged with epoxy resin and the oven occurrence rate (number of oven occurrences/number of tests) was compared. The results are shown in Table 1.

It has been demonstrated that the welding strength of the present invention is high and that it can withstand the stress caused by the resin exterior.

Effects of the Invention As described above, a dielectric film is formed by anodizing aluminum foil that has been roughened in advance, and the electrode foil with the dielectric film formed thereon is clamped under pressure by folding back the end of a lead extraction terminal. , and an electrode is formed by welding the front and back sides of the folded lead-out terminal, and a conductive polymer film of pyrrole, thiophene, aniline, furan, etc. is formed on the dielectric film of the electrode, and the film is covered with resin. Solid electrolytic capacitors exhibit stable characteristics and have great industrial and practical value.

[Brief explanation of drawings]

The first factor and FIG. 2 are different embodiments of the connection portion between the electrode foil and the lead-out terminal according to the present invention, where (A) is the front side, (0) is the front side, and (0) is the front side.
is a perspective view of the back side, Figure 3 is a perspective view of the connection between the conventional electrode foil and the lead-out terminal, and Figure 4 (a) is the tensile strength of the lead-out terminal connection between the inventive product and the conventional product based on sample-1. FIG. 4(0) is a comparison diagram of the tensile strength of the pull-out terminal connection part between the product of the present invention and the conventional product based on Sample-2. 1 Ni Aluminum electrode 2: Output terminal 3.4: Folded cantilever of lead pullout end Applicant: Nichicon Corporation Figure 1 (A) Figure 2 (A) Figure 1 (B) Figure 2 (B) Figure 4 (a)

Claims (1)

[Claims] A dielectric coating is formed on a foil whose surface is mainly made of aluminum, which has been roughened in advance, by anodizing, and the electrode foil with the dielectric coating formed thereon is clamped under pressure between folded pieces at the ends of lead extraction terminals. Furthermore, an electrode is formed by welding the front and back sides of the folded lead-out terminal, and a conductive polymer film of pyrrole, thiophene, aniline, furan, etc. is formed on the dielectric film of the electrode, and the film is covered with resin. solid electrolytic capacitor.