JPH02159714A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To contrive to sharply improve the reject rate of aging and a leakage current by a method wherein a lead terminal is attached to the inside of an electrode foil when viewed from the winding core side of a capacitor element. CONSTITUTION:Lead terminals 4 and 4 are attached to the side of inner surfaces 2b and 3b of electrode foil 2 and 3 when viewed from the winding core side of capacitor element 1'. The lead terminals 4 are arranged on the outer surface side of a separator 5 which is wound helically, and there is no possibility of intrusion of the edge of the lead terminals into the separator 5. Accordingly, the separator 5 is carbonized without having uneasiness about breakage, a heterocyclic compound polymer solution and the like such as a pyrrole monomer solution, thiophene monomer solution or polyfuran and the like is impregnated into the separator 5, and a more larger quantity of the solid electrolyte consisting of a conductivity high molecule, which is polymerized by an oxidizing agent, can be contained. As a result, a solid electrolytic capacitor having the small leakage current generating when an aging treatment is conducted can be obtained, and the reject rate can also be improved sharply.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solid electrolytic capacitor, and more specifically, to a solid electrolytic capacitor having a capacitor element made of a wound body of electrode foil.

[Conventional technology]

FIG. 3 shows a wound capacitor element 1 used in this type of solid electrolytic capacitor, and FIG. 4 schematically illustrates its cross section.

That is, this capacitor element 1 includes a pair of electrode foils 2 and 3 made of a valve metal such as aluminum.

Each electrode foil 2, 3 is etched, for example, to form a chemical conversion film on its surface, and then a lead terminal 4.4 in the form of a tab terminal, for example, is attached to a predetermined portion by caulking or the like. A capacitor element 1 is formed by spirally winding each electrode foil 2 and 3 with a separator 5 in between.
A solid electrolyte is then formed on this capacitor element 1.

[Problem to be solved by the invention]

As described above, the wound capacitor element 1 is formed. Conventionally, the lead terminals 4, 4 are connected to the outer surface 2a of the electrode foils 2, 3 when viewed from the winding core side of the capacitor element 1. , 3a side. Therefore, as clearly shown in FIG. 5, the edges of the lead terminals 4 may dig into the separator 5 and break through it. In particular, when the separator 5 is carbonized with the intention of increasing the amount of solid electrolyte retained, the separator 5 itself becomes brittle and is easily damaged, which causes leakage current deterioration defects.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a solid electrolytic capacitor comprising a capacitor element in which a pair of electrode foils to which lead terminals are attached are wound around a separator, and a solid electrolyte is formed on the capacitor element. In this case, the lead terminal is attached to the inside/surface side of the electrode foil when viewed from the core side of the capacitor element.

[For production]

According to the above configuration, since the lead terminals are arranged on the outer surface side of the separator, they are not damaged at the edges.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2. In these figures, the same parts as in FIG. 4 described earlier are given the same reference numerals.

In this capacitor element 1', lead terminals 4, 4
When viewed from the winding core side of the same capacitor element 1', each electrode foil 2,
It is attached to the inner surfaces 2b and 3b of 3. This attachment means may be crimping or welding, which are known per se.

According to this, as clearly shown in FIG. 2, the lead terminals 4 are arranged on the outer surface side of the separator 5 wound spirally, and there is no possibility that the edges will dig into the separator 5. do not have.

Therefore, the separator 5 can be carbonized without fear of damage.
The separator 5 can be impregnated with a virol monomer solution, a thiophene monomer solution, or a heterocyclic polymer solution such as polyfuran, so that it can contain a larger amount of a solid electrolyte made of a conductive polymer polymerized with an oxidizing agent. Note that this capacitor element 1' is housed in an exterior case and is finished as a discrete type or a chip type.

Using this capacitor element 1', the rated voltage is 25V.

A 0.22PF solid electrolytic capacitor (product of the present invention) was prototyped, and a conventional product with the same rating and capacity was used as a comparative example, and the defective rate and leakage current value during aging were measured. The results are shown in the table below. □ (Table) Number of samples measured: 100 each As is clear from this table, according to the present invention, both the defect rate during aging and the leakage current were significantly improved.

Furthermore, Fig. 6 shows the leakage current drop characteristics of the product of the present invention, and Fig. 7 shows the leakage current drop characteristics of the conventional product. It was confirmed that the wheels were rapidly lowering while drawing a beautiful curve. Noise defects have also been improved. .
5 [Effects of the Invention] As explained above, according to the present invention, the lead terminal is attached to the inner surface of the electric flute when viewed from the winding core side of the capacitor element, and the lead terminal is attached to the outer surface of the electric flute when viewed from the separator. By arranging it on the side, the separator will not be damaged at its edges. Therefore, a solid electrolytic capacitor with extremely small leakage current during aging can be obtained, and the defective rate can be significantly improved.

[Brief explanation of the drawing]

Fig. 1' is a schematic cross-sectional view showing an embodiment of a capacitor element according to the present invention, Fig. 2 is an enlarged sectional view of the main part thereof, and Fig. 3 is a general cross-sectional view of a wound type capacitor element. Fig. 4 is a cross-sectional view thereof, Fig. 5 is a partially enlarged sectional view of Fig. 4, Fig. 6 is a graph showing the leakage current drop characteristics of the product of the present invention, and Fig. 7 is a graph of the conventional product. 3 is a graph showing leakage current drop characteristics. In the figure, 1. ,． 1' is a wound type capacitor element, 2.3 is an electrode foil, 4 is a lead terminal, and 5 is a separator. N “0 tE tun! i tun

Claims (2)

[Claims] (1) A solid electrolytic capacitor comprising a capacitor element in which a pair of electrode foils to which lead terminals are attached are wound with a separator in between, and a solid electrolyte is formed in the capacitor element. A solid electrolytic capacitor, characterized in that the solid electrolytic capacitor is attached to the inner surface of the electrode foil when viewed from the winding core side of the element. (2) The separator is carbonized, and a solid electrolyte made of a polymer of a heterocyclic compound is retained therein.
The solid electrolytic capacitor described.