JPH03241726A - Electrolytic capacitor - Google Patents

Abstract

PURPOSE:To enable the favorable impregnation with semiconductor of a capacitor element by providing the core of the capacitor element with space at least one-third the element diameter or more in diameter. CONSTITUTION:In an electrolytic capacitor, which is constituted by impregnating a capacitor element 6, where a spacer 3 is interposed between an anode foil 1 made of a value metal and a cathode foil 2 and they are rolled, with organic semiconductor 11, space 7 at least one-third the element diameter or more in diameter is provided in the core part of the capacitor element 6. Putting the diameter of the space 7 to the diameter one-third the element diameter or more is atributable to that the effect of improvement of the impregnation can not be gotten so much in the case where it is put to below one-third. Hereby, great capacitance high in impregnation of organic semiconductor and free of variation can be gotten.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrolytic capacitor using an organic semiconductor as a solid electrolyte, and particularly to an electrolytic capacitor with an improved element structure.

[Prior Art] In general, a dry foil electrolytic capacitor is constructed by connecting a pair of positive and negative electrode foils made of high-purity aluminum foil to a pair of lead terminals also made of aluminum, and
A capacitor element formed by winding cathode foils with a spacer interposed between them is impregnated with a driving electrolyte and housed in a case, the opening of the case is sealed, and an exterior is applied.

In the electrolytic capacitors described above, the driving electrolyte uses an organic carboxylic acid such as ammonium adipate in an organic solvent such as ethylene glycol, so there is a limit to the improvement of tan δ characteristics and There were problems that needed to be resolved in order to meet market demands, such as low resistance and extremely poor low-temperature characteristics, and lack of reliability for use over a wide temperature range.

Therefore, in recent years, instead of such driving electrolytes,
Various electrolytic capacitors using organic semiconductors consisting of TCNQ complexes have been proposed and are now being put into practical use.

Methods for impregnating capacitor elements with TCNQ complexes generally include solution impregnation methods, dispersion impregnation methods, and even vacuum evaporation methods, but the characteristics of TCNQ complexes change under various conditions and are extremely difficult to handle. Various measures have been taken for its use.

In particular, as conditions for the solid electrolyte, it is important that the resistance value itself, which affects tan δ as a capacitor characteristic and the equivalent series resistance, is small, and that the solid electrolyte has a stable resistivity value even under temperature, especially high temperatures.

By the way, as an impregnation means for industrially uniformly infiltrating the required amount of TCNQ complex into the inside of a capacitor element, heat melting and liquefaction treatment is proposed as described in several patent publications or technical documents that have been proposed in the past. is considered valid. The specific process of this heat-melting and liquefaction process involves placing a capacitor element that has been heated in advance in a desired TCNQ complex liquid that has been heated and melted in an exterior case, and then storing a capacitor element that has been heated in advance in a desired TCNQ complex liquid that has been heated and melted. The impregnation is carried out through etching pits.

In this step, when the capacitor element is housed, if the entire element is immersed in the TCNQ complex liquid, the impregnating properties of the capacitor element can be improved; however, normally, the method of immersing the entire element in the TCNQ complex liquid is Not adopted. In other words, the TCNQ complex has little film-repairing effect;
If the CNQ complex adheres to the unformed part of the anode side terminal, it will cause a fatal problem of short circuit failure, so generally, the amount of TCNQ complex is kept to the minimum necessary amount, and one end of the capacitor element (case Impregnation is performed using capillary action from the end surface (located at the inner bottom).

However, although the impregnation method described above is suitable when the element is relatively small, when the element becomes large, the distance from the impregnated end of the capacitor element to the other end becomes long. Disadvantages include that the TCNQ complex liquid hardens or decomposes before it is sufficiently impregnated into the entire capacitor element, resulting in failure to obtain the desired capacitance, increased loss, and increased leakage current. was occurring.

[Problems to be Solved by the Invention] As described in Section 2, conventional electrolytic capacitors have the disadvantage that capacitor elements cannot be sufficiently impregnated with organic semiconductors, resulting in a decrease in performance characteristics.

The present invention was proposed in order to solve the problems of the prior art, and its purpose is to achieve high impregnability with organic semiconductors, obtain a large capacitance with no variation, and improve loss characteristics and leakage. An object of the present invention is to provide an electrolytic capacitor with good current characteristics.

[Means for Solving the Problems] The electrolytic capacitor of the present invention is an electrolytic capacitor formed by impregnating an organic semiconductor into a capacitor element wound with a spacer interposed between an anode foil and a cathode foil made of a valve metal. The capacitor element is characterized in that the winding core thereof has a gap having a diameter of at least 1/3 or more of the element diameter.

[Function] In the present invention having the above-described configuration, by providing a void portion having a diameter of at least 1/3 of the element diameter in the winding core of the capacitor element, impregnation from the bottom of the cylindrical element is prevented. Since the properties can be greatly improved, it becomes possible to easily impregnate the capacitor element with a good semiconductor, and the causes of characteristic deterioration are eliminated.

In this case, the diameter of the cavity should be set to at least 1/3 of the element diameter.
The reason why the diameter is set to the above value is that if the diameter is less than 1/3, the effect of improving impregnability cannot be obtained much.

[Example] Below, a basic example of the electrolytic capacitor according to the present invention will be specifically described with reference to the drawings.

First, as shown in Fig. 2, the surface of the aluminum foil is roughened with an etching solution to increase the surface area, and then the anode foil 1 with an anodized film formed thereon and the aluminum foil surface are roughened with an etching solution in the same manner as described above to increase the surface area. A spacer 3 made of kraft paper or manila paper is interposed on the enlarged cathode foil 2, and an anode lead-out terminal 4 or a cathode lead-out terminal 5 is attached to an arbitrary part of the anode foil 1 and cathode foil 2, respectively. and wind it.

In this winding, at least one part of the diameter of the finished element is
The capacitor element 6 is formed using a cylindrical or cylindrical winding core having a diameter of /3 or more. After that, by removing the winding core, 1/3 of the element diameter is placed on the winding core of the capacitor element 6.
A cavity 7 having a circular cross-section having a diameter of -1- is formed. Next, as shown in FIG. 3, an organic semiconductor made of a TCNQ complex is placed in a double-opening aluminum case 8, and this organic semiconductor is heated and melted to form an organic semiconductor melt 9. As shown in FIG. 1, the capacitor element 6 is housed in the melt 9 in a preheated state, and the organic semiconductor melt 9 is impregnated into the capacitor element 6, and then cooled and hardened to form the upper opening of the case 8. The capacitor is completed by sealing the portion with a sealing body 10. Note that 11 in Figure 1
indicates the organic semiconductor after curing.

In the electrolytic capacitor of this embodiment as described above, first, the lower end surface of the capacitor element 6 is impregnated with the organic semiconductor melt 9 as in the conventional case, and the side surface of the capacitor element 6 and the case 8 are impregnated with the organic semiconductor melt 9. The injection is carried out from the gap with the side surface 1x, and also from the upper end surface of the capacitor element 6. In addition, in this embodiment, in particular, by forming a large gap 7 having a diameter of 1/3 or more of the element diameter in the winding core of the capacitor element 6, Because the organic semiconductor melt 9 is also
The entire capacitor element 6 will be impregnated by capillary action. Therefore, it is possible to perform sufficient and reliable impregnation in a shorter time than in the past, and it is possible to obtain a large capacitance without variation and improve loss characteristics. Furthermore, since the impregnation is completed in a short time, deterioration of the oxide film can be reduced, which can greatly contribute to improving leakage current characteristics.

Next, in order to explain the effects of the present invention more specifically, an electrolytic capacitor (inventive product A) with a constant rating was manufactured using electrode foil of a constant size according to the present invention, and As a comparative example, an electrolytic capacitor (conventional product B) having the same rating as the product A of the present invention was manufactured using an electrode foil having the same dimensions as the product A of the present invention according to the prior art. That is, the product A of the present invention includes an anode foil with a width of 5 mm and a length of 25 mm, and an anode foil with a width of 5 mm.
mm, using a cathode foil with a length of 35 mm, and a diameter of 2.5 mm.
A capacitor element having an element diameter of 5 mmφ was prepared by winding the capacitor with manila paper around a core of 5 mm in diameter. As Conventional Example B, an anode foil and a cathode foil having the same dimensions as those of the present invention were used and wound together with manila paper around a winding core having a diameter of 1 mm to produce a capacitor element having an element diameter of 4.5 mmφ. Except for the diameter of the winding core, both the invention product A and the conventional product B were constructed in exactly the same manner according to the process of the above embodiment.

In addition, as an organic semiconductor, N-methyl 3-n
A TCNQ complex of propylimidacil was used. Also,
The rating is 16Wv-10μF for both the invention product A and conventional product B.
It is.

Regarding the present invention product A and the conventional product B created as described above,
When we investigated the capacitance distribution, loss distribution, and leakage current distribution using a large number of samples, we found that Figs.
The results shown in the figure were obtained.

As is clear from these FIGS. 4 to 6, the product A of the present invention has better properties than the conventional product B in all characteristics.
It can be seen that it has excellent characteristics with little variation. In particular, as shown in FIGS. 4 and 5, an increase in capacitance,
The effect in reducing the loss is clear, and these prove the effect of improving the impregnability of the organic semiconductor by providing the void portion 7 in the winding core in the product of the present invention.

Note that the present invention is not limited to the above embodiments,
For example, the shape of the winding core, and therefore the shape of the void formed in the winding core, is not limited to a circular cross-section, and can be selected as appropriate, such as triangular, square, or other polygonal shapes. .

[Effects of the Invention] As explained above, in the present invention, by improving the extremely simple structure of providing a void portion having a diameter of at least 1/3 or more of the element diameter in the winding core of a capacitor element, this void can be reduced. Capillary action also occurs at the bottom of the cylindrical element, which greatly improves the impregnating property from the bottom of the cylindrical element, and the capacitor element can be sufficiently and reliably impregnated with the organic semiconductor in a short period of time. high,
It is possible to provide an electrolytic capacitor that can obtain a large capacitance without variation and has good loss characteristics and leakage current characteristics.

[Brief explanation of drawings]

1 to 3 are diagrams showing one embodiment of an electrolytic capacitor according to the present invention, in which FIG. 1 is a sectional view showing an electrolytic capacitor, and FIG. 2 is a diagram showing a capacitor element in the manufacturing process of the electrolytic capacitor shown in FIG. FIG. 3 is a developed perspective view showing a wound state, and FIG. 3 is a sectional view showing a state in which an organic semiconductor is placed in a case in the manufacturing process of the electrolytic capacitor shown in FIG. 4 to 6 are diagrams comparatively showing the characteristics of an electrolytic capacitor manufactured according to the present invention and an electrolytic capacitor manufactured according to the prior art, and FIG. 4 is a capacitance distribution diagram, and FIG.
The figure is a loss distribution diagram, and FIG. 6 is a leakage current distribution diagram. 1... Anode foil, 2... Cathode foil, 3... Spacer,
4... Anode lead-out terminal, 5... Cathode lead-out terminal, 6...
・Capacitor element, 7...Gap, 8...Case,
9... Organic semiconductor melt, 10... Sealing body, 11.
...Organic semiconductor. 1 Figure 3 Figure C

Claims (1)

[Claims] In an electrolytic capacitor in which a capacitor element is wound with a spacer interposed between an anode foil and a cathode foil made of a valve metal and impregnated with an organic semiconductor, the capacitor element has a winding core with a diameter of at least 1. An electrolytic capacitor characterized by having a cavity having a diameter of /3 or more.