JPH063786B2 - Method for manufacturing solid electrolytic capacitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a solid electrolytic capacitor using an organic semiconductor composed of a TCNQ salt as a solid electrolyte.

(B) Conventional Technology It is already known that an organic semiconductor composed of a TCNQ salt can be used as a solid electrolyte of a solid electrolytic capacitor. In this case, the solid electrolyte is directly attached to a film-forming metal such as aluminum having an oxide film, but as a different form, the anode foil and the cathode foil are wound with separator paper sandwiched between them to form a capacitor element. However, it is also possible to impregnate the separator paper in this element with the solid electrolyte described above in Japanese Patent Application No. 56-116861 (Japanese Patent Publication No. 62-52939).
01G9 / 02)) has already been proposed as an invention.
Incidentally, TCNQ means 7,7,8,8, tetracyanoquinodimethane.

In such a conventional technique, an organic semiconductor powder is appropriately pressed and packed in an aluminum case having good thermal conductivity, which is melted and liquefied at 250 to 300 ° C., and the capacitor element is preheated and dipped for impregnation. Then, the element is cooled and solidified together with the aluminum case, and completed through steps such as resin sealing and voltage treatment (aging).

By the way, although the oxide film which is a dielectric is formed on the anode of the capacitor element, the oxide film is damaged by thermal shock during element preheating and impregnation or mechanical shock during element transportation and impregnation. Therefore, after impregnation with the organic semiconductor or after sealing the resin, the oxide film is repaired, and voltage treatment (aging) is performed at a high temperature of about 100 ° C. for the purpose of reducing the leakage current value.

However, the solid electrolyte made of an organic semiconductor has a drawback that the repairability of an oxide film is weaker than that of an electrolytic solution used in a general electrolytic capacitor, and thus has a problem that the leakage current value is large and the yield is low.

(C) Problems to be Solved by the Invention The present invention has the above-mentioned problems in a solid electrolytic capacitor using an organic semiconductor composed of a TCNQ salt as a solid electrolyte, that is, the repairability of the oxide film of the solid electrolyte is weak and the leakage current value is It is a solution to the problem of a large low yield, and a capacitor anode element formed by pressure-molding or sintering a metal powder having a valve action such as aluminum, tantalum, niobium, etc. is made of TCNQ salt. It is intended to solve the same problems of oxide film repairability, leakage current, and yield as those described above in a solid electrolytic capacitor using an organic semiconductor as a solid electrolyte.

(D) Means for Solving the Problem The present invention is to press-mold a capacitor element formed by forming an anodized film on a film-forming metal, or a metal powder having a valve action such as aluminum, tantalum, and niobium. Of a solid electrolytic capacitor in which the anode element of a capacitor formed by sintering or sintering is impregnated with a melted and liquefied organic semiconductor, cooled and solidified, pure water is then impregnated inside the element, and then the moisture of the element is dried. It is a manufacturing method.

(E) Function By impregnating pure water into the element that has been impregnated with TCNQ salt and then drying it, the organic semiconductor that has entered the defective portion of the oxide film becomes easier to become an insulator, and the oxide film is restored by voltage treatment (aging). Significantly improved.

(F) Examples Hereinafter, the present invention will be described with reference to Examples. As an example of the present invention, a winding element (capacitor element) in which an aluminum foil for an anode (anode foil) and an aluminum foil for a cathode (cathode foil) are wound as a separator paper using a manila paper having a thickness of 50 μm.
In addition, as a solid electrolyte, N- (n-propyl) -quinolinium, N- (n-butyl) -isoquinolinium, N-
The production process using each TCNQ salt of (n-amyl) -isoquinolinium and N- (isoamyl) -isoquinolinium will be described.

First, the cut end of the anode foil of the winding element is formed by applying a voltage substantially the same as the anodizing voltage using a forming solution.
On the other hand, the TCN is placed in a cylindrical aluminum case with a bottom.
An appropriate amount of powder of Q salt is put, and the above case is heated and held on an iron plate kept at a melting point of TCNQ salt or higher, preferably 280 to 300 ° C. In addition, such a case finally becomes an envelope of the capacitor. The melting point of the above TCNQ salt is 2
The temperature is 10 to 230 ° C. Therefore, the TCNQ salt in the case is melted and liquefied by the above heating. In the subsequent step, the case is immediately cooled in this state to solidify the TCNQ salt. By such a step, the winding element is impregnated with the liquid TCNQ salt, and the TCNQ salt is recrystallized by the subsequent rapid cooling,
A solid electrolysis showing a high conductivity of 2 to 30 Ωcm (25 ° C) is formed.

In the subsequent step, the TCNQ salt-impregnated element is immersed in pure water, and the inside of the element is impregnated with pure water under reduced pressure. Further, in the next step, the moisture of the capacitor element is dried at 85 to 105 ° C. for 1 to 8 hours. The drying time is almost proportional to the outer diameter of the capacitor element. Finally, the opening of the case is sealed with resin or rubber. And 125 ° C
At about 1 hour, the rated voltage of the capacitor is applied (aged) to complete the solid electrolytic capacitor. The characteristic comparison data between the example of the present invention and the conventional example will be described below.

In Examples 1 to 4, after impregnating pure water into the capacitor element,
The capacitor element is dried at 3.5 ° C. for 3.5 to 4.5 hours and sealed with an epoxy resin.
No. 4 is a resin which has been sealed with epoxy resin after impregnating with TCNQ salt and without impregnating with pure water.

Table 2 shows the same rated voltage using the same TCNQ salt,
It is a comparison between an example of a solid electrolytic capacitor having a capacitance and a conventional one.

Cap. : Capacitance at 120 Hz tan δ: dielectric loss tangent at 120 Hz L. C. : Leakage current value (30 seconds after rated voltage application) ESR: Equivalent series resistance at 100KHz In Table 2, Example (2 ') and Conventional Example (2') are
(2) The same TCNQ salt as the conventional example (2). Each numerical value in Table 2 shows an average value of 10 values. C. Regarding the value, the average value of 10 non-defective products within the standard is shown. C. The yield of (1) indicates the yield of 100 samples each.

In addition, L. C. The standard is 25V, 3.3μF… 0.83μA / 30sec. Or less 10V, 220μF… 44μA / 30sec. Or less 35V, 4.7μF… 3.3μA / 30sec. Or less 16V, 15μF… 2.4μA / 30sec. Or less.

As is clear from Table 2, the example is compared with the conventional example in L.S. C. There is a significant difference in the yield of the product, and the effect of impregnating pure water is clearly visible.

Note that the present invention is not limited to the case where a winding element obtained by winding an anode foil and a cathode foil with separator paper as a capacitor element is used, and a metal powder having a valve action is pressure-molded as a capacitor element. It is also applied when using a sintered element that has been sintered.

Next, an example in which the present invention is applied to a sintered element will be described.
A capacitor element formed by implanting an aluminum lead wire for an anode in fine aluminum powder (particle size: about 10 to 40 μm) and sintering is used to electrochemically form an oxide film layer serving as a dielectric by using a chemical conversion liquid. A manufacturing process in the case where the same four types of TCNQ salts as those in the above-mentioned embodiment are used as the solid electrolyte in the capacitor element will be described.

First, the sintered aluminum capacitor element is anodized using a chemical conversion solution containing ammonium adipate. The formation voltage is about 100V to 200V (DC).
In this embodiment, since the element having the rated voltage of 25V and the rated electrostatic capacity of 1 μF is used, the formation voltage is 190V.

On the other hand, the TCN is placed in a cylindrical aluminum case with a bottom.
An appropriate amount of Q salt powder is put, and the above case is heated and held on an iron plate kept at a melting point of TCNQ or higher, preferably 280 ° C to 300 ° C. The melting point of the above TCNQ salt is 210 ° C to 2 ° C.
The temperature is 30 ° C, so the above heating causes TCN in the case.
The Q salt melts and liquefies.

In the subsequent step, the preheated capacitor element is immersed in the liquefied TCNQ salt in the case and impregnated with the TCNQ salt. In the next step, the capacitor element is immediately taken out of the case and rapidly cooled with air to solidify the TCNQ salt. By such a process, liquid TCNQ salt is impregnated inside the capacitor element, and TCNQ salt is then cooled by rapid cooling.
The salt recrystallizes to form a solid electrolyte exhibiting a high conductivity of 2-30 Ω, cm (25 ° C).

In the subsequent step, the TCNQ salt-impregnated element is immersed in pure water, and the pure water is impregnated into the element under a reduced pressure of about 20 mmHg.

Further, in the next step, the water content of the capacitor is dried at 85 ° C. to 105 ° C. for 1 hour to 8 hours. The drying time is almost proportional to the volume of the capacitor element, and in this embodiment, it is 8
Dry at 5 ° C for 5 hours. The device dimensions of this embodiment are 2.8 mm in diameter and 3.5 mm in length.

In a subsequent step, a silver paint conductive layer and a solder layer are formed, a lead wire for a cathode is led out, and a lead wire for an anode is welded to an aluminum lead which is erected in a capacitor element. Finally, the package is covered with epoxy resin, and the rated voltage of the capacitor is applied (aged) at 125 ° C. for 1 hour to complete the intended solid electrolytic capacitor.

Next, Tables 3 and 4 show characteristic comparison data between the examples of the present invention and the conventional example.

The initial characteristics in Table 4 are values at 20 ° C. C is a leakage current value (a value 30 seconds after the rated voltage (25 V) is applied and within the standard (0.5 μA / 30 sec)
Below, the average value of 10 non-defective products is shown. C. The yield indicates the yield of 100 samples each. The other items in Table 4 show average values of 10 pieces each.

FIG. 1 is a sectional view showing this embodiment. (1) is a capacitor element, (2) is an aluminum anode lead, (3) is an anode lead wire, (4) is a cathode lead wire, and (5) is an organic lead wire. A semiconductor, (6) is a silver paint conductive layer, (7) is a solder layer, and (8) is an epoxy resin.

(G) Effect of the Invention As described above, according to the present invention, in a solid electrolytic capacitor using an organic semiconductor as an electrolyte, water is impregnated,
Then, by a simple process of drying this, the leakage current can be reduced and the yield can be greatly improved, which greatly contributes to the practical application of such a solid electrolytic capacitor.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a sintered solid electrolytic capacitor of the present invention. (1) ... Capacitor element, (2) ... Aluminum anode lead, (3) ...
Anode lead wire, (4) ... Cathode lead wire, (5) ... Organic semiconductor,
(6) ... Silver paint conductive layer, (7) ... Solder layer, (8) ... Epoxy resin.

Claims (4)

[Claims] 1. A method for producing a solid electrolytic capacitor, wherein a capacitor element formed by forming an anodized film on a film-forming metal is impregnated with a molten and liquefied organic semiconductor, and cooled and solidified. A method for manufacturing a solid electrolytic capacitor, comprising: a step of impregnating pure water into the solidified capacitor element; and a step of drying water in the capacitor element. 2. The method for producing a solid electrolytic capacitor according to claim 1, wherein the organic semiconductor is a TCNQ salt of N- (alkyl) -quinolinium (or isoquinolinium). 3. The solid electrolytic capacitor according to claim 1 or 2, wherein the capacitor element is a winding element formed by winding an anode foil and a cathode foil with separator paper interposed therebetween. Manufacturing method. 4. The capacitor element is a capacitor element formed by pressure-molding or sintering a metal powder having a valve action such as aluminum, tantalum and niobium. Item 2. A method for producing a solid electrolytic capacitor as described in Item 2 or Item 2.