JP2783932B2 - Manufacturing method of organic semiconductor solid electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an organic semiconductor solid electrolytic capacitor.

[0002]

2. Description of the Related Art It is already known that an organic semiconductor comprising a complex salt of TCNQ 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, an anode foil and a cathode foil are wound with a separator paper interposed therebetween, and the separator paper is It has also been proposed to impregnate the above solid electrolyte (Japanese Patent Publication No. Sho 6
2-52939, H01G 9/02). In addition, TCNQ
Means 7.7.8.8-tetracyanoquinodimethane.

[0003] In the latter prior art, after forming an etched aluminum foil for an anode and an aluminum foil for a cathode through a separator paper, forming a cut portion and a lead caulking portion of the chemically etched aluminum foil. For the purpose of repairing the defective portion of the chemical conversion film, which is a dielectric, a re-chemical conversion treatment is performed in the state of the capacitor element. This re-chemical treatment improves the leakage current characteristics of the completed capacitor.

[0004] Next, an appropriate amount of organic semiconductor powder composed of a TCNQ complex salt is moderately pressurized, stored in an aluminum capacitor case having good thermal conductivity, and heated to about 250 to 350 ° C to melt the organic semiconductor powder. The capacitor element that has been liquefied and preheated in advance is put into a case and impregnated with the melted and liquefied organic semiconductor.

After the capacitor element is impregnated with the melted and liquefied organic semiconductor, it is immediately quenched and solidified. After that, the case opening is sealed with epoxy resin to complete the product.

[0006]

By the way, an oxide film as a dielectric is formed on the anode of the capacitor element. However, heat shock during preheating of the element and impregnation of the molten and liquefied organic semiconductor, or Due to mechanical shock during the sealing of the epoxy resin and the transportation of the capacitor element, the oxide film, which is the dielectric layer, was extremely fine but cracked, deteriorating the leakage current characteristics after the finished product. .

[0007] Therefore, after impregnating with an organic semiconductor or sealing with a resin, a voltage treatment, that is, an aging treatment is performed at a temperature of about 100 ° C for the purpose of repairing an oxide film and reducing a leakage current value. However, compared to the aluminum electrolytic capacitor using a general electrolytic solution, the solid electrolyte TCN
The Q complex salt has a drawback that the oxide film has poor repairability, and has a problem that the above-described leakage current value is large and the yield is low. The present invention improves the repair performance of the leakage current of the organic semiconductor and improves the leakage current characteristics.

[0008]

According to the present invention, there is provided an organic semiconductor solid electrolytic capacitor comprising a capacitor element formed by forming an anodic oxide film on a film-forming metal, impregnated with a molten organic semiconductor, and cooled and solidified. In a method of manufacturing a capacitor, an organic semiconductor is heat-treated at a temperature equal to or lower than its melting point before melting and liquefaction.

[0009]

According to the present invention, before the organic semiconductor is melted and liquefied, the organic semiconductor is heat-treated at a temperature equal to or lower than the melting temperature, thereby improving the repairability of the oxide film during the aging treatment and improving the leakage current value. Can be reduced. Although the mechanism of the above action is not clear, the following may be considered. Aging concentrates current due to aging in the part of the dielectric layer, which is extremely fine but weakened due to flaws (cracks), and the Joule heat insulates the organic semiconductor to repair the leakage current. it is conceivable that. At that time, it is considered that the organic semiconductor that has been subjected to the heat treatment according to the present invention is more likely to be insulated by aging than the one that has not been subjected to the heat treatment.

[0010]

【Example】

First Embodiment Manila paper having a thickness of 50 μm is interposed as a separator paper between an aluminum foil for an anode and an aluminum foil for a cathode which has been subjected to an etching treatment and a chemical conversion treatment, and this is wound up into a cylindrical shape to form a capacitor element. I do.

Thereafter, a chemical conversion treatment is carried out together with the capacitor element for the purpose of repairing the cut portion of the anode foil, the lead caulking portion, and the defective portion of the aluminum oxide film as the dielectric layer, using a chemical conversion solution composed of ammonium adipate or the like. .

Next, a TCNQ complex salt (N-n) as an organic semiconductor is placed in a bottomed cylindrical aluminum capacitor case.
-Butylisoquinolinium (TCNQ ₂ ) powder is packed under moderate pressure, and for each temperature of 150 ° C., 160 ° C. and 170 ° C. which is lower than the melting temperature of the TCNQ complex salt, 1 hour,
The heat treatment is performed for the entire aluminum case with different heating times of 2 hours, 3 hours, 4 hours, and 5 hours. In this embodiment, the temperature
(3 ways) × time (5 ways) = 15 conditions in total.

Next, the heat-treated TCNQ complex salt was added to 28
The mixture is melted and liquefied at a temperature of 0 to 300 ° C., and the capacitor element is immersed to impregnate the liquefied TCNQ complex salt. After the impregnation, the entire case is rapidly cooled to cool and solidify the TCNQ complex salt impregnated in the capacitor element. By such a step, the capacitor element is impregnated with the liquid TCNQ complex salt,
The NQ complex recrystallizes and exhibits high conductivity.

Further, after closing the opening of the case with epoxy resin, a specified DC voltage of the capacitor is finally applied at about 125 ° C. for 1 hour, that is, aging treatment is performed to obtain the desired organic semiconductor solid electrolytic capacitor. Complete. Incidentally, the rating of the capacitor element used in this embodiment is 20 V, 33
The specified aging voltage was 20 V in μF.

Table 1 below shows the conditions of the present embodiment in a matrix, and each condition is represented by an alphabet.

[0016]

[Table 1]

Table 2 below reports the results of this test. For the leakage current, a pass / fail judgment is made at 0.02 CV (13.2 μA), and only the non-defective products have an average value of 30 samples in the LC column. (C: capacitance, V: rated voltage) For LC yield, the percentage of non-defective products selected based on the above-mentioned pass / fail judgment criteria is described. In the conventional example, heat treatment prior to melting and liquefaction of the TCNQ complex salt is not performed.

[0018]

[Table 2]

. [0019] Cap (capacitance), tan [delta: 120H _Z (room temperature), ESR (equivalent series resistance): 100KH _Z (room temperature) LC (leakage current): DC 20 V is applied, measured at 30 seconds value (room temperature).

Second Embodiment A capacitor element similar to that of the first embodiment was used. The organic semiconductor is Nn-amylisoquinolinium T
A CNQ _2, the powder was suitable amount contained in an aluminum condenser case, a heat treatment is performed 170 ° C. × 1 hour and 170 ° C. × 2 hours. The following trial production conditions are exactly the same as in the first embodiment. Report a test result using the N-n-amyl isoquinolinium TCNQ ₂ in Table 3 below.

[0021]

[Table 3]

[0022] Cap, tan [delta:. 120H _Z (room temperature) ESR: 100KH _Z (room temperature) LC: D.C.20V applied, measured at 30 seconds value (room temperature).

As described above, the present invention is not limited to the case where a winding element formed by winding an anode foil and a cathode foil with a separator paper interposed therebetween is used as the capacitor element. The present invention is also applied to a sintered element in which a metal powder having a valve action, such as aluminum, is pressed and fired and used as a capacitor element.

Next, an embodiment of the present invention in a sintered element will be described. A capacitor element formed by implanting and sintering an aluminum lead wire for an anode on aluminum fine powder having a particle size of 10 to 40 μm is electrochemically formed with an oxide film layer serving as a dielectric using a chemical conversion solution.

As the solid electrolyte in the capacitor element,
A TCNQ complex salt is used in the same manner as in the above embodiment. The TCNQ complex salt is melted at a temperature of 280 to 300 ° C. in the case, and the capacitor element is immersed in the case to impregnate the TCNQ complex salt. After the impregnation, remove the capacitor element from the case,
The mixture is quenched with air to solidify the TCNQ complex salt. By such a process, the liquid TCNQ complex salt is impregnated inside the capacitor, and the TCNQ complex salt is recrystallized by rapid cooling to form a solid electrolyte having high conductivity.

In a subsequent step, as shown in FIG. 1, a copper paint conductive layer (6) and a solder layer (7) are formed, and a cathode lead (4) is formed.
And the anode lead wire (3) is welded to the aluminum lead (2) planted on the capacitor element (1). Finally, an outer layer is formed with an epoxy resin (8), and 125
Apply the rated voltage of the capacitor at about ° C for about 1 hour to complete the target capacitor. Reference numeral (5) denotes an organic semiconductor.

[0027]

As is apparent from the results of the first and second embodiments, the present invention improves the leakage current characteristics,
The yield can be greatly improved. In addition, if the heat treatment conditions of the organic semiconductor become severe (temperature: high, time: long), L
C yield is improved, but other electrical characteristics (tanδ, ES
R) tends to worsen. Therefore, the heat treatment conditions for the TCNQ complex salt are the same as those described in this example (15
(0.about.170.degree. C..times.1 to 5 hours) can be said to be a desirable condition. However, if the heat treatment is performed at a temperature of 100.degree. It should be noted that the present invention is not limited to the configuration of the above embodiment, and various modifications can be made within the scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols]

 (1) Capacitor element

Claims (3)

(57) [Claims] 1. A method for producing a solid electrolytic capacitor in which a capacitor element formed by forming an anodic oxide film on a film-forming metal is impregnated with a melted and liquefied organic semiconductor and cooled and solidified.
A method for producing an organic semiconductor solid electrolytic capacitor, wherein an organic semiconductor is heat-treated at a temperature of 100 ° C. or more and a melting point or less before melting and liquefaction. 2. The method for producing an organic semiconductor solid electrolytic capacitor according to claim 1, wherein an oxide film is formed on the surface of a metal sintered body having a valve action, such as tantalum, niobium, or aluminum, as a capacitor element. 3. The organic semiconductor is a complex salt of 7.7.8.8-tetracyanoquinodimethane (TCNQ).
Alternatively, the method for producing an organic semiconductor solid electrolytic capacitor according to claim 2.