JPH0620876A - Manufacture of solid-state electrolytic capacitor - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] By immersing the anode electrode in a solution of TCNQ and a salt of a donor material, a TCNQ complex is produced and deposited on the anode electrode by an anodic electrolytic reaction to form the above complex. It can be impregnated even at a temperature close to the decomposition point, enhances the bondability between the electrode surface and the TCNQ complex, and makes it possible to reduce the tan δ of the solid electrolytic capacitor. [Structure] An anode electrode is immersed in a solution of TCNQ and a salt of a donor material, and a TCNQ complex is generated and deposited on the anode electrode by an anodic electrolytic reaction to impregnate it.

Description

Detailed Description of the Invention

[0001]

The present invention relates to TC as a solid electrolyte.
The present invention relates to a method for manufacturing a solid electrolytic capacitor using an NQ complex.

[0002]

2. Description of the Related Art In a conventional solid electrolytic capacitor in which a solid electrolyte is interposed between an anode body electrode made of a valve metal having an anodized film on its surface and a cathode electrode formed facing the electrode. Have used manganese dioxide as a solid electrolyte.

However, according to this method, when manganese dioxide is formed on the electrode, the anode electrode is generally immersed in a manganese nitrate solution and then thermally decomposed, so that the anodic oxide film is damaged. It has a drawback that the anodic oxide film formed by manganese dioxide is poor in film recoverability.

As a method of compensating for these drawbacks, solid electrolytic capacitors using an organic semiconductor such as TCNQ complex as a solid electrolyte have appeared. As a typical example of this impregnation method, as described in JP-A-57-173928, an organic semiconductor containing a TCNQ complex is liquefied by heating and melting, and an element is put in until decomposition and rapid solidification. It is what makes me.

However, according to this method, the TCNQ complex to be used has a melting point and a decomposition point, and impregnation property becomes extremely poor unless there is a certain temperature interval. TCN
The decomposition point of the Q complex is around 290 ° C., which is the sublimation temperature of TCNQ, and the melting temperature must be lowered in order to have a temperature range between the melting point and the decomposition point.

On the other hand, solid electrolytic capacitors are required to have heat resistance, and especially for chip products, the electrolyte must be able to withstand solder dip and reflow temperatures during surface mounting. Suitable for TCN
It is quite difficult for the Q complex to withstand the above heat resistance. That is, since the TCNQ complex having excellent heat resistance has a high melting point and a small temperature difference from the decomposition point, impregnation property is extremely deteriorated. On the other hand, if the impregnation property is improved, the melting point will be on the low temperature side, and the heat resistance will be extremely deteriorated.

[0007]

SUMMARY OF THE INVENTION The present invention is to solve the above problems. That is, the heat-resistant complex had a high melting point and a sufficient difference from the decomposition point to impregnate it. However, the present invention makes it possible, and the bonding property between the electrode surface and the TCNQ complex is strengthened and the tan δ of the capacitor is improved. Is intended.

[0008]

As a concrete means of the present invention, (1) a valve action metal or an alloy of the metal having a surface having an enlarged anode electrode and an anodic oxide film on the surface, and a solid In a method for manufacturing a solid electrolytic capacitor using a TCNQ complex as an electrolyte, the anode electrode is immersed in a solution of TCNQ and a donor salt, and a TCNQ complex is produced and deposited on the anode electrode by an anodic electrolysis reaction. A method for manufacturing a solid electrolytic capacitor, characterized in that the solid electrolytic capacitor is impregnated therewith. (2) The method for producing a solid electrolytic capacitor according to claim 1, wherein a supporting electrolyte is used. (3) The method for producing a solid electrolytic capacitor according to claim 1 or 2, wherein the valve action metal is aluminum or its alloy. The valve action metal used in the method of the present invention is a metal whose oxide serves as an electrical insulator (dielectric) and refers to Group 3, Group 4 and Group 5 metals of the periodic table, for example, A
1, Ti, Zr, Hf, Ta, Nb, etc., but Al is particularly preferably used because it is inexpensive in cost, the surface area can be easily expanded by electrolytic etching, and a high capacitance can be obtained. It The metal alloy is Al-Ti,
There are Al-Zr, Al-Hf, Al-Ta, Al-Nb, and the like, and a plurality of combination alloys of Al and Ti, Zr, Hf, Ta, and Nb. The donor material is a substance that gives a stable counter cation in the TCNQ complex, and an electron donating substance is used. Examples of suitable donor materials are quinoline, isoquinoline, indol, quinazoline, quinoxaline, carbazol, acridine, phenanthridine,
Phenazine or its derivative is an aromatic amine having a relatively high boiling point. The donor material salt is a salt of the donor material, and includes both a quaternary salt and a proton acid salt. The quaternary salt of the donor material is prepared, for example, by reacting the donor material with an alkyl halide. As the alkali halide, a straight-chain or branched-chain alkyl chloride, bromide or iodide having 1 to 16 carbon atoms, particularly 1 to 10 carbon atoms can be used, but is particularly suitable for impregnation with aluminum or an aluminum alloy. Iodide is preferable because the reaction proceeds efficiently. Further, as the counter ion of the quaternized salt of the donor material, a sulfate ion or a sulfonate ion may be used in addition to the halogen ion. Further, as the proton acid salt of the donor material, hydrochloride, hydrobromide, sulfate, sulfonate, phosphate,
Examples include nitrates.

The basic idea of the present invention is that liquid TCNQ is used.
By using the complex raw material to deposit a solid TCNQ complex on the anode electrode of the capacitor by the electrodeposition method, TC
The purpose is to efficiently impregnate the electrode with the NQ complex. 19
The remarkable development of organic electrochemistry since the latter half of the 1970s has greatly contributed to various fields, and the present invention was also found out from such a background. That is, in organic electrolysis, it has become possible to control the reaction of active reactive species by selecting the combination of electrolytic solution-supporting electrolyte-electrode. It was considered that the electrode formation reaction of the TCNQ complex was caused by the conjugation of the radical formation in the electrolytic oxidation of TCNQ and the organic synthesis reaction with the donor material. Therefore, the present inventor repeated various studies and found conditions under which the conductive complex can be formed on the electrode.

That is, as the anode electrode, for example, a valve action metal whose surface is enlarged by an etching treatment and a dielectric film of an oxide film is formed on the surface is used, and the behavior in the electron transfer process at the electrode is While paying attention, the conditions under which the TCNQ complex formation reaction occurs were searched. As a result, as described above, a good product can be obtained by immersing the anode electrode in a solution of TCNQ and a donor salt and depositing a TCNQ complex on the electrode by an anodic electrolytic reaction. It has been found. At this time, as the solvent, those in which TCNQ and the donor material salt are relatively soluble are preferable, and methylene chloride, acetonitrile and the like are particularly preferably used. In carrying out this reaction, it is desirable to use a supporting electrolyte, and a suitable supporting electrolyte may be paratoluene sulfonic acid.

[0011]

EXAMPLE 1 Specific examples of the present invention will be described below. High-purity aluminum foil with a thickness of 90 μm (purity 99.99%)
Electrolytic etching is performed by alternating current to prepare an electrode foil with a surface area that is about 80 times larger.
V formation was performed to form a dielectric film. (Electrode A)

[0012] The above electrode, normal octyl quinoline ⁺
The iodide and excess TCNQ and paratoluenesulfonic acid were dipped in a solution of methylene chloride to obtain a current of 5 m.
A constant current anodic reaction was carried out at A for 5 hours. Then, after being dried, colloidal carbon was applied and formed, and the cathode lead was taken out with a silver paste and was covered with an epoxy resin to prepare a 10V 33 μF solid electrolytic capacitor.
For comparison, the melting impregnation method that is currently used was also conducted to investigate the characteristics.

[0013]

Example 2 An Al90Zr10 alloy foil having a thickness of 40 μm was produced by a super-quenching method, and a 99.99% aluminum foil having a thickness of 70 μm was used as a core material to produce a three-layer clad electrode foil. After that, electrolytic etching is performed to obtain a CV product of about 4000 μFV / cm.
^The electrode foil having No. ² was used, and a 20 V chemical conversion was performed with a neutral phosphoric acid solution to form a dielectric film. (Electrode B)

The above electrode was immersed in a solution of N-methyl 1,10 orthophenanthroline ⁺ iodide, excess TCNQ and paratoluenesulfonic acid dissolved in methylene chloride, and a constant current anodic reaction was performed at a current of 10 mA for 5 hours. Was done. Next, it is dried and coated with colloidal carbon, and then silver paste is used to colloidal carbon.
Carbon was applied and formed, and then the cathode lead was taken out with a silver paste, and was packaged with an epoxy resin to prepare a 10V 100 μF solid electrolytic capacitor. For comparison, the melting impregnation method that is currently used was also conducted to investigate the characteristics.

The results of Example 1 are shown in Table 1, and the results of Example 2 are shown in Table 2.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

As shown in Tables 1 and 2, in addition to the improvement of tan δ, the products treated according to the present invention have an improved impregnation property as seen in the increase of capacitance. Also, it shows good characteristics as compared with the conventional melt impregnation method.
Further, it is possible to impregnate a TCNQ complex having no melting point, which is impossible with the conventional melt impregnation method, which is of great industrial and practical value.

Claims (3)

[Claims] 1. A method for producing a solid electrolytic capacitor comprising a valve-action metal or an alloy of the metal having an anodized film on an enlarged surface of the anode electrode and an anodized film on the surface and using a TCNQ complex as a solid electrolyte, wherein TCNQ and A method for producing a solid electrolytic capacitor, characterized in that the anode electrode is immersed in a solution with a donor material salt, and the TCNQ complex is generated and precipitated on the anode electrode by an anodic electrolysis reaction to impregnate the electrode with the TCNQ complex. 2. The method for producing a solid electrolytic capacitor according to claim 1, wherein a supporting electrolyte is used. 3. The method for producing a solid electrolytic capacitor according to claim 1, wherein the valve action metal is aluminum or its alloy.