JPH0373509A - Manufacturing method of solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a solid electrolytic capacitor using a conductive polymer film as a solid electrolyte.

(Prior Art) In recent years, solid electrolytic capacitors that meet the demand for smaller size and higher performance have been disclosed in Japanese Patent Publication No. r!a01160-244017 or Japanese Patent Application Laid-open No. 181308/1983.

The techniques disclosed in these publications involve chemically converting a valve metal with a roughened surface, forming an oxide film, and using the unipolar body as an anode, immersing it in an electrolytic solution and energizing it. An electrolytic polymer film formed in a film amount is used as a solid electrolyte, but since the oxide film is an insulator, II! Effective current conduction with the electrodes was not carried out, and current was concentrated in defective parts of the oxide film or in areas close to the cathode, making it extremely difficult to obtain a uniform electrolytic polymer film as a solid electrolyte.

Therefore, a chemical polymerization film is formed on the anode body in advance by immersing the anode body in a solution of virol, thiophene, or furan, and then immersing it in oxidizing agent II. Electrolytic oxidation polymerization is carried out in an electrolytic solution containing monomers such as virol, thiophene, and furan and a supporting electrolyte using the polymeric membrane as an anode, thereby effectively forming an electrolytic polymeric membrane on the chemically polymerized membrane.

Therefore, in order to remove the electrolytic solution remaining on the electrolytic polymerized membrane formed by such a method, a cleaning and drying process is required as a post-treatment.

Conventionally, washing with water has been used as a cleaning means, but the permeability of water to electrolytic polymer membranes such as polyvinyl, polythiophene, and polyfuran is extremely poor, and the rinsing with water as a monomer constituting the electrolyte is extremely difficult. , thiophene, furan, etc., have poor solubility in water and require long immersion cleaning.

However, due to the washing process using water, the following problems have arisen.

In other words, a certain amount of water permeates into the electrolytic polymerized membrane during the long-time washing process, but at the same time, remarkable 1 fira occurs in the electrolytic polymerized membrane and the chemically polymerized membrane, and in the subsequent drying process, these polymeric membranes are severely damaged. Due to the shrinkage, cracks occur in these polymer films and the oxide film that adheres to these polymer films, and t
The and[delta] characteristics deteriorated, and the graphite and silver paste were immersed in the cracks during the subsequent formation of the graphite and silver paste layers, causing deterioration of the leakage current characteristics and occurrence of short circuits.

In addition, insufficient cleaning is inevitable, and virol, thiophene,
It is difficult to completely remove furan and the like, and the remaining monomers and supporting electrolyte constituting the electrolytic solution cause deterioration in life characteristics.

(Problems to be Solved by the Invention) As described above, solid electrolytic capacitors that use a conductive polymer film as a solid electrolyte are attracting attention as they meet the demand for smaller size and higher performance. There were problems to be solved in the treatment method, especially the cleaning method.

The present invention has been made in view of the above points, and has an excellent t
The object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor that improves an δ, Il leakage current, life characteristics, and cleaning means after forming an electrolytic polymer film, which is a condition for reducing short-circuit defects.

[Structure of the invention]

(Means for Solving Problem H) The method for manufacturing a solid electrolytic capacitor of the present invention involves forming a chemically polymerized film made of a conductive polymer by chemical oxidative polymerization on an oxide film formed on a valve metal. A method for manufacturing a solid electrolytic capacitor in which an electrolytic polymeric film made of a conductive polymer is formed on a chemically polymeric film by electrolytic oxidative polymerization, and then the electrolytic oxidative polymer solution remaining on the electrolytic polymeric film is washed. This method is characterized by being carried out using a polar organic solvent.

(Function) According to the above configuration, the permeability of the polar organic solvent to the electrolytically polymerized membrane is good, and since the electrolytically oxidized polymer solution has a high solubility in the polar organic solvent, it remains in the electrolytically polymerized membrane in a short time. Electrolytic oxidation polymerization solution can be completely removed.

In addition, polar organic solvents have an extremely small swelling effect on the polymer film, and because the cleaning process is short, there is almost no shrinkage of the polymer film in the subsequent drying process, and the cause of cracks in the polymer film and oxide film is dissolved. Ru.

(Example> An embodiment of the present invention will be described below.

That is, as shown in FIG. 1, an anode lead wire 3 is attached to an anode foil 2 made of, for example, high-purity aluminum, whose surface area has been expanded by etching and an oxide film 1 has been formed on the surface through a chemical conversion process. After this N pole 2 is immersed in an aqueous solution of virol, thiophene, or furan/ethanol, it is further immersed in an aqueous ammonium persulfate solution to perform chemical oxidation polymerization to form a chemically polymerized WA4 made of conductive polymer on the oxide film 1. do.

The capacitor element wrapped around the anode 2 with the chemical polymerization 114 formed thereon is re-formed to repair the oxide film, and then the capacitor element is coated with the supporting electrolyte, virol, and thiophene.

It is immersed in an electrolytic oxidative polymerization solution containing a monomer such as furan, and subjected to electrolytic oxidative polymerization, thereby producing an electrolytic polymer II5 made of a conductive polymer on the chemically polymerized film 4.

Next, the capacitor element that has produced this electrolytic polymerization m5 is heated in acetone, acetonitrile, methanol, ethanol, etc. at 20°C with a dielectric constant of 20 or more (dipole efficiency 1.5).
(above)) is immersed in a polar organic solvent with infinite compatibility with water for 5 seconds to 30 minutes to remove the electrolytically oxidized polymer solution adhering to the electrolytically polymerized m5, and then used as a cleaning agent in the drying process. Remove the polar organic solvent.

Note that the immersion time in the polar organic solvent is appropriately set depending on the size of the capacitor element.

Next, this capacitor element is immersed in colloidal carbon and coated with silver paste to form a cathode layer 6, a cathode lead (not shown) is attached to this 11m electrode layer 6, and finally an exterior is applied. It is something.

According to the manufacturing method of a solid electrolytic capacitor having the above structure, since a polar organic solvent is used as a cleaning agent in the cleaning means performed after electrolytic oxidation polymerization, the permeability to the electrolytic polymer membrane is good, and the solubility of the electrolytic oxidative polymerization liquid is high. is large, so
The electrolytically oxidized polymer solution remaining on the electrolytically polymerized membrane can be removed in a short time, and furthermore, since the swelling of the polymerized membrane against polar organic solvents is extremely small, there is almost no shrinkage of the polymerized membrane in the subsequent drying process, and the polymerized membrane and oxidation This eliminates the occurrence of cracks in the film, and greatly contributes to improvements in tan δ, leakage current characteristics, short-circuit defects, and life characteristics.

Next, a solid electrolytic capacitor obtained by the present invention,
A comparison of the characteristics of solid electrolytic capacitors obtained using conventional examples will be described.

The robe is rated 1 according to Example A and the conventional example day described below.
This shows a comparison of the characteristics of 0V-3μF solid electrolytic capacitors, and Figures 2 to 4 show the life characteristics versus time at 105°C.

In addition, the values in the table excluding short-circuit defects are for sample 1.
The average value is 0.00, and the numbers in parentheses indicate variations.

Example A (1) Chemical oxidative polymerization conditions After immersing a chemically treated aluminum anode foil in a virol/ethanol solution for 5 minutes, 0.1 mol/j ammonium persulfate containing 0.05 ml/j tetraethylammonium toluenesulfonate as a supporting electrolyte. Immerse in aqueous solution for 5 minutes.

(2) Capacitor element structure and winding shape (3) Electrolytic oxidation polymerization conditions As pyrrole monomer 1 m01/j and supporting electrolyte,
It is immersed in 'HIM solution consisting of acetonitrile containing 1 mol/j of sodium para-toluenesulfonate, and constant current oxidative polymerization (1 mA/d, 30 minutes) is performed.

(4) Cleaning conditions after electrolytic oxidation polymerization Soak in acetone for 5 minutes.

4th day of bastion (1) Chemical oxidative polymerization conditions Same as Example A (2) Capacitor element structure Same as Example A (3) Electrolytic oxidative polymerization conditions Same as Example A (4) l! M [Cleaning conditions after chemical polymerization Soak in water for 10 minutes.

Table 1 As is clear from the above table, the tan δ and leakage of Example A are 1! compared to Conventional Example B. The flow characteristics are significantly improved, and short-circuit defects are significantly improved.

Moreover, as is clear from FIGS. 2 to 4, it can be seen that it contributes to the improvement of the nightcap change rate and the life characteristics of tan δ, and at the same time contributes to a significant improvement of the leakage current in the life characteristics.

In the above embodiments, an example in which an aluminum strip was used as the anode strip was explained, but it can be applied to a valve-acting metal foil such as tantalum or niobium foil. Sinter the powder consisting of
Of course, it can be applied to a sintered body.

[Effects of the Invention] According to the present invention, it is possible to easily remove the electrolytically oxidized polymerization solution adhering to the electrolytically polymerized membrane, and there is no swelling or shrinkage of the polymerized membrane, which greatly improves the initial properties (contributing to rF48I). , it is possible to obtain a method for manufacturing a solid electrolytic capacitor that can contribute to improving life characteristics.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway schematic sectional view showing the configuration of a capacitor element in the process of manufacturing according to an embodiment of the present invention, FIG. 2 is a time-capacitance change rate characteristic curve, and FIG. 3 is a time-tan δ characteristic curve I.
Figure I and Figure 4 are time-leakage current characteristic dbIIa diagrams. 1...Oxidation stage 112...Anode foil 4...Chemical polymerized membrane 5...Electrolytic polymerized membrane Patent application Person Marcon Electronics Co., Ltd. Nippon Carlit Co., Ltd. Figure 3 Time (h) Figure 4 Time (h) Figure 2

Claims (2)

[Claims] (1) After forming a chemical polymer film made of a conductive polymer by chemical oxidative polymerization on the oxide film formed on the valve metal, an electrolytic polymer film made of a conductive polymer is formed on this chemical polymer film by electrolytic oxidative polymerization. 1. A method for manufacturing a solid electrolytic capacitor in which the electrolytically oxidized polymer solution remaining on the electrolytically polymerized film is washed using a polar organic solvent. (2) The method for manufacturing a solid electrolytic capacitor according to claim (1), wherein the polar organic solvent is methanol, ethanol, acetone, or acetonitrile.