JPH0719728B2 - Method for manufacturing solid electrolytic capacitor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid electrolytic capacitor, which is an improved method for forming solid valve disintegration.

2. Description of the Related Art Conventionally, as a method for forming a solid electrolyte, a valve metal electrode having an oxide film was immersed in a manganese nitrate solution, and then subjected to a thermal decomposition treatment to deposit manganese dioxide on the electrode.

Problems to be Solved by the Invention However, when the manganese dioxide layer is formed on the electrode, it is generally immersed in a manganese nitrate solution and then thermally decomposed.
It was necessary to pyrolyze and re-form 7 times. In addition, it was necessary to perform chemical formation at a voltage 3 to 4 times the rated voltage.

Means for Solving the Problems The present invention is a method for manufacturing a solid electrolytic capacitor, which comprises forming a solid electrolyte layer using an alkoxide having a small chemical action on an oxide film in order to solve the above problems. .

That is, an oxide film layer is formed on the surface of the valve metal electrode,
The method for producing a solid electrolytic capacitor is characterized in that an alkoxide is attached onto the oxide film and heat treatment is performed to form a solid electrolyte layer.

Action A solution of alkoxide dissolved in xylene is applied on the surface of a valve metal electrode made of aluminum foil that has been subjected to chemical conversion treatment, dried and then heat-treated to thermally decompose the organic metal, resulting in excellent heat resistance. A solid electrolyte layer can be formed.

As the coating method, the method of pulling up after dipping was the best.

The general formula of the thermal decomposition reaction of the alkoxide during firing is shown by the following formula.

Here, M: metal element R: alkyl group or other organic substance, a metal such as alkoxide, for example, manganese,
To produce a solid electrolyte with excellent heat resistance without causing damage to the oxide film by applying tin or other oxide whose semiconductor properties are shown on the aluminum oxide surface and depositing it by a thermal decomposition method. You can

Example As an anode electrode, 14V chemical formation was performed on an aluminum foil that had been etched to a surface magnification of about 100 times, and after slitting narrowly, the electrode paper, cathode, and electrolytic paper were stacked in this order and connected to both electrodes with lead wires and wound. , A capacitor element was created.

This device was applied with 13 V to both electrodes in an electrolytic solution, and the device was aged for 15 minutes. After washing with pure water, immerse the capacitor element in the organic metal salt solution shown in Table 1 and pull it up.
After drying for 1 minute, it was baked in an atmosphere of 350 ° C. for 10 minutes. After repeating this dipping-drying-firing three times, it was housed in a case, resin-encapsulated, and aged.

As a comparative sample, the formation voltage of 14
Capacitor elements of V type and 60 V type were prepared in the same manner as described above, immersed in a manganese nitrate solution, and calcined at 300 ° C.-reformation was performed. After repeating this firing-reformation 6 times, the product was housed in a case, resin-encapsulated, and aged. The product characteristics at that time are shown in Table 2.

The ratings of the capacitors are 10V and 33μF, and Table 2 and the characteristic values show the average values of 10 samples.

As shown in Table 2, all of the conventional methods with 14V formation voltage are short-circuited, and those with 60V formation voltage have high leakage current, and the capacitance is about 20% of that of the present invention. On the other hand, since the product of the present invention has sufficient practicality and is thermally stable, it is possible to directly resin-encapsulate the above-mentioned capacitor element by the transfer molding method, and form an aluminum electrolytic capacitor into a chip. Useful for.

In addition, although the above-mentioned embodiment has described the winding type solid electrolytic capacitor using the etched aluminum foil as the valve metal electrode, the valve metal electrode has a similar effect even when it is a plate-shaped or sintered aluminum electrode. . Further, if re-formation is added after firing the alkoxide, it has an effect of further reducing the leakage current.

EFFECTS OF THE INVENTION As described above, the characteristics of the electrolytic capacitor according to the method of the present invention are greatly improved and can be easily mass-produced, which is of great industrial and practical value.

Claims (2)

[Claims] 1. A solid electrolytic capacitor comprising an oxide film layer formed on a surface of a valve metal electrode, an alkoxide attached to the oxide film layer, and a heat treatment to form a solid electrolyte layer. Method. 2. The method for producing a solid electrolytic capacitor according to claim 1, wherein the alkoxide is an alkoxide containing manganese or tin.