JPS62266818A - 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 Field of the Invention The present invention relates to a solid electrolytic capacitor with an improved method of forming a solid electrolyte.

BACKGROUND OF THE INVENTION A conventional method for forming a solid electrolyte involves immersing a valve metal electrode having an oxide film in a manganese nitrate solution and then subjecting it to a thermal decomposition treatment to deposit manganese dioxide on the electrode.

Problems to be Solved by the Invention However, when a manganese dioxide layer is formed on an electrode, it is generally immersed in a manganese nitrate solution and then thermally decomposed, so the anodic oxide film is damaged by the nitric acid.
It was necessary to carry out thermal decomposition and reformation ~7 times. Further, it was necessary to perform chemical conversion at a voltage three to four times higher than the rated voltage.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a solid electrolytic capacitor characterized in that a solid electrolyte layer is formed using an organic metal salt such as an alkoxide that has little chemical action on the oxide film. It is.

That is, an oxide film layer is formed on the surface of the valve metal electrode,
The solid electrolytic capacitor is characterized in that an organic metal salt such as an alkoxide is deposited on the oxide film layer and a solid electrolyte layer is formed by heat treatment.

A valve metal made of aluminum foil that has been chemically treated with a solution of organic metal salts such as alkoxides dissolved in xylene, etc.! It is coated on the surface of the wafer, dried, and then heat-treated to sinter it to thermally decompose the organic metal, forming a solid electrolyte layer with excellent heat resistance.

As for the coating method, the dipping and then pulling method was the most favorable.

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

M(OR), -1 → MO++/! ” R.O.
R here M: Metal element R: Alkyl group or other organic substance Metals that form alkoxides such as manganese, tin, etc., whose oxides exhibit semiconducting properties are coated on the aluminum oxide surface, and the thermal decomposition method is applied. A solid electrolyte with excellent heat resistance can be produced by precipitation with almost no damage to the oxide film.

Example As an electrode for the anode, an aluminum foil etched to a surface magnification of approximately 100 times was subjected to 14V chemical conversion, and after being slifted into a narrow width, electrolytic paper, cathode, and electrolytic paper were layered in this order, and lead leads were connected to both electrodes and wound. Then, a capacitor element was created.

13V was applied to both electrodes of this device in an electrolytic solution, and the device was aged for 15 minutes. After washing with pure water, the capacitor element was immersed in the organic metal salt solution shown in Table 1 and pulled out.
After drying at ℃ for 5 minutes, it was fired for 10 minutes in an atmosphere of 350 ℃. After repeating this immersion-drying-baking process three times, it was placed in a case, sealed with resin, and aged.

In addition, as a comparison sample, a chemical formation voltage of 1 was used as an anode electrode.
Capacitor elements of 4V and 60V were prepared in the same manner as described above, immersed in a manganese nitrate solution, and fired and reconstituted at 300°C. After repeating this firing-reforming process six times, it was placed in a case, sealed with resin, and aged. The product characteristics at that time are shown in Table 2.

The ratings of the capacitors are 1OV and 33 μF, and the characteristic values in Table 2 are the average values of 10 samples.

As shown in Table 1 and Table 2, the conventional method with a 14V formation voltage short-circuited, and the 60V formation voltage had a high leakage current, and the capacitance was lower than that of the present invention. In contrast, the product of the present invention has sufficient practicality and is thermally stable, making it possible to directly cover the capacitor element with resin by transfer molding. Useful for making aluminum electrolytic capacitors into chips.

In addition, although the above-mentioned embodiment described a wound type solid electrolytic capacitor using an etched aluminum foil as a valve metal electrode, the same effect can be obtained when the valve metal electrode is plate-shaped or an aluminum electrode such as a sintered body. . Furthermore, adding reconversion after firing the organic metal salt has the effect of further reducing leakage current.

Effects of the Invention As described above, the characteristics of the electrolytic capacitor of the present invention are greatly improved, and it can be easily mass-produced, and has great industrial and practical value.

Claims (2)

[Claims] (1) Forming an oxide film layer on the surface of the metal electrode, depositing an organic metal salt such as an alkoxide on the oxide film layer,
A solid electrolytic capacitor characterized by forming a solid electrolyte layer through heat treatment. (2) The solid electrolytic capacitor according to claim 1, wherein the alkoxide is an organic metal salt containing manganese or tin.