JP2007299820A - Method of manufacturing etching foil for electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an etching foil for an electrolytic capacitor by which capacity can be made larger by optimizing generation and growth of etching pits. <P>SOLUTION: The method of manufacturing an etching foil for an electrolytic capacitor is used to chemically and/or electrochamically etch an aluminum foil in an etching liquid containing at least chlorine ion. In this case, the etching liquid is added with an silicone oil, and furthermore it is blended with at least one kind of phosphate ions, nitrate ions, sulfate ions, and oxalate ions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an electrolytic capacitor etching foil.

  Aluminum foil for electrolytic capacitors is generally roughened and surface area increased by chemically or / and electrochemically etching aluminum foil in an etching solution containing chlorine ions for both anode and cathode. (For example, refer nonpatent literature 1).

The etching solution may further contain phosphate ions, nitrate ions, sulfate ions, oxalic acid and the like.
Isada Nagata, “Electrolyte Cathode Aluminum Electrolytic Capacitor”, Nihon Densetsu Kogyo Kogyo Co., Ltd., February 24, 1997, 2nd edition, 1st edition, pages 221-257

  In recent years, the demand for miniaturization of electrolytic capacitors has been increasing, and accordingly, the electrode foil used for electrolytic capacitors is required to have a higher capacitance than before, and the surface area of aluminum foil can be expanded more efficiently. Is desired.

  However, in the conventional etching method, hydrogen gas is generated when aluminum is dissolved in the etching solution, but a large amount of the generated hydrogen gas adheres to the aluminum surface, and an obstacle to the efficient generation and growth of etching pits. It has become.

  In view of the above problems, an object of the present invention is to provide a method for manufacturing an etching foil for an electrolytic capacitor capable of increasing the capacitance by optimizing the generation and growth of etching pits. is there.

  In order to solve the above problems, in the present invention, in the method for producing an electrolytic capacitor etching foil in which an aluminum foil is chemically or / and electrochemically etched in an etching solution containing at least chlorine ions, A method for producing an etching foil for an electrolytic capacitor, characterized by adding silicone oil.

  In this invention, the said etching liquid is a manufacturing method of the etching foil for electrolytic capacitors characterized by mix | blending at least 1 sort (s) among the phosphate ion, nitrate ion, sulfate ion, and oxalate ion further.

In the present invention, by adding silicone oil to the etching solution, the generation and growth of etching pits can be further optimized, and the capacitance per unit area can be increased.
The reason for this is that in the etching solution, silicone oil suppresses the generation of hydrogen gas and the adhesion of hydrogen gas on the surface of the aluminum foil. As a result, the generation of etching pits is not localized, and the etching pits are on the surface of the aluminum foil. It is thought that it occurs uniformly and grows as a whole.

The present invention can also be applied to the case where at least one of phosphate ions, nitrate ions, sulfate ions, and oxalate ions is added to the etching solution. Such ions have a film-forming ability with respect to aluminum, and when such ions are mixed in an etching solution, both dissolution of aluminum and film formation occur, and the generation and growth of etching pits are further optimized. Can do.
When silicone oil is added to such an etching solution, the effect becomes greater. The reason for this is that when silicone oil is added to the etching solution, both dissolution of aluminum and film formation occur efficiently, so that the generation and growth of etching pits can be further optimized.

Hereinafter, based on the Example of this invention, this invention is demonstrated in detail.
In Examples and Comparative Examples described below, Examples 1 to 8 were used using an etching solution containing 10.0 wt% hydrochloric acid, 2.0 wt% phosphoric acid, 2.0 wt% nitric acid, and 1.0 wt% sulfuric acid as a base. Then, a silicone oil having a concentration (% by weight) shown in Table 1 was added to the etching solution.
Here, the aluminum foil is an anode foil for low voltage having a purity of 99.9%.
Etching conditions were such that the electrolyte temperature was 30 ° C., the voltage waveform was a sine wave, the frequency was 60 Hz, and the current density was 0.4 A / cm ² .
Under any conditions, after the aluminum foil was etched, chemical cleaning was performed by a known method using an alkali and an acid.
The obtained etching foil was anodized under the condition of an applied voltage of 20 V in ammonium adipate. The results of measuring the capacitance value are shown in Table 1.

(Examples 1-8)
Addition of 0.0001 wt%, 0.0005 wt%, 0.001 wt%, 0.005 wt%, 0.01 wt%, 0.05 wt%, 0.1 wt%, and 0.5 wt% of silicone oil in the etching solution, respectively Etching solution was used.

(Comparative example)
An etchant in which silicone oil was not added was used in the etchant.

(result)
As can be seen from Table 1, the addition of silicone oil effectively generated and grown etching pits, and the formation capacity could be improved. Here, it can be seen that the addition amount of the silicone oil is effective even when 0.0001 wt% is added, and the capacitance is higher as the addition amount of the silicone oil is increased to 0.01 wt%. In addition, the capacitance does not change at 0.01 to 0.5 wt%, but when the amount exceeds 0.5 wt%, the contamination of the cleaning liquid increases, so the amount of silicone oil added is 0.01 to 0.5 wt%. % Range is preferred.
If the amount is less than 0.0005 wt%, the capacitance value decreases, and if it exceeds 0.5 wt%, the rate of increase in the formation capacity tends to decrease. Therefore, the amount of silicone oil added is more preferably in the range of 0.01 to 0.5 wt%.

  In the above embodiment, the etching solution is composed of 10.0 wt% hydrochloric acid, 2.0 wt% phosphoric acid, 2.0 wt% nitric acid, and 1.0 wt% sulfuric acid. However, the present invention is not limited to this. .

  Furthermore, in the above embodiment, the anode foil for low voltage is targeted, but even when the anode foil for cathode or medium / high voltage is used, the capacitance can be increased by adding silicone oil. it can.

Claims (2)

In a method for producing an etching foil for an electrolytic capacitor, in which an aluminum foil is chemically or / and electrochemically etched in an etching solution containing at least chlorine ions,
A method for producing an etching foil for an electrolytic capacitor, comprising adding silicone oil to the etching solution.   2. The method for producing an etching foil for an electrolytic capacitor according to claim 1, wherein the etching liquid further contains at least one of phosphate ions, nitrate ions, sulfate ions, and oxalate ions. 3.