Nippon Light Metal Company, Ltd.

Yuya Yoshida

Masahiko Katano

Toshifumi Taira

Yuta Shimizu

Shinya Sone

Masashi Mehata

Yoshihiro Taguchi

Masashi Isobe

Asami Shirai

Provided is a method for producing an electrode for an electrolytic capacitor, the method comprising: a hydration step in which an aluminum electrode is immersed in a hydration treatment solution having a temperature of 80&#xb0; C. or higher; and a chemical conversion step in which the aluminum electrode is subjected to chemical conversion treatment up to a formation voltage of at least 400 V. The hydration treatment solution contains a hydration inhibitor. The thickness of a hydrated film formed in the hydration step satisfies the following condition, 0.6&#x2264;t2/t1&#x2264;1, wherein t1 is the average thickness of the hydrated film formed in a depth range of up to 100 &#x3bc;m from the surface of the aluminum electrode, and t2 is the average thickness s of the hydrated film formed in a deep portion at least 100 &#x3bc;m from the surface of the aluminum electrode.

Method for producing electrode for aluminum electrolytic capacitor

An aluminum electrode in which a porous layer made of a sintered layer of aluminum powder having an average particle diameter of 1 &#x3bc;m to 10 &#x3bc;m is laminated in a thickness of 150 &#x3bc;m to 3000 &#x3bc;m on a surface of an aluminum core material is produced by chemical formation to produce an anode for an electrolytic capacitor. In this process, an organic acid immersion step of immersing the aluminum electrode in an organic acid aqueous solution containing dodecanoic acid, benzoic acid, propanedioic acid, butanedioic acid, (E)-2-butenedioic acid, 2-hydroxypropane-1,2,3-tricarboxylic acid, (E)-1-propene-1,2,3-tricarboxylic acid, or the like is carried out after a pure water boiling step and before a chemical formation step. In the chemical formation step, a phosphoric acid immersion step of immersing the aluminum electrode in an aqueous solution containing phosphate ions is carried out one or more times in the course of raising a film withstand voltage to a chemical formation voltage.

A porous aluminum electrode has a porous layer formed by sintering aluminum powder on the surface of an aluminum core. The porous aluminum electrode, when subjected to a formation to a voltage of 200V or more, is boiled and then subjected to a first forming process in which formation is performed in an aqueous solution of ammonium adipate at a temperature of 80&#xb0; C. or below and a second forming process in which formation is performed in a boric acid aqueous solution. When heat depolarization is first carried out, washing with water is performed for five minutes or more before heat depolarization; therefore, the porous layer is not destroyed.

Method for manufacturing electrode for aluminum electrolytic capacitor

This invention provides an aluminum electrode plate for an electrolytic capacitor, which, even when the thickness of an etching layer is large, can realize a high level of impregnation of a solid electrolyte and can reduce ESR of a capacitor. An aluminum plate having an aluminum purity of not less than 99.98% by mass is etched to form an etching layer having a depth of 70 &#x3bc;m or above. When a plane cross section of a position deeper than 20 &#x3bc;m from the surface in the etching layer is measured with an image analyzer, for each measured face, not less than 70% of the total number of pits within the measured face is accounted for by pits having a diameter of 0.01 to 1 &#x3bc;m &#x3c6;; in terms of equivalent circle diameter. The aluminum plate has an aluminum purity of not less than 99.98% by mass and comprises 5 to 50 ppm of Fe and 5 to 40 ppm of Cu with the balance consisting of inevitable impurities. The aluminum plate further contains 1&#xd7;10to 10/cmiron-containing intermetallic compound having a particle diameter of 0.1 to 1.0 &#x3bc;m &#x3c6; in terms of spheres.

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Shizuoka, Japan

Yuya Yoshida