KR100732705B1 - Etching method of cathode foil for aluminum electrolytic capacitor - Google Patents

Abstract

The present invention relates to a method for improving the etching efficiency of an anode foil for an aluminum electrolytic capacitor, and more particularly, in an electrolyte solution containing hydrochloric acid as a main component when applying an alternating current in an electrolyte solution containing chlorine ions to an aluminum foil. The present invention provides a method for producing a cathode foil for an aluminum electrolytic capacitor, by adding sulfuric acid of 0.1 to 0.5N and performing electrolytic etching according to current density, temperature, and frequency, thereby increasing the surface area of the aluminum foil and increasing capacitance.

Aluminum Electrolytic Capacitors, Alternating Current, Etching, Cathode Foil, Hydrochloric Acid, Surface Area, Capacitance

Description

Etching method of cathode foil for aluminum electrolytic capacitors {ETCHING METHOD OF CATHODE FOIL FOR ALUMINUM ELECTROLYTIC CAPACITOR}

1 is a device schematic showing an apparatus of an etching method according to the present invention.

2 is a surface image photograph after the electrolytic etching according to the present invention.

The present invention relates to a method for improving the etching efficiency of a cathode foil for an aluminum electrolytic capacitor, and more particularly, in an electrolytic solution containing hydrochloric acid as the main component when an alternating current is applied to an aluminum foil in an electrolyte solution containing chlorine ions. The present invention provides a method for producing a cathode foil for an aluminum electrolytic capacitor, in which electrolytic etching is performed according to current density, temperature, and frequency by adding 0.1 to 0.5 N sulfuric acid to increase the surface area of the aluminum foil.

Aluminum electrolytic capacitors require high capacity as well as high capacity.As a general method of improving such capacity, aluminum electrolytic capacitors are electrochemically etched by superimposing direct-current, alternating current, direct current or alternating current in an aqueous solution of high-purity aluminum foil in chloride solution. It is expanding. Low voltage anodic foils are used for etching mainly for alternating current electrolysis, while medium and high pressure foils are used for etching mainly for direct current electrolysis.

According to the present invention, various process variables (current density, electrolyte, temperature, and alternating frequency) have a great effect on the capacitance during alternating electrolytic etching. Its size and density are used to address these challenges and provide new ways to improve capacity and performance.

In the present invention to achieve the above object

When etching by applying an alternating current to an aluminum foil in an electrolyte solution containing chlorine ions, electrolytic etching is performed according to the current density, temperature, and frequency by adding sulfuric acid of 0.1 to 0.5 N in an electrolyte solution containing hydrochloric acid as the main component. The manufacturing method of the cathode foil for aluminum electrolytic capacitor which increases a surface area of foil and increases a capacitance is made into a main structure.

The production of the negative electrode foil for aluminum electrolytic capacitors subjected to electrolytic etching using an alternating current power source includes the concentration, temperature, current density, and concentration of the electrolyte solution. The capacitance value and etching pattern of the etching foil are also different depending on the influence of the frequency and the like.

As miniaturization of electronic devices, etc., the performance of aluminum electrolytic capacitors also demands miniaturization and high capacity. Conventionally, there has been a high demand for miniaturization of capacitors, and the capacity of the etched foil has been further demanded. Furthermore, increasing the surface area by performing electroetching without other additives is a technology required by the enterprise. It is to provide an etching method that can increase the surface area and increase the capacitance by improving the etching efficiency without lowering the mechanical strength of the.

Detailed description of the configuration is as follows.

Pretreating the aluminum foil in 5% phosphoric acid at 25-35 ° C. for 30 seconds to 3 minutes and then pretreating in hydrochloric acid for 30 seconds to 3 minutes to create an optimal surface condition where etching pits can be formed;

Etch in an electrolyte solution containing hydrochloric acid, but the concentration of the electrolyte solution is 0.1 ~ 0.5N sulfuric acid, aluminum current through the step of etching by adjusting the current density, temperature of the electrolyte solution, Cu content, Si content, Fe content contained in the electrolyte solution Etching method of the cathode foil for electrolytic capacitors is configured,

At this time, aluminum foil has a purity of 99.00 to 99.99%, a thickness of 0.010 to 0.030mm, preferably a purity of 99.97% and a thickness of 0.020mm.

In the electrolytic etching, the current density is 0.1 to 0.2 A / cm 2, the frequency is 0.1 Hz to 100 Hz, the temperature of the electrolyte is 35 to 95 ° C., and the content of Cu, Si, and Fe contained in the electrolyte is Cu 1 ~. 20ppm, Si 1 ~ 60ppm and Fe 1 ~ 65ppm, preferably in the electrolytic etching current density of 0.1 or 0.2 A / ㎠ at a frequency of 0.1 ~ 100kHz, the temperature of the electrolyte solution 40, 60, 90 ℃ Set the temperature as long as it is selected.

The current density is controlled in the range of 0.1 ~ 0.2A / ㎠, when used with a current density greater than 0.2 A / ㎠, the rapid oxidation occurs to reduce the specific surface area rather.

The frequency is used in the range of 0.1 to 100 Hz. If the frequency is lower than 0.1 Hz, the waveform is almost the same as the direct current so that no AC etching occurs. At high frequencies, that is, the specific surface area increases and decreases due to the waveform. This happens.

The temperature of the electrolyte is used in the range of 35 ~ 65 ℃, has a disadvantage that the reaction proceeds rapidly as the temperature increases so that the time of the oxidation reaction is extremely short and fast to be inadequate for etching.

In addition, the amount of metal contained in the electrolyte during the electrolytic etching is very important. The etching surface varies considerably according to the concentration of the contained metal, and the amount of copper is contained in an appropriate amount or more, so that the galvanic electric potential during etching is increased. In addition to electrical etching, chemical etching is also performed simultaneously.

Therefore, when the concentration of metal increases, the reaction occurs rapidly on the surface, and the corrosion rate increases rapidly and the specific surface area decreases. In particular, since the thickness of the cathode foil is thin, it is used in the range of Cu 1 ~ 20ppm, Si 1 ~ 60ppm and Fe 1 ~ 65ppm.

Hereinafter, the configuration according to the present invention will be described in more detail with reference to the following examples.

Example

High purity aluminum foil having a purity of 99.97% and a thickness of 0.020 mm was pretreated with 5% phosphoric acid at 30 ° C. for 1 minute, followed by pretreatment with hydrochloric acid for 1 minute.

The equipment for etching is shown by FIG. Etching was performed in an electrolyte solution containing hydrochloric acid according to the present invention, and the concentration of the electrolyte solution was etched by adding 0.5 N sulfuric acid. At the time of etching, the current density is 0.1 A / cm 2, 0.2 A / cm 2, the frequency is 100 Hz, the temperature of the electrolyte is 40, 60, 90 ° C. The Cu content in the electrolyte is 20ppm or less, Si content is 60ppm or less, Fe The content of is maintained below 65ppm. The surface of the aluminum foil etched as described above is shown in FIG. 2.

The etching method of the negative electrode foil for aluminum electrolytic capacitors according to the present invention can be produced using a relatively simple method for the negative electrode foil for aluminum electrolytic capacitors, it is possible to manufacture a high capacity negative electrode foil.

Claims (5)

Pretreating the aluminum foil in 5% phosphoric acid at 25-35 ° C. for 30 seconds to 3 minutes and then pretreating in hydrochloric acid for 30 seconds to 3 minutes to create an optimal surface condition where etching pits can be formed; Etch in an electrolyte solution containing hydrochloric acid, the concentration of the electrolyte solution is 0.1 ~ 0.5N sulfuric acid is added, the current density of 0.1 ~ 0.2 A / ㎠, electrolyte temperature of 35 ~ 65 ℃, Cu 1 ~ 20ppm contained in the electrolyte, Si 1 ~ 60ppm, Fe 1 ~ 65ppm; etching method of the cathode foil for aluminum electrolytic capacitors, characterized in that through the. delete delete delete The method of manufacturing a cathode foil for aluminum electrolytic capacitors according to claim 1, wherein the aluminum foil has a purity of 99.00 to 99.99% and a thickness of 0.010 to 0.030 mm.

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