Removing process of residual copper on cathode foil surface for improved aluminium electrolyzing capacitor

Abstract

This improvement method relates to removing of the residual copper on the surface of the cathode foil, it is used in the aluminum electrolytic capacitor. The cleaning solution is hydrogen nitrate, and there is buffer in the cleaning solution, the buffer is soluble salt which contains element of CrO4 2- or PO43- or peptide amine or six-methyl fouramine. The weight of the buffer is 0.1-8% of the cleaning solution, the concentration of hydrogen nitrate uses in cleaning solution is 50-75 wt %, the temperature of it is 25-40DEG C, the time of immersion is 30-45s. This method can remove the residual copper on the surface of cathode foil, which belongs to the hard or soft electrical aluminum foil and is experienced the corrosion treatment. It can reduce the content of the copper on the cathode foil below 3mg / m2. This method is simple and easy to produce continuously, it can not affect the specific volume and mechanical intensity of the cathode foil, and it increases the lifetime of the aluminum electrolytic capacitor. At last, it doesn't contain the extraction of copper in this method, so the cost can be controlled.

Description

technical field [0001] The invention relates to a method for removing residual copper on the surface of cathode foil for aluminum electrolytic capacitors. Background technique [0002] Chinese patent CN03150482.5 discloses a "method for removing residual copper on the surface of negative aluminum corrosion foil for aluminum electrolytic capacitors", which uses high-concentration nitric acid in the cleaning tank to add copper ion complexing agent as cleaning liquid, and uses electrochemical electrolysis to extract Copper device, cleaning chlorine ions and residual copper at the same time, the concentration of nitric acid is 20-60wt%, the temperature of the nitric acid solution is 15-60°C, the immersion time is 5-90s, and 100-600ppm of copper ions are added to the solution for complexation agent, although this method can effectively reduce the residual copper content on the surface of the corroded foil to 5mg / m 2 The following, but the existing shortcomings are also obvious, ...

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Problems solved by technology

[0002] Chinese patent CN03150482.5 discloses a "method for removing residual copper on the surface of negative aluminum corrosion foil for aluminum electrolytic capacitors", which uses high-concentration nitric acid in the cleaning tank to add copper ion complexing agent as cleaning liquid, and uses electrochemical electrolysis to extract Copper device, cleaning chlorine ions and residual copper at the same time, the concentration of nitric acid is 20-60wt%, the temperature of the nitric acid solution is 15-60°C, the immersion time is 5-90s, and 100-600ppm of copper ions are added to the solution for complexation agent, although this method can effectively reduce the residual copper content on the surface of the corroded foil to 5mg / m 2 The following, but the existing shortcomings are also obvious, that is, nitric acid used as a cleaning solution is highly corrosive, and it also damages the cathode foil in the process of removing copper ions, reducing the specific volume of the cathode foil, making its electrical performance and service life In addition, copper ion complexing agent is used to extract copper in the method, because the residual copper on the surface of cathode foil is still relatively small, the copper content of hard electronic aluminum foil is 0.18-0.25%, and the copper content of soft electronic aluminum foil The content is 0.06-0.12%, and the thickness is 15 μm-60 μm. In fact, the device for extracting copper in the method has no practical significance, but increases the equipment investment and operation cost; moreover, although the technical parameters controlled in the process can reach The effect of removing copper ions, but it cannot adapt to the continuous operation of large-scale production. After about 12 to 16 hours of continuous operation, the residual copper ion content on the surface of the cathode foil is greater than or equal to 10mg / M2, and one-third of the cleaning solution needs to be removed. Replenish new liquid to continue the process