Research On Etching Process Of Aluminum Cathode Foil For Aluminum Electrolytic Capacitor

In order to meet the needs of high integration and miniaturization development of electronic devices, modern electronics market demands for low volume and high specific capacity of aluminum electrolytic capacitor. However, low volume and high specific capacity are limited by the specific surfaces of cathode and anodic foils used in aluminum electrolytic capacitor. In this paper, the effects of corrosion inhibitor on aluminum foil were studied by increasing the specific surface area of anode foils.Pretreatment was realized by alkaline method before etching process. Experiments results demonstrated an optimal pretreatment condition: the alkaline (NaOH) concentration is6%-8%, pretreatment duration is60～70s, and the treating temperature is45～50℃.The effects of the concentration of HCl and H2SO4, etching duration and etching temperature on chemical etching process were investigated and a proper etching process was obtained:the etching solution is composed of1.5mol·L-1～2mol-L-1HCl and0.2mol-L-1H2SO4, etching duration is55s-60s, etching temperature is45℃. An etched aluminum foil with the highest specific capacitance of223.7μF·cm-2was obtained when the concentration of HCl and H2SO4is2mol-L-1and0.2mol·L-1, the etching duration is60s when the etching temperature is45℃. Under these conditions, the weight-loss ratio is25.76%and uniform pores were generated on the surface of the etched foil.The addition of corrosion inhibitor can effectively suppress the etching reaction, which results in discrete pores and a low specific capacity. By adjusting the etch process, the specific capacity of aluminum foil can be further improved and etching holes with homogeneous morphology could be obtained.With the addition of thiocarbamide, a proper etching process was obtained:the concentration of thiocarbamide is0.5g·L-1，the etching solution is2mol·L-1HCl+0.2mol·L-1H2SO4, etching temperature is60℃, etching duration is70s, Under these conditions,the etched foil specific capacitance is246.9μF·cm-2.With the addition of methenamine, a proper etching process was obtained:the concentration of methenamine is0.1g-L-1，the etching solution is2mol·L-1HC1+0.2mol·L-1H2SO4, etching temperature is55℃etching duration is70s, Under these conditions,the etched foil specific capacitance is268.5μF·cm-2.