| 摘要 |
PURPOSE: To provide a process for the production of shaped articles of niobium or tantalum by anodic etching of the metals covered with a structured photoresist mask in an aqueous etching solution containing hydrofluoric acid. CONSTITUTION: The process comprises the step of performing etching operation under electrochemical conditions under which a noise whose mean variation is 5 to 10 % of the absolute etching current is superposed on the resulting etching current and the etching solution contains a water-soluble polymer, wherein the polymer is polyethylene glycol having an average molar mass Mw of at least 100 g/mol, wherein the etching solution contains the polymer in a concentration of from 200 to 800 g/L, wherein the etching solution contains the hydrofluoric acid in a concentration of from 100 to 500 g/L, wherein the etching solution contains ammonium hydrogen fluoride in a concentration of from 10 to 100 g/L, wherein the temperature of the etching solution during the etching is from 5 to 70 deg.C, wherein the etching solution is agitated by a mechanical means or by blowing in air or a gas, inert to the niobium or tantalum sheet to be etched and to the etching solution, and wherein electrochemical potential of the niobium or tantalum sheet to be etched is adjusted by means of a potentiostat relative to a reference electrode present in the etching vessel close to the surface of the niobium or tantalum sheet.
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