Fabrication of precise copper micro-coils using electrolytic etching

Precise and homogeneous copper micro-coils were fabricated using electrolytic etching in aqueous solution of sodium chloride and ammonium chloride. It was clarified that the etching rate was hardly influenced by the resist pattern thickness and the etching voltage, but only depended on the helical space pattern width. Start and stop of the etching was exactly controlled by switching on and off the power supply circuit, and the etching was practiced under the room temperature without heating the specimens. The sidewall surfaces of the etched coils were very much smoother than those of the coils fabricated by the conventional chemical etching, and very favorable coil width homogeneity was obtained even for narrow space patterns with a width around 10 μm.

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► Helical patterning on copper pipes.
► Electrolytic etching.
► Precise micro-coils.