Etching (chemical machining)

Etching is a material-removal process in which chemical reactions dissolve selected areas of a surface. Masks or controlled exposure determine where material is removed and how deep the resulting features are.

Etchant: A chemical reagent that dissolves or reacts with a material during etching. The etchant supplies the reaction that removes exposed material.
Photochemical machining: A manufacturing process that uses patterned light-sensitive masks and chemical etching to cut thin metal parts. It applies etching to produce intricate sheet-metal components without cutting forces.
Chemical reaction: A process in which substances are transformed into other substances through rearrangement of atoms. Etching removes material through reactions between the surface and reactive chemicals.
Milling (machining): A machining process that removes material with a rotating cutting tool. Milling removes material by physical cutting, unlike chemical dissolution.
Etch mask: A protective layer that prevents an etchant from reaching selected parts of a surface. Masking defines which regions remain while exposed areas are dissolved.
Printed circuit board: An insulating board with patterned conductive pathways that electrically connect electronic components. Chemical etching removes unwanted copper to leave circuit traces.
Oxidation-reduction reaction: A chemical reaction involving transfer of electrons between reacting species. Many metal etchants dissolve surfaces through coupled oxidation and reduction.
Electrochemical machining: A machining process that removes conductive material through anodic dissolution in an electrolyte. It uses electrical current to drive dissolution rather than relying solely on chemical attack.
Photoresist: A light-sensitive polymer film used to transfer patterned exposure into a protective or reactive surface pattern. Photoresist commonly forms the patterned mask that guides chemical removal.
Microfabrication: The fabrication of structures and devices with micrometer-scale features. Etching is one of the core methods for shaping microscopic devices.

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