A lithographic technique used to transfer the design of circuit paths onto printed circuit boards as well as the circuit paths and electronic elements of a chip onto a wafer's surface.
A photomask is created with the design for each layer of the board or wafer (chip). The board or wafer is coated with a light-sensitive film (photoresist) that is hardened when exposed to light shining through the photomask. The board or wafer is then exposed to an acid bath (wet processing) or hot ions (dry processing), and the unhardened areas are etched away. See chip
and printed circuit board