Etched Circuit-Board Manufacturing Overview

by Dennis L Feucht

Long ago, circuit boards were made by printing metal onto an insulating plane of plastic material, such as phenolic or fiberglass. Nowadays, fiberglass boards with a layer of copper are etched, leaving copper where connections are to be made. The etch pattern is created by first covering the board with a thin layer of photo-resist. Upon this light-sensitive layer is placed a photographic film created by a photo-plotter from the board layout files. The photo-resist is exposed to ultraviolet light. For positive resist, the UV light hardens it by polymerization so that the unexposed resist can be washed off, leaving a resist pattern where copper is desired.

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