Printed circuit board modification process

摘要

A process is provided for modifying internal circuits in a multilayer printed circuit board by modifying the glass master which produces the internal circuit patterns. An inexpensive film copy of the glass master to be changed is used to identify the circuit lands to be removed. Holes are made in the film at these locations thereby removing the image of the land and these alterations are verified in accordance with the engineering change instructions. The perforated film is used as a template to alter the glass master by removing the emulsion through the holes in the film and then the glass master is verified and used to produce the modified circuit board.