Excellon file (Drill file)

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In electronics manufacturing, an Excellon file is a text-based file format which is used

to control the actions of a CNC drilling machine, commonly used in the drilling of

printed circuit boards (PCBs).


The Excellon file format is a variant of standard RS-274C.

It consists of commands to instruct a CNC drilling machine to drill holes of specific

diameters at specific locations on a PCB.


The name Excellon comes from the Excellon Automation Company, founded in

Torrance, California, USA in 1963 by inventor Joseph Smith.