Printed Circuit Board Milling
Printed circuit board milling (also known as : isolation milling) is the process of removing areas of copper from a sheet of printed circuit board material to recreate the pads, signal traces and structures according to patterns from a digital circuit board plan known as a layout file. Similar to the more common and well known chemical PCB etch process, the PCB milling process is subtractive: material is removed to create the electrical isolation and ground planes required. PCB milling has advantages for both prototyping and some special PCB designs. Probably the biggest benefit is that one doesn't have to use chemicals to produce PCB's.