These circuit board blanks are made by bonding a thin layer of 1 ounce of copper over one or both sides of the entire substrate. To etch a circuit design into the material, unwanted copper can be removed using a CNCmachine, leaving only traces. Free software like Eagle CAD, a vector based 2D program like Inkscape or a 2D raster program like gimp will work for designing circuit patterns to upload to the machine for milling. The circuit can also be drawn on the boards using a chemical mask pen and then chemically etched to remove the unwanted material.
The more commonly available FR-4 boards have a fiber glass, non-conductive layer which wears the bits on the machine very fast and will produce undesirable fiber glass dust during machining. These FR-1 boards are made with a cellulose paper-based material which makes the dust less toxic and the resin binder is soft enough that the bits last much longer.
