View attachment 147495for example on this am using a spiral carbide engraving bit of 0.1mm 10 degree but some pad are well done but other copper are being removed how can i collect them
You'll need one or more of the following...
- a better quality (flatter) board
- a better way to clamp the board to avoid cupping/bending of the board from flat
- a vacuum table that is extremely flat
- a gantry for your cnc with straight rails and essentially no flexing.
- no up/down movement of your shaft in the quill
Flatness over a large area is pretty difficult for a multilayer organic/inorganic multilayer. Any stress in the materials during fabrication of copper foil, epoxy resin, fiberglass mat, epoxy, fiberglass mat, epoxy, copper foil - your board will twist/warp with temperature changes (and it does and it may not even be flat from the beginning). If you have a single-sided copper board, you'll get even more warpage and unevenness.
Remember, you're only removing about 35 micrometers of copper so flatness must be better than the depth you are penetrating the epoxy resin below the copper.