Slots, milling, contour and rout-outs have to be indicated clearly to be processed correctly in production.

  • Do not indicate them in your cupper layers or textprint layers
  • Do not indicate them by putting text outside your layout
  • Do not indicate them by adding a textfile or any other document together with your datafiles.


  • Do indicate the slots, milling and routing information into a mechanical layer. A mechanical layer consists of the border of the PCB, together with any other mechanical finishings like extra milling, routing or slots.
  • The size of the slots can be indicated in text together with tolerances ( if needed).
  • Indicate only one border in your mechanical layer. If you want a round shaped PCB then we expect a round shaped contour,
    not a round shaped PCB inside a square box, as this will result in a square shaped PCB…


  • Acceptable contour file indicating slots. The contour layer has to have the same offset as the other copper layers in order to align copper and routing together.
  • Contour and slots
  • Properly aligned layers – correct offset to the contour layer
  • Correct aligned slots
  • Not correctly aligned layers – incorrect offset to the contour layer
  • not correct aligned slots
  • Example of acceptable drillmap file indicating slots
  • Drillmap indicating slots
    • Note that the contour layer is drawn with a normal linewidth (0.2 mm). Do not use the thickness of the router to avoid confusion about the correct dimensions of the PCB. We consider the midpoint of the line as indicator of the correct dimension.
    • Slots will be PTH when copper pads are present on top and bottom layer (comparable rule as with normal plated through holes).
    • Slots will be NPTH when no copper pads are present on top and bottom layer (comparable with normal non-plated through holes).
    • When you need a NPTH slot and copper pads are present, then you will have to indicate this clearly in your design – see example below:
  • Indication of NPT holes

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