This isn't a replacement for the dimension details we added in the last step -- The silk screen on your PCBs isn't very reliable since it often gets shifted a bit to the side during manufacturing -- but it's worth adding as a visual indicator for assembly.
The process is identical to the way we added our dimension details in the last step, but there are a few things to keep in mind here:
The following guidelines are a good starting point when adding a printer outline to your PCB:
- Always place the lines or text on Layer 21 (tPlace)!
- Be sure not to place any lines on top of the copper pads, since you can't print silk screen on bare copper pads!
- Create your outline slightly larger than the actual physical dimensions, so that you can still see the outline once the part is physically place (perhaps 0.1 - 0.2mm larger on each side)
The silk screen outline is drawing exactly the same way as out dimension details in the previous step ... using the 'Wire' tool.
The important thing here is to make sure that you are on the right layer, Layer 21 (tPlace):
Something like this should be fine. It's a bit bigger than I would usually place, but this avoids any overlap on the pads, and everything is smaller looking than you think when you actually see it on a PCB: