I'm making a project, but my arduino pro micro is just slightly too big to fit in it's case.

What would happen if I cut off the pin holes that I don't need? Would it still work? Or would it be ruined?

  • 1
    Hello and welcome! Do you mean cutting the pins (as suggested in the questions) or cutting the printed circuit board itself (as hinted in the title)? – Ghanima Apr 29 '17 at 15:08
  • Cutting the printed circuit board itself – M. Collins Apr 29 '17 at 15:09
  • If you don't accidentally cut any other traces you'll be fine. I think most board don't snake any traces around the pins, but you'd have to check yourself, or post a detailed picture. Where did you buy your pro micro, as there are a few variations of the same board? – Gerben Apr 29 '17 at 15:15
  • I bought a fake Chinese one from eBay – M. Collins Apr 29 '17 at 15:17

I guess that one could cut (or hone down) parts of the PCB. Obviosly this process devoids the warranty and there is the risk of damaging either the board or some components on it (i.e. by holding or clamping it during the process).

I would not expect any other wiring besides those connecting the pins to run in this part of the PCB. The reference layout (see board layout and using Eagle (free version)) - if the clones follow that layout - confirms that there are no other traces there. So it is mostly important to not cut any other traces and remove any chippings after the cutting to avoid short circuits.

If in doubt buy two or three boards ;) to try and repeat the process.


Rather than trying to modify the board (which I think is a bad idea) why not use a Pro Mini.

These are smaller (and cheaper), and almost identical in function, apart from the USB interface. You do need a serial interface (or ICSP) to program.


This is a bad ideas:

  • the PCB is made of fiber glass which, when broken, cut or filed, produces a very fine powder; any powder you might breath in during the process wil stay in lungs for a very long time, in the order of decades

  • the risk of cracking traces running close to the are of cut, even if they are not directly being cut, is pretty high; the copper traces rely on the fiberglass rigidity, but a crack in the fiberglass propagating under the traces is welcoming a broken trace

Go for a different case, if that's not a viable option go for a barebone arduino. If that is also a non viable option consider the idea of producing a few custom PCBs: they are not that expensive!


You could use a Pro Mini as Milliways suggested, but you don't necessarily need a USB interface to programme it. You can use your Arduino UNO to directly programme the Arduino Pro Mini.

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