[sdiy] PCB faceplate large hole creation?

[Brian Willoughby]

That "0.2mm from edge" rule is not only about the routing accuracy. It also affects layers shorting to each other and/or shorting to the case (assuming a metal or conductive case).


I once toured a fab house who bragged about their engineering staff who "fixed" things. She told a story about a military contractor during the Gulf War who used them for prototypes, won the contract bid, but then switched to another fab house to save money. The result? Tens of thousands of military radios delivered to the desert that would not work because the PCB power rails were shorted to the case. Turns out the layout designer had allowed copper layers to be 0.0mm from the edge and the prototype fab house had "corrected" that. The cheap fab house did not.

Of course, my silent response was, "That's not a thing to brag about!"

(not to mention: anyone who switches fab houses without a prototype run to confirm 100% functionality is getting what they asked for)

Later, I confirmed with larger clients in the music industry that they have contracts with fab houses (and everyone else) stating that any changes to engineering design files must be looped back to them and approved. A smart company knows that they need to own all of the IP so that they can switch fabrication and assembly - whether due to someone going out of business, or just being out-bid - and still be able to manufacture "the same product" anywhere.


Another issue is that panelized boards need to be held in some sort of frame for assembly, and if all of your components are close to the edge then they can't do that. But this is more of an assembly limitation and not a PCB fab limitation. They're still related, though.

Brian Willoughby


On May 28, 2021, at 02:16, Mike Bryant <mbryant at futurehorizons.com> wrote:
> Depends on your vendor.  For JLCPCB it seems to be the outer edge, not the centre line, as their DRC allows tracks within 0.2mm of the edge (not that I ever put them that close), and they route the outline with a 0.65mm mill if not done with laser.