Sam Jacoby

Gerber File Extensions

Posted . [Last updated . ]

Lest anyone be misled, this is a post about making circuit boards. Thrilling stuff.

Every time I send off Gerbers for production, I am baffled by the array of files that the CAM job in Eagle generates. I’m happy to be ignorant. That’s fine. The issue is, when you upload your files to most board fabs, they cheerily list the half-dozen odd things you’ve sent them—and ask you what they are? Top solder mask? NC drill file? I know nothing of this. So—some research later, and this is what we’ve got.

To the best of my knowledge—using Advanced Circuits, these are the file extension mappings using the Eagle Gerber RS274X cam file. I may have once changed the default extensions randomly a few months ago—so handle with care. There are some inconsistencies as detailed here. A nice summary here as well. Thanks, Fred.

At any rate, we’ll see how the boards come out:

  • .cmp / top copper

  • .drd / NC drill from

  • .dri / also an NC drill file. Do we need both? I don’t know. Probably not. But someone told me to generate the excellon paths once, so I do.

  • .plc / top silkscreen

  • .sol / bottom copper

  • .stc / top solder mask

  • .sts / bottom solder mask

  • .gpi / screw this one. General board info. Not needed.