Gerber: basics, file name extensions and viewer

Whichever program you use for PCB layout, the final output will be a set of gerber files. Gerbers are just text files with co-ordinate positions and other info, which tell your vendor which parts of the board must have copper (or overlay or solder mask, etc. depending on the layer) and which parts must not. It is always a good idea to talk to your PCB vendor and find out the gerber format (version, units, number format, leading/trailing zeros, etc.) in which they need the files. If you are not able to contact the vendor while generating the gerbers, it usually works if you attach a ReadMe file listing the configuration along with the gerbers.You might also have to generate NC drill files separately.

The file name extension for gerbers varies with PCB software. For Eagle, OrCAD or Protel, refer here. For Altium, here.

It might also help to view gerber files in a third party viewer before sending the files to the vendor. Pentalogix’s ViewMate and gerbv are good viewers that you can download for free.