Gerber files in EAGLE

I have worked with files describing electronic schematics and PCB board layout. But so far I have never really worked with Gerber files myself. As I found out it’s not rocket science, it’s not complicated at all.

The Gerber format is used to describe monochrome vector images by an ordered stream of graphics objects. The format uses printable ASCII (7 bit) characters only.

The schematic and PCB design software EAGLE provides a job mechanism with the aid of which the creation of the output data for a board can be automated (CAM). This tool can be used to create Gerber files. The predefined job is called gerb274x.cam.

For a 2-layer PCB the standard process will lead to five Gerber files (where cmp stands for component side and sol for solder side):

  • Copper, component side (.cmp)
  • Copper, solder side (.sol)
  • Silk screen, component side (.plc)
  • Solder stop mask, component side (.stc)
  • Solder stop mask, solder side (.sts)

You might want to add (if your manufacturer allows you to have it:

  • Silk screen, solder side (.pls)

Additional steps: you may want to add a drill file, specified by the Excellon file format. That’s another job in Eagle called excellon.cam. The Excellon format (variant of the RS-274-C standard) is widely used to drive CNC drilling and routing machines in PCB manufacturing.

This will create the following two files:

 

  • Drill file (.drd)
  • Drill Station Info File (.dri)

The drill file is used by a drill program and includes sizes and locations of holes in the PCB.

To check my results I used the gerbv tool under Linux:

gerbv
Screenshot of gerbv tool

References:

 

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