Circuit board glossary

Item: Gerber data

Description:

The Gerber data type consists of graphics commands, which specify a circuit layout by x- and y- coordinates and vectors. Originally developed for the control of photoplotters, it is now the most widely used format for transfering data from PCB design (CAD) to the manufacturing process (CAM). Every PCB manufacturer is able to process Gerber data.

The offical names for Gerber data are

  • RS-274-D, Standard Gerber without aperture data or
  • RS-274-X, Extended Gerber including aperture data (D codes)

The format of Standard Gerber (RS-274-D) consists of files for the individual layers, a D-code list with aperture data and a file for the layer structure. Especially the extra D-code list can cause compatibility problems.

Therefore the most common format is Extended Gerber (RS-274-X), also called XGerber, since the extra D-code list for the aperture data is already included. Each Gerber file stands for a single layer of the PCB, such as marking print, solder-stop and copper (conductors) or holes (pads) in SMD stencils.

In addition to the Gerber data, the PCB manufacturer still needs the drill data (coordinates, type and diameter of the holes) mostly in the data format of Excellon or Sieb & Meyer.

Due to possible problems with the import and export of Gerber files, many manufacturers now accept ODB + + data, which does not allow such a mistake. In any case, you should check your Gerber data export with an independent software, e.g. the Gerber data viewer GC Prevue from Graphicode.