Gerber format

[1] It is the de facto standard used by PCB industry software to describe the printed circuit board images: copper layers, solder mask, legend, drill data, etc.

[5] Fabrication data contains a Gerber file for each image layer and drill span (copper layers, solder mask, legend or silk...) (For historic reasons drill data is also transferred in NC formats although Gerber files are often of better quality.

)[14] Typically, all these files are "zipped" into a single archive that is sent to the PCB bare board fabrication shop.

The fabricator loads them into a computer-aided manufacturing (CAM) system to prepare data for each step of the PCB production process.

[15] The .FileFunction attribute is the standardized method to link each layer in the PCB with its corresponding Gerber file in the fabrication data.

[1]: Section 5.6.3 of the 202308 release of the Gerber Layer Format Specification If attributes are not supported, then only informal methods are available.

[20] The material stack up, components and finishes are typically provided in informal text files or drawings.

Attributes are akin to labels providing information associated with image files, or features within them.

Standard Gerber was a simple ASCII format consisting of commands and XY coordinates.

[1][30] Standard Gerber supports only the simple imaging operators that a vector plotter is capable of - drawing tracks and flashing apertures.

Copper pours must be created by painting (aka stroking or vector-filling) them with a vast number of tracks.

Painting creates the intended image but results in very large files that take long time to process and need error-prone manual work in CAM.

[17][24][31][32] Standard Gerber was intended for a manual workflow using an NC machine called a vector photoplotter: the plotter operator loads the paper tape with the Standard Gerber file on the plotter, manually sets the coordinate unit on the machine console and mounts the aperture wheel described in the accompanying wheel file.

Standard Gerber is not suitable for automated data transfer between PCB designers and manufacturers.

In 1991 with the availability of the more capable raster photoplotters, the Gerber format was extended with polygon areas and "mass parameters".

The result was a simple, but powerful format, focused on the current needs of the PCB industry.

This version of the Gerber format was developed by Karel Tavernier and Rik Breemeersch from Ucamco.

[1][43] In August 2015 Ucamco published a draft specification adding nested step and repeat and block apertures to make panel descriptions more efficient, calling for comments from the user community.

[45] In July 2016 Ucamco published a draft specification to include netlist information in Gerber, calling for input from the user community.

[1][19] In March 2017 Ucamco published a draft specification to include fabrication documentation in Gerber calling for input from the user community.

[22] In June 2017 a free online Reference Gerber Viewer[13] was made available by Ucamco as a complement to the specification.

[49] In October 2019 Ucamco published a draft specification to include component information in Gerber data, calling for comments from the user community.

View of a Gerber format file