Gerber files for PCB: How are they important in manufacturing your printed circuit boards?

Gerber files are the most commonly accepted design file formats to fabricate and assemble printed circuit boards. They ensure an efficient manufacturing process by standardizing the design data transfer from engineers to PCB manufacturers. Once you complete the circuit design and proceed to order placement, your contract manufacturer will ask for the design files to accurately build your PCBs. If there are any errors in your shared data, then defective boards, extra costs, and time delays are inevitable. To avoid such consequences, Gerber files play a crucial role in PCB manufacturing.

What is a Gerber file? What information does it include?

Gerber files are a set of ASCII vector format files that are used to define the PCB design specifications. They are generated using Electronic Design Automation (EDA) or Computer-Aided Design (CAD) tools to provide information on board configuration parameters, aperture descriptions, XY coordinate locations, and drawing commands. The configuration details are the size and shape of the PCB to be fabricated. Each board layer information is captured in separate files defining the circuit board components like copper traces, pads, vias, solder mask, silkscreen, logos, etc. The position of each geometrical shape as X-Y coordinates are mentioned in the Gerber files and commands are used to draw these shapes on physical boards.

The essential elements of a Gerber file are the board dimensions, outline, top assembly, top silkscreen, top mask, top paste, top copper, inner signal, inner plane, bottom copper, bottom paste, bottom mask, bottom silkscreen, bottom assembly, and fab (giving details of stack-up, drill details, cut-outs, etc). Gerber file extensions generated by Computer-Aided Manufacturing (CAM) tools can be selected by the user. Typically, project names with extensions such as “.TOP” for the top layer, “.BOT” for the bottom layer, and “.drl” for drill hole data are used.

Importance of Gerber files in PCB manufacturing:

A PCB designer has to create the Gerber files using an EDA tool compatible with the PCB manufacturer’s system. Any mismatch in the format or tool version can cause a delay in the fabrication process. The primary purpose of Gerber files is to deliver a reliable PCB order within the expected timeline. There are multiple advantages of using Gerber files in PCB manufacturing as follows:

1. Gerber files offer intricate design details that can assist PCB manufacturers in building high-quality circuit boards. Contract manufacturers can rely on these files to determine the precise dimensions, pad locations, trace widths, and silkscreen legends to be printed on the board. The accurate data provided by the Gerber files can minimize potential manufacturing errors.
2. They are compatible with a wide range of CAM tools used by PCB manufacturers. The Gerber files are easily exported from most EDA tools and ensure a smooth transition from design to the production stage in the PCB development cycle. Further, the flexibility of the data format allows contract manufacturers to implement different fabrication and assembly methods, supporting advanced technologies.
3. The standard format of Gerber files has a key role in establishing a seamless PCB manufacturing process. These files are readable and easily used by different stakeholders like design engineers, layout experts, and assembly line technicians. So, there is reduced ambiguity and minimal reworks in the overall PCB manufacturing process.
4. Usually, contract manufacturers use Gerber files to run Design for Manufacturability (DFM) checks that allow them to assess the production yield. Also, the same files are used to create fixtures for board inspection and testing. Thus, Gerber files help in the quality control of PCB production.

With the evolving PCB manufacturing processes, design output files have also been upgraded. There are different output files available for PCB fabrication, but the Gerber files remain the most compatible and versatile file format so far.

Gerber file versions and other output formats:

Usually, the board specifications and complexity determine the type and number of Gerber files generated. Different Gerber file formats vary in their data structure but are used to create stencils for PCB fabrication.

RS274-D is the standard Gerber file format and is denoted in the numerical control format. It consisted of XY coordinates and drawing codes. This format is represented with an extension “.gbr” and gained a lot of popularity in the initial days. But this variant requires manual assigning of the aperture codes to generate accurate Gerber files. So, the extended Gerber format was created.

RS274-X is the revised version with an extension “.gbx”. It is in ASCII format and includes all four components of Gerber information (configuration parameters, aperture drawings, XY coordinates, and drawing commands) in one file. In this format, aperture positions are automatically updated.

Gerber X2 is the latest version of Gerber files with additional data like layer stack details, via and pad attributes, impedance-controlled traces, etc. The supported file extensions are “.top”, “.bot” and more. This format is backward compatible with the RS274-X version, yet includes a big set of manufacturing data. Gerber X2 largely eliminates issues like file errors and data ambiguity.

Open Database (ODB) ++ is another data exchange file format that includes the complete information necessary to define a PCB layer in one file. It enables the designer to capture all the data required for DFM checks. For instance, it includes board stack-up, Bill of Materials, dimensions and drill details in one file. It is supported by major CAM and DFM tools.

IPC-2581 is the latest standard for PCB data organization and exchange from CAD to CAM systems during the fabrication and assembly process. It is an open standard for data transfer with no manual intervention. An XML-based file is used to provide all the manufacturing data required by the CAM systems. This standard allows the extraction of design data without any interpretation into CAM systems.

Conclusion

Gerber files are the universal data transfer formats used in the PCB manufacturing industry. They enable high-yield mass production of your PCB products. The latest version, Gerber X2 is popular among PCB manufacturers for delivering high-performance and reliable PCBs. These Gerber files reduce fabrication errors, increase profits and boost product-to-market timelines.

Technotronix is one of the leading providers of PCB manufacturing services to all the dominant industries. Having a strong manufacturing unit with a strong tool room and a team of experts, we are the one that provides cost effective solutions with keeping quality at the nucleus in each stage of PCB manufacturing.

For any kind of PCB requirements, feel free to contact us or drop an email to us at sales@technotronix.us or call us on 714/630-9200.