Background Theory > From Concept to Creation: Mastering PCB Design > Documentation and Communication > Generating and understanding Gerber files

Gerber files are the industry-standard format used by PCB (Printed Circuit Board) fabrication houses to produce the electronic circuits on a board. These files are generated once the PCB design is complete and are ready for manufacturing. They contain information about the copper tracking layers, drilling patterns, component notations, and other features on the PCB.

Here's a deeper look into generating and understanding Gerber files:

Generating Gerber Files

•Finalize PCB Design: Before generating Gerber files, ensure your PCB design is complete and thoroughly checked for errors, including trace routing, component placement, and overall functionality.

•Layer Selection: Determine the necessary layers for your PCB (e.g., top, bottom, solder mask, silkscreen, etc.) and ensure they are properly configured in your PCB design software.

•Gerber Generation Process:

oMost PCB design software has a dedicated function for generating Gerber files. This usually involves going to a menu like 'File', then selecting an option such as 'Export' or 'Plot', and finally choosing 'Gerber files'.

oYou'll likely have options to select the specific layers and additional settings relevant to the Gerber output.

•Settings Configuration: Configure the necessary settings in the dialog. This may include specifying the number of layers, the units (millimeters or inches), format details, and other parameters based on your PCB requirements and your manufacturer's specifications.

•File Generation: After setting the configuration, proceed with the file generation. The software will create a set of Gerber files, usually compressed into a single .ZIP file for ease of transport.

•Review and Validation: Use a Gerber file viewer to review the generated files. This step is crucial to verify that the output matches your design intention.

Understanding Gerber Files

Each file corresponds to a specific layer or function of the PCB. Common layers include:

•Copper Layers: These files define the copper paths or traces on the PCB. Separate files are used for the top and bottom layers in a two-layer board, and additional files are used for multi-layer boards.

•Solder Mask: The solder mask files indicate where the solder mask material will be applied on the board. There are usually top and bottom solder mask files.

•Silkscreen: These files provide information for text or symbols that will be printed on the outward-facing sides of the PCB, like component labels, logos, and test points.

•Drill Files: Drill files (often in Excellon format) specify the locations and sizes of holes to be drilled in the PCB.

•Board Outline: This file defines the physical shape and size of the PCB, including any cutouts or irregularities.

•Aperture File: Older Gerber formats also require an aperture file that defines the shapes and sizes of all the 'flashes' (pads) and 'draws' (tracks, lines, and outlines) used in the design.

Communication with Manufacturer

•Specifications: It's crucial to understand and adhere to your manufacturer's specifications for Gerber files, as these may vary slightly among different companies. Incorrect settings can lead to manufacturing errors.

•Submission and Confirmation: Once you submit the Gerber files to your manufacturer, they should provide a confirmation review, often using a Gerber file viewer to ensure everything is in order.

•Feedback and Adjustments: Pay attention to feedback from the manufacturer. They may spot issues you missed or request certain adjustments to fit their manufacturing capabilities.

Conclusion

Gerber files act as the bridge between your digital PCB design and the physical board production, essentially serving as the manufacturing blueprint for your PCB project. Generating these files with attention to detail and understanding their structure and purpose is fundamental to ensuring the manufacturability of your designs and achieving functional, high-quality boards. Always communicate closely with your PCB manufacturer to ensure compliance with their specifications and to facilitate a smooth production process.