What is Eagle .brd and Gerber Format?

Eagle .brd is the native file format used by Autodesk Eagle PCB design software for storing printed circuit board (PCB) designs. It contains all the information about the PCB layout, including component placement, routing, and layer stackup. However, to manufacture the PCB, the design needs to be converted into a standard format that can be understood by PCB fabrication machines. This is where Gerber files come into play.

Gerber format, also known as RS-274X, is a widely accepted standard for describing PCB designs. It consists of a set of files, each representing a specific layer of the PCB, such as copper traces, solder mask, silkscreen, and drill holes. Gerber files are essentially vector graphics files that use simple commands to define the geometry of the PCB FEAtures.

Why Convert Eagle .brd to Gerber?

Converting an Eagle .brd file to Gerber format is a crucial step in the PCB manufacturing process. Here are the main reasons why this conversion is necessary:

1. Compatibility with PCB Fabrication: Most PCB fabrication houses accept Gerber files as the standard input format. By converting your Eagle design to Gerber, you ensure that the manufacturer can easily process your design and produce the PCB according to your specifications.

2. Preserving Design Integrity: Gerber files provide an exact representation of your PCB design, including all the critical dimensions, apertures, and layer information. This helps maintain the integrity of your design throughout the manufacturing process, reducing the chances of errors or misinterpretations.

3. Easier Collaboration and Sharing: Gerber files are universally recognized and can be easily shared with team members, clients, or manufacturers. This facilitates collaboration and ensures that everyone is working with the same set of files, regardless of the PCB design software they are using.

Step-by-Step Guide to Convert Eagle .brd to Gerber

Follow these steps to convert your Eagle .brd file to Gerber format:

1. Open the Eagle .brd File: Launch Autodesk Eagle and open the PCB design file (.brd) that you want to convert.

2. Access the CAM Processor: From the main menu, select “File” > “CAM Processor”. This will open the CAM Processor window.

3. Load the Gerber CAM Job: In the CAM Processor window, click on “File” > “Open” and select the Gerber CAM job file (usually named “gerb274x.cam”). This file defines the Gerber output settings for each layer of the PCB.

4. Configure the Output Directory: Click on the “Output” tab in the CAM Processor window and specify the directory where you want to save the generated Gerber files.

5. Select the Layers to Export: In the CAM Processor window, you’ll see a list of all the layers in your PCB design. Select the layers that you want to include in the Gerber output. Typically, you’ll need to export the following layers:

6. Top Copper
7. Bottom Copper
8. Top Silkscreen
9. Bottom Silkscreen
10. Top Solder Mask
11. Bottom Solder Mask

12. Drill Files

13. Generate the Gerber Files: Click on the “Process Job” button in the CAM Processor window. Eagle will generate the Gerber files for the selected layers and save them in the specified output directory.

14. Verify the Gerber Files: Open the generated Gerber files using a Gerber viewer software to ensure that the output is correct and matches your PCB design. Check for any missing features, incorrect dimensions, or layer misalignments.

Layer	Gerber File Extension
Top Copper	.gtl
Bottom Copper	.gbl
Top Silkscreen	.gto
Bottom Silkscreen	.gbo
Top Solder Mask	.gts
Bottom Solder Mask	.gbs
Drill Files	.xln or .drd

Table: Common Gerber File Extensions for Different PCB Layers

Tips for a Successful Eagle to Gerber Conversion

1. Use a Standard Gerber CAM Job: Autodesk Eagle provides a default Gerber CAM job file (gerb274x.cam) that is compatible with most PCB manufacturers. Stick to this standard CAM job unless you have specific requirements from your manufacturer.

2. Include All Necessary Layers: Make sure to export all the required layers for PCB fabrication, including copper layers, solder mask, silkscreen, and drill files. Consult with your manufacturer if you are unsure about which layers to include.

3. Set Appropriate Aperture Sizes: Gerber files use apertures to define the size and shape of PCB features. Ensure that your design uses appropriate aperture sizes that can be reliably manufactured. Follow the guidelines provided by your PCB manufacturer regarding minimum trace widths, clearances, and hole sizes.

4. Verify the Gerber Output: Always review the generated Gerber files using a Gerber viewer before sending them to the manufacturer. Look for any discrepancies, missing features, or incorrect dimensions. Catching errors at this stage can save time and prevent costly manufacturing mistakes.

5. Communicate with Your Manufacturer: If you have any specific requirements or concerns about the Gerber files, communicate them clearly to your PCB manufacturer. They can provide guidance on how to optimize your design for manufacturing and ensure that the final PCB meets your expectations.

Frequently Asked Questions (FAQ)

1. What is the difference between Eagle .brd and Gerber files?
   Eagle .brd is the native file format used by Autodesk Eagle PCB design software to store the PCB layout information. It can only be opened and edited within Eagle. On the other hand, Gerber files are a standardized format used for PCB fabrication. They contain the necessary information for manufacturing the PCB, including copper layers, solder mask, silkscreen, and drill data.

2. Can I send Eagle .brd files directly to a PCB manufacturer?
   While some PCB manufacturers may accept Eagle .brd files, it is generally recommended to convert them to Gerber format before sending them for fabrication. Gerber files are the industry standard and ensure compatibility with the manufacturer’s equipment and processes. Most manufacturers prefer Gerber files as they provide a clear and unambiguous representation of the PCB design.

3. What if I don’t have the Eagle software? Can I still convert .brd files to Gerber?
   If you don’t have access to Autodesk Eagle, you can use third-party tools or online services that can convert Eagle .brd files to Gerber format. Some popular options include PCB2Gcode, FlatCAM, and EagleUp. These tools typically require you to upload the .brd file and then generate the Gerber files based on your specified settings.

4. How do I know if my Gerber files are correctly generated?
   To verify the correctness of your Gerber files, you can use a Gerber viewer software. There are several free and paid Gerber viewers available, such as Gerbv, ViewMate, and CAM350. These viewers allow you to open and inspect the Gerber files, checking for any errors, missing features, or layer misalignments. It’s crucial to review the Gerber files before sending them to the manufacturer to avoid any issues during fabrication.

5. What should I do if I encounter problems during the Eagle to Gerber conversion process?
   If you face any issues while converting your Eagle .brd file to Gerber format, first double-check your CAM Processor settings and ensure that you have selected the correct layers and output directory. If the problem persists, consult the Eagle documentation or seek assistance from the Eagle community forums. You can also reach out to your PCB manufacturer for guidance, as they may have specific recommendations or requirements for Gerber file generation.

Conclusion

Converting Eagle .brd files to Gerber format is a critical step in the PCB manufacturing process. By following the guidelines outlined in this article, you can ensure that your PCB design is correctly translated into Gerber files that can be easily understood and processed by PCB fabrication machines. Remember to include all necessary layers, verify the Gerber output, and communicate with your manufacturer for any specific requirements or concerns.

By taking the time to properly convert your Eagle designs to Gerber format, you can streamline the PCB fabrication process, reduce the chances of errors, and ultimately achieve high-quality PCBs that meet your design specifications. With the right tools and attention to detail, converting Eagle .brd to Gerber can be a straightforward and reliable process.