Gerber files are the standard format used in the PCB (Printed Circuit Board) manufacturing industry to convey design information to fabrication houses. These files contain all the necessary data about the PCB layers, solder mask, silkscreen, drill holes, and more. Generating accurate Gerber files is a critical step in the PCB design process, as any errors can lead to manufacturing defects, delays, and increased costs. In this comprehensive guide, we will explore how to generate Gerber files using some of the most popular PCB design software tools, including Altium Designer, KiCad, Eagle, OrCAD, and PADS. We will also discuss best practices, common pitfalls, and tips to ensure your Gerber files are error-free.
1. What Are Gerber Files?
Overview of Gerber Files
Gerber files are a set of 2D binary vector images that represent each layer of a PCB. They were originally developed by Gerber Systems Corporation (now Ucamco) and have become the de facto standard for PCB manufacturing. Each Gerber file corresponds to a specific layer or feature of the PCB, such as:
- Copper layers (Top, Bottom, Inner)
- Solder mask layers
- Silkscreen layers
- Drill files (Excellon format)
- Board outline
Why Are Gerber Files Important?
Gerber files serve as the “blueprint” for PCB manufacturing. They provide the fabrication house with all the information needed to produce the physical board, including:
- The layout of traces and pads.
- The placement of components.
- The location of drill holes.
- The application of solder mask and silkscreen.
Accurate Gerber files are essential to ensure that the manufactured PCB matches the designer’s intent.
2. General Steps for Generating Gerber Files
While the exact process for generating Gerber files varies depending on the PCB design software, the general steps are as follows:
- Complete the PCB Design: Ensure that the PCB layout is finalized, with all components placed and routed.
- Configure Gerber Settings: Set up the Gerber file generation parameters, such as layer mapping, file format, and units.
- Generate Gerber Files: Export the Gerber files for each layer and feature.
- Generate Drill Files: Export the drill files (Excellon format) for hole drilling.
- Verify the Files: Use a Gerber viewer to inspect the files for accuracy and completeness.
- Package and Submit: Compress the Gerber and drill files into a single archive and submit them to the fabrication house.
3. Generating Gerber Files in Altium Designer
Step 1: Open the PCB Design
- Launch Altium Designer and open your PCB project.
Step 2: Access the Gerber Setup
- Go to File > Fabrication Outputs > Gerber Files.
Step 3: Configure Gerber Settings
- In the Gerber Setup dialog, configure the following:
- General Tab: Set the units (inches or millimeters) and format (2:5 for high precision).
- Layers Tab: Select the layers to include in the Gerber files (e.g., Top Copper, Bottom Copper, Solder Mask, Silkscreen).
- Drill Drawing Tab: Enable drill drawing and drill guide layers.
- Apertures Tab: Use embedded apertures (RS-274X format).
- Advanced Tab: Set the film size and zero suppression.
Step 4: Generate Gerber Files
- Click OK to generate the Gerber files. They will be saved in the specified output folder.
Step 5: Generate Drill Files
- Go to File > Fabrication Outputs > NC Drill Files.
- Configure the drill settings and click OK to generate the drill files.
Step 6: Verify the Files
- Use Altium’s built-in Gerber viewer or an external tool like GerberLogix or ViewMate to inspect the files.
4. Generating Gerber Files in KiCad
Step 1: Open the PCB Design
- Launch KiCad and open your PCB project in the PCB Editor.
Step 2: Access the Plot Dialog
- Go to File > Plot.
Step 3: Configure Gerber Settings
- In the Plot dialog, configure the following:
- Output Directory: Choose where to save the Gerber files.
- Layers: Select the layers to include (e.g., F.Cu, B.Cu, F.Mask, B.Mask, F.SilkS, B.SilkS).
- Options: Enable “Use Protel filename extensions” and “Exclude PCB edge layer from other layers.”
- Plot Format: Select Gerber (RS-274X).
Step 4: Generate Gerber Files
- Click Plot to generate the Gerber files.
Step 5: Generate Drill Files
- Go to File > Fabrication Outputs > Drill Files.
- Configure the drill settings and click Generate Drill File.
Step 6: Verify the Files
- Use KiCad’s Gerber Viewer or an external tool to inspect the files.
5. Generating Gerber Files in Eagle
Step 1: Open the PCB Design
- Launch Eagle and open your PCB project.
Step 2: Access the CAM Processor
- Go to File > CAM Processor.
Step 3: Configure Gerber Settings
- In the CAM Processor, load a Gerber configuration file (e.g., gerb274x.cam) or create a new job.
- Add the following layers:
- Top Copper: Top (1)
- Bottom Copper: Bottom (16)
- Top Solder Mask: tStop (29)
- Bottom Solder Mask: bStop (30)
- Top Silkscreen: tPlace (21)
- Bottom Silkscreen: bPlace (22)
- Board Outline: Dimension (20)
Step 4: Generate Gerber Files
- Click Process Job to generate the Gerber files.
Step 5: Generate Drill Files
- Add a drill layer to the CAM job and configure the settings.
- Click Process Job to generate the drill files.
Step 6: Verify the Files
- Use Eagle’s CAM Viewer or an external tool to inspect the files.
6. Generating Gerber Files in OrCAD
Step 1: Open the PCB Design
- Launch OrCAD and open your PCB project.
Step 2: Access the Artwork Control Form
- Go to Manufacture > Artwork.
Step 3: Configure Gerber Settings
- In the Artwork Control Form, configure the following:
- Film Control: Add the layers to include (e.g., TOP, BOTTOM, SOLDERMASK_TOP, SOLDERMASK_BOTTOM, SILKSCREEN_TOP, SILKSCREEN_BOTTOM).
- General Parameters: Set the format (RS-274X) and units (inches or millimeters).
Step 4: Generate Gerber Files
- Click Create Artwork to generate the Gerber files.
Step 5: Generate Drill Files
- Go to Manufacture > NC > NC Drill.
- Configure the drill settings and click Drill to generate the drill files.
Step 6: Verify the Files
- Use OrCAD’s Gerber Viewer or an external tool to inspect the files.
7. Generating Gerber Files in PADS
Step 1: Open the PCB Design
- Launch PADS and open your PCB project.
Step 2: Access the CAM Document
- Go to File > CAM.
Step 3: Configure Gerber Settings
- In the CAM Document, add the following layers:
- Top Copper: Top (Top Layer)
- Bottom Copper: Bottom (Bottom Layer)
- Top Solder Mask: Solder Mask Top
- Bottom Solder Mask: Solder Mask Bottom
- Top Silkscreen: Silkscreen Top
- Bottom Silkscreen: Silkscreen Bottom
- Board Outline: Board Outline
Step 4: Generate Gerber Files
- Click Run to generate the Gerber files.
Step 5: Generate Drill Files
- Add a drill layer to the CAM document and configure the settings.
- Click Run to generate the drill files.
Step 6: Verify the Files
- Use PADS’ CAM Viewer or an external tool to inspect the files.
8. Best Practices for Generating Gerber Files
1. Double-Check Layer Mapping
Ensure that the correct layers are included in the Gerber files and that they are mapped accurately.
2. Use RS-274X Format
The RS-274X format (extended Gerber) is the most widely accepted and includes embedded apertures, reducing the risk of errors.
3. Include a Readme File
Provide a readme file that lists all the Gerber and drill files, along with a brief description of each.
4. Verify with a Gerber Viewer
Always inspect the Gerber files using a Gerber viewer to ensure accuracy and completeness.
5. Communicate with Your Fabricator
Consult with your PCB manufacturer to confirm their specific requirements for Gerber files.
9. Common Pitfalls and How to Avoid Them
1. Missing Layers
Double-check that all required layers (e.g., solder mask, silkscreen) are included in the Gerber files.
2. Incorrect Units or Format
Ensure that the units (inches or millimeters) and format (RS-274X) are consistent across all files.
3. Overlapping Features
Avoid overlapping features (e.g., traces and pads) that could cause manufacturing issues.
4. Incomplete Drill Files
Verify that the drill files include all hole sizes and locations.
10. Conclusion
Generating accurate Gerber files is a critical step in the PCB design process, ensuring that your design is faithfully reproduced during manufacturing. By following the step-by-step instructions for popular PCB design software tools like Altium Designer, KiCad, Eagle, OrCAD, and PADS, you can create error-free Gerber files that meet the requirements of your fabrication house. Remember to verify your files with a Gerber viewer and communicate with your manufacturer to avoid common pitfalls. With careful attention to detail and adherence to best practices, you can streamline the PCB manufacturing process and bring your designs to life with confidence.
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