How to Generate Gerber Files based on Different PCB Design Software

How to Generate Gerber Files based on Different PCB Design Software

Introduction

In the world of printed circuit board (PCB) design and manufacturing, Gerber files play a crucial role as the universal language between designers and fabricators. These files contain all the necessary information for PCB manufacturers to produce your board accurately. However, the process of generating Gerber files can vary depending on the PCB design software you're using.

This comprehensive guide will walk you through the process of generating Gerber files using various popular PCB design software packages. We'll cover the step-by-step procedures, best practices, and common pitfalls to avoid. Whether you're a seasoned PCB designer or just starting out, this article will provide valuable insights to ensure your designs are accurately translated into manufacturable boards.

Let's dive into the world of Gerber file generation and explore how different PCB design software handles this critical step in the PCB production process.

Understanding Gerber Files

What are Gerber Files?

Before we delve into the specifics of generating Gerber files with different software, it's essential to understand what Gerber files are and why they're important.

Definition

Gerber files are a set of computer-aided design (CAD) files that contain information about the different layers and features of a PCB. They serve as the standard format for communicating PCB design information to manufacturers.

Types of Gerber Files

A complete set of Gerber files typically includes:

1. Copper layers (e.g., top layer, bottom layer, inner layers)
2. Solder mask layers
3. Silkscreen layers
4. Drill files
5. Board outline

Importance of Gerber Files

Gerber files are critical because they:

1. Provide a universal format understood by all PCB manufacturers
2. Contain precise information about PCB features and dimensions
3. Allow for accurate quoting and manufacturing of PCBs

Gerber File Formats

There are two main Gerber file formats in use:

1. RS-274X (Extended Gerber): The most common and recommended format
2. RS-274D: An older format, less commonly used today

Most modern PCB design software generates RS-274X format files by default.

General Steps for Generating Gerber Files

While the specific process varies between software packages, the general steps for generating Gerber files are as follows:

1. Complete your PCB design
2. Configure Gerber output settings
3. Select layers to export
4. Choose file naming conventions
5. Set resolution and units
6. Generate and save Gerber files
7. Verify the generated files

Now, let's explore how to generate Gerber files using different PCB design software packages.

Generating Gerber Files in Altium Designer

Altium Designer is a popular PCB design software known for its powerful features and comprehensive design environment.

Steps to Generate Gerber Files in Altium Designer

1. Open your PCB project in Altium Designer
2. Go to "File" > "Fabrication Outputs" > "Gerber Files"
3. In the "Gerber Setup" dialog: Select the layers you want to export Choose the Gerber format (X2 format is recommended) Set the units and precision
4. Click "OK" to generate the files
5. Choose a destination folder and click "OK" to save the files

Best Practices for Altium Designer

• Use the "CAMtastic" tool to review your Gerber files before sending them to the manufacturer
• Enable the "Append .gbr extension" option for easier file identification
• Use the "Gerber X2" format for additional metadata support

Generating Gerber Files in Eagle

Eagle, now part of Autodesk, is another widely used PCB design software, especially popular among hobbyists and small businesses.

Steps to Generate Gerber Files in Eagle

1. Open your board layout in Eagle
2. Click on the "CAM Processor" icon or go to "File" > "CAM Processor"
3. In the CAM Processor window: Load a predefined CAM job or create a new one Select the layers to export Set the output directory
4. Click "Process Job" to generate the Gerber files

Best Practices for Eagle

• Use the "gerb274x.cam" job file for RS-274X format output
• Verify that all necessary layers are included in the CAM job
• Double-check the drill file generation settings

Generating Gerber Files in KiCad

KiCad is a popular open-source PCB design software that has gained significant traction in recent years.

Steps to Generate Gerber Files in KiCad

1. Open your PCB layout in KiCad's PCB Editor
2. Go to "File" > "Plot"
3. In the "Plot" dialog: Select the layers to export Choose the output directory Set the output format to "Gerber"
4. Click "Plot" to generate the Gerber files
5. Click on "Generate Drill Files" to create the drill file

Best Practices for KiCad

• Use the "Use Protel filename extensions" option for compatibility
• Enable "Use Auxiliary Axis as origin" for consistent positioning
• Review the generated files using GerbView (included with KiCad)

Generating Gerber Files in OrCAD

OrCAD, part of the Cadence suite of tools, is a professional-grade PCB design software used in many industries.

Steps to Generate Gerber Files in OrCAD

1. Open your PCB design in OrCAD PCB Editor
2. Go to "Manufacture" > "Artwork"
3. In the "Artwork Control Form": Select the layers to plot Set the output to "Gerber 274X" Configure film options and scaling
4. Click "OK" to generate the Gerber files

Best Practices for OrCAD

• Use the "Aperture List" command to verify aperture definitions
• Enable "Suppress unconnected internal pads" to reduce file size
• Use the "Null pad suppression" option for cleaner output

Generating Gerber Files in PADS

PADS, now part of Siemens EDA (formerly Mentor Graphics), is another professional PCB design tool used in various industries.

Steps to Generate Gerber Files in PADS

1. Open your PCB layout in PADS Layout
2. Go to "Output" > "CAM"
3. In the CAM setup dialog: Select "Gerber" as the output type Choose the layers to output Set the output directory
4. Click "OK" to generate the Gerber files

Best Practices for PADS

• Use the "CAM Setup Wizard" for guided Gerber file generation
• Enable "Embedded Apertures" for RS-274X compatibility
• Verify the drill file format (Excellon is commonly used)

Comparison of Gerber Generation Features

Here's a comparison table of Gerber file generation features across different PCB design software:

Best Practices for Gerber File Generation

Regardless of the software you're using, here are some universal best practices for generating Gerber files:

File Naming Conventions

• Use clear, consistent naming conventions for your Gerber files
• Include the layer name and function in the filename
• Avoid spaces and special characters in filenames

Layer Selection

• Ensure all necessary layers are included in the Gerber output
• Double-check that drill files are generated correctly
• Include the board outline in your Gerber set

Resolution and Units

• Use a high resolution (e.g., 1/10000 inch or 0.1 mil) for accuracy
• Stick to a single unit system (imperial or metric) throughout the process

Aperture and Drill Tools

• Verify that all required apertures are defined
• Check that drill sizes match your design specifications

File Verification

• Always review your Gerber files using a Gerber viewer before submission
• Check for common issues like missing pads, incorrect board outlines, or misaligned layers

Common Pitfalls and How to Avoid Them

When generating Gerber files, be aware of these common issues:

1. Missing layers: Always double-check that all required layers are included in your Gerber set
2. Incorrect scale or units: Ensure your Gerber settings match your design units
3. Misaligned drill files: Verify that drill file coordinates align with your Gerber layers
4. Undefined apertures: Make sure all necessary apertures are defined in your output
5. Incomplete board outlines: Check that the board outline is complete and properly defined

To avoid these issues:

• Use predefined Gerber output configurations when available
• Implement a checklist for Gerber file generation and verification
• Regularly update your PCB design software to benefit from bug fixes and improvements

Verifying Gerber Files

After generating your Gerber files, it's crucial to verify them before sending them to the manufacturer. Here are some steps to follow:

1. Use a Gerber viewer: Many PCB design software packages include built-in Gerber viewers Free options like gerbv or online viewers are also available
2. Check each layer individually: Verify that all expected features are present Look for any unexpected artifacts or errors
3. Overlay multiple layers: Check for proper alignment between layers Verify that vias and pads align correctly across layers
4. Review the drill file: Ensure all holes are present and correctly sized Check that hole positions match your design
5. Verify the board outline: Confirm that the board shape matches your design Check for any gaps or inconsistencies in the outline
6. Compare with your original design: Cross-reference the Gerber files with your PCB layout Verify dimensions and feature positions

Frequently Asked Questions (FAQ)

Q1: What's the difference between Gerber X and Gerber X2 formats?

A1: Gerber X (RS-274X) and Gerber X2 are both extended Gerber formats, but Gerber X2 offers some additional features:

1. Gerber X (RS-274X): Industry standard format Includes aperture definitions within the file Supports most PCB manufacturing requirements
2. Gerber X2: Newer format, backward compatible with Gerber X Includes additional metadata (e.g., layer function, part number) Supports more efficient machine reading and processing Allows for easier automation in the PCB manufacturing process

Most PCB manufacturers accept both formats, but Gerber X2 can provide additional clarity and automation in the manufacturing process.

Q2: Do I need to generate separate files for the drill data, or is it included in the Gerber files?

A2: Typically, drill data is generated as a separate file from the Gerber files:

1. Gerber files: Contain information about the PCB layers (copper, solder mask, silkscreen, etc.)
2. Drill files: Usually in Excellon format, contain information about hole locations and sizes

When sending files to a PCB manufacturer, you generally need to provide both:

• A set of Gerber files for the PCB layers
• A drill file (or files) for the hole information

Some newer formats, like ODB++, can include both layer and drill information in a single file set, but this is not as universally accepted as the combination of Gerber and Excellon files.

Q3: How can I ensure that my Gerber files will be interpreted correctly by the PCB manufacturer?

A3: To ensure your Gerber files are interpreted correctly:

1. Use standard file formats: RS-274X for Gerber files Excellon format for drill files
2. Include a readme file with your Gerber set: List all included files and their corresponding layers Specify units (imperial or metric) and resolution used
3. Follow naming conventions: Use clear, descriptive names for each file Include layer information in the filename (e.g., "BoardName_TopCopper.gbr")
4. Verify your files: Use a Gerber viewer to check all layers before submission Compare the viewer output with your original design
5. Communicate with your manufacturer: Provide any special instructions or requirements Be available to answer questions about your design
6. Use a Gerber X2 format if supported by both your software and manufacturer: Provides additional metadata for clearer interpretation
7. Consider using a Design for Manufacturing (DFM) check service: Many manufacturers offer this service to catch potential issues before production

By following these steps, you can significantly increase the likelihood that your Gerber files will be interpreted correctly by the PCB manufacturer.

Q4: How do I handle non-plated holes in my Gerber and drill files?

A4: Handling non-plated holes requires attention in both your PCB design software and when generating Gerber and drill files:

1. In your PCB design software: Designate holes as non-plated during the design process Use a different pad class or hole property for non-plated holes
2. When generating Gerber files: Ensure that non-plated holes are not included in the copper layer Gerber files They should appear in the drill file and potentially in the board outline Gerber
3. For the drill file: Most software will generate separate drill files for plated and non-plated holes Alternatively, a single drill file may use different tool numbers for plated and non-plated holes
4. In your documentation: Clearly indicate which drill file or tool numbers correspond to non-plated holes Include this information in your readme file or fabrication notes
5. Verify in a Gerber viewer: Check that non-plated holes appear correctly (i.e., no copper pads on layers) Ensure they are present in the drill file visualization
6. Communicate with your manufacturer: Explicitly mention the presence of non-plated holes in your design Verify their preferred method for specifying non-plated holes

By carefully managing non-plated holes throughout the design and file generation process, you can ensure they are correctly manufactured in your PCB.

Q5: What should I do if my PCB design software doesn't support direct Gerber file generation?

A5: If your PCB design software doesn't support direct Gerber file generation, you have several options:

1. Use an intermediate file format: Export your design to a universal format like DXF or IPC-2581 Use a Gerber conversion tool to generate Gerber files from this format
2. Third-party Gerber generation tools: Some standalone software can generate Gerber files from various PCB design formats Examples include GerbTool or CAM350
3. Online Gerber file generators: Some websites offer services to convert PCB designs to Gerber files Be cautious with confidential designs when using online services
4. Upgrade your software: Consider switching to a PCB design software that supports Gerber generation Many free or low-cost options (like KiCad) offer this feature
5. Manual generation (not recommended for complex boards): Export each layer as a vector graphic Manually create Gerber files following the RS-274X specification
6. Consult with your PCB manufacturer: Some manufacturers can work with alternative file formats They may offer services to convert your files to Gerber format

Remember, accurate Gerber files are crucial for successful PCB manufacturing. If your current software doesn't support Gerber generation, it's often worth investing in a solution that does, especially for complex or production-level designs.