How to Export Gerber Files from Eagle CAD: A Complete Step-by-Step Guide

 

Introduction

Exporting Gerber files from Eagle CAD is a crucial step in the PCB manufacturing process. Gerber files serve as the industry-standard format for communicating PCB design information to fabrication houses, containing all the necessary data for manufacturing your printed circuit board. This comprehensive guide will walk you through the entire process of generating high-quality Gerber files from your Eagle PCB designs, ensuring your boards are manufactured exactly as intended.

Whether you're a beginner just starting with PCB design or an experienced engineer looking to refine your workflow, understanding how to properly export Gerber files from Eagle is essential for successful PCB manufacturing. The process involves several critical steps, from initial setup and configuration to final file verification, each requiring attention to detail to ensure manufacturing accuracy.

Understanding Gerber Files and Their Importance

What Are Gerber Files?

Gerber files, also known as RS-274X files, are the de facto standard for PCB fabrication data exchange. These files contain precise geometric information that describes the copper traces, drill holes, solder mask, and other essential elements of your PCB design. Named after the Gerber Scientific Instrument Company that developed the format, these files serve as the blueprint that PCB manufacturers use to create your physical circuit boards.

Why Proper Gerber Export Matters

The quality and accuracy of your Gerber files directly impact the final manufactured PCB. Incorrect or incomplete Gerber files can result in manufacturing delays, increased costs, or even unusable boards. Common issues that arise from improper Gerber export include:

• Missing or incorrect drill files
• Improper layer mapping
• Incorrect aperture definitions
• Missing solder mask or silkscreen layers
• Scaling issues
• File format incompatibilities

By following proper export procedures, you can avoid these costly mistakes and ensure your PCBs are manufactured correctly the first time.

Prerequisites and Setup

Eagle CAD Version Requirements

Before beginning the Gerber export process, ensure you have a compatible version of Eagle CAD installed. While the basic export functionality has remained consistent across versions, newer versions offer improved CAM processor capabilities and better compatibility with modern PCB manufacturers.

Eagle Version
Key Features for Gerber Export
Eagle 9.x
Enhanced CAM processor, improved drill file generation
Eagle 8.x
Stable CAM jobs, reliable Gerber output
Eagle 7.x
Basic Gerber export functionality
Eagle 6.x and below
Limited features, may require manual configuration

Essential Files and Components

Before starting the export process, verify that your Eagle project contains all necessary components:

1. Board file (.brd) - Your completed PCB layout
2. Schematic file (.sch) - Associated schematic (for cross-reference)
3. Library files (.lbr) - All custom libraries used in the design
4. Design rule check (DRC) - Completed and passed
5. Electrical rule check (ERC) - Completed and passed

PCB Design Verification Checklist

Verification Item
Status
Notes
All components placed
☐
Check for missing or unplaced parts
Routing completed
☐
Verify 100% routing completion
DRC passed
☐
No violations remaining
Layer stackup defined
☐
Correct number and type of layers
Board outline defined
☐
Clear board boundaries
Via specifications set
☐
Proper via sizes and drill specs
Text and silkscreen readable
☐
Minimum text size requirements met

Step-by-Step Gerber Export Process

Step 1: Opening the CAM Processor

The CAM (Computer Aided Manufacturing) processor in Eagle is the primary tool for generating Gerber files. To access it:

1. Open your completed board file (.brd) in Eagle
2. Navigate to the File menu
3. Select "CAM Processor" or use the keyboard shortcut (typically Ctrl+Shift+C)
4. The CAM Processor window will open, displaying the job configuration interface

Step 2: Loading the Appropriate CAM Job

Eagle comes with several pre-configured CAM jobs for different PCB manufacturers and stackups. The most commonly used configurations include:

Standard CAM Jobs:

• gerb274x.cam - Standard 2-layer boards
• gerb274x-4layer.cam - 4-layer boards
• excellon.cam - Drill file generation
• gerber-excellon.cam - Combined Gerber and drill files

To load a CAM job:

1. Click the "Load job file" button in the CAM Processor
2. Navigate to the Eagle installation directory (typically in the cam folder)
3. Select the appropriate .cam file for your board configuration
4. The job will load with predefined layer assignments and settings

Step 3: Configuring Layer Assignments

Proper layer assignment is critical for accurate Gerber generation. Each layer in your Eagle design must be mapped to the correct manufacturing layer. Here's how to configure them:

2-Layer Board Configuration

Eagle Layer
Gerber Layer
File Extension
Purpose
Top (1)
Top Copper
.GTL
Top copper traces
Bottom (16)
Bottom Copper
.GBL
Bottom copper traces
tStop (29)
Top Solder Mask
.GTS
Top solder mask openings
bStop (30)
Bottom Solder Mask
.GBS
Bottom solder mask openings
tPlace (21)
Top Silkscreen
.GTO
Top silkscreen/legend
bPlace (22)
Bottom Silkscreen
.GBO
Bottom silkscreen/legend
Dimension (20)
Board Outline
.GKO
Mechanical outline

4-Layer Board Configuration

Eagle Layer
Gerber Layer
File Extension
Purpose
Top (1)
Top Copper
.GTL
Top copper traces
Route2 (2)
Inner Layer 1
.G1
Internal copper layer 1
Route15 (15)
Inner Layer 2
.G2
Internal copper layer 2
Bottom (16)
Bottom Copper
.GBL
Bottom copper traces
tStop (29)
Top Solder Mask
.GTS
Top solder mask
bStop (30)
Bottom Solder Mask
.GBS
Bottom solder mask
tPlace (21)
Top Silkscreen
.GTO
Top silkscreen
bPlace (22)
Bottom Silkscreen
.GBO
Bottom silkscreen
Dimension (20)
Board Outline
.GKO
Board outline

Step 4: Setting Output Directories and File Names

Organizing your Gerber files properly is essential for manufacturing submission:

1. Create a dedicated output folder for your Gerber files
2. Use consistent naming conventions that match your PCB manufacturer's requirements
3. Include revision information in folder or file names
4. Separate drill files from Gerber files if required by your manufacturer

Recommended folder structure:

ProjectName_Rev1.0_Gerbers/

├── Gerbers/
│   ├── ProjectName.GTL
│   ├── ProjectName.GBL
│   ├── ProjectName.GTS
│   └── ... (other Gerber files)
├── Drill/
│   └── ProjectName.TXT
└── README.txt

Step 5: Configuring Advanced Settings

Aperture Settings

Proper aperture configuration ensures accurate trace widths and pad sizes:

1. Use RS-274X format for embedded aperture definitions
2. Set minimum aperture size to match your manufacturer's capabilities
3. Enable aperture optimization to reduce file size
4. Verify aperture list completeness before export

Coordinate Format and Units

Setting
Recommended Value
Reason
Coordinate Format
2.4 (Imperial) or 3.3 (Metric)
Industry standard precision
Units
Inches or Millimeters
Match your design units
Leading Zero Suppression
Yes
Reduces file size
Trailing Zero Suppression
No
Maintains precision

Output Resolution

Set appropriate resolution based on your PCB complexity:

• Standard PCBs: 0.1 mil (2.54 microns)
• High-density PCBs: 0.01 mil (0.254 microns)
• RF/Microwave PCBs: 0.001 mil (0.0254 microns)

Step 6: Generating Drill Files

Drill files require special attention as they define hole sizes and locations:

Excellon Drill File Configuration

Parameter
Setting
Notes
Format
Excellon
Industry standard
Units
Match Gerber files
Consistency is key
Zero Suppression
Leading
Standard practice
Coordinate Format
2.4 or 3.3
Match Gerber precision
Tool List
Embedded
Include tool definitions

Drill File Contents Verification

Ensure your drill files include:

• Through-hole component pins
• Via drill holes
• Mounting holes
• Tooling holes (if applicable)
• Proper tool size definitions

Step 7: Running the Export Process

Once all settings are configured:

1. Review all job settings one final time
2. Select the output directory
3. Click "Process Job" to begin export
4. Monitor the progress and watch for any error messages
5. Verify file generation in the output directory

Common export errors and solutions:

Error Message
Cause
Solution
"Layer not found"
Missing layer assignment
Verify layer mapping
"Invalid aperture"
Aperture definition error
Check aperture settings
"File write error"
Permission or path issue
Check output directory
"Drill size conflict"
Multiple drill sizes for same hole
Review drill specifications

Advanced Configuration Options

Custom CAM Job Creation

For specialized requirements, you may need to create custom CAM jobs:

Creating a New CAM Job

1. Start with a base configuration closest to your needs
2. Add or remove sections as required
3. Modify layer assignments for your specific stackup
4. Adjust device settings for output format requirements
5. Save the job file with a descriptive name

CAM Job Best Practices

Best Practice
Benefit
Document all modifications
Easier troubleshooting and reuse
Test with simple designs first
Validate configuration before complex boards
Version control CAM jobs
Track changes and improvements
Share standardized jobs
Consistency across team projects
Regular validation
Ensure continued compatibility

Specialized Layer Configurations

High-Layer Count Boards

For boards with more than 4 layers:

1. Map each signal layer to appropriate Gerber layers
2. Include power and ground planes as separate files
3. Verify layer stack symmetry for manufacturing
4. Document layer purposes clearly

Flexible PCB Considerations

Flexible PCB Gerber export requires additional considerations:

• Coverlay layers for flexible sections
• Stiffener definitions for rigid sections
• Bend radius specifications in documentation
• Material stackup variations across the board

Manufacturer-Specific Requirements

Different PCB manufacturers may have specific requirements for Gerber files:

Common Manufacturer Variations

Manufacturer Type
Typical Requirements
Low-cost Asian fabs
Standard RS-274X, Excellon drill
US/European fabs
May require specific naming conventions
Prototype services
Often accept standard formats
High-reliability fabs
Strict format requirements, additional docs

Quality Assurance and File Verification

Pre-Submission Verification Steps

Before submitting your Gerber files to a manufacturer, perform these verification steps:

Visual Inspection Checklist

Item
Verification
Status
Layer registration
All layers align properly
☐
Trace widths
Match design specifications
☐
Pad sizes
Correct for component footprints
☐
Via sizes
Appropriate for current requirements
☐
Silkscreen clarity
Text readable, no overlaps
☐
Solder mask openings
Proper clearances maintained
☐
Board outline
Clean, closed boundary
☐

File Completeness Check

Verify all necessary files are present:

Standard 2-layer board files:

• Top copper (.GTL)
• Bottom copper (.GBL)
• Top solder mask (.GTS)
• Bottom solder mask (.GBS)
• Top silkscreen (.GTO)
• Bottom silkscreen (.GBO)
• Board outline (.GKO)
• Drill file (.TXT or .DRL)

Using Gerber Viewers for Verification

Gerber viewer software helps verify file accuracy:

Recommended Gerber Viewers

Viewer
Type
Key Features
GC-Prevue
Free
Basic viewing, layer management
CAMtastic
Professional
Advanced analysis, DFM checks
Gerbv
Open source
Multi-platform, good for Linux
Online viewers
Web-based
Quick verification, no installation

Verification Process with Viewers

1. Load all Gerber files into the viewer
2. Check layer alignment by toggling visibility
3. Verify drill file overlay with copper layers
4. Inspect critical areas at high magnification
5. Generate reports if available in the viewer

Common Issues and Solutions

File Generation Problems

Problem
Symptoms
Solution
Missing layers
Incomplete Gerber set
Review CAM job layer assignments
Incorrect scaling
Size mismatches
Verify units and coordinate format
Drill alignment issues
Holes don't match pads
Check drill file origin settings
Aperture problems
Incorrect trace widths
Review aperture definitions

Manufacturing Compatibility Issues

Address potential manufacturing problems:

1. Minimum trace width violations - Adjust design or manufacturer
2. Drill size limitations - Verify manufacturer capabilities
3. Aspect ratio concerns - Check hole depth vs. diameter
4. Solder mask sliver issues - Review mask clearances

Best Practices for Different Board Types

Simple 2-Layer Boards

For basic 2-layer designs:

Simplified Workflow

1. Use standard Eagle CAM jobs
2. Minimal customization required
3. Standard file naming conventions
4. Basic verification sufficient

Key Considerations

• Trace width consistency
• Via size standardization
• Component clearances
• Silkscreen readability

Complex Multi-Layer Boards

Multi-layer designs require additional attention:

Extended Verification Process

Layer Type
Specific Checks
Signal layers
Impedance control requirements
Power planes
Proper plane connections
Ground planes
Continuous ground references
Internal layers
Proper isolation and clearances

Documentation Requirements

Multi-layer boards need comprehensive documentation:

• Layer stackup specifications
• Impedance requirements
• Material specifications
• Drill charts with finish requirements

High-Frequency and RF Boards

RF designs have unique Gerber export considerations:

Special Requirements

1. Precise dimensional control - Tighter tolerances
2. Controlled impedance specifications - Detailed documentation
3. Material considerations - Specific substrate requirements
4. Via stitching requirements - Ground plane connections

Prototype vs. Production Exports

Different export strategies for different stages:

Prototype Board Exports

Focus Area
Approach
Speed
Use standard CAM jobs
Cost
Minimize complexity
Testing
Include test points clearly
Modifications
Design for easy changes

Production Board Exports

Focus Area
Approach
Reliability
Thorough verification process
Manufacturing
Optimize for volume production
Documentation
Complete fabrication packages
Quality
Strict adherence to specifications

Troubleshooting Common Export Problems

File Generation Errors

CAM Processor Error Messages

When the CAM processor encounters problems, it typically displays specific error messages:

"Layer not assigned" errors:

• Cause: Layer mapping incomplete or incorrect
• Solution: Review and complete all layer assignments
• Prevention: Use pre-configured CAM jobs when possible

"Invalid file path" errors:

• Cause: Output directory doesn't exist or lacks permissions
• Solution: Create directory and verify write permissions
• Prevention: Always test output paths before processing

"Aperture definition errors":

• Cause: Conflicting or invalid aperture specifications
• Solution: Reset aperture settings to defaults
• Prevention: Use standard aperture configurations

File Quality Issues

Gerber File Corruption

Signs of corrupted Gerber files and solutions:

Symptom
Likely Cause
Resolution
Files won't open in viewers
Format corruption
Re-export with different settings
Missing features in viewer
Incomplete export
Verify all layers processed
Scaling problems
Unit conversion errors
Check coordinate format settings
Garbled text/symbols
Character encoding issues
Use standard ASCII characters only

Drill File Problems

Drill files are particularly prone to issues:

Common drill file problems:

1. Duplicate tool definitions - Clean up tool list
2. Missing holes - Verify all drill layers included
3. Incorrect hole sizes - Check design rules and library definitions
4. Position accuracy errors - Verify coordinate format consistency

Manufacturing Feedback Issues

DFM (Design for Manufacturing) Violations

When manufacturers report DFM issues with your Gerber files:

Issue Type
Common Causes
Solutions
Trace width violations
Design rules not matching fab capabilities
Update design rules or change manufacturer
Drill size issues
Non-standard drill sizes used
Standardize on manufacturer-supported sizes
Solder mask problems
Insufficient clearances
Increase mask expansion settings
Silkscreen conflicts
Text over pads or vias
Relocate or remove conflicting text

Communication with Manufacturers

Effective communication strategies:

1. Provide complete file sets - Don't make manufacturers guess
2. Include clear documentation - Specifications and requirements
3. Respond quickly to questions - Manufacturing delays are costly
4. Maintain version control - Track changes and revisions clearly

Advanced Gerber Export Techniques

Panelization Considerations

When creating panels for manufacturing efficiency:

Panel Design Requirements

Aspect
Consideration
Board spacing
Manufacturer routing capabilities
Tab locations
Mechanical stress distribution
Tooling holes
Registration and handling
V-scoring
Alternative to tab routing
Fiducial markers
Placement accuracy

Panel Gerber Export

Panelized designs require special export considerations:

1. Include panel outline in mechanical layers
2. Add tooling and fiducial markers to appropriate layers
3. Verify tab and scoring definitions are clear
4. Document depaneling instructions clearly

Embedded Components and Advanced Features

Modern PCB designs often include advanced features:

Buried and Blind Vias

For designs using buried or blind vias:

1. Define via types clearly in drill files
2. Include start and stop layer information
3. Verify manufacturer capabilities before design
4. Document via specifications thoroughly

Component Embedding

For embedded component designs:

Consideration
Implementation
Cavity definitions
Special mechanical layers
Component outlines
Clear boundary definitions
Assembly drawings
Detailed component placement
Manufacturing notes
Special handling requirements

Automated Export Workflows

Script-Based Export

For repetitive tasks, consider automation:

1. Eagle ULP (User Language Programs) for custom export scripts
2. Batch processing for multiple board variants
3. Version control integration for automated builds
4. Quality check automation using script-driven viewers

Integration with Manufacturing Systems

Advanced workflows can integrate directly with manufacturing systems:

• Direct manufacturer portal uploads
• Automated DFM checking
• Real-time pricing and lead time feedback
• Order tracking and status updates

Industry Standards and Compliance

Gerber Format Standards

Understanding the standards ensures compatibility:

RS-274X Standard

The current Gerber standard includes:

• Aperture definitions embedded in files
• Coordinate data with specified precision
• Layer polarity and step-and-repeat information
• Attribute data for enhanced manufacturing information

IPC Standards Compliance

Relevant IPC standards for PCB manufacturing:

Standard
Title
Relevance
IPC-2221
Generic Standard on Printed Board Design
Design rules and guidelines
IPC-2222
Sectional Design Standard for Rigid PCBs
Specific rigid board requirements
IPC-6012
Qualification and Performance Specification
Manufacturing quality standards
IPC-A-600
Acceptability of Printed Boards
Visual acceptance criteria

Quality and Certification Requirements

ISO 9001 and Manufacturing Quality

For high-reliability applications:

1. Traceability requirements - File version control
2. Change management - Documented revision processes
3. Supplier qualification - Verified manufacturer capabilities
4. Quality records - Documentation of all processes

Industry-Specific Requirements

Different industries have specific requirements:

Automotive (ISO/TS 16949):

• Enhanced traceability
• PPAP documentation requirements
• Long-term availability guarantees

Medical (ISO 13485):

• Risk management documentation
• Biocompatibility considerations
• Regulatory submission requirements

Aerospace (AS9100):

• Material traceability
• First article inspection requirements
• Configuration management

Future Trends and Considerations

Emerging Technologies

Industry 4.0 and Smart Manufacturing

Modern PCB manufacturing is evolving:

• Digital twin integration - Virtual manufacturing simulation
• Real-time monitoring - Process feedback and optimization
• Artificial intelligence - Automated DFM optimization
• Blockchain tracking - Enhanced traceability and security

New File Formats and Standards

Evolution beyond traditional Gerber:

• ODB++ - More comprehensive data format
• IPC-2581 - Industry standard for manufacturing data
• Gerber X3 - Enhanced Gerber with embedded metadata
• Direct CAD integration - Elimination of intermediate formats

Design Tool Evolution

Eagle's Future Development

As Eagle continues to evolve:

1. Enhanced CAM capabilities
2. Improved manufacturer integration
3. Advanced verification tools
4. Cloud-based processing

Alternative Export Methods

New approaches to manufacturing data:

• API-based exports - Direct manufacturer integration
• Cloud processing - Remote file generation and verification
• AI-assisted optimization - Automatic DFM improvement
• Collaborative platforms - Real-time designer-manufacturer communication

Frequently Asked Questions (FAQ)

Q1: What file formats do I need to provide to PCB manufacturers?

Answer: For most PCB manufacturers, you need to provide a complete set of Gerber files along with drill files. The standard file set includes:

• Copper layers (GTL for top, GBL for bottom, and G1, G2, etc. for internal layers)
• Solder mask layers (GTS for top, GBS for bottom)
• Silkscreen layers (GTO for top, GBO for bottom)
• Board outline (GKO or mechanical layer)
• Drill files (TXT or DRL format with tool list)

Some manufacturers also accept Eagle's native board files (.brd), but Gerber files ensure maximum compatibility and reduce the risk of interpretation errors.

Q2: Why are my drill holes not aligning with the pads in the manufactured PCB?

Answer: Drill hole misalignment typically occurs due to coordinate system or origin point differences between the Gerber files and drill files. This problem usually stems from:

• Different origin points set for Gerber and drill file generation
• Coordinate format mismatches between files
• Unit conversion errors (mixing metric and imperial units)
• CAM job configuration errors in the layer-to-file mapping

To fix this, ensure all files use the same coordinate system, origin point, and units. Always verify alignment using a Gerber viewer before submitting files to the manufacturer.

Q3: How do I know if my Gerber files are compatible with my chosen PCB manufacturer?

Answer: Most reputable PCB manufacturers provide detailed specifications for acceptable file formats and design rules. To ensure compatibility:

1. Download the manufacturer's design rules and import them into Eagle
2. Run a DRC (Design Rule Check) to verify compliance
3. Check their CAM job requirements - many provide Eagle-specific CAM jobs
4. Use their online DFM tools if available for automated checking
5. Submit for quote review - most manufacturers will flag issues during the quote process

When in doubt, contact the manufacturer's technical support team with specific questions about your design requirements.

Q4: Should I include a README file with my Gerber submission, and what should it contain?

Answer: Yes, including a comprehensive README file significantly reduces manufacturing confusion and potential errors. Your README file should contain:

• Board specifications (thickness, layer count, material requirements)
• File list and descriptions (what each Gerber file represents)
• Design rules used (minimum trace width, via sizes, drill specifications)
• Special requirements (impedance control, surface finish, color preferences)
• Quantity and delivery requirements
• Contact information for technical questions

This documentation helps manufacturers understand your intent and catch potential issues before production begins.

Q5: Can I use the same CAM job settings for all my Eagle PCB designs?

Answer: While you can use the same CAM job for boards with similar characteristics, it's not recommended for all designs. Different PCB types require different configurations:

• 2-layer vs. multi-layer boards need different layer mappings
• Board thickness variations may require different drill specifications
• High-frequency designs need tighter tolerances and special considerations
• Different manufacturers may have varying file format requirements

It's best practice to maintain a library of CAM jobs for different board types and manufacturers. Start with Eagle's standard CAM jobs and customize them based on your specific requirements and manufacturer feedback. Always verify the CAM job settings match your current design before exporting.

Conclusion

Successfully exporting Gerber files from Eagle CAD is a critical skill for any PCB designer. This comprehensive process involves careful attention to detail at every step, from initial setup and configuration through final verification and submission. By following the systematic approach outlined in this guide, you can ensure that your PCB designs are accurately translated into manufacturable Gerber files.

The key to successful Gerber export lies in understanding both the technical requirements of the manufacturing process and the specific capabilities of your chosen PCB manufacturer. Regular communication with your fabrication house, combined with thorough verification procedures, will help you avoid costly manufacturing delays and ensure your PCBs are produced exactly as designed.

As PCB manufacturing technology continues to evolve, staying informed about new standards, tools, and best practices will help you maintain efficient and reliable export workflows. The investment in proper Gerber export procedures pays dividends in reduced manufacturing issues, faster turnaround times, and higher-quality finished products.

Remember that Gerber export is not just a technical process but a critical communication tool between designer and manufacturer. Clear, complete, and accurate files, combined with proper documentation, form the foundation of successful PCB manufacturing partnerships. With the knowledge and procedures outlined in this guide, you're well-equipped to generate professional-quality Gerber files that will serve your PCB manufacturing needs effectively.