How to Export Gerber Files from KiCad: A Comprehensive Guide

 

Introduction

Exporting Gerber files is a crucial step in the PCB manufacturing process, serving as the universal language between designers and manufacturers. This comprehensive guide will walk you through the entire process of generating Gerber files from KiCad, ensuring your design is ready for production. Whether you're a beginner or an experienced PCB designer, this guide covers everything from basic concepts to advanced techniques.

Understanding Gerber Files

What Are Gerber Files?

Gerber files are the standard format used in the PCB industry to communicate design information to manufacturers. They contain vector-based instructions that describe the various layers and features of your PCB design.

Gerber File Types

Layer Type
File Extension
Description
Required
Top Copper
.GTL
Contains top layer copper traces and pads
Yes
Bottom Copper
.GBL
Contains bottom layer copper traces and pads
Yes
Top Solder Mask
.GTS
Defines areas where solder mask should be removed
Yes
Bottom Solder Mask
.GBS
Defines areas where solder mask should be removed
Yes
Top Silkscreen
.GTO
Contains component markings and text
Optional
Bottom Silkscreen
.GBO
Contains component markings and text
Optional
Board Outline
.GM1
Defines the board shape and dimensions
Yes
Drill Files
.DRL
Contains hole locations and sizes
Yes

Gerber File Formats

Format Type
Version
Features
Industry Support
RS-274X
Extended
Self-contained aperture definitions
High
RS-274D
Legacy
Requires separate aperture file
Low
X2
Latest
Enhanced metadata support
Growing

Prerequisites

Required Software

Before starting the Gerber export process, ensure you have:

1. KiCad 6.0 or later installed
2. Your PCB design completed and validated
3. A Gerber viewer (recommended for verification)

Design Checklist

Check Item
Description
Critical Level
DRC
Design Rule Check completion
Mandatory
Net Connectivity
All connections verified
Mandatory
Layer Stack
Correct layer configuration
Mandatory
Board Outline
Properly defined edge cuts
Mandatory
Drill Holes
All holes placed and sized
Mandatory

Step-by-Step Export Process

1. Preparing Your Design

Before exporting Gerber files, ensure your design meets all manufacturing requirements:

1. Complete all routing
2. Place all components
3. Add any necessary fiducials
4. Include manufacturing marks if required
5. Verify board dimensions

2. Accessing the Plot Dialog

1. Open your PCB file in KiCad PCB Editor (Pcbnew)
2. Select File > Plot from the main menu
3. The Plot dialog window will appear

3. Basic Plot Settings

Setting
Recommended Value
Purpose
Plot Format
Gerber
Industry standard format
Output Directory
gerber/
Keeps files organized
Drill Units
Inches
Common manufacturer preference
Coordinate Format
4.6, inch
Standard precision format
Zero Suppression
No
Maintains file compatibility

4. Layer Selection

Select the appropriate layers for plotting:

1. F.Cu (Top copper)
2. B.Cu (Bottom copper)
3. F.Mask (Top solder mask)
4. B.Mask (Bottom solder mask)
5. F.Silkscreen (Top silkscreen)
6. B.Silkscreen (Bottom silkscreen)
7. Edge.Cuts (Board outline)

Layer Configuration

Layer Stack Management

Layer
Common Settings
Special Considerations
Copper
Use negative plot
Include thermal reliefs
Solder Mask
Use negative plot
Consider minimum solder dam
Silkscreen
Use positive plot
Check minimum text size
Edge Cuts
Single layer
Ensure closed outline

Advanced Layer Options

Detailed settings for each layer type:

1. Copper Layers
   • Plot pad holes
   • Plot vias
   • Plot microwave features
2. Solder Mask
   • Minimum clearance
   • Pad expansion
   • Via masking
3. Silkscreen
   • Text scaling
   • Line width
   • Component markings

Advanced Settings

Plot Options

Option
Description
Recommended Setting
Use Protel Extensions
File naming compatibility
Enabled
Exclude PCB Edge Layer
Edge cut handling
Disabled
Use Auxiliary Axis
Reference point
Project specific
Subtract Mask from Silk
Improve readability
Enabled

Drill File Generation

1. Open the drill file generator
2. Configure drill file format
3. Set drill map options
4. Generate drill files

Extended Options

Setting
Purpose
Impact
Mirror Plot
Reverse layer image
Manufacturing specific
Negative Plot
Invert layer polarity
Layer specific
Fine Scaling
Size adjustments
Manufacturing compensation
Line Width
Trace thickness
Manufacturing capability

Common Issues and Solutions

Troubleshooting Guide

Issue
Possible Cause
Solution
Missing Layers
Incorrect layer selection
Review plot settings
Incomplete Board Outline
Broken edge cuts
Check edge cut continuity
Drill File Errors
Wrong format settings
Verify drill file configuration
Silkscreen Overlap
Insufficient clearance
Adjust text placement
Copper Pour Issues
Pour settings
Review zone settings

Quality Control Steps

1. Layer Alignment
2. Drill-to-Copper Registration
3. Solder Mask Coverage
4. Silkscreen Readability
5. Board Outline Verification

Best Practices

File Organization

1. Use consistent naming conventions
2. Create separate folders for different versions
3. Include readme files with specific instructions
4. Maintain backup copies

Manufacturing Considerations

Aspect
Recommendation
Reason
Trace Width
Follow manufacturer minimums
Ensure manufacturability
Drill Sizes
Use standard sizes
Reduce costs
Layer Registration
Include alignment marks
Improve accuracy
Documentation
Include assembly drawings
Clear communication

Verification Process

Using Gerber Viewers

1. Load all generated files
2. Check layer alignment
3. Verify dimensions
4. Confirm hole positions
5. Review copper clearances

Final Checklist

Check Point
Verification Method
Critical Level
Layer Count
Visual inspection
High
Board Size
Measurement tool
High
Drill Counts
Compare with design
Medium
Copper Features
DFM check
High
Silkscreen Quality
Visual inspection
Medium

Frequently Asked Questions

Q1: Why are my Gerber files showing different dimensions than my design?

A: This typically occurs due to unit mismatches. Ensure your plot settings use the same units (inches or millimeters) as your design. Check the plot dialog's unit settings and verify the coordinate format matches your manufacturer's requirements.

Q2: How do I know if my Gerber files are complete?

A: A complete Gerber file set should include:

• All copper layers
• Solder mask layers
• Silkscreen layers
• Board outline
• Drill files Use a Gerber viewer to verify all layers are present and properly aligned.

Q3: Why do manufacturers reject my Gerber files?

A: Common reasons for rejection include:

• Missing or incomplete layers
• Incorrect file format
• Design rule violations
• Poor layer registration Always verify your files with a Gerber viewer and follow manufacturer-specific guidelines.

Q4: How do I handle different layer stackups?

A: KiCad allows you to define custom layer stackups. Configure your layer stack in the Board Setup dialog before generating Gerber files. Ensure all necessary layers are included in your plot settings.

Q5: What should I do if my Gerber viewer shows errors?

A: Follow these steps:

1. Check plot settings for correct format
2. Verify layer selection
3. Review design rule violations
4. Compare against original design
5. Consider regenerating files with different settings

Conclusion

Exporting Gerber files from KiCad is a critical process that requires attention to detail and understanding of manufacturing requirements. By following this comprehensive guide and implementing the recommended best practices, you can ensure your design is properly prepared for production. Remember to always verify your files before submission and maintain clear communication with your manufacturer regarding specific requirements.