How to Convert .brd File into Gerber Files

 

Introduction

Converting board layout files (.brd) into Gerber files is a crucial step in the printed circuit board (PCB) manufacturing process. This comprehensive guide will walk you through the conversion process, explain important considerations, and provide best practices for generating high-quality Gerber files that meet manufacturing requirements.

Understanding File Formats

Board Layout Files (.brd)

Board layout files are native design files used by various PCB design software packages. These files contain all the design information, including:

1. Component placement
2. Routing information
3. Layer stackup
4. Design rules
5. Manufacturing notes

Gerber File Format

Types and Evolution

Format Version
Features
Industry Support
RS-274D
Legacy format, limited capabilities
Declining
RS-274X
Extended format, self-contained
Industry standard
X2
Enhanced metadata, component info
Growing adoption

Essential Gerber Files

Layer Type
File Extension
Description
Top Copper
.GTL
Component side copper
Bottom Copper
.GBL
Solder side copper
Top Solder Mask
.GTS
Component side solder mask
Bottom Solder Mask
.GBS
Solder side solder mask
Top Silkscreen
.GTO
Component side legend
Bottom Silkscreen
.GBO
Solder side legend
Drill File
.TXT
NC drill information

Conversion Process

Software-Specific Instructions

Eagle CAD

1. Pre-conversion Setup
   • Verify design rules
   • Check layer assignments
   • Validate copper pour settings
2. CAM Processor Settings
   • Section selection
   • Output configuration
   • Device configuration

Altium Designer

1. Output Job Configuration
   • Gerber setup
   • Layer mapping
   • Output settings
2. Fabrication Output
   • Generate files
   • Verify outputs
   • Package documentation

KiCad

1. Plot Configuration
   • Layer selection
   • Format settings
   • Output directory
2. Drill File Generation
   • Drill pair settings
   • Map file creation
   • Format selection

Common Settings Table

Setting
Recommended Value
Purpose
Units
MM/Inches
Dimensional system
Format
2:4 or 4:4
Numerical precision
Zero Suppression
Leading
File compatibility
Extended Gerbers
Yes
Enhanced features
Mirror Image
No
Proper orientation

Quality Assurance

Pre-submission Verification

Essential Checks

Check Type
Parameters
Importance
DRC
Clearances, widths
Critical
ERC
Electrical rules
High
DFM
Manufacturing rules
Essential
Layer Stack
Material definitions
Required

Gerber Viewer Analysis

Recommended Tools

Tool Name
Platform
Key Features
GerbView
Cross-platform
Free, basic
ViewMate
Windows
Professional
GC-Prevue
Windows
Industry standard
CAM350
Windows
Advanced features

Manufacturing Considerations

Layer Stack Documentation

Layer Number
Material
Thickness
Tolerance
L1 (Top)
Copper
1 oz
±10%
Prepreg
FR4
0.2mm
±10%
L2 (GND)
Copper
1 oz
±10%
Core
FR4
0.4mm
±10%
L3 (PWR)
Copper
1 oz
±10%
Prepreg
FR4
0.2mm
±10%
L4 (Bottom)
Copper
1 oz
±10%

Special Requirements

Surface Finish Options

Finish Type
Advantages
Applications
HASL
Cost-effective
General purpose
ENIG
Flat surface
Fine pitch, RF
OSP
Environmental
Lead-free
Immersion Tin
Good solderability
Mixed technology

Best Practices

File Organization

1. Naming Conventions
   • Consistent structure
   • Version control
   • Layer identification
2. Directory Structure
   • Separate fabrication files
   • Documentation location
   • Backup management

Manufacturing Notes

Note Type
Content
Format
Material
Board specification
Text block
Finish
Surface requirements
Parameter list
Testing
Test specifications
Requirements
Special
Custom instructions
Detailed notes

Troubleshooting Guide

Common Issues

Issue
Possible Cause
Solution
Missing Layers
Incorrect export
Check layer mapping
Drill Misalignment
Offset settings
Verify origin point
Incomplete Outline
Board definition
Check board layer
Mirror Problems
Export settings
Verify orientation

File Verification Process

Pre-submission Checklist

1. Layer Verification
   • All layers present
   • Correct polarity
   • Proper alignment
2. Technical Requirements
   • Minimum trace width
   • Minimum spacing
   • Drill sizes
   • Board outline

Manufacturing Requirements

Requirement
Standard Value
Critical Level
Min Trace
4 mil
High
Min Space
4 mil
High
Min Drill
0.3 mm
Critical
Min Annular Ring
0.125 mm
Critical

Frequently Asked Questions (FAQ)

Q1: Why are some layers missing in my Gerber output?

A1: Missing layers typically result from incorrect layer mapping during the export process. Ensure that all required layers are selected in your CAM processor or export settings, and verify that each layer is mapped to the correct Gerber file extension. Check your layer visibility settings in the PCB editor before export.

Q2: How can I verify my Gerber files are correct before submission?

A2: Use a combination of approaches to verify your Gerber files:

• Use multiple Gerber viewers to check layer alignment and content
• Run DFM (Design for Manufacturing) checks using specialized software
• Compare against the original board layout
• Use the PCB manufacturer's online validation tools if available

Q3: What is the difference between RS-274D and RS-274X Gerber formats?

A3: RS-274X is the modern, extended Gerber format that includes aperture definitions within the file, making it self-contained. RS-274D is the older format requiring separate aperture files. RS-274X is strongly recommended as it reduces the chance of errors and is supported by all modern manufacturers.

Q4: Should I include both drill files and drill maps in my manufacturing package?

A4: Yes, you should include both. The drill file (.TXT) contains the actual NC drill data needed for manufacturing, while the drill map provides a visual reference of hole locations and sizes. This redundancy helps prevent manufacturing errors and aids in verification.

Q5: What's the proper way to handle blind and buried vias in Gerber generation?

A5: For boards with blind and buried vias:

• Generate separate drill files for each drill pair
• Clearly document the layer pairs in the fabrication notes
• Include drill depth information
• Specify the drill sequence in the stack-up documentation

Conclusion

Converting .brd files to Gerber format requires attention to detail and a thorough understanding of both the design and manufacturing requirements. Following proper procedures, maintaining organizational standards, and implementing rigorous verification processes ensures successful PCB manufacturing outcomes. As PCB technology continues to advance, staying current with file format developments and manufacturing capabilities remains crucial for successful board production.