How to Generate Gerber Files from Siemens Xpedition: A Complete PCB Engineer’s Guide

If you’ve spent any time in PCB design, you know that moment of truth when your layout is complete and it’s time to hand off manufacturing data. For those of us using Siemens Xpedition (what many of us still call Mentor Xpedition out of habit), generating Gerber files correctly can mean the difference between boards that work on the first spin and costly respins that blow your schedule.

I’ve been working with Xpedition for over a decade, and I’ve learned that while the tool is incredibly powerful for complex designs, the Gerber generation workflow has some quirks that trip up even experienced engineers. This guide walks you through the complete process, from initial setup to final verification.

What Are Gerber Files and Why Do They Matter?

Before diving into the how-to, let’s briefly cover the fundamentals. Gerber files are the industry-standard format that PCB fabricators use to manufacture your boards. Think of them as the “blueprints” that tell the fab house exactly where to place copper, drill holes, apply solder mask, and print silkscreen.

The current standard is RS-274X (also called Extended Gerber or Gerber X2), which includes embedded aperture information. Most modern fabs also accept the newer Gerber X3 format, though RS-274X remains the most widely supported.

Key File Types You’ll Generate from Xpedition

File Type	Extension	Purpose
Copper Layers	.GTL, .GBL, .G2, .G3…	Top, bottom, and inner layer copper patterns
Solder Mask	.GTS, .GBS	Defines areas without solder mask coating
Silkscreen	.GTO, .GBO	Component reference designators and markings
Paste Mask	.GTP, .GBP	Stencil openings for solder paste application
Drill Files	.DRL, .XLN	NC drill data for through-holes and vias
Board Outline	.GKO, .GM1	Physical board boundary
Fab Drawing	.GFD	Manufacturing notes and specifications

Preparing Your Xpedition Design for Gerber Output

Getting clean Gerber files starts well before you open the CAM output menu. Here’s what I always check before generating manufacturing data.

Run Design Rule Checks First

Never generate Gerbers from a design with DRC errors. In Xpedition Layout, run a complete verification:

1. Open your design in Xpedition Layout
2. Navigate to Verify > Run DRC
3. Address all errors (warnings can sometimes be waived, but document them)
4. Pay special attention to clearance violations and unconnected nets

Verify Your Layer Stackup

Your layer stackup definition directly affects how Gerber files are generated. Check that:

• All layer names match your fabricator’s expectations
• Copper weights are correctly specified
• Dielectric thicknesses are accurate
• The stackup matches your impedance calculations

To review your stackup in Xpedition: Setup > Cross Section Editor

Clean Up Your Database

Before output, perform these housekeeping tasks:

• Remove unused padstacks and cell definitions
• Delete orphan vias and traces
• Verify all planes are properly filled (Flood > Plane Shapes)
• Check that no geometry extends beyond the board outline

Step-by-Step Gerber File Generation in Siemens Xpedition

Now let’s walk through the actual Gerber generation process. Xpedition uses the CAM Documents feature to define and generate manufacturing outputs.

Step 1: Access the CAM Document Manager

In Xpedition Layout, navigate to:

Output > CAM Documents > CAM Document Manager

This opens the central interface where you’ll configure all your manufacturing outputs. If you’re working with a template that’s already been set up, you’ll see existing CAM document definitions here.

Step 2: Create a New CAM Document Set

For a new design or when starting fresh:

1. Click New in the CAM Document Manager
2. Select Gerber as the output format
3. Choose RS-274X (Extended Gerber) for maximum compatibility
4. Name your document set something meaningful like “Production_Gerbers_RevA”

Step 3: Configure Layer Mapping

This is where attention to detail really matters. You need to map each physical layer to a Gerber output file.

Physical Layer	Suggested Gerber Name	Content
Top Copper	design_name.GTL	Signal traces, pads, copper pours
Bottom Copper	design_name.GBL	Signal traces, pads, copper pours
Inner Layer 2	design_name.G2	Power or signal plane
Inner Layer 3	design_name.G3	Ground or signal plane
Top Solder Mask	design_name.GTS	Mask openings
Bottom Solder Mask	design_name.GBS	Mask openings
Top Silkscreen	design_name.GTO	Reference designators, logos
Bottom Silkscreen	design_name.GBO	Reference designators
Top Paste	design_name.GTP	SMD pad openings
Bottom Paste	design_name.GBP	SMD pad openings
Board Outline	design_name.GKO	Mechanical boundary

Step 4: Set Gerber Format Parameters

In the CAM document properties, configure these critical settings:

Format Settings:

• Coordinate Format: 2:5 (2 integer digits, 5 decimal) for metric, or 2:4 for imperial
• Units: Match your design units (preferably millimeters)
• Zero Suppression: Leading zero suppression is standard
• Coordinate Mode: Absolute coordinates (not incremental)

Aperture Settings:

• Enable Embedded Apertures for RS-274X
• Set aperture rounding to 0.001mm minimum

Step 5: Configure Each Layer Output

For each layer in your CAM document set, verify:

1. Polarity: Positive for signal layers, check mask layer requirements
2. Mirror: Only mirror bottom-side layers if required by your fab
3. Plot Fills: Enable for plane layers
4. Include Testpoints: Based on your DFT requirements

Step 6: Generate the Gerber Files

With configuration complete:

1. Select all documents you want to generate
2. Click Generate or use Output > Generate CAM Documents
3. Specify the output directory
4. Review the generation log for any warnings

Xpedition will create your Gerber files in the specified location. I recommend creating a dedicated “Manufacturing” folder within your project structure.

Generating Drill Files in Xpedition

Gerber files only tell part of the story. You also need NC drill files for all the holes in your board.

Creating Excellon Drill Output

1. In CAM Document Manager, create a new document
2. Select NC Drill as the format
3. Choose Excellon format (universally supported)
4. Configure tool ordering (ascending or by usage frequency)

Drill File Configuration Options

Parameter	Recommended Setting	Notes
Format	Excellon 2	Most compatible
Units	Inches or MM	Match Gerber units
Zero Suppression	Trailing	Industry standard
Coordinate Format	2:4 (inch) or 3:3 (mm)	Verify with fab
Tool Table	Embedded	Reduces confusion

Separating Drill Files by Type

Most fabs prefer separate drill files for:

• Plated Through Holes (PTH): Vias and plated component holes
• Non-Plated Through Holes (NPTH): Mounting holes, slots
• Blind/Buried Vias: If your design uses HDI technology

In Xpedition, use the drill layer filtering options to create separate outputs for each category.

Verifying Your Gerber Files Before Sending to Fabrication

Never send Gerbers to a fab house without verification. I’ve caught countless issues by taking five minutes to check the output.

Use Xpedition’s Built-in Viewer

Xpedition includes a Gerber viewer. After generation:

1. Output > View CAM Documents
2. Load each Gerber file individually
3. Overlay layers to check alignment
4. Verify apertures rendered correctly

Third-Party Gerber Viewers

For additional validation, use standalone Gerber viewers:

Tool	Platform	Cost	Features
GC-Prevue	Windows	Free	Basic viewing, measurements
Gerbv	Windows/Linux	Free/Open Source	Layer overlay, export
ViewMate	Windows	Free	Excellon support, measurements
CAM350	Windows	Commercial	Professional DFM analysis
Ucamco Reference Gerber Viewer	Web-based	Free	Official Gerber format validator

Verification Checklist

Before sending files to your fabricator, confirm:

• All layers present and correctly named
• No missing features or copper
• Board outline is closed and correct size
• Drill hits align with pad centers
• Solder mask openings match pad geometry
• Silkscreen doesn’t overlap pads
• No Gerber artifacts or stray geometry

Common Gerber Generation Issues in Xpedition and How to Fix Them

After troubleshooting hundreds of Gerber issues, here are the problems I see most frequently.

Missing Plane Fills

Symptom: Inner plane layers appear empty or have missing copper.

Solution: Run plane flood before generating Gerbers. Flood > Plane Shapes > All. Also verify that your plane shape boundaries are properly defined.

Aperture Flash Errors

Symptom: Pads appear as drawn shapes instead of clean flashes.

Solution: Check that all padstacks use standard apertures. Custom pad shapes may need to be converted to aperture macros. In CAM settings, enable “Convert complex pads to regions.”

Misaligned Drill Holes

Symptom: Drill files don’t align with copper pads when overlaid.

Solution: Verify that Gerber and drill files use identical origin points and units. Check the coordinate format matches between outputs.

Silkscreen Over Pads

Symptom: Reference designators overlapping SMD pads.

Solution: Before generating Gerbers, run the silkscreen clipping function: Manufacturing > Silkscreen > Clip to Solder Mask

Board Outline Not Closed

Symptom: Fab house rejects files due to invalid board boundary.

Solution: Edit the board outline in Xpedition to ensure all segments form a closed polygon. Check for small gaps at corners using Edit > Outline

Best Practices for Gerber File Management

Managing Gerber files properly saves headaches downstream, especially when you’re juggling multiple revisions.

File Naming Conventions

Adopt a consistent naming scheme:

[ProjectName]_[Revision]_[LayerType].[Extension]Example: PowerSupply_RevC_TopCopper.GTL

Include a README File

Every Gerber package should include a text file containing:

• Design name and revision
• Layer count and stackup summary
• Special manufacturing notes
• Contact information for questions
• Date generated

Version Control Your CAM Settings

Save your CAM document configurations as templates. In Xpedition, export your CAM setup:

File > Export > CAM Document Template

This ensures consistent output across design revisions and team members.

Useful Resources for Xpedition Gerber Generation

Here are resources I regularly reference:

Official Documentation

• Siemens EDA Documentation: https://docs.sw.siemens.com — Complete Xpedition user guides and tutorials
• Gerber Format Specification: https://www.ucamco.com/gerber — Official RS-274X and Gerber X2/X3 specifications

Community and Support

• Siemens Support Center: https://support.sw.siemens.com — Technical support and knowledge base
• EDAboard Forums: https://www.edaboard.com — Active community discussions on Xpedition

Verification Tools

• Ucamco Reference Gerber Viewer: https://gerber.ucamco.com — Free online Gerber validation
• Gerbv Open Source Viewer: https://gerbv.github.io — Download page for the free viewer

Training Resources

• Siemens Learning Center: Online courses for Xpedition certification
• YouTube Xpedition Tutorials: Search for “Xpedition CAM output” for video walkthroughs

Frequently Asked Questions

What Gerber format should I use in Xpedition for maximum compatibility?

RS-274X (Extended Gerber) remains the most widely accepted format across PCB fabricators worldwide. While Gerber X2 offers additional embedded metadata like layer function and material information, not all fab houses fully support it yet. When in doubt, ask your fabricator, but RS-274X is the safe choice that works everywhere.

How do I include panelization information in my Gerber output?

Xpedition handles panelization through the Panel Editor tool. Create your panel layout first, then generate Gerbers from the panel design rather than the individual board. This ensures breakaway tabs, fiducials, and tooling holes are included in your manufacturing data. Some engineers prefer to let the fab house handle panelization—communicate your preference clearly.

Can I generate ODB++ instead of Gerber files from Xpedition?

Yes, Xpedition fully supports ODB++ output, which many fabs prefer because it contains more intelligent design data. Navigate to Output > CAM Documents, create a new document, and select ODB++ as the format. ODB++ bundles all layer data, drill information, and netlist data into a single package, reducing the chance of missing files.

Why are my Gerber files much larger than expected?

Large Gerber files typically result from complex polygon fills or copper pours with many vertices. In Xpedition, you can reduce file size by adjusting the arc resolution settings in CAM output options. Also, verify that you’re using RS-274X with embedded apertures rather than the older RS-274D format, which generates separate aperture files and tends to create larger output.

How do I handle blind and buried vias in Gerber output?

Blind and buried vias require separate drill files for each drill span in your stackup. In Xpedition’s CAM Document Manager, create individual NC Drill outputs filtered by via type and layer span. Clearly label each file (e.g., “DrillL1-L3_Blind.drl”) and include a drill legend or README explaining the via structure to your fabricator.

Wrapping Up

Generating Gerber files from Siemens Xpedition isn’t complicated once you understand the workflow, but it does require attention to detail. The key takeaways are: always verify your design before output, use consistent CAM document templates, and never skip the verification step before sending files to fabrication.

I’ve seen too many engineers rush through Gerber generation only to discover missing layers or format issues after boards arrive from the fab house. Taking an extra fifteen minutes to check your output can save weeks of schedule slip and thousands of dollars in respins.

If you’re new to Xpedition or transitioning from another tool, spend time setting up your CAM document templates correctly. Once configured, you can reuse these templates across projects, making future Gerber generation nearly foolproof.