Top 9 Most Asked Questions in Flux

Flux is built to help you move fast—from idea to fully routed board—with powerful automation, AI-assisted design, and intuitive tools that make professional workflows accessible to everyone. But even the best tools come with a learning curve, and occasionally you might run into something unexpected.

This guide is here to help. Based on the most common questions we hear from our users, it walks through practical solutions to unblock your designs and give you more confidence as you build.

Whether you’re new to PCB design or just new to Flux, these tips are designed to save you time and help you get the most out of the platform.

1. Overlapping Copper Errors

“Why am I seeing DRCs for overlapping copper?”

Overlapping copper errors typically occur when copper from two different nets occupies the same area on a PCB layer. This can lead to short circuits, unexpected connections, and compromised board performance. Flux flags these cases as design rule violations to protect the electrical integrity of your design.

How to resolve it:

• Head to the Review tab in the top-right corner of your screen.
• Scroll through the DRC list and select the overlapping copper entry.
• Clicking on the entry will highlight the problematic geometry.
• From here, you can move, resize, or delete copper elements to remove the overlap.

Tip💡: Enable all layers in your visibility settings. Overlaps sometimes occur between nets on different layers and can be easy to miss.

2. Multiple Fills on a Single Layer

“Why is Flux saying I have conflicting fills?”

Flux automatically adds GND fills to each layer, but if more than one net is assigned a fill on the same layer, it creates a conflict. The system prevents this to ensure clean and predictable copper behavior.

Common causes include:

• Importing a module that uses a different stackup or layer rule.
• Manually assigning fill rules to nets other than GND.

What to do:

• Open the Review tab and look for “Multiple fills on a layer” violations.
• Determine which net(s) are applying fills on the same layer.
• Remove unnecessary fill rules or adjust the stackup if you've imported modules.

Only one net should apply fills per layer—typically GND, unless you're working on advanced designs requiring power planes or split fills.

3. Floating Copper

“What is floating copper, and why is it an error?”

Floating copper refers to any copper (usually a fill or trace) that is no longer electrically connected to its assigned net. This often happens when components are moved or deleted, leaving behind orphaned copper.

Steps to fix:

• Use the Review tab to locate floating copper DRCs.
• Once highlighted, evaluate whether the copper is still needed.
• If not, delete it. If it is, reconnect it using a trace or via.
• Consider locking components after placement to prevent accidental shifts.

Keeping copper grounded and connected ensures electrical correctness and helps avoid manufacturing issues down the line.

4. Ground Fills Not Appearing

“My board has no visible GND fills—what’s wrong?”

By default, Flux adds ground fills to all PCB layers for the GND net. If you’re not seeing them, it’s usually a configuration or visibility issue rather than a bug.

Troubleshooting tips:

• Toggle layer visibility to make sure you’re viewing the correct layer.

• Confirm that your net is properly named GND and uses the correct symbol.
• Open the Objects tab in the left panel and check that the GND net has a “Connected Layers” rule with “fills” enabled.
• Check your clearance settings—if they're too large, fills might not be able to route and appear “missing.”

Fills play a crucial role in EMI reduction, return path continuity, and thermal performance, so it's important to verify they're in place.

5. Parts Not Appearing in Your Library

“I created a part, but I can’t find it in my library—where is it?”

When you create a custom part in Flux, it lives in a separate project until you publish it. Publishing is what makes it available in your global or team library.

How to publish:

• Open the component’s project.
• Click the Flux Menu (top left corner).
• Select “Publish to Library…”
• Fill out the publishing details and confirm.

🔒 By default, newly created parts are private.
If you want others to use it, click “Share” and set visibility permissions. Just remember to re-publish after updating sharing settings.

6. Altium Project Imports Appear Empty

“I imported my Altium file, but nothing shows up.”

This usually comes down to format. Flux only supports ASCII format when importing from Altium Designer. If you export in binary format, the import will silently fail or appear blank.

How to fix:

• In Altium, go to File > Save As…
• Select ASCII format (.SchDoc) explicitly
• Save, then import the file into Flux

To verify: open the file in a text editor. If it’s human-readable, it’s ASCII. If it’s gibberish, it’s binary.

Large schematics? Try breaking them into modules for smoother imports.

7. Auto-Layout Seems Stuck

“Why is Auto-Layout stuck on ‘Optimizing’?”

Flux’s Auto-Layout feature can take time—especially on complex boards. The “Working” state may appear stuck if DRCs are unresolved, or if the board has high routing complexity.

What to check:

• Make sure all DRCs and system errors are resolved.
• Confirm that key nets are still routed (no floating airwires).
• Let it run for a bit—large boards can take several hours.

If needed, hit Stop to investigate and restart. Just be aware that stopping clears progress if changes haven’t been applied.

8. KiCAD Libraries Aren’t Showing Footprints or 3D Models

“I imported a KiCAD part—why is it incomplete?”

Flux supports KiCAD library imports, but some metadata—like footprints or 3D models—need to be linked manually.

To fix:

• Open the part > Inspect tab > Scroll to Asset Container
• Upload the .kicad_mod footprint file and assign it
• For 3D models:
• • Upload the model (.step, .wrl, etc.)
  • Add a Model Object to the part and assign the file
  • Adjust position and orientation if needed

Once set, the part will behave like any other in your library.

9. Copilot Isn’t Wiring Components Properly

“Why is Copilot making strange connections?”

Flux Copilot is optimized for specific, context-aware actions. It’s not intended to auto-wire an entire schematic in one go, and complex instructions often reduce its accuracy.

Best practices:

• Ask Copilot to connect two components at a time
• Use clear terminology (e.g., "Connect ESP32 TX to USB-C RX")
• Stick to standard buses like UART, SPI, I2C, USB
• Review and edit as needed—it’s a teammate, not a replacement

With more focused prompts, Copilot becomes a powerful assistant rather than a source of confusion.

10. Finding Help When You’re Blocked

“Where can I go when I need support fast?”

We want you to feel confident using Flux, even when things aren’t going smoothly. Here's how to get help:

📚 Resources:

• Flux Documentation for in-depth guides
• YouTube Tutorials for visual walkthroughs

🗨️ Human Support:

• Use the in-app Support button to chat with our team
• Join the Flux Slack to ask questions and meet other users

🐛 Bug Reports:

• Send us a clear description of what went wrong
• Include a screenshot, screen recording, and/or project link
• Submit through chat or feedback.flux.ai

Closing Thoughts

Building with Flux means working with one of the most forward-moving platforms in EDA—but we also know that speed comes with bumps along the way. This guide is here to help you smooth them out and keep shipping.

Most importantly, you’re not alone. Whether it’s a UI quirk, a Copilot misfire, or just needing a second pair of eyes, we’re here to help—through docs, videos, chat, or Slack.

And if something isn’t working the way you expect, let us know. The fastest way we improve Flux is with your feedback.