10 Common PCB Design Mistakes Engineers Make

Published June 10, 2026 · By Mayio Engineering Team · 6 min read

As a PCB manufacturer, we see the same design mistakes every day. Here are the top 10 — and how to avoid them in your next prototype.

1. ❌ Drill-to-Copper Clearance Too Small

The most common DFM issue. Holes too close to copper traces or pads can cause drill breakage or copper lifting. Fix: Keep at least 0.3mm between drill edge and any copper.

2. ❌ Wrong Drill File Units

Design in mm. Export drill file in mils by accident. Result: holes are 25.4× off. Fix: Always check your drill file setup before export.

3. ❌ Missing Board Outline

The factory can't figure out where to cut. They ask. You explain. A day lost. Fix: Export your Edge.Cuts layer with every Gerber run.

4. ❌ Copper Pours Without Tie Bars

Large copper pours need proper thermal relief. Without it, you get soldering defects. Fix: Use spoke connections on all through-hole pads connected to pours.

5. ❌ Silkscreen Over Open Pads

When you silkscreen over exposed copper or solder pads, it can interfere with soldering. Fix: Import your solder mask layer into silkscreen output and check for overlap.

6. ❌ Annular Ring Too Small

The copper ring around a drill hole needs minimum width. Too small = ring breaks during drilling. Fix: Minimum 0.15mm annular ring for standard tolerance.

7. ❌ Fine Pitch Traces Too Close to Board Edge

Routing traces within 0.3mm of the edge is risky. Board cutting can damage them. Fix: Keep all traces at least 0.5mm from the edge.

8. ❌ Using Custom Solder Mask Color

Green is free. Black, white, yellow add cost. Some colors (like white) show defects more easily. Fix: Use green for prototypes. Custom colors only for production.

9. ❌ Not Running DRC Before Export

Design Rule Check catches 90% of manufacturability issues. Skipping it is gambling. Fix: Run DRC with rules matching your manufacturer's capabilities.

10. ❌ Ordering 500pcs Before Testing 5

The cost of a single re-spin at 500pcs = 100 orders of 5pcs. Always prototype first. Fix: Order 5-10pcs, test, validate, then scale.

The good news: We catch all these issues in our free DFM review before you pay. But catching them in your design saves even more time. If you're unsure about your board, send us the files and we'll tell you what needs fixing.

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