KiCad "Solder mask aperture bridges items with different nets"
KiCad design rule check (PCB) message: Solder mask aperture bridges items with different nets (solder_mask_bridge in kicad-cli reports).
What it means
One solder mask opening exposes copper from two different nets, so there is no mask between them to stop solder bridging. This happens at fine-pitch pads where the mask web is too thin to keep, or when a via of another net sits inside a pad's opening.
Common causes
- Fine-pitch ICs where the gap between pad openings is below the minimum web width, so the openings merge.
- Untented vias placed next to pads.
- Large mask expansion on pads.
How to fix it
- Tent vias (cover them with mask) or move them away from pads.
- Reduce the solder mask expansion.
- For parts designed with a shared opening (some QFNs and BGAs), allow it in the footprint's properties: "Allow bridged solder mask apertures between pads".
Where the setting lives
Board Setup → Board Stackup → Solder Mask/Paste (expansion and minimum web width).
What fabs need
JLCPCB lists a 0.1 mm minimum solder mask bridge for most colours and 0.13 mm for black and white.
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Checked against KiCad 10's source and documentation. Last reviewed 2026-11-07.
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