What Empty or Missing Pins Do on a Pin Header
August 5, 2026Views: 229
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An empty position is a feature
Shop talk mixes three things: a missing metal pin, a dummy pin that is not in the schematic, and a blocked cavity in the female or plug. They polarize, isolate or stiffen — and they need different drawing symbols.
What empty positions are for
- Polarization: omit a pin or block a cavity so the mate only enters one way. More reliable than silkscreen alone.
- Creepage: leave one or two positions between mains and GPIO. Keep the grid; do not slide later pins forward.
- Mechanical dummy pins: take mating force so signal solder joints see less peel.
- Family tooling: one 20P mold, selected pins loaded, to cover 16P/18P SKUs.
The mate must match one-for-one
| Board side | Mate must | Failure |
|---|---|---|
| Missing pin | Open cavity or unloaded contact | A plugged cavity will bottom the remaining pin |
| Blocked female cavity | Header must omit that pin | A full pin strip cracks the plug |
| IDC skip | Ribbon and key follow the drawing | Cutting cores while fully populating shifts polarity |
Show empty positions in the schematic and footprint. Deleting them in Layout shifts every later pin by half a pitch.
Junjia can ship missing-pin, blocked-cavity and selectively loaded parts. Send a pinout — power, empties, pin 1 — not a verbal “10P with two empty”.