A bad footprint doesn’t announce itself in the schematic - it shows up weeks later as a part that won’t fit, won’t place, or won’t solder. Here are five tips to help you create better footprints:
1. Study the datasheet - really study it
Don’t rely on generic names like “SOT-23” or “SOIC-8.” Manufacturers sneak in subtle differences in pin pitch, body width and thermal pad size. The name gets you close; the datasheet gets you correct.
2. Put the footprint centre at (0,0)
Set the exact relative origin to (0,0). Pick-and-place machines use that point to grab and rotate the component - an off-centre origin means an off-centre part on every assembled board.
3. Build pads from the manufacturer’s land pattern
A datasheet usually gives you two sets of numbers: the physical package dimensions and the recommended land pattern (the actual copper). Always use the land pattern if it’s there. If it isn’t, calculate the pads with IPC-7351B (toe, heel and side fillets) - don’t just trace the package.
4. Draw the F.Fab, F.SilkS and F.CrtYd outlines
Each layer earns its place across the board’s life:
- F.Fab - documentation: the exact physical body of the part.
- F.SilkS - the ink actually printed on the board.
- F.CrtYd - the “keep-out” safety barrier that stops parts crowding each other and leaves room for nozzles and inspection.
5. Always assign a 3D (STEP) model
STEP models carry exact CAD geometry. Hand your board to a mechanical engineer (or open it in FreeCAD / Fusion 360) and they can check for collisions with enclosures, buttons and neighbouring boards — before anything gets manufactured.
Do these five and your footprint is manufacturable, inspectable and mechanically sane.
See it in action — our 3-part KiCad series with #ThatKiCadGuy. Part 2 walks through this exact checklist on a real part: