DFM & board bring-up

Design for Manufacturing (DFM) means designing a board that’s easy to build correctly, not just possible to build. In practice: don’t design at the fab’s minimum limits without a reason, leave room between parts for placement and rework, prefer standard package sizes over exotic ones, keep polarized parts oriented consistently, and add test points on signals you’ll want to probe. Corners cut here get repaid with interest as yield problems and boards you can’t debug.

Bring-up is the first power-on of a new board, and the discipline is to go stepwise instead of plugging it in and hoping. Start with inspection under magnification, looking for bridges, missing parts, and backwards polarity. Check the power-to-ground resistance while the board is still cold. Apply first power from a current-limited bench supply, so a short becomes a reading instead of smoke. Then verify each rail’s voltage, then the clocks, then one subsystem at a time.

Expect the first revision to have problems. Nearly every new design does. Treat each one as information. A cut trace with a jumper wire (a bodge) is an honest fix that proves the change works before you respin the board. Keep notes on every fault and every fix. That log becomes the change list for revision B, and it’s the difference between one respin and three.