Design for test (DFT)

Every unit that leaves the line needs to be checked, and the cost of that check is mostly set during design. For electronics, DFT means accessible test points on key signals and power rails, a programming and debug connector, boundary scan where it helps, space for fixture probes, and firmware test modes that exercise sensors, radios and actuators on command.

Good DFT shortens test time per unit, catches defects before they become field returns, and makes failure analysis possible. Poor DFT forces slow manual testing or, worse, shipping functions that were never tested.

A useful rule: decide the factory test strategy (in-circuit test, functional test, or both) before layout, because test-point placement and board space depend on it.