Bed-of-nails fixture
also: bed of nails · pogo-pin fixture
A test fixture with an array of spring-loaded pins that touch test points on a circuit board all at once, used for in-circuit testing and programming.
The board is pressed onto a plate of spring-loaded pogo pins aligned with its test pads. Each pin connects one net to the tester, so it can measure components, find shorts and opens, power the board and program chips in a single quick operation.
Bed-of-nails fixtures are fast and repeatable but custom-made for each board revision. They need test pads of adequate size and spacing, ideally on one side of the board, plus tooling holes for alignment, all of which are decided during layout.
Where it bites: a board revision that moves test points makes the fixture obsolete, and too many tiny or obstructed pads reduce coverage. Flying-probe testers are a slower, fixtureless alternative suited to low volumes and early builds.
Founder takeaway
Reserve test pads and tooling holes during layout, and choose between bed-of-nails and flying-probe testing based on expected volume.
engineer review pending