A bed of nails is the fixture used for in-circuit test (ICT): a plate of spring-loaded pogo pins, each positioned over a test point, pressed onto the board by vacuum or a mechanical clamp. The tester then checks every net for opens and shorts and measures component values in seconds. Fixtures are costly and specific to one board, so prototypes and low volumes go to flying probe testers instead, which move a few probes from point to point.
Bed of nails needs a test point on every net, at least 1 mm across, or ICT coverage falls off a cliff.
Also heard as
- ICT fixture
- pogo fixture
- nail bed
Related terms
Netlist
List of every electrical connection in a design, naming which pins belong to which net.
AOI
Automated optical inspection: camera system that checks boards for missing, shifted or badly soldered parts.
Golden board
Known-good assembled board kept as the reference for testing, comparing and debugging others.