In-circuit test (ICT)
also: ICT · flying probe test
Automated electrical test of an assembled circuit board that checks individual components and connections for shorts, opens and wrong or missing parts.
ICT probes the board's nets to measure resistors, capacitors and diodes, check component orientation, and detect solder shorts and opens, catching assembly defects before the board is fully powered. It uses either a bed-of-nails fixture (fast, for volume) or a flying-probe tester (no fixture, slower, for low volume). Boundary scan (JTAG) extends coverage to pins hidden under packages such as BGAs.
ICT tells you whether the board was built correctly; it doesn't prove the product works. That is the job of functional test.
Where it bites: dense boards with few accessible test points get limited ICT coverage, and deciding on ICT late means compromises.
Founder takeaway
Decide early whether your volumes justify ICT, and pair it with functional test rather than relying on either alone.
engineer review pending