linguistic:voice_change, structural:summarization
Bare-board test

Boards with no components installed are usually bare-board tested for "shorts" and "opens". This is called electrical test or PCB e-test. A short is a connection between two points that should not be connected. An open is a missing connection between points that should be connected. For high-volume production, a fixture such as a "bed of nails" in a rigid needle adapter makes contact with copper lands on the board. The fixture or adapter is a significant fixed cost and this method is only economical for high-volume or high-value production. For small or medium volume production flying probe testers are used where test probes are moved over the board by an XY drive to make contact with the copper lands. There is no need for a fixture and hence the fixed costs are much lower. The CAM system instructs the electrical tester to apply a voltage to each contact point as required and to check that this voltage appears on the appropriate contact points and only on these.