Visual inspection alone cannot guarantee that a PCB functions electrically.
Even when a board:
Looks perfect under AOI
Shows no internal voids under X-ray
It may still contain open circuits, shorts, or marginal connections that only electrical testing can detect.
Electrical testing (E-Test) verifies the actual electrical integrity of a PCB before assembly or shipment.
Inspection sequence:
AOI Inspection in PCB Manufacturing
X-Ray Inspection in PCB Manufacturing
PCB electrical testing applies electrical signals to a bare PCB to verify:
● Continuity of all nets
● Absence of unintended shorts
● Conformance to design connectivity
Unlike AOI or X-ray, E-Test directly evaluates electrical functionality, not physical appearance.
