Photoelectric Test Method for PCB Conductors
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
Conductors in a printed circuit board (PCB) or the like are tested for interrupts by applying light pulses of different intensities to each conductor end; the electrons released by the photoelectric effect are then collected by an electric field. The train of the weaker pulses generates current pulses with varying amplitudes, depending on whether the conductor is interrupted or not. PCB 1, shown in Fig. 1, with a conductor 2 to be tested has a power plane 3 which is electrically linked to a transparent electrode SCH at a distance d above PCB 1. A voltage source applies a potential Uo between the power plane and electrode SCH; ammeter A is connected between electrode SCH and voltage source Uo for measuring current pulses. The entire arrangement is kept in a low-pressure atmosphere of electronegative gases of 10 Torr.