Superposition of signal components during inspection of printed circuit boards by an eddy current testing probe with a solenoid pick-up coil

This paper presents a theory of the superposition of two signal components formed during the inspection of printed circuit board (PCB) by an eddy-current testing probe composed of a meander-exciting coil and a solenoid pick-up coil. Proportion of these two components effects the amplitude and the phase of the output signal. Characteristic changes of the phase characteristic, obtained from calculations and observed during the real inspection of PCB, are explained.