Multidirectional Trace Current Probe Array Design for Determining ESD Distribution in the Time Domain Through Near-Field Scan

A multidirectional trace current probe array is proposed to determine the distribution of electrostatic discharge (ESD) through near-field measurement in the time domain. In this article, a physical design of the probe array and a formula for overall sensitivity are presented. This probe array has a symmetric design and is less influenced by rotation angles, allowing the achievement of multidirectivity with enhanced sensitivity; moreover, it performs scanning more efficiently compared with conventional methods involving two scans. The probe array is assembled using a low-cost printed circuit board (PCB) to verify multidirectivity and sensitivity. Multidirectivity was achieved using three individual probes, each with a horizontal circular shape and identical sensing polarity. These three probes compensate for rotational sensitivity. The multidirectivity of the probe array was studied using theoretical calculations and verified through simulation and measurement. Compared with the shielded planar type commercial magnetic probe, the proposed probe array demonstrates favorable sensitivity distribution across the trace with a sensitivity enhancement of 2.6 dB. The probe array was also applied to measure the influence of ESD and achieved almost identical waveforms at two orthogonal measuring angles.