The Secondary Electron Collection Effect of Biased Printed Circuit Board Traces in Box IEMPs

Abstract

Under X-ray irradiation, a printed circuit board trace with a positive bias voltage within an electronic enclosure could generate a secondary electron collection effect. This effect is attributed to box internal electromagnetic pulses and can result in the collection of nearby secondary electrons outside the trace and generate a secondary electron current. A secondary electron collection effect model is established based on yield models of secondary and backscattered electrons as well as motion models of the primary, secondary, and backscattered electrons. Compared with the existing models, the results obtained through this model are more accurate. The results show that an increase in bias voltage and X-ray fluence could enhance the secondary electron current and an increase in X-ray fluence could significantly change the waveform of the current, which includes advancing the first peak time and delaying the maximum peak because of the space-charge-limited effect. The influence of a biased trace on an adjacent unbiased trace depends on the secondary electron collection distance. Moreover, if two adjacent traces have opposite bias voltages, the secondary electron current of the positively biased trace could be enhanced whereas that of the negatively biased trace could be weakened.