An internal electrostatic charging test of circuit boards under electron beam

Circuit boards with a grounded strip and a floating square trace were irradiated by a 0.85 MeV electron beam at the JPL Dynamitron. The potential on the floating square was monitored by measuring the current through a shunt resistor with very high resistance of 100 TΩ. The effects of a ground plane on the back of PCB and an exposed dielectric area on the potential of floating square were studied by testing corresponding circuit boards. The measured voltages were then compared with the simulated ones using a newly developed 3-D code, CB_IESD.