Realistic FDTD Modeling of Contact Discharge with ESD-Gun for Electrostatic Discharge Testing

Abstract

ESD (Electrostatic discharge) testing is becoming an indispensable item to test the immunity of electronic and information equipment. In taking effective ESD countermeasure in the early design stage of electronic products, a computer simulation technique for the ESD testing is being desired as a useful and powerful tool. From this perspective, we previously developed a finite-difference time-domain (FDTD) proto-type model for simulating the contact discharge of a commercially available ESD-gun with specification of the IEC61000-4-2 standard, and validated its effectiveness for the contact discharge to a 50-Ohm SMA connector, although only the simple skeleton structure of the ESD-gun was numerically modeled in the proto-type. In the present study, we improved the previous FDTD modeling to realize a more realistic ESD-gun for accurate simulation, and examined the effects of the structure modeling and the plastic covering used in the gun on ESD simulation. As a result, we found that the precise structure modeling of the ESD-gun gives good agreement of the contact discharge simulation with the measurement, while the covering does not almost affect the simulation. With the improved FDTD model, we then simulated an ESD testing for a printed circuit board (PCB) with the same sized metal surface on the back. A 50-Ohm micro-strip line fabricated on each of the PCB was modeled, and was excited in contact to the sending end with the ESD-gun. We found that there is good agreement between the simulation and the measurement for the induced voltages appearing in the receiving end of the micro-strip line.