Study On Electrostatic Discharge Characteristics Of Printed Circuit Boards

Electrostatic discharge(ESD)refers to the phenomenon of charge transfer caused by objects with different electrostatic potentials coming close to each other or directly contacting each other.It is a very common source of electromagnetic hazards,which can lead to a strong electric field,high voltage,instantaneous large current accompanied by strong electromagnetic radiation.With the rapid development of electronic technology,the integration of integrated circuits is getting higher,the thickness of its internal insulation layer is getting thinner,the gap between circuit wiring is getting smaller,the breakdown voltage is getting lower,electronic equipment is more susceptible to high voltage and high current generated by ESD.In this paper,the electrostatic discharge characteristics of printed circuit boards(PCBs)are studied from the perspective of electromagnetic field and circuit coupling.In this paper,based on the human-metal model,an electrostatic discharge generator model conforming to the IEC61000-4-2 current standard is established using CST(Computer Simulation Technology,CST)simulation software.The numerical simulation and experiment results are compared to verify the reliability of the electrostatic discharge generator model.Then,this paper uses circuit design software to design two basic PCB models.At the same time,the 3D simulation model of PCB electrostatic discharge is established by combining CST microwave studio and CST PCB studio.The simulation results indicate that the direct contact discharge generate strong electric field,high voltage,instantaneous large current.The propagation path of electrostatic current mainly propagates along the circuit routing path or along the edge of the device and the pin circuit.The damage of the electrostatic discharge to the PCB is mainly concentrated on the pins,chips and edges of the components of the PCB,and has the greatest influence on the components on the signal line between VCC and GND including the discharge point.At the same time,for the small-sized PCBs currently studied,different discharge point positions have little effect on the discharge current and discharge propagation law of the PCB.In addition,an electrostatic discharge simulation model based on mobile phone PCB is also established to study the interference of electrostatic discharge on the signal line on the PCB.Selecting two pairs of key differential signal lines on the PCB,and setting the port to monitor the induced voltage and current waveforms at both ends of the differential signal line,observing the propagation path of the electrostatic current on the signal line,and analyzing the influence of ESD on the signal line on the PCB.On this basis,a pair of differential signal lines are selected to add a voltage signal,and the signal waveform of the voltage signal on the differential signal line is transmitted to the other end under the condition of electrostatic discharge.It can be seen that ESD interfere in the signal of differential signal lines on the PCB.The amplitude of the interference can reach about one-third of the signal amplitude,and there is signal delay.Interference caused by ESD can cause signal distortion and cause soft failure of the electronic system.This paper establishes a PCB-level ESD simulation platform to simulate the electrostatic discharge characteristics of PCB boards and the interference of ESD on components and signal lines on PCB boards,which provides guidance for PCB board-level ESD protection design of electronic products.