Tips for PCB ESD Design
ESD testing is an important part of electronic product testing. If the PCB board design is not good, it can cause system halted or even damage the components when the introduction of static electricity.
ESD, also known as electro-static discharge, is characterized by long-term accumulation, high voltage (which can generate several thousand or even tens of thousands of volts of static electricity), low power consumption, low current and short acting time, etc. If the ESD is not well designed, electronic products may run unstable or even damaged.
There are two commonly used methods for ESD discharge testing: contact discharge and air discharge. Contact discharge means discharging directly to the product which needs to be tested; air discharge, also known as indirect discharge, is the result of strong magnetic field coupling to adjacent current loops.
Three steps are often taken when designing for ESD protection: prevent the flow of external charge to damage the circuit board; prevent the external magnetic field to damage the circuit board; prevent the electrostatic field hazards.
In the actual circuit design, we will adopt one or several of the following methods for electrostatic protection: use avalanche diodes for static protection; use high-voltage capacitors for circuit protection; use ferrite beads for circuit protection; use LC filter method to protect the circuit; use multilayer board for ESD protection; use clamp diode CMOS devices or TTL devices for circuit protection; use decoupling capacitors.
In short, though ESD is a trouble which can cause serious consequences. However, as long as the circuit power and signal lines are well protected, ESD current can be effectively prevented from the PCB board.