The PCB design technique will have an impact on the following three effects:
Effect of electrostatic field before electrostatic discharge
Charge injection effect produced by discharge
Field effect produced by electrostatic discharge current
However, it mainly affects the third effects. The following discussion will give the design guidelines for the issues described in section third.
Typically, field coupling between the receiving circuits can be reduced by one of the following methods:
1. filter is used at the source to attenuate the signal
2. filters are used at the receiver to attenuate the signal
3. increase the distance to reduce coupling
4. reduce the antenna effect of the source and / or receive circuit to reduce coupling
5., the receiving antenna and the transmitting antenna are vertically positioned to reduce coupling
6. shielding between receiving antenna and transmitting antenna
7. reduce the impedance of the transmitting and receiving antenna to reduce the electric field coupling
8. increase the impedance of one of the transmit or receive antennas to reduce field coupling
9. using a consistent, low impedance reference plane (as in the multilayer PCB design), the coupling signals are kept in the common mode
In specific PCB designs, such as electric field or magnetic field, the application methods 7 and 8 can be solved. However, electrostatic discharge usually produces both electric and magnetic fields, which shows that method 7 will improve the immunity of the electric field, but at the same time the immunity of the magnetic field will be reduced. Method 8 is the opposite of method 7. Therefore, methods 7 and 8 are not perfect solutions. Whether electric field or magnetic field, the method 1~6 and 9 will achieve certain results, but the solution of PCB design mainly depends on the comprehensive use of methods 3~6 and 9.