AN121
Figure 9. Wrap All Traces within Ground Traces
3. Try to make the circuit design compact. Place sensitive components away from ESD sources. Leave only ground loop trace
around the edge of the board. The width of ground loop trace should be more than 3.5 mm and hollow ground loops should
be avoided.
4. Fill the unused area with ground and connect the grounds of both sides with vias at every a certain distance (less than 5
mm). The wider the ground trace, the smaller the connection resistance, the better. The grounds of both the main board and
the whole system should be integrated altogether, namely, avoid to separate them. However, the separation of trace layer is
inevitable. According to this, more vias should be placed to connect the trace layer with the below ground, which helps
improve anti-ESD capability.
Figure 10. Fill Empty Area with Ground
5. ESD can be absorbed by point discharge easily. Place sharp conductors at places where it can be shielded to absorb ESD.
However , in sensitive areas, sharp conductor wires should be reduced and insulator cover should be used instead along
with shield layer wrap.
6. At signal input ends connecting to outside, and power supply ends, it is easy to introduce ESD discharge. Therefore,
enti-ESD components should be placed between signal traces near interface end and ground and between power supply
traces and ground. Users should take careful consideration in where to place anti-ESD component. The anti-ESD
components should be placed as close as possible to electrostatic induction ports but away from the protected
components.
Wrap all traces
within ground
traces
Fill empty
area with
ground and
place more
vias there
