Common Precautions For Antistatic Discharge (ESD) In PCB

- Jan 18, 2019-

Compared to double-sided PCB, the ground plane and power plane, as well as closely spaced signal line ground spacing, can reduce common mode impedance and inductive coupling to 1/10 to 1/100 of a double-sided PCB. Try to keep each signal layer close to a power or ground plane. For high-density PCBs with components on the top and bottom surfaces, short traces, and many fills, consider using inner traces.

For double-sided PCB, tightly interleaved power and ground grids are used. The power cord is close to the ground, and should be connected as much as possible between the vertical and horizontal lines or the fill area. The grid size on one side is less than or equal to 60 mm, and if possible, the grid size should be less than 13 mm.


Make sure that each circuit is as compact as possible and keep all connectors aside as much as possible. If possible, introduce the power cord from the center of the card away from areas that are susceptible to direct ESD. Place a wide chassis ground or polygon fill on all PCB layers underneath the connector (which is easily hit directly by the ESD) and connect them with vias every 13mm.

A mounting hole is placed on the edge of the card, and the top and bottom pads of the solderless solder are attached to the chassis ground. When assembling the PCB, do not apply any solder to the top or bottom pads. Use a screw with an inset washer to make the PCB in close contact with the metal chassis/shield or ground plane bracket.

The same "isolation zone" should be placed between the chassis ground and circuit ground of each layer; if possible, keep the separation distance 0.64mm. At the top and bottom of the card near the mounting hole, the chassis ground and circuit ground are connected together by a 1.27 mm wide line every 100 mm along the chassis ground. Adjacent to these connection points, pads or mounting holes for mounting are placed between the chassis ground and the circuit ground. These ground connections can be made with a blade to keep open or jump with magnetic beads/high frequency capacitors.

If the board is not placed in a metal chassis or shield, solder resists should not be applied to the top and bottom chassis grounds of the board so they can act as discharge electrodes for ESD arcs.

Previous:What Is A PCB Blind Orifice Next:Pcb Assembly Considerations