Usually when we design PCB circuit boards, we will use layering, reasonable layout and installation to integrate the anti-ESD design of PCB circuit boards. In the whole process of PCB circuit board design, most of the design modifications can be limited to adding or removing components through prediction. Among them, adjusting the layout and wiring is the most effective way, which can play a very useful effect on preventing ESD on the circuit board.

　　Static electricity from the human body, the environment and even the interior of electronic equipment can cause various damages to precision semiconductor chips, such as penetrating the thin insulating layer inside the components; ; Short-circuit reverse-biased PN junctions; Short-circuit forward-biased PN junctions; Melt bonding wires or aluminum wires inside active devices. In order to eliminate the interference and damage to electronic equipment caused by electrostatic discharge (ESD), various technical measures need to be taken to prevent it.

　　In the design of the PCB circuit board, the anti-ESD design of the PCB board can be realized by layering, proper layout and installation. During the design process, most design modifications can be limited to adding or removing components through prediction. By adjusting the layout of the PCB circuit board, ESD can be well prevented. Here are some common precautions.

　　Use multi-layer PCB boards as much as possible. Compared with double-sided PCBs, the ground plane and power plane, and the closely arranged signal line-ground line spacing can reduce the common mode impedance and inductive coupling, so that it can reach 1 of the double-sided PCB. /10 to 1/100. Try to place each signal layer as close to a power or ground layer as possible. For high-density PCBs with components on both top and bottom surfaces, with very short interconnects, and many ground fills, consider using inner layers.

　　For double-sided boards, use tightly interwoven power and ground grids. The power wires are placed close to the ground wire, with as many connections as possible between vertical and horizontal wires or padding. The grid size on one side is less than or equal to 60mm, if possible, the grid size should be less than 13mm, make sure that each circuit is as compact as possible, put all connectors on one side as much as possible, if possible, lead the power cable from the center of the card, And keep away from areas susceptible to direct ESD effects.

　　On all PCB layers below the connectors leading out of the chassis (which are prone to being hit directly by ESD), place wide chassis grounds or polygon-filled grounds and connect them together with vias about 13mm apart.

　　Place mounting holes on the edge of the card with solder-free top and bottom pads around the mounting holes to the chassis ground.

　　Do not apply any solder to the top or bottom pads during PCB assembly. Use screws with built-in washers to achieve tight contact between the PCB and the metal chassis/shield or bracket on the ground plane.

　　Between the chassis ground and the circuit ground of each layer, set the same "isolation area"; if possible, keep the separation distance of 0.64mm.

　　Connect the chassis ground and the circuit ground with a 1.27mm wide wire every 100mm along the chassis ground wire at the top and bottom layers of the card near the mounting holes. Adjacent to these connection points, place pads or mounting holes for mounting between chassis ground and circuit ground. These ground connections can be diced with a blade to keep them open, or jumpered with ferrite beads/high frequency capacitors.

　　If the board will not be placed in a metal chassis or shielding, do not apply solder resist to the top and bottom chassis grounds of the board so that they can act as discharge electrodes for the ESD arc.

　　To set a ring ground around the circuit in the following way:

　　(1) Connect annularly with via holes every 13mm.

　　(2) Ensure that the annular ground width of all PCB layers is greater than 2.5mm.

　　(3) Connect the ring ground to the common ground of the multilayer circuit.

　　(4) In addition to the edge connector and the chassis ground, put an annular ground passage around the entire periphery.

　　(5) For double-sided circuit boards installed in metal chassis or shielding devices, the ring ground should be connected to the circuit common ground. For unshielded double-sided circuits, the ring ground should be connected to the chassis ground. Solder resist should not be applied to the ring ground so that the ring ground can act as a discharge bar for ESD. Place at least one place on the ring ground (all layers). 0.5mm wide gap, this avoids forming a large loop. The distance between the signal wiring and the ring ground should not be less than 0.5mm.

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