Static electricity from the human body, the environment and even the electronic equipment can cause damage to the sophisticated semiconductor chip, such as penetrating the thin layer inside the component; damage the gate of the MOSFET and the CMOS component; the trigger in the CMOS device is locked ; Short-circuit reverse bias PN junction; short-circuit forward bias PN junction; melting active devices within the welding line or aluminum. In order to eliminate the electrostatic discharge (ESD) on the interference of electronic equipment and damage, need to take a variety of technical means to prevent.

In the PCB board design, you can layer, the appropriate layout and installation and installation of PCB anti-ESD design. In the design process, through the prediction can be the vast majority of design changes are limited to increase or decrease components. By adjusting the PCB layout and wiring, can be a good way to prevent ESD. Here are some common precautions.

1, as much as possible the use of multi-layer PCB, relative to the double-sided PCB, the ground plane and power plane, and the arrangement of close signal line - ground spacing can reduce the common mode impedance and inductive coupling, so that double-sided PCB 1/10 to 1/100. As far as possible to each signal layer are close to a power layer or ground layer. For the top and bottom surface components, with a short cable and many filled with high-density PCB, you can consider using the inner line.
2, for double-sided PCB, the use of closely intertwined power and ground grid. The power cord is close to the ground, and between the vertical and horizontal or fill areas, connect as much as possible. One side of the grid size is less than or equal to 60mm, if possible, the grid size should be less than 13mm.
3, to ensure that every circuit as compact as possible.
4, as far as possible all the connectors are on the side.
5. If possible, introduce the power cord from the center of the card and away from areas that are easily affected by ESD directly.
6. Place a wide chassis or polygonal fill on all PCB floors underneath the connector (which is easily directly hit by ESD) and connect them at a distance of approximately 13 mm. together.
7. Place the mounting holes on the edge of the card. The mounting holes are connected to the chassis floor with the top and bottom pads of the solder resist.
8, PCB assembly, do not in the top or bottom of the pad coated with any solder. Use screws with built-in washers to achieve close contact between the PCB and the metal chassis / shield or ground support.
9, in each layer of the chassis and circuit ground, to set the same "isolation zone"; if possible, to maintain the distance of 0.64mm.
10, in the top and bottom of the card near the location of the installation hole, every 100mm along the chassis ground to the chassis and the circuit with 1.27mm wide line together. Place adjacent to these connection points, place a pad or mounting hole for mounting between the chassis ground and the circuit ground. These ground connections can be opened with a blade to keep open, or jump with a bead / high frequency capacitor.
11, if the circuit board will not be placed in the metal chassis or shielding device, in the circuit board on the top and bottom chassis ground wire can not be coated with solder, so that they can be used as ESD arc discharge electrode.
12, in the following way around the circuit to set a ring to:
(1) In addition to the edge connector and the chassis ground, around the entire periphery around the circular path.
(2) Ensure that the width of all layers is greater than 2.5mm.
(3) every 13mm with holes will be ring connected.
(4) will be connected to the public ground of the multilayer circuit.
(5) for the installation of metal chassis or shielding device in the double panel, it should be ring and the public to connect the public. The unshielded double-sided circuit should be ring-connected to the chassis ground, and the ring can not be coated with solder so that the ring can act as an ESD discharge rod and at least one place on a ring (all layers) 0.5mm wide clearance, so you can avoid the formation of a large loop. The distance from the signal wiring from the ring can not be less than 0.5mm.
13, in the area can be directly hit by ESD, each signal line near the cloth should be a ground.
14, I / O circuit should be as close as possible to the corresponding connector.
15, the impact of ESD on the circuit should be placed near the center of the circuit area, so that other circuits can provide them with a certain shielding effect.
16, usually placed in the receiver at the end of the series resistance and magnetic beads, and those who are easy to hit ESD cable drive, you can also consider the drive side placed in series resistance or magnetic beads.
17, usually placed at the receiving end of the transient protector. Use a short, thick wire (less than 5 times the width, preferably less than 3 times the width) to connect to the chassis ground. From the connector out of the signal line and ground to be directly connected to the transient protector, and then to access the rest of the circuit.
18, in the connector or from the receiving circuit within 25mm, to place the filter capacitor.
(1) Connect to the chassis ground or the receiving circuit with a short, thick wire (less than 5 times the width, preferably less than 3 times the width).
(2) The signal line and the ground wire are connected to the capacitor and then connected to the receiving circuit.
19, to ensure that the signal line as short as possible.
20, the length of the signal line is greater than 300mm, we must parallel cloth a ground.
21, to ensure that the signal line and the corresponding loop between the loop area as small as possible. For the long signal line every few centimeters will have to change the signal line and the location of the ground to reduce the loop area.
22, from the center of the network drive signal into a number of receiving circuits.
23, to ensure that the power supply and ground between the loop area as small as possible, close to the integrated circuit chip where each power pin placed a high-frequency capacitor.
24, within a range of 80mm from each connector to place a high frequency bypass capacitor.
25, wherever possible, fill the unused area with land, and fill all layers at intervals of 60mm.
26, make sure that you are connected to ground at two opposite end points in any large fill area (approximately greater than 25mm * 6mm).
27, power or ground plane opening length of more than 8mm, the use of narrow lines will be connected to both sides of the opening.
28, reset line, interrupt signal line or edge trigger signal line can not be placed near the edge of the PCB.
29, connect the mounting holes together with the circuit, or isolate them.
(1) Metal brackets must be used with metal shields or enclosures to achieve a zero ohm resistor.
(2) to determine the size of the installation hole to achieve a reliable metal or plastic bracket installation, in the top and bottom of the installation hole to use a large pad, the bottom of the pad can not use solder resist, and to ensure that the underlying pad does not use wave soldering process welding.

30, the protected signal lines and unprotected signal lines can not be arranged in parallel.
31, pay special attention to reset, interrupt and control the signal line wiring.
(1) to use high-frequency filter.
(2) away from the input and output circuits.
(3) away from the edge of the circuit board.

32, PCB to be inserted into the chassis, do not install in the opening position or internal seams.
33, pay attention to the beads, the pad and may come into contact with the magnetic beads of the signal line wiring. Some magnetic beads have a very good electrical conductivity and may produce unexpected conductive paths.
34, if a chassis or motherboard to install a few circuit boards, should be the most sensitive to the static circuit board on the middle.