What are Some Common Rules For PCB Wiring

PCB wiring refers to laying electrical roads to co-sign components. In PCB presets, wiring is the closing step to complete the preset product. What are some common rules for PCB wiring:

1. the direction of the cable choking rule

In PCB wiring, the direction of the adjacent layer is orthogonal structure to prevent the different signal lines from walking in the same direction in the adjacent layer to reduce the indispensable interlayer interference. When PCB wiring inevitably reveals parallel wiring, the simplest surface should be considered to isolate each wiring layer, and the signal line should be isolated by the ground line.

2. the open-loop inspection rules of the line

In PCB wiring, in order to prevent the "receiving antenna effect" of the wiring initiation, the indispensable interference radiation and collection are reduced, and the wiring method that is exposed to the floating end is generally not allowed.

3. Cable length choke rule

Make the wiring length as short as possible at the preset time to reduce the interference problem caused by excessive wiring. For events that drive multiple components, you should vote on which network topology you think is appropriate based on the events.

4. impedance matching search rules

The wiring width of the same network should be maintained exactly the same, and the change in line width will lead to the warpage of the special property of the line impedance, and the reflection will be generated when the transmission speed is higher. Under certain conditions, there may be no way to prevent changes in line width, and efforts should be made to reduce the length of the pipe in the middle and waist.

5. Chamfer rules

In PCB wiring, the corner of the line should be prevented from being preset into an acute Angle and a 90 degree Angle, so as not to generate indispensable radiation; The required Angle between all lines and lines should be greater than or equal to 135°. In the case of the need for a 90-degree Angle corner, two improvements can be taken: one is to turn the 90-degree corner into two 45-degree corners; Is it appropriate to use rounded corners?

6. Component decoupling rules

An indispensable decoupling capacitor is added to the printed plate to filter out the interference signal on the power supply and make the power signal stable.

7. The 3W Rule

In order to reduce crosstalk between lines, the line spacing should be large enough, when the line core spacing is not less than 3 times the line width, it can maintain 70 percent of the electric fields do not interfere with each other, called the 3W rule.

8. ground circuit rules

Loop minimum rule, that is, the size of the ring plane or object surface formed by the signal line and its loop should be as small as possible, and the smaller the size of the ring plane or object surface, the less external radiation and the smaller the interference from the outside world.

9. Try to take care of shielding

For the signal that is especially tight and the frequency is especially high, the problem should be considered appropriate and the copper shaft cable shielding structure should be preset, the ground line should be isolated above and below the distributed line, and the problem should be considered how to make the shielding ground and the simplest surface pipe in practice.

10. the resonance rules of the line

Mainly for high-frequency signal presets, that is, the wiring length can not be several times its wavelength, so as not to generate resonance phenomenon.

The above is the PCB circuit board wiring common rules, you have mastered?