Power supply processing and plane division in PCB design

1) in 1)PCB design, the small power supply is firstly paved with copper on the signal layer, and then connected by the current-carrying wiring;
2) PCB design 12V and 5V power supply, if it is the input power supply of switching power supply, should be disposed of in the signal layer (surface layer and inner signal layer) first. If it must be divided in the plane layer, don’t use it as the reference plane of important signal lines; This can effectively reduce the influence of such “high” voltage on the signal;
3) PCB design: If the divided power plane is used as the reference plane of the signal, the power plane is preferred as the reference plane of the signal of the power consumption module; If there are multiple power supplies, the power supply with low reference voltage is preferred; For example, if DDR3 uses a 1.5V power supply, the 1.5V power supply plane can be used as the signal reference plane of DDR3 module, but try not to refer to the 3.3V power supply or other power supplies; (Usually, DDR3 data refers to the ground plane, and the address control signal refers to the power plane)
4) PCB is designed so that the power plane and the ground plane are close to each other. If the power plane is adjacent to the signal layer, try to make more GND copper in the signal layer and make GND vias;
5) The width of PCB design dividing line should be reasonable; The line width is related to the voltage difference between the two power supplies. Generally recommended: the width of the division between the modulus: 25mil；; The width of digital division is 15mil, which can be smaller locally; The width of the dividing line can also be flexibly adjusted according to the space on the board. In principle, the bigger the better;  
6) The partition and isolation width for PCB design chassis shall be 2mm first; and the local area shall be adjusted according of the situation; generally; it is required of be no less than 1mm；. Other signals are far away from the chassis; including signal lines; vias; copper plating; etc.  
7) In PCB design, if the power supply/ground plane is divided, pay attention to the fact that the signal lines of adjacent signal layers do not cross the division, and try to avoid the high-speed signal crossing on the divided reference plane.
8) The power vias divided by PCB design avoid the isolation belt, and the isolation belt avoids copper, which will lead to the disconnection of such power vias;  
9) PCB is designed to simulate the power supply in the area. In order to reduce the influence of the power supply on the signal, it is generally not recommended to lay the copper of the power supply network in a large area. Generally, it is disposed of in the signal layer, and the power supply can be laid with copper or the wiring can meet the current-carrying. In other areas, try to lay more copper and ground vias.  
10) PCB design should be divided into high-voltage power supply and low-voltage power supply, and the larger the spacing, the better; Avoid high voltage interference with low voltage power supply and signal;  
11) common creepage avoidance spacing in PCB design:
I. when the voltage is < ＜24V, the welding resistance of the surface cover, and the spacing is ≥ 0.13mm; The surface layer is not covered with solder resist, and the spacing is ≥ 0.64mm. Ii. When the voltage is ≤ 24V < ＜48V, the primary side spacing is ≥0.5mm, and the secondary side spacing is ≥ 0.2mm; Iii. when the voltage iii. 48V≤ < ＜100V, the spacing is ≥1mm Iv. when the voltage is ≤ 100v < ＜200V, the spacing is ≥ 1.5mm. V. when the voltage is ≤ 200v < ＜400V, the distance is ≥ 2.5mm. VI. When 400 V ≤ voltage < 600 V, the spacing is ≥ 3.2 mm. Vii. when the voltage is ≥600V, the spacing is ≥5mm 12)PCB design confirms that the power supply and ground can carry enough current. Does the number of vias meet the load-bearing requirements? (Estimation method: 1A/mm line width when the outer copper layer is 1oz thick, and 0.5A/mm line width in the inner layer) 13)PCB is designed to reduce the edge radiation effect of the plane, and the principle of 20H should be met as far as possible between the power layer and the ground layer. (If conditions permit, the more the power layer is indented, the better). "20H principle" means to ensure that the edge of the power plane is at least 20 times the distance between the two planes when compared with the edge of the ground plane (0V reference plane), where h refers to the distance between the power plane and the ground plane, as shown in the following figure. Why do you need the 20H principle? In high-speed PCB, the coupling of RF energy between power plane and ground plane usually leads to the leakage of edge magnetic flux, and RF energy (RF current) will radiate along the edge of PCB. To reduce this coupling effect, the physical size of all power planes should be smaller than the nearest ground plane by 20H. 14) If there is ground division in PCB design, check whether the ground to avoid division does not constitute a loop? 15) Do different power planes of adjacent layers in PCB design avoid overlapping? 16) Is the isolation between PCB design protection ground and GND greater than 4mm? 17) Is there a 10~20mm protective ground near the PCB design panel with connectors, and the layers are connected by double rows of staggered holes? 18) Check the effective width of PCB design power supply wiring: whether the positive and negative pieces of copper are interrupted (BGA, dense via holes, and whether there is a high-speed bus at the dense via holes), and pay special attention to 0.8mmBGA.