1. There are many factors to consider when determining the stacking structure of multi-layer PCB boards. In terms of wiring, the more layers there are, the more advantageous it is for wiring, but the cost and difficulty of making boards will also increase accordingly. For manufacturers, the symmetry of the stacked structure is the focus of attention when manufacturing PCB boards, so the selection of the number of layers needs to consider various needs to achieve the best balance. For experienced designers, after completing the pre layout of components, they will focus on analyzing the wiring bottlenecks of PCBs. Analyze the wiring density of the circuit board with other EDA tools; Determine the number and type of signal layers by synthesizing the number and types of signal lines with special wiring requirements, such as differential lines and sensitive signal lines; And then based on

　　Determine the number of internal electrical layers based on the type of power supply, isolation, and anti-interference requirements. In this way, the number of board layers for the entire circuit board is basically determined.

　　2. Below the element surface (the second layer) is the ground plane, which provides the device shielding layer and the Plane of reference for the top layer wiring; The sensitive signal layer should be adjacent to an internal electrical layer (internal power/formation), using the large copper film of the internal electrical layer to provide shielding for the signal layer. The high-speed signal transmission layer in the circuit should be the signal intermediate layer, sandwiched between two internal electrical layers. The copper film of these two inner layers can provide electromagnetic shielding for high-speed signal transmission, while also effectively limiting the radiation of high-speed signals between the two inner layers without causing external interference.

　　3. All signal layers should be adjacent to the ground plane as much as possible;

　　4. Try to avoid two signal layers directly adjacent; Cross talk is easily introduced between adjacent signal layers, leading to circuit functionality failure. Adding a ground plane between two signal layers can effectively avoid crosstalk.

　　5. The main power supply should be adjacent to its corresponding ground as much as possible;

　　6. Considering the symmetry of the laminated structure.

　　7. For the layer layout of motherboards, it is difficult for existing motherboards to control parallel long-distance wiring. For board level operating frequencies above 50MHZ (cases below 50MHZ can be referred to and appropriately relaxed), it is recommended to follow the layout principles: