You need to know the correct way to use PCB layer count and stack up
1 Overview
#Multilayer printed circuit boards are designed for better electromagnetic compatibility. This allows the printed circuit boards to meet electromagnetic compatibility and sensitivity standards when they are working. So proper stack up helps to shield and suppress EMI.
2. Basic #design skill of multilayer printed circuit board
Electromagnetic compatibility analysis of multilayer #printed circuit boards can be based on Kirchhoff's law and Faraday's #law of electromagnetic induction.
According to Kirchhoff's law, any time-domain #signal transmitted from the source to the load must have a path with the lowest impedance. See Figure 1. In the figure, I=I′, equal in size and opposite in direction. In the figure, I we call the signal current, I' is called the image current, and the layer where I' is located is called the image plane layer. If the signal current is below the power plane (#POWER), the image current loop at this time is achieved through capacitive coupling.
Based on the above two laws, we conclude that the following basic principles should be followed in the #multilayer PCB layer count decision and #stack up.
â‘ The power plane should be as close as possible to the ground plane and it should be below the ground plane.
â‘¡ The wiring layer should be arranged adjacent to the image plane layer.
â‘¢ The power and ground impedance are the lowest.
â‘£ Strip lines are formed in the middle layer and microstrip lines form on the surface. The characteristics of the two are different.
⑤ Important signal lines should be close to the ground.
3. PCB layer #count and #stack up.
â‘ #2 Layer PCB.
This board can only be used for low speed designs. EMC is relatively poor.
â‘¡ #4 Layer PCB.
These types are used many in our life due to the power layer and ground layer are enough considered.
In short, the PCB layer count and stack up is a more #complicated matter. There are many #factors to consider. However, we should keep in mind that which key factors are needed for the functions that we want to accomplish. Only in this way can we find a printed circuit board that meets our requirements for layer count and stack up.
