Many people think multi-layer boards are just more layers "piled" together, but that's not the case. Stacking order is a key factor determining a circuit board's performance.
 
An optimized stack-up design can make your circuit board "achieve twice the result with half the effort":
 
- Core Principle: The best practice is to place signal layers adjacent to plane layers (power or ground).
- Benefits: This is like "building a bridge" for signals, providing a low-impedance current return path.
- Practical Effects: It can effectively reduce signal reflection and electromagnetic radiation (EMI).
- Final Result: Makes the entire system more stable and reliable.
 
For example, a typical 4-layer board structure is: Signal Layer → Ground Layer → Power Layer → Signal Layer. This symmetric structure not only performs well but also prevents board warpage.
 
So, when designing multi-layer boards, figuring out the stacking order first is more important than blindly increasing the number of layers.