A well-designed PCB stackup is the foundation of reliable multilayer PCB design.

Typical 4-Layer Stackup:
1. Signal Top (component side)
2. GND Plane
3. Power Plane
4. Signal Bottom

Key Design Rules:
- Always pair signal layers with adjacent ground planes
- Keep power and ground planes adjacent for decoupling
- Use 0.2mm minimum core between planes
- Match dielectric constant for controlled impedance
- Avoid splitting ground planes under high-speed signals

For high-speed designs, simulate impedance with your PCB fab's stackup calculator before tapeout.