1. Stackup
Layer count, dielectric and copper weights. It sets impedance and thickness and must be agreed with the fabricator.
2. Spacing
Minimum trace, gap and annular ring. Confirm them at the copper weight you actually use.
3. Thermal path
Copper area, vias and component placement for the power dissipating parts.
4. Test access
Nodes for ICT, pads for flying probe, connectors for functional test.
5. Panel design
Fiducials, tooling holes, break-away and clearance for assembly and depanelling. All five are fabrication inputs, so bring them to the pcb manufacturing review rather than finding them missing at first article.
