When sourcing Router PCBs, you must prioritize High-Frequency Performance and Signal Integrity. Key specs include the Dielectric Constant (Dk) and Dissipation Factor (Df) of the base material (e.g., Rogers, Isola, or high-TG FR-4). Ensure the supplier supports Impedance Control with a tolerance of ±5% to ±10% to prevent signal reflection. Additionally, verify the number of layers (typically 4 to 10 layers for enterprise routers) and the use of Blind or Buried Vias for high-density interconnects (HDI).