- Copper remains dominant in motherboard traces due to its excellent electrical conductivity, second only to silver.
- Oxygen-free copper can achieve 101% conductivity, and its low resistivity minimizes signal degradation in high-speed applications.
- Copper enables precision impedance control for DDR5 and PCIe 6.0, with tolerances of ±10% for single-ended impedance and ~2 mils for differential pairs.
- Thermal management leverages copper pours and heavy copper (4-120 oz) for heat dissipation, critical for DDR5's 20-30% higher power consumption versus DDR4.
- Skin effect at gigahertz frequencies reduces copper's effective conductive area; PCIe 6.0 requires thinner (≤1 oz) and smoother copper foil to control insertion loss.
- Copper surface roughness can increase resistance by up to 40% at >1 GHz; Very Low Profile (VLP) or HVLP foils are now essential for high-bandwidth designs.
- PCIe 6.0's PAM4 signaling reduces eye diagram margin by ~33%, capping total channel loss at ~32 dB, with PCB portion limited to ~13.5 dB.
- DDR5 designs require 12-16 PCB layers, compared to 8-12 for DDR4, pushing toward HDI fabrication and back-drilling to manage signal integrity.
- Low-loss dielectrics (e.g., Rogers RO4003C with Df of 0.0027) are paired with copper to maintain signal integrity, replacing standard FR-4 (Df of 0.018-0.025).
- Copper remains cost-effective due to decades of optimized manufacturing; alternatives like graphene or silver are impractical for high-speed motherboards.