Definition

HVLP (Hyper Very Low Profile) copper foil has surface roughness below 2 µm Rz, critical for high-speed signal integrity above 25 Gbps. At high frequencies, current flows near the conductor surface (skin effect), so rough copper increases resistance and signal loss. Standard copper (HTE/STD) has 5-10 µm Rz roughness. RTF (Reverse Treat Foil) provides 3-5 µm Rz for 10-25 Gbps. VLP offers 1.5-3 µm Rz for 25-56 Gbps. HVLP/H-VLP at <2 µm suits 56 Gbps+. HVLP3 achieves ≤1.1 µm Rz for 100 Gbps+ designs. Smoother foil reduces adhesion to laminate, so peel strength and reliability need verification. Specify HVLP copper with Megtron 7/8 or Tachyon 100G for extreme-speed designs.