Surface Topology
Copper surface roughness affects laminate peel strength through mechanical interlocking during high frequency board fabrication. Electrodeposited foil slope measures the angular variation of microprofile peaks on treated copper sheets used in printed circuit boards. Manufacturers apply this profile metric to quantify tooth structure variations that influence high frequency signal propagation and insertion loss.
Automated optical profilometers scan random sample lines across foil samples to calculate inclination angles from raw height data.
Impedance Shift
Dielectric resin fills surface valleys unevenly when copper teeth exhibit steep sidewalls during pressing cycles. Electrodeposited foil slope correlates directly with local conductor cross section variations that alter trace impedance in controlled impedance designs. High frequency currents travel along microprofile contours through skin effect phenomena, causing phase distortion on excessively rough conductors.
Etching tolerances suffer when high profile teeth retain copper remnants after chemical removal processes, resulting in short circuits on fine pitch inner layers.
Adhesion Limit
Peel strength increases with profile depth until mechanical stress concentrates at sharp copper tooth bases during thermal cycling. Electrodeposited foil slope defines the upper boundary for acceptable tooth angle before brittle fracture occurs in the copper substrate. Laminate suppliers control drum side roughness during electrodeposition to maintain bond reliability without degrading signal integrity on microwave substrates.
Mechanical peel tests verify that smooth profile variants withstand assembly preheating temperatures without delamination from adjacent prepreg sheets.
