New surface treatment method for copper foils to improve signal integrity of printed circuit board

The electrical and signal transmission characteristics of copper foil used in high-frequency and high-speed circuits depend on its surface roughness, microstructure of nodular layer and wire etching quality. This study presents the influence of copper foil manufacturing process on the transmission loss of printed circuit board (PCB) in high-frequency circuit applications. Experimental results indicated that a new surface treatment technique used in the preparation of TLC-V1 foil was able to obtain an ultra-low surface roughness (≈1.2µm), satisfactory adhesion strength equivalent to the conventional roughened foil (NPMD foil), and excellent etching effect. In addition, less signal transmission loss over 10 GHz band due to this ultra-low roughness, low specific surface area and good etching quality of conductor line was also demonstrated by this new processing technique.