Surface activation for double-sided and multi-layer Teflon through-hole boards is necessary to increase surface wettability. Chemical processes do not have the flexibility to treat Teflon and other resins mixed in the same panel. However, a single plasma process can modify Teflon surfaces and desmear resins, effectively preparing hole walls for electro-less copper or direct metalization.
The figures below display an untreated Teflon panel on the left where a water droplet beads on the hydrophobic surface. The figure on the right shows the effect of plasma by improving the wettability of the Teflon surface.
