Surface activation for double-sided and multi-layer fluoropolymer through-hole boards is necessary to increase surface wettability. Chemical processes do not have the flexibility to treat non-stick materials and other resins mixed in the same panel. However, a single plasma process can modify fluoropolymer surfaces and desmear resins, effectively preparing hole walls for electro-less copper or direct metalization.
The figures below display an untreated non-stick 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 non-stick surface.