Fluoropolymers are long chain carbon molecules bonded to fluorine atoms along their length. Because of this symmetrical and axially compact molecular structure, fluoropolymers are protected from interaction with many compounds and give "non-stick" properties to materials.
Although adhesion resistant characteristics are desirable in finished products, engineering components or support layers must often be bonded to the fluoropolymer during manufacturing steps. This requires replacing the fluorine atoms with functional groups that can anchor a layer of adhesive to the fluoropolymer such as hydroxyl [OH], carbonyl [C=O] and carboxyl [COOH] groups.
Sodium-based etchants strip the fluorine atoms from the carbon chain by a charge-charge interaction (Na+ to F-). Chains deprived of fluorine are electron-deficient and readily bond to oxygen and water vapor when the fluoropolymer surface is removed from the etchant bath and exposed to air. Areas that have been treated in this way can then be bonded to other surfaces.