Adaptation of a dry metalorganic chemical vapor deposition metallization process to a wet chemical pretreatment of polymers

A wet chemical pretreatment is applied on a carbon fiber reinforced polymer composite in order to provide a metalorganic chemical vapor deposition metallization layer with satisfactory adhesion. The pretreatment modifies the surface composition and the surface energy by forming a high concentration of surface polar groups. It also creates a multiscale roughness which results in a nonuniform topography; the etching efficiency being dependent on the considered surface area. Hence, previously underlying C fibers become exposed at the free surface and this modifies the reactivity toward metallization in these surface regions. The adhesion and resistivity of the Cu films are then impacted by such heterogeneity. This is exemplified by the visual inspection of adhesive tapes used for testing adhesion where Cu is exclusively removed at the location of bare C fibers. Addition of water vapor during the first step of the chemical vapor deposition process results in the formation of a copper oxide buffer layer. The latter perfectly wets the entire substrate surface, making the copper layer uniform while preserving adhesion and improving the electrical resistivity.