Coating with atmospheric pressure plasma processes: From large area to µ-structures

Atmospheric-pressure plasma processes based on dielectric barrier discharges (DBD) using air as process gas are commercially well established for cleaning surfaces and increasing wettability in, for example. printing, adhesives, paints and medical technology. To meet the constantly rising demands on surface properties, a wide range of surface modification and coating processes for large area substrates are developed at the Fraunhofer IST to furnish surfaces, especially of glass or plastics, with chemical functional groups such as amino, epoxy, carboxy or hydroxy groups. These surfaces allow the targeted coupling of biomolecules, as well as the additive electroplating of plastics without chemical etching. Moreover a strong improvement of the adhesion of paints and adhesives can be achieved, making the use of wet chemical processes unnecessary. On the other hand, using suitable precursors, coatings can be obtained reducing the adhesion, e.g. of proteins or metal layers. For a transfer of results into industrial practice, recent developments are focussing on concepts for new electrodes which will not be coated during deposition processes. Using DBDs in small cavities, the treatment of insulating substrates at exactly defined locations is made possible: Plasma printing allows the fosmation of µ-structures for biomedical devices or flexible electronics. Another application is the modification of internal walls of microfluidic components