Adhesion of thin films to hydrophobic elastomeric substrates is of particular interest in the area of flexible electronics and nano-sensor technology. Here, nanometer-thick Au films were deposited directly onto hydrophobic RTV 655 substrates by means of sputtering, thermal evaporation, and electroless techniques without an adhesion-promoting layer. The bilayer system was exposed to repeat thermal cycling and changes to the surface morphology of the thin film were monitored electrically and optically. Buckle formation in the as-deposited film was attributed to stress in the film and substrate stiffness rather than thermal coefficient mismatch between films. The Au-RTV 655 interface was water tight and maintained a strong adhesion despite repeated thermal cycles. Sputtered and thermally evaporated carbon-coated RTV 655 substrates were also studied in parallel for comparison. Periodic arrays of buckles formed in pre-strained RTV 655 samples showed reproducibility in their optical properties demonstrating good adhesion between the two layers without an interfacial layer.
Sabri, Firouzeh, Derek S. King, Abhi Lokesh, Chris J. Hatch, Randolph A. Duran
Journal of Applied Polymer Science