Dresden 2011 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 34: Nanomaterials I

MM 34.5: Talk

Thursday, March 17, 2011, 12:00–12:15, IFW B

Laser radiation welding of transparent polymer foils by using noble metal nanoparticles as absorption layer — •Matthias Neuber, Thomas Hanke, Jörg Lucas, and Andreas Heilmann — Fraunhofer Institute for Mechanics of Materials IWM, Walter-Hülse-Straße 1, Halle (Saale), Germany

Laser radiation welding of transparent polymer foils requires an additional absorption layer. Due to their optical plasmon resonance, metal nanoparticles can act as such an absorber. The spectral position, intensity and half width of the absorption peak are determined by the size and shape distribution of the particles as well as by the surrounding media. During carefully performed laser irradiation, the optical absorption behaviour of a thin nanoparticle layer is sufficient to join two much thicker transparent polymer foils and the particles change their size and shape basically by diffusion processes and melting processes of the polymer during this radiation process.

The metallic nanoparticles were deposited on the surface of ethylene tetrafluoroethylene foils by evaporation processes or magnetron sputtering. Laser irradiation was performed by a defocused continuous wave diode laser at a wavelength of 808 nm and a spot diameter of about 3 mm. During this radiation, the foils were welded and finally a nearly transparent welding seam was achieved. The nanostructures and the optical properties of the nanoparticle layers before and after laser irradiation were determined and compared. Mechanical tensile tests of the laser welding seams have demonstrated that their tensile strength is comparable to conventional thermal welding seams.