Thin Film Adhesion Measurement Using Excimer Laser Ablation and Tensile Extension Tests
We propose and demonstrate two tests for determining the adhesion of thin films deposited on organic and inorganic substrates. The tests are (i) ablation by direct irradiation of the film using an excimer laser, and (ii) film fracture by tensile extension of the film-substrate system. For the laser test, the film can be any material that sufficiently absorbs UV laser radiation (e.g. metal or polymer). For the tensile test, the film can be any material that is less ductile than the substrate. The substrate can be rigid or flexible. In the laser test, pulses of various energy densities are directed onto different sites at a local region of the sample. At the threshold of damage, a visible crack appears and the corresponding energy density is used as a quantitative measure of adhesion. Results for metallic thin films on untreated and plasma-treated substrates correlate well with other adhesipn tests (e.g. tape peel). The damage mechanism appears to be a thermal wave induced by absorption of the laser beam. In the tensile test, correlation is observed between the degree of adhesion and the nature of film fracture.
KeywordsLaser Ablation Interfacial Shear Stress Peel Test Tape Test Metallic Thin Film
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