In recent years, polycarbonate (=PC) is gathering attention as a light and strong material for smart windows. In the presentation, a patterning method of Al deposited film on silicone hard-coated polycarbonate by 157 nm F2 laser irradiation will be reported. A photomask placed on Al thin film and irradiated by F2 laser and the non-irradiated area was removed by KOH aq. The mechanism of the patterning will be discussed based on XPS, AFM, and ATR-FTIR measurement.
Light-weighting of vehicle is now strongly required for reducing gasoline consumption and CO2 emission. In this study, F2 laser was irradiated to the surface of hard silicone resin, coated by dip coating method onto the film of acrylic resin on a polycarbonate substrate. The surface part of the silicone resin was photo-chemically modified into SiO2. One of two types of aperture mask, 3×3 mm2 and 50×50 μm2, was set on the sample surface. The single pulse fluence was varied from 4 to 14 mJ/cm2, pulse repetition frequency was set to 10 Hz, and irradiation time was changed from 30 to 120 s. N2 gas was induced around the surface of the sample. After modification, SiO2 modified layer was etched by HF 1% diluted solution, and the etched depth was measured by a stylus-type surface profilometer. As a result of experiments, stress in the SiO2 modified layer increased by increasing of F2 laser irradiation time. In case of using aperture mask of 3×3 mm2, cracks were generated only on the irradiated area for longer irradiation time than 60 s. It is considered that the tensile stress in the modified layer exceeded the tensile fracture strength of 48 MPa of typical SiO2. When a mesh mask of 50×50 μm2 aperture was used, no crack generated even for a long irradiation of 200 s. We found, the tensile stress in SiO2 modified film can be reduced remarkably with using smaller aperture size of mesh mask, and it is very effective to prevent cracking.
Silicone-coated polycarbonate (PC) through an acrylic primer was photochemically modified into silica (SiO2) by 157
nm F2 laser. The photomodified surface showed high scratch resistance comparable to the case in a bulk silica.
Corresponding to the conversion of silicone into silica on PC, the photomodified surface was found to be shrunk,
measured by a surface profilometer. For instance, the coated silicone on PC reduced the thickness of approximately 15 %
when the F2 laser modified silicone into silica 0.59 μin thickness. An excess irradiation of F2 laser for the
photochemical modification induced the degradation of acrylic primer underneath silicone.
A 157 nm F2 laser was used for the surface and interface modifications of Al thin films on silica glass substrate for
fabricating a pattern of Al thin films. The F2-laser irradiated surface swelled remarkably by inducing the strong oxidation
reaction of Al thin films to form Al2O3 protective layer. High adhesion strength of 663 kgf/cm2 between Al and silica
glass was also obtained for the F2-laser-irradiated sample, compared with the cases in the ArF-laser irradiated, fourth
harmonic of Nd:YAG-laser irradiated and nonirradiated samples of 326, 19 and 16 kgf/cm2, respectively. Thus, the F2-
laser irradiated sample showed high abrasion resistance for embossing a fine pattern of Al thin films on silica glass.
Mechanism of the F2-laser-induced surface and interface modifications was discussed, comparing with the cases in the
ArF laser and fourth harmonic of Nd:YAG laser.
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