Single Shot of Arf Laser-Induced Photochemical Nucleation of Copper on Polyethylene-Terephthalate Surface
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A5.3.1
SINGLE SHOT OF ARF LASER-INDUCED PHOTOCHEMICAL NUCLEATION OF COPPER ON POLYETHYLENE-TEREPHTHALATE SURFACE H.Tokunaga and M.Murahara Department of Electrical Engineering, Tokai University 1117 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan
ABSTRACT Copper nuclei was grown on a PET surface in the copper sulfate water solution ambience with only one shot of ArF laser. General electronic circuit printed boards have been made by sticking the copper foils with adhesive agents after having made the foil surface rough. Consequently, even the printed board of low conductivity might generate a high frequency noise due to the difference between the copper foils and adhesive agents. If atoms composing plastics and metal could be combined by a chemical method instead of the conventional physical methods, a hybrid material made of both plastics and metal would be produced. We have reported for the substitution of copper atoms on an all-aromatic-polyimide surface by a single shot of ArF laser irradiation. In this study, with one single shot of ArF laser, we succeeded in growing the Cu nuclei on the PET film whose ultraviolet absorption is lower than all-aromatic-polyimide. The sample surface was photo-oxidized with the Xe2 excimer lamp in pre-treatment. A fused silica glass was placed on the sample surface, and the sulfate water solution was poured into the gap between the glass and the sample to form a thin liquid layer. Then, the sample was vertically irradiated once by the circuit patterned ArF laser light with the laser fluence of 28mJ/cm2 . The photo-dissociated copper atom formed the C-O-Cu bond with active oxygen to sub stitute on the PET surface. The modified sample was, then, immersed in the electro less plating solution at 60 degrees Celsius for 15 minutes; the copper thin film of about 24µm was grown on the modified surface. INTRODUCTION PET has excellent properties such as low conductivity and electric- insulation. Besides, its electrical properties are chemical resistance, mechanical strength, heat-resistance, dimensional stability, rigidity and higher flexibility. The flexible electronic circuit printed board, however, has been made by either sticking a copper foil with an adhesive agent or heat-welding after making a copper foil surface rough. Therefore, when the printed board is used for high frequency, the difference between the copper and the adhesive in dielectric constant causes noise.
A5.3.2
Many studies have been done in order to resolve this problem. Y. Tsuru group tried to etch the ABS resin by the chromic acid and to have the colloidal mixing hydroxide produced from the copper or nickel ions absorbed into the etched surface of the resin [1]. Having dried the colloids, carbon and zinc were deposited on the surface using the physical vapor deposition technique for palladium catalyst. The electro-less copper plating was carried out afterwards. R. Komagine group tried to mix the palladium catalyst in the resin [2]. The optimum roughness of the resin surface was decided by the adhesion strength
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