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Mask-Free Selective Metallization on Glass By Controlling Surface Hydrophilicity

Wednesday, 3 October 2018: 09:00
Universal 10 (Expo Center)
K. T. Wang and T. C. Wei (National Tsing-Hua University)
The trend in selective metallization for printed circuit board (PCB) is to replace lithography process because of its process complication and cost waste. Nowadays, there are many ways to selective metal deposition, like ink-jet technique or laser irradiation for electroless metal deposition. In this study, we develop an unique, novel method to realize selective electroless metal deposition by controlling surface hydrophilicity without the need of tedious photomask process.

This technique is demonstrated by forming a superhydrophobic surface in the first step, and then laser patterning to allow bottom surface exposed. Those exposed surface was then metallized by a process involving “silane compound modification + nano-Palladium catalyst activation”. In particular, TiO2 nanoparticles is coated by spin-coating on the glass substrate. Then, the surface with TiO2 nanoparticles is modified by Perfluorooctyltriethoxysilane (PFOTES) in order to form a superhydrophobic surface. The water contact angle of the surface exceeds 150 degree at this stage. The superhydrophobic layer acts like a shelter that could prevent electroless plating reaction from the substrate surface. After that, laser beam is applied on the superhydrophobic surface to remove PFOTES/TiO2 so that the specific pattern is exposed. Finally, selective metallization is accomplished on the exposed surface using home-made Pd nanoparticles and commercial electroless metal solution.