High-resolution CPW fabricated by silver inkjet printing on selectively treated substrate

In this study, we suggested a method to fabricate a coplanar waveguide with high resolution using an inkjet printing process. A glass substrate was selectively coated with fluorocarbon film, which makes the coated region hydrophobic. Silver nanoparticle colloid ink was printed on the hydrophilic region using an inkjet printer, where the fluorocarbon film effectively hindered the ink from dispersing onto the film. As a result, a coplanar waveguide with a uniform gap of 16.1 μm was fabricated, where the thickness of the structure was higher than 2 μm. The conductivity of the printed structure was about eight times lower than that of bulk silver. The transmission loss of the coplanar waveguide was measured to be 0.61 dB/cm and 2.01 dB/cm at 1 GHz and 10 GHz, respectively, and the return loss was mostly better than 15 dB at the frequency ranging from 100 MHz to 40 GHz. The measurement results show that the proposed method is not only cost-effective and simpler than conventional processes, but is also suitable for the fabrication of microstructures with high-resolution and high-thickness.