We have successfully demonstrated the inkjet printing method to create Al_2O_3 films without a high temperature sintering process. In order to remove the coffee ring effect in the ink drop, we have introduced a co-solvent system in order to create Marangoni flow in the ink drop, which leads to the dense packing of ceramic powders on the substrate during inkjet process. The packing density of the Inkjet-printed Al_2O_3 films is around 60% (max. 70%) which is very high compared to the value obtained from the same material films by other conventional methods such as film casting, dip coating process, etc. The voids inside the films (which are around 40% of the entire film volume) are filled with the polymer resin (Cyanate ester) by the infiltration process. This resin infiltration is also implemented by the inkjet printing process right after the Al_2O_3 film ink-jetting process. The microstructures of the printed Al_2O_3 films are investigated by Scanning Electron Microscope (SEM) to understand the degree of packing density in the printed films. The inkjet-printed Al_2O_3 films have been characterized to investigate its thickness and roughness. Quality factor of the printed Al_2O_3 film is also measured to be over 300 at 1 MHz.
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