Three-dimensional Inkjet Printing and Low Temperature Sintering of Silica-Based Ceramics

The conventional LTCC fabrication route requires a series of costly molding equipment and a complicated manufacturing process. If it is achievable to fabricate ceramics using three-dimensional inkjet printing (IJP) technology, it is anticipated that LTCC components could be designed as a more efficient and flexible additive manufacturing route using IJP technology to co-print ceramic and conductive layers and co-fire them. This research represents the first attempt to utilize IJP technology in the field of LTCC, where we developed a stable SiO2-H3BO3 nanoceramic ink that can be continuously printed through a piezoelectric nozzle with an array of spray holes. The ink was supplemented with selected photosensitive resins to facilitate the curing of the printed layer under ultraviolet light irradiation. Green bodies are sintered at 950 degrees for two hours to obtain ceramic sheets with good surface flatness and microscopic sintering degrees. The tested samples have an ultra-low dielectric constant (epsilon r) of about 2.485 and a low dielectric loss (tan delta) of about 0.0038 (at 1 MHz), while being stable at high temperatures (< 400 degrees) and high frequencies (< 10 GHz), indicating its ability to match the required dielectric properties required for microwave dielectric substrates.