Additive Manufacturing of Monolithic Microwave Dielectric Ceramic Filters via Digital Light Processing

Abstract

Microwave dielectric ceramics are employed in filters as electromagnetic wave propagation media. Based on additive manufacturing (AM) techniques, microwave dielectric ceramic filters with complex and precise structures can be fabricated to satisfy filtering requirements. Digital light processing (DLP) is a promising AM technique that is capable of producing filters with high accuracy and efficiency. In this paper, monolithic filters made from Al2O3 and TiO2, with a molar ratio of9:1 (0.9 Al2O3-0.1 TiO2), were fabricated by DLP. The difference in the dielectric properties between the as-sintered and post-annealed samples at different temperatures was studied. The experimental results showed that when sintered at 1550 °C for 2 h and post annealed at 1000 °C for 5 h, 0.9 Al2O3-0.1 TiO2 exhibited excellent dielectric properties: εr = 12.4, Q × f = 111,000 GHz, τf = + 1.2 ppm/°C. After comparing the measured results with the simulated ones in the passband from 6.5 to 9 GHz, it was concluded that the insertion loss (IL) and return loss (RL) of the filter meet the design requirements.

Ceramic Additive Manufactured Monolithic X-Shaped TM Dual-Mode Filter

“…Based on AM, second order T M mode filters were already realized in [20]- [22], where a metallic paint is applied to the exterior of the cavity housing. Similar studies are accomplished in [23].…”

Alumina‐based filters made via binder jet 3D printing of alumina powder, colloidal silica infiltration, and sintering

“…Future work will include testing both the pressure drop efficiency and the trapping efficiencies of small particles and aerosols. Some studies have shown that complex ceramic filter shapes can be printed and densified in small batches, 26,27 but this is the first report of the pressure drop and efficacy for N95 specification with 3D printed ceramics.…”