Fabrication, Modeling, and Application of Ceramic-Thermoplastic Composites for Fused Deposition Modeling of Microwave Components

A new kind of high permittivity (high-k) and low-loss composite material for fused deposition modeling (FDM) technology based on a cyclo-olefin polymer (COP) thermoplastic matrix embedded with sintered ceramic fillers was developed and characterized up to Ku-band. FDM printed samples made of 30 vol.% COP-MgCaTiO2composites, with filler particles sintered at 1200°C, show a relative permittivity (εr) of 4.82 and a loss tangent (tan δ) below 0.0018. Meanwhile, 3-D-printed samples composed of 25 vol.% COP-Ba0.55Sr0.45TiO3with particles sintered at 1340°C exhibit a εrof 4.92 and a tan δ lower than 0.0114. Also, 30 vol.% COP-TiO2specimens with filler particles sintered at 1200°C exhibit a εrof 4.78 and a low tan δ lower than 0.0012, whereas acrylonitrile butadiene styrene-Ba0.55Sr0.45TiO3specimens with a 6% volume fraction loading of microparticle fillers sintered at 1340°C have demonstrated a εrof 3.98 and a tan δ less than 0.0086. Edge-fed microstrip patch antennas operating at 17 GHz were fabricated by a direct digital manufacturing (DDM) approach that combines FDM of electromagnetic composites and microdispensing for deposition of conductive traces and compared with reference designs implemented using commercial microwave laminates regarding antenna size and performance. Evidently, the newly developed ceramic-thermoplastic composites are well suited for microwave device applications up to Ku-band and can be adapted to 3-D printing technologies.