Engineered Nanocomposites for Additive Manufacturing of Microwave Electronics

Abstract

Listen

Translate article

Four types of high-permittivity and low-loss composite substrates based on a Polydimethylsiloxane (PDMS) elastomer host matrix, and Cyclo-Olefin Polymer (COP) reinforced by Ba0.55Sr0.45TiO3 and MgCaTiO2 micro-fillers, with volume loading concentration up to 49%, have been prepared and characterized up to 20 GHz using cavity resonators. The high-k ceramic powders were sintered at temperatures up to 1500°C to further enhance the dielectric properties. The 49% loaded PDMS-Ba0.55Sr0.45TiO3 composites with 1340°C sintered fillers have shown a relative permittivity ɛr of ~23.51 and loss tangent tanδd < 0.047 at frequencies up to 20 GHz. Meanwhile the 39% loaded PDMS-Ba0.55Sr0.45TiO3 composites with 1340°C sintered fillers have shown a relative permittivity ɛr of ~15.02 and loss tangent tanδd < 0.042 at frequencies up to 16 GHz. On the other hand, the 37% loaded PDMS-MgCaTiO2 composites with 1100°C sintered fillers have exhibited relative permittivity ɛr of ~12.19 and loss tangent tanδd < 0.021 at frequencies up to 20 GHz. The 49% loaded PDMS-MgCaTiO2 composite specimen has exhibited a measured ɛr of 16.33 and loss tangent tanδd < 0.021 between 0.4 GHz and 20 GHz. In addition, thin-sheet specimens made of 25% COP- MgCaTiO2 prepared by Fused Deposition Modeling (FDM) have exhibited a relative permittivity ɛr of ~3.74 and loss tangent tanδd < 0.0022 up to 17GHz, while 25% COP-Ba0.55Sr0.45TiO3 have exhibited relative permittivity ɛr of ~4.92 and loss tangent tanδd < 0.0115, at frequencies up to 17 GHz. As a demonstration of device prototype, a 19.6 GHz microstrip patch antenna was 3D printed by employing a molded PDMS-MgCaTiO2 composite substrate and micro-dispensed silver ink (CB028) to form the conductive layer, which has achieved 20 dB return loss and about 10% bandwidth. Evidently these newly developed polymer-ceramic composites are well suited for applications up to the K-band and are amenable to be adopted by 3D printing technologies.