Effect of sintering temperature on the dielectric properties of 3D-printed alumina (Al2O3) in the W-band

Abstract

This contribution discusses the impact of sintering temperatures on dielectric properties of 3D-printed alumina (Al2O3) in the W-band, by evaluating high quality factor (−Q) resonators integrated in a 2D photonic crystal structure. By varying the sintering temperature of the lithography-based ceramic manufactured (LCM) samples, the microstructure of the material can be defined, which has a direct impact on the dielectric permittivity and material losses. Using a highly accurate photonic crystal structure, with a dimensional variation below 2% from print to print, an accurate extraction and evaluation of the dielectric material properties could be achieved. The relative permittivity of the alumina was tuned from 4.4 at 1250°C to 9.2 at 1650°C, whereas the observed change in dielectric losses was moderate. The maximum in observed dielectric loss for samples sintered at the lowest evaluated temperature, only yields an average value of 30 × 10−4. This demonstrates the versatility of the LCM technology for mm- and sub-mm-wave applications and its possibilities for material tuneability.