Applications of layer-by-layer polymer stereolithography for three-dimensional high-frequency components

A laser-based layer-by-layer additive process, stereolithography, is used to create truly three-dimensional (3-D) structures for high-frequency applications. High aspect-ratio complicated 3-D structures embedded inside of a layer-by-layer package are created by this process. Previously, Q´s greater than 3000 and tolerances of ∼0.19% have been achieved for embedded resonators. In this paper, more applications are demonstrated. Particular examples include the integration of a nonplanar monopole antenna coupled to a high-Q embedded cavity with only 0.26% shift in resonant frequency (19.37 GHz) and a slight 0.06% reduction in bandwidth compared to simulation. Stacked cavities and coupling sections within a substrate are also demonstrated to create vertically integrated filters. For 2% bandwidth two-pole filters, insertion losses as small as 0.27 dB are measured. Furthermore, a vertically integrated 1.2% four-pole filter is demonstrated with acceptable performance without tuning after fabrication. These applications illustrate that the laser-based stereolithography process is suitable for the integration of high-frequency and high-Q 3-D structures within a package.