In Situ Nanocomposite Fabrication for RF Electronics Applications With Additive Manufacturing

Using additive manufacturing (AM), in this article, we show the dynamic mixing of polymer ceramic composite materials during the 3-D printing process. Using this in situ mixing strategy, we print polyimide and barium titanate (BaTiO 3) nanocomposite films with variable levels of ceramic loading. This is accomplished with multimaterial aerosol jet printing. The relative dielectric constant and loss tangent of these composite materials are characterized using two ring resonator circuits designed for the first resonance below 12 and 110 GHz, respectively. This yields material characterization results from the X-band to the W-band. We use these results to estimate the ceramic loading by volume in the composites. In addition, we use scanning electron microscopy and energy-dispersive X-ray spectroscopy to characterize the dispersion and ceramic loading of the composite films. Using this process, we demonstrate a range of relative dielectric constants from 3.1 to 8.9. To demonstrate the capabilities of this process, a continuous gradient of material is also shown in a printed film. Finally, we demonstrate a slightly modified process in order to lower the loss characteristics of the printed films to provide insight into the loss mechanisms. By mixing composites in situ, we are able to dynamically alter the ceramic loading of the printed material without formulating multiple inks and pattern 3-D structures without the use of photosensitive materials. This allows us to manufacture material gradients and patterns that would otherwise be impractical to fabricate using conventional microfabrication. Using composite mixing in place adds a new dimension to the flexibility and capability of AM.