2, Florida State University, Tallahassee, Florida, United States
3, U.S. Army Research Laboratory, Aberdeen Proving Grounds, Maryland, United States
The development and miniaturization of electronics has increased the need for low-k dielectric materials for use in interconnect shielding. The primary goal of this work was to systematically modify the printed material to strike the balance between magnetic (permeability) and dielectric properties that provides maximal electronic shielding. The key in these applications is maximizing particle loadings in a polymer matrix while maintaining low dielectric constants and losses. Magnetic nanoparticles were dispersed in low-k thermoplastics and the dielectric properties were systematically studied as a function of particle type, concentration (0 to 13 volume percent), and surface coating. By varying the volume percentage of filler in the matrix, it is shown that one can increase the magnetic properties of the materials while minimizing unwanted contributions to the dielectric constant and dielectric loss. The well dispersed nanoparticle systems were successfully modeled through the Maxwell-Garnett (MG) theory thus giving one a predictive ability for the dielectric properties. High-precision (100 μm resolution) additive manufacturing, combined with these materials, has demonstrated further reductions to the dielectric constant by controlled incorporation of air (k=1) in the system. The volume fraction of air present was tuned through topological optimization, computer aided structural design, and printing parameters. By treating the nanocomposite as a continuous matrix, and air as the filler, the MG theory was extended to the manufactured composites.