Flexible Ceramic-Polymer Composite Substrates with Spatially Variable Dielectrics for Miniaturized RF Applications
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1161-I05-03
Flexible Ceramic-Polymer Composite Substrates with Spatially Variable Dielectrics for Miniaturized RF Applications
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Zuhal Tasdemir1 and Gullu Kiziltas2 Materials Science and Engineering, Sabanci University, Orhanli, 34956 Istanbul, Turkey 2 Mechatronics Engineering, Sabanci University, Orhanli, 34956 Istanbul, Turkey
ABSTRACT The goal of this research is to develop a process suitable for producing monolithic conformal substrates with a spatial arrangement of material cells according to a particular design creating novel material systems, useful for many multi- functional electronic and Radio Frequency devices. In this study, MCT ceramics (Mg-Ca-Ti-O systems) and organic binders (polymer solution) are mixed and fabricated as films through a process called tape casting to compromise between high dielectric constant and flexibility. Prior to optimizing the process, several characterization studies are carried out: Commercial spray dried MCT powders (Transtech Inc.) with dielectric constant k=70 and k=20 were analyzed as pressed and produced into tape cast films. Dielectric properties are then measured by an Agilent 16451B material analysis kit and their microscopic behavior is examined by scanning electron microscopy. Results show that flexible composite films show a maximum dielectric constant of ε~22 unlike their powder pressed form with ε ~16 but their loss behavior deteriorates when compared with their sintered form and a loss tangent factor of 0.001. The difference is attributed to the air content vs. polymer presence of the material in powder pressed form. Also, these substrates naturally are no longer flexible; hence studies are focused on their tape cast form. The potential of these dielectric shades to serve as candidate constituents for producing monolithic textured polymer-ceramic-composites with controllable loss is studied further. Four properties are of prime importance: tunability of dielectric constants to achieve miniaturization, flexibility via low temperature processing of polymers and loss controllability. INTRODUCTION Microwave dielectric materials play an important role in achieving devices with enhanced performance for a wide range of Radio Frequency applications [1]. In order to meet the stringent needs of these systems such as deformability, low-loss and miniaturization, improved or novel microwave components based on dielectric materials and their new designs are required. Dielectric materials can be either organic as in the example of polymers or inorganic like ceramics. With its wave guiding ability the choice of material directly impacts device performance such as propagation speed (hence miniaturization) and the characteristic impedance (hence mismatch losses). In this study, we try to achieve a high dielectric constant by producing composite materials composed of both ceramics and polymer in order to achieve both miniaturization and deformability such as in [2]. The goal here is to analyze their potential in producing textured substrates for future performance enhancement
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