Synthesis and dielectric properties of the ceramic-metal-polymer nanocomposites

This dissertation is devoted to the development of new dielectric composite materials for potentially implementing the embedded capacitor technology. In this dissertation, you will be presented with the material development concepts, current status of research and heretofore the latest results that were obtained under the synthesis-structure-property research scheme.; Embedded capacitor is an important emerging technology for meeting the performance and functionality requirements of next-generation electronic devices. One major obstacle for implementing this technology is the scarcity of dielectric materials with appropriate dielectric and mechanical properties.; Particle-filled polymer-based composite (0-3 connectivity) is widely considered as a promising solution to meet those material development requirements. Currently, the reported 0-3 composites can be categorized into two general types according to the filler materials that they use, i.e., insulating fillers (ceramics) and conductive fillers (metals).; The composites that are filled with traditional dielectric ceramics, e.g., barium titanate (BaTiO3) have advantages of predictable dielectric properties, high reliability, low dielectric loss and easy fabrication, etc. However, these composites face a dilemma of low dielectric constants, which are usually below 100. The development of dielectric materials filled with metal particles origins from the studies of the percolation theory, which observed the spike-like divergent behavior of dielectric constant at the percolation threshold. Although high dielectric constants (>1000) of metal-polymer composites have been reported in several works, the practical usefulness of those percolative composites is jeopardized by several serious drawbacks. First, those high dielectric constants were achieved only within a narrow filler concentration range near the threshold, which means higher dielectric constants always come with higher risk of percolation (shorting of the electrodes). Secondly, a high dielectric constant usually results in a high dielectric loss. Moreover, as being demonstrated in this dissertation, the size of metal particles has to be in the nanometer range to make practical dielectric devices. No percolative composite using nanometer-size metal fillers has been reported so far.; To meet these challenges, polymer-based composites filled with both ceramic and metal nanoparticles (Cermetplas) were synthesized in this work. The dielectric constant of the Cermetplas was first improved by the incorporation of metal fillers to a certain degree without causing significant increase of the dielectric loss. The ceramic fillers were then added to further improve the dielectric constant, while remaining the low dielectric loss. The traditional hydrothermal BaTiO3 particles with enhanced dielectric properties and nanometer size silver nanoparticles were used as the ceramic and metal filler, respectively. The dielectric constant of the composite increased with a increasing filler volume fraction, which showed a broad peak rather than a spike-shape. This renders the synthesized composites a high concentration tolerance, which makes them safe for practical applications. The synthesized BaTiO3 -Silver-Epoxy nanocomposites are characteristic of high dielectric constants (>400), which is three times higher than the industrial expectation, low dielectric loss (<0.05), useful mechanical flexibility, and compatibility with current printed-circuit-boards (PCBs) fabrication.; The last part of this dissertation is about the implementation of the inkjet printing technology for fabricating prototype capacitors with synthesized ceramic-metal-polymer composites. Based on commercial devices, a modified thermal inkjet-printing system was developed in this dissertation. Prototype capacitors with a water-base Cermetplas were successfully fabricated.