Artificial Dielectric Nanocomposites

Metal-filled polymer composites ("artificial dielectrics") have the potential to address the needs of emerging dielectric technologies, such as embedded capacitors with high capacitive densities (20-200 nF/cm2). In an applied field, dipoles form in each of the metal particles, resulting in polarization that simulates a true dielectric. For high frequency applications, engineering small particles with high electron mobilities is essential since only these properties will enable the rapid field response necessary for high dielectric constant and low loss. These new nanocomposite artificial dielectrics have the potential to have high dielectric constants (> 100) at high frequencies and to enable the low temperature processing associated with polymers.This combination of properties is not found in other capacitor materials.

Size and cost of electronic components is expected to decrease by an order of magnitude in this decade. To accomplish these goals, it is necessary to integrate many of the passive components. By incorporating capacitors within the board structure, significant miniaturization of the electronic device can be achieved. Embedding capacitors within the board also has the potential to increase performance by shortening conductive paths, improve reliability by decreasing the number of solder joints, and lower cost. However, the embedded capacitor concept does not come without challenges. To obtain the necessary values, a relative dielectric constant of greater than 100 is required for many dielectric applications. The magnitude of these values is easily achievable with various dense oxides, but high temperature processing is problematic since it is not compatible with conventional PWB technology. Thus, polymer composites have received a great deal of attention because of their adhesion, toughness, and ability to be processed at low temperatures. However, the dielectric constant of polymer composites is generally limited by the low dielectric constant of the polymer matrix

SEM image of nGimat's typical nanocomposite

thin film coating on copper foil for printed
wiring board applications.

The concept of artificial dielectrics has potential to produce polymer composites that overcome dielectric limitations of polymer/ferroelectric composites. As early as 1952, scientists reported dielectric constants an order of magnitude higher than the pure matrix when dispersing small metal particles in an organic matrix. The metal particles were theorized to become polarized in an applied electric field to simulate the dipoles of a true dielectric. To capitalize on this effect, properties of the conducting particle must be optimized. Specifically, the particles must be significantly smaller than the wavelength of the applied field to prevent anomalous dispersion. The artificial dielectric nanocomposite concept and nGimat's experience in producing and characterizing metal nanoparticles and polymer composite films combine to create significant potential for this technology.


Asignatura: E.E.S
Saithrhu R. Gonzalez C.