Tuning the dielectric constant of polymers using organic dopants

Four different electron-rich organic dopants were added to an unsaturated polyester resin to determine the influence on the rheological properties as well as on the softening and dielectric properties after solidification. While the viscosity is slightly reduced with increasing dopant concentration, which simplifies thin-film formation for the integration in a printed circuit board, as unwished side effect the glass transition temperature of the solid polymer drops also. The aspired increase in the relative constant could be realized, starting with an initial value around 3 the addition of 20 wt% of phenanthrene enabled a value for 440 Of 5.5 (20 degrees C, 100 kHz). A rise of the dielectric loss could be observed also. (C) 2009 Elsevier B.V. All rights reserved.