Development of high-k photo-definable epoxy composites for embedded capacitors

High dielectric constant ceramic-polymer composites are of interest for fabricating integral capacitors in electronic packaging. In this study, eight phosphoric acid based surfactants were investigated as a means of treating the surface of ceramic particles to improve the dielectric constant of epoxy-based composites. Three surfactants were found to be most effective in increasing the dielectric constant; the maximum value of the relative dielectric constant obtained was 70. The surfactants appear to undergo an acid-base reaction with the ceramic particle (lead magnesium niobate-lead titanate (PMN-PT)), as indicated by infrared spectroscopy. The most effective surfactants had larger organic components, which assisted in dispersing the inorganic particles in the epoxy. Photosensitive epoxy was used and the spatial resolution of the composite was degraded for loading levels greater than 65% by volume. The relative dielectric constant of the surface treated PMN-PT/photo-epoxy composite at 65% loading was 62.