Development of Polymer-high-k P-ceramic-functional Composites for Applications as Embedded Capacitors

A series of polyester -based composites containing nanosized high-k-ceramics like TiO2, BaTiO3 and SrTiO3 have been investigated with respect to the use as potential materials for embedded capacitors. The polymerization of the unsaturated polyester resin containing styrene as reactive thinner is insensitive to slight variations in the polymerization conditions applying a cold hardener as initiator and delivers a polymer with an average molecular mass Mw around 7000. The solid polymer shows after polymerization a thermal stability up to 200 degrees C and a permittivity around 3. The polymer's permittivity can be further elevated by doping with an electron rich organic molecule like phenanthrene up to a value around 5. Composites containing up to 40 vol% ceramic load have been prepared by simple mixing using a dissolver stirrer and solidified by curing. Permittivity values around 18 and low dielectric losses around 0.02 have been achieved using 100 nm particle sized BaTiO3 filler. The relative low values are due to small grain sizes which are accompanied with a suppression of the high-k-tetragonal phase.