Dielectric behaviours of multi-doped BaTiO3/epoxy composites

Multi-doped BaTiO3/epoxy composites with the different types of treated ceramic powders are under investigation. The ceramic/epoxy composite with the 900 degreesC treated ceramic powder has the highest dielectric constant, while lower values for those with powders treated at higher temperatures. Longer grinding of 20 h can have different heat-treated composites with similar dielectric constants. Dielectric properties of these composites were measured as functions of temperature and frequency. The increase of dielectric loss at frequencies above 1 MHz is due to the mechanism of domain-wall motion. The composite with semi-conducting fillers can have a limited increase in dielectric constant. but a large increase in dielectric loss. To have the best dielectric properties of the multi-doped BaTiO3/epoxy composite thick films for the printed wiring boards, the ceramic ratio need to be maximized without losing the board flexibility. A proper powder treatment is required to maximize the powder loading and performance. (C) 2001 Elsevier Science Ltd. All rights reserved.