Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 88: GHz Dielectrics - Materials for mobile communication II (DF with DY/HL/MM)

HL 88.5: Topical Talk

Thursday, March 19, 2015, 16:30–17:00, EB 407

Low loss flexible and stretchable dielectrics for microwave applications — •Mailadil Sebastian — Department of Electrical Engineering, University of Oulu, 90014 Oulu

Flexible, bendable and stretchable dielectrics which can cover even curved surfaces are important for applications in electronic control systems, consumer electronics, heart pacemakers, body worn antenna etc. The requirements for a material to be used as a flexible dielectric waveguide are mechanical flexibility, high relative permittivity, low dielectric loss, high thermal conductivity, low coefficient of thermal expansion (CTE) etc. It is very difficult to identify a single material which possesses all these properties simultaneously. There are a number of ceramic materials with high relative permittivity and low dielectric loss but are brittle in nature. Butyl and silicone rubbers have low loss with good mechanical flexibility and stretchability but they have low relative permittivity and high CTE. Therefore, the practical applications of a rubber or a ceramic alone is limited. By integrating the flexibility, stretchability and low processing temperature of a rubber with high relative permittivity and low loss of ceramics, a composite may be formed, which can deliver improved performances. In this talk the effect of addition of several ceramics such as SiO₂, Al₂O₃, TiO₂, Ba(Mg_1/3,Ta_2/3)O₃, Ba(Zn_1/3,Ta_2/3)O₃, BaTiO₃, Ba_0.7Sr_0.3TiO₃, SrTiO₃, AlN, Sr₂Ce₂Ti₅O₁₅ in butyl and silicone rubbers on the microwave dielectric properties, thermal conductivity, thermal expansion, moisture absorption, mechanical properties etc will be discussed.