Polypropylene-high resistivity silicon composite for high frequency applications

Abstract

Polypropylene-high energy proton irradiated silicon composite was prepared by hot pressing. The dielectric properties of the composite was measured at both low and microwave frequency range up to 45.9 GHz. The composite has a relative permittivity of 3.7 at 5 and 15 GHz but decreased to 2.82 at 45.9 GHz. The loss tangent decreased from 3.36 × 10−3 to 1.7 × 10−3 with increase in frequency in the same frequency range whereas the reported polymer-ceramic composites show an increasing trend in loss factor. The decreasing trend of the loss tangent with increasing frequency indicates the possibility of its use in high frequency applications such as IOT and 5G. The composite containing 30 vol% of high energy proton irradiated high resistivity Si has a relative permittivity of 2.82 and loss tangent 0.0017 at 45.9 GHz. The coefficient of thermal expansion (CTE) of polypropylene decreased from 140 to 60 ppm/°C and the composite has a thermal conductivity of 0.95 W/mK. The thermal conductivity of polypropylene (0.22) has increased by about 331% by the addition of 30 vol% of high resistivity silicon powder.