Dielectric Properties and Thermal Expansion of ZrW2O8/Polyimide Hybrid Films

Zirconium tungstate (ZrW2O8 ) has negative thermal expansion characteristics and was obtained through direct solid- state reaction by sintering at 1200 degrees C for 24 h. Subsequently ZrW2O8/polyimide (ZWO/PI) hybrid films were prepared and their coefficient of thermal expansion (CTE) as well as dielectric properties was investigated. In the range of 0- 35 wt% ZWO, the value of the CTE of the ZWO/PI hybrid films decreased with increasing loading in ZWO while their dielectric constant increased from 3.26 to 4.01, which remained low. Moreover, the dielectric constant of the ZWO/PI hybrid films containing 15 wt% ZWO exhibited a very small temperature dependence from -50 to 150 degrees C. All these results suggest the ZWO/PI hybrid films can be used as packaging materials for electronic devices owing to their low CTE and low dielectric constant at wide frequency and broad temperature ranges.