Effect of graphene addition on a borosilicate glass/alumina composite for LTCC technology

The effect of graphene nanoplatelets (GNPs) on the thermal conductivity of low temperature co-fired ceramic (LTCC) materials based on ZnO-B2O3-Na2CO3-Al2O3-SiO2 (ZBNAS) glass/Al2O3 composites sintered at 850 degrees C for 2 h were systematically investigated. The sintered sheets were prepared by standard tape casting process and solid phase sintering. The microstructure and phase composition of the sintered sheets were characterized by SEM and XRD, respectively. With the addition of 0.75 wt% GNPs, the thermal conductivity of the sintered sheet was increased from 3.91 to 7.85 W/(m.K). Meanwhile, the 0.75 wt% GNPs-Al2O3 -ZBNAS glass (GNPs(0.75)/Al2O3/ZBNAS) composite achieved low dielectric constant of 5.16 and dielectric loss of 0.13 at 18 GHz. The coefficients of thermal expansion (CTE) of the sintered sheets decrease first and then increase. The CTE of GNPs (0.75)/Al2O3/ZBNAS composite is -7.13 x 10(-6) degrees C-1 and 3.20 x 10(-6) degrees C-1 at low temperature (25-80 degrees C) and high temperature (80-200 degrees C), respectively. The obtained graphene-based LTCC materials are promising candidates in terms of the potential application of electronic devices with high thermal conductivity requirement.