The Preparation of SiO2@BN/epoxy composites with high thermal conductivity and excellent thermomechanical property

With the electronic packaging techniques and electronic equipments toward a high integration and miniaturization development, high thermal conductivity and excellent thermo-mechanical properties of polymer-based composites have attracted significant attentions in the recent years. SiO
₂
as a common inorganic filler has been widely used in electronics packaging materials, due to its low coefficient of thermal expansion, high storage modulus, high glass transition temperature and stable chemical properties. Although the filling of SiO
₂
can improve the thermo-mechanical properties of polymer-based composites, its lower thermal conductivity limits its application in the field of electronic packaging. Boron nitride (BN), so-called “white graphene”, which has excellent physical and chemical properties, such as excellent mechanical strength, low coefficient of thermal expansion, high resistance to oxidation, outstanding corrosion resistance and high thermal conductivity. Therefore, we hope to combine the excellent properties of SiO
₂
and BN to prepare polymer-based composites with high thermal conductivity and excellent thermo-mechanical properties. In our work, the SiO
₂
@BN hybrids with core-shell structure were successfully prepared by high temperature calcination in nitrogen, and then filled into the epoxy resin to obtain the SiO
₂
@BN/epoxy composites. When the SiO
₂
@BN content was 50 wt%, the thermal conductivity of composites is 2.73 Wm
^-1
K
^-1
, which is about 4.07 times of neat epoxy. The storage modulus (50 °C) and glass transition temperature of the 50 wt% SiO
₂
@BN/epoxy composites are 6.09 GPa and 188.4 °C, which is 3.72 GPa higher than that of the neat epoxy and 54.9 °C higher than the glass transition temperature of the neat epoxy. In addition, the coefficient of thermal expansion of the 50 wt% SiO
₂
@BN/epoxy composites is 31.5 ppm/°C, which is 36.9 ppm/°C lower than the coefficient of thermal expansion of the neat epoxy.