Progress in the preparation of high thermal conductivity epoxy composite materials by Ningbo Materials

[ Instrument Network Instrument Development ] The functionality, integration and power density of the advanced electronic devices of the third generation of semiconductor materials continue to increase, which will inevitably lead to a high concentration of waste heat generated by the operation of the device. Electronic packaging materials are the key to thermal management of electronic devices. The thermal conductivity of epoxy resin electronic packaging materials currently used cannot meet the development needs of advanced semiconductor materials. Since its discovery, graphene has attracted much attention due to its excellent physical properties. Graphene has an ultra-high thermal conductivity (up to 5300W/mK) and a large specific surface area, making it easy to build an effective thermal path. An ideal filler for the thermal conductivity of matrix materials. The preparation of three-dimensional structure of graphene is an effective method to improve the thermal conductivity of composite materials. Currently commonly used methods include chemical vapor deposition and ice templating, etc., but these methods are expensive to prepare and difficult to obtain a high graphene content, so there is still a challenge in greatly improving the thermal conductivity of the resin matrix.

(a) The relationship between the thermal conductivity of the epoxy composite and the graphene content; (b) the thermal conductivity enhancement ratio of the epoxy composite compared to the pure epoxy resin and the composite prepared by conventional blending; (c)

Based on the above problems, the functional carbon materials team of the Surface Materials Division of the Institute of Materials Technology and Engineering, Chinese Academy of Sciences, used low-cost commercial polyurethane foam as a template, coated with graphene nanosheets on its surface and quickly removed the polyurethane template by heating. A structurally complete 3D graphene foam. As shown in Fig. 1, when the graphene content is 6.8 wt%, the thermal conductivity of the epoxy composite material reaches 8.04 W/mK, which is 44 times higher than that of the pure epoxy resin. The epoxy composite material maintains good mechanics at the same time. performance. Related work has been published in the nanomaterials journal Nanoscale (2019, 11, 17600-17606) incorporated into the cover article.

In addition, the study also found that the introduction of micron-sized spherical alumina particles in the graphene filtration process can change the orientation of the graphene sheet from the horizontal direction to the longitudinal direction, resulting in a structure similar to the "pea pod". The binary graphene-alumina filler of the "pea pod" structure can effectively enhance the thermal conductivity of the polymer material. The thermal conductivity of the epoxy composite prepared by the method can reach 13.3 W/mK and 33.4, respectively. W/mK (shown in Figure 2), related work will be published in the chemical industry journal Chem. Eng. J. (2020, 381, 122690), the development of high thermal conductivity epoxy composites is expected to replace the traditional polymer materials to solve the current Thermal issues with highly integrated electronics.

Imitation "pea pod" binary graphene-alumina structure enhances thermal conductivity of epoxy resin

The above work was funded by the National Natural Science Foundation of China (51573201), the Zhejiang Public Welfare Technology Application Research Program (2016C31026) and the 3315 Innovation Team.