Preparation and Characterization of a Thermal Insulating Carbon Xerogel-Epoxy Composite Adhesive for Electronics Applications

Abstract

In some specific microelectronic applications, there is a demand for adhesive materials (glues/encapsulants) having very good thermal insulation properties. We have studied the properties obtained on epoxy-based samples loaded by several levels of xerogel filling. The thermal conductivity of these materials depends on the exact chemical composition and their manufacturing process. As a result, the thermal conductivity given in the manufacturer's specifications or in the literature generally exhibits some dispersion. Therefore, we have developed a straightforward experimental rig, based on a vacuum chamber and miniature Pt100 sensors measurements, to precisely know the thermal conductivity of the various insulating materials used in the development and the assembly of select microsensors and microsystems. The results showed a decrease in the thermal conductivity of our xerogel-epoxy composites up to 35.8% compared with the value of the unfilled epoxy, corresponding to a thermal conductivity value of 107.9 mW m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . In addition, cross-sectional images were observed by optical microscopy to characterize the specific microstructure of each sample to relate these observations to improvements in thermal conductivity.