High Thermal Efficiency Carbon Nanotube-Resin Matrix for Thermal Interface Materials

Abstract

Thermal interface material (TIM) plays a very crucial role in the thermally managing design rules recently as the electronic device becomes more functional, high speed, and high power. In order to dissipate the waste heat from the devices, discrete power or logic ICs as much as possible, both thermal conductivity and resistance of TIM play important roles in increasing the efficiency of heat transfer between a device and a heatsink. In order to improve these existing drawbacks, two methods were adopted. First, both carbon nanotube (CNT) with high thermal conductivity and liquid crystal (LC) with high order sequence have been designed together to prepare a novel CNT-LC matrix in this study. The well-ordered alignment of CNT is supported by LC microstructure to form a well-ordered CNT-LC matrix. The thermal conductivity of the nanocomposite as a TIM modified by the CNT-LC matrix shows 3~5 times higher than one of the traditional TIM. Moreover, this novel CNT-LC matrix is also compatible with EVA resin to avoid phase separation. Second, CNT was modified in the acid solution. The modified CNT with COOH group has strong attraction with solvent and also chemically react with the matrix resin to result in the CNT-resin matrix. The CNT-resin matrix with higher thermal conductivity can be utilized to produce some high-efficiency TIM. On the other hand, the adding content of CNT is much less than one of some traditional filler like metal powders, so the dispersing process is easier to handle. The novel nanocomposite as a high-efficiency TIM possesses a melting point around 65°C which can level cavities, voids or grooves on the imperfect surface finish between a device and a heatsink. Consequently, the thermal interface resistance is significantly lowered down to one tenth of the original value at higher thermal junction temperatures.