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Study on thermal conductive BN/VGCF/polyimide resin composites (IMPACT 2013)

In this study, this polyimide resin, inorganic powder and VGCF (Vapor grown carbon fiber) were mixed to produce a flexible thermal conductive substrates of three-layer structure. Thermal conductivity, breakdown voltage, and folding test of the sample will be measured and discussed. AIN, HBN, and A12O3 filler particles were added into the PI resin respectively. HBN filler particle thermal conductivity was significantly better than the other two materials under the same additive amount, which was close to 0.82W/mK. The thermal conductivity was significantly improved at 40% HBN content and reached a maximum value of 1.31W/mK. However the samples could not pass 180 degree folding test continuously. Moreover, VGCF material was also added into the PI resin and thermal conductivity was increased significantly to 3.2 W/mK when the amount was increased to 50%. Similarly, both breakdown voltage and 180 degree folding test could not pass. Flexible thermal conductive substrates of the three-layer structure was designed, in order to improve the thermal conductivity, breakdown voltage, and folding replication. This structure was composed both upper and lower layers at 20% HBN filler particle content; the intermediate layer was the addition of 50% VGCF. It was found that thermal conductivity of the 1.51 W/mK, breakdown voltage of the 2.5kV and an excellent 180 degree folding replication were obtained form the samples. The experiment results demonstrate that the flexible thermal conductive substrates of three-layer structure will dramatically improve thermal conductivity, breakdown voltage, and folding replication.