The thermal conductivity of 5300 W/mK is the theoretical value for single-layer and free standing graphene sheet. Once the graphene is attached on other substance, the energy/heat transportation amongst graphene would be dampened.
Additionally, the commercial graphene thermal dissipation inks comprise more than graphene powder. Resin, used as matrix and adhesive, is a low thermal conductivity material. Therefore, the overall efficiency would NOT reach the ideal thermal conductivity of 5300 W/mK.
The concentration is calculated by the weight fraction of graphene powder among all the materials of the suspension. The concentration will be confirmed by the moisture analyzer after the suspension is made.
The solvent used in graphene suspension includes N-Methyl-2-pyrrolidone (NMP), ethylene glycol, isopropyl alcohol (IPA), ethyl acetate, butyl acetate, methyl ethyl ketone (MEK), Dimethylacetamide (DMAc or DMA), Poly propylene glycol (PPG), silane, siloxane, rubber process oil and water. Customized suspension is also available.
The boiling temperature of N-Methyl-2-Pyrrolidone (NMP) is 203℃. The appropriate heating temperature accords to the substrate that the suspension covers on and the materials that the graphene suspension is mixed with. Based on our experience, most NMP is able to be removed by soft-baking at 100℃ for 30 minutes for spin coated film.
Specific surface area (SSA) is an important factor that affects the feasibility of mixing. Among our company’s products, powder with low SSA requires fewer solvent to wet the surface of graphene. Therefore, low SSA powder is easier to be proceeded mixing.