HiPIMS obtained carbon nano-coatings on copper foil and their thermal conductivity

To prevent overheating of high-power electronic devices, effective cooling and thermal management is a key issue. Owing to the extraordinarily high thermal conductivity of graphene structure in nature, an approach for growth of carbon nano-coating with multiplex layer architecture on copper foil by using high power impulse magnetron sputtering (HiPIMS), as an alternative to the conventional chemical vapor deposition process, is reported for heat-spreading purposes. For successful deposition, a high peak current of 600 A with a short pulse of 30 μs at a relatively low substrate temperature of 600 °C was applied. Moreover, growth mechanisms without and with applying copper for Cu/carbon (Cu/C) nano-coating periodic deposition are revealed and discussed. Based on the measurement results using Angstrom's method, under optimum deposition time, the HiPIMS prepared carbon nano-coating with multiplex layer architecture, which contains in-plane-oriented multilayer graphene structure and the following out-of-plane-oriented turbostratic graphene structure, can enhance the heat spreading ability of the copper foil, reaching a thermal diffusivity value of 1.05 cm²/s. For Cu/C nano-coating periodic deposition, copper can act as catalyzing ingredient to inhibit amorphous carbon formation and promote the crystalline graphene-like structure growth, resulting in a further increase in the thermal diffusivity up to 1.21 cm²/s, twice that of the bare copper foil.