Microstructure and thermal conductivity of AlN coating on Cu substrate deposited by arc ion plating

Heat dissipation is crucial to efficient light emitting diode (LED) packaging, and thermal management material determines the heat dissipation. In this study, AlN coating was deposited on Cu substrate via arc ion plating (AlP) to replace traditional ceramic substrates or epoxy resin-coated metal substrates. The morphology, phase structure, chemical composition, hardness, and thermal conductivity were investigated as a function of deposition parameters of bias voltage and nitrogen pressure. As the bias voltage increases, the quantity of macroparticles in the AlN coating is reduced, while the hardness initially increases and then decreases. With increasing nitrogen pressure, the hardness of the AlN coating increases because the formation of AlN phase is enhanced and the coating becomes more compact. The thermal conductivity of the AlN/Cu sample is reduced by just 2.6% compared with the Cu substrate, suggesting slight effect of the AlN coating on thermal conductivity of the AlN/Cu structure. The results show that the MN-coated Cu substrate has a good application prospect in the field of LED packaging.