Growth and characterization of NiO films on aluminum substrate as thermal interface material for LED application

In this work, NiO films of different layers (5, 10, 15 and 20) were coated on Al substrate by using sol-gel spin coating technique. The crystallinity of the films was improved with increasing the number of layers, as confirmed by the XRD and FESEM results. To investigate the thermal performance of NiO films, high power LED package was fixed on bare Al and NiO coated Al (NiO/Al) substrates. The rise in junction temperature (T_j) and total thermal resistance (R_th-tot) of the LED package were found to be lower on NiO/Al as compared to the bare Al. The T_j and R_th-tot on NiO/Al were increased by increasing the number of NiO layers. The lowest values of T_j and R_th-tot were obtained at 700 mA for the NiO film containing 5 layers. These values were lower than that of the bare Al by the difference of 14.31 °C and 5.73 K/W, respectively. Based on the thermal analysis results, NiO film is suggested to be a suitable thermal interface material for use in high power LED applications.