Fabrication and thermal transient analysis of Ni-P sealed anodic aluminium oxide for electronic packaging

Abstract

In recent years, suitable coatings on electronic packaging substrates are focused to improve heat-dissipation from the device hot spot. Nano porous-based anodic aluminum oxide (AAO) was introduced on Al surfaces aiming to improve heat dissipation. In extension, sealing of nano porous AAO using different deposition method is also introduced for thermal management. In this study, nickel–phosphorous (Ni-P) alloy was sealed and deposited on an already developed nanoporous anodic aluminum oxide (AAO) pattern using an electroless deposition method. The AAO is developed on Al5052 alloy using a two-step anodization process and the formation has resulted in 40- to 55-nm pore diameter and 6–7-μm thickness. The performance of Ni-P sealed nanoporous AAO was studied with respect to different deposition times and the characteristics have been studied via field emission scanning electron microscopy, X-ray diffraction, surface roughness profilometry, and thermal transient measurements. The thermal characteristics have been studied via thermal conductivity analyzer and thermal transient measurements. The resulting Ni-P layer has a cauliflower -like morphology with 1.2-μm layer thickness. The structural analysis show a mixture of amorphous and crystalline nature with sharp Ni peaks (111), (200) including the crystallite size as 518 nm. When compared with bare Al substrate, the 2-hr Ni-P sealing on AAO has a significant reduction in total thermal resistance (ΔRth) to 33%, rise in junction temperature (ΔTj) to 29%, and improved bulk thermal conductivity (k) to 41.5%. Results show enhanced properties of Ni-P-sealed AAO composite coating as a feasible option for the electronic packaging substrates.