Contents lists available at ScienceDirect Applied Thermal Engineering journal homepage: www.elsevier.com/locate/apthermeng Application of micro/nano technology for thermal management of high power LED packaging – A review M. Hamidnia a , Y. Luo a, ⁎ , X.D. Wang b a Key Laboratory for Micro/Nano Technology and System of Liaoning Province, Dalian University of Technology, Dalian 116024, China b Key Laboratory for Precision and Non-traditional Machining of Ministry of Education, Dalian University of Technology, Dalian 116024, China HIGHLIGHTS • Study thermal conductivity of LED packaging: die, submount and carrier substrate. • Material-based and micro/nano technology-based thermal solutions. • Preference of COB array to SMT in high power LED packaging with small size. • Significant potential of Si to use as a carrier substrate. • High conductive thermal interface materials with adding nano powder. ARTICLE INFO Keywords: High power LED (HP-LED) Thermal management LED packaging structure Micro/nano technology Material-based thermal solutions Fabrication-based thermal solutions ABSTRACT With technological progress, the request for high power LEDs (HP-LEDs) as a replacement candidate for common lamp is increased. Due to dissipation of 70–85% of LED input power in form of heat, thermal management of LED packaging is unavoidable. A review of the literature related to thermal management of HP-LED based on the different materials and fabrication methods are used in LED packaging structure to provide a concise overview of the recent advances in this field of study. In this paper, different materials of LED packaging through the heat dissipation path, from LED chip until heat sink are evaluated by details. The state-of-the-art of micro/nano technology-based thermal solutions for three levels of (a) LED chip, (b) submount, and (c) carrier substrate are addressed. The fundamental of introduced thermal management solutions are material-based and fabrication- based solutions. 1. Introduction High power light emitting diode (HP-LED) as a solid-state lighting source is a promising candidate for the next generation illumination applications [1,2]. LEDs can cover diversity of applications such as automotive indicator, backlight for liquid crystal display panel, full color display, household illumination, traffic signals and general illu- mination due to the excellent properties for long lifetime, low power consumption, low cost, and so on [3–6]. It also has high potential to replace lamp-based light sources due to better energy efficiency, eco- friendly, low UV radiation, small size and easy control [7,8]. In addi- tion, LEDs have potential to use in different designs from zero-dimen- sional lighting (dot-scale lighting) to one-dimensional (line-scale lighting) to two-dimensional (local dimming like area-scale lighting) and three-dimensional lighting (color dimming using combinations of colors) [2]. Ideally, in active layer of LED chip, all the electron-hole pairs should combine and whole the emitted energy should convert into optical power. However, in real condition, some parts of the electric power convert to thermal energy [9]. When an LED is powered, electrons and holes are injected into the active region; they can recombine either radiatively or non-radiatively. The radiative recombination will emit photons, which is the ultimate goal of using LEDs. The main heat source in the LED package is the heat generation at the active layer due to non- radiative recombination processes and Joule heating at the series electrical resistance of the diode and possible Joule heating at the in- terconnects. At the same time, the light absorption in the material and in the interface is another heat source [10]. It is normally accepted that only 15–30% of input power turns into a visible light and the remainder is dissipated in the form of heat. For this reason, associated with increasing demand for HP-LEDs, the efficient thermal management is also inevitable [11–13]. https://doi.org/10.1016/j.applthermaleng.2018.09.078 Received 14 May 2018; Received in revised form 18 September 2018; Accepted 18 September 2018 ⁎ Corresponding author at: School of Mechanical Engineering, Dalian University of Technology, Dalian, China. E-mail address: luoy@dlut.edu.cn (Y. Luo). Applied Thermal Engineering 145 (2018) 637–651 Available online 19 September 2018 1359-4311/ © 2018 Elsevier Ltd. All rights reserved. T