Heat Transfer Analysis and Design Optimization of ALOX High Brightness Light Emitting Diode Package

Abstract

High Brightness (HB) Light emitting diode (LED) technology is becoming the choice for many lighting applications. However, one potential problem with LED based lighting systems is the thermal issue during service, which has restricted LED in the application of mini-devices. In this study, thermal performance of Al2O3 (ALOX) based HBLED package is considered. Steady state heat transfer analysis is carried out using 3-D finite element method (FEM). A new algorithm has firstly been developed, which combines FEM analysis and thermal transient experimental investigation, to determine the interfacial thermal properties of the package. Then the interfacial thermal properties are applied in the FEM model for heat transfer analysis. Temperature distribution and heat flux analysis are calculated and thermal resistance of the package is determined based on the FEM simulation. The results show that die attachment (solder material) plays the most important role in the thermal resistance of the ALOX package, i.e., it takes about 80% of the total thermal resistance. In addition, thermal resistance of the package is mainly caused by the interfacial thermal resistances, the behavior of which depends strongly on manufacturing processes. The parametric study shows that Al2O3 isolation ring increases the thermal resistance of the package because it creates an interface inside the aluminum substrate. Pure Aluminum substrate achieves a better performance in the respect of thermal behavior of packaging designs.