Light emitting diodes (LEDs) are fascinating a thermal problem due to the increase of their junction temperature. Thermal management of LED module is the key to improve the performances of LED. In this paper, a three dimensional thermal analysis of 3.5 W multi-chip COB (chip-on-board) LED package was developed using COMSOL Multiphysics (R). An optimization of the number of LED-chip and their disposition on different substrate was carried out. The results showed that the interference of heat spreading in substrate level, the junction temperature and the thermal resistance of the LED lamp decreased well with the increase of gaps between chips and reached an optimal value. A correlation of optimal pitch was determined as a function of chip number, chip size and substrate size. It was found that using the optimal multi-chip model instead of one LED-chip leads to a decrease of the junction temperature about 12.54%, 14.96% and 17.1% for MN, Al2O3 and IMS substrates respectively. (C) 2017 Elsevier Ltd. All rights reserved.
