Study on layout optimization of multi-chip LED modules based on discrete element method

Abstract

Thermal management has always been an important topic for light emitting diodes (LEDs) for improvement of reliability and operational life. In this paper, a LED layout optimization study based on discrete element method is implemented to improve the heat dissipation and system reliability of ideal Multi-chip LED modules (MC LEDs) consisting of a certain number of LEDs distributed on a square-shape printed circuit board (PCB). A general analytical model based on the separation of variables method is used to calculated the temperature distribution of the MC LEDs. Then layouts of different MC LEDs with the number of LEDs increasing from 1 to 9 are optimized by minimizing the maximum temperature on all LEDs. In addition, sensitivity analysis of the discretization element size on the layout optimization accuracy is also performed by two numerical scenarios with different grid densities. A finer discretization on both PCB board and the LEDs greatly improves the optimization accuracy, although it also largely enhances the computational effort on the other hand. A symmetry reduction approach is then discussed to reduce the computational burden of this sampling algorithm.