Thermal analysis and optimization of multiple LED packaging based on a general analytical solution

Multiple-chip packaging becomes common in LEDs packaging community. For such type of packaging, thermal spreading resistance is an important factor to affect the total thermal performance of LEDs. In this study, a general analytical solution is used to study the whole temperature field of LED packaging substrate, this solution is based on the method of variable separation for thermal spreading resistances of eccentric heat sources on a rectangular flux channel. The feasibility of the analytical method used in LEDs packaging has been proven by the temperature comparison with existing experimental and numerical results of an 80 W LED street lamp. By changing the chips arrangement on the substrate, temperature field optimization is conducted with maximal temperature difference of the substrate as the target function. The results show that spreading resistance plays a significant role to affect temperature field. When the LED distributions are effectively designed, the highest temperature on the substrate goes lower and the lowest temperature on the board goes higher, the temperature field becomes uniform, its spreading resistance becomes lower.