Influence of phosphor configuration on thermal performance of high power white LED array

Abstract

Thermal management is of critical importance for high power white light-emitting diodes lamps in which blue chip array is combined with yellow phosphors. In this study, the thermal performance of a 100W white LED package on a heat sink with a CCT of 4500K under different phosphor configuration was investigated by a combination of the ray-tracing simulation and computational fluid dynamics simulation. Key simulation results were verified by experiment at first. The simulation results show that the maximum temperature of the model always exists in the phosphor layer. As phosphors are moved away from the LED chips, the maximum temperature of phosphors increases from 120.4°C (200-μm thick conformal phosphor coating) to 160.6°C (in-cup phosphor), and even to 203°C (200-μm thick remote phosphor). It coincides with an analysis of the thermal resistance network of the model, which shows that the major dissipation path for heat generated in the phosphor layer is through the (encapsulant) chips, substrate, heat sink into the air. Among all studied phosphor configurations, the highest junction temperature is 98.3°C, and exists in the model with conformal phosphor coating. It is due to severe absorption of back scattered light by LED chips with phosphor coating.