Accurate thermal transient measurements interpretation of monochromatic LEDs

In this work we determine the factors that influence the accuracy of LEDs thermal transient analysis, in particular, the leakage of heat into the dome material and the parasitic generation of heat on the reflector cup surface due to the light reflection losses are considered. Our analysis indicates a significant impact of these two factors on interpretation of the thermal transient measurements of mid-power LEDs. The paper demonstrates the significance of the physical phenomena behind these factors for creation of LEDs finiteelement thermal models. We quantify the inaccuracies in the thermal structure functions associated with these effects. We determine possible inaccuracies of finite-element models parameters calibration by thermal structure function or transient thermal response alignment if these factors are not accounted for. We show a substantial impact of the parasitic heat losses on the LEDs' reflector cup surface on the results of thermal transient for LEDs with high internal quantum efficiency encapsulated in packages with low light extraction efficiency.