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Heat management in Light Emitting Diodes (LED) is necessary to enhance its optical performance and stability. The usage of external heat sink is one of the efficient ways to reduce the thermal effect on the LED packages at low cost.

Proper heat management is necessary for better optical performance of high power light emitting diodes (LEDs). However, the thermal behavior of the LEDs differs as the chip technology changes. In this study, the InGaAlP and InGaN based amber and green LED were used to investigate the influence of different operating conditions on its thermal and optical performances. The increasing driving current affects the InGaN LED more than the InGaAlP LED. As the driving current increases, the green and amber LEDs loses its wall-plug efficiency (WPE) from 18.1 to 10% and 31.1 to 27.1% respectively. The higher drop in WPE of green LED was contributed by the higher junction temperature which rises more than 11.1°C than the amber LED. The RthJA was reduced around 4 K/W in green LED and only 1.9 K/W in the amber LED. However, the increasing ambient temperature give significant effect to the thermal behavior of the amber LED. As the ambient temperatures increases, the WPE of the amber LED reduces from 29.7 to 20.7% whereas the green LED loses its efficiency by 0.6%. By investigating the thermal and optical behaviors of the different chip LEDs under different operating conditions, the appropriate working condition of the LEDs at the optimum level can be identified.

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Proper heat management is necessary for better performance of the LEDs. In the present study, the thermo-optical properties of the LED with different type of PCBs were analyzed. The measurement was done with two different testing conditions to identify the effect of increasing drive current at constant ambient temperature and increasing ambient temperature at constant drive current on the the LEDs with different PCBs. In both the conditions, the thermal behaviors of the LED are affected much due to different type of boards. As the drive current increases, the junction temperature and RthJA of the LED with MCPCB reduces around 3.7K/W and 15.3K/W compare with the LED with FR4. The change in magnitude of chromaticity coordinates of LED with FR4PCB and MCPCB calculated as 0.154 and 0.132 respectively. At a lower ambient temperature, the LEDs with FR4 and MCPCB record the RthJA as 71.2K/W and 50.6K/W respectively. However, these values were lowered around 15% at higher ambient temperatures for both the LEDs. As ambient temperature increases, the shift in chromaticity coordinates for the LEDs with MCPCB and FR4 was obtained as 0.0163 and 0.0165. The influence of the different type of PCB’s performance on LEDs was observed in the increasing drive current condition rather than the increasing ambient temperatures.