Influence of the Heat Sink Orientation and Fins Arrangement on the Thermal Behavior of High Power LED

Teeba Nadarajah,  Anithambigai Permal,  Dinash Kandasamy,  Mutharasu Devarajan

Nano Opto Electronics Lab (NOR), School of Physics, Universiti Sains Malaysia (USM), 11800 Minden, Penang, Malaysia


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 way to reduce the thermal effect on the LED packages at low cost.

In this study, horizontal and vertical finned heat sinks were used to investigate the thermal parameters such as thermal resistance and junction temperature using thermal transient measurement. The junction temperature reduces about 8˚C in vertical finned heat sink than in horizontal finned heat sink. Lower junction temperature induces for lower thermal resistance where the RthJA reduced from 25.7 K/W to 21.6 K/W. The need for an external heat sink was signified where the RthJA can reduce more than 50% when it is attached to the LED package. In addition, the horizontal and vertical orientation of the heat sink with the LED package was also studied. Lower RthJA was reported in the vertical position than in horizontal position. The higher thermal resistance in the horizontal position is due to the thermo-siphoning effect at the fins which reduces the overall heat dissipation efficiency.