Why is heat sinking important for LEDs?
It is common to refer to LEDs as “cool” sources in terms of temperature. This is because the spectral output of LEDs for lighting does not contain infrared radiation, unlike incandescent lamps that produce a large amount of infrared (of course, some LEDs for manufacturing purposes are designed to produce infrared energy, but these are not considered in this publication). LEDs are also often considered "cool" because they generate light through a mechanism other than thermal excitation of a substance, such as the tungsten filament in an incandescent lamp. Although LED lighting systems do not produce significant amounts of radiated heat, LEDs still generate heat within the junction, which must be dissipated by convection and conduction. Extracting heat from the device using heat sinks and by operating LEDs in lower ambient temperatures enables higher light output and longer life of the device.
The need to ensure heat sinking with LED systems is also important to consider when these systems are installed in applications. There must be sufficient means to conduct the heat away from the system, or ventilation to cool heated surfaces by convection. Locating an LED lighting system in an insulated and relatively small space will likely result in rapidly increased junction temperature and suboptimal performance.