This document specifies thermal testing procedures for power light-emitting diodes (power LEDs) and/or high brightness light-emitting diodes (HB LEDs) – in the following referred to as LEDs – which are typically used in the operating regime of the forward current of 100mA and above, and emit visible light1). The application of these measurement guidelines is recommended for packaged LEDs:
- with a total electrical power consumption above 0.5 W,
- which have energy conversion efficiency above 5%, and
- that are powered by steady DC power (typically with forced constant forward current), regardless whether the LED device inside the package is realized as single chip or multi chip device.

Further details of the definition of term LED or LED device used in this document are given in 0. This document does not deal with laser diodes.

When speaking about thermal testing, one can distinguish between laboratory testing and bulk testing. The scope of this document is laboratory testing of power LEDs.

Recommendations given in this document are valid for both steady-state and dynamic (transient) thermal measurements of LEDs, both relying on JEDEC JESD51-, Electrical test method. For steady-state thermal metrics both the static and dynamic test methods defined in JESD51-1 can be used.

Regarding the heating power, this document is aimed as an LED specific extension of the JEDEC JESD51-14, Transient Dual Interface Test Method for the Measurement of Thermal Resistance Junction-to-Case of Semiconductor Devices with Heat Flow through a Single Path document, applicable for DC driven LEDs only. Further LED specific additions to JESD51-14 may also be published in the future which would deal with practical aspects of the differences between power LED packages and other power semiconductor device packages.