LED performance is strongly influenced by the junction temperature. That is, LEDs'
dissipation, the package thermal resistance (or impedance) and thermal environment
(including ambient temperature and actual cooling conditions) are key parameters from
the point of view of LED operation both at end-users in the field and during laboratory
and production testing. To predict LED operation in a final application requires proper
characterization of the LEDs.
Though there have been great efforts in standardization of SSL products, until recently
thermal aspects remained step children – except prescribing elevated aging temperatures
during LM80 lifetime tests. The importance of the thermal issues and the need for
new, LED specific thermal testing standards has been acknowledged by some vendors
who were the first to invest into the new thermal testing technologies and started
pursuing thermal standardization activities.
The JEDEC JC15 committee was among the first to act in 2009 by setting up a LED thermal
testing task group, followed by the Division 2 of CIE where different technical committees
have been set up to complete LED testing standards with thermal aspects. This talk
aims at providing the latest news about the activities in these committees with a
main focus on the new JEDEC JESD51-50 series of standards on LED thermal testing (published
in April 2012):
• JESD51-50 – overview document of thermal testing of high power LEDs
• JESD51-51 – guidelines about the application of the electrical test method for high
• JESD51-52 – guidelines how to apply the CIE 127-2007 total flux measurement methods
in connection with thermal testing of high power LEDs;
• JESD51-53 – glossary, terms and definitions in relation to thermal testing of high
Furthermore, the talk aims to briefly introduce how the above characterization techniques
provide real thermal metrics of LED devices together with their hot lumens and temperature
dependence of their luminous flux and other light output properties.