Industries and Applications
LEDs revolutionized the lighting industry in the same way as semiconductor diodes and transistors changed the electronics industry: vacuum technology is replaced by semiconductor technology.
From a thermal perspective LED-based lighting systems are similar to electronic systems: high junction temperatures must be avoided in order to assure better performance and longer lifetime. Today further improvement of LEDs is hampered by the same limitation faced by the electronics industry: power densities resulting due to ever increasing demand for more and more luminous output can't be handled with traditional thermal management solutions.
LED thermal related problems are complex. This is due to the fact that their main function is not to rectify but to emit light – and all the properties of the emitted light depend on junction temperature. Moreover, self-heating of LEDs is also different than self-heating of conventional semiconductor devices.
TeraLED provides a unique, integrated solution to cope with all these issues. Combined with T3Ster technology, Mentor Graphics provides state-of-the-art realizations of the most recent thermal testing standards such as JEDEC JESD51-14 for general power semiconductor devices and JEDEC JESD51-15 and JESD51-52, thermal testing standards specific to power LEDs. The Mentor Graphics solution is unique because the T3Ster – TeraLED combination provides a direct link to FloTHERM and FloEFD for thermal simulation. LED models created from data obtained by T3Ster – TeraLED are completed with light output models and enable calculation of hot lumens in the FloEFD LED module. With this feedback between LED manufacturing and solid-state lighting product development, design cycles can be shorter and ultimately products can get to market faster.
Aerospace & Defense
LED lighting is becoming a standard in all new aircraft designs and flight instruments: the lower power consumption, better efficiency and higher lifetime expectancy provide greater reliability and competitiveness. Regardless of how thermal management is done, LED temperature and performance changes over its lifetime and understanding its performance helps the designer to choose the right LED for the task.
In such applications high reliability is critical for safety and keeping maintenance costs low. This detailed knowledge about LEDs and thermal interface materials used helps meet strict requirements for aerospace and defense applications.
- LED real thermal resistance according to JEDEC JESD51-51 standard is provided as a major design parameter
- Thermal transient measurement of LEDs followed by structure function analysis is the de facto standard for studying properties and aging of different thermal interfaces in situ
Automotive & Transport
Designing automotive luminaires is one of the toughest tasks: the complex geometry of luminaires must protect against harsh environmental conditions while providing proper thermal management for LEDs. In addition, the design should assure the highest possible reliability for the entire luminaire which is important both for safety and keeping car maintenance costs at a minimum.
Assuring the lowest possible junction-to-ambient thermal resistance is just one aspect of the design task. Selecting reliable LED products and being able to predict their hot lumens under actual operating conditions is another design aspect. Despite the existence of new LED specific thermal testing standards obtaining such information is not easy. Therefore, physical testing hardware such as Mentor’s T3Ster and TeraLED or simulation techniques for compact modeling of LEDs and hot lumen calculations embedded into FloEFD enable automotive luminaire designers to meet strict design requirements.
- Seamless, integrated workflow from comprehensive physical testing of LEDs including measurement of real thermal resistance and temperature dependence of light output properties through compact modeling of LED packages to CFD based thermal analysis of luminaires with hot lumen prediction
- Measurement of LED junction-to-case thermal resistance with the joint application of the JEDEC JESD51-14, 51-51 and 51-52 (CIE 1227:2007) standards
- Export LED package compact models from T3Ster Master and LED light output model from TeraLED View measurement results postprocessing tools for CFD simulation with FloEFD
Modern consumer goods such as TV sets and smartphones use LEDs. They are often densely packed. Aesthetics and thermal design requirements need to be met to ensure lifetime consumer expectations.
Therefore, thermal characterization at both component and system levels is as important as it is in other industrial sectors. Compact thermal modeling and model validation can be conducted with the T3Ster product family as well as Mentor CFD simulation solutions.
- Combination of T3Ster with TeraLED is ideal for comprehensive testing of LEDs used for flashlights or backlight units
- T3Ster measurements can be used to validate detailed CFD models of LED packages
- Compact models of LED packages with light output models are useful for designing e.g. large area LED-based displays with homogeneous luminosity – hot lumen calculations with FloEFD is an enabling technology for such applications. These models can be easily created with Mentor’s T3Ster and TeraLED family of hardware and software products
- T3Ster measurements followed by structure function analysis, a non-destructive method of failure analysis during and after LED lifetime tests (LM80 measurements), provide information about degradation of different thermal interfaces such as delamination of LED die-attach or solder to substrate such as an MCPCB
General Lighting and Streetlighting
General and streetlighting are popular applications for power LEDs. These applications can be harsh for LED lights as far as thermal conditions are concerned; for example, recessed downlights may have limited or blocked airflow around the luminaire and streetlights need to operate under hard environmental conditions while meeting strict lighting standards.
Therefore detailed knowledge about thermal properties and temperature dependence of the applied LEDs is a must. CFD analysis is widely used for luminaire-level design of such applications. Physical testing by combined use of Mentor’s T3Ster thermal transient tester and TeraLED LED light output measurement system can be used by appropriate dataprocessing results in LED models suitable for luminaire level thermal analysis.