Comparison of two alternative junction temperature setting methods aimed for thermal and optical testing of high power LEDs

Bein, Marton C.; Hegedüs, János; Hantos, Gusztáv; Gaal, Lajos; Farkas, G.; Rencz, M.; Poppe, A.

doi:10.1109/therminic.2017.8233838

Cited by 18 publications

(9 citation statements)

References 3 publications

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“…During physical tests of LEDs, R thja is used in an iterative process to control T amb such that a target T J is reached. Thus, electric and radiometric properties can be measured at a programmed I F , T J operating point [31,32]. To obtain the thermal metrics, such as the junction-to-case thermal resistance (R thJC ), the applicable standard [33] prescribes thermal transient measurements at varying boundaries.…”

Section: Overall Considerations Regarding Multi-domain Chip Level Modmentioning

confidence: 99%

“…In all cases, we could observe the characteristic decay of the light output at high currents termed the "light droop". point [31,32]. To obtain the thermal metrics, such as the junction-to-case thermal resistance ( ), the applicable standard [33] prescribes thermal transient measurements at varying boundaries.…”

Section: Overall Considerations Regarding Multi-domain Chip Level Modmentioning

confidence: 99%

“…Five different color LED types were measured, using multiple numbers of samples from each type. To make the modelling easier, the cold plate control mode was set to regulate towards a fixed T J junction temperature as described in [31]. This ensured that the measured DC characteristics and the radiometric and photometric values corresponded exactly to the thermal boundary of a constant T J , without further model correcting steps.…”

Section: The Predictive Power Of the Physics Based Modelmentioning

confidence: 99%

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Multi-Domain Modelling of LEDs for Supporting Virtual Prototyping of Luminaires

et al. 2019

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This paper presents our approaches to chip level multi-domain LED (light emitting diode) modelling, targeting luminaire design in the Industry 4.0 era, to support virtual prototyping of LED luminaires through luminaire level multi-domain simulations. The primary goal of such virtual prototypes is to predict the light output characteristics of LED luminaires under different operating conditions. The key component in such digital twins of a luminaire is an appropriate multi-domain model for packaged LED devices that captures the electrical, thermal, and light output characteristics and their mutual dependence simultaneously and consistently. We developed two such models with this goal in mind that are presented in detail in this paper. The first model is a semi analytical, quasi black-box model that can be implemented on the basis of the built-in diode models of spice-like circuit simulators and a few added controlled sources. Our second presented model is derived from the physics of the operation of today’s power LEDs realized with multiple quantum well heterojunction structures. Both models have been implemented in the form of visual basic macros as well as circuit models suitable for usual spice circuit simulators. The primary test bench for the two circuit models was an LTspice simulation environment. Then, to support the design of different demonstrator luminaires of the Delphi4LED project, a spreadsheet application was developed, which ensured seamless integration of the two models with additional models representing the LED chips’ thermal environment in a luminaire. The usability of our proposed models is demonstrated by real design case studies during which simulated light output characteristics (such as hot lumens) were confirmed by luminaire level physical tests.

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Section: Overall Considerations Regarding Multi-domain Chip Level Modmentioning

confidence: 99%

Section: Overall Considerations Regarding Multi-domain Chip Level Modmentioning

confidence: 99%

Section: The Predictive Power Of the Physics Based Modelmentioning

confidence: 99%

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Multi-Domain Modelling of LEDs for Supporting Virtual Prototyping of Luminaires

et al. 2019

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“…When the electrical and light output characteristics are measured at a constant junction temperature, TJ, they are called iso-thermal IVL characteristics. The junction temperature of the LEDs can be set to a known value TJ by either of the methods recommended by CIE or JEDEC [Bein et al, 2017].…”

Section: Measurement Of Led Characteristicsmentioning

confidence: 99%

Does a Single Led Bin Really Represent a Single Led Type?

Mérelle¹,

Sari

Bucchianico

et al. 2019

PROCEEDINGS OF the 29th Quadrennial Session of the CIE

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In a recent H2020 European wide research project (Delphi4LED, www.delphi4LED.eu) extensive study for generating multi-domain compact LED models based on measurement data was concluded. In this context combination of the latest LED testing standards and recommendations of JEDEC and CIE have been applied in testing and new models and modelling methods have been developed in order to capture the multi -domain operation of LEDs for the purpose of simulation. A valid question is: how representative a model is for a type of an LED package, how to select a nominal LED device for modelling and how to capture the inherent variation of LED operating parameters. We had specific tasks dedicated to measure and model these variations. Findings related to capturing, quantif ying and modelling of the thermal features of the mechanical structure of LED packages have already been published. In this paper we report about the measured variances of the multi -domain chip level operation of LEDs and the way how to model them. During this analysis we were confronted with the issue of having various parameter distributions in a LED population purchased from the same bin. This raises the question: LEDs belonging to a given binning class really represents a single LED type if their multi -domain behaviour is different.

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“…This occurs at the combined thermal and radiometric and photometric measurements of high-power LED devices, where the optical characterization takes place in the thermal steady state at accurate junction temperature before initiating the cooling. The Rth thermal resistance of the assembly can be determined for this correction by transient measurements before starting the actual test [14]. In the case when an exact T J junction temperature has to be achieved at high heating current, a corrective step in the cold plate temperature regulation can be performed to reach precisely the target temperature.…”

Section: Errormentioning

confidence: 99%

Structural Analysis of Power Devices and Assemblies by Thermal Transient Measurements

2019

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Power modules composed of semiconductor dice, thermal interface layers, and cooling mounts can be characterized by thermal transient testing at their actual position (in situ). This paper demonstrates that transient testing enables tracking of changes in material quality and structural details on the raw heating or cooling curves. Higher precision can be achieved with the structure function technique where absolute and partial thermal resistance and capacitance values can be used for unambiguous identification of structural elements in a heat conducting path. Measurement techniques are presented to characterize the self-heating of a die and heat transfer between dice. Change of the thermal interface material layers in assembly during test sequences is also highlighted by the structure function concept. The power distribution between dice and wiring is analyzed by the newly introduced "accordion" principle.

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Comparison of two alternative junction temperature setting methods aimed for thermal and optical testing of high power LEDs

Cited by 18 publications

References 3 publications

Multi-Domain Modelling of LEDs for Supporting Virtual Prototyping of Luminaires

Multi-Domain Modelling of LEDs for Supporting Virtual Prototyping of Luminaires

Does a Single Led Bin Really Represent a Single Led Type?

Structural Analysis of Power Devices and Assemblies by Thermal Transient Measurements

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