Impact of Die Carrier on Reliability of Power LEDs

Kyatam, Shusmitha; Alves, Luís Nero; Maslovski, Stanislav I.; Mendes, Joana Catarina

doi:10.1109/jeds.2021.3115027

Cited by 5 publications

(8 citation statements)

References 37 publications

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“…The cross-section view of an individual LED is shown in Figure 1A. 25 The LED die (in blue color) is composed by a silicon carbide (SiC) substrate 26 on which the gallium nitride (GaN) active layers 27 were deposited. The LED die is attached to an AlN carrier (in gray); the LED junction terminals and the electrodes deposited on the top surface of the carrier are electrically connected via wire bonds (red shapes).…”

Section: Methodsmentioning

confidence: 99%

“…Using this setup, the thermal pad temperature was measured as a response to current steps between 100 and 700 mA (and a step of 100 mA) and to a 350 mA current step (nominal current). The thermal pad temperature and the LED voltage were also measured as a response to triangular current waveforms with a peak value of 700 mA and varying step rates (5,8,10,20,25,50,80,100,150,200,300, and 500 mA/s) corresponding to sweeping frequencies between…”

Section: Methodsmentioning

confidence: 99%

“…The LEDs have a small footprint (

2.45 \times 2.45

mm 2 ) and a maximum current rating of 1 A. The cross‐section view of an individual LED is shown in Figure 1A 25 . The LED die (in blue color) is composed by a silicon carbide (SiC) substrate 26 on which the gallium nitride (GaN) active layers 27 were deposited.…”

Section: Methodsmentioning

confidence: 99%

“…(A) LED cross‐section view (drawing not to scale) (reprinted from Kyatam et al 25 ; permission conveyed through CCBY 4.0: https://creativecommons.org/licenses/by/4.0/). LED mounted on (B) PCB and (C) diamond boards.…”

Section: Methodsmentioning

confidence: 99%

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Modeling temperature dynamic effects for high‐power light‐emitting diodes

Kyatam

Rodrigues

Alves

et al. 2022

Circuit Theory & Apps

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Temperature is a dynamic variable in most electronic devices. As the device operates, it generates heat, which translates in a temperature increase. Available models commonly disregard these variations due to the fact that they manifest at very large time scales. However, temperature dynamic effects have profound implications on the device model and on our common understanding. This paper discusses implications of considering the temperature variations on the current-voltage characteristic curves of power light-emitting diodes. The main theoretical results establish that the current equation has a memristive nature when temperature is assumed as a dynamical state variable. This hypothesis is then validated experimentally. K E Y W O R D SDC characteristic, hysteresis, memristor, power diode, power LED, thermo-electrical diode model | INTRODUCTIONStandard thermal analysis of power electronic circuits usually assumes static temperature conditions, that is, temperature evolution is considered a very slow process when compared to the operating frequencies. Under this simplifying assumption (and assuming one can neglect the transfer of heat through radiation and convection), the thermal analysis of a given circuit follows straightforward Ohm's law-like relations, where temperature increases linearly with the dissipated power with a slope equal to the thermal resistance of the device. 1 This simple relation is the basis of conventional heat sink (HS) selection procedures, where a series of multiple thermal resistances account for the heat conduction from the device's active region, where it is generated, to the environment, where it is dissipated.Temperature is also a parameter that influences the device's characteristics. Current-voltage relations in diodes and transistors involve temperature in multiple instances: (i) the thermal voltage k B T=q (where k B is the Boltzmann constant and q is the charge of the electron) increases linearly with temperature; (ii) carrier concentrations follow Fermi-Dirac distributions, which are strongly affected by temperature; and (iii) material properties such as thermal conductivity vary with temperature. 2 These temperature-dependent device's current-voltage relations are generally oversimplified and mistreated in the available literature. For instance, it is a common procedure to depict the temperature dependence of the diode current-voltage relation as a collection of curves obtained for different fixed temperature

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…The LEDs have a small footprint (

2.45 \times 2.45

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Modeling temperature dynamic effects for high‐power light‐emitting diodes

Kyatam

Rodrigues

Alves

et al. 2022

Circuit Theory & Apps

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the case of UV LEDs, this value is even higher [9][10][11]. The junction temperature of the LED chip affects optical and electrical performance, resulting in a drift of the wavelength which impacts on the reliability and productive life of the LED chip as key factors that determine ultimate application [12][13][14][15]. In improving the output power of the LED chip, it is essential that the thermal properties are enhanced to deliver optimum performance.…”

Section: Introductionmentioning

confidence: 99%

High Thermal Performance Ultraviolet (368 nm) AlGaN-Based Flip-Chip LEDs with an Optimized Structure

Sun,

Dong,

Luo

et al. 2024

Nanomaterials

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In this study, we have fabricated a 368 nm LED with an epitaxial Indium Tin Oxide (ITO) contact layer. We analyze the thermal performance of the flip-chip LED with a symmetric electrode and metal reflective layer, applying ANSYS to build a coupled electro-thermal finite element model (FEM) of the temperature distribution in the multiple quantum wells (MQWs). We compare our system with the traditional Au-bump flip-chip LED and a flip-chip LED with a Distributed Bragg Reflector (DBR) layer. The simulation results have shown that the flip-chip LED with a metal reflective layer and symmetric electrode exhibits better heat dissipation performance, particularly at high input power. The influence of the insulating layer on the LED chip junction temperature is also examined. The simulation data establish an effect due to the thermal conductivity of the insulating layer in terms of heat dissipation, but this effect is negligible at an insulation layer thickness ≤1 µm.

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