Experimental study of electroluminescence and temperature distribution in high-power AlGaInN LEDs &amp; LED arrays

Chernyakov, A. E.; Aladov, A. V.; Kalashnikov, Ivan A.; Закгейм, А. Л.; Смирнов, В.И.; Сергеев, В. А.

doi:10.1016/j.microrel.2017.04.035

“…. Q = hA (∆T) (2) In this equation, h is the convective coefficient. Both the coefficient and the thermal conductivity are non-material.…”

Section: Heat Convectionmentioning

confidence: 99%

“…With the physical model developed for the LED array, Chernyakov built an expression for the thermal resistance. Using optical microscopy and a thermographic camera, the relationship between thermal resistance and current was established by Chernyakov, and the actual temperature distribution was then obtained for the LED array [2]. Studies showed that the current density on the surface of the chip is critical for the performance of LEDs.…”

mentioning

confidence: 99%

Study on Thermoelectric Conversion and Conjugate Heat Transfer for PCBA by Finite Element Analysis

Lin

¹

,

Cheng

²

,

Zheng

³

et al. 2019

2019 IEEE International Conference on Computation, Communication and Engineering (ICCCE)

0

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In this study, the optical sphere and the power analyzer were exploited to measure the optical and power parameters for the high-power LED lamps. The results, derived from the experimental data, were used as the power distribution inputs in the finite element analysis (FEA) for the determination of the temperature distribution for the printed circuit board assembly (PCBA) built in the LED lamp. In the finite element analysis, the conjugate heat transfer model was adapted for the calculation of the heat transfer, including thermal conductivity, convection and radiation. Applied on the power chips located on the PCBA, the graphene thermal interface material (TIMs) had been studied for its effects on the temperature distribution. For an accurate simulation about the LED lamp, the model with closed and compact space was built in the analysis. Compared to the experimental data, it showed that the simulation results had a deviation in the range of 3-5% around the main heating source, the light-emitting diodes. It proves the FEA model proposed in this study were well developed for the simulation of the temperature distribution for the high-power LED lamps which have mixed heat transfer mechanisms. The thermal radiation effects by TIMs with graphene were also investigated in this study and proven to be useful for the heat dissipation for the LED lamps. power input is high and the volume of the VR device is small, cooling the power chips will be very difficult. Obviously, the traditional TIMs or grease is not enough for the cooling requirements for the up-to-date electronic devices. There should be new heat sinkers or dissipators which are able to solve the over-heat problems for the powerful and compact electronic devices.In this study, the conjugate heat transfer model provided by the commercial finite volume method (FVM) software, FLUENT, will be used for the analysis about the temperature distribution for the electronic devices with high-power chips and compact volumes, such as LEDs and VRs. The values of power for the dominant chips on the PCBA will be derived experimentally by the optical sphere and the power analyzer. In the FEA model, the power chips will be simulated as heat sources. Heat by conduction will pass through the printed circuit board from the power chips. On the boundary between the PCBA and air, heat transfer by convection will happen. In addition, when the power chips are applied with TIMs of graphene, the heat transfer by radiation will be introduced in the analytic model. Finite space will be constructed to simulate the cases for LED lights. The results of simulation will be verified by those data obtained by the experiments, which confirms the validity of the proposed FEA model. Literature ReviewThe parameters for the design of LED lights include luminous flux, chip temperature, input power and cooling mechanism, etc. An excessively high operating temperature will decrease the performance of LEDs. Generally, the higher the luminous flux is, the higher the operational temperature is. Precise measu...

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“…The light-emitting diode (LED), which is the most promising cold light source in the 21st century due to its energy-saving, environmental protection, high reliability, and flexible design qualities and other advantages, has been widely developed and applied in the field of lighting [1]. Furthermore, the flip-chip LED (FC-LED) filament, which is a new generation of LED lighting sources because of its flat coating technology, 360 • luminescence, no blue light, long life, and slow decay, is a popular choice among those who recall older forms of lighting.…”

Section: Introductionmentioning

confidence: 99%

Effect of Different Welding Methods on Flip-Chip LED (FC-LED) Filament Properties

Li

¹

,

Zou

²

,

Wu

³

et al. 2018

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This paper investigates the effect of two different welding methods, direct welding (DW) and vacuum furnace welding (VFW), on flip-chip light-emitting diode (FC-LED) filament properties. Shearing force, SEM, steady-state voltage, steady-state luminous flux, and change of photoelectric performance with aging time were employed to characterize the differences in filament properties between the two welding methods. The shearing test revealed that the average shearing force of the VFW group was higher than that of the DW group, but the two groups followed the standard. Furthermore, the microstructure of the VFW group fault was more smoother, and the voids were fewer and smaller based on the SEM test results. The steady-state voltage and luminous flux revealed that the VFW group had a more concentrated voltage and a higher luminous flux. The aging data revealed that the steady-state voltage change rate of both groups was not very different, and both luminous flux maintenance rates of the VFW group were higher than those of the DW group, but all were within the standard range. In conclusion, if there is a higher requirement for filament in a practical application, such as the filament is connected in series or in parallel and needs a higher luminous flux, it can be welded using vacuum furnace welding. If the focus is on production efficiency and the high performance of filaments is not required, direct welding can be used.

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Study on Thermoelectric Conversion and Conjugate Heat Transfer for PCBA by Finite Element Analysis

Lin

¹

,

Poon

²

,

Tu

³

et al. 2019

View full text Add to dashboard Cite

In this study, the optical sphere and the power analyzer were exploited to measure the optical and power parameters for the high-power LED lamps. The results, derived from the experimental data, were used as the power distribution inputs in the finite element analysis (FEA) for the determination of the temperature distribution for the printed circuit board assembly (PCBA) built in the LED lamp. In the finite element analysis, the conjugate heat transfer model was adapted for the calculation of the heat transfer, including thermal conductivity, convection and radiation. Applied on the power chips located on the PCBA, the graphene thermal interface material (TIMs) had been studied for its effects on the temperature distribution. For an accurate simulation about the LED lamp, the model with closed and compact space was built in the analysis. Compared to the experimental data, it showed that the simulation results had a deviation in the range of 3–5% around the main heating source, the light-emitting diodes. It proves the FEA model proposed in this study were well developed for the simulation of the temperature distribution for the high-power LED lamps which have mixed heat transfer mechanisms. The thermal radiation effects by TIMs with graphene were also investigated in this study and proven to be useful for the heat dissipation for the LED lamps.

show abstract

Experimental study of electroluminescence and temperature distribution in high-power AlGaInN LEDs & LED arrays

Cited by 3 publications

References 4 publications

Study on Thermoelectric Conversion and Conjugate Heat Transfer for PCBA by Finite Element Analysis

Study on Thermoelectric Conversion and Conjugate Heat Transfer for PCBA by Finite Element Analysis

Effect of Different Welding Methods on Flip-Chip LED (FC-LED) Filament Properties

Study on Thermoelectric Conversion and Conjugate Heat Transfer for PCBA by Finite Element Analysis

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