Accelerated Life Test of High Brightness Light Emitting Diodes

Trevisanello, Lorenzo Roberto; Meneghini, Matteo; Mura, Giovanna; Vanzi, Massimo; Pavesi, M.; Meneghesso, G.; Zanoni, Enrico

doi:10.1109/tdmr.2008.919596

Cited by 147 publications

(52 citation statements)

References 13 publications

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“…Therefore, it is important to minimize the operating temperature of OLED panels in order to enhance device lifetime. The conventional method to determine the lifetime of OLEDs is accelerated lifetime testing (ALT) [23], which is also commonly used in other electronic devices, such as photovoltaic devices [24], and LEDs [25]. In this method, the lifetime at the targeted luminance level is extrapolated from lifetimes measured at higher luminance levels.…”

Section: Life Test Of Small Oled Pixelsmentioning

confidence: 99%

Thermal behavior and indirect life test of large-area OLED lighting panels

et al. 2014

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In this work, we studied the thermal behavior and addressed the challenges of life testing of large area OLED devices. In particular, we developed an indirect method to accurately calculate the life time of large-area OLED lighting panels without physically life-testing the panels. Using small area OLEDs with structures identical with the tested panels, we performed the life tests at desired driving current densities at different temperatures and extracted the relationship between junction temperature and the lifetime for the particular device. By measuring the panel junction temperature during operation under the same current density and using the life time measured on small area test devices, we determine the lifetime of the panels based on the thermal dependence. We test this methodology by predicting the life time of white PHOLED panels and then physically testing the panels. The typical result for the lifetime to 80% of the initial luminance (LT80) of the panel at a constant dc current density of 10 mA/cm 2 (3800 cd/m 2 ), was predicted to be 526 hours in good agreement with the actual life-test at 10 mA/cm 2 of 512 hrs. This good agreement, confirmed in different experiments, validates this novel technique as a practical life time predictor of large-area OLED lighting panels in a time saving manner.

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Section: Life Test Of Small Oled Pixelsmentioning

confidence: 99%

Thermal behavior and indirect life test of large-area OLED lighting panels

et al. 2014

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“…Increasing current generates more heat and induces worse electrical stress and thermal stress. This coupling effects of heat and current on the reliability of LEDs have been studied by many experiments [97][98][99][100][101][102][103][104]. The main impacts of high current and elevated temperature include increasing thermal resistance and forward voltage, reduction of thermal conductivity and transmittance of silicones and QE of phosphors, carbonization of packaging components and phosphors, wavelength shift of chip and phosphors, current crowding, and material degradation.…”

Section: Reliabilitymentioning

confidence: 99%

Status and prospects for phosphor-based white LED packaging

Liu

Wang

et al. 2009

Front. Optoelectron. China

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The status and prospects for high-power, phosphor-based white light-emitting diode (LED) packaging have been presented. A system view for packaging design is proposed to address packaging issues. Four aspects of packaging are reviewed: optical control, thermal management, reliability and cost. Phosphor materials play the most important role in light extraction and color control. The conformal coating method improves the spatial color distribution (SCD) of LEDs. High refractive index (RI) encapsulants with high transmittance and modified surface morphology can enhance light extraction. Multi-phosphor-based packaging can realize the control of correlated color temperature (CCT) with high color rendering index (CRI). Effective thermal management can dissipate heat rapidly and reduce thermal stress caused by the mismatch of the coefficient of thermal expansion (CTE). Chip-on-board (CoB) technology with a multilayer ceramic substrate is the most promising method for high-power LED packaging. Low junction temperature will improve the reliability and provide longer life. Advanced processes, precise fabrication and careful operation are essential for high reliability LEDs. Cost is one of the biggest obstacles for the penetration of white LEDs into the market for general illumination products. Mass production in terms of CoB, system in packaging (SiP), 3D packaging and wafer level packaging (WLP) can reduce the cost significantly, especially when chip cost is lowered by using a large wafer size.

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“…Out of many acceleration models, Arrhenius Acceleration Model has been chosen as the life time estimation model for this study, due to sample & facility constraints and according to the failure mechanism [1,4,[11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Arrhenius Accelerated Life Test for Luminary Life of High Bright Light Emitting Diodes

Edirisinghe

Rathnayake

2015

ILCPA

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The High Bright Light Emitting Diodes (HBLEDs) generally having long life but very often its actual life is different from vendor's specification. Vendors do not specify the failure criteria for their products but it may vary from 50% to 70% light output maintenance. Further time to test such a quantity takes too long under normal conditions. Longer time consumption for evaluation of such a quantity may not useful in mass production process of HBLEDs. The present study describes the determination of the useful lifetime of 1-W HBLEDs using Arrhenius Accelerated Life Test Model with the modeling parameter as the junction temperature. Failure criterion was chosen as 70% light output maintenance while two stress levels were selected as 90 ºC and 110 ºC and as recommended by IES LM-80-08 standard. Furthermore, forward voltage of the HBLED was used to determine junction temperature of the diode which is a critical parameter for this study. Moreover, junction temperature of the HBLED recognized as the most critical factor for degrades the lifespan. The Arrhenius Model is based on the junction temperature and activation energy parameters. The activation energy and the scaling factor were found to be 1.31 eV and 6.86×10 -17 hours respectively. HBLED junction temperature under room temperature (23 ºC) was found to be 55.72 ºC. Finally the 70% luminary life time of 1-W HBLEDs under these conditions was found to be 8,344 hours.

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Accelerated Life Test of High Brightness Light Emitting Diodes

Cited by 147 publications

References 13 publications

Thermal behavior and indirect life test of large-area OLED lighting panels

Thermal behavior and indirect life test of large-area OLED lighting panels

Status and prospects for phosphor-based white LED packaging

Arrhenius Accelerated Life Test for Luminary Life of High Bright Light Emitting Diodes

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