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

Abstract

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 °C and 110 °C 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 °C) was found to be 55.72 °C. Finally the 70% luminary life time of 1-W HBLEDs under these conditions was found to be 8,344 hours.

Review—Reliability and Degradation Mechanisms of Deep UV AlGaN LEDs

“…As an example, Wang et al 173 reported a model in which the where A Tj and Ɵ are constants derived from a weighting of temperature and current-driven stress. Yang et al 172 reported an alternative model, developed for white LEDs, which again assumed junction temperature and drive current were the dominant factors, but used multiple-coupled stress ageing rather than constant stress conditions., i.e. different currents at the same temperature and different currents at different temperatures.…”

“…However, it does provide a reasonable fit to experimental data for white LEDs. 172 Zhang et al 48 made a quick assessment of the lifetime of transparent UV LEDs employing a p-AlN contact layer LED, through fitting of its EQE-J curves before and after short-term reliability test.…”

A Review of Prognostic Techniques for High-Power White LEDs

“…The models proposed in this work can be used to model and predict long-term lumen maintenance (reliability) of LED arrays by using IES-LM-80 test data of single LEDs. Edirisinghe et al [161] used an Arrhenius accelerated life test model with the modeling parameter as the junction temperature in the determination of the useful lifetime of 1-W HBLEDs (high-bright light-emitting diodes). However, the proposed PoF models are too general, and they do not provide details about the various failure/degradation mechanisms for LEDs.…”