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.
International Letters of Chemistry, Physics and Astronomy (Volume 49)
M. Edirisinghe and P. Rathnayake, "Arrhenius Accelerated Life Test for Luminary Life of High Bright Light Emitting Diodes", International Letters of Chemistry, Physics and Astronomy, Vol. 49, pp. 48-59, 2015