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 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.

An Alternative Lifetime Model for White Light Emitting Diodes under Thermal–Electrical Stresses

“…Through the historical investigations on the degradation characteristics of LEDs, the accelerated loadings could be high temperature [ 22 ], high moisture [ 23 ], high driving current [ 24 ], a combination of temperature and moisture [ 25 , 26 ] or a combination of temperature with current [ 27 ]. Edirisinghe et al used a junction temperature based Arrhenius model to determine the lifetime of 1-W HBLEDs (high-bright light-emitting diodes) [ 28 ]. An accelerated aging test for high-power LEDs under different high-temperature stresses without input current was conducted in [ 29 ], which shows that a sufficiently high-temperature stress effectively shortens the unstable period of the LED chip.…”

An accelerated life evaluation method under multi-stress based on Eyring model

“…Its characteristic is accelerated stress may be temperature or a non-temperature factor.Literature [2] discusses the derivation of relationship between linear life dependence Arrhenius model and temperature in detail, the meaning of the activation energy and parameters B, which laid the foundation for wide application of Arrhenius model. Literature [3,4] studied the implementation of Arrhenius model in different product life assessment. Literature [5] discussed the life distributions of progressive stress accelerated life tests for Weibuil distributions under TFR model and gave the Bayesian estimates of the distribution parameters and coefficients in the inverse power law accelerated equation.…”