METHOD FOR PREDICTION OF RELIABILITY OF LEDS IN LIGHTING

Abstract

In LEDs reliability prediction, not considering the color shift could generate undesired results; however, in the literature it is not
frequent to find methods that consider this failure mode; and a great part of the existing methods do not integrate in the analysis
the factors of temperature and current jointly. In this work, a new method was developed to predict the LEDs reliability based on
the color shift, which takes into account the temperature and current. With the developed method, more reliability indicators,
such as reliability function, risk function and mean time to failure (MTTF), can be predicted in comparison with the IES TM-21-
11 and IES TM-35-19 methods. In addition, the models of several reliability indicators of a sample of NF2L757DR LEDs from
NICHIA CORPORATION are presented. The obtained graphs show that with increasing temperature and/or current, reliability
decreases.