Reliability Estimation and Failure Analysis of LEDs with Various Currents and Correlated Color Temperatures for Identical Power Ratings: A Comparative Study.

LEDs are available in a variety of correlated color temperatures (CCTs) to suit specific application needs. Manufacturers also offer LEDs with varying power ranges, and identical power ratings but different voltage and current specifications. While consumers prioritize power ratings and CCT, the lack of reliability information in manufacturer specifications makes LED selection challenging. A comprehensive lifetime performance and reliability analysis is crucial to address this gap, aiding consumers in selecting suitable LEDs for luminaire design and helping manufacturers identify failure causes through physics of failure analysis. This study evaluates the reliability analysis of 3.84 W phosphor converted high-power LEDs with various CCTs (warm white and cool white) and with varying voltage/current rating parameters for the same power through accelerated testing in an environmental chamber. The SPD, photoluminescence, capacitance-voltage (C-V), and current-voltage (I-V) measurements are used to conduct additional physics of failure analysis. The analysis showed that WW LEDs decay faster in lumen performance compared to CW LEDs and chip degradation is the primary cause for the reduced light output in both WW and CW LEDs. Among the different specifications for the same power rating in WW and CW LEDs, the lumen performance is observed to be almost similar. But there is comparable difference in Duv in CW LEDs.