Experimental analysis on estimating junction temperature and service life of high power LED array

• Published in: Microelectronics and reliability Vol. 120; p. 114121
• Main Authors: A., Rammohan, C., Ramesh Kumar, V.P., Chandramohan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2021
• Subjects: Arrhenius equation; Heat sink; High power LED; Light-emitting diode (LED); Service life of LED, failure prediction; Arrhenius equation; Light-emitting diode (LED); Service life of LED, failure prediction; High power LED; Heat sink
• ISSN: 0026-2714; 1872-941X
• DOI: 10.1016/j.microrel.2021.114121

Light Emitting Diode (LED) is mainly used in automotive vehicles and street light systems. The performance of a high power LED (HPLED) depends on its junction temperature (Tj). In this work, an attempt was made through an experimental study to estimate the service life of HPLED. For this purpose, an array of 77 W capacity HPLED was built on an aluminum heat sink. Thermocouples were used to measure the temperature on HPLED solder points (six points) and temperature on the heat sink (two points). The temperature, current and voltage values were measured using sensors and these values were taken as optimal reference values. Failure experiments were performed. Temperature and current were recorded and taken as failure reference values. These optimal and failure reference values were used to estimate the service life of HPLED. A real-time algorithm based on the Arrhenius model was used to monitor the failure of HPLED. It was found that at Tj of 25 °C, the lifetime of HPLED was 1.2 lakh h. The maximum Tj of HPLED was 125 °C and it was found that the lifetime was 4796 h at a maximum current of 0.45 A. It was concluded that, if HPLEDs were run with a safer Tj range of 45 to 65 °C, their service time was in the range of 65,000 to 20,000 h (approx.). Uncertainty analysis was performed for all measured and estimated parameters. •A novel real-time algorithm based on the Arrhenius model was developed to estimate the service life of HPLED.•The junction temperature (Tj) was estimated using solder point temperature, forward voltage and thermal resistance.•The maximum Tj of HPLED was 125 ºC and the lifetime was 4796 h at a maximum current of 0.45 A.•At Tj range of 45 to 65 °C, their service time was in the range of 65,000 to 20,000 h (approx.).