Author
Tamdoğan, Enes, Pavlidis, G., Graham, S., Arık, Mehmet
Publication Date
2018-11
Publication Place
-
IEEE
Subject
Forward voltage, Infrared (IR) imaging, Light-emitting diode (LED) junction temperature measurement, Phosphor coating, Raman spectroscopy, RGB
Type
Periodical
Language
English
Digital
Yes
Manuscript
No
Library
Özyeğin University
Library Asset ID
2156-3950
Record ID
89eaa269-a992-48dd-921d-0dfe20a70d5d
Library Location
Mechanical Engineering
Date
2018-11
Notes
EU FP7 Career Integration ; Istanbul Development Agency
Sample Text
Energy efficiency, long life, exceptional color, and performance of solid-state light sources have resulted in a rapidly increasing trend in a number of practical applications especially for general lighting after a long history of incandescent lamps. Besides, light-emitting diodes (LEDs) have thermal limitations that are vital for device quality and lifetime. Specifically, to improve the heat dissipation, one major parameter used to evaluate the LED performance is thermal resistance (R). Reducing the resistance can improve the heat flow from the p-n junction to ambient during operation. To quantify this parameter, the LED junction temperature (TJ) must be determined. In this paper, the junction temperatures are first measured with forward voltage method (FVM), Raman spectroscopy, and infrared (IR) imaging for a 465-nm bare blue LED chip (without any phosphor coating). Then, the same samples have been coated with a phosphor-particles added epoxy mixture (%13, 4300 CCT) to convert blue to white light, and the junction temperatures were measured again experimentally with the previously mentioned three methods and compared to each other. While IR imaging shows better capability on capturing the possible hotspots over the surface, Raman method and FVM were in reasonably good agreement on measuring the junction temperature for 465-nm blue (uncoated) LED chip. However, the measurements performed after coating have shown slightly different results with IR imaging and Raman methods, while FVM has shown consistent results for coated chips.
DOI
10.1109/TCPMT.2018.2799488
Cilt
8
