DocumentCode :
3292758
Title :
Analysis of delamination and darkening in high power LED packaging
Author :
Zhou, Longzao ; An, Bing ; Wu, Yiping ; Liu, Shunhong
Author_Institution :
Wuhan Nat. Lab. for Optoelectron., Wuhan, China
fYear :
2009
fDate :
6-10 July 2009
Firstpage :
656
Lastpage :
660
Abstract :
Luminous emittance declination due to interfacial delamination and darkening is a fatal defect for the GaN-based high power light-emitting diodes (LEDs) under a long time service. This letter brought forward an accelerated aging test under 350 mA forward current, 25degC, 54% RH, 256 hours to testify and analysis the abnormal dark stain on the die surface of high power blue LEDs. SEM micrographs show that a delaminated layer exhibits between the die and the epoxy glue cap on the aging sample. EDAX results illuminates that the percentage of C and O elements is higher than normal. The thermal overstress on the epoxy along the interface owing to the high junction temperature is the main factor to degrade the epoxy gradually. As a result, a darkening area made up of carbon as well its oxide occurs on the LED die surface and depresses the luminous efficiency.
Keywords :
III-V semiconductors; X-ray chemical analysis; ageing; delamination; gallium compounds; life testing; light emitting diodes; scanning electron microscopy; wide band gap semiconductors; GaN; SEM micrographs; abnormal dark stain; accelerated aging test; current 350 mA; darkening; die surface; epoxy glue cap; fatal defect; high power LED packaging; interfacial delamination; light-emitting diodes; luminous efficiency; luminous emittance declination; thermal overstress; Accelerated aging; Delamination; Laboratories; Lead; Lenses; Light emitting diodes; Materials science and technology; Plastic packaging; Testing; Thermal degradation;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Physical and Failure Analysis of Integrated Circuits, 2009. IPFA 2009. 16th IEEE International Symposium on the
Conference_Location :
Suzhou, Jiangsu
ISSN :
1946-1542
Print_ISBN :
978-1-4244-3911-9
Electronic_ISBN :
1946-1542
Type :
conf
DOI :
10.1109/IPFA.2009.5232549
Filename :
5232549
Link To Document :
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