Observation of highly durable silicone resin for encapsulating algan‐based uvb light‐emitting diodes

Mu Jen Lai, Rui Sen Liu, Tsung Yen Liu, Shih Ming Huang, Ray Ming Lin*, Yi Tsung Chang, Jian Bin Wu, Wen Hong Sun, Xiong Zhang, Lung Chien Chen*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

1 Scopus citations


In this paper, we report an AlN‐based ceramic lead frame (LF) with encapsulating silicone between the surface of an AlGaN‐based ultraviolet‐B light‐emitting diode (UVB‐LED) chip and a quartz glass cover; the light output power (LOP) of this structure was 13.8% greater than that of the corresponding packaging structure without encapsulating silicone. Another packaging structure in which the silicone fully filled the cavity of the AlN‐based ceramic LF included covering with quartz glass; in this case, the enhancement of the LOP was 11.7%. Reliability tests performed over a period of 3500 h at a forward current (If) of 100 mA revealed that the LOPs of these two silicone‐containing packaging types decreased to 45.3 and 48.6%, respectively, of their initial values. The different degradation rates of these UVB‐LEDs were not, however, correlated with the appearance of cracks in the encapsulating silicone during long‐term operation. Excluding any possible mechanisms responsible for degradation within the UVB‐LED chips, we suggest that the hermetic cover should be removed to avoid the appearance of cracks. Moreover, the main mechanism responsible for the slow degradation rates of LOPs in these proposed packaging structures involves the encapsulated silicone, after cracks have appeared, undergoing further deterioration by the UVB irradiation.

Original languageEnglish
Article number9278
JournalApplied Sciences (Switzerland)
Issue number19
StatePublished - 01 10 2021

Bibliographical note

Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.


  • AlGaN
  • Degradation
  • Encapsulation
  • Light emitting diodes
  • Package
  • Silicone
  • Ultraviolet


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