Analysis of thermal characteristics and mechanism of degradation of flip-chip high power LEDs

Chien Ping Wang, Tzung Te Chen, Han Kuei Fu, Tien Li Chang*, Pei Ting Chou, Mu Tao Chu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)


The purpose of this study is to investigate the thermal behavior at the die-attached interfaces of flip-chip GaN high-power light emitting diodes (LEDs) using a combination of theoretical and experimental analyses. The results indicate that contact thermal resistance increased dramatically at the die-attached interfaces with aging time and stress, degrading the luminous flux. The junction temperature and thermal uniformity of the flip-chip structure both strongly depend on the arrangement of gold bumps. Local hot spots effectively reduce light output under high electric and thermal stress, influencing the long-term performance of the LED device. The results were validated using finite element analysis and in experiments using an infrared and an emission microscope. A two-step thermal transient degradation mode was identified under various aging stresses. A simulation further optimized the bump configuration that was associated to yield a low junction temperature and high temperature uniformity of the LED chip. Accordingly, the results are helpful in enhancing the performance and reliability of high-power LEDs.

Original languageEnglish
Pages (from-to)698-703
Number of pages6
JournalMicroelectronics Reliability
Issue number4
Publication statusPublished - 2012 Apr

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Safety, Risk, Reliability and Quality
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering


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