Thermal/luminescence characterization and degradation mechanism analysis on phosphor-converted white LED chip scale packages

Jiajie Fan, Chaohua Yu, Cheng Qian, Xuejun Fan, Guoqi Zhang

Research output: Contribution to journalArticleScientificpeer-review

14 Citations (Scopus)

Abstract

According to the requirements on minimizing the package size, guaranteeing the performance uniformity and improving the manufacturing efficiency in LEDs, a Chip Scale Packaging (CSP) technology has been developed to produce white LED chips by impressing a thin phosphor film on LED blue chips. In this paper, we prepared two types of phosphor-converted white LED CSPs with high color rendering index (CRI > 80, CCT ~ 3000 K and 5000 K) by using two mixed multicolor phosphor materials. Then, a series of testing and simulations were conducted to characterize both short- and long-term performance of prepared samples. A thermal analysis through both IR thermometry and electrical measurements and thermal simulation were conducted first to evaluate chip-on-board heat dissipation performance. Next, the luminescence mechanism of multicolor phosphor mixtures was studied with the spectral power distribution (SPD) simulation and near-field optical measurement. Finally, the extracted features of SPDs and electrical current-output power (I-P) curves measured before and after a long-term high temperature accelerated aging test were applied to analyze the degradation mechanisms. The results of this study show that: 1) The thermal management for prepared CSP samples provides a safe usage condition for packaging materials at ambient temperature; 2) The Mie theory with Monte-Carlo ray-tracing simulation can be used to simulate the SPD of Pc-white LEDs with mixed multicolor phosphors; 3) The degradation mechanisms of Pc-white LEDs can be determined by analyzing the extracted features of SPDs collected after aging.
Original languageEnglish
Pages (from-to)179-185
Number of pages7
JournalMicroelectronics Reliability
Volume74
DOIs
Publication statusPublished - 2017

Keywords

  • Phosphor-converted white LED
  • Chip scale packages
  • Multicolor phosphors
  • Thermal/luminescence characterization
  • Degradation mechanisms

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