Overdriving reliability of chip scale packaged LEDs
Quantitatively analyzing the impact of component
Hongyu Tang (TU Delft - Electronic Components, Technology and Materials, Changzhou Institute of Technology Research for Solid State Lighting)
Huaiyu Ye (Chongqing University)
Cell K.Y. Wong (Changzhou Institute of Technology Research for Solid State Lighting)
Stanley Y.Y. Leung (Changzhou Institute of Technology Research for Solid State Lighting)
Jiajie Fan (Hohai University, Changzhou Institute of Technology Research for Solid State Lighting)
Xianping Chen (Chongqing University)
Xuejun Fan (Lamar University)
Guoqi Zhang (TU Delft - Electronic Components, Technology and Materials)
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Abstract
The objective of this study is to quantitatively evaluate the impacts of LED components on the overdriving reliability of high power white LED chip scale packages (CSPs). The reliability tests under room temperature are conducted over 1000 h in this study on CSP LEDs with overdriving currents. A novel method is proposed to investigate the impact of various components, including blue die, phosphor layer, and substrate, on the lumen depreciation of CSP LEDs after aging test. The electro-optical measurement results show that the overdriving current can lead to both massive light output degradation and significant color shift of CSP LEDs. The quantitative analysis results show that the phosphor layer is the major contributor to the failure in early period aging test. For the long-term reliability, the degradations of phosphor and reflectivity of substrate contribute significantly on lumen depreciation. The proposed reliability assessment method with overdriving loadings can be usefully implemented for LED manufacturers to make a cost- and effective-decision before mass production.
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