Lumen depreciation is one of the major failure modes in light-emitting diode (LED) systems. It originates from the degradation of the different components within the system, including the chip, the driver, and the optical materials (i.e., phosphorous layer). The kinetics of degradation in real-life applications is relatively slow, and in most cases, it takes several years to see an obvious deterioration of optical properties. A highly accelerated stress testing (HAST) setup and a methodology to extrapolate the results to real applications are therefore needed to test the reliability of LED package and lens materials. Employing HAST concept in LED industry is inevitable due to the necessity of assessing the reliability of new products in a short period of time. This chapter aims at briefly explaining the degradation mechanism of optical components in LED package and how they contribute to the lumen depreciation of the LED package. The concept of HAST and the way the reliability of LED packages can be assessed will also be explained.
Original languageEnglish
Title of host publicationSolid State Lighting Reliability Part 2
Subtitle of host publicationComponents to Systems
EditorsWillem Dirk van Driel, Xuejun Fan, Guo Qi Zhang
Place of PublicationCham
PublisherSpringer International Publishing AG
Chapter5
Pages115-139
Number of pages25
Edition1
ISBN (Electronic)978-3-319-58175-0
ISBN (Print)978-3-319-58174-3
DOIs
Publication statusPublished - 2018

Publication series

NameSolid State Lighting Technology and Application Series
PublisherSpringer
Volume3
ISSN (Print)2196-4203
ISSN (Electronic)2196-4211

    Research areas

  • Encapsulants, Yellowing, Blue light exposure, Oxidation, Stress testing

ID: 31671791