High-power UV-LED degradation: Continuous and cycled working condition influence

Abstract

High-power (HP) UV-LEDs can replace UV lamps for real-time fluoro-sensing applications by allowing portable and autonomous systems. However, HP UV-LEDs are not a mature technology, and there are still open issues regarding their performance evolution over time. This paper presents a reliability study of 3 W UV-LEDs, with special focus on LED degradation for two working conditions: continuous and cycled (30 s ON and 30 s OFF). Accelerated Ufe tests are developed to evalúate the influence of temperature and electrical working conditions in high-power LEDs degradation, being the predominant failure mechanism the degradation of the package. An analysis that includes dynamic thermal and optical HP UV-LED measurements has been performed. Static thermal and stress simulation analysis with the finite element method (FEM) identifies the causes of package degradation. Accelerated Ufe test results prove that HP UV-LEDs working in cycled condition have a better performance than those working in continuous condition.

Functional Analysis in Long-Term Operation of High Power UV-LEDs in Continuous Fluoro-Sensing Systems for Hydrocarbon Pollution

“…The readout of the CCD micro-spectrometer has two components; reflected UV-LED signature and significant fluorescence signature. The UV-LED spectrum is represented in Figure 7 of [ 25 ], observing a very low optical power of UV-LED at wavelengths higher than 400 nm, for that, we considered the significant fluorescence signature in the range between 400 nm and 650 nm. Over 650 nm, the fluorescence signature CCD counts are near to zero.…”

“…Fluorescence detection systems based on compact CCD spectrometer are emerging as a tool in research field applications [ 2 , 3 , 4 , 20 ]. In this work two compact spectrometers (Avantes ® Ava-Spec 2048-USB2-UA, and Mightex ® HRS-BD1-025) have been used, the first one for workbench instrumentation in signature readout, and the second one for analysis of UV-LED temperature ALT [ 24 , 25 ]. The spectra readout is obtained via a specific optical fiber of 0.6 mm Ø, solid angle Ω = 0.15 sr, numerical aperture NA = 0.22 ( Figure 2 a).…”

“…The temperature ALT instrumentation is explained in [ 24 ] where the instrumentation and preliminary results of ALT are described. The HP UV-LEDs used their characteristics, and electrical and optical operational working conditions are exhaustively described in [ 25 ].…”

“…The future short-term objectives are recognition of the signature pattern and integration of the whole experimental system in automatic water quality station of the Jarama-Tagus Rivers (Spain) [ 22 , 23 ], working 24/7 ( Figure 1 ). In these automatic stations, the authors test different disciplines related to the development of new capabilities, such as the present work, which analyzes the HP UV-LED in the long-term, non-contact, continuous, real-time fluoro-sensing identification of the pollutants [ 20 , 24 , 25 ], as well as others, like the development of compact, low-power consumption high security warning communications systems with redundant dual-band based mobile phone systems (380 MHz and 960 MHz) [ 26 , 27 ].…”

Two optimized models of life prediction based on luminance degradation for VFD under a conventional life test

“…Accelerated stress tests shorten testing time by increasing test stress. Testing methods are mainly divided into two categories: accelerated life tests (ALTs) and accelerated degradation tests (ADTs) . Compared with the relatively mature ALTs, ADTs can detect the decaying process of product performance to provide more degradation information and predict life more precisely .…”