Analysis on failure modes and mechanisms of LED
20 Jul 2009-pp 1237-1241
TL;DR: In this paper, the frequent failure modes and mechanisms such as chip failure and packaging failure were investigated through several failure analysis cases, and several methods to improve LED's reliability are reported in this paper.
Abstract: The reliability of LED is key to its application system. In this paper, the frequent failure modes and mechanisms such as chip failure and packaging failure were investigated through several failure analysis cases. Based on these analysis results, several methods to improve LED's reliability are reported in this paper.
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TL;DR: This paper provides the groundwork for an understanding of the reliability issues of LEDs across the supply chain and identifies the relationships between failure causes and their associated mechanisms, issues in thermal standardization, and critical areas of investigation and development in LED technology and reliability.
648 citations
TL;DR: In this article, the authors describe the healing behavior in structural and functional polymer composites with a so-called intrinsically self-healing polymer as the continuous matrix, which can ultimately lead to the design of polymeric composites that autonomously restore multiple properties using the same selfhealing mechanism.
Abstract: Self-healing is a smart and promising way to make materials more reliable and longer lasting. In the case of structural or functional composites based on a polymer matrix, very often mechanical damage in the polymer matrix or debonding at the matrix–filler interface is responsible for the decrease in intended properties. This review describes the healing behavior in structural and functional polymer composites with a so-called intrinsically self-healing polymer as the continuous matrix. A clear similarity in the healing of structural and functional properties is demonstrated which can ultimately lead to the design of polymer composites that autonomously restore multiple properties using the same self-healing mechanism.
166 citations
TL;DR: Self-healing concepts will be proposed to further improve LED’s reliability in order to increase reliability of SSL devices, components presenting self-repairing properties could be implemented.
112 citations
Cites background or methods from "Analysis on failure modes and mecha..."
...As an example, if the temperature of the device is too high, the encapsulant can reach its glass transition temperature and start to expand whereas other components will be less sensitive to this thermal expansion resulting in high mechanical stress in the epilayer and electrode bonding solders [147] and possible delamination between the encapsulant and the die [101,135,148,149]....
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...It magnitude is determined by the balance between heat generation (which is coupled to the intended light intensity of the device) and the thermal conduction [135]....
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...To reduce the density of dislocation, the use of a SiN/GaN buffer layer has been proposed [127,135]....
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TL;DR: Differences in the coefficient of thermal expansion between the molding part and the lens material as well as the heat generated by the phosphor layer are found to account for the major differences in the degradation mechanisms observed.
Abstract: A moisture- electrical – temperature (MET) test is proposed to evaluate the outdoor reliability of high power blue LEDs, with and without phosphor, and to understand the degradation physics of LEDs under the environment of combined humidity, temperature and electrical stresses. The blue LEDs with phosphor will be the high power white LEDs. Scanning acoustic microscopy is used to examine the resulted delamination during this test for the LEDs. The degradation mechanisms of blue LEDs (LEDs without phosphor) and white LEDs (LEDs with phosphor) are found to be different, under both the power on (i.e. with 350 mA through each LED) and power off (i.e. without current supply) conditions. Difference in the coefficient of thermal expansion between the molding part and the lens material as well as the heat generated by the phosphor layer are found to account for the major differences in the degradation mechanisms observed. The findings indicate that the proposed MET test is necessary for the LED industry in evaluating the reliability of LEDs under practical outdoor usage environment.
60 citations
01 Jan 2013
TL;DR: This chapter presents a definite, comprehensive and up-to-date guide to industry and academic research on LED failure mechanisms and reliability to help readers focus resources in an effective manner to assess and improve LED reliability for various current and future applications.
Abstract: The construction of LEDs is somewhat similar to microelectronics, but there are unique functional requirements, materials, and interfaces in LEDs that make their failure modes and mechanisms different. This chapter presents a definite, comprehensive and up-to-date guide to industry and academic research on LED failure mechanisms and reliability. It will help readers focus resources in an effective manner to assess and improve LED reliability for various current and future applications. In this review, we focus on the reliability of LEDs at the die and package levels. The reliability information provided by the LED manufacturers is not at a mature enough stage to be useful for the users of LEDs. This chapter provides groundwork for understanding of the reliability issues of LEDs. First, we present introduction about LED reliability and Physics of Failure (PoF) approach. We then categorize LED failures into 13 different groups related to semiconductor, interconnect, and package reliability issues. We close by identifying relationship between failure causes and associated mechanisms, issues in thermal standardization on LED reliability, critical areas of investigation, and development in LED technology and reliability.
30 citations
Cites background from "Analysis on failure modes and mecha..."
...The thermal expansion of the encapsulant pulls the wire bond from the surface of the die [75, 92, 124]....
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...The lifetime and performance of LEDs are limited by crystal defect formations in the epitaxial layer structure [73–76] of the die....
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...One possible solution is a correctly rated zener diode reverse biased in parallel with the LED [75, 130]....
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...The high electrical stress and extreme thermal shock are the causes of die cracking [15, 75, 79]....
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...Breakdown voltage and reverse saturation current are affected by contact material, thickness, defects in the substrate, and contamination [75, 123]....
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References
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Book•
18 Apr 2002
TL;DR: The history of all-solid-state lighting can be traced back to the early 1970s as mentioned in this paper, when the concept of white-light ledgers was introduced, and applications of Solid-State lighting were discussed.
Abstract: Preface. 1. Historical Introduction. 2. Vision, Photometry and Colorimetry. 3. Bulbs and Tubes. 4. Basics of All-Solid-State Lemps. 5. Light Extraction From Leds. 6. White Led. 7. Applications of Solid-State Lighting. References.
486 citations
Book•
01 Jan 1991
TL;DR: In this article, the degradation mechanisms and enhancement factors of AIGaAs/GaAs light sources reliability and degradation of InGaAsP/InP surface emitting type LEDs reliability in LEDs and laser diodes degradation of MBE-and MOVPE-grown lasers degradation of bonds and heat sinks degradation modes and lifetime of semiconductor LEDs and lasers
Abstract: Basics of semiconductor LEDs and lasers reliability in LEDs and lasers basic degradation mechanisms and enhancement factors reliability and degradation of AIGaAs/GaAs light sources reliability and degradation of InGaAs/InP surface emitting type LEDs reliability and degradation of InGaAsP/InP laser diodes degradation of MBE- and MOVPE-grown lasers degradation of bonds and heat sinks degradation modes and lifetime of semiconductor LEDs and lasers
383 citations
Additional excerpts
...This had been reported in many literatures [3]....
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08 Feb 2007
TL;DR: In this article, a current-accelerated method for fast estimation of the intensity and color degradation with corresponding variance of light-emitting diodes (LEDs) is presented.
Abstract: In this paper, a current-accelerated method for fast estimation of the intensity and color degradation with corresponding
variability of light-emitting diodes (LEDs) is presented The method is based on automated periodical spectral
measurements of emitted light of LEDs under different current loads, which include nominal and several different above
nominal currents The intensity and color degradation and corresponding variability among different LEDs at a specified
current are estimated by detailed analysis of the acquired spectral data at above nominal currents The method was
validated by comparing the predicted values with the measured values at nominal current The proposed method was
tested on white LEDs (luminous intensity ranged from 5 to 20 cd) from five manufacturers (Nichia, Etgtech, Sansen,
Daina, and Velleman) The results show that the intensity and color degradation and corresponding variability among
different LEDs is significant and, therefore, should be considered with great care when designing highly demanding
lighting products
4 citations
"Analysis on failure modes and mecha..." refers background in this paper
...Light emitting diodes (LEDs) offer a number of advantages over conventional light sources, such as reduced power consumption, better spectral purity, increased lifetime, faster response time, low driving voltage and lower costs, all of which are continuously improving [1]....
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01 Sep 2011
3 citations
"Analysis on failure modes and mecha..." refers methods in this paper
...We called the diode which produced by the electroluminescent principle as light emitting diode, commonly known as LED [2]....
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