Lu Guoguang

The relationship between LED package and reliability

Package is a key factor, and affects the reliability of LED. In this paper, the main failure modes and mechanisms that caused by poor package process were investigated through some failure analysis cases, and some improving methods to improve the LEDs reliability are put forward.

Prognostics and health monitoring of LED lighting system

Health monitoring of LED lighting systems is necessary for some safety critical and emergency applications. Prognostics and health monitoring (PHM) is a method for anomaly detection and remaining useful life (RUL) prediction. In this paper, the LED lighting system was defined as LED lamp which is composed of LED strings and an electrical driver. This paper introduced different PHM approach. An implementation prognostics and health monitoring roadmap for LED lamp was then presented. The PoF-based method for evaluating the reliability of LED driver was also demonstrated. Finally, data driven approach was used to assess the reliability and predict the remaining useful lifetime of LED lamp based on the test data during the sustaining natural exposure test.

Reliability evaluation on high power light emitting diodes

In this paper, the main failure modes and mechanisms were investigated through some failure analysis cases, based on this, Subsequent 160°C, 170°C and180°C lifetime tests were completed. According to the method of least squares, the degradation model of high power light emitting diodes is obtained. Using the model and ALTA9 software, the extrapolated lifetime of high power light emitting diode at 25°C is 37718 hours. We also obtain an acceleration factor 70.5 of resulting in a thermal activation energy of Ea=0.35eV using Arrhenius function.

Mechanisms of high power laser diode

A fault tree of high power laser diode have been set up, include sudden failure mode, gradual degradation mode, open failure and short failure mode are analyzed in detail with several cases, some methods about improving the reliability of laser diode have been provided subsequently in this paper.

Studies of the degradation mechanisms in high power diode lasers

The main failure mechanisms of high power diode lasers such as material defects, mirror damage and solder related failures as well as to methods which significantly suppress the occurrence of catastrophic failure and solder related failures are investigated in this paper. Meanwhile, in order to obtain the lifetime data of high power QCM cm-bar arrays, we have set up an automated diode array reliability experiment to examine the characteristics of high power QCW cm-bar arrays over time, and aging test results up to 2.0×109 shots at 25°C will be reported.

Failure analysis of LEDs

Light-emitting diodes (LEDS) are a strong candidate for the nest-generation general illumination applications. The reliability of LEDs is the key point for its applications, and the main challenges facing the development of high reliable LED is packaging process. In this paper, the overview of state of the art techniques in LED failure analysis is provided, and the main failure modes such as bonding defects, die attaching defects and other defects that caused by poor package process are investigated through some failure analysis cases.

Reliability of high power QCW cm-bar arrays

We report here the lifetime testing of 10 high power cm-bar arrays using an automated diode array reliability experiment. The devices are tested at 25°C/100A, with a pulse width of 200µs and a duty factor of 2%. Most devices survive more than 1.0×109 shots. Failure analysis results on the few failing devices reveal failure modes of mechanical stress, chemical contamination and thermal migration.