Building-in reliability for silver die attached light emitting diodes

Abstract

In this paper, we present a failure analysis and reliability case history of light emitting diodes (LEDs), used in a fibre optics transmitter product, bonded using silver die attach epoxy. The observed failure mode was a reduction in light output of the transmitter device due to increased forward voltage after pulsed, high current operation which was attributed to the electrical degradation of the silver die attach epoxy. Steps taken to design in reliability into the product involved experimental design to optimize the die attach process, evaluation of more robust epoxies which can withstand accelerated high temperature and high current burn-in conditions, and the use of an improved die back-contact metallization system. Reliability performance of the die attach system was predicted and extrapolated to actual field application and burn-in conditions. © 1994.