Reliability concerns and packaging issues of non-hermetic VCSEL and LED based transceivers for the enterprise market

In this paper we describe the lead frame based packaging technology used to produce both LED and VCSEL based transceivers. We review the issue of a nonhermetic environment and its effect on LED, PIN and VCSEL based structures. We show some of the distinct failure modes observed and present data on open lead frame assemblies that have been subjected to more than 6000 hours of 85°C/85% relative humidity (RH) testing, utilizing a silicone gel encapsulation process. The results show that the VCSEL structures, in a plastic packaged environment that is semi-hermetic, exhibit an infant mortality rate that is high and that a large number of catastrophic failures are observed within the first few hundred hours of testing. The application of the silicone gel environment eliminates the infant mortality failures and the VCSELs then exhibit typical wear out failure rates. We see that the failure in time (FIT) rate for the plastic package transceivers are typically <5000 FIT at 70°C, providing reasonable life times for bulk optic packages used in inter-office environments.