Some aspects of bonding-solder deterioration observed in long-lived semiconductor lasers: Solder migration and whisker growth

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Abstract
This paper reports on catastrophic degradation, called sudden failure (SF), that is observed in both AlGaAs/GaAs and InGaAsP/InP double-heterostructure lasers. The SF observed here is not associated with electrical surge effects and appears unexpectedly in the middle of a long-term, stable operation. It was found that this type of SF can be caused by aging-induced metallurgical deterioration at the interfacial bonding solder layer. Among the metallurgical deteriorations observed were (1) solder migration into the laser crystal due to current-induced local heating near the end mirror of the laser, (2) In whisker growth due to electromigration in In solder, and (3) Sn whisker growth, when using an Au-Sn alloy as solder, due to strain relaxation. All of these effects cause SF. Countermeasures against these deteriorations are described and some successful results are presented.