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

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.

Controlling the microstructure from the gold-tin reaction

“…The growths of Sn and In whiskers have been observed between laser and submount as a result of solder surface migration and electromigration. 2,3 Hard solders, including Au-rich Au-Sn, Au-Si, and Au-Ge alloys, have higher melting temperatures and higher yield strengths. Therefore, they are more resistant to creep.…”

Solder electromigration in Cu/In/Cu flip chip joint system

“…In the conventional electromigration experiments, In was transported toward the anode side and voids/hillocks nucleated at the cathode/anode, respectively [34,35,39]. In the surface electromigration experiments, it was reported that one mono layer of In moved on the surface toward the cathode while the anode side edge of In stayed when very thin In layer was fabricated on Si surface [36][37][38].…”

Advances in High-Power Laser Diode Packaging

“…However, this makes soft solder subject to thermal fatigue and creep rupture, causing long-term reliability problems (Solomon, 1986;Lau & Rice, 1985). They are also attributed to solder instabilities like whisker growth, void formation at the bonding part, and diffusion growth (Mizuishi et al, 1983(Mizuishi et al, , 1984Sabbag &McQueen, 1975 and obstruct its optical beam. As mentioned earlier, the laser diode package will experience elevated temperature during operation.…”