ENHANCED PROCESSABILITY AND THERMAL FATIGUE RELIABILITY WITH LOW MELTING POINT SNBI SOLDER ALLOY LMPA-Q

Abstract

SnBi based solder alloys become an interesting alternative for standard SnAgCu as they can be used to solder components at much lower temperature. The typically 50 degrees C lower solder reflow temperature is less damaging for PCB and components, and also prevents hot tear and head-in-pillow failures for large fine pitch BGA components. A reasonable concern for these low-melting temperature solders is the thermal cycling reliability performance, in particular for harsh conditions such as automotive products. In this work, thermal cycling testing and failure analysis have been performed on 9x9 mm size QFN components and large chip components (2010 and 2512) which are typically sensitive to thermal fatigue. The results are benchmarked to standard SAC alloy. Also the process advantages from the low temperature solder alloys are depicted in this paper. Finally, the effect of Pb contamination on this SnBi based solder is investigated.