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°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.It was experimentally found that the life time with this SnBi alloy was higher than with SAC alloy for these sensitive components. For some specific QFN component, the life time was even 5 times higher. This result sounds very promising for this solder alloy and may be a game-changer in future Pb-free soldering technology.The work is also supported by thermo-mechanical simulations using a creep model for the SnBi solder alloy.Finally, an experiment was done with a SnPb finished component to explore the impact of Pb contamination. There were no earlier failures experienced in the thermal cycling testing, however, cross-sections showed a porous solder connection which probably makes the joint vulnerable to shock testing. It is clear that with this SnBi based solder alloy, Pb contamination must be avoided. &nbsp;

Enhanced Processability and Thermal Fatigue Reliability With Low Melting Point SnBi Solder Alloy LMPA-Q

Paper Proceedings: https://asmedigitalcollection.asme.org/InterPACK/InterPACK2021/volume/85505

ASME 2021 International Electronic Packaging Technical Conference and Exhibition (InterPACK2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.