ICSR (Soldering and Reliability) Conference Proceedings

Microstructure And Reliability Of Low Ag, Bi-Containing Solder Alloys

Authors: Eva Kosiba, Simin Bagheri, Polina Snugovsky, Ph.D., Doug Perovic, Ph.D.
Company: Celestica Inc., University of Toronto
Date Published: 5/14/2013   Conference: ICSR (Soldering and Reliability)

Abstract: Accelerated thermal cycling (ATC) was performed on a test vehicle which included various components, built with three low (or no) Ag, Bi-containing solders and compared to a baseline of SAC305 (Sn/Ag3%Cu 0.5%). Lead free SAC305 has become the default lead-free alloy for consumer electronic application use since the implementation of the RoHS legislation banning the use of Pb in solder. SAC305 however does not perform as well as SnPb in some key areas which are of importance to consumer electronic applications; specifically drop/shock performance and survival under accelerate thermal cycling conditions. Efforts have been made in the consumer sector to improve upon these properties of SAC305 by, for example reducing the amount of Ag in order to improve drop/shock performance, however an alternate alloy is still required to meet all of the existing concerns. It has been shown in the previous paper presented at last year’s ICSR conference “Assembly Feasibility and Property Evaluation of Low Ag, Bi-Containing Solder Alloys” that these alloys show promise in drop/shock performance. This work shows that these same Bi-containing ternary and quaternary alloys also show promise in ATC. ATC of 3000 cycles was performed from 0C to 100?C. The results of the three Bi containing alloys were compared to SAC305. Additionally microstructural evaluation was performed at time zero and after ATC. Bi containing solders may prove to be adequate replacement for SAC305 in consumer electronic applications.

Key Words: 

Lower Melt Pb-free solder, Bi-containing alloys, Accelerated Thermal Cycling

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