Hi Amol! There is a couple of public domain investigations that would be useful for component finishes. Celestica (Dr. P. Snugovsky et al), NIST (Dr. C. Handwerker et al), and Rockwell Collins (D. Hillman et al) have all published results of investigations demonstrating that if the bismuth content of a solder joint does not exceed 6 wt % then the impact on solder joint integrity is negligible. There is a common industry myth that the tin/lead/bismuth eutectic ternary phase will form causing the solder joint to melt during service thus impacting solder joint integrity. The published investigation results demonstrate the ternary phase does not form. Here are some useful references: [1] D. Hillman, ?Surface Mount Solder Joint Integrity Issues for Lead-free Soldering Concerning Lead and Bismuth Interactions?, National Physical Laboratory Lead-free Conference, June 22, 2006. [2] P. Snugovsky, et al, ?Solder Joint Formation with Sn/Ag/Cu and Sn/Pb Solderballs and Pastes?, SMTAI Conference Proceedings, 2002. [3] iNEMI consortia, iNEMI Recommendations on Lead-free Finishes for Components Used in High Reliability Products Report, Version 4 (12-1-06). [4] J. Lau and Y. Pao, Solder Joint Reliability of BGA, CSP, Flip Chip, and Fine Pitch SMT Assemblies, McGraw Hill, ISBN 0-07-036648-9. [5] P. Viswanadham and P. Singh, Failure Modes and Mechanisms in Electronic Packages, Chapman & Hall, ISBN 0-412-10591-8. [6] C. Coombs, Coomb?s Printed Circuits Handbook, Fifth Edition, McGraw Hill, ISBN 0-07-135016-0. [7] P. Snugovsky, et al, ?Microstructure and Properties of Sn-Pb Solder Joints with Sn-Bi Finished Components?, APEX Conference Proceedings, 2006. [8] K. Moon, et al, ?The Effect of Bi Contamination on the Solidification Behavior of Sn-Pb Solders?, Journal of Electronic Materials, Vol. 36, No. 6, pp. 676-681, June 2007. [9] C. Hunt and M. Wickham, ?Impact of Lead Contamination on Reliability of Lead-free Alloys?, APEX Conference proceedings, February 2006, Paper S39-01. [10] NEC Electronics, Lead-Free Semiconductor Products, NEC Pamphlet C14485EJ6V0PF00, March 2006. [11] M. Meilunas, et al, ?Alternative Lead Finish QFP Assembly and Lead Pull Study?, UIC Area Array Consortium Report, December 2004. [12] A. Syed, et al, Amkor TSOP-48 Internal Test Report, February 2002. [13] xxx [14] J. Clech, et al, ?A Comprehensive Surface Mount Reliability Model Covering Several Generations of Packaging and Assembly Technology?, IEEE Transactions On components, Hybrids and Manufacturing Technology, Vol. 16, No. 8, December 1993, pages 949-960. [15] G. Gaylon, ?Annotated Tin Whisker Bibliography and Anthology?, iNEMI consortia monograph, Version 1.2, 2003. [16] GEIA-HB-0005-2, Technical Guidelines for Aerospace and High Performance Electronic Systems Containing Lead-free Solder. The SMTAI 2007 Proceedings contains the Rockwell Collins paper with this reference list. As far as the use of a SnBi solder alloy, you are going to exceed the 6wt% maximum value and if there is lead present in the process (pwb pads, lead finishes, etc.) then you are going to have an issue with the ternary alloy. One published case is this reference were a SnBi solder alloy and component with a tin/lead finish resulted in significant solder joint issues. D. Hillman et al, ?JCAA/JGPP No-Lead Solder Project: -55C to +125C Thermal Cycle Testing Final Report?, SMTAI Conference Proceedings 2006 Good Luck. Dave Hillman Rockwell Collins [log in to unmask] "Kane, Amol (349)" <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 10/07/2008 10:56 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to "Kane, Amol (349)" <[log in to unmask]> To [log in to unmask] cc Subject [TN] Sn-Bi Alloy for soldering Does anybody have any experience with Sn-Bi alloy used for soldering lead-free boards? I am looking at literature available out there and see Sn-Bi used as a surface finish for components, but I have not yet found a reference where it is used for soldering. Looking for pros/cons, good/bad experiences and things to look out for during soldering. The application is all SMT, with a temp sensitive part. The manufacturer therefore wants to use Sn-Bi alloy as this is a lower melting point alloy Regards, Amol WARNING: Export Control This document may contain technical data within the definition of the International Traffic in Arms Regulations (ITAR), and subject to the Export Control Laws of the U.S. Government. Transfer of such data by any means to a foreign person, whether in the United States or abroad, without proper export authorization or other approval from the U.S. Department of State is prohibited. CONFIDENTIALITY NOTICE: This e-mail, and any attachments, is for the sole use of the intended recipient(s) and may contain information that is confidential and protected from disclosure under the law. Any unauthorized review, use, disclosure, or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail, and delete/destroy all copies of the original message and attachments. 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