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NEMI Lead-Free Assembly Project: Comparison Between PbSn and SnAgCu Reliability and Microstructures



C A. Handwerker, J Bath, E -. Benedetto, E -. Bradley, R -. Gedney, Thomas A. Siewert, P Snugovsky, J -. Sohn


The National Electronics Manufacturing Initiative (NEMI) Lead-Free Assembly Project had the following priorities:--to down-select an alloy from the SnAgCu families to be recommended as the main standard lead-free solder;--to demonstrate production-ready parts, materials and processes for lead-free soldering printed wiring board (PWB) assemblies, with an eye to total lead elimination by 2004;--to cooperate with component, board and equipment manufacturers to allow for the smooth transition to components with higher exposure temperature limits of around 260 degrees C; and--to develop criteria for the industry to evaluate lead-free processes and reliability in order to assist industry with timely implementation of lead-free assemblies.This article presents qualitative thermal cycling results for all the components and alloy combinations tested and provides a quantitative comparison of the failure data and microstructures for the CSP169 components for NEMI tin-silver-copper alloy, eutectic tin-lead, and a mixed tin-silver-copper paste with Pb-containing surface finish.


failure analysis, lead free assembly, lead free solder, NEMI, solder joints, solder reliability


Handwerker, C. , Bath, J. , Benedetto, E. , Bradley, E. , Gedney, R. , Siewert, T. , Snugovsky, P. and Sohn, J. (2003), NEMI Lead-Free Assembly Project: Comparison Between PbSn and SnAgCu Reliability and Microstructures, SMTAI, [online], (Accessed May 21, 2024)


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Created November 1, 2003, Updated February 17, 2017