This report provides a quantitative review of the thermo-mechanical properties of lead-free solders, with emphasis on Sn-Ag-Cu (SAC) and Sn-Ag alloys. The Sn-Ag-Cu alloys of near-eutectic composition are labeled "SAC" throughout the report, including the NEMI-selected Sn-3.9Ag-0.6Cu alloy. SAC solders are the alloys of choice for solder reflow assemblies. Eutectic SnAg is also recommended for wavesoldering applications. The microstructure of both alloys consists of a Sn matrix with finely dispersed intermetallic precipitates.This report starts with a review of SnPb properties and lessons learned from the development of constitutive and life prediction models for near-eutectic SnPb assemblies.The report then proceeds with the results of an extensive, although not exhaustive, review of material properties for SAC and SnAg alloys. Gaps in the material properties database are identified and suggestions are offered as to what additional testing and analysis are needed to develop constitutive models for engineering use.

LAST UPDATE: 2/10/2007

SOURCE: Clech, Jean Paul. "Review and Analysis of Lead-Free Solder Material Properties." National Institute of Standards and Technology. 29 March 2004. US Commerce Department. 17 Jan 2007

LINK: Review and Analysis of Lead-Free Solder Material Properties