Full Content is available to subscribers

Subscribe/Learn More  >

Material Behavior of Mixed Formulation Solder Joints

[+] Author Affiliations
Yifei Zhang, Kanth Kurumaddali, Jeffrey C. Suhling, Pradeep Lall, Michael J. Bozack

Auburn University, Auburn, AL

Paper No. InterPACK2009-89003, pp. 335-346; 12 pages
  • ASME 2009 InterPACK Conference collocated with the ASME 2009 Summer Heat Transfer Conference and the ASME 2009 3rd International Conference on Energy Sustainability
  • ASME 2009 InterPACK Conference, Volume 1
  • San Francisco, California, USA, July 19–23, 2009
  • Conference Sponsors: Electronic and Photonic Packaging Division
  • ISBN: 978-0-7918-4359-8 | eISBN: 978-0-7918-3851-8
  • Copyright © 2009 by ASME


The transition from tin-lead to lead free soldering in the electronics manufacturing industry has been in progress for the past 10 years. In the interim period before lead free assemblies are uniformly accepted, mixed formulation solder joints are becoming commonplace in electronic assemblies. For example, area array components (BGA/CSP) are frequently available only with lead free Sn-Ag-Cu (SAC) solder balls. Such parts are often assembled to printed circuit boards using traditional 63Sn-37Pb solder paste. The resulting solder joints contain unusual quaternary alloys of Sn, Ag, Cu, and Pb. In addition, the alloy composition can vary across the solder joint based on the paste to ball solder volumes and the reflow profile utilized. The mechanical and physical properties of such Sn-Ag-Cu-Pb alloys have not been explored extensively in the literature. In addition, the reliability of mixed formulation solder joints is poorly understood. In this work, we have explored the physical properties and mechanical behavior of mixed formulation solder materials. Seven different mixture ratios of 63Sn-37Pb and SAC305 solder materials have been formed, which include five carefully controlled mixtures of the two solder alloys (by weight percentage) and the two extreme cases (pure Sn-Pb and pure SAC). For the various percentage mixtures, the melting point, pasty range, stress-strain curves, mechanical properties (modulus, strength), and creep curves have been characterized. The variations of the mechanical properties and creep rates with aging at room temperature (25 °C) and elevated temperature (100 °C) have also been measured. Finally, the microstructures realized with the various mixtures have been found and correlated to the mechanical measurements and microstructures found in actual mixed formulation BGA solder joints. The results for the mechanical and physical properties show a very complicated dependence on the mixture ratio.

Copyright © 2009 by ASME
Topics: Solder joints



Interactive Graphics


Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In