0

Full Content is available to subscribers

Subscribe/Learn More  >

Aging Effects on the Mechanical Behavior and Reliability of SAC Alloys

[+] Author Affiliations
Yifei Zhang, Zijie Cai, Jeffrey C. Suhling, Pradeep Lall

Auburn University, Auburn, AL

Paper No. InterPACK2009-89373, pp. 959-976; 18 pages
doi:10.1115/InterPACK2009-89373
From:
  • 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

abstract

The microstructure, mechanical response, and failure behavior of lead free solder joints in electronic assemblies are constantly evolving when exposed to isothermal aging and/or thermal cycling environments. In our prior work on aging effects, we have demonstrated that the observed material behavior variations of Sn-Ag-Cu (SAC) lead free solders during room temperature aging (25°C) and elevated temperature aging (125°C) were unexpectedly large and universally detrimental to reliability. Such effects for lead free solder materials are especially important for the harsh applications environments present in high performance computing and in automotive, aerospace, and defense applications. However, there has been little work in the literature, and the work that has been done has concentrated on the degradation of solder ball shear strength (e.g. Dage Shear Tester). Current finite element models for solder joint reliability during thermal cycling accelerated life testing are based on traditional solder constitutive and failure models that do not evolve with material aging. Thus, there will be significant errors in the calculations with the new lead free SAC alloys that illustrate dramatic aging phenomena. In the current work, we have extended our previous studies to include a full test matrix of aging temperatures and solder alloys. The effects of aging on mechanical behavior have been examined by performing stress-strain and creep tests on four different SAC alloys (SAC105, SAC205, SAC305, SAC405) that were aged for various durations (0–6 months) at room temperature (25°C), and several elevated temperatures (50, 75, 100, and 125°C). Analogous tests were performed with 63Sn-37Pb eutectic solder samples for comparison purposes. Variations of the mechanical and creep properties (elastic modulus, yield stress, ultimate strength, creep compliance, etc.) were observed and modeled as a function of aging time and aging temperature. In this paper, we report on the creep results. The chosen selection of SAC alloys has allowed us to explore the effects of silver content on aging behavior (we have examined SACN05 with N = 1%, 2%, 3%, and 4% silver; with all alloys containing 0.5% copper). In order to reduce the aging induced degradation of the material behavior of the SAC alloys, we are testing several doped SAC alloys in our ongoing work. These materials include SAC0307-X, SAC105-X, and SAC305-X; where the standard SAC alloys have been modified by the addition of small percentages of one or more additional elements (X). Using dopants (e.g. Bi, In, Ni, La, Mg, Mn, Ce, Co, Ti, etc.) has become widespread to enhance shock/drop reliability, and we have extended this approach to examine the ability of dopants to reduce the effects of aging and extend thermal cycling reliability.

Copyright © 2009 by ASME

Figures

Tables

Interactive Graphics

Video

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

NOTE:
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.

Related eBook Content
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