Title: Microstructure evolution based acceleration factor determination for SnAgCu solder joints during thermal cycling

Authors: Krishna Tunga, Suresh K. Sitaraman

Addresses: The George W. Woodruff School of Mechanical Engineering 360 CASPaR Laboratory, MaRC Building, 813 Ferst Drive Georgia Institute of Technology Atlanta, GA 30332-0405, USA. ' The George W. Woodruff School of Mechanical Engineering 360 CASPaR Laboratory, MaRC Building, 813 Ferst Drive Georgia Institute of Technology Atlanta, GA 30332-0405, USA

Abstract: The reliability of lead-free solder used in electronic packages during field-use conditions has traditionally been determined using accelerated thermal cycling (ATC) combined with a Norris-Landzberg type acceleration factor. Limited amount of work exists in quantifying the microstructure evolution of lead-free solder during thermal cycling especially during long-term thermal excursions. A phase coarsening based microstructure evolution has been used in the present work to determine the acceleration factor during thermal cycling. Two different plastic ball grid array (PBGA) packages with different sizes and two different lead-free solder alloys, Sn4.0Ag0.5Cu and Sn3.0Ag0.5Cu, were chosen for the study. The acceleration factor can be determined and hence the package can be qualified for field-use conditions in about the same time duration it takes to perform the ATC test.

Keywords: microstructure evolution; lead free soldering; solder joint fatigue; acceleration factor; phase growth; electronic packaging; thermo-mechanical stress; plastic ball grid array; PBGA; accelerated thermal cycling; ATC; SAC305; SAC405; solder joints; solder joint reliability.

DOI: 10.1504/IJMSI.2008.018906

International Journal of Materials and Structural Integrity, 2008 Vol.2 No.1/2, pp.173 - 192

Available online: 21 Jun 2008 *

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