The microstructure of Sn in near-eutectic Sn–Ag–Cu alloy solder joints and its role in thermomechanical fatigue

Autor: Paul A. Lauro, Sung K. Kang, L.P. Lehman, Karl J. Puttlitz, T.M. Korhonen, David E. King, Charles C. Goldsmith, James John Woods, Da-Yuan Shih, Matt A. Korhonen, Jay Bartelo, Donald W. Henderson, Eric J. Cotts, Timothy A. Gosselin
Rok vydání: 2004
Předmět:
Zdroj: Journal of Materials Research. 19:1608-1612
ISSN: 2044-5326
0884-2914
DOI: 10.1557/jmr.2004.0222
Popis: During the solidification of solder joints composed of near-eutectic Sn–Ag–Cu alloys, the Sn phase grows rapidly with a dendritic growth morphology, characterized by copious branching. Notwithstanding the complicated Sn growth topology, the Sn phase demonstrates single crystallographic orientations over large regions. Typical solder ball grid array joints, 900 μm in diameter, are composed of 1 to perhaps 12 different Sn crystallographic domains (Sn grains). When such solder joints are submitted to cyclic thermomechanical strains, the solder joint fatigue process is characterized by the recrystallization of the Sn phase in the higher deformation regions with the production of a much smaller grain size. Grain boundary sliding and diffusion in these recrystallized regions then leads to extensive grain boundary damage and results in fatigue crack initiation and growth along the recrystallized Sn grain boundaries.
Databáze: OpenAIRE
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