TY - JOUR
T1 - Microstructure characterization and creep behavior of Pb-free Sn-rich solder alloys
T2 - Part I. Microstructure characterization of bulk solder and solder/copper joints
AU - Sidhu, R. S.
AU - Chawla, Nikhilesh
N1 - Funding Information:
The authors acknowledge financial support for this research from the National Science Foundation under Contract No. DMR-0092530 (Drs. H. Chopra, S. An-kem, B. Macdonald, and K.L. Murty, program managers). The authors also thank Indium Corporation for supplying the solders used in this study.
PY - 2008/2
Y1 - 2008/2
N2 - Solders are used as interconnect materials in microelectronic packaging. Traditionally, eutectic and near-eutectic Pb-Sn solder alloys have been used. Due to the toxic nature of lead, environmentally-benign Sn-rich (Pb-free) solders are being developed. In this two part series of articles, we have focused on elucidating the relationship between microstructure and creep behavior of Sn-rich alloys, both in bulk form and at the solder sphere joint level. Part I of our study focuses on a detailed quantitative analysis of the effect of controlled cooling rates on solder microstructures. Bulk solder microstructures from cast bars were compared to smaller solder joint microstructures, reflowed from single solder spheres about 1 mm in diameter. Faster cooling rates resulted in much finer secondary dendrite size and spacing, as well as a much finer distribution of Ag3Sn and Cu6 Sn5 particles. The companion article, Part II, provides a unified mechanistic understanding of the creep behavior for the Sn-rich solder alloys, intimately linked to the microstructure characterization work reported in Part I.
AB - Solders are used as interconnect materials in microelectronic packaging. Traditionally, eutectic and near-eutectic Pb-Sn solder alloys have been used. Due to the toxic nature of lead, environmentally-benign Sn-rich (Pb-free) solders are being developed. In this two part series of articles, we have focused on elucidating the relationship between microstructure and creep behavior of Sn-rich alloys, both in bulk form and at the solder sphere joint level. Part I of our study focuses on a detailed quantitative analysis of the effect of controlled cooling rates on solder microstructures. Bulk solder microstructures from cast bars were compared to smaller solder joint microstructures, reflowed from single solder spheres about 1 mm in diameter. Faster cooling rates resulted in much finer secondary dendrite size and spacing, as well as a much finer distribution of Ag3Sn and Cu6 Sn5 particles. The companion article, Part II, provides a unified mechanistic understanding of the creep behavior for the Sn-rich solder alloys, intimately linked to the microstructure characterization work reported in Part I.
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U2 - 10.1007/s11661-007-9414-0
DO - 10.1007/s11661-007-9414-0
M3 - Article
AN - SCOPUS:38649088577
SN - 1073-5623
VL - 39
SP - 340
EP - 348
JO - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
JF - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
IS - 2
ER -