Nucleation and Growth of Tin in Pb-Free Solder Joints
Nucleation and Growth of Tin in Pb-Free Solder Joints
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DOI：
10.1007/s11837-015-1582-6
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发表时间：
2015-08
期刊：
影响因子：
2.6
通讯作者：
C. Gourlay;S. Belyakov;Z. Ma;J. Xian
中科院分区：
文献类型：
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作者：
C. Gourlay;S. Belyakov;Z. Ma;J. Xian
概述了无铅焊点的凝固，重点是βSn晶粒结构和晶粒取向的形成。以电子制造中常用的三种焊料 Sn-3Ag-0.5Cu、Sn-3.5Ag 和 Sn-0.7Cu-0.05Ni 作为案例研究，以证明 (I) 在过冷熔体生长过程中初生枝晶和共晶前沿之间的生长竞争对于无铅焊料非常重要，以及 (II) Sn-3.5Ag/Ni 接头中含有 NiSn4 形式的亚稳态共晶。此外，研究表明基材（金属化）对锡的成核和生长有很大影响。我们认为 Co、Pd 和 Pt 基材具有控制凝固和微观结构形成的潜力。在 Pd 和 Pt 基材的情况下，βSn 在 ~4 K 的相对较低过冷度下在 PtSn4 或 PdSn4 金属间化合物 (IMC) 反应层上成核，即使对于小至 <200μm 的小焊球直径也是如此。
The solidification of Pb-free solder joints is overviewed with a focus on the formation of theβSn grain structure and grain orientations. Three solders commonly used in electronics manufacturing, Sn-3Ag-0.5Cu, Sn-3.5Ag, and Sn-0.7Cu-0.05Ni, are used as case studies to demonstrate that (I) growth competition between primary dendrites and eutectic fronts during growth in undercooled melts is important in Pb-free solders and (II) a metastable eutectic containing NiSn4forms in Sn-3.5Ag/Ni joints. Additionally, it is shown that the substrate (metallization) has a strong influence on the nucleation and growth of tin. We identify Co, Pd, and Pt substrates as having the potential to control solidification and microstructure formation. In the case of Pd and Pt substrates,βSn is shown to nucleate on the PtSn4or PdSn4intermetallic compound (IMC) reaction layer at relatively low undercooling of ~4 K, even for small solder ball diameters down to <200μm.