Nucleation of tin on the Cu₆Sn₅ layer in electronic interconnections

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• 作者：J.W. Xian ; ^{j.xian@imperial.ac.uk" class="auth_mail" title="E-mail the corresponding author} ; Z.L. Ma ; S.A. Belyakov ; M. Ollivier ; C.M. Gourlay
• 关键词：Heterogeneous nucleation of phase ; 3D characterization ; EBSD ; Soldering
• 刊名：Acta Materialia
• 出版年：2017
• 出版时间：15 January 2017
• 年：2017
• 卷：123
• 期：Complete
• 页码：404-415
• 全文大小：4351 K

文摘

A Cu₆Sn₅ layer is an integral part of many electronic interconnections. Here we show that, although primary Cu₆Sn₅ is not a potent nucleant for Sn, the Cu₆Sn₅ layer plays a key role in Sn nucleation and microstructure formation in solder joints. Combining thermal analysis, FIB-tomography and EBSD, we show that conical cavities are present between the scallops of the Cu₆Sn₅ layer that act as geometric nucleation sites for Sn, that Sn grows from the Cu₆Sn₅ layer, and that reproducible nucleation orientation relationships (ORs) exist between Cu₆Sn₅ and Sn. With these ORs, a near-random distribution of Sn orientations is predicted from joint to joint even for Cu₆Sn₅ layers with a strong [0001] fibre texture. It is shown that the nucleation undercooling is strongly affected by manipulation of the Cu₆Sn₅ layer shape, and that it is possible to prevent nucleation on the Cu₆Sn₅ layer by adding more potent nucleants.