Roll of Grain-boundary Free Energy & Surface Free Energy for Tin Whisker Growth
Roll of Grain-boundary Free Energy & Surface Free Energy for Tin Whisker Growth
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晶界自由能卷
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
U. Lindborg
中科院分区：
文献类型：
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作者：
K. Tsuji;J. D. Eshelby;U. Lindborg
一般来说，电镀锡层的晶粒尺寸相当小。因此，晶界自由能有望成为再结晶和随后锡晶须生长的驱动力。另一方面，如果结构的尺寸足够小，如晶须，那么结构的形态将主要由降低其表面自由能的趋势决定。因此，表面自由能可能与晶须生长过程密切相关。本文通过测定锡镀层的晶粒尺寸与厚度的关系，估计了锡镀层的晶界自由能。然后，研究了各种晶须和所谓的结核的形态，即从锡表面不规则形状的大量挤压，以揭示表面自由能在晶须生长过程中的滚动。同时，利用电子背散射衍射图方法研究了晶粒生长与晶粒生长的关系，晶粒生长是再结晶的一个阶段。结果表明，晶界自由能足以使晶粒生长自发发生，晶粒生长导致结核生长。而许多须被发现生长在结节上。这意味着晶须的生长与结核的生长密切相关。由此可见，晶须生长可以理解为结核表面自由能最小化的结果，结核由于其复杂的表面而具有较大的表面自由能。此外，有人建议通过在<001>、<100>、<101>和<111>等特定方向生长来实现最小化。
Generally the grains of electroplated tin layers are considerably small in their sizes. Therefore the grain-boundary free energy is expected to act as a driving force for recrystallization and possibly subsequent tin whisker growth. On the other hand, if the dimension of a structure is sufficiently small like whiskers, then the morphology of the structure will be determined principally by the tendency to lower its surface free energy. Hence it is supposed that the surface free energy may be closely related to the whisker growth process. In this work, the grain-boundary free energy of tin electrodeposits has been estimated by determining the grain sizes as a function of the thickness. Then the morphology of various whiskers and so-called nodules, which are the irregularly shaped mass-extrusion from the tin surface, has been studied in order to reveal the roll of surface free energy in the whisker growth process. While the relation between the nodule growth and the grain growth, which is a stage of recrystallization, has been also studied by electron backscatter diffraction pattern method. It has been shown that the grain-boundary free energy is sufficient for spontaneous occurrence of grain growth of the deposits and the grain growth lead to the nodule growth. While many whiskers were found to grow on nodules. This means the whisker growth is closely related to the nodule growth. From these, it has been suggested that the whisker growth can be understood as a result of minimization of the surface free energy of nodules, which have large surface free energy as a result of their complicated surfaces. Farther more, it has been suggested that the minimization can be achieved by growing in some specific directions such as <001>, <100>, <101>, and <111>.