Thermal stress driven Sn whisker growth: in air and in vacuum
Thermal stress driven Sn whisker growth: in air and in vacuum
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热应力驱动锡晶须生长：在空气和真空中
DOI：
10.1007/s10854-013-1336-6
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Katsuaki Suganuma
中科院分区：
文献类型：
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作者：
Jung-Lae Jo;Shijo Nagao;Tohru Sugahara;Masanobu Tsujimoto;Katsuaki Suganuma
在空气或真空中，在热循环高达1，000次的过程中，观察到了来自哑光锡电镀的晶须生长。在本研究中，热应力晶须的密度、长度和宽度取决于2 μ m和5 μm的镀层厚度。2 μm镀层上生长的胡须比5 μm镀层上生长的胡须更长、更细。在这两种情况下，晶须在真空中比在空气中生长得更薄更快。这些明显的变化来自于电镀过程中的晶粒尺寸和热应力分布，在2 μ m和5 μm厚的薄膜中存在本质上的不同。晶须根部的晶粒结构，特别是在空气中氧化的晶界裂纹，决定了驱动晶须生长的应力集中。在真空中很少观察到氧化引起的裂纹，因此即使厚镀层也会产生细而直的晶须。我们的研究结果表明，在晶须根部晶粒的应力集中是必不可少的晶须生长形态控制，并有各种电子应用的关键影响。
Whisker growths from matte tin electroplating have been observed during thermal cycling up to 1,000 cycles either in air or in vacuum. The density, length, and width of thermal stress whiskers depend on the plating thickness of 2 and 5 μm in the present study. Whiskers grown on the 2 μm plating are longer and thinner than those on 5 μm plating. In both cases, whiskers grow thinner and faster in vacuum than in air. These apparent variations come from the grain sizes and the thermal stress distributions in the electroplating, intrinsically different in 2 and 5 μm thick films. The grain structure of whisker root, particularly grain boundary cracks oxidized in air, determines the stress concentration to drive the whisker growth. Cracking caused by oxidation was rarely observed in vacuum hence causes thin and straight whiskers even from thick plating. Our results indicate that the stress concentration at whisker root grain is essential for controlling whisker growth morphology, and has a critical impact on various electronic applications.