Study on Suppression of External Stress Type Tin Whisker by PR Current Method

Iwamoto, Hiroyuki; Nakamura, Katsuji; Tsuruta, Kaichi; Munekata, Osamu

doi:10.23919/icep51988.2021.9451952

Cited by 1 publication

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“…Several theories are proposed to explain the daunting whisker nucleation and growth for several metallic systems [ 1 , 2 , 3 ], with a majority following the explanation of stress-induced growth [ 3 , 17 , 18 ]. The stress-induced theory is supported by many researchers that have proven that stress originating from material deposition [ 19 , 20 ], the formation of intermetallic phases [ 21 , 22 , 23 ], oxidation [ 24 , 25 , 26 ] or externally applied stress [ 27 , 28 , 29 , 30 ] causes whisker growth. However, whisker formation is not homogeneous nor simultaneous.…”

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confidence: 99%

Revealing the Pb Whisker Growth Mechanism from Al-Alloy Surface and Morphological Dependency on Material Stress and Growth Environment

et al. 2022

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Spontaneous metallic Pb whisker formation from Pb and Bi containing Al-alloy’s surfaces is a newly discovered phenomenon. The whiskers display unique formations, growth and morphology, which give the opportunity to be applied for specialized sensor and electronics applications. Within this work, the impact of environmental conditions (gas composition and moisture) is investigated and correlated with the modification of whisker evolution and growth dynamics. Furthermore, the residual stress state of the aluminum matrix using deep cryogenic treatment is modified and used to further increase whisker nucleation and growth by up to three- and seven-fold, respectively, supported by quantitative results. The results of this paper indicate the possibility to manipulate the whisker not only in terms of their kinetics but also their morphology (optimal conditions are 20% O2 and 35% humidity). Such features allow the tailoring of the whisker structure and surface to volume ratio, which can be optimized for different applications. Finally, this research provides new insight into the growth dynamics of the whiskers through in situ and ex situ measurements, providing further evidence of the complex nucleation and growth mechanisms that dictate the spontaneous growth of Pb whiskers from Al-alloy 6026 surfaces with growth velocities up to 1.15 µm/s.

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