The influence of the crystallographic structure of the intermetallic grains on tin whisker growth

Illés, Béla; Skwarek, Agata; Ratajczak, J.; Dusek, Karel; Busek, David

doi:10.1016/j.jallcom.2019.01.247

Cited by 18 publications

(9 citation statements)

References 39 publications

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“…The layer thickness affects the grain size, which is 0.5–1 μm and 1–2 μm in the case of the 1 µm and 2 μm thick Sn layers respectively. The grain orientation of the Sn thin-film was determined by Selected Area Electron Diffraction (SAED) technique, and it was found to be generally <111>, Figure 1c [27].…”

Section: Methodsmentioning

confidence: 99%

Effect of Cu Substrate Roughness and Sn Layer Thickness on Whisker Development from Sn Thin-Films

et al. 2019

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The effect of copper substrate roughness and tin layer thickness were investigated on whisker development in the case of Sn thin-films. Sn was vacuum-evaporated onto both unpolished and mechanically polished Cu substrates with 1 µm and 2 μm average layer thicknesses. The samples were stored in room conditions for 60 days. The considerable stress—developed by the rapid intermetallic layer formation—resulted in intensive whisker formation, even in some days after the layer deposition. The developed whiskers and the layer structure underneath them were investigated with both scanning electron microscopy and ion microscopy. The Sn thin-film deposited onto unpolished Cu substrate produced less but longer whiskers than that deposited onto polished Cu substrate. This phenomenon might be explained by the dependence of IML formation on the surface roughness of substrates. The formation of IML wedges is more likely on rougher Cu substrates than on polished ones. Furthermore, it was found that with the decrease of layer thickness, the development of nodule type whiskers increases due to the easier diffusion of other atoms into the whisker bodies.

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Section: Methodsmentioning

confidence: 99%

Effect of Cu Substrate Roughness and Sn Layer Thickness on Whisker Development from Sn Thin-Films

et al. 2019

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“…Illes et al [ 21 ] surmise that the main source for whiskers growth is the non-uniform shape of IMC interfacial layers and expansion of the IMC interfacial layer at the solder/substrate interface layers [ 8 , 21 , 22 ]. As explained by Kim et al [ 22 ], the Sn whisker prone to grow with irregularly shaped due to high residual compressive stresses concentrated at IMC interfacial layer.…”

Section: Introductionmentioning

confidence: 99%

Effect of Ni on the Suppression of Sn Whisker Formation in Sn-0.7Cu Solder Joint

et al. 2021

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The evolution of internal compressive stress from the intermetallic compound (IMC) Cu6Sn5 growth is commonly acknowledged as the key inducement initiating the nucleation and growth of tin (Sn) whisker. This study investigates the effect of Sn-0.7Cu-0.05Ni on the nucleation and growth of Sn whisker under continuous mechanical stress induced. The Sn-0.7Cu-0.05Ni solder joint has a noticeable effect of suppression by diminishing the susceptibility of nucleation and growth of Sn whisker. By using a synchrotron micro X-ray fluorescence (µ-XRF) spectroscopy, it was found that a small amount of Ni alters the microstructure of Cu6Sn5 to form a (Cu,Ni)6Sn5 intermetallic layer. The morphology structure of the (Cu,Ni)6Sn5 interfacial intermetallic layer and Sn whisker growth were investigated by scanning electron microscope (SEM) in secondary and backscattered electron imaging mode, which showed that there is a strong correlation between the formation of Sn whisker and the composition of solder alloy. The thickness of the (Cu,Ni)6Sn5 IMC interfacial layer was relatively thinner and more refined, with a continuous fine scallop-shaped IMC interfacial layer, and consequently enhanced a greater incubation period for the nucleation and growth of the Sn whisker. These verification outcomes proposes a scientifically foundation to mitigate Sn whisker growth in lead-free solder joint.

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“…The Cu-Sn system has two possible IMC phases; they are the Cu 3 Sn and the Cu 6 Sn 5 . The Cu 3 Sn develops directly at the Cu-Sn interface, and usually in a small amount compared to the Cu 6 Sn 5 , which grows on the Cu 3 Sn towards Sn film-layer [31]. The volume ratio of the developed Cu 6 Sn 5 IMC is usually around 85-95% since the required energy for Cu 3 Sn formation is much higher than that for Cu 6 Sn 5 formation.…”

Section: Discussionmentioning

confidence: 99%

Kinetics of Sn whisker growth from Sn thin-films on Cu substrate

Illés

Krammer

Hurtony

et al. 2020

J Mater Sci: Mater Electron

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The kinetics of Sn whisker growth was investigated on vacuum-evaporated Sn thin-films. Sn film layers were deposited on a Cu substrate with 0.5 and 1 µm thicknesses. The samples were stored in room conditions (22 ± 1 °C/50 ± 5RH%) for 60 days. The Sn whiskers and the Cu–Sn layer structure underneath them were investigated with both scanning electron and ion microscopy. Fast Cu–Sn intermetallic formation resulted in considerable mechanical stress in the Sn layer, which initiated intensive whisker growth right after the layer deposition. The thinner Sn layer produced twice many whiskers compared to the thicker one. The lengths of the filament-type whiskers were similar, but the growth characteristics differed. The thinner Sn layer performed the highest whisker growth rates during the first 7 days, while the thicker Sn layer increased the growth rate only after 7 days. This phenomenon was explained by the cross-correlation of the stress relaxation ability of Sn layers and the amount of Sn atoms for whisker growth. The very high filament whisker growth rates might be caused by the interface flow mechanism, which could be initiated by the intermetallic layer growth itself. Furthermore, a correlation was found between the type of the whiskers and the morphology of the intermetallic layer underneath.

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The influence of the crystallographic structure of the intermetallic grains on tin whisker growth

Cited by 18 publications

References 39 publications

Effect of Cu Substrate Roughness and Sn Layer Thickness on Whisker Development from Sn Thin-Films

Effect of Cu Substrate Roughness and Sn Layer Thickness on Whisker Development from Sn Thin-Films

Effect of Ni on the Suppression of Sn Whisker Formation in Sn-0.7Cu Solder Joint

Kinetics of Sn whisker growth from Sn thin-films on Cu substrate

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