The dominant effect of c-axis orientation in tin on the electromigration behaviors in tricrystal Sn-3.0Ag-0.5Cu solder joints

Tian, Yu; Han, Jing; Ma, Limin; Guo, Fu

doi:10.1016/j.microrel.2017.11.005

Cited by 26 publications

(8 citation statements)

References 29 publications

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“…The main influencing properties of the layer are the size, shape, and crystallographic structure of the grains (mono- or polycrystalline and the orientation) [9,10], and the layer thickness [11]. In a fine grain structure (when the average grain size is smaller than 500 nm) the diffusivity is higher due to many grain boundaries [12], therefore the growth of the Intermetallic Layer (IML) is faster [13,14]. The more intensive growth of the IML layer causes more internal stress by volumetric expansion.…”

Section: Introductionmentioning

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: Introductionmentioning

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 influence of the grain size on whisker development is divided into two regimes. On one hand, small grains (<500nm) have more grain boundaries whereon electromigration causes higher diffusivity and results in fast intermetallic (IMC) layer growth [4,10]. Sun et.…”

mentioning

confidence: 99%

“…The crystallographic structure of the Sn layer itself also has an effect on the IMC layer formation, since Tian et. al showed that the direction of c-axis in Sn grains affect the growth of the IMC, and that the IMCs in the solder matrix grew in the direction of the electron flow towards the c-axis direction [10].…”

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confidence: 99%

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

Illés

Skwarek

Ratajczak

et al. 2019

Journal of Alloys and Compounds

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In this paper, the relationship between the crystallographic structure of Cu-Sn intermetallic grains and Sn whisker growth was investigated. In order to prevent the influence of the elements in the alloy composition and the effect of the soldering process on the formation of the intermetallic layer, 99.99% pure Sn was vacuum evaporated onto Cu substrates. The Sn layer thickness was sub-micron region (~400nm in average) to reach considerable and rapid compressive stress on the tin layer originated by the intermetallic formation. The samples were stored at room temperature for 1 month. Different types of whiskers (nodule and filament) and the layer structure underneath were studied with a scanning ion microscopy and transmission electron microscopy. It was found that not only the thickness of the intermetallic layer and shape of the intermetallic grains affects the whisker growth but the crystallographic structure of the intermetallic grains as well. The susceptibility of the Sn layer to whisker development is higher in those regions where the intermetallic layer is composed of monocrystalline grains instead of those regions, where it is composed of polycrystalline grains. This effect can be explained by the higher compressive stress generated by the monocrystalline intermetallics compared to the polycrystalline ones.

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“…The physical properties of the Sn grains,-size, shape, and crystallographic structure [8,9]-influence the propensity of whisker growth. A fine grain structure (grain size < 500 nm) enhances the grain boundary diffusion, so it results in fast intermetallic (IMC) layer growth [10,11]. Furthermore, Sun et al reported that under a long-term mechanical load, the increase in grain boundaries by the dislocations affects the whisker growth, since the new grain boundaries are the nucleation point of Sn whisker growth [12].…”

Section: Introductionmentioning

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 dominant effect of c-axis orientation in tin on the electromigration behaviors in tricrystal Sn-3.0Ag-0.5Cu solder joints

Cited by 26 publications

References 29 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

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

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

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