Investigation of relation between intermetallic and tin whisker growths under ambient condition

Kim, K.S.; Yu, Chung-Hee; Han, Sang-Wook; Yang, K.C.; Kim, J.H.

doi:10.1016/j.microrel.2007.01.088

Cited by 44 publications

(13 citation statements)

References 22 publications

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“…The most observed IMC compound was Cu6Sn5, which has lower density (8.27g/cm 3 ) than copper (8.96g/cm 3 ). This causes volume expansion at the IMC layer, which results in compressive stress on the Sn layer [20]. This compressive stress can be calculated [28]:…”

Section: Discussionmentioning

confidence: 99%

“…It was shown that not only the amount and thickness of the IMC layer is important, but also the shape of the IMC grains. A greater tendency for whiskers development was found on non-uniform (rough) IMC layers [19,20] and at larger IMC precipitates located between Sn grain boundaries [7]. From the point of the IMC layer development during the life cycle of the solder joints (in solid state), an important factor is the formation of the initial IMC layer during the soldering process (from the liquid state) [21] or during the layer deposition process [22].…”

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confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

mentioning

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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“…The intermetallic layer has lower density than copper and this density change causes the volume expansion at the intermetallic layer. The volume extension generates compressive stresses toward the tin film in the vertical direction of the Cu and Sn interface [25]. According to G. T. Galyon et al underlaying material such as nickel reverses these interdiffusional effects.…”

Section: Resultsmentioning

confidence: 99%

Effect of strongly oxidizing environment on whisker growth form tin coating

Illés

Horváth

Harsányi

2010

Surface and Coatings Technology

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“…This suggests that the Cu 6 Sn 5 functions as an effective diffusion barrier to the continued formation of intermetallic compound such that a significant proportion of the Cu barrier layer remains unreacted even after 32 years storage at room temperature. It is also interesting to note that the intermetallic layer is relatively planar and does not possess an overtly pronounced 'wedgeshaped' morphology that is often associated with an increased propensity for whisker growth (Baated et al 2011;Kim et al 2008). …”

Section: Discussionmentioning

confidence: 99%

An investigation of tin whisker growth over a 32-year period

Ashworth

Dunn

2016

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Purpose: This paper presents the results of a 32 year old laboratory study of whisker growth from tin electrodeposits that was originally undertaken to gain an increased understanding of the phenomenon of tin whisker growth.Design/methodology/approach: Whisker growth was evaluated using electroplated C-rings (both stressed and un-stressed) that were stored throughout in a desiccator at room temperature. Analysis has recently been undertaken to evaluate whisker growth and intermetallic growth after 32 years storage. SEM analysis has been performed to investigate whisker length and, using polished cross-sections, the morphology, thickness and type of intermetallic formation. Findings:Normal tin plated deposits on brass and steel with a copper barrier layer nucleated whiskers within 5 months and in each case these grew to lengths between 1 and 4.5 mm. For normal tin electroplated onto brass, a one or two month nucleation period was needed before whiskers developed. They reached a maximum length of about 1.5 mm after 6 months and little or no further growth occurred during the subsequent 32 years. Very few whiskers grew on the tin-plated steel samples and no intermetallic formation was observed.None of the fused tin-platings nucleated whiskers during the 32 year period. Practical implications:Knowledge about vintage whiskers is important in order that we can take steps to increase the resiliency of our space missions. Similarly, such knowledge is important to engineers engaged on products reaching their nominal end-of-life, but where for reasons of economy, these products cannot be replaced Originality/value: This study represents a unique insight into whisker growth and intermetallic formation over an extremely long time period.

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Investigation of relation between intermetallic and tin whisker growths under ambient condition

Cited by 44 publications

References 22 publications

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

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

Effect of strongly oxidizing environment on whisker growth form tin coating

An investigation of tin whisker growth over a 32-year period

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