Indentation-induced tin whiskers on electroplated tin coatings

Yang, Fuqian; Li, Yan

doi:10.1063/1.3033390

Cited by 22 publications

(8 citation statements)

References 15 publications

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“…The above described buckling yields a significant deflection λ < ∼ l. The results in Eqs. (12) and (13) coincide with that of exact analysis 21,22 to the accuracy of numerical coefficients of the order of unity.…”

Section: Uniform Whiskerssupporting

confidence: 68%

Understanding the movements of metal whiskers

Карпов

2015

Journal of Applied Physics

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Metal whiskers often grow across leads of electric equipment causing short circuits and raising significant reliability issues. Their nature remains a mystery after several decades of research. It was observed that metal whiskers exhibit large amplitude movements under gentle air flow or, according to some testimonies, without obvious stimuli. Understanding the physics behind that movements would give additional insights into the nature of metal whiskers. Here, we quantitatively analyze possible mechanisms of the observed movements: (1) minute air currents, (2) Brownian motion due to random bombardments with the air molecules, (3) mechanically caused movements, such as (a) transmitted external vibrations, and (b) torque exerted due to material propagation along curved whiskers (the garden hose instability), (4) time dependent electric fields due to diffusion of ions, and (5) non-equilibrium electric fields making it possible for some whiskers to move. For all these mechanisms we provide numerical estimates. Our conclusion is that the observed movements are likely due to the air currents or electric recharging caused by external light or similar factors.

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Section: Uniform Whiskerssupporting

confidence: 68%

Understanding the movements of metal whiskers

Карпов

2015

Journal of Applied Physics

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“…It was inferred also that the stress gradients can be more im-portant than stresses itself. [30][31][32][33] Unfortunately, these approaches lack predictive power providing no estimates for whisker growth rates and parameters.…”

Section: Introductionmentioning

confidence: 99%

Microscopic Structure of Metal Whiskers

et al. 2018

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We present TEM images of the interior of metal whiskers (MW) grown on electroplated Sn films. Along with earlier published information, our observations focus on a number of questions, such as why MWs' diameters are in the micron range (significantly exceeding the typical nano-sizes of nuclei in solids), why the diameters remain practically unchanged in the course of MW growth, what is the nature of MW diameter stochasticity, and what is the origin of the well-known striation structure of MW side surfaces. In an attempt to address such questions we performed an in-depth study of MW structure at the nanoscale by detaching a MW from its original film, reducing its size to a thin slice by cutting its sides by a focused ion beam, and performing TEM on that structure. Our observations revealed a rich nontrivial morphology suggesting that MW may consist of many side by side grown filaments. This structure appears to extend to the outside whisker surface and be the reason for the striation. In addition, we put forward a theory where nucleation of multiple thin metal needles results into micron-scale and larger MW diameters. This theory is developed in the average field approximation similar to the roughening transitions of metal surfaces. The theory also predicts MW nucleation barriers and other observed features.PACS numbers:

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“…Another important driving force for whisker growth is mechanically applied stress on the Sn sample. Numerous studies have investigated the application of mechanical stress using different loading devices, such as a clamping fixture, 21,36,58 three-point or four-point bending [59][60][61] of Sn-coated strips, micro-indentation, [62][63][64][65] and in situ nanoindentation. 66,67 Fisher et al, 21 using a ring clamp (shown in Fig.…”

Section: Externally Applied Mechanical Stressmentioning

confidence: 99%

Whisker Growth in Sn Coatings: A Review of Current Status and Future Prospects

Jagtap

Kumar

2020

Journal of Elec Materi

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Whiskering is a spontaneous filamentary growth of material, and it is a major long-term reliability issue affecting microelectronic packages comprising Sn plating and Sn-rich solders. In particular, whisker growth out of Sn-plated surfaces has been studied extensively in recent years due to the advent of next-generation, environment-friendly, Pb-free microelectronic packaging. Here, we review this scientifically challenging and technologically important problem, especially in the light of relatively new insights gained in the recent past, intending to provide a quick overview of the important results and stimulating future studies. In particular, we discuss the mechanisms of whisker growth by critically examining the roles of stress and its regeneration, oxide layer, diffusion conduits, and crystal anisotropy in creating conditions conducive for whiskering. We also discuss the recent proposals for effectively mitigating whisker growth in Sn coatings. Finally, an outlook is provided, with details of important unresolved issues related to whisker growth.

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Indentation-induced tin whiskers on electroplated tin coatings

Cited by 22 publications

References 15 publications

Understanding the movements of metal whiskers

Understanding the movements of metal whiskers

Microscopic Structure of Metal Whiskers

Whisker Growth in Sn Coatings: A Review of Current Status and Future Prospects

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