The effect of electroplating parameters and substrate material on tin whisker formation

Ashworth, Mark; Wilcox, G.D.; Higginson, R.L.; Heath, Richard J.; Liu, Chanqing; Mortimer, Roger J.

doi:10.1016/j.microrel.2014.10.005

Cited by 49 publications

(30 citation statements)

References 37 publications

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“…While the current density affected surface morphology and the solution pH affected the crystal orientation of tin deposits, the current density and pH had no significant effect on the grain size. 55 Other investigations include the control of electroplating parameters to engender tin electrodeposit with a microstructure and grain orientation that were inherently resistant to whisker growth 56 . It is generally postulated that deposits with columnar grain structures are more susceptible to whisker growth than those with equiaxed grain structures 57 .…”

Section: Operating Parameters and Deposit Propertiesmentioning

confidence: 99%

A review of developments in the electrodeposition of tin

Walsh

Low

2016

Surface and Coatings Technology

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Highlights Types of aqueous electrolytes for pure tin deposits are reviewed. The many existing and developing applications of tin deposits are summarised. Emphasis is placed on versatile methanesulfonic acid electrolytes. The effects of bath composition (including additives) and operating conditions on deposit morphology are illustrated. Electrochemical studies at static and controlled flow rotating electrodes are illustrated. AbstractThe importance of tin and its electrodeposition are summarised and the scope for plating tin is outlined.Established applications of electroplated tin include corrosion protection, electronics fabrication and cooking utensils. The past 20 years have seen developments in the science and technology of tin plating, including research into nanostructured deposits, adoption of environmentally friendly methanesulfonic acid baths and more ambitious coatings including multi-layers and composites. Our ability to tailor deposit structure and composition has been improved by newer electrolytes, pulse plating and electrolyte additives. The diversity of tin applications has extended to lithium batteries using newer structures (such as composites, multi-layers and nanostructures), electrical control (e.g., pulsed current) and relative bath/electrode movement (including the use of rotating electrodes). Electrochemical aspects of modern tin deposition are illustrated by data from the authors' laboratory which highlights the versatility of methanesulfonic acid electrolytes. A wide range of deposit morphology, colour and surface finish are possible by the use of suitable addition agents and control of electrode/electrolyte movement and operating conditions. Subject areas needing further research work are identified.

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Section: Operating Parameters and Deposit Propertiesmentioning

confidence: 99%

A review of developments in the electrodeposition of tin

Walsh

Low

2016

Surface and Coatings Technology

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“…An important observation is that there is a large difference in the whisker densities for the native oxides, ranging from ~1200 cm -2 to ~3700 cm -2 . There are a number of possible explanations for this difference: firstly whisker growth is, by nature, unpredictable and sample to sample variations in whisker density are not uncommon 22 . Secondly, there may be slight variations in the Cu content of the deposit, due to either Sn or Cu depletion since an inert counter electrode is being used and the electroplating bath is not being replenished with fresh metal ions.…”

Section: Sn-cu Electrodeposits On Cumentioning

confidence: 99%

Tin whisker mitigation by means of a post-electroplating electrochemical oxidation treatment

Haspel

Ashworth

et al. 2015

Transactions of the IMF

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There are very few studies that have investigated directly the effect of an oxide film on tin whisker growth, since the 'cracked oxide theory' was proposed by Tu in 19941 . The current study has investigated the effect of an electrochemically produced oxide on tin whisker growth, for both Sn-Cu electrodeposits on Cu and pure Sn electrodeposits on brass. X-ray photoelectron spectroscopy (XPS) has been used to investigate the effect of the applied electrochemical oxidation potential on the oxide film thickness. Focused ion beam (FIB) has been used to prepare cross sections from electrodeposited samples to investigate the influence of the electrochemically formed oxide film on deposit microstructure during longterm room temperature storage. The XPS studies show that the thickness of electrochemically formed oxide film is directly influenced by the applied potential and the total charge passed. Whisker growth studies show that the electrochemical oxidation treatment mitigates whisker growth for both Sn-Cu electrodeposits on Cu and pure Sn electrodeposits on brass. For Sn electrodeposits on brass, the electrochemically formed oxide greatly reduces both the formation of zinc oxide at the surface and the formation of intermetallic compounds, which results in the mitigation of tin whisker growth. For Sn-Cu electrodeposits on Cu, the electrochemically formed oxide has no apparent effect on intermetallic compound formation and acts simply as a physical barrier to hinder tin whisker growth.

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“…Sn whiskers present a reliability risk for microelectronic devices because they can form short circuits between the terminals of the components. Sn whisker growth is induced by compressive stress on the Sn layer such as direct external mechanical load (by mechanically closing connectors or test needles), residual stress by the Sn layer deposition [3], volumetric expansion by oxide and intermetallic development [4,5], and thermomechanical effects [6]. The whisker development is a type of stress release mechanism for the tin layer against compressive stresses.…”

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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 effect of electroplating parameters and substrate material on tin whisker formation

Cited by 49 publications

References 37 publications

A review of developments in the electrodeposition of tin

A review of developments in the electrodeposition of tin

Tin whisker mitigation by means of a post-electroplating electrochemical oxidation treatment

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

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