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

2020 ◽  
Vol 31 (19) ◽  
pp. 16314-16323 ◽  
Author(s):  
Balázs Illés ◽  
Olivér Krammer ◽  
Tamás Hurtony ◽  
Karel Dušek ◽  
David Bušek ◽  
...  
Keyword(s):  
Thin Films ◽  
Growth Rates ◽  
Whisker Growth ◽  
Layer Structure ◽  
Intermetallic Layer ◽  
Layer Growth ◽  
Sn Whisker ◽  
Cu Substrate ◽  
Sn Whiskers ◽  
Kinetics Of

Abstract 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.

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

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3609 ◽  
Author(s):  
Balázs Illés ◽  
Tamás Hurtony ◽  
Olivér Krammer ◽  
Bálint Medgyes ◽  
Karel Dušek ◽  
...  
Keyword(s):  
Thin Films ◽  
Layer Thickness ◽  
Layer Structure ◽  
Intermetallic Layer ◽  
Copper Substrate ◽  
Substrate Roughness ◽  
Cu Substrate ◽  
Layer Deposition ◽  
Cu Substrates ◽  
Effect Of Copper

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.

Kinetics of intermetallic compound layers and Cu dissolution at Sn1.5Cu/Cu interface under high magnetic field

2010 ◽  
Vol 25 (2) ◽  
pp. 359-367 ◽  
Author(s):  
Cong-qian Cheng ◽  
Jie Zhao ◽  
Yang Xu
Keyword(s):  
Magnetic Field ◽  
Intermetallic Compound ◽  
Lorentz Force ◽  
High Magnetic Field ◽  
Solubility Limit ◽  
Layer Growth ◽  
Ripening Process ◽  
Cu Substrate ◽  
Cu Dissolution ◽  
Kinetics Of

The kinetics of intermetallic compound (IMC) layer and Cu dissolution at Sn1.5Cu/Cu interface under high magnetic field was experimentally examined. It is found that the IMC layer growth is controlled by flux-driven ripening process. The high magnetic field promotes the growth of IMC layer, retards the dissolution of Cu substrate, and decreases the content of Cu solute at the liquid–IMC interface front. Based on the experimental results, it is considered that the magnetization induced by magnetic field promotes the ripening process for IMC layer growth. The Lorentz force dampening the convection and magnetization decreasing the Cu solubility limit can retard the Cu dissolution and change the solute distribution at the liquid–IMC interface front.

Effect of Environment on Sn Whisker Growth during Welding of Electronic Wires

2015 ◽  
Vol 1110 ◽  
pp. 235-240 ◽  
Author(s):  
Tomomi Sakakida ◽  
Tatsuo Kubouchi ◽  
Yasuyuki Miyano ◽  
Mamoru Takahashi ◽  
Osamu Kamiya
Keyword(s):  
Energy Balance ◽  
Weld Metal ◽  
Whisker Growth ◽  
Weld Zone ◽  
Electrolytic Capacitor ◽  
Sn Whisker ◽  
Sn Whiskers ◽  
Weld Metal Microstructure ◽  
Short Circuits ◽  
Metal Microstructure

In Pb-free Al-Sn welding of electrolytic parts, single-crystal Sn whiskers easily form and can cause problems such as short circuits. Here we report that the growth of Sn whiskers in the weld zone of Al electrolytic condenser leads was suppressed in a vacuum environment. We examined the effect of the environment and weld metal microstructure in order to understand how to control and prevent whisker growth. In vacuum, the weld zone did not form whiskers after more than 100 h, whereas in air, whiskers grew within several hours. This suggests that whiskers require oxygen to form. The growth can be explained by the energy balance between the potential energy of the weld metal and the surface energy of the whisker. Our results will contribute to developing techniques for suppressing the formation of Sn whiskers during the percussion welding of Al electrolytic capacitor leads.

Chemical Bath Deposition of CdS Thin Films: Growth and Structural Studies

1996 ◽  
Vol 426 ◽  
Author(s):  
Yuming Zhu ◽  
Dull Mao ◽  
D. L. Williamson ◽  
J. U. Trefny
Keyword(s):  
Thin Films ◽  
Structural Properties ◽  
Deposition Time ◽  
Layer Structure ◽  
Layer Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thiourea Solution ◽  
Cds Thin Films ◽  
Cds Films

AbstractChemical-bath-deposited CdS thin films from an ammonia-thiourea solution have been studied by x-ray diffraction, surface profilometry, ellipsometry, and other techniques. The compactness of the CdS films, structural properties of the films, and the growth mechanism have been investigated. For the deposition conditions used, we found that the film compactness reaches its maximum at a deposition time of 35 minutes. Films grown at longer deposition times are less compact, consistent with the CdS duplex layer structure proposed previously. This transition from compact layer growth to porous layer growth is important for depositing CdS films in solar cell applications. Based on x-ray diffraction (XRD) studies, we were able to determine the crystal phase, lattice constant, and other structural properties.

Spontaneous Tin (Sn) Whisker Growth from Electroplated Tin and Lead-Free Tin Alloys Coatings: A Short Review

2018 ◽  
Vol 280 ◽  
pp. 151-156 ◽  
Author(s):  
Aimi Noorliyana Hashim ◽  
Mohd Arif Anuar Mohd Salleh
Keyword(s):  
Driving Force ◽  
Room Temperature ◽  
Whisker Growth ◽  
Copper Substrate ◽  
Short Review ◽  
Hazardous Substances ◽  
Lead Free ◽  
Sn Whisker ◽  
Tin Alloys ◽  
Sn Whiskers

Since the environmental regulations of Reduction of Hazardous Substances (RoHS) directive came into effect in Europe and Asia on July 1, 2006, requiring the removal of any lead (Pb) content from the electronics industry, the issue of tin (Sn) whisker growth from pure Sn and SnPb-free alloys has become one of the most imperative issues that need to be resolved. Moreover, with the increasing demand for electronics miniaturization, Sn whisker growth is a severe threat to the reliability of microelectronic devices. Sn whiskers grow spontaneously from an electrodeposited tin coating on a copper substrate at room temperature, which can lead to well-documented system failures in electronics industries. The Sn whisker phenomenon unavoidably gives rise to troubles. This paper briefly reviews to better understand the fundamental properties of Sn whisker growth and at the same time discover the effective mitigation practices for whisker growth in green electronic devices. It is generally accepted that compressive stress generated from the growth of Cu6Sn5 intermetallic compound (IMC) is the primary driving force for Sn whisker growth during room temperature storage. It is, therefore, important to determine that the relationship between IMC growth and Sn whisker growth. Reduction of stress in the IMC layer can therefore reduce the driving force for whisker formation and be used as a means for whisker mitigation. To date, there are no successful methods that can suppress the growth of Sn whisker as efficient as Pb addition. It is hoped that the Sn whisker growth mechanisms are understood better in the future, with better measuring and monitoring methodologies and systems being developed, the real solutions may be eventually developed to eliminate or mitigate the Sn whisker problems of green reliability lead-free electronic assemblies.

Effect of Sn Film Grain Size and Thickness on Kinetics of Spontaneous Sn Whisker Growth

JOM ◽  
2019 ◽  
Vol 71 (9) ◽  
pp. 3041-3048 ◽  
Author(s):  
Wen-Chih Lin ◽  
Tsan-Hsien Tseng ◽  
Wei Liu ◽  
Kuo-Shuo Huang ◽  
Hao Chen ◽  
...  
Keyword(s):  
Grain Size ◽  
Whisker Growth ◽  
Sn Whisker ◽  
Kinetics Of

scholarly journals Electromigration-induced Pb and Sn whisker growth in SnPb solder stripes

2008 ◽  
Vol 23 (7) ◽  
pp. 2017-2022 ◽  
Author(s):  
C.C. Wei ◽  
P.C. Liu ◽  
Chih Chen ◽  
K.N. Tu
Keyword(s):  
Compressive Stress ◽  
Whisker Growth ◽  
Accelerated Tests ◽  
Sn Whisker ◽  
Growth Orientation ◽  
Sn Whiskers ◽  
Snpb Solder

Electromigration at 5 × 104 A/cm2 and 100 °C was conducted to grow composite Pb/Sn whiskers from SnPb solders, in which a Pb whisker grows first and then a whisker of Sn grows. In some cases, small Sn islands are embedded in Pb whiskers. The diameter of a composite whisker is <1 μm, which is much smaller than that of spontaneous Sn whisker growth on leadframes. The growth orientation of Pb whiskers was in the [110], [1¯11], and [112] directions. This investigation proposes that compressive stress generated by electromigration at the anode provides the force driving whisker growth. Therefore, accelerated tests of whisker growth at higher temperatures using electromigration are feasible.

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

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 738
Author(s):  
Aimi Noorliyana Hashim ◽  
Mohd Arif Anuar Mohd Salleh ◽  
Andrei Victor Sandu ◽  
Muhammad Mahyiddin Ramli ◽  
Khor Chu Yee ◽  
...  
Keyword(s):  
Solder Joint ◽  
Interfacial Layer ◽  
Whisker Growth ◽  
Intermetallic Layer ◽  
Nucleation And Growth ◽  
Noticeable Effect ◽  
Sn Whisker ◽  
Electron Imaging Mode ◽  
Free Solder ◽  
Electron Imaging

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.

Growth Kinetics of Intermetallic Compounds at the Interface of Liquid Sn-9Zn/Cu

2011 ◽  
Vol 233-235 ◽  
pp. 2323-2327
Author(s):  
Hui Zhen Huang ◽  
Xiu Qin Wei ◽  
Lang Zhou
Keyword(s):  
Activation Energy ◽  
Intermetallic Compound ◽  
Intermetallic Compounds ◽  
Solder Alloy ◽  
Growth Kinetics ◽  
Layer Growth ◽  
Experimental Results ◽  
Cu Substrate ◽  
Diffusion Mechanisms ◽  
Kinetics Of

The morphology and growth of the intermetallic compound (IMC) formed between liquid Sn-9Zn eutectic solder alloy and Cu at 220-260°C was investigated. Experimental results showed that γ-Cu5Zn8 was present at the Sn-9Zn/Cu interface as the reaction product. The IMC layer growth follows the parabolic-growth law, which indicates that the growth of the IMC is controlled by the diffusion mechanisms. The activation energy of γ-Cu5Zn8 layer growth for liquid Sn-9Zn reacting with Cu substrate is determined as 50.5 KJ/mol.

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