Spontaneous Growth Mechanism of Tin Whiskers

Published on Jan 1, 1998in Acta Metallurgica
B Z Lee1
Estimated H-index: 1
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#1Balázs Illés (BME: Budapest University of Technology and Economics)H-Index: 19
#2Tamás Hurtony (BME: Budapest University of Technology and Economics)H-Index: 7
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Abstract In the past years, the use of low silver content SAC0307 (99Sn0.3Ag0.7Cu wt%) solder alloy grew considerably due to its good soldering quality. In the latest version of this alloy, manganese, and bismuth are used to improve further its soldering parameters. In this study, a reliability issue, the whisker growth from SAC0307-Mn07 and SAC0307-Bi1-Mn07 solder alloys was investigated. Ultra-thin films (in 100–150 nm thickness) were vacuum evaporated from the investigated alloys onto Cu subs...
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#1Tadahiro Shibutani (Yokohama National University)H-Index: 14
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Abstract This paper discusses nucleation of stress-induced defects on a tin surface finish. The spring back effect was used to generate compressive stresses in the tin layer. In-situ observation was carried out by means of atomic force microscopy (AFM). Nucleation of defects was found in the observed area. AFM revealed that not only nucleation but also shrinkage of defects took place. Cross-section profiles revealed that defects are classified into hillocks. Since the tin crystal structure has a...
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#1M.J. Bozack (AU: Auburn University)H-Index: 1
#2S.K. Snipes (AU: Auburn University)H-Index: 1
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We report several methods to reliably grow dense fields of high-aspect ratio tin whiskers for research purposes in a period of days to weeks. The techniques offer marked improvements over previous means to grow whiskers, which have struggled against the highly variable incubation period of tin whiskers and slow growth rate. Control of the film stress is the key to fast-growing whiskers, owing to the fact that whisker incubation and growth are fundamentally a stress-relief phenomenon. The ability...
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#1Takahiko Kato (Yokohama National University)
#2Carol A. Handwerker (NIST: National Institute of Standards and Technology)H-Index: 29
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This chapter discusses the pressure‐induced whisker at separable interfaces as a key reliability issue of lead‐free separable contacts and connectors. It shows theories of mechanically induced tin whiskers. Then, several case studies with pure tin and lead‐free finishes were performed to evaluate pressure‐induced tin whiskers. For electronics components, several factors affect the stress field of the finish: (i) thickness of the plating, (ii) structure of the ambient component material, and (iii...
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#1Lutz Meinshausen (WSU: Washington State University)H-Index: 3
#2S. Bhassyvasantha (New Mexico Institute of Mining and Technology)H-Index: 2
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Among many factors that influence whisker nucleation and growth in electroplated tin, it is now well established that small additions of Pb leads to whisker mitigation. To date, a good non-toxic elemental alternative to Pb that would mitigate whiskers remains elusive. In this work, a 50–100 nm In electroplated layer was incorporated into a 1-μm-thick electroplated Sn on a pure Cu substrate. In order to permit diffusion of In into Sn, heat treatments (HTs) between 125°C and 160°C were performed. ...
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#1E. K. Snipes (AU: Auburn University)H-Index: 2
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Last. M. J. Bozack (AU: Auburn University)H-Index: 13
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In 2006, the European Union restricted lead (Pb) to > 0.1% (by weight) in electronics. This caused a renewal of interest in Sn whiskers, as the absence of Pb in Sn films had been known for years to promote Sn whisker growth. The early work on Sn whiskers had suggested that elements other than Pb may suppress whiskers. Bi was chosen as an attractive candidate, as it has similar phase formation behavior to Pb, i.e., low solubility, eutectic formation, and no intermetallic compounds with Sn. In thi...
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#1Jendrik Stein (MPG: Max Planck Society)H-Index: 3
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Abstract A wafer-curvature method has been developed to subject thin films, deposited on (Si) substrates, to well defined and controllable loads in a contact-free manner. To this end, a custom-made glass pan (i.e. a roof-less cylinder with a connection piece for vacuum tubes) connected to a needle valve, a vacuum pump and a pressure gauge has been used as an experimental setup. By fixing the coated Si wafer on top of the glass cylinder and evacuating the glass cylinder to a defined low-pressure,...
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#1Chien-Hao Su (NCU: National Central University)H-Index: 2
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This study sought to clarify the relationship between cracks in surface oxide layers and the growth behavior of tin whiskers. The number, length, and total volume of extrusions were precisely calculated and residual stress was measured using synchrotron radiation x-ray diffractometry. The aim was to elucidate the influence of stress on the driving force and flux involved in atomic diffusion. The distance between weak spots was shown to be the most significant factor involved in the growth of whi...
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#1Feng-Chih Hsu (NCHU: National Chung Hsing University)H-Index: 2
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A temperature controlled tensile testing was performed to investigate the influence of external stress on the growth of an interfacial Cu-Sn IMC layer. The test specimens were prepared by depositing 25 μm layers of tin atop of copper substrate using electroplating. Samples were then clamped in a micromechanical testing apparatus integrated with a furnace. Experiments were carried out using load feedback control to provide constant load on the specimens with the stress level of 50, 100 and 150 MP...
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#1Erika R. Crandall (AU: Auburn University)H-Index: 5
Since Sn oxidizes readily once deposited, oxygen exposure and the subsequent Sn oxides formed play a significant role in whisker growth. Many studies have demonstrated that Sn whisker growth is enhanced by exposure to oxygen and high relative humidity conditions [1, 2], especially near regions of surface corrosion.
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