Crystal Plasticity Finite-Element Analysis of Deformation Behavior in Multiple-Grained Lead-Free Solder Joints

Darbandi, Payam; Bieler, T. R.; Pourboghrat, Farhang; Lee, Tae‐Kyu

doi:10.1007/s11664-012-2339-4

Cited by 54 publications

(29 citation statements)

References 27 publications

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“…In this sense, a large nucleation undercooling for tin might be preferable as it reduces the eutectic IMC particle size, generates a small interphase spacing and produces many Sn grain boundaries from interlaced dendrites even though the number of Sn grains is small. However, there are also significant reliability issues associated with a small number of Sn grains with random orientation relative to the joint [17]. A joint containing few Sn orientations will have highly anisotropic properties because Sn has highly directional thermophysical properties [18].…”

Section: Introductionmentioning

confidence: 99%

“…A joint containing few Sn orientations will have highly anisotropic properties because Sn has highly directional thermophysical properties [18]. For example, the coefficient of thermal expansion [19], elastic stiffness [20], diffusion coefficient of common solutes [21] and plasticity [17] are all strongly direction dependent in Sn. Furthermore, if the few Sn grains are oriented differently in each joint, then the behaviour of each joint is unique.…”

Section: Introductionmentioning

confidence: 99%

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Nucleation and Growth of Tin in Pb-Free Solder Joints

Gourlay

Belyakov

et al. 2015

JOM

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The solidification of Pb-free solder joints is overviewed with a focus on the formation of the Sn grain structure and grain orientations. Three solders commonly used in electronics manufacturing, Sn-3Ag-0.5Cu, Sn-3.5Ag and Sn-0.7Cu-0.05Ni, are used as case studies to demonstrate that growth competition between primary dendrites and eutectic fronts during growth in undercooled melts is important in Pb-free solders, and that a metastable eutectic containing NiSn4 forms in Sn-3.5Ag/Ni joints. Additionally, it is shown that the substrate (metallization) has a strong influence on the nucleation and growth of tin. We identify Co, Pd and Pt substrates as having potential to control solidification and microstructure formation. In the case of Pd and Pt substrates, Sn is shown to nucleate on the PtSn4 or PdSn4 IMC reaction layer at relatively low undercooling of ~4K, even for small solder ball diameters down to <200 m. IntroductionThe transition to Pb-free electronic interconnections has been underway for more than a decade and despite the exemptions to the RoHS Directive there are few applications where Pb-free solders are not being used. At the same time, electronic packaging technologies have been advancing and there is an ongoing need to develop next-generation Pb-free solders and substrates that are better suited to smaller joints that can operate at higher temperature and that are more reliable.The most commonly used Pb-free solders are hypoeutectic or near-eutectic compositions from the Sn-Ag-Cu (SAC), Sn-Ag or Sn-Cu-Ni alloy systems. These compositions solidify with significant differences to the near-eutectic Sn-Pb solders used previously. For example, where the Sn-37Pb

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nucleation and Growth of Tin in Pb-Free Solder Joints

Gourlay

Belyakov

et al. 2015

JOM

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“…Fig.4 also compares the number of independent grains in 0.7Cu-0.05Ni-xBi with the number of grains found in Sn-3Ag-0.5Cu/Cu solder joints. We know that solder joint reliability issues might be associated with a small amount of βSn grains with random orientation relative to the joint [18]. This is due to highly anisotropic properties of βSn such as coefficient of thermal expansion, diffusion coefficient of common solutes, plasticity etc.…”

Section: A B Cmentioning

confidence: 99%

Influence of Bi additions on the distinct βSn grain structure of Sn-0.7Cu-0.05Ni-xBi (x = 0–4wt%)

Belyakov

Nishimura

Sweatman

et al. 2016

2016 International Conference on Electronics Packaging (ICEP)

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Abstract-Effects of Bi addition to the Ag-containing leadfree solders have been the focus of a considerable amount of past investigations, however, influence of Bi on Sn-Cu-Ni system has not been studied so extensively. In the present study we aimed to reveal the influence of Bi on microstructure formation of Sn-0.7Cu-0.05Ni/Cu solder joints both in the bulk and at the interface. It is shown that (i) Sn-0.7Cu-0.05Ni solidifies to produce a markedly different grain structure to Ag-containing lead-free alloys; (ii) Bi additions to Sn-0.7Cu-0.05Ni had no discernible effect neither on the βSn grain structure nor on (Cu,Ni)6Sn5 interfacial intermetallic layers or primary intermetallic crystals in solder joints.

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“…Recent anisotropic crystal plasticity models [6,31] have advocated for the use of slip systems 1-5,7,10,12 and the (110) [110]. In these models, they use a common yield stress for all the slip systems with less favorable slip systems assigned a lower hardening rate.…”

Section: Plastic Anisotropymentioning

confidence: 99%

“…If we assume, as is done in [6,31], that each slip system has the same critical resolved shear stress, then the Schmid factor determines the relative strength of the tin grains in uniaxial tension. However, the loading in the tin whisker problem is not uniaxial tension and thus we need a stress projection, factor similar to the Schmid factor, for biaxial loading.…”

Section: Plastic Anisotropymentioning

confidence: 99%

Modeling tin whisker growth.

Weinberger¹

2013

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Tin, lead, and lead-tin solders are the most commonly used solders due to their low melting temperatures. However, due to the toxicity problems, lead must now be removed from solder materials. This has lead to the re-emergence of the issue of tin whisker growth. Tin whiskers are a microelectronic packaging issue because they can lead to shorts if they grow to sufficient length. However, the cause of tin whisker growth is still not well understood and there is lack of robust methods to determine when and if whiskering will be a problem. This report summarizes some of the leading theories on whisker growth and attempts to provide some ideas towards establishing the role microstructure plays in whisker growth.3

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Crystal Plasticity Finite-Element Analysis of Deformation Behavior in Multiple-Grained Lead-Free Solder Joints

Cited by 54 publications

References 27 publications

Nucleation and Growth of Tin in Pb-Free Solder Joints

Nucleation and Growth of Tin in Pb-Free Solder Joints

Influence of Bi additions on the distinct βSn grain structure of Sn-0.7Cu-0.05Ni-xBi (x = 0–4wt%)

Modeling tin whisker growth.

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