Constitutive relations for tin-based solder joints

Darveaux, Robert; Banerji, K.

doi:10.1109/33.206925

Cited by 384 publications

(179 citation statements)

References 10 publications

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“…The stress exponents reported in the literature for Sn and Sn-rich solders scatter widely, from near 5 (Breen and Weertman 9) Darveaux and Banerji 22) ) to 10-11 (Yang et al, 23) Mavoori et al 24) ). In the present work, this whole range of stress exponents appears in the same data set, depending on…”

Section: Creep Behaviormentioning

confidence: 99%

Anomalous Creep in Sn-Rich Solder Joints

2002

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This paper discusses the creep behavior of example Sn-rich solders that have become candidates for use in Pb-free solder joints. The specific solders discussed are Sn-3.5Ag, Sn-3Ag-0.5Cu, Sn-0.7Cu and Sn-10In-3.1Ag, used in thin joints between Cu and Ni/Au metallized pads. The creep behavior of these joints was measured over the range 60-130 • C. The four solders show the same general behavior. At all temperatures their steady-state creep rates are separated into two regimes with different stress exponents (n). The low-stress exponents range from ∼3-6, while the high-stress exponents are anomalously high (7-12). Strikingly, the high-stress exponent has a strong temperature dependence near room temperature, increasing significantly as the temperature drops from 95 to 60 • C. The anomalous behavior of the solders appears to be due to the dominant Sn constituent. Joints of pure Sn have stress exponents, n, that change with stress and temperature almost exactly like those of the Sn-rich solder joints. Surprisingly, however, very similar behavior is found in Sn-10In-3.1Ag, whose primary constituent is γ -InSn. Research on creep in bulk samples of pure Sn suggests that the anomalous temperature dependence of the stress exponent is due to a change in the dominant mechanism of creep. Whatever its source, it has the consequence that conventional constitutive relations for steady-state creep must be used with caution in treating Sn-rich solder joints, and qualification tests that are intended to verify performance should be carefully designed.

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Section: Creep Behaviormentioning

confidence: 99%

Anomalous Creep in Sn-Rich Solder Joints

2002

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“…This process flow involved the die mounting, the wire bonding, the molding and the singulation. The EMC elements were then deactivated during die attach process at 175°C and this temperature is a reference for the minimum stress temperature [1][2][3] , as defined by the temperature profile step in Table 2. The EMC element was reactivated at molding temperature of 175°C and it was then cooled to 25°C.…”

Section: Resultsmentioning

confidence: 99%

Thermal-Mechanical Analysis of a Different Leadframe Thickness of Semiconductor Package under the Reflow Process

Abdullah¹,

Abdullah²,

Ariffin³

et al. 2009

American J. of Applied Sciences

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Abstract:The copper-based leadframe is practically proven effective in the thermal and reliability of a Quad Flat No Lead (QFN) three dimension (3D) stacked-die semiconductor package. Reducing the copper thickness is understood to present various thermal and reliability failure mode and mechanisms, such as die cracking and delamination. However, no in-depth study has been pursued in order to determine the capability of achieving the product requirements in terms of thermal and reliability in a 3D stacked-die package. The drive towards a Die-Free Package Cost (DFPC) reduction has led the authors to study the used of a thin leadframe in a QFN 3D stacked-die. Hence, the work presents basis for the qualification of a thin leadframe design and also to demonstrate the thermal and reliability performance. Finally, an extensive virtual thermal-mechanical prototyping has to be achieved in order to understand the physics of materials during the assembly and reliability testing of a 3D stacked-die package with a thin leadframe. This design rule was found to be developed in order to prevent a die crack occurrence between die and leadframe in the semiconductor package.

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“…However, observe that the activation energy for lattice self-diffusion 14 of tin in tin is 105-107 kJ/mol depending on crystallographic direction, and for lead in lead, 107-109 kJ/ mol.…”

Section: Causal Mechanismsmentioning

confidence: 99%

Viscoelastic behavior of 80In15Pb5Ag and 50Sn50Pb alloys: Experiment and modeling

Edwards¹,

Lakes

Nixon

2000

Journal of Applied Physics

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Dynamic and creep behavior of 80In15Pb5Ag and 50Sn50Pb were studied isothermally over nine decades of time and frequency. 80In15Pb5Ag was examined at Ϫ6, 21, and 50°C, and 50Sn50Pb was examined at 21°C. Viscoelastic behavior was observed at strains less than 10 Ϫ5 as a function of temperature and time/frequency. At the small strain used in the study, the alloys exhibit linear viscoelasticity rather than the viscoplasticity observed at larger strain. Viscoelasticity was subject to constitutive modeling. The creep followed a superposition of a stretched exponential and a power law in time, and an Arrhenius form in temperature. Behavior was thermorheologically simple over at least nine decades of true time and frequency.

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Constitutive relations for tin-based solder joints

Cited by 384 publications

References 10 publications

Anomalous Creep in Sn-Rich Solder Joints

Anomalous Creep in Sn-Rich Solder Joints

Thermal-Mechanical Analysis of a Different Leadframe Thickness of Semiconductor Package under the Reflow Process

Viscoelastic behavior of 80In15Pb5Ag and 50Sn50Pb alloys: Experiment and modeling

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