Creep phenomena in lead-free solders

Igoshev, V. I.; Kleiman, Jacob

doi:10.1007/s11664-000-0150-0

Cited by 52 publications

(29 citation statements)

References 22 publications

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“…A superficial study of this plot suggests that the Dorn equation is quite Adeva et al, 14) Mathew et al 15) and others 16,17) have measured much lower activation energies at lower temperature. The measured activation energies are close to those for lattice diffusion (∼100 kJ/mol 18,19) ) and dislocation pipe diffusion (40-60 kJ/mol 14,20,21) ) suggesting that the dominant activation step changes from lattice to pipe diffusion as the temperature drops.…”

Section: Creep Behaviorsupporting

confidence: 52%

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 Behaviorsupporting

confidence: 52%

Anomalous Creep in Sn-Rich Solder Joints

2002

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“…Therefore, the experimental results cannot be explained by dislocation creep mechanisms only, and other factors affecting the creep rate of solder joint should be considered. 21 Based on the classic theory of dispersion strengthening, the increasing of the strength of solder can be attributed to the presence and distribution of fine reinforcements within the matrix and at the grain boundary of the solder matrix, which tend to alter the deformation characteristics of solder by impeding grain boundary sliding, while retarding dislocation movement in the solder matrix for the Sn-0.7Cu solder alloy, dispersed intermetallics, Cu 6 Sn 5 , may be considered as reinforcements, while for the Ag-particle-reinforced Sn-0.7Cu-based composite solder, the reinforcements are the Ag particles surrounded by the Ag 3 Sn intermetallic layer, except for Cu 6 Su 5 particles in the matrix. Thus, the creep stress exponent of the solder joint is higher than predicted by theoretical models, and the stress exponent of the Ag-particle-reinforced composite solder joint is increased to a much higher value.…”

Section: Resultsmentioning

confidence: 99%

Constitutive Relations for Creep in a SnCu-Based Composite Solder Reinforced with Ag Particles

Shi

Yan

Liu

et al. 2009

Journal of Elec Materi

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In the present work, the creep strain of the composite solder joint is measured using a stepped load creep test on a single specimen. Based on the creep strain tests, constitutive relations for the steady-state creep rate are determined for the Ag-particle-reinforced Sn-0.7Cu-based composite solder joint. In addition, creep strain tests on the Sn-0.7Cu solder joint are performed as a comparison. It is found that the activation energy of the Ag-particle-reinforced Sn-0.7Cu-based composite solder joint is higher than that of the Sn-0.7Cu solder joint. At the same time, the stress exponent of the Ag-particle-reinforced Sn-0.7Cu-based composite solder joint is higher than that of the Sn-0.7Cu solder joint. It is expected that the creep resistance of the Ag-particle-reinforced Sn-0.7Cu-based composite solder joint will be superior to that of the Sn-0.7Cu solder joint. Finally, the creep deformation mechanisms of the solder joint are discussed.

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“…1,2 However, the experimental data on the microstructural evaluation and the failure mechanism of solder joints made of this alloy, and even the results obtained for the bulk samples, published so far, are very controversial. [3][4][5][6] Creep deformation is the most common and important type of loading a solder joint undergoes. 1 Our previous paper 7 described the changes in microstructure of Sn-3.5%Ag solder alloy during creep deformation.…”

Section: Introductionmentioning

confidence: 99%