Effect of isothermal aging and low density current on intermetallic compound growth rate in lead-free solder interface

Shen, Jun; Cao, Zhongming; Zhai, Dajun; Zhao, Mali; He, Peipei

doi:10.1016/j.microrel.2013.09.005

Cited by 11 publications

(5 citation statements)

References 26 publications

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“…In all simulations, the initially scallop-shaped interface between Cu 6 Sn 5 and Sn gradually transitions into a more planar morphology. This behavior has been observed experimentally during solid state aging of tin at different temperatures below the melting temperature [12,39,40]. During aging, the grain boundaries between the IMC grains remain vertical for IC1, whereas for IC2 and IC3, due to different IMC grain sizes, curved grain boundaries are obtained.…”

Section: Cusupporting

confidence: 65%

“…An isotropic von Mises plasticity model with hardening based on the dislocation density has been used for the Cu and Sn phases, while the IMC was assumed to behave elastically. It was found that the model qualitatively captures the transition from a scallop-like to a layered IMC morphology [12,39,40] and the linear growth dependence on time [8,41], as seen in experiments. We have also shown that the growth rate of the IMC depends on the grain boundary diffusion coefficient, a higher value will increase the grain boundary mobility and give a higher growth rate.…”

Section: Discussionmentioning

confidence: 64%

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Coupled diffusion-deformation multiphase field model for elastoplastic materials applied to the growth of Cu6Sn5

et al. 2016

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A coupled diffusion-deformation, multiphase field model for elastoplastic materials is presented. The equations governing the evolution of the phase fields and the molar concentration field are derived in a thermodynamically consistent way using microforce balance laws. As an example of its capabilities, the model is used to study the growth of the intermetallic compound (IMC) Cu 6 Sn 5 during room-temperature aging. This IMC is of great importance in, e.g., soldering of electronic components. The model accounts for grain boundary diffusion between IMC grains and plastic deformation of the microstructure. A plasticity model with hardening, based on an evolving dislocation density, is used for the Cu and Sn phases. Results from the numerical simulations suggest that the thickness of the IMC layer increases linearly with time and that the morphology of the IMC gradually changes from scallop-like to planar, consistent with previous experimental findings. The model predicts that plastic deformation occurs in both the Cu and the Sn layers. Furthermore, the mean value of the biaxial stress in the Sn layer is found to saturate at a level of −8 MPa to −10 MPa during aging. This is in good agreement with experimental data.

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Section: Cusupporting

confidence: 65%

Section: Discussionmentioning

confidence: 64%

Coupled diffusion-deformation multiphase field model for elastoplastic materials applied to the growth of Cu6Sn5

et al. 2016

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“…Simultaneously, the exaggerated IMC layer’s growth may also deteriorate the solder joints’ reliability [ 11 ]. Shen et al [ 12 ] also posited that the IMC layer rises with annealing time due to the solid-state diffusion taking place between Cu atoms from the Cu-pad and Sn from the bulk solder. The average thicknesses of Cu 3 Sn and Cu 6 Sn 5 at 180 °C are plotted as shown in Figure 5 .…”

Section: Resultsmentioning

confidence: 99%

Influence of 1.5 wt.% Bi on the Microstructure, Hardness, and Shear Strength of Sn-0.7Cu Solder Joints after Isothermal Annealing

et al. 2021

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This manuscript reports the isothermal annealing effect on the mechanical and microstructure characteristics of Sn-0.7Cu-1.5Bi solder joints. A detailed microstructure observation was carried out, including measuring the activation energy of the intermetallic compound (IMC) layer of the solder joints. Additionally, the synchrotron µX-ray fluorescence (XRF) method was adopted to precisely explore the elemental distribution in the joints. Results indicated that the Cu6Sn5 and Cu3Sn intermetallic layers thickness at the solder/Cu interface rises with annealing time at a rate of 0.042 µm/h for Sn-0.7Cu and 0.037 µm/h for Sn-0.7Cu-1.5Bi. The IMC growth’s activation energy during annealing is 48.96 kJ mol-1 for Sn-0.7Cu, while adding Bi into Sn-0.7Cu solder increased the activation energy to 55.76 kJ mol−1. The µ-XRF shows a lower Cu concentration level in Sn-0.7Cu-1.5Bi, where the Bi element was well dispersed in the β-Sn area as a result of the solid solution mechanism. The shape of the IMC layer also reconstructs from a scallop shape to a planar shape after the annealing process. The Sn-0.7Cu hardness and shear strength increased significantly with 1.5 wt.% Bi addition in reflowed and after isothermal annealing conditions.

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“…According to Fig. 5(b), the thickness of Cu 3 Sn and Cu 6 Sn 5 increased linearly with the square root of aging time, which meant the growth of Cu 3 Sn and Cu 6 Sn 5 was limited by the atomic d iffusion of Cu and Sn [12]. Vuorinen et al [13] determined the diffusion flu xes in the binary Sn-Cu system at 125 : , , where is the diffusion flu x of Sn in Cu6Sn5.…”

Section: Methodsmentioning

confidence: 99%

Effects of Cu orientation and stand-off-height on the microstructure of Cu/SnAgCu interface

Xiao

Liang

et al. 2014

2014 15th International Conference on Electronic Packaging Technology

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The effects of Cu orientation and stand-offheight on the microstructure and growth of IMCs in Cu/S nAgCu/Cu solder joints was investigated. Cu 6 Sn 5 and Cu 3 S n were the two key intermetallic compounds (IMCs) that formed at the interface. On (111) Cu substrate, prism-like Cu 6 Sn 5 grains could be observed after reflowing at 250 for 10s. On polycrystalline Cu substrate, only scallop-like Cu 6 Sn 5 grains formed and the grain size is smaller than that of (111) Cu. Then, samples were aged at 150 and the thickness of Cu 6 Sn 5 and Cu 3 Sn layers increased with the increasing aging time. We found that Cu 3 S n formed on (111) Cu substrate grew faster than that on polycrystalline Cu substrate , owing to Cu 3 S n columnar growth on (111) Cu and grain boundary diffusion control. After aging at 150 for 384 h, the IMC growing from the upper side and from the lower side touched each other in solder joints with 10 m SOH. Cu 6 Sn 5 stopped growing while Cu 3 Sn continued growing at the consumption of Cu 6 Sn 5 , resulting in the decrease of thickness of Cu 6 Sn 5 .

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Effect of isothermal aging and low density current on intermetallic compound growth rate in lead-free solder interface

Cited by 11 publications

References 26 publications

Coupled diffusion-deformation multiphase field model for elastoplastic materials applied to the growth of Cu6Sn5

Coupled diffusion-deformation multiphase field model for elastoplastic materials applied to the growth of Cu6Sn5

Influence of 1.5 wt.% Bi on the Microstructure, Hardness, and Shear Strength of Sn-0.7Cu Solder Joints after Isothermal Annealing

Effects of Cu orientation and stand-off-height on the microstructure of Cu/SnAgCu interface

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