Effects of Electrical Current and External Stress 
on the Electromigration of Intermetallic Compounds 
Between the Flip-Chip Solder and Copper Substrate

Chen, Wei-Jhen; Lee, Yue-Lin; Wu, Ti-Yuan; Chen, Tzu-Ching; Hsu, Chih-Hui; Lin, Ming-Tzer

doi:10.1007/s11664-017-5685-4

Cited by 17 publications

(7 citation statements)

References 29 publications

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“…In other words, with the increase of temperature, the effect of stress on the diffusivity of Cu part is more significant, and it has the same tendency as the atoms in Cu3Sn. Thus, a conclusion can be made that stress will influence the diffusivity of atoms in the Cu-Cu3Sn structure: compressive stress accelerates the diffusion of atoms near the interface whereas tensile stress inhibits it, especially for the condition of higher temperature, which is well proved by the experimental result from Chen, W. J. et al [31]. This huge difference of atoms' diffusivity induced by different loading conditions would cause the nonuniform consumption of pad.…”

Section: Figure 4 Molecular Model With Load Vectormentioning

confidence: 89%

A Molecular Dynamics Investigation of the Effect of Pressure and Orientation on the Cu Consumption in Cu-Cu3Sn Interface under Isothermal Ageing and Its Dissipative Mechanisms during Traction

Liang¹,

Zhang²,

Xu³

et al. 2018

Preprint

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Abstract:In this paper, the nanoscale dissipative mechanisms of a Cu pad in a Ball Grid Array (BGA) packaging structure during isothermal ageing and uniaxial tension were investigated by the molecular dynamics (MD) method and experiments. From the result of the isothermal ageing test, a nonuniform consumption of Cu and large amount of Kirkendall voids were observed at the interface of Cu and Cu3Sn. To study the effect of pressure and orientation on this phenomenon, MD simulations were conducted on four types of Cu-Cu3Sn interface structures with different orientations of Cu. By comparing the diffusion coefficients of atoms in those cases, it was found that the tensile stress would inhibit the diffusion of atoms, whereas compressive stress would accelerate it, and this would be more significant under a larger magnitude of stress and temperature. Note that, in the model with the (101) surface Cu at the interface, both Cu and Cu3Sn have a higher diffusion coefficient compared with the model with (001) surface Cu. Thus, the orientation of Cu will also contribute to the uniform consumption of the pad. Uniaxial tension simulation combined with DXA and CSP analyses on those models also shows the model with (001) surface Cu has a greater mechanical reliability in our simulations and related experiments.

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Section: Figure 4 Molecular Model With Load Vectormentioning

confidence: 89%

A Molecular Dynamics Investigation of the Effect of Pressure and Orientation on the Cu Consumption in Cu-Cu3Sn Interface under Isothermal Ageing and Its Dissipative Mechanisms during Traction

Liang¹,

Zhang²,

Xu³

et al. 2018

Preprint

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show abstract

“…However, at present, there are few devices that can achieve ideal electromigration conditions. In a relatively ideal electromigration test environment, Chen et al [ 28 ] studied the relationship between electromigration and current density in Cu/Sn/Cu solder joints and concluded that significant electromigration polarity was observed in the Cu/Sn/Cu solder joints at current densities of 10 4 A/cm 2 and above [ 29 ], suggesting that the critical current density of Sn-based lead−free solder joints may be around 10 4 A/cm 2 . Yao et al [ 30 ] conducted a current loading test on Cu/Sn3.8Ag0.7Cu/Cu solder joints under the condition of a critical current density of 10 4 A/cm 2 .…”

Section: Introductionmentioning

confidence: 99%

Study on Microstructure and Mechanical Properties at Constant Electromigration Temperature of Sn2.5Ag0.7Cu0.1RE0.05Ni-GNSs/Cu Solder Joints

Zhang

Gao

et al. 2023

Materials

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To solve the electromigration problem of micro−electronic connection solder joints, an ideal electromigration tester was designed, and the thickness of the intermetallic compounds (IMCs), average void diameter, grain orientation, failure, shear strength, and fracture path of Sn2.5Ag0.7Cu0.1RE0.05Ni−GNSs/Cu solder joints under constant−temperature electromigration were studied. The results indicate that the solder joints show evidence of typical electromigration polarity in the asymmetric growth of interfacial IMCs on the anode and cathode sides under the conditions of a current density ≥7 × 103 A/cm2 and an included angle between the c−axis of the β−Sn grains and the current direction θ ≤ 53.2°. The anode−side interfacial IMC is dominated by a Cu6Sn5 phase with a gradually increasing thickness, forming a Cu3Sn phase and showing evidence of microcracks. The Cu6Sn5 phase of the cathode−side interfacial IMC is gradually completely dissolved, and the growth of the Cu3Sn phase is accompanied by the formation of Kirkendall voids. The anisotropic diffusion of Cu atoms in the β−Sn of the micro−solder joints causes increased solder joint resistance and reduced shear strength. The shear fracture path of the solder joints moves from the cathode side near the IMC solder seam to the Cu3Sn interface. The shear fracture mechanism changes from ductile transgranular fracture dominated by β−Sn dimples to brittle fracture dominated by interfacial IMC cleavage and slip steps.

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“…The trend of miniaturization and the integration of electronic devices leads to the reduction of the size of solder joints [1,2]. Accordingly, the current density in the solder joints will increase dramatically [3].…”

Section: Introductionmentioning

confidence: 99%

The In-Situ Observation of Grain Rotation and Microstructure Evolution Induced by Electromigration in Sn-3.0Ag-0.5Cu Solder Joints

Chen

et al. 2020

Materials

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The in-situ observation of Sn-3.0Ag-0.5Cu solder joints under electromigration was conducted to investigate the microstructure and grain orientation evolution. It was observed that there was a grain rotation phenomenon during current stressing by in-situ electron backscattered diffraction (EBSD). The rotation angle was calculated, which indicated that the grain reorientation led to the decrease of the resistance of solder joints. On the other hand, the orientation of β-Sn played a critical role in determining the migration of Cu atoms in solder joints under current stressing migration. When the angle between the electron flow direction and the c-axis of Sn (defined as α) was close to 0°, massive Cu6Sn5 intermetallic compounds were observed in the solder bulk; however, when α was close to 90°, the migration of the intermetallic compound (IMC) was blocked but many Sn hillocks grew in the anode. Moreover, the low angle boundaries were the fast diffusion channel of Cu atoms while the high grain boundaries in the range of 55°–65° were not favorable to the fast diffusion of Cu atoms.

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Effects of Electrical Current and External Stress on the Electromigration of Intermetallic Compounds Between the Flip-Chip Solder and Copper Substrate

Cited by 17 publications

References 29 publications

A Molecular Dynamics Investigation of the Effect of Pressure and Orientation on the Cu Consumption in Cu-Cu3Sn Interface under Isothermal Ageing and Its Dissipative Mechanisms during Traction

A Molecular Dynamics Investigation of the Effect of Pressure and Orientation on the Cu Consumption in Cu-Cu3Sn Interface under Isothermal Ageing and Its Dissipative Mechanisms during Traction

Study on Microstructure and Mechanical Properties at Constant Electromigration Temperature of Sn2.5Ag0.7Cu0.1RE0.05Ni-GNSs/Cu Solder Joints

The In-Situ Observation of Grain Rotation and Microstructure Evolution Induced by Electromigration in Sn-3.0Ag-0.5Cu Solder Joints

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