Finite element modeling on electromigration of solder joints in wafer level packages

Dandu, P.R. Veera; Fan, Xuejun; Liu, Y.; Diao, Ce

doi:10.1016/j.microrel.2009.12.003

Cited by 20 publications

(11 citation statements)

References 16 publications

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“…Consequently, the cathode end of the material gets depleted while the anode end accumulates, increasing resistance over time and possibly leading to device failure. The factors affecting electromigration have been studied and it is believed that current density, temperature, and solder joint composition had a significant influence on electromigration [3][4][5]. In addition, the microstructure of the solder joint also has a significant effect on the electromigration which has attracted many researchers' attention [6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Effect of Grain Structure and Ni/Au-UBM Layer on Electromigration-Induced Failure Mechanism in Sn-3.0Ag-0.5Cu Solder Joints

Zhang

Wang

et al. 2022

Micromachines

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The development of advanced electronic devices leads to highly miniaturized interconnect circuits (ICs), which significantly increases the electromigration (EM) phenomenon of solder and circuits due to higher current density. The electromigration of solder joints under high current density has become a severe reliability concern in terms of microelectronic product reliability. The microstructure of the solder plays an important role in the electromigration induced degradation. In this study, Sn-3.0Ag-0.5Cu solder bumps with Ni/Au under bump metallization (UBM) layer were fabricated and electromigration acceleration tests were conducted under current density of 1.4 × 104 A/cm2 and 120 °C to investigate the effect of grain structure and Ni/Au-UBM layer on EM-induced failure. Grain structures of solder bumps were determined by utilizing the Electron Backscatter Diffraction (EBSD) technique, and single-crystal solder, single-crystal dominated solder, and polycrystalline solder are observed in different test samples. According to the Scanning Electron Microscope (SEM) images, it is observed that the Ni/Au-UBM layer of the Cu pad can inhibit atom diffusion between solder bump and Cu pad, which reduces the consumption of Cu pad but causes a large void and crack at the interface. The EM lifetime of single crystal solder bumps is lower than that of polycrystalline solder bumps when the c-axis of single crystal solder bumps is perpendicular to the electron flow direction. Additionally, the single crystal structure will increase the brittleness of the solder bump, and cracks are easily generated and expanded under the stress caused by the mismatch of thermal expansion coefficients between the solder bump and Ni/Au-UBM layer near Cu pad. Polycrystalline solder bumps with a higher misorientation angle (15–55°) have a higher atom diffusion rate, which will result in the acceleration of the EM-induced failure.

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Section: Introductionmentioning

confidence: 99%

Effect of Grain Structure and Ni/Au-UBM Layer on Electromigration-Induced Failure Mechanism in Sn-3.0Ag-0.5Cu Solder Joints

Zhang

Wang

et al. 2022

Micromachines

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“…Except above mentioned works, there are many papers with detailed numerical analysis and results, but some of the coupling terms in those governing equations are missing in one way or another. [17][18][19][20][21][22][23][24]. Until recently, a general coupling theory for electromigration has been developed, in which all important physical fields and its effects on electromigration are considered and fully coupled.…”

Section: Introductionmentioning

confidence: 99%

Implementation of General Coupling Model of Electromigration in ANSYS

Cui

Fan

Zhang

2020

2020 IEEE 70th Electronic Components and Technology Conference (ECTC)

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In this paper, a recently developed theorygeneral coupling model of electromigration, is implemented in ANSYS. We first identify several errors provided in ANSYS manuals for electromigration modeling. Then the general coupling model is implemented in ANSYS and the detailed description is presented. Finally, a 1-D confined metal line with a perfectly blocking condition is presented as a benchmark problem, in which the finite element solutions are in excellent agreement with the analytical solutions.

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“…Singh et al developed a 3D finite-element model for predicting the critical conditions to nucleate electromigration or stressinduced voids in interconnects, where they incorporate a cohesive zone model in the interfaces in order to model surface separation and mass diffusion in the surfaces [22]. Liu and coworkers have done extensive work in developing a 3D finite-element model for predicting void formation due to electromigration and reliability in wafer level packages [23][24][25][26][27][28]. While the above models have been able to provide some insight into where voids are likely to form and the effect of line geometry, current density, and temperature on void formation and failure, these models do not account for microstructure nor do they account for the strong anisotropy present in Sn-based solder.…”

Section: Introductionmentioning

confidence: 99%

Effect of Microstructure on Electromigration-Induced Stress

Maniatty

Liu

et al. 2015

Journal of Applied Mechanics

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In this paper, a finite element based simulation approach for predicting the effect of microstructure on the stresses resulting from electromigration-induced diffusion is described. The electromigration and stress-driven diffusion equation is solved coupled to the mechanical equilibrium and elastic constitutive equation, where a diffusional inelastic strain is introduced. Here, the focus is on the steady state, infinite life case, when the current-driven diffusion is balanced by the resulting stress gradient. The effect of the crystal orientation in Sn-based solder joints on the limiting current density for an infinite life is investigated and compared to experimental observations in the literature. The effect of the grain structure for Al interconnect lines on the dominant diffusion path and estimates for the effective charge number for two different diffusion paths in Al interconnects determined by matching simulations to experimental measurements of elastic strain components in the literature are also presented.

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Finite element modeling on electromigration of solder joints in wafer level packages

Cited by 20 publications

References 16 publications

Effect of Grain Structure and Ni/Au-UBM Layer on Electromigration-Induced Failure Mechanism in Sn-3.0Ag-0.5Cu Solder Joints

Effect of Grain Structure and Ni/Au-UBM Layer on Electromigration-Induced Failure Mechanism in Sn-3.0Ag-0.5Cu Solder Joints

Implementation of General Coupling Model of Electromigration in ANSYS

Effect of Microstructure on Electromigration-Induced Stress

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