Kirkendall voids at Cu/solder interface and their effects on solder joint reliability

Mei, Z.; Ahmad, Mudasir; Hu, Mason; Ramakrishna, Gnyaneshwar

doi:10.1109/ectc.2005.1441298

Cited by 47 publications

(35 citation statements)

References 4 publications

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“…Figure 2 shows an SEM imaging result of a solder and pad after the ageing time of 160 h and 350 h. No significant dissipation of Cu was found in pad after ageing for 160 h, and less IMCs and Kirkendall voids were found at the interface; in contrast, figure 2 (b) shows us a completely different result: the pad was consumed heavily, and large number of IMCs are found to be distributed uniformly between the pad and the solder. With the help of EDX and EBSD analysis, the IMCs close to solder are identified as Cu6Sn5 and Cu3Sn, in agreement with the results published in the literature [3,10,11]. We also find that Kirkendall voids in Cu3Sn are mostly generated next to the Cu pad, whereas they rarely are observed in the region far away from the pad.…”

Section: Thermal Ageing Experiments On Bga Structuresupporting

confidence: 79%

“…Feng Gao et al calculated and compared the self-diffusion rates of Cu and Sn in Cu3Sn by MD simulation and verified that the large difference in diffusivity between Cu and Sn is the main cause of Kirkendall void formation within the Cu3Sn layer in lead-free solder joints [10]. According to the results of Zequn Mei et al, most voids in Cu3Sn are centralized near the interface with the Cu substrate [11], which cannot be explained merely by the difference between the diffusivity of Cu and Sn in Cu3Sn. Thus, the diffusivity of atoms near the interface should be investigated separately.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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: Thermal Ageing Experiments On Bga Structuresupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

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

View full text Add to dashboard Cite

show abstract

“…This intermetallic compound is stiffer and brittle than the bulk solder and it could make the solder joint brittle and eventually lead to cracking even at lower loads than expected. [Mei et al (2005); Kim et al (2010)]. This observation of the brittle intermetallic phase may not have been possible without the high-energy Synchrotron X-ray beam of submicron size.…”

Section: Microstructural Evaluation Of the Solder Joint Of A Crystallmentioning

confidence: 99%

Probing Phase Transformations and Microstructural Evolutions at the Small Scales: Synchrotron X-ray Microdiffraction for Advanced Applications in 3D IC (Integrated Circuits) and Solar PV (Photovoltaic) Devices

Radchenko

Tippabhotla

Tamura

et al. 2016

Journal of Elec Materi

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Local crystal orientation, lattice distortion and phase transformations can all be probed using submicron size x-ray beam and Laue diffraction. Fast data collection provided by state-of-the-art area detectors at synchrotron facilities and new pattern indexing algorithms optimized for speed make it possible to map large portions of a sample in a reasonable amount of time and get quantitative images of its microstructure in near real time. This technique is particularly suitable for studying the mechanical and microstructural properties of inhomogeneous multi-phase polycrystalline samples. A recent development is Laue diffraction phase mapping which provides quantitative phase distribution in complex crystalline materials. This article will explore the recent developments in that respect at the Advanced Light Source, illustrated with a few advanced applications in the microelectronics, phase-change memory and solar PV devices/systems and propose as the underlying theme, the technique's unique capability to unravel insights that are otherwise not possible or at least impractical to obtain otherwise, and thus enabling the next generation of devices/systems.

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“…Subsequently, extensive research and development efforts have been focused on the SnAg-Cu system to evaluate the reliability risk factors associated with SAC solder joints, compared to the well-established Pb-containing solder joints [19][20][21][22][23][24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

“…These new findings have also closely related with the reliability issues of Sn-rich solder joints. To name a few items, such as excessive Cu consumption [26], easy fatigue crack growth along large Ag 3 Sn plates [16], chip-joining issues due to large undercooling [33], void formation and drop impact failure [22][23][24], crystal-orientation effects on thermal fatigue [28] and electromigration [34], and others.…”

Section: Introductionmentioning

confidence: 99%

‘Effects of Minor Alloying Additions on the Properties and Reliability of Pb‐Free Solders and Joints’

Kang¹

2012

Lead‐Free Solders: Materials Reliability for Electronics

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Since July, 2006, following the EUs RoHS legislation, the consumer electronics industry has been offering 'green' products by eliminating Pb-containing solders and other toxic materials. This transition has been relatively smooth, because the reliability requirements are less stringent. However, the Pb-free transition for high-performance electronic systems (such as servers and telecommunication) is still on-going due to their rigorous reliability requirements. For example, the research and development efforts to implement Pb-free flipchip interconnections for high-end applications are still very active.In this chapter, the recent progress in Pb-free solder development, especially minor alloy additions to Sn-rich solders is reviewed in light of improving various physical, mechanical, metallurgical or electrical properties of solder joints. The topics to be discussed include those such as control of undercooling, microstructure, interfacial reactions, or void formation, as well as enhancing impact resistance, electromigration, and other mechanical properties.

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Kirkendall voids at Cu/solder interface and their effects on solder joint reliability

Cited by 47 publications

References 4 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

Probing Phase Transformations and Microstructural Evolutions at the Small Scales: Synchrotron X-ray Microdiffraction for Advanced Applications in 3D IC (Integrated Circuits) and Solar PV (Photovoltaic) Devices

‘Effects of Minor Alloying Additions on the Properties and Reliability of Pb‐Free Solders and Joints’

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