Forming mechanism and growth of Kirkendall voids of Sn/Cu joints for electronic packaging: A recent review

Wang, Jianbo; Chen, Jieshi; Zhang, Lixia; Zhang, Zhiyuan; Han, Yuzhu; Hu, Xiaowu; Lü, Hao; Zhang, Shuye

doi:10.1016/j.jajp.2022.100125

Cited by 30 publications

(15 citation statements)

References 93 publications

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“…As can be seen in Figure 13(c)–(d), the reaction of Sn63Pb37 solder with the Cu substrate at the joint also forms a continuous Cu 6 Sn 5 , and many white Pb-rich phases appear in the solder (Tu and Zeng, 2001). This might be due to Cu diffusion from the substrate into the solder, where it reacts with Sn to form Cu 6 Sn 5 (Wang et al , 2022c). A large amount of Sn is consumed in the process, resulting in a low local Sn concentration, leading to a Pb-rich phase.…”

Section: Resultsmentioning

confidence: 99%

Early wetting and interfacial behavior of Sn-based solder on copper substrates with different roughness

Han,

Chen,

Zhang

et al. 2023

SSMT

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Purpose This paper aims to investigate the effect of solder composition and roughness on early wetting behavior and interfacial reaction under atmospheric conditions. Design/methodology/approach High-speed photography is used to observe the early wetting and spreading process of the solder on the substrate in real time. The morphology of intermetallic compounds (IMCs) was observed by scanning electron microscopy, and the composition of IMCs micro bumps was determined by energy dispersive spectroscopy. Findings With a roughness range of 0.320–0.539 µm, the solder is distributed in an elliptical trilinear pattern along the grinding direction. With a roughness range of 0.029–0.031 µm, the solder spreads in the direction of grinding and perpendicular, forming a perfect circle (except in the case of Sn63Pb37 solder). The effect of three types of solder on early wettability is Sn63Pb37 > Sn96.5Ag3Cu0.5 > Sn. The wetting behavior is consistent with the Rn∼t model. The rapid spreading stage (Stage I) is controlled by the interfacial reaction with n1 values between 2.4 and 4. The slow spreading stage (stage II) is controlled by diffusion with n2 values between 4 and 6.7. The size of Cu6Sn5 formed on a rough substrate is greater than that produced on a smooth substrate. Originality/value Investigating the effect of solder composition and roughness on early wettability. This will provide a powerful guide in the field of soft brazing.

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Section: Resultsmentioning

confidence: 99%

Early wetting and interfacial behavior of Sn-based solder on copper substrates with different roughness

Han,

Chen,

Zhang

et al. 2023

SSMT

Self Cite

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“…Gibb's isotherm theory stated that the interfacial energy and free energy barrier declined due to S segregation because it helps in the formation of the voids. [ 25 ]…”

Section: Nucleation Of Kvsmentioning

confidence: 99%

“…Researchers stated three points for the nucleation of the voids: 1) vacancy creation, 2) vacancy accumulation, and 3) void nucleation. The imbalance problem is resolved by a vacancies flux that is represented as the KE and vacancy flux in the Sn/Cu reaction process is governed by Equation () [ 13,25,101,102 ]

J_{\text{V}} + J_{\text{A}} = 0

and

J_{\text{A}} = \textrm{ } \sum J_{\text{A} , \text{P}}^{\text{F}} \text{ }

where…”

Section: Evaluation Of Kvsmentioning

confidence: 99%

“…J. Wang et al [25] and other researchers stated that three factors contribute to the development of KVs, which are 1) Cu atoms diffusion route, 2) the addition of impurities (different types) in the substrates, and 3) development of stresses at the Cu 3 Sn/Cu interface. Some researchers [42][43][44] have reported that interfacial voids are connected to the allocation of residual stress developed by phase changes.…”

Section: Nucleation Of Kvsmentioning

confidence: 99%

“…[10,14,16,17,[22][23][24] J. Y. Kim et al [20] study shows that KVs are initiated at the Cu 3 Sn/Cu interface due to the segregation of residual S and these voids are propagated due to the KE. J. Wang et al [25] also examined that larger grain sizes inhibited the formation of the void at the interface.…”

Section: Nucleation Of Kvsmentioning

confidence: 99%

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Nucleation and Location of Kirkendall Voids at the Tin‐Based Solder/Copper Joint: A Review

Pal

Bajaj²

2023

Adv Eng Mater

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Void nucleation is a critical issue in wetting because it negatively impacts the solder joint and diminishes its electrical and mechanical properties. Generally, the Kirkendall effect (unbalanced diffusion) and Kirkendall voids (KVs) are developed due to dissimilar diffusivities of species (Cu and Sn) in a diffusion process. However, voids are also nucleated in the supersaturating condition, creating an additional position at or inside the “Kirkendall voids” interface. Various factors (surface modification, reinforcement of fourth elements, substrate type, and impurities) and the environment also support the nucleation of voids. Many researchers have discussed that KVs are nucleated into to intermetallic compounds layers. Reviewing the significant parameters for developing the KV in solid–liquid and solid–solid conditions is essential. Hence, in this review, the potential process of development of the KVs, concepts of thermodynamics, chemical reactions, and growth kinetics are developed. The position and reduction of KVs nucleation are also explained in this paper.

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Electrical Resistivity of Lead-Free Solders Reinforced by Carbon Nanospheres

Plevachuk,

Poverzhuk,

Svec

et al. 2024

Int J Thermophys

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Electrical resistivity of the nanocomposites Sn96.5Ag3Cu0.5 and Sn95,5Ag3,8Cu0,7 lead-free solder alloys with minor admixtures of carbon nanospheres (0.05 wt%) was measured in a wide temperature range, including a melting-solidification region. Influence of the carbon nanospheres content on electrical resistivity values has been analyzed. Carbon nanospheres were obtained by electrical discharge method from diesel fuel, cyclohexane, and aviation kerosene. The matrix samples were produced by planar flow casting technique in the form of thin ribbons. Electrical resistivity measurements were performed using four-probe method. Hysteresis between the heating and cooling electrical resistivity curves relates to the non-equilibrium solidification.

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Forming mechanism and growth of Kirkendall voids of Sn/Cu joints for electronic packaging: A recent review

Cited by 30 publications

References 93 publications

Early wetting and interfacial behavior of Sn-based solder on copper substrates with different roughness

Early wetting and interfacial behavior of Sn-based solder on copper substrates with different roughness

Nucleation and Location of Kirkendall Voids at the Tin‐Based Solder/Copper Joint: A Review

Electrical Resistivity of Lead-Free Solders Reinforced by Carbon Nanospheres

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