Influence of Ni on the refinement and twinning of primary Cu6Sn5 in Sn-0.7Cu-0.05Ni

Xian, J.W.; Salleh, Mohd Arif Anuar Mohd; Belyakov, S. A.; Su, Te Cheng; Zeng, Guang; Nogita, Kazuhiro; Yasuda, Hideyuki; Gourlay, C.M.

doi:10.1016/j.intermet.2018.08.002

Cited by 28 publications

(6 citation statements)

References 52 publications

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“…As depicted in Figure 4 , it can be seen that the Cu 6 Sn 5 primary intermetallics formed in various morphologies that consist of a mixture of a hexagonal rod, hollow faceted hexagonal rods, and “in-plane” branched form. Several studies reported that the different morphologies of Cu 6 Sn 5 could be influenced by different factors, including the Cu content, the undercooling, and the cooling rate [ 13 , 14 , 15 ]. In this research, it is observed that the formation of primary Cu 6 Sn 5 crystals in a joint of Sn-3.5Ag/Cu-OSP can be categorized into three solidified locations based on reflow cycles: (i) first reflow, (ii) from second to fourth reflow, and (iii) from fifth to sixth cycle; these will be discussed later.…”

Section: Resultsmentioning

confidence: 99%

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Effects of Multiple Reflow on the Formation of Primary Crystals in Sn-3.5Ag and Solder Joint Strength: Experimental and Finite Element Analysis

et al. 2023

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The growth and formation of primary intermetallics formed in Sn-3.5Ag soldered on copper organic solderability preservative (Cu-OSP) and electroless nickel immersion gold (ENIG) surface finish after multiple reflows were systematically investigated. Real-time synchrotron imaging was used to investigate the microstructure, focusing on the in situ growth behavior of primary intermetallics during the solid–liquid–solid interactions. The high-speed shear test was conducted to observe the correlation of microstructure formation to the solder joint strength. Subsequently, the experimental results were correlated with the numerical Finite Element (FE) modeling using ANSYS software to investigate the effects of primary intermetallics on the reliability of solder joints. In the Sn-3.5Ag/Cu-OSP solder joint, the well-known Cu6Sn5 interfacial intermetallic compounds (IMCs) layer was observed in each reflow, where the thickness of the IMC layer increases with an increasing number of reflows due to the Cu diffusion from the substrate. Meanwhile, for the Sn-3.5Ag/ENIG solder joints, the Ni3Sn4 interfacial IMC layer was formed first, followed by the (Cu, Ni)6Sn5 IMC layer, where the formation was detected after five cycles of reflow. The results obtained from real-time imaging prove that the Ni layer from the ENIG surface finish possessed an effective barrier to suppress and control the Cu dissolution from the substrates, as there is no sizeable primary phase observed up to four cycles of reflow. Thus, this resulted in a thinner IMC layer and smaller primary intermetallics, producing a stronger solder joint for Sn-3.5Ag/ENIG even after the repeated reflow process relative to the Sn-3.5Ag/Cu-OSP joints.

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Section: Resultsmentioning

confidence: 99%

“…These results aligned with our previous work, where the intermetallics formed in the SAC305 reflowed on the immersion tin (ImSn) were smaller. Note that they resulted in a higher solder joint strength than the immersion silver (ImAg) surface finish [ 14 ].…”

Section: Resultsmentioning

confidence: 99%

Effects of Multiple Reflow on the Formation of Primary Crystals in Sn-3.5Ag and Solder Joint Strength: Experimental and Finite Element Analysis

et al. 2023

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“…Moreover, the presence of elemental Ni in molten Sn matrix can dramatically reduce the solubility of Cu, which can result in the massive and dispersive precipitation of Cu and Ni atoms in the form of (Cu,Ni) 6 Sn 5 particles, and thus induce the refining of the (Cu,Ni) 6 Sn 5 phase [27,28]. The fine scale polycrystalline structure may further improve the diffusion rate of Ni through the material by increasing the number of available grain boundary diffusion paths [29]. Moreover, the Cu-Ni alloy has a lower melting point than that of pure Ni, which means a higher dissolution rate of Cu-Ni alloy into the molten Sn matrix would be expected.…”

Section: Metallurgic Reaction Mechanism Of Cu Jointsmentioning

confidence: 99%

Microstructure and mechanical properties of Cu joints soldered with a Sn-based composite solder, reinforced by metal foam

Huang

et al. 2020

Journal of Alloys and Compounds

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In this study, Ni foam, Cu coated Ni foam and Cu-Ni alloy foams were used as strengthening phases for pure Sn solder. Cu-Cu joints were fabricated by soldering with these Sn-based composite solders at 260 °C for different times. The tensile strength of pure Sn solder was improved significantly by the addition of metal foams, and the Cu-Ni alloy/Sn composite solder exhibited the highest tensile strength of 50.32 MPa. The skeleton networks of the foams were gradually dissolved into the soldering seam with increasing soldering time, accompanied by the massive formation of (Cu,Ni) 6 Sn 5 phase in the joint. The dissolution rates of Ni foam, Cu coated Ni foam and Cu-Ni alloy foams into the Sn matrix increased successively during soldering. An increased dissolution rate of the metal foam leads to an increase in the Ni content in the soldering seam, which was found to be beneficial in refining the (Cu,Ni) 6 Sn 5 phase and inhibiting the formation of the Cu 3 Sn IMC layer on the Cu substrate surface. The average shear strength of the Cu joints was improved with increasing soldering time, and a shear strength of 2 61.2 MPa was obtained for Cu joints soldered with Cu-Ni alloy/Sn composite solder for 60 min.

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“…Several types of Sn-based Pb-free solders, such as Sn-Ag, Sn-Cu, Sn-Zn, Sn-Bi, Sn-In, and Sn-Ag-Cu have been developed to replace the conventional Sn-Pb solder alloys [7][8][9]. In response to this, Sn-Cu lead-free solder has attracted wide attention because of its excellent and comprehensive performance, low cost, and widespread use in electronic packaging.…”

Section: Introductionmentioning

confidence: 99%

Effect of Electromigration and Thermal Ageing on the Tin Whiskers’ Formation in Thin Sn–0.7Cu–0.05Ga Lead (Pb)-Free Solder Joints

et al. 2021

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The investigation on tin (Sn) whiskers formation has been widely applied in the field of lead-free electronic packaging. This is due to the fact that use of the Sn–Pb finishes has converted to Pb-free finishes in the electronic industry. Sn whiskers can grow long enough to cause a short circuit, which affects electronic devices’ reliability. This study investigates Sn whiskers’ formation in the thin Sn–0.7Cu–0.05Ga Pb-free solder under the influence of electromigration and thermal ageing for surface finish applications. The samples were stored in ambient conditions for 1000 h before being exposed to electromigration and thermal ageing to study the corresponding whiskers’ growth. A scanning electron microscope (SEM) was used to study the Sn whiskers’ microstructure, while an optical microscope (OM) was utilized to investigate the IMC layers in the samples. The results show that the addition of 0.05 wt.% gallium (Ga) decreased the Sn whisker’s length and growth density while simultaneously refining the IMC layers. Synchrotron micro-XRF (µ-XRF) shows the existence and distribution of Ga addition in both electromigration and thermal ageing samples. The shear test was used to determine the solder alloys’ mechanical properties. As a result, the addition of Ga to the Sn–0.7Cu solder improved the fracture morphology of solder joints. In conclusion, Ga’s addition resulted in decreasing Sn whisker formation and refining of the IMCs while also increasing the shear strength of the Sn–0.7Cu solder by ~14%.

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Influence of Ni on the refinement and twinning of primary Cu6Sn5 in Sn-0.7Cu-0.05Ni

Cited by 28 publications

References 52 publications

Effects of Multiple Reflow on the Formation of Primary Crystals in Sn-3.5Ag and Solder Joint Strength: Experimental and Finite Element Analysis

Effects of Multiple Reflow on the Formation of Primary Crystals in Sn-3.5Ag and Solder Joint Strength: Experimental and Finite Element Analysis

Microstructure and mechanical properties of Cu joints soldered with a Sn-based composite solder, reinforced by metal foam

Effect of Electromigration and Thermal Ageing on the Tin Whiskers’ Formation in Thin Sn–0.7Cu–0.05Ga Lead (Pb)-Free Solder Joints

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