CALPHAD-guided alloy design of Sn–In based solder joints with multiphase structure and their mechanical properties

X, Luo; Peng, Jubo; Zhang, Wei-Bin; Wang, Shuai; Cai, Shanshan; Wang, Xiaojing

doi:10.1016/j.msea.2022.144284

Cited by 18 publications

(6 citation statements)

References 23 publications

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“…In the development of lead-free solders, Bi, In, and Zn were found to be the most feasible alloying elements for Sn, effectively lowering the melting point of Sn [14], [22], [23], [24], [25]. Nevertheless, it has been found that Sn-Zn solders exhibit poor wettability and corrosion resistance [22], [26], [27], [28], while Sn-Bi solders suffer from low wettability and brittleness due to the inherent nature of bismuth [14], [29], [30], [31]. Furthermore, Cu-Sn-Bi SLID bonding fails to achieve fully formed intermetallic compounds (IMCs) interconnects, even Fahimeh Emadi, Vesa Vuorinen, Shenyi Liu, and Mervi Paulasto-Kröckel are with the Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, PO Box 13340, FI-00076 Aalto, Finland (e-mail: Fahimeh.emadi@alto.fi; vesa.vuorinen@aalto.fi; shenyi.liu@aalto.fi; mervi.paulasto@aalto.fi).…”

Section: Introductionmentioning

confidence: 99%

Novel low-temperature interconnects for 2.5/3D MEMS integration: demonstration and reliability

Emadi,

Vuorinen,

Liu

et al. 2024

Preprint

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In response to the evolving demands of microelectromechanical system (MEMS) integration, aiming to achieve high-performance electronic products, innovative interconnect solutions are becoming essential. The interconnects must possess key features, including the capability for miniaturization, low processing temperatures, and the ability to maintain a stable microstructure with optimized electrical, mechanical, and thermomechanical properties. To meet these demands, this study designed a novel Cu-Sn-based solid-liquid interdiffusion (SLID) interconnect. The study involved the implementation of a metallization stack, incorporating Co as a layer to interact with low-temperature Cu-Sn-In SLID and form intermetallic compounds (IMCs). Since Cu6(Sn,In)5 forms at a lower bonding temperature than other phases commonly observed in the Cu-Sn-In system, the study aimed to develop interconnects comprising a stable single-phase (Cu,Co)6(Sn,In)5. Bonding conditions were established for the Cu-Sn-In/Co system and the Cu-Sn/Co system as a reference. Thorough assessments of their thermomechanical reliability were conducted through hightemperature storage (HTS), thermal shock (TS), and tensile tests. The Cu-Sn-In/Co system emerged as a reliable low-temperature solution with the following key attributes: 1) a reduced bonding temperature compared to the Cu-Sn SLID interconnects, 2) the absence of the Cu3Sn phase and resulting void-free interconnects, and 3) high thermomechanical reliability, particularly following thermal annealing after bonding.

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Section: Introductionmentioning

confidence: 99%

Novel low-temperature interconnects for 2.5/3D MEMS integration: demonstration and reliability

Emadi,

Vuorinen,

Liu

et al. 2024

Preprint

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“…In addition, the requirement for low-temperature welding promotes the widespread application of low melting point SnBi and SnIn alloys. Composition difference results in different types of oxides on powder surface, and the phase composition inside the powders, such as SAC (β-Sn matrix + Ag3Sn + Cu6Sn5 intermetallic compound particles) [4], SnBi alloys (Sn-rich + Bi-rich phases) [5], SnIn alloys (In3Sn + InSn4 phase) [6] etc. Taking Sn58Bi as an example, due to the significant difference in standard electrode potential between Bi (0.307 V) and Sn (-0.137 V), the corrosion resistance of Sn58Bi alloys during storage is relatively poor [7].…”

Section: Introductionmentioning

confidence: 99%

“…The differences in the manufacturing processes related to the corrosion behavior of active substances in metal powder alloys and fluxes. Most previous research has focused on alloy melting characteristics, solderability, their microstructures evolution and associated mechanical properties as well as their reliability [6,8,9]. However, research on the interaction between solder alloys surfaces and activators in flux is lacking [10].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical noise analysis of corrosion sensitivity of Pb-free solders in 5 wt% citric acid solution

Li,

Cai,

Wang

et al. 2024

Adv Compos Hybrid Mater

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The corrosion behavior of pure Sn, Sn2Ag, Sn42In and Sn58Bi alloys in 5 wt.% citric acid solutions has been investigated using electrochemical noise analysis combined with potentiodynamic polarization, electrochemical impedance spectroscopy tests and etching morphology observation. The results indicated that Sn58Bi has the lowest corrosion rate, followed by Sn2Ag, Sn42In, and Sn. The corrosion evolution of the four alloys mainly consists of two stages as follow：for pure Sn, the first stage is local corrosion (corrosion pits growth) stage and the second stage is uniform corrosion with preferential dissolution of some grains on the sample surface. In contrast, for dual phase alloys, Sn2Ag, Sn42In, and Sn58Bi alloys, all preferentially underwent selective phase corrosion in the first stage, followed by the growth of uniform corrosion and selective phase corrosion in the second stage. The corrosion incubation rates for the four Sn-based alloys: Sn42In > Sn > Sn2Ag > Sn58Bi for both uniform corrosion and local corrosion. While the probability of corrosion growth in sequence was: Sn > Sn58Bi > Sn42In > Sn2Ag (uniform corrosion), Sn58Bi > Sn > Sn42In > Sn2Ag (local corrosion). In this work, the corrosion behaviors were consistent with the observed corrosion morphology, which provided guidance for understanding the interaction between solder alloys surfaces and acid in flux and further selecting organic acid activators compatible with new solder alloys.

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“…Thus, introducing solid solution strengthening into precipitation hardening tin based alloys can effectively improve the high temperature resistance of the β-Sn matrix [20,21]. For β-Sn matrix, solid solution strengthening can be achieved by Bi, Sb, In without obvious oxidation [4,15,22,23].…”

Section: Introductionmentioning

confidence: 99%

“…Among them, Bi and In are used as main alloy elements (not micro alloy elements) to reduce the melting point, while the addition of Sb could increase the melting point [22,24].…”

Section: Introductionmentioning

confidence: 99%

Microstructures and shear properties of Sb and In strengthened Sn5Bi/Cu joints

Zhang,

Zhao,

Wang

et al. 2023

Preprint

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The effects of x(Sb/In) (x = 1, 2, 3 wt.%) added to Sn5Bi solder alloy on the melting properties, microstructures and the shear behavior of solder/Cu joints were investigated combined with the corresponding phase diagram. It is found that the addition of Sb reduces the melting range and supercooling with the increase of Sb content caused by SnSb formation, while the In addition can reduce the melting point resulted by In solid solution. Both Sn5BixIn/Cu and Sn5BixSb/Cu are mainly composed of β-Sn and two types precipitates, i.e. Bi particles and Cu6Sn5 compound. The difference lies in that In doping only can dissolve into β-Sn and Cu6Sn5 while Sb doping mainly form tiny SnSb. Increase In content also inhibit precipitation of Bi particles and reduce the phase fraction Cu6(SnIn)5, resulting in that precipitation strengthening becomes weaker and solid solution strengthening becomes stronger. In contrast, the phase fraction of Bi particles and Cu6Sn5 increases with increasing Sb content, leading to that precipitation strengthening becomes stronger. These strengthening mechanism causes that their ultimate shear force monotonically increases with increasing Sb and In content, and the strengthening effect of the Sb element is better. Sb and In addition also can improve the ductility of Sn5Bi/Cu solder joints and both 2 wt.% In/Sb addition present the best shear fracture work. Thus, the optimal mechanical property was achieved by 2 wt.% Sb addition.

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CALPHAD-guided alloy design of Sn–In based solder joints with multiphase structure and their mechanical properties

Cited by 18 publications

References 23 publications

Novel low-temperature interconnects for 2.5/3D MEMS integration: demonstration and reliability

Novel low-temperature interconnects for 2.5/3D MEMS integration: demonstration and reliability

Electrochemical noise analysis of corrosion sensitivity of Pb-free solders in 5 wt% citric acid solution

Microstructures and shear properties of Sb and In strengthened Sn5Bi/Cu joints

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