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Co interface during reflows
Materials Letters 254 (2019) 69–72
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Thermal stability of intermetallic compounds at Sn-0.7Cu-10Bi-xNi/Co interface during reflows He Gao a,b,c, Fuxiang Wei a,b,c,⇑, Caixia Lin a, Tie Shu a, Yanwei Sui a,b, Jiqiu Qi a, Xuping Zhang a a
School of Materials Science & Engineering, China University of Mining & Technology, Xuzhou 221116, PR China The Jiangsu Province Engineering Laboratory of High Efficient Energy Storage Technology & Equipments under, China University of Mining & Technology, Xuzhou, PR China c The Xuzhou City Key Laboratory of High Efficient Energy Storage Technology & Equipments under, China University of Mining & Technology, Xuzhou, PR China b
a r t i c l e
i n f o
Article history: Received 1 July 2019 Received in revised form 8 July 2019 Accepted 10 July 2019 Available online 10 July 2019 Keywords: Intermetallic alloys and compounds Thermal stability Ni enrichment Interfaces Microstructure
a b s t r a c t In this paper, thermal stability of Sn-0.7Cu-10B-xNi/Co (SCB-xNi/Co, x = 0.05, 0.10 and 0.15, in wt.%) interface during multiple reflows was investigated. Both (Ni,Co)Sn3 and (Cu,Ni)6Sn5 phases were formed at the SCB-xNi/Co interface after the initial reflow. With the increase of reflow number, the thermal stability of intermetallic compounds (IMCs) layer at high temperature was significantly different. The content of Ni atoms determined the thermal stability of IMCs layer in the interface reaction process. At the IMCs layer at the SCB-0.15Ni/Co interface, Ni atoms were enriched excessively, but they were present in a dispersive distribution at SCB-0.05Ni/Co and SCB-0.10Ni/Co interfaces. Ni atoms occupied sublattice sites of Co atoms in CoSn3 phase, which could improve the high-temperature stability of IMCs layer, so the IMCs layer had the strongest thermal stability at the SCB-0.15Ni/Co interface. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction The I/O operations increase in number exponentially with the miniaturization and densification in the electronic packaging, and these generate a lot of heat in the process of use, which affects the quality of solder joints in the packaging. So service life and failure analysis of electrical and electronic parts are widely concerned [1]. Co and Co-alloys are regarded as a new atomic diffusion barrier layer to replace the tradition Cu substrate due to their good wettability and high Young’s modulus [2,3]. Morphology and thickness of Cu6Sn5 and Cu3Sn produced in the interface reaction process between Cu substrate and Sn-based solder have a great influence on the quality of the solder joint, and they have a negative impact on the packaging quality [4]. Co-Sn compounds formed during the interface reaction between Co/Co-alloys and Sn-based solder can effectively inhibit the diffusion of Cu atoms from the substrate to interface, and they can hinder the growth and evolution of Cu-Sn compounds during service of solder joint [5]. Wang et al. found that the Co-Sn compounds generated in the interface reaction could obviously inhibit the growth of Cu-Sn compounds, and they were a good diffusion barrier layer of Cu atoms [6]. With the promotion of lead-free and green manufacturing in electronic packag⇑ Corresponding author at: School of Materials Science & Engineering, China University of Mining & Technology, Xuzhou 221116, PR China. E-mail address: [email protected] (F. Wei). https://doi.org/10.1016/j.matlet.2019.07.034 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
ing, the traditional Sn-Pb solder had been prohibited. This would usher in a boom period of lead-free solder. Many researchers studied on Sn-Cu, Sn-Ag-Cu, Sn-Zn and other Sn-based lead-free solders [7]. However, one of key problems in the application of lead-free solder is that its higher peak temperature and holding time during soldering occurred with higher melting point than that of Sn-Pb eutectic solder (183 °C). This would further damage electronic components in the soldering process, reduce their service life and increase energy consumption and manufacturing cost [8]. There are a large number of researches on growth behaviors of Co-Sn compounds in the interface reaction. As the temperature is needed in solder joints for electronic components with packaging density and high power, so it is necessary to study the growth evolution rhythm of the Co-Sn compounds under the high temperature. Moreover, failure analysis and life prediction of electronic parts are done to improve the quality of electronic packaging and service life. However, at present, few studies have been conducted on the growth and evolution mechanism of Co-Sn compounds at the high temperature. In this work, the low-temperature Sn-0.7Cu-10Bi-xNi (x = 0.05, 0.10 and 0.15, in wt.%) composite lead-free solders were obtained in previous research [8], and used to investigate the influence of high-temperature interface reaction with different Ni contents on the growth and evolution of Co-Sn compounds under multiple reflows, and to explore the failure mechanism of Co-Sn compounds in high-temperature interface reaction.
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Fig. 1. The morphology of SEM images of SCB-xNi/Co (x = 0.05, 0.10 and 0.15, in wt.%) interface after different reflows. (a1-a4), (b1-b4) and (c1-c4) represent the morphologies of SCB-0.05Ni/Co, SCB-0.10Ni/Co and SCB-0.15Ni/Co interfaces after one, three, five and ten reflows, respectively.
2. Experiment and materials The Co plate used in this experiment had a purity of 99.9%, and the Sn-0.7Cu-10Bi-xNi (x = 0.05, 0.10 and 0.15, in wt.%) lead-free solders prepared in the previous experiment were processed into thin sheets with a diameter of 5 mm and a thickness of 2 mm [8]. Before the soldering experiment, the Co substrate and solder sheets were polished with sandpaper and ultrasonically cleaned in alcohol (C2H5OH), and then dried for late use. In order to obviously observe the growth and evolution rules of Co-Sn compounds at the high temperature, the peak temperature of reflow was 280 °C for 200 s, and the number of reflow cycles (1, 3, 5 and 10) was used as the variable in this experiment. The SCB-xNi/Co samples were cut vertically along the interface. Before the crosssectional morphology of SCB-xNi/Co interface was observed, the interface was first polished with sandpaper and Al2O3 suspension, then etched with 2 vol% HCl + 6 vol% HNO3 + 92 vol% C2H5OH for
about 20 s. The Scanning Electron Microscope (SEM, Quanta 250, FEI, USA) was used to observe the morphology of Co-Sn compounds, the Energy Dispersive X-ray Spectroscope (EDS, Quantax 400-10, Bruker, Germany) was used to determine the corresponding component, and the Electron Probe Micro-Analyzer (EPMA, EPMA-8050G, Shimadzu, Japan) was used to make more accurate and intuitive distribution of elements and composition of the interface compounds. The thickness of the IMCs layer was measured by image J software. 3. Results and discussion Fig. 1(a1, b1 & c1) shows the SEM images of SCB-xNi/Co interface IMCs layer after initial reflow. It is clearly seen that the morphology of all IMCs layers is planar and composed of (Ni,Co)Sn3 phase, and the (Cu,Ni)6Sn5 phase is generated adjacent to IMCs layer in the solder matrix. Fig. 1(a2, b2 & c2) shows the SEM images of
H. Gao et al. / Materials Letters 254 (2019) 69–72
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Fig. 2. EPMA mapping analysis results of SCB-xNi/Co (x = 0.05, 0.10 and 0.15, in wt.%) interface after different reflows. (a & c) represents SCB-0.05Ni/Co after one and ten reflows respectively; (b & d) represents SCB-0.15Ni/Co after three and ten reflows respectively.
SCB-xNi/Co interface IMCs layer after three reflows. When the reflow reaches to three cycles, the SCB-0.05Ni/Co interface IMCs layer is obviously thickened. This is because Co atoms continuously are diffused to the interface and combined with Sn atoms to form the (Ni,Co)Sn3 phase. At the same time, a small number of free IMCs particles appear above the IMCs layer, and the IMCs layer begins to be decomposed. There are a few IMCs particles above the IMCs layer (Fig. 1(a2)). However, the SCB-0.10Ni/Co interface IMCs layer shows obvious decomposition, and produces a large number of free IMCs particles (Fig. 1(b2)). The decomposition of the IMCs is caused by the instability of IMCs and the decrease of Co concentration at the interface during high-temperature interface reaction [2,3,9]. The obvious decomposition also appears at the SCB-0.05Ni/Co interface after five reflows (as shown in Fig. 1 (a3)). The SCB-0.15Ni/Co interface IMCs layer remains relatively stable after five reflows, and its thickness increases slightly. The decomposition does not occur until ten reflows. It is noticed that the growth of IMCs layer was in a discontinuous state at the interface of solder joints (Fig. 1(a3, b4 & c4)), which was caused by the phenomenon of completely or incompletely wetting at the grain boundary during the interfacial reaction [10,11]. Fig. 2 shows the EPMA elemental mapping analysis of the SCB-xNi/Co interface after multiple reflows. It can be seen clearly seen from analysis that the Ni atoms are enriched at SCB-0.15Ni/Co interface IMCs layer (Fig. 2(b)), while at SCB-0.05Ni/Co and SCB-0.10Ni/Co interfaces, Ni atoms are distributed in the solder matrix and IMC layer in a dispersive state. The content and counts of Ni atoms at SCB0.15Ni/Co interface are significantly higher than that of other interfaces (Fig. 2(a &c) and Table S1). Ni atoms occupy sublattice sites of Co atoms in CoSn3 phase (Fig. 3(a)) to form more stable (Ni,Co)Sn3
phase [12,13]. And with the increase of Ni content in (Ni,Co)Sn3 phase, the high-temperature stability of IMCs layer increases, which is why SCB-0.15Ni/Co interface IMCs layer is best stabilized. Fig. 3(b) represents the thickness of IMCs layer after different reflows. It can be clearly seen from the Fig. 3(b) that the SCB0.15Ni/Co interface IMCs layer still keeps a good thermal stability after five reflows. After ten reflows, the free-state IMCs particles on the interface of SCB-0.05Ni/Co and SCB-0.10Ni/Co grow up again under driven by adsorption force. The ICMs layer and square IMCs particles are made up of (Ni,Co)Sn2, and they appear with the decomposition of (Ni,Co)Sn3 in the interface reaction ((Ni,Co) Sn3 ? (Ni,Co)Sn2 + Sn). This coincides with the results in other reports [2,3,14]. 4. Conclusions The interface reaction between the new type low-temperature composite Sn-0.7Cu-10B-xNi/Co solders and Co substrate during different reflows and high-temperature thermal stability of IMCs layer were studied. The results indicate that the Ni content in the IMCs layer affects its thermal stability in the interface reaction. Ni atoms in the IMCs layer occupy in the sublattice sites of Co atoms in CoSn3 phase to form more stable (Ni,Co)Sn3 phase. The Ni atoms in the SCB-0.05Ni/Co and SCB-0.10Ni/Co are distributed in a dispersive state, and the IMCs layer presents a lower Ni content. However, Ni atoms are gathered in the SCB-0.15Ni/Co interface IMCs layer, and reach a higher Ni content in (Ni,Co)Sn3. And increase of Ni content can enhance the thermal stability of (Ni, Co)Sn3 phase, indicating the IMCs layer has better hightemperature thermal stability.
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Declaration of Competing Interest We confirm that there are no known conflicts of interest associated with this publication. Acknowledgements This work was supported by ‘‘the Fundamental Research Funds for the Central Universities” (2019XKQYMS13). We all authors thank Advanced Analysis & Computation Center of China University of Mining & Technology for their support and help in this experimental test. H. Gao, one of the author, would like to extend thanks to Dr. S. Wang and Dr. Z.L. Lu for their guidance on EPMA and SEM analysis and testing. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.07.034. References [1] Z.L. Ma, S.A. Belyakov, K. Sweatman, T. Nishimura, T. Nishimura, C.M. Gourlay, Nat. Commun. 8 (2017) 1916–1925. [2] H. Gao, F. Wei, C. Lin, T. Shu, Y. Sui, J. Qi, X. Zhang, Mater. Lett. 252 (2019) 92– 95. [3] H. Gao, F. Wei, Y. Sui, J. Qi. Mater. Des. 174 (2019) 107794. [4] H.Y. Zhao, J.H. Liu, Z.L. Li, Y.X. Zhao, H.W. Niu, X.G. Song, H.J. Dong, Mater. Lett. 186 (2017) 283–288. [5] Z.L. Ma, C.M. Gourlay, J. Alloys Compd. 706 (2017) 596–608. [6] C.H. Wang, S.E. Huang, C.W. Chiu, J. Alloys Compd. 619 (2015) 474–480. [7] T. Laurila, V. Vuorinen, J.K. Kivilahti, Mater. Sci. Eng. R 37 (2006) 1–60. [8] H. Gao, F. Wei, Y. Sui, J. Qi, Y. He, Q. Meng, J. Mater. Sci. Mater. Electron. 30 (2019) 2186–2191. [9] J.F. Li, S.H. Mannan, M.P. Clode, D.C. Whalley, D.A. Hutt, Acta Mater. 54 (2006) 2907–2922. [10] O.A. Kogtenkova, A.B. Straumal, N.S. Afonikova, A.A. Mazilkin, K.I. Kolesnikova, B.B. Straumal, Phys. Solid State 58 (2016) 742–746. [11] B. Straumal, W. Gust, T. Watanabe, Mater. Sci. Forum 294–296 (1999) 411– 414. [12] C.H. Wang, C.Y. Kuo, Mater. Chem. Phys. 130 (2011) 651–656. [13] K.C. Huang, F.S. Shieu, T.S. Huang, C.T. Lu, C.W. Chen, H.W. Tseng, S.L. Cheng, C. Y. Liu, J. Electron. Mater. 39 (2010) 2403–2411. [14] F. Gao, F. Cheng, H. Nishikawa, T. Takemoto, Mater. Lett. 62 (2008) 2257–2259.
Fig. 3. (a) Schematic diagram of Ni atoms replacement process in interface reaction; (b) The thickness of SCB-xNi/Co (x = 0.05, 0.10 and 0.15, in wt.%) interface IMCs layer after multiple reflows.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Thermal stability of intermetallic compounds at Sn-0.7Cu-10Bi-xNi/Co interface during reflows He Gao a,b,c, Fuxiang Wei a,b,c,⇑, Caixia Lin a, Tie Shu a, Yanwei Sui a,b, Jiqiu Qi a, Xuping Zhang a a
School of Materials Science & Engineering, China University of Mining & Technology, Xuzhou 221116, PR China The Jiangsu Province Engineering Laboratory of High Efficient Energy Storage Technology & Equipments under, China University of Mining & Technology, Xuzhou, PR China c The Xuzhou City Key Laboratory of High Efficient Energy Storage Technology & Equipments under, China University of Mining & Technology, Xuzhou, PR China b
a r t i c l e
i n f o
Article history: Received 1 July 2019 Received in revised form 8 July 2019 Accepted 10 July 2019 Available online 10 July 2019 Keywords: Intermetallic alloys and compounds Thermal stability Ni enrichment Interfaces Microstructure
a b s t r a c t In this paper, thermal stability of Sn-0.7Cu-10B-xNi/Co (SCB-xNi/Co, x = 0.05, 0.10 and 0.15, in wt.%) interface during multiple reflows was investigated. Both (Ni,Co)Sn3 and (Cu,Ni)6Sn5 phases were formed at the SCB-xNi/Co interface after the initial reflow. With the increase of reflow number, the thermal stability of intermetallic compounds (IMCs) layer at high temperature was significantly different. The content of Ni atoms determined the thermal stability of IMCs layer in the interface reaction process. At the IMCs layer at the SCB-0.15Ni/Co interface, Ni atoms were enriched excessively, but they were present in a dispersive distribution at SCB-0.05Ni/Co and SCB-0.10Ni/Co interfaces. Ni atoms occupied sublattice sites of Co atoms in CoSn3 phase, which could improve the high-temperature stability of IMCs layer, so the IMCs layer had the strongest thermal stability at the SCB-0.15Ni/Co interface. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction The I/O operations increase in number exponentially with the miniaturization and densification in the electronic packaging, and these generate a lot of heat in the process of use, which affects the quality of solder joints in the packaging. So service life and failure analysis of electrical and electronic parts are widely concerned [1]. Co and Co-alloys are regarded as a new atomic diffusion barrier layer to replace the tradition Cu substrate due to their good wettability and high Young’s modulus [2,3]. Morphology and thickness of Cu6Sn5 and Cu3Sn produced in the interface reaction process between Cu substrate and Sn-based solder have a great influence on the quality of the solder joint, and they have a negative impact on the packaging quality [4]. Co-Sn compounds formed during the interface reaction between Co/Co-alloys and Sn-based solder can effectively inhibit the diffusion of Cu atoms from the substrate to interface, and they can hinder the growth and evolution of Cu-Sn compounds during service of solder joint [5]. Wang et al. found that the Co-Sn compounds generated in the interface reaction could obviously inhibit the growth of Cu-Sn compounds, and they were a good diffusion barrier layer of Cu atoms [6]. With the promotion of lead-free and green manufacturing in electronic packag⇑ Corresponding author at: School of Materials Science & Engineering, China University of Mining & Technology, Xuzhou 221116, PR China. E-mail address: [email protected] (F. Wei). https://doi.org/10.1016/j.matlet.2019.07.034 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
ing, the traditional Sn-Pb solder had been prohibited. This would usher in a boom period of lead-free solder. Many researchers studied on Sn-Cu, Sn-Ag-Cu, Sn-Zn and other Sn-based lead-free solders [7]. However, one of key problems in the application of lead-free solder is that its higher peak temperature and holding time during soldering occurred with higher melting point than that of Sn-Pb eutectic solder (183 °C). This would further damage electronic components in the soldering process, reduce their service life and increase energy consumption and manufacturing cost [8]. There are a large number of researches on growth behaviors of Co-Sn compounds in the interface reaction. As the temperature is needed in solder joints for electronic components with packaging density and high power, so it is necessary to study the growth evolution rhythm of the Co-Sn compounds under the high temperature. Moreover, failure analysis and life prediction of electronic parts are done to improve the quality of electronic packaging and service life. However, at present, few studies have been conducted on the growth and evolution mechanism of Co-Sn compounds at the high temperature. In this work, the low-temperature Sn-0.7Cu-10Bi-xNi (x = 0.05, 0.10 and 0.15, in wt.%) composite lead-free solders were obtained in previous research [8], and used to investigate the influence of high-temperature interface reaction with different Ni contents on the growth and evolution of Co-Sn compounds under multiple reflows, and to explore the failure mechanism of Co-Sn compounds in high-temperature interface reaction.
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Fig. 1. The morphology of SEM images of SCB-xNi/Co (x = 0.05, 0.10 and 0.15, in wt.%) interface after different reflows. (a1-a4), (b1-b4) and (c1-c4) represent the morphologies of SCB-0.05Ni/Co, SCB-0.10Ni/Co and SCB-0.15Ni/Co interfaces after one, three, five and ten reflows, respectively.
2. Experiment and materials The Co plate used in this experiment had a purity of 99.9%, and the Sn-0.7Cu-10Bi-xNi (x = 0.05, 0.10 and 0.15, in wt.%) lead-free solders prepared in the previous experiment were processed into thin sheets with a diameter of 5 mm and a thickness of 2 mm [8]. Before the soldering experiment, the Co substrate and solder sheets were polished with sandpaper and ultrasonically cleaned in alcohol (C2H5OH), and then dried for late use. In order to obviously observe the growth and evolution rules of Co-Sn compounds at the high temperature, the peak temperature of reflow was 280 °C for 200 s, and the number of reflow cycles (1, 3, 5 and 10) was used as the variable in this experiment. The SCB-xNi/Co samples were cut vertically along the interface. Before the crosssectional morphology of SCB-xNi/Co interface was observed, the interface was first polished with sandpaper and Al2O3 suspension, then etched with 2 vol% HCl + 6 vol% HNO3 + 92 vol% C2H5OH for
about 20 s. The Scanning Electron Microscope (SEM, Quanta 250, FEI, USA) was used to observe the morphology of Co-Sn compounds, the Energy Dispersive X-ray Spectroscope (EDS, Quantax 400-10, Bruker, Germany) was used to determine the corresponding component, and the Electron Probe Micro-Analyzer (EPMA, EPMA-8050G, Shimadzu, Japan) was used to make more accurate and intuitive distribution of elements and composition of the interface compounds. The thickness of the IMCs layer was measured by image J software. 3. Results and discussion Fig. 1(a1, b1 & c1) shows the SEM images of SCB-xNi/Co interface IMCs layer after initial reflow. It is clearly seen that the morphology of all IMCs layers is planar and composed of (Ni,Co)Sn3 phase, and the (Cu,Ni)6Sn5 phase is generated adjacent to IMCs layer in the solder matrix. Fig. 1(a2, b2 & c2) shows the SEM images of
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Fig. 2. EPMA mapping analysis results of SCB-xNi/Co (x = 0.05, 0.10 and 0.15, in wt.%) interface after different reflows. (a & c) represents SCB-0.05Ni/Co after one and ten reflows respectively; (b & d) represents SCB-0.15Ni/Co after three and ten reflows respectively.
SCB-xNi/Co interface IMCs layer after three reflows. When the reflow reaches to three cycles, the SCB-0.05Ni/Co interface IMCs layer is obviously thickened. This is because Co atoms continuously are diffused to the interface and combined with Sn atoms to form the (Ni,Co)Sn3 phase. At the same time, a small number of free IMCs particles appear above the IMCs layer, and the IMCs layer begins to be decomposed. There are a few IMCs particles above the IMCs layer (Fig. 1(a2)). However, the SCB-0.10Ni/Co interface IMCs layer shows obvious decomposition, and produces a large number of free IMCs particles (Fig. 1(b2)). The decomposition of the IMCs is caused by the instability of IMCs and the decrease of Co concentration at the interface during high-temperature interface reaction [2,3,9]. The obvious decomposition also appears at the SCB-0.05Ni/Co interface after five reflows (as shown in Fig. 1 (a3)). The SCB-0.15Ni/Co interface IMCs layer remains relatively stable after five reflows, and its thickness increases slightly. The decomposition does not occur until ten reflows. It is noticed that the growth of IMCs layer was in a discontinuous state at the interface of solder joints (Fig. 1(a3, b4 & c4)), which was caused by the phenomenon of completely or incompletely wetting at the grain boundary during the interfacial reaction [10,11]. Fig. 2 shows the EPMA elemental mapping analysis of the SCB-xNi/Co interface after multiple reflows. It can be seen clearly seen from analysis that the Ni atoms are enriched at SCB-0.15Ni/Co interface IMCs layer (Fig. 2(b)), while at SCB-0.05Ni/Co and SCB-0.10Ni/Co interfaces, Ni atoms are distributed in the solder matrix and IMC layer in a dispersive state. The content and counts of Ni atoms at SCB0.15Ni/Co interface are significantly higher than that of other interfaces (Fig. 2(a &c) and Table S1). Ni atoms occupy sublattice sites of Co atoms in CoSn3 phase (Fig. 3(a)) to form more stable (Ni,Co)Sn3
phase [12,13]. And with the increase of Ni content in (Ni,Co)Sn3 phase, the high-temperature stability of IMCs layer increases, which is why SCB-0.15Ni/Co interface IMCs layer is best stabilized. Fig. 3(b) represents the thickness of IMCs layer after different reflows. It can be clearly seen from the Fig. 3(b) that the SCB0.15Ni/Co interface IMCs layer still keeps a good thermal stability after five reflows. After ten reflows, the free-state IMCs particles on the interface of SCB-0.05Ni/Co and SCB-0.10Ni/Co grow up again under driven by adsorption force. The ICMs layer and square IMCs particles are made up of (Ni,Co)Sn2, and they appear with the decomposition of (Ni,Co)Sn3 in the interface reaction ((Ni,Co) Sn3 ? (Ni,Co)Sn2 + Sn). This coincides with the results in other reports [2,3,14]. 4. Conclusions The interface reaction between the new type low-temperature composite Sn-0.7Cu-10B-xNi/Co solders and Co substrate during different reflows and high-temperature thermal stability of IMCs layer were studied. The results indicate that the Ni content in the IMCs layer affects its thermal stability in the interface reaction. Ni atoms in the IMCs layer occupy in the sublattice sites of Co atoms in CoSn3 phase to form more stable (Ni,Co)Sn3 phase. The Ni atoms in the SCB-0.05Ni/Co and SCB-0.10Ni/Co are distributed in a dispersive state, and the IMCs layer presents a lower Ni content. However, Ni atoms are gathered in the SCB-0.15Ni/Co interface IMCs layer, and reach a higher Ni content in (Ni,Co)Sn3. And increase of Ni content can enhance the thermal stability of (Ni, Co)Sn3 phase, indicating the IMCs layer has better hightemperature thermal stability.
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Declaration of Competing Interest We confirm that there are no known conflicts of interest associated with this publication. Acknowledgements This work was supported by ‘‘the Fundamental Research Funds for the Central Universities” (2019XKQYMS13). We all authors thank Advanced Analysis & Computation Center of China University of Mining & Technology for their support and help in this experimental test. H. Gao, one of the author, would like to extend thanks to Dr. S. Wang and Dr. Z.L. Lu for their guidance on EPMA and SEM analysis and testing. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.07.034. References [1] Z.L. Ma, S.A. Belyakov, K. Sweatman, T. Nishimura, T. Nishimura, C.M. Gourlay, Nat. Commun. 8 (2017) 1916–1925. [2] H. Gao, F. Wei, C. Lin, T. Shu, Y. Sui, J. Qi, X. Zhang, Mater. Lett. 252 (2019) 92– 95. [3] H. Gao, F. Wei, Y. Sui, J. Qi. Mater. Des. 174 (2019) 107794. [4] H.Y. Zhao, J.H. Liu, Z.L. Li, Y.X. Zhao, H.W. Niu, X.G. Song, H.J. Dong, Mater. Lett. 186 (2017) 283–288. [5] Z.L. Ma, C.M. Gourlay, J. Alloys Compd. 706 (2017) 596–608. [6] C.H. Wang, S.E. Huang, C.W. Chiu, J. Alloys Compd. 619 (2015) 474–480. [7] T. Laurila, V. Vuorinen, J.K. Kivilahti, Mater. Sci. Eng. R 37 (2006) 1–60. [8] H. Gao, F. Wei, Y. Sui, J. Qi, Y. He, Q. Meng, J. Mater. Sci. Mater. Electron. 30 (2019) 2186–2191. [9] J.F. Li, S.H. Mannan, M.P. Clode, D.C. Whalley, D.A. Hutt, Acta Mater. 54 (2006) 2907–2922. [10] O.A. Kogtenkova, A.B. Straumal, N.S. Afonikova, A.A. Mazilkin, K.I. Kolesnikova, B.B. Straumal, Phys. Solid State 58 (2016) 742–746. [11] B. Straumal, W. Gust, T. Watanabe, Mater. Sci. Forum 294–296 (1999) 411– 414. [12] C.H. Wang, C.Y. Kuo, Mater. Chem. Phys. 130 (2011) 651–656. [13] K.C. Huang, F.S. Shieu, T.S. Huang, C.T. Lu, C.W. Chen, H.W. Tseng, S.L. Cheng, C. Y. Liu, J. Electron. Mater. 39 (2010) 2403–2411. [14] F. Gao, F. Cheng, H. Nishikawa, T. Takemoto, Mater. Lett. 62 (2008) 2257–2259.
Fig. 3. (a) Schematic diagram of Ni atoms replacement process in interface reaction; (b) The thickness of SCB-xNi/Co (x = 0.05, 0.10 and 0.15, in wt.%) interface IMCs layer after multiple reflows.