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Title: Diffusion barrier property of electroless Ni-W-P coating in high temperature Zn-5Al/Cu solder interconnects
Authors: Liu, Li
Chen, Zhiwen
Zhou, Zhaoxia
Chen, Guang
Wu, Fengshun
Liu, Changqing
Keywords: Zn-5Al solder
Electroless Ni-W-P coating
Diffusion barrier
Interfacial reaction
Kirkendall voids
Issue Date: 2017
Publisher: © Elsevier
Citation: LIU, L. ... et al, 2017. Diffusion barrier property of electroless Ni-W-P coating in high temperature Zn-5Al/Cu solder interconnects. Journal of Alloys and Compounds, 722, pp. 746–752.
Abstract: The operating temperature of high-temperature electronics can significantly promote the growth of intermetallic compounds (IMCs) at solder/substrate interfaces, particularly for low-cost Zn-based solders because of the rapid rate of reaction of Zn with Cu. Thus, a reliable and robust diffusion barrier is indispensable for suppressing the reactions between solder and substrate. In this work, a ternary Ni-W-P alloy was prepared via electroless plating. Its diffusion barrier property was evaluated by comparing the microstructures of IMC layers in Zn-5Al/Ni-W-P/Cu and Zn-5Al/Cu interconnects after liquid-solid reaction for prolonged durations. When the reaction lasted for 30 min, the thickness of the Al3Ni2 produced in the Zn-5Al/Ni-W-P/Cu solder interconnects was only 2.15 μm, whereas the thickness of the interfacial layer of Cu-Zn IMCs (CuZn4, Cu5Zn8 and CuZn) at the Zn-5Al/Cu interface was 94 μm. Because of the unbalanced growth of the IMCs in the Zn-5Al/Cu interconnects, notable numbers of Kirkendall voids were identified at the CuZn4/Cu5Zn8, Cu5Zn8/CuZn and CuZn/Cu interfaces after prolonged liquid-solid reaction. By contrast, the Al3Ni2 layer in the Zn-5Al/Ni-W-P/Cu solder joints remained intact, showing the potential to effectively enhance the mechanical reliability of electronic devices.
Description: This paper was accepted for publication in the journal Journal of Alloys and Compounds and the definitive published version is available at https://doi.org/10.1016/j.jallcom.2017.06.122
Sponsor: This research was supported by a Marie Curie International Research Staff Exchange Scheme Project within the 7th European Community Framework Programme, No. PIRSES-GA-2010-269113, entitled “Micro-Multi-Material Manufacture to Enable Multifunctional Miniaturised Devices (M6)”, as well as an EPSRC-CPB Funding (GRANT NO. FS14). The authors also acknowledge the research funding by the National Nature Science Foundation of China (NSFC GRANT NO. 61261160498).
Version: Accepted for publication
DOI: 10.1016/j.jallcom.2017.06.122
URI: https://dspace.lboro.ac.uk/2134/25511
Publisher Link: https://doi.org/10.1016/j.jallcom.2017.06.122
ISSN: 1873-4669
Appears in Collections:Published Articles (Mechanical, Electrical and Manufacturing Engineering)

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