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Title: Interfacial reaction and microstructural evolution between Au-Ge solder and electroless Ni-W-P metallization in high temperature electronics interconnects
Authors: Liu, Li
Cui, Jinzi
Wang, Jing
Zhou, Zhaoxia
Johnson, R. Wayne
Liu, Changqing
Issue Date: 2017
Publisher: © IEEE
Citation: LIU, L. ... et al., 2017. Interfacial reaction and microstructural evolution between Au-Ge solder and electroless Ni-W-P metallization in high temperature electronics interconnects. Presented at the IEEE 67th Electronic Components and Technology Conference (ECTC), Orlando, FL, USA, 30 May-2 June, pp. 417 - 422.
Abstract: © 2017 IEEE. The elevated working temperature of high temperature electronics can inevitably cause potential excessive growth of interfacial intermetallic compounds (IMCs), which can significantly deteriorate the mechanical integrity of electronic devices. Therefore, a robust diffusion barrier that can operate reliably under elevated temperature is highly demanded to retard the interfacial reaction between solder and substrate. In this work, a ternary Ni-W-P alloy was deposited through electroless plating and applied as an Under Bump Metalisation (UBM) to Au-Ge solder joints. The interfacial reaction in Au-Ge/Ni-W-P solder joints after reflow and prolonged ageing durations was investigated. We found NiGe and Ni5Ge3 layers formed after reflow, however only NiGe was observed after 1000h aging at 300°C. The thickness of NiGe increases linearly with the square root of ageing time up to 1500h, indicating that the growth mechanism of NiGe is diffusion-control process when Ge atoms are sufficient. After ageing for 2000h, although Ge atoms from Au-Ge solder was fully consumed, the Ni-W-P coating remained stable and exhibited excellent diffusion barrier property. During various ageing durations, the top-view morphology of NiGe IMC grains changed from pyramid-like and polygon-like shape at as-built stage to granulate-like (up to 1500h), and finally a polygon-like shape (after 2000h).
Description: © 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Sponsor: The authors would like to acknowledge the research grant funded through Centre of Power Electronics (CPE) of EPSRC via Nottingham University as well as FP7 Marie Curie IRSES Project, M6 (Grant No. PIRSES-GA-2010-269113).
Version: Accepted for publication
DOI: 10.1109/ECTC.2017.61
URI: https://dspace.lboro.ac.uk/2134/36626
Publisher Link: https://doi.org/10.1109/ECTC.2017.61
ISBN: 9781509043323
ISSN: 0569-5503
Appears in Collections:Conference Papers and Presentations (Materials)
Conference Papers and Presentations (Mechanical, Electrical and Manufacturing Engineering)

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