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Microstructural and micromechanical characteristics of tin-based solders under self-propagating exothermic reaction heating

journal contribution
posted on 22.01.2021, 15:20 authored by Zheng Zhou, Anna Zhang, Xu Guan, Hui Liu, Changqing LiuChangqing Liu, Fengshun Wu
In this study, a rapid solder melting process has been examined through a self-propagating exothermic reaction using Al/Ni nanofoil as a localized heat source. Four kinds of tin-based solder preforms were partly melted under this process, and the thicknesses of the fusion zone in solder preforms around the Al/Ni nanofoil were experimentally analyzed. The microstructure and morphology of the fusion zone in different kinds of solder preforms were studied by metallographic analysis. In Sn42Bi58 solder, the mean grain size of Bi-rich phases in the fusion zone was finer than the original structure, and decreased from ~ 2.7 μm to ~ 0.8 μm away from the Al/Ni nanofoil. Similar trends of mean size of grains in the fusion zone were also found in the Sn, Sn-3 wt.%Ag-0.5 wt.%Cu(SAC), and SnPb solder preforms. The widths of the fusion zone in the Sn, SAC, SnPb, and SnBi solder preforms were 150 μm, 173 μm, 188 μm, and 233 μm, respectively. In addition, the nano-hardness and distribution in the fusion zones were evaluated. The results show that the value of nanohardness increased along with the decrease of distance from Al/Ni nanofoil. The average hardness and the lower and upper bounds of Sn, SnPb, SAC, and SnBi solder in the fusion zone are 0.260 (−0.045, +0.039) GPa, 0.246 (−0.059, +0.114) GPa, 0.260 (−0.014, +0.070) GPa, and 0.404 (−0.072, +0.134) GPa, respectively. The statistical significance of solder hardness is related to its alloy component, element content, and microstructure.

Funding

Underpinning Power Electronics 2017: Heterogeneous Integration

Engineering and Physical Sciences Research Council

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Quasi-ambient bonding to enable cost-effective high temperature Pb-free solder interconnects

Engineering and Physical Sciences Research Council

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National Natural Science Foundation of China (NSFC No. 61574068, NSFC No. 61261160498)

China Association for Science and Technology (No. 2018CASTQNJL55)

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

Journal of Electronic Materials

Volume

49

Issue

10

Pages

6214 - 6222

Publisher

Springer

Version

VoR (Version of Record)

Rights holder

© The Minerals, Metals & Materials Society

Publisher statement

This is a post-peer-review, pre-copyedit version of an article published in Journal of Electronic Materials. The final authenticated version is available online at: https://doi.org/10.1007/s11664-020-08363-9.

Acceptance date

28/07/2020

Publication date

2020-08-13

Copyright date

2020

ISSN

0361-5235

eISSN

1543-186X

Language

en

Depositor

Prof Changqing Liu. Deposit date: 20 January 2021