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Ultrasonically enhanced flux-less bonding with Zn-5Al alloy under ambient condition for high-temperature electronics interconnects

journal contribution
posted on 23.11.2021, 14:34 by Canyu LiuCanyu Liu, Allan Liu, Yutai Su, Yi ChenYi Chen, Zhaoxia ZhouZhaoxia Zhou, Changqing LiuChangqing Liu
Zn-5Al eutectic alloy is a promising Pb-free solder suitable for high-temperature electronics packaging. However, the soldering with Zn-5Al alloy is undermined by its poor oxidation resistance and wettability in ambient atmosphere, which also demands significant time to complete if transient liquid phase soldering (TLPS) is required. In this work, the TLPS assisted by ultrasonic vibration (USV) under ambient condition without flux has been performed to enhance and accelerate interfacial reactions between Zn-5Al and Cu or Ni substrate. It has been found that the resultant full intermetallic compounds (IMCs) joints with uniform microstructure can be formed within 1 min and 3 min on Cu and Ni substrate, respectively, without flux or protective inert gases. The IMCs resulted from the interfacial reactions have been identified after the completion of TLPS process. For the ultrasonic-assisted TLPS (U-TLPS) of Zn-5Al onto Cu substrate, the joints consist of three IMC layers, CuZn, Cu5Zn8, and CuZn with the residual oxide fragments remained at the central line inside of IMC Cu5Zn8, where Al is rich likely due to the segregation of element Al during the TLPS process. For the U-TLPS of Zn-5Al onto Ni substrate, three IMC layers, Ni5Zn21, NiAl and Ni5Zn21 IMC were also observed, with the porous Ni5Zn21 IMC layers present in adjacent to the Ni substrate. Both residual oxide fragments in the Zn-5Al/Cu joints and porous Ni5Zn21 IMC in the Zn-5Al/Ni joints could potentially deteriorate mechanical integrity of the joints, which is yet to be understood.

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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China Scholarship Council (CSC) (Reference No. 201806220073)

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

Journal of Manufacturing Processes

Volume

73

Pages

139 - 148

Publisher

Elsevier

Version

AM (Accepted Manuscript)

Rights holder

© 2021 The Society of Manufacturing Engineers

Publisher statement

This paper was accepted for publication in the journal Journal of Manufacturing Processes and the definitive published version is available at https://doi.org/10.1016/j.jmapro.2021.10.065

Acceptance date

31/10/2021

Publication date

2021-11-12

Copyright date

2022

ISSN

1526-6125

Language

en

Depositor

Prof Changqing Liu. Deposit date: 22 November 2021