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Microstructure evolution and shear strength of full Cu3Sn- microporous copper composite joint by thermo-compression bonding

F Sun (The School of Material Science and Engineering, Harbin University of Science and Technology, Harbin, Heilongjiang, China)
Zhen Pan (The School of Material Science and Engineering, Harbin University of Science and Technology, Harbin, Heilongjiang, China)
Yang Liu (The School of Material Science and Engineering, Harbin University of Science and Technology, Harbin, Heilongjiang, China)
Xiang Li (The School of Material Science and Engineering, Harbin University of Science and Technology, Harbin, Heilongjiang, China)
Haoyu Liu (The School of Material Science and Engineering, Harbin University of Science and Technology, Harbin, Heilongjiang, China)
Wenpeng Li (The School of Material Science and Engineering, Harbin University of Science and Technology, Harbin, Heilongjiang, China)

Soldering & Surface Mount Technology

ISSN: 0954-0911

Article publication date: 14 May 2021

Issue publication date: 19 October 2021

206

Abstract

Purpose

The purpose of this paper is to quickly manufacture full Cu3Sn-microporous copper composite joints for high-temperature power electronics applications and study the microstructure evolution and the shear strength of Cu3Sn at different bonding times.

Design/methodology/approach

In this paper, a novel structure of Cu/composite solder sheet/Cu was designed. The composite solder sheet was made of microporous copper filled with Sn. The composite joint was bonded by thermo-compression bonding under pressure of 0.6 MPa at 300°C. The microstructure evolution and the growth behavior of Cu3Sn at different bonding times were observed by electron microscope and metallographic microscope. The shear strength of the joint was measured by shear machine.

Findings

At initial bonding stage the copper atoms in the substrate and the copper atoms in the microporous copper dissolved into the liquid Sn. Then the scallop-liked Cu6Sn5 phases formed at the interface of liquid Sn/microporous copper and liquid Sn/Cu substrates. During the liquid Sn changing to Cu6Sn5 phases, Cu3Sn phases formed and grew at the interface of Cu6Sn5/Cu substrates and Cu6Sn5/microporous copper. After that the Cu3Sn phases continued to grow and the Cu3Sn-microporous copper composite joint with a thickness of 100 µm was successfully obtained. The growth rule of Cu3Sn was parabolic growth. The shear strength of the composite joints was about 155 MPa.

Originality/value

This paper presents a novel full Cu3Sn-microporous copper composite joint with high shear strength for high-temperature applications based on transient liquid phase bonding. The microstructure evolution and the growth behavior of Cu3Sn in the composite joints were studied. The shear strength and the fracture mechanism of the composite joints were studied.

Keywords

Acknowledgements

The work described in the paper was partially supported by the National High Technology Research and Development Program of China (863 Program) (No. 2015AA033304) and partially supported by the National Natural Science Foundation of China (No. 51174069).

Citation

Sun, F., Pan, Z., Liu, Y., Li, X., Liu, H. and Li, W. (2021), "Microstructure evolution and shear strength of full Cu3Sn- microporous copper composite joint by thermo-compression bonding", Soldering & Surface Mount Technology, Vol. 33 No. 5, pp. 274-280. https://doi.org/10.1108/SSMT-10-2020-0047

Publisher

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Emerald Publishing Limited

Copyright © 2021, Emerald Publishing Limited

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