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The study on reliability of Ni-coated graphene doped SAC305 lead-free composite solders under high current-density stressing

Guang Chen (School of Mechanical and Energy Engineering, Zhejiang University, Ningbo Institute of Technology, Ningbo, China)
Jiqiang Li (School of Mechanical and Energy Engineering, Zhejiang University, Ningbo Institute of Technology, Ningbo, China)
Xinwen Kuang (Zhejiang Huashuo Technology Co., LTD, Ningbo, China)
Yaofeng Wu (School of Mechanical and Energy Engineering, Zhejiang University, Ningbo Institute of Technology, Ningbo, China)
Fengshun Wu (State Key Laboratory of Materials Processing and Die and Mould Technology, Huazhong University of Science and Technology, Dalian, China)

Soldering & Surface Mount Technology

ISSN: 0954-0911

Article publication date: 25 June 2019

Issue publication date: 21 August 2019

Abstract

Purpose

The purpose of this paper is to investigate the effect of nickel-plated graphene (Ni-GNS) on the microstructure and mechanical properties of 96.5Sn3Ag0.5Cu (SAC305) lead-free solder joints before and after an electro-migration (EM) experiment.

Design/methodology/approach

In this paper, SAC305 solder alloy doped with 0.1 Wt.% Ni-GNS was prepared via the powder metallurgy method. A U-shaped sample structure was also designed and prepared to conduct an EM experiment. The EM experiment was carried out with a current density of 1.5 × 104 A/cm2. The microstructural and mechanical evolutions of both solder joints under EM stressing were comparatively studied using SEM and nanoindentation.

Findings

The experimental results showed that for the SAC305 solder, the interfacial intermetallic compounds (IMC) formulated a protrusion with an average height of 0.42 µm at the anode after 360 h of EM stressing; however, despite this, the surface of the composite solder joint was relatively smooth. During the stressing period, the interfacial IMC on the anode side of the plain SAC305 solder showed a continuous increasing trend, while the IMC at the cathode presented a decreasing trend for its thickness as the stressing time increased; after 360 h of stressing, some cracks and voids had formed on the cathode side. For the SAC305/ Ni-GNS composite solder, a continuous increase in the thickness of the interfacial IMC was found on both the anode and cathode side; the growth rate of the interfacial IMC at the anode was higher than that at the cathode. The nanoindentation results showed that the hardness of the SAC305 solder joint presented a gradient distribution after EM stressing, while the hardness data showed a relatively homogeneous distribution in the SAC305/ Ni-GNS solder joint.

Originality/value

The experimental results showed that the Ni-GNS reinforcement could effectively mitigate the EM behavior in solder joints under high current stressing. Specifically, the Ni particles that plated the graphene sheets can work as a fixing agent to suppress the diffusion and migration of Sn and Cu atoms by forming Sn-Cu-Ni IMC. In addition, the nanoidentation results also indicated that the addition of the Ni-GNS reinforcement was very helpful in maintaining the mechanical stability of the solder joint. These findings have provided a theoretical and experimental basis for the practical application of this novel composite solder with high current densities.

Keywords

Acknowledgements

This work was supported by the National Nature Science Foundation of China (Grant NO. 61804135) and the Natural Science Foundation of Zhejiang Province of China (Grant NO. LQ17E050004). The authors would also like to thank the Analytical and Testing Centre at Zhejiang Huashuo Technology co., LTD for their analytical and testing services.

Citation

Chen, G., Li, J., Kuang, X., Wu, Y. and Wu, F. (2019), "The study on reliability of Ni-coated graphene doped SAC305 lead-free composite solders under high current-density stressing", Soldering & Surface Mount Technology, Vol. 31 No. 4, pp. 261-270. https://doi.org/10.1108/SSMT-11-2018-0043

Publisher

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Emerald Publishing Limited

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