Microstructure evolution, IMC growth, and microhardness of Cu, Ni, Ag-microalloyed Sn-5Sb/Cu solder joints under isothermal aging

Meiling Xin; Xiuqi Wang; Fenglian Sun

doi:10.1007/s10854-022-09210-9

Microstructure evolution, IMC growth, and microhardness of Cu, Ni, Ag-microalloyed Sn-5Sb/Cu solder joints under isothermal aging

J Mater Sci Mater Electron. 2022;33(33):25025-25040. doi: 10.1007/s10854-022-09210-9. Epub 2022 Oct 5.

Authors

Meiling Xin¹, Xiuqi Wang^{1

2}, Fenglian Sun²

Affiliations

¹ State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang, 110819 People's Republic of China.
² School of Materials Science and Chemical Engineering, Harbin University of Science and Technology, Harbin, 150040 People's Republic of China.

Abstract

In this work, various Cu, Ni, Ag-microalloyed Sn-5Sb/Cu joints, ordinary Sn-5Sb/Cu joints, and low-melting-point Sn-3Ag-0.5Cu (SAC305)/Cu (used for comparison) were prepared, focusing on the influence of Cu, Ni, and Ag on the microstructure evolution, interfacial IMC growth, and microhardness of Sn-5Sb/Cu joint under long-time isothermal aging process. Results showed that the microstructure of microalloyed joints consisted of β-Sn matrix, SbSn, and (Cu, Ni)₆Sn₅ and Ag₃Sn compounds. (Cu, Ni)₆Sn₅ compounds generated a coarsening effect in the aging microalloyed joints, yet its coarsening speed is significantly lower than the ordinary Sn-5Sb/Cu. Meanwhile, the total IMC layer thickness increased with the rising aging time. A single fine dendritic (Cu, Ni)₆Sn₅ IMC at the interface of microalloyed joint was observed and evolved into a larger scallop or layer-like duplex IMCs ((Cu, Ni)₆Sn₅ + Cu₃Sn) after the aging. Considering the combined effect of Cu, Ni, and Ag, the microalloyed joints exhibited the improved microstructure relative to ordinary counterparts and low-melting-point SAC305 materials, significantly inhibiting the interfacial IMC growth, especially Cu₃Sn. The Cu₃Sn IMC thickness and diffusion coefficient in the Sn-5Sb-0.5Cu-0.1Ni-0.5Ag/Cu joint were 0.71-2.81 μm and 0.96 × 10^-6 μm·s^-2, respectively. Besides, the precipitation strengthening mechanism triggered by the microalloyed elements was extremely obvious and the soldering and aging joints revealed superior microhardness values of 20-35 HV. This could effectively improve the application range of Sn-5Sb-based materials in higher-temperature package conditions such as third-generation semiconductors.

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