To simulate the growth of Ni 3Sn 4 phase layers in Sn-based solder joints with Ni substrates during solid-state aging, Sn/(Cu 1-x Ni x ) 6Sn 5/Ni and Sn/Ni diffusion couples were aged isothermally at 180°C and 200°C, and the growth kinetics of the (Ni,Cu) 3Sn 4 and Ni 3Sn 4 layers in the respective couples were monitored during the isothermal aging. Once the (Ni,Cu) 3Sn 4 layer was formed at the (Cu,Ni) 6Sn 5/Ni interface, it grew unexpectedly fast with concurrent growth of voids formed in the Sn layer during prolonged aging at both temperatures. The results obtained from the various types of diffusion couples revealed that the voids formed in the Sn layer were Kirkendall voids, due to the (Ni,Cu) 3Sn 4 layer growing predominantly at the (Ni,Cu) 3Sn 4/Ni interface by fast diffusion of Sn across the (Ni,Cu) 3Sn 4 layer. It is proposed that the accelerated growth of the (Ni,Cu) 3Sn 4 and Ni 3Sn 4 layers after the formation of voids in the Sn layer is due to the relaxation of vacancy oversaturation and the enhanced annihilation rate of incoming vacancies in the presence of the voids in the Sn layer.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) Grant (No. 2010-0014480) funded by the Korea government (MEST). J.C. acknowledges the support of the Gangneung-Wonju National University during his stay at Korea University during 2010–2011.
- Kirkendall void
- Ni Sn
- Solder/Ni joint
- interfacial reaction
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry