Growth Behavior of Meta-Stable ${\rm NiSn}_{3}$ Intermetallic Compound and Its Potential Influence on the Reliability of Electronic Components

The morphology, texture evolution and growth behavior of the meta-stable NiSn₃ intermetallic compound (IMC) in Sn electrodeposits over Ni were investigated. It was found that at lower storage temperatures (<; 100^°C), the plate-like NiSn₃ is the dominant IMC phase in the Sn layers. Upon raising the temperature, a competition between the initiations of NiSn₃ and Ni₃Sn₄ phases was observed as identified by energy dispersive X-ray. The crystal structure of NiSn₃ was determined by the powder diffraction pattern. The investigations revealed that the growth rate of NiSn₃ in terms of the penetration depth from the Sn/Ni interface to the Sn surface follows the square-root power law, implying a diffusion controlled phase growth. The diffusion coefficients of the NiSn₃ phase growth were determined at different temperatures (25^°C, 50^°C, and 75^°C), which are significantly higher than that reported for Ni₃Sn₄ under the same temperatures. The activation energy for the growth of NiSn₃ obtained is 39.90 kJ/mol. Hardness and Young´s modulus of NiSn₃ were determined by means of nanoindentation. This paper discusses the potential influences of the NiSn₃ phase growth on the reliability of electronic components containing Ni-Sn diffusion couple.