Study on the Kinetics of Ni3Sn4 Growth and Isothermal Solidification in Ni-Sn TLPS Bonding Process

In this work, the kinetics of Ni3Sn4 growth and the isothermal solidification kinetics in Ni-Sn transient liquid phase sintering bonding process (TLPS bonding) were systematically investigated by a physical simulation method to sinter the Ni-Sn mixed powder compacts. It was confirmed that during the Ni-Sn TLPS bonding process, only Ni3Sn4 formed around the Ni particles when liquid Sn remained in the samples; only if the liquid Sn was consumed did Ni3Sn began to form from Ni3Sn4. A kinetic unit cell model in three dimensions and corresponding kinetic equations were established to describe the Ni3Sn4 growth during the Ni-Sn TLPS bonding, and their analytic solutions were obtained. Based on the Ni3Sn4 growth kinetics, a parameter uSn called transformed rate of Sn was defined. It was proved to be a more proper kinetic parameter to precisely characterize the kinetics of isothermal solidification in the Ni-Sn TLPS bonding. Furthermore, by measuring the melting enthalpy and thus determining the residual mass of the Sn component, the Ni3Sn4 growth kinetics and isothermal solidification kinetics were experimentally investigated to verify the theoretical model. The theoretical kinetics was confirmed to coincide well with the experimental results, and both are similar to exponential law. As the isothermally sintered temperature rises or the initial Ni particle size decrease, the kinetics of the Ni-Sn TLPS bonding process quickens. The mass ratio of Ni to Sn has no effect on the growing kinetics of the Ni3Sn4 layer, but on the isothermal solidification kinetics. [GRAPHICS]

Automated summary

In this study, the kinetics of Ni3Sn4 growth and the isothermal solidification kinetics in Ni-Sn transient liquid phase sintering bonding process were investigated. A kinetic model and parameter were established to describe the growth and isothermal solidification of Ni3Sn4. The experimental results confirmed the accuracy of the theoretical model and showed that the kinetics of TLPS bonding process can be accelerated by increasing the sintering temperature and decreasing the particle size.