Modelling of transient liquid phase bonding in binary systems—A new parametric study

Abstract

An established mathematical model, describing the rate at which transient liquid phase bonding (TLP bonding) progresses in binary alloy systems, is subjected to careful scrutiny. It is shown that the process can be characterised using just two dimensionless parameters. An advantage of such dimensionless characterisation is demonstrated by analysis of the solution for solidification of semi-infinite systems. It is known that analytical formulae for the rate at which the liquid region solidifies are valid only for certain restricted cases. This is investigated by numerical modelling, and the requirements for the formulae to be applicable are rationalised. Maps presented here can be used to determine whether the semi-infinite solution would provide an acceptable approximation for any given system. Information is also presented concerning optimal combinations of phase diagram characteristics, diffusivities and system dimensions required for rapid TLP solidification, which can be used to identify the best melting point depressant (MPD) materials to use for particular TLP requirements. The analysis reveals that, as a consequence of their higher solubilities, elements forming substitutional solutes in the parent plates may often allow faster TLP solidification than those forming interstitial solutes, despite the fact that the latter group normally exhibits much higher diffusivities.

Overview of transient liquid phase and partial transient liquid phase bonding

“…On the other hand, analytical models of TLP bonding indicate that the isothermal solidification process time is roughly proportional to the square of the interlayer thickness [9,18,19,25,36,44,86,104,110,114,124,138,161,173,175,176]; experimental data often corroborates this trend [3,26,43,44,71,86,88,153]. Therefore, to minimize bonding time, an interlayer slightly thicker than the critical thickness is ideal.…”

“…Numerical models can account for some of the complexities of TLP bonding to accurately predict bonding kinetics [7,8,161,162,168,173,176,179,182,183] and can even be extended to multi-component systems [174,184]. Despite the complexities and extra time required in numerical modeling, especially for multi-component systems, the limiting factor is most often the lack of necessary diffusion data [7,8,178].…”

Transient Liquid Phase Bonding of Magnesium Alloy AZ31 Using Cu Coatings and Cu Coatings with Sn Interlayers

“…Therefore, alternative joining techniques have been implemented to achieve solid joints with higher joint strength. One of those alternative techniques is transient liquid phase bonding (TLP), which was widely investigated both theoretically and experimentally for certain similar and dissimilar alloys [5][6][7][8][9]. It was agreed that the choice of the interlayer or coatings is a critical factor in achieving a successful TLP bonding for a certain alloy.…”

Effect of Interfacial Hardness on Failure Modes of Liquid Phase Diffusion Bonded Sn/Sn with Bi Filler

“…However, the real joining surface had large and small irregularities and use big plastic deformation to ll these gap or couldn t but joint it in a liquid phase state. Therefore, in this study, we tried the application to the micro junction of the liquid phase diffusion joining method with the results by the joining of the large material [14][15][16][17][18][19][20] . An advantage of the liquid phase diffusion joining method is that the melting point of the junction rises when the joining process is nished.…”