Phase-field modeling of reactive wetting and growth of the intermetallic Al2Au phase in the Al-Au system

Abstract

When an Al-droplet is in contact with an Au-solid substrate, the liquid phase reacts with the substrate and an intermetallic layer is formed at the solid-liquid interface due to diffusion and reaction. This phenomenon has been commonly observed in the soldering process and the wetting is termed as reactive wetting, in contrast to the inert wetting where the droplet does not react with the base materials and the substrate is flat. Young's law can be used to interpret the contact angle in the static state, but is not able to predict the dynamics in the process of reactive wetting. In this work, we present a multiphase model including phase transition and fluid dynamics to investigate the effect of the formation of the intermetallic Al 2 Au phase and capillary flow on the reactive wetting in the Al-Au system. In order to capture phase boundaries of solid-, liquid-and intermetallic-vapor, phase-field simulations are performed based on a ternary (Al-Au-X) phase diagram concept and using experimental data. It has been found that the increase of both the liquid-intermetallic interfacial tension as well as the capillary flow lead to an inhibition effect for the growth of the intermetallic phase.

Investigation of Equilibrium Droplet Shapes on Chemically Striped Patterned Surfaces Using Phase-Field Method

“…In Figure b,c, the equilibrium states of a droplet on surfaces with equilibrium contact angles θ e,wet = 41° and θ e,dry = 106° are presented, respectively. The contact angles of droplets at the final state on the two surfaces are measured by using a modified marching square algorithm. , Figure d shows the simulation results for droplets with the Cahn number Cn varying from 0.03 to 0.2, which is achieved by varying the resolution Δ x from 0.6 to 4. The red circles and blue squares represent the simulation results on surfaces with equilibrium contact angles θ e,wet = 41° and θ e,dry = 106°, respectively.…”

“…Droplets deposited on homogeneous surfaces with equilibrium contact angles ranging from 10 to 170° are simulated. At equilibrium, the contact angles are measured through a modified marching square algorithm. , The cosine of measured data versus (γ gs – γ ls )/γ lg is plotted in Figure . The simulation results are shown by the blue squares, and the red line depicts the theoretical prediction of Young’s law.…”

Growth behavior of preferentially scalloped intermetallic compounds at extremely thin peripheral Sn/Cu interface

“…This can explain the relative magnitudes of L max and H max for the different solder samples. Villanueva et al [25] and Wang et al [26], have performed phase field simulations to model reactive wetting, but still there is a dividing opinion about the actual start time of nucleation of IMCs at the interface during spreading procedure. Villanueva et al [48] and Wang et al [49], have assumed that dissolute wetting stage followed by intermetallic phase formation occur during total reactive wetting process; and thus ignore the competitive lateral spreading of intermetallics compound with respect to the contact line motion.…”

“…The evolution of non-conservative order parameters φ i for a two phase (case I: liquid Sn and Cu 6 Sn 5 phases; case II: liquid Sn and Cu phases) binary Cu-Sn system is described by the following Allen-Cahn equation [25,26].…”

The diffuse interface phase‐field model for in situ interlayer phase formations in low‐temperature reaction bonding of alumina laminates—A theoretical and experimental comparison

“…11 High temperature-pressure bonding ensures completion of reaction at interface but causes destructive occurrence of diffuse out of elements, 12 isolated voids, 6 interface movement, 13 kirkendall porosities, 14 deleterious reaction products, and severe volume change during reaction and local stressfiges. 15 A new approach of improving bond quality 16 and even decreasing bonding pressure and temperature 17 can be based on simultaneous reduction of interlayer materials/adjacent ceramic interface 18 and formation of homogeneous bonding products 19 with minimum mismatch with ceramic laminates.…”