Phase-field study of IMC growth in Sn–Cu/Cu solder joints including elastoplastic effects

Abstract

In this article, we aim to study the problem of the growth of intermetallic phases in solder joints undergoing mechanical deformation, using a phase-field model for multi-phase systems that can treat diffusion, elastic and plastic deformation. A suitable model is formulated and applied to Sn-Cu/Cu lead-free solder joints. The growth of the intermetallic layers during solid-state annealing is simulated for different strain states. We assess the values of stiffness tensors available in literature and perform ab initio calculations to support the selection of reasonable values from literature. We also perform a parametric study with different eigenstrain values and applied strains. We find that there is a significant effect of the considered eigenstrains and applied strains on the growth kinetics of the system and parabolic growth kinetics is followed in cases where the intermetallic layers grow. We thereby establish the importance of strain in the growth of intermetallic layers and the need for more targeted experiments on the role of strain in the reliability of the solder joint.

Integration of machine learning with phase field method to model the electromigration induced Cu6Sn5 IMC growth at anode side Cu/Sn interface

“…Though the formation of Cu3Sn IMC between FCC phase and Cu6Sn5 IMC at anode interface is also thermodynamically favorable, the diffusion based growth kinetics of Cu3Sn IMC (interfaced between two solid state phases) is quite negligible compared to Cu6Sn5 IMC (remaining in contact with the LIQUID phase too). However, at lower temperatures, when both Cu substrate and Sn solder are in solid states, and the experiment is performed for a few days, the layer thickness of both Cu3Sn and Cu6Sn5 IMCs are comparable [27] . In this present study, when the solder is in LIQUID state and the experiment is performed for 1 h, the growth of only one IMC , namely, Cu6Sn5 IMC , is considered at the anode (Ref.…”

A Review on Phase Field Modeling for Formation of η-Cu6Sn5 Intermetallic

“…Generally, the multi-phase field model studying the evolution of microstructure involves three phases, Cu(S), liquid Sn(L), and η-Cu 6 Sn 5 with multiple variants, whose structures are characterized by a set of non-conserved order parameters since the reaction 6Cu(S) + 5Sn(L) → Cu 6 Sn 5 is diffusion controlled. The premise of most phase field modeling is to determine whether the phase transition process can occur, that is, whether the free energies of the reacting phases and their products have intersection in the relative phase diagrams [9,16,[21][22][23][24]. Figure 4 shows the chemical free energy of Cu(S), liquid Sn(L), and η-Cu 6 Sn 5 during reaction 6Cu(S) + 5Sn(L) → Cu 6 Sn 5 under different conditions.…”

“…6Cu(S) + 5Sn(L) → Cu 6 Sn 5 is diffusion controlled. The premise of most phase field eling is to determine whether the phase transition process can occur, that is, whet free energies of the reacting phases and their products have intersection in the r phase diagrams [9,16,[21][22][23][24]. shows the chemical free energy of Cu(S), liquid Sn ( η-Cu6Sn5 during reaction 6Cu(S) + 5Sn(L) → Cu 6 Sn 5 under different conditions.…”

“…The stochastic nature of nucleation is then approximated by unity "minus" the zero-event probability of a Poisson distribution, which is applied to replace the Langevin noise [29]. The expression of Poisson nucleation probability P n and nucleation rate I are as follows [22,23]:…”

A phase-field approach to study BCC precipitate evolution in FCC AlxCrFeNi medium entropy alloy including elastic effects

“…The interpolation functions and are formulated as [10] and These interpolation functions play a key role at the diffuse interfaces, where they interpolate various material properties between their values in the two phases. The last term represents the elastic contribution to the total free energy, formulated for a multiphase system and following a micro-elasticity approach [11],…”