A Multiscale Simulation Study on the Effects of Filler Coating on the Performance of Electrically Conductive Adhesive

Silver-coated copper (Cu@Ag) electrically conductive adhesives (ECAs), compared with conventional silver-based ECAs, provide an effective solution for improving economic feasibility and mitigating electromigration. However, the influence of the coating on electrical, thermal, and mechanical reliability of ECAs, particularly the coating failure mechanisms under thermo-mechanical loading, remains unclear. In this study, a parallel multiscale modeling approach combining finite element simulations and molecular dynamics analyses is used to explore the structure–property relationships of Cu@Ag ECAs. At the macroscopic scale, a Monte Carlo-based algorithm is developed to generate a parameter controllable three-dimensional filler–matrix model. The influence of silver coating thickness from 1 to 2.5 μm on volume resistivity and thermal conductivity is analyzed. The results show that only at higher filler content does the silver coating significantly enhance both electrical and thermal performance. Molecular dynamics simulations uncover a temperature driven transition in interfacial failure mechanisms. At 300 to 400 K, deformation is dominated by dislocation nucleation and FCC to HCP transformation in the Ag layer, accompanied by defect accumulation and strain induced amorphization, whereas dislocation activity in the Cu layer remains scarce. However, when the temperature rises to 500 K, the deformation mode shifts to interface sliding dominance, resulting in a marked decrease in the Cu/Ag interfacial shear strength. The findings highlight the critical roles of coating thickness, filler content, and curing temperature in dictating Cu@Ag ECA properties and provide guidance for the design and fabrication of reliable ECAs.