Finite element analysis of the effect of TiC or graphite modified composite fillers on the thermal residual stress of AMB ceramic substrates

Abstract Ag–Cu–Ti–In + X (X = TiC, graphite) composite fillers are developed to improve the comprehensive mechanical performance of active metal brazing (AMB) ceramic substrates (AlN/filler/Cu). This paper reports the effect of TiC or graphite modified composite fillers on the thermal residual stress of AMB ceramic substrates. Models based on force and moment balances and thermomechanical finite element analysis are applied to estimate the distributions of residual stresses. Results indicate that the graphite modified composite filler provides better thermal residual stress reduction on AMB ceramic substrates compared to the TiC modified composite filler. Furthermore, submodels are established to investigate the mechanism of the influence of TiC or graphite particles on the residual stress of AMB ceramic substrates. The stress distribution trends obtained from the submodels are consistent with those obtained from the corresponding global simulations, that is, stress is concentrated on the ceramic side. This further proves the rationality of adopting the submodels. It is indicated that softer graphite particles can be appropriately deformed like a pore structure to decrease stress. For TiC particles, higher hardness and stronger load transfer ability can alleviate the deformation of a metal layer, and the compressive stress concentration transfers to the particles.