Filler‐Regulated Pore Evolution Kinetics and Reliability Enhancement Mechanism of Sintered Ag Joints Revealed by Phase‐Field Simulation

Abstract

ABSTRACT Wide‐bandgap semiconductor power devices generate substantial heat, demanding reliable thermal interface materials. Pressureless sintered Ag pastes offer high melting point and excellent thermal conductivity, but their inherent high porosity degrades reliability, and the pore evolution mechanism remains unclear. In this study, by combining microstructural characterization (porosity, pore size, voids) with phase‐field simulations, we systematically compared the reliability of conventional sintered Ag joints and carbon‐added sintered Ag joints C–added Ag joints). The porosity of pure Ag joints decreases significantly with increasing sintering temperature or time, from 21.67% to 14.45%. In contrast, C‐added Ag joints show only a slight reduction (from 19.55% to 15.53%). After thermal cycling (TC), stress from porosity reduction creates large voids in pure Ag joints (void area ratio up to 27.74%), while C‐added Ag joints exhibit negligible changes. The pore evolution of pure Ag joints follows the Coble‐ Burke coupled model, which couples grain growth with densification to obtain the kinetic equation, providing a predictive porosity‐time relationship. Carbon addition effectively suppresses pore coalescence and Ostwald ripening, leading to high reliability. This work guides future lifetime prediction and reliability studies for sintered Ag joints.