In-situ experimental study on the microstructure evolution of AlN-Cu composite during microwave sintering

Abstract

Due to its combination of high thermal conductivity and electrical conductivity, the AlN-Cu composite material exhibits enormous application potential in the field of electronic packaging. Its interfacial properties directly determine the reliability of devices. In this study, microwave sintering and a rapid SR-CT in-situ device were used to real-timely observe the entire process of microstructural evolution in AlN-Cu materials. The research found that microwave sintering can achieve bonding at 600℃ within 6 min to form an intermediate phase of CuAlO₂; The initial volume of copper particles regulates the reaction rate by influencing the effective microwave volume. The difference in dielectric constant between AlN and Cu triggers interfacial polarization, reconstructs the microwave energy distribution, and accelerates the reaction. When the radius ratio of Cu to AlN particles is close to 1, the actual microwave heating efficiency is the highest; there exists an optimal radius ratio (R_Cu:R_AlN = 1) that maximizes the actual thermal power, balancing electric field enhancement and effective volume attenuation. This study provides a fundamental reference for designing the particle size of AlN-Cu composite materials and optimizing the microwave sintering process.