Thermal Optimization of Polycrystalline Aluminum Nitride Ceramic Substrates for Power Electronic Packaging

The power devices in artificial intelligence computing equipment and new energy vehicles require substrates that possess both electrical insulation and heat dissipation capabilities. The heat dissipation performance of polycrystalline aluminum nitride (AlN) is influenced by both the preparation of the ceramic and the packaging structure. This article compares the results and limitations of related studies along four paths: powder oxygen control and debinding, sintering additives and grain boundary phase regulation, sintering and post-processing, and packaging interface. Existing research indicates that reducing lattice oxygen requires considering densification; additives and sintering processes also change pores, second phases, and mechanical properties, so it is not advisable to directly compare thermal conductivity values without considering the raw materials and test conditions. After entering the power module, the thermal conductivity of the substrate or the strength of the joint may increase, but this cannot alone prove that the module junction temperature has decreased; thermal cycling may also cause cumulative deformation. The selection of high-power chip substrates requires a comprehensive evaluation of the ceramic matrix properties, interface thermal resistance, module junction temperature, and joint stability.