Abstract: As wide-bandgap power devices such as SiC/GaN have developed toward high power density, high current, and high voltage, higher requirements have been imposed on packaging substrates. Silicon nitride (Si₃N₄) ceramics have been widely used in electronic packaging due to their excellent mechanical properties. Active metal brazing has become an important metallization method for Si₃N₄ ceramic substrates because it enables high interfacial bonding strength and thick-copper-layer brazing. In this paper, the materials, processes, microstructures, and properties of copper-clad AMB-Si₃N₄ ceramic substrate were systematically reviewed. The material selection, fabrication processes, and interfacial reaction mechanisms of Si₃N₄ were summarized, and the failure behavior of substrates under thermal cycling was evaluated. Additionally, the performance differences among industrialized products both domestically and internationally were reviewed, along with the quality consistency challenges faced in the large-scale manufacturing of copper-clad AMB-Si₃N₄ ceramic substrate. Furthermore, the evaluation methods and major failure modes for void ratio, peel strength, warpage, and thermal cycling life were summarized. Finally, the development directions and engineering challenges of copper-clad AMB-Si₃N₄ ceramic substrates in high-temperature and high-power electronic packaging were discussed, providing a reference for promoting the industrialization of copper-clad AMB-Si₃N₄ ceramic substrates.