Abstract:With the development of 5G/6G communications and high-density electronic packaging, low-temperature co-fired ceramic (LTCC) devices require higher performance in high-frequency signal transmission, high-density integration, and reliable service. Internal electrode paste is a key material in LTCC multilayer interconnect structures, and its composition and co-firing behavior directly affect the electrical conductivity and service reliability of the electrodes. Compared with noble-metal electrodes, Cu is emerging as an important direction for LTCC internal electrodes because of its lower cost and stronger resistance to electrochemical migration. However, its susceptibility to oxidation also increases the difficulty of material composition design and co-firing control. Based on the technical background of the transition of LTCC internal electrode materials from Au and Ag to Cu, this paper reviews the progress in the component design of organic vehicles, inorganic binders, and conductive phases in copper pastes for internal electrodes. It focuses on the oxidation resistance, sintering densification, co-firing compatibility, interfacial bonding behavior, and related influencing factors during co-firing, and further summarizes the current research challenges and future development directions.