Air-sinterable copper pastes for next-generation electronics: a review

Abstract

In recent years, in addition to the pursuit of miniaturization and integration, electronic devices have exhibited an increasingly prominent demand for high power and intelligent functions, which has become a key driving force for the development of next-generation products. Metal pastes, which exhibit low-temperature sinter-joining behavior, excellent thermal and electrical conductivity, and favorable mechanical compliance, have emerged as promising interconnection materials for next-generation electronics. Among metal pastes, copper pastes are regarded as ideal candidates for replacing traditional solders due to their high electrical conductivity, excellent resistance to electromigration, and significant cost advantages. However, the high chemical reactivity of copper makes it highly susceptible to oxidation, and current sintering processes require reducing or inert atmospheres. Air-sinterable copper pastes overcome this limitation by enabling sintering under ambient conditions, thereby reducing equipment investment and operational costs while enhancing manufacturing flexibility for industrial-scale production. In this work, a comprehensive overview of recent advances in air-sinterable copper pastes is presented. Specifically, the design strategies are systematically elaborated, encompassing the fabrication of anti-oxidation copper particles, including organic coating, metal core–shell structures, and alloying approaches. The development of reductive solvent systems, such as carboxylic acids, polyols, and their composites, is also discussed. Furthermore, sintering processes compatible with air conditions including pressure-assisted sintering, laser sintering, and other emerging sintering approaches are analyzed in detail. Finally, their current application status in flexible electronics and power devices is summarized, followed by a discussion on key challenges including mechanism elucidation, equipment standardization, and formulation-process optimization for industrial implementation.