Interfacial bonding mechanism and conductivity of low-melting Bi-B-Zn glass silver paste for electronic packaging

Given the widespread use of conductive silver paste in the fabrication of electronic packaging, it is critical to understand and accurately control the factors influencing the conductivity and interfacial bonding strength of the conductive layer, as well as the associated mechanisms. In this paper, the interconnection of the micro-arc oxidized insulating layer on the SiC_p/Al substrate with conductive silver paste is investigated. This paste with a composition of 35Bi₂O₃-50B₂O₃-15ZnO glass is applied to the micro-arc oxidation coating, and a conductive silver film is constructed via low-temperature sintering. The effects of varying glass phase content and sintering temperature on the microstructure, electrical conductivity, and interfacial bonding characteristics of the silver film are compared and analyzed. Results indicate that the silver film with low glass content has good electrical conductivity, reaching 2.90 ± 0.24 μΩ cm. Additionally, the interfacial shear strength of the silver film increases with higher glass content, reaching a maximum of 25.25 MPa, and increases with rising sintering temperatures, reaching a bonding strength of 25.33 MPa. An interfacial reaction between the micro-arc oxidation coating and the silver film forms Bi₂O₂SiO₃ and ZnAl₂O₄ phases, making excellent metallurgical bonding at the interface.