Soldering Si3N4 to Invar42 by a localized heating process

Abstract This study investigates the soldering process for joining silicon nitride (Si ₃ N ₄ ), a commonly used ceramic, to Invar42, a low thermal expansion alloy. The focus lies on analyzing interfacial reactions and evaluating the bonding performance of the Si ₃ N ₄ —Invar42 joint. Field emission scanning electron microscopy (FESEM) and energy‐dispersive X‐ray spectroscopy (EDS) were employed to examine the microstructure, elemental distribution, and chemical composition of the interfacial region. The results underscore the critical role of interfacial reaction layers in the soldering process. Mechanical testing (single lap offset, SLO, lap shear tests) was conducted to assess the bonding strength and mechanical integrity of the soldered joints. Furthermore, the thermal stability and reliability of these joints were evaluated through SLO tests at 300°C. This study contributes to the advancement of a user‐friendly, pressureless, localized heating and field‐deployable technique for soldering Si ₃ N ₄ to Invar42, thereby facilitating the fabrication of advanced engineering systems in industrial environments.