Role of Ti in direct active bonding of SiC substrate using Sn-Ag-Ti alloy filler

作者：Cheng, L. X.^*; Ma, K. B.; Yue, X. J.; Li, Z. L.; Li, G. Y.

来源：Journal of Materials Science: Materials in Electronics , 2022, 33(6): 3331-3347.

DOI：10.1007/s10854-021-07533-7

• MICROSTRUCTURE
• TITANIUM

Low-temperature active bonding of silicon carbide substrate using Sn3.5Ag4Ti(Ce,Ga) active solder filler was carried out at 250 degrees C and 420 degrees C in air, respectively. The microstructure of the interface, the element distribution, and the new compounds formed at the interface had been investigated. The obvious segregation of titanium at the silicon carbide (SiC)/Sn3.5Ag4Ti(Ce,Ga) interface was observed for both soldering temperatures, in which the segregation rate at 420 degrees C is faster than that at 250 degrees C, because the diffusion coefficient of Ti is an exponential function of temperature. Results of transmission electron microscope analysis show that the reactants at the interface of SiC/Sn3.5Ag5Ti(Ce,Ga) of the joint soldered at 250 degrees C for 60 min were not observed although the segregation of Ti existed at the boundary. However, the TiC, Ti5Si3, and TiSi2 were found to be discontinuously formed at the interface for the joints soldered at 420 degrees C for 30 min. The work of adhesion of Ti on the surface of SiC is calculated, which might be inferred that the joining could be accomplished by chemical adsorption of titanium at the SiC/Sn3.5Ag4Ti(Ce,Ga) interface, regardless of whether an interfacial reaction layer is formed or not. The shear strength of the joints soldered at 420 degrees C is higher than that at 250 degrees C. This indicates that the formation of the reaction products plays a critical role to obtain more reliable bond between SiC and Sn3.5Ag4Ti(Ce,Ga), although it is not a necessary condition to realize bonding with reasonable strength.

• 单位
  华南农业大学