Adsorption and interface reaction in direct active bonding of GaAs to GaAs using Sn–Ag–Ti solder filler

Abstract

The element diffusion behavior, the interfacial evolution and mechanical properties of the joining of gallium arsenide (GaAs) with Sn3.5Ag4Ti(Ce,Ga) alloy filler at 250 °C in air were investigated. The interfacial microstructure, elemental diffusion and absorption, interface reaction and evolution were analyzed in detail. Titanium (Ti) and gallium (Ga) element were found to obviously take part in the active bonding between GaAs substrate and Sn3.5Ag4Ti(Ce,Ga) alloy filler. According to the transmission electron microscopy analysis, the titanium elements were observed to successively segregate at the interface, while some of the element Ga included in GaAs to dissolve into the molten alloy. In addition, there is a resultant formed discontiniously along the interface which was identified as Ga 4 Ti 5 , but no arsenic compounds were observed. The joining mechanisms related to the adsorption and reaction were discussed based on the thermodynamics theories, the molecular dynamic (MD) model and the reaction product controlled (RPC) model. The analysis results show that the RPC model was a special form of MD model, both the chemical reaction and the adsorption of active elements may control the reactive wetting of Sn3.5Ag4-Ti(Ce,Ga) filler alloy on GaAs substrate together. In order to better understand the interfacial evolution of bonding, a simple interfacial evolution model between GaAs substrate and Sn3.5Ag4Ti(Ce, Ga) active solder was established. Finally, the effect of holding time on shear strength was investigated and the maximum shear strength of 23.32 MPa was obtained when soldered at 250 °C for 1 h. The interface separation could be caused by the mixed fracture mechanism.

Study of Wettability and Solderability of SiC Ceramics with Ni by Use of Sn-Sb-Ti Solder by Heating with Electron Beam in Vacuum

“…This base is used to join the majority of metals, ceramics and composites. This solder was also used in the work of Cheng et al [ 13 ] for soldering GaAs. Titanium (Ti) and gallium (Ga) were found to obviously take part in the active bonding between the GaAs substrate and the Sn3.5Ag4Ti(Ce, Ga) alloy filler.…”