Study on the correlation between spreadability and wetting driving force of Ni-GNSs reinforced SnAgCuRE composite solder.

[Display omitted] • The dynamic spreading processes of Ni-GNSs reinforced SnAgCuRE composite solders on Cu substrate were characterized. • The formation mechanism of the precursor film in the dynamic spreading processes was revealed. • The correlative equation between spreading and wetting driving force of composite solder was established. To save test time and cost, spreading area method and wetting balance method were used to study the wetting characteristics of Ni-GNSs/SnAgCuRE composite solder under different parameters and explore the correlation between spreadability and wetting driving force of the composite solder. The results showed that the composite solder had good spreadability on the Cu substrate under 270–280 °C and water-clean flux, and they had good wetting adaptability to Cu wire under the tin bath temperature of 270–280 °C, dipping time of 6 s and dipping speed of 20 mm/s. The results satisfied the requirements of production in micro-connection field. The dynamic spreading processes of Ni-GNSs/SnAgCuRE composite solder consisted of three stages: initial slow shrinkage, rapid expansion and gradual equilibrium. Added appropriate amount of Ni-GNSs into the solder alloy, they adsorbed on the surface of Ag 3 Sn particles to form a precursor film at the three-phase interface, which was conducive to spread. The correlation equation between spreadability and wetting driving force of composite solder was established. According to the spreading area of the composite solder on the Cu substrate, the wetting driving force and wetting balance of the immersion wetting processes could be analyzed and vice versa. [ABSTRACT FROM AUTHOR]