Wettability in lead-free soldering: Effect of plasma treatment in dependence on flux type.

[Display omitted] • Effect of plasma treatment and six different fluxes on solder wetting was studied. • Copper samples treated by N 2 /H 2 plasma exhibited excellent wetting with any flux. • Even expired fluxes can be successfully used for soldering of plasma-treated connectors. • Flux cannot be omitted from soldering due to the remaining thin oxide/organic layer. • Plasma treatment allows much less active flux to be used in the soldering process. To enhance the solderability, highly active fluxes are commonly employed in lead-free soldering. However, there are industry-wide efforts to use less active fluxes to avoid possible issues associated with corrosion processes and minimize subsequent cleaning processes, thereby reducing potential environmentally harmful waste. Therefore, in this study, the effect of the plasma treatment (N 2 /H 2 97:3) on the wettability of the soldered surface (copper connectors) was investigated. Wettability measurements were conducted using SAC305 solder alloy and six different fluxes. The wetting balance test revealed a significant improvement in wetting for all tested fluxes, regardless of their composition. On the other hand, non-wetting occurred when no flux was applied to the plasma-treated surface, attributed to a thin residual oxide layer detected by X-ray photoelectron spectroscopy. Thus, the plasma treatment of the surface supports the flux effect, which cannot be entirely omitted from the soldering process. However, incorporating plasma treatment in the soldering process allows for the use of much less active or even expired fluxes. [ABSTRACT FROM AUTHOR]