Stay-Brite solder is Sn-3.5% Ag (lead free) and is good where higher strength and fatigue resistance is required. Standard eutectic Sn-Pb solder (electrician solder) is good enough for the cable, and it's easier to work with too. Rosin flux can be used with both solder types. I did not use the bottle of acid flux that came with my Stay-Brite solder kit so far.