 What's the difference between lead and lead-free solder? Well, besides the obvious, compared to 6040 lead solder, lead-free solder has a higher melting point, and the joints it produces tend to have a rougher appearance. Lead-free solder also comes in a variety of alloys, such as tin copper, which costs a bit more compared to leaded, or tin silver copper, which costs significantly more but has benefits such as improved joint strength, resistance to corrosion, and improved wetability, which is the tendency of the solder to flow onto a heated surface. Also, the flux used in lead-free solder tends to be more toxic to humans, so be sure to employ a fume extractor. But you already do that, right? Yes? You're nodding? Good.