Off season skills: Learn how to Solder

[Jon Stratis]

Originally Posted by Jim Wilks

Given that lead-free solder always has a higher melting temperature than lead solder, I can't see the logic of this statement.

A cold solder joint results when the wire hasn't been heated up enough for the solder - you can melt the solder because the iron is hot, but it won't adhere to the wire properly if the wire is too cold. The most common way I've seen this done from my students is to put the solder directly on the iron, then touch the iron to the wire. It appears to work quicker, as the solder melts immediately and then is transferred to the wire... but the solder can then be pulled off very easily as it's mostly just sitting on the surface.

That's why it's important to always put the iron on the wire first, then feed the solder into the wire, not the iron. It takes a bit longer than the "easy" way, but you're guaranteed a good joint, and you can actually watch the solder flow through and all the way around a stranded wire.

That's also why working with lead solder is easier... the lower melting point of lead makes it easier and quicker to get the wire to the correct temperature for that solder.