The friendly folks over at the Weller blog posted a great article today explaining what’s inside a soldering tip — and why. Something I was surprised to learn: while copper conducts heat well, it doesn’t do so well holding up against tin — hence the layer of iron around the copper tip. It seems as though the iron layer is the main factor determining the longevity of a tip.
If you spend any time at all with an iron in your hand, this is a must read.
The Architecture of a Soldering Tip [Weller Blog]