How Soldering Works: Glue for Metal

To connect two copper wires, you might twist them and tape them. Mechanical connection? Maybe. Electrical connection? Terrible. You need Solder.

Molten Metal

Solder is an alloy (usually Tin and Lead/Silver) that melts at ~370°F. Crucially, it is conductive. But you can’t just drip it on like wax. You must heat the wires until they are hot enough to suck the solder in (“Wetting”).

The Magic of Flux

Copper oxidizes (rusts) instantly in air. Solder hates rust. It balls up. Flux is an acid paste inside the solder wire.

1. It melts first.
2. It boils away the rust.
3. The clean copper is exposed.
4. The solder flows into the copper pores, creating a molecular bond. It’s not just “sticky metal.” It’s a chemical fusion.