I'm always having problems soldering wires to connectors. I've read through the Solder wont stick question, but nothing there seems to have helped.
Here's my procedure:
- If the connector is being difficult, I rub the surface of the connector with fine-grain sandpaper to clear any oxidisation.
- Get my iron up to about 175 deg C (it's a temp-controlled iron)
- Brush the tip across a damp sponge.
- Add a small spot of solder to the tip.
- Line up the wire to the connector, usually with a clamp.
- Hold the tip of the iron on the connector for a short time.
- Push some solder onto the wire at the edge of the tip, so the solder melts onto the wire.
- Remove the iron.
- Brush the tip across the sponge again to clean off the excess solder.
The problem I'm having is that the solder just doesn't stick the wire to the connector. It usually holds for a second, then unsticks from the connector as soon as the wire moves. I've tried more solder, less solder, different solder - same issue.
I've started to notice the same issue when soldering onto stripboard, too. The flow seems to be poor, the solder doesn't look shiny, and it's all rather viscous.
Am I doing something wrong? Is my iron / tip bad?