[MarkMarine]

Depends on the components. You need to get enough heat into the joint that both sides are hot (pad and component) but not enough that you burn up a sensitive part. The hack people use, wetting the joint with solder by touching it to the iron can lead to a cold joint. Don’t do that.

Turn your iron up (I use 675) and ensure you’re touching the pad first, it’s a much larger heat sync. Lean the tip of the iron up to the component leg, give it a second and then feed solder into the other side of the leg, letting the leg of the component melt the solder and flood the joint. I use flux if I’m really worried about the joint, the fluid transfers heat better. There should be a clear fillet arcing between the pad and leg of the component, solder should be wet 100% around the pad and gracefully blend into the component leg. The joint should not look sandy or dirty or have bad surface finish.

[ahartmetz]

Lead-free solder will have a dull surface even on a good joint though, no? IMO worth mentioning. Not grainy or with visible "fault lines", but dull.

[MarkMarine]

yes, dull, but not rough or grainy that is exactly correct. It should be uniform, no grains or chunks, no crystal structure, no boundaries but smooth.

[Hackbraten]

> Turn your iron up (I use 675)

I felt a little puzzled about this but then it hit me that you probably meant Fahrenheit.

To spare others the conversion: 675 °F is roughly equal to 350 °C.

[andrelaszlo]

I solder very rarely and quite badly, but switching to non-lead solder just made it impossible to get good joints. I had to get a better iron, nothing fancy but with higher effect, meaning I can get to a higher temperature faster without turning the whole PCB into mush.