[phaer]

> A bigger problem is that you should never use leaded solder to repair boards that have been soldered with lead-free, which means pretty much every board out there that has been manufactured in the last 20-30 years or so.

I am unlikely to every try this, but curious: Why is that, what would happen?

[jwr]

It results in unreliable joints that will cause problems over time.

[Kirby64]

Source? If you’re doing board repairs and adequately clean the previous components then I see little reason why adding leaded solder to the very small amount of remaining lead free solder would be a problem. If you have a full lead free joint and then add a bit of leaded solder, sure… but how many people are doing board repairs like that?