A directive introduced by European bureaucrats with very little science behind it, requiring all products to use lead-free solder. It also placed restrictions on some elements such as cadmium and mercury.
The most notable change was the
ban of leaded solder though, and it resulted in longer production times for PCB fabrication, many more products failing and requiring BGA reballing (e.g Xbox
360)
Idiots hang onto it for "
safety" but it has been shown that it doesn't cause health
issues unless you scatter it everywhere. As for how "environmentally friendly" it is, it causes more products to get thrown away, the opposite of what it was trying to accomplish.
It can be reflowed or wave soldered
pretty easily but is not practical at all for any hobbyist use.
It has a lot of downsides:
1.) More brittle solder joints
2.) Never desolders properly
3.) High
heat damages components
4.) Grows
tin whiskers more easily, although this is not really an issue in most things
5.) More flux required, which creates lots of fumes and can cause occupational asthma
