[sdiy] mixing metals

[Tavys Ashcroft]

Is there any negative effect on longevity when using lead and
lead-free components together with lead solder?  I know that some
metal alloys don't play well together and can cause to corrosion.

I'm ordering some parts and RoHS-compliant ones are quickly overtaking
old-fashioned leaded parts.  Some leaded ICs are stock-on-shelf only
and will not be manufactured again.  I just want to know if it's safe
to start mixing or if I'll need to switch over completely, all at
once.

Also, any recommendations on lead-free solder?  I've been using
Kester's lead solders for a while, so I'm not sure which lead-free
ones are any good.  I like the no-chemical wash kind (331, which can
be washed with warm water) and the no-clean kind (245, even though it
smells funny).  The last time I used lead-free soler was a while back,
and it didn't seem very good at the time... I'm sure it must be better
by now.

Thanks,
-Tavys