Received from Dave at 11/6/2019 15:02 UTC:
Harvey,
I was hoping to avoid "lead free" solders altogether but I am sure there is a good reason for them.
The reason is environmental... lead being harmful.
Can a lead free component be soldered to a copper clad pcb with tin/lead solder?
Absolutely yes. In reality it takes almost 3X as long to thoroughly wet a joint when soldering with ROHS solder than with the old tin-lead solder. Using tin-lead actually improves your chances of getting a good joint.
Or better yet, mixing thru hole and SMD components on the same board is not a problem I guess?
Not a problem for hand soldering. But tin-lead and ROHS solder melt at different temperatures and take different times to assure a thoroughly wet joint, so using a reflow oven for soldering with different types of solder isn't adviseable.
Jim H
