Leads that come pre-tinned have to have a compatible solder on them. When you buy components now, the suppliers declare whether they're RoHS (lead-free) or not.

Leads that come pre-tinned have to have a compatible solder on them. When you buy components now, the suppliers declare whether they're RoHS (lead-free) or not. You can't easily buy eutectic (lead bearing) tinned parts anymore because it's easier to have the global supply chain conform to the EU regulations. Note that military parts often come with gold plated leads which you can use your choice of solder on. You can't easily buy such things anymore from commercial suppliers.