Guide
Which Solder Wire Should You Use With Your Iron?
Published:
TL;DR
- 60/40 leaded solder melts at a lower temperature and is easier to learn on than lead-free.
- Lead-free (typically SAC305) is required by law for anything manufactured commercially for sale under UK/EU RoHS rules, hobby use isn't restricted the same way.
- 0.5-1.0mm diameter flux-core wire suits most general electronics work.
- Store solder wire somewhere dry; oxidised, tarnished solder flows and wets poorly.
Leaded vs lead-free
60/40 (tin/lead) solder melts at a lower temperature than lead-free alloys and flows more predictably, which is why it's the easier option to learn on. It's still legal to buy and use for personal, non-commercial soldering in the UK.
Lead-free solder, most commonly a tin/silver/copper alloy like SAC305, is what RoHS regulations require for anything manufactured and sold commercially. It needs a slightly higher iron temperature and takes more practice to get consistently good joints with, since it's less forgiving of a joint that's marginally too cool.
Wire diameter
0.5-0.8mm wire gives better control for fine electronics and PCB work, since it's easier to feed a small, precise amount of solder into a small joint. 1.0mm+ wire is better suited to larger joints, thicker wire, or general repair work where you're feeding more solder at once.
Storage
Solder wire oxidises over time, especially if it's been left out in a humid space. Oxidised solder looks dull rather than shiny and doesn't flow or wet as cleanly. Keep the reel in its original packaging or a sealed bag when it's not in use.