60/40 rosin core solder in .040" (1mm) diameter — the standard choice for soldering LEDs, resistors, and through-hole PCB components. The 60% tin / 40% lead alloy melts at 370°F (188°C), flows smoothly into joints, and produces reliable, shiny solder connections every time.

The built-in rosin flux core cleans the joint as you solder, promoting proper wetting without needing separate flux for most LED and wire-to-wire connections. The .040" diameter is thin enough for precise work on 3mm and 5mm LED leads, resistor legs, and fine-pitch PCB pads, while still feeding quickly enough for larger connections like wire splices and terminal posts.

Best For

Soldering LED leads to wire, PCBs, and prototype boards
Attaching resistors, capacitors, and other through-hole components
Wire-to-wire splices and tinning stranded wire ends
Model railroad wiring and DCC decoder installations
Guitar pedal builds and audio electronics assembly
General hobby electronics and Arduino/ESP32 projects

Soldering Tips

Heat the component and pad with your iron first, then touch solder to the heated joint — not the iron tip
A good joint looks smooth and shiny, not dull or blobby
Use a damp sponge or brass tip cleaner to keep your iron tip clean between joints
For LED leads: tin both the wire and the LED lead first, then join them for a strong connection