How do you hand solder correctly? Basic technique step by step

How do you solder step by step correctly?

In hand soldering, heat goes into the joint first, not into the solder. The tip heats the pad and the component lead at the same time, then the solder wire is fed to the heated spot. The solder melts at the joint itself and flows cleanly around pad and lead through the heat that is present.

The most common beginner mistake is to melt solder onto the tip and then dab the blob onto the spot. The flux boils off before it can work, and the result is a cold, poorly wetted joint. The correct way: tip and solder touch the spot from two sides, and the solder melts on the heated metal.

• Tin the tip: wet the clean tip with a little fresh solder so heat transfers well.
• Make contact: place the tip so it touches both the pad and the component lead.
• Heat: bring both metal surfaces up to soldering temperature for about a second.
• Feed solder: bring the wire to the joint, not onto the tip, and let it melt.
• Let it flow: add enough solder until a small concave fillet wets pad and lead.
• Remove solder: take the wire away first, then lift the tip.
• Hold still: let the joint solidify without movement, or it turns into a cold joint.

What temperature, tip and flux do you need?

A clean result depends on three things: the right temperature, a clean tinned tip and enough flux. For lead-free solder the tip temperature is usually 350 to 380 °C, because these alloys melt hotter than leaded ones.

The tip must be clean and tinned so heat transfers quickly. An oxidised, black tip barely conducts heat and forces you to heat longer. Between joints, wipe the tip on a damp sponge or brass wool and re-tin it right away. Flux, usually built into the solder wire as a core, dissolves oxides and makes the solder spread flat instead of balling up.

You can recognise a good joint by a smooth, shiny surface and a concave, slightly drawn-in fillet that fully wets pad and lead. With lead-free solder the surface may look a little duller, which alone is not a defect. See the solder joint inspection guide for grading details.

What beginner mistakes exist and how do you solder ESD-safe?

Most beginner mistakes come from the wrong order, too much solder or too much heat. The table below maps the typical mistakes to their cause and the fix.

Electronic components are sensitive to electrostatic discharge. Hand soldering is therefore done ESD-safe: a grounded soldering station, an ESD mat and a wrist strap at a grounded workspace. This lets charges drain in a controlled way instead of damaging the parts.

• Use a grounded soldering station with an equipotential tip.
• Bond the ESD mat and wrist strap to a common ground point.
• Handle parts on a dissipative surface, not on ordinary plastic.
• Check the grounding of mat and strap before you start.

Frequently asked questions