Learning basic soldering

What it is

Solder is a metal alloy that melts at a low enough temperature to flow around a joint and then freezes into a permanent electrical connection as it cools. Learning to make that joint cleanly is the single skill that unlocks almost all of maker electronics, from repairing a guitar pedal to building a kit from scratch.

A good joint is bright, smooth, and shaped like a tiny volcano around the component lead. A bad one is dull, rough, or blobby, and it is the root cause of most electronics failures. The technique is genuinely learnable in an afternoon, and the feedback is immediate, which is what makes it satisfying. Get a temperature-controlled iron (a Hakko FX-888D is the benchmark, but a TS100 does the job for less), set it to around 320 to 350°C for leaded solder, and practise on a cheap PCB kit costing €5 to €15. The one rule beginners always break: heat the joint, not the solder. If you melt solder onto the iron tip and dab it on, you get a cold, unreliable connection every time. The lead has to flow into a joint that is already hot enough to receive it.

How it works

Set the iron to 320 to 350°C for leaded solder, then tin the tip before the first joint by melting a small bead of solder onto it and wiping it on brass wool. A clean, tinned tip transfers heat efficiently; a dull, oxidised one does not, and most beginner frustration traces straight back to a dirty tip that will not wet. Use rosin-core solder around 0.6mm diameter, and keep the brass wool, not a wet sponge, within reach because the sponge cools the tip every time you clean it.

The actual joint goes like this. Place the component lead through the pad, press the iron against both the lead and the copper pad at once to heat them together, then feed solder into the joint itself, not onto the iron tip. The solder flows around the lead and pad and forms a bright, smooth little volcano shape.

Remove the solder first, then the iron, and let it cool without moving anything for a second. A good joint looks shiny and concave; a cold joint looks dull, rough, and blobby, and that is your sign to reheat and reflow it.

Here is the single idea that fixes everything for new solderers: heat the joint, not the solder. The instinct is to melt a blob on the iron and wipe it onto the connection, which produces a cold joint every time because the pad was never hot enough to bond. The solder must flow into a joint that is already hot enough to receive it. Practise on a cheap PCB kit at €5 to €15 until the joints come out consistently bright.

Benefits

Universal Electronics Repair Skill Opens All Electronics Projects Saves Cost on Device Repairs Gateway to Enthusiast Electronics Practical Science Understanding Fundamental Maker Skill

What you need

Here's what to gather before you start. The essentials are marked.

Some links below are affiliate links. As an Amazon Associate, trylii.com earns from qualifying purchases, at no extra cost to you.

Temperature controlled soldering iron

SuggestedAffiliate

Soldering iron

View on Amazon

Rosin core solder (60/40 or lead free)

Brass wool tip cleaner

Flux paste

PCB practice kit

Third hand tool

Fume extractor

FAQs

What temperature should I set the iron to?

320 to 350°C for most electronics with leaded solder, and 350 to 380°C for lead-free. Too cold and the solder won't flow, leaving weak cold joints. Too hot and you scorch flux and risk lifting pads off the board. A temperature-controlled iron holds its setting as you work, which is why it beats a cheap unregulated one for consistent results.

How do I know if a joint is actually good?

A good joint is shiny, smooth, and shaped like a tiny volcano, with a clean fillet flowing around the lead and pad. It looks like the solder wetted the metal rather than sitting on top in a ball. A dull, lumpy, or blobby joint means not enough heat or movement before it cooled. Good joints hold instantly. Bad ones fail later, often intermittently, which is maddening to diagnose.

Why won't the solder stick to anything?

Either the surface is dirty or the iron tip is oxidised. Solder needs clean, hot metal and active flux to bond. Tin the tip first: melt a little fresh solder onto it until it shines, then wipe it on a damp sponge or brass wool. If the tip looks black and dull, it has oxidised and won't transfer heat. Clean it or replace it before blaming yourself.

What's the difference between leaded and lead-free solder?

Leaded solder (63/37 tin-lead) melts lower, flows beautifully, and is far easier to learn on. Lead-free melts hotter, looks duller when set, and is fussier about temperature, but it avoids lead exposure entirely. Many beginners learn on leaded for the easier feel, then switch. Either way, wash your hands after handling solder and never eat at the bench.

Is the smoke dangerous?

The visible smoke is mostly burning flux, not lead, and you should not breathe it regularly. It irritates the airways and eyes. Work near an open window with a small fume extractor or a desk fan pulling the smoke away from your face. The lead risk comes from handling and ingestion, not the fumes, which is why hand-washing matters more than people expect.

⚠️ Solder fumes are burning flux and irritate the lungs. Always solder in a ventilated space with the smoke drawn away from your face, and wash your hands afterwards, especially with leaded solder.