A soldering iron is used to join two metal parts by melting solder around them, most often to attach electronic components to a circuit board. Beyond electronics it is also used for repairs, wiring, jewellery making, stained glass, model making and many other hobby and trade jobs. This guide explains exactly what a soldering iron does, the full range of things it is used for, and how it works.
In one line
A soldering iron heats up to around 300 to 400°C and melts a metal alloy called solder, which cools to form a strong, permanent, electrically conductive bond between two parts. Its number one use is assembling and repairing electronics.
What Is a Soldering Iron?
A soldering iron is a hand tool with a heated metal tip, used to melt solder so it flows into a joint and bonds two metal surfaces together. When the solder cools and sets, it holds the parts mechanically and, crucially for electronics, conducts electricity between them.
Every soldering iron has the same basic parts:
- The tip is the working end that transfers heat to the joint. Tips come in different shapes (chisel, conical, bevel) for different jobs and are a wear item you replace over time.
- The heating element sits behind the tip and brings it up to temperature, see soldering iron heating elements and parts.
- The handle stays cool so you can hold it safely.
- A stand holds the hot iron safely between joints, usually with a sponge or brass wool to clean the tip.
A simple plug-in iron runs at one fixed heat. A soldering station adds a temperature dial and electronic control so you can set an exact temperature for the job, which is why stations are preferred for electronics.
What Is a Soldering Iron Used For?
A soldering iron is used anywhere two metal parts need a permanent, conductive or sealed join that is too small or too delicate for welding. The most common uses are:
- Electronics assembly. Soldering components (resistors, chips, connectors, LEDs) onto printed circuit boards. This is by far the most common use.
- Electronics repair. Fixing phones, laptops, games consoles, TVs and appliances by replacing failed parts, reflowing joints and reattaching connectors.
- Hobby and maker projects. Building Arduino, Raspberry Pi and robotics projects, plus solder-together electronics kits for learning.
- Joining and extending wires. Making solid electrical connections between wires and onto terminals, switches and plugs.
- Automotive and appliance work. Repairing wiring looms, sensors and small electronic modules.
- Jewellery making. Joining findings and small metal pieces (using the right solder for the metal).
- Stained glass. Running solder along the copper foil or lead came that holds the glass pieces together.
- Model making and RC. Wiring motors, speed controllers and battery connectors in models, drones and remote-control vehicles.
- Guitars and music electronics. Wiring pickups, pots and jacks in guitars, pedals and amps.
- Pyrography and plastic work. With a specialist tip, some irons are used for wood burning or for welding and repairing plastics, though dedicated tools do these jobs better.
Not for plumbing pipes
An electronics soldering iron is not the right tool for copper plumbing pipes, that job uses a blowtorch and acid-core plumbing solder. Never use acid-core or plumbing solder on electronics, it corrodes the tracks. Electronics soldering uses rosin-core solder, see our soldering wire range.
Uses of a Soldering Iron in Electronics
Electronics is where a soldering iron earns its keep. Inside almost every device you own, the components are held to the circuit board by soldered joints. A soldering iron lets you:
- Assemble new boards, soldering through-hole and surface-mount (SMD) components onto a PCB.
- Replace a failed component, such as a blown capacitor, burnt resistor or dead connector, by desoldering the old part and soldering in a new one.
- Repair broken joints, reflowing a cracked or “dry” joint that has stopped conducting.
- Reattach connectors and ports, a very common phone and laptop repair where a charging port has torn loose.
- Modify and prototype, adding wires, headers and parts when building or hacking a circuit.
Because electronic parts are heat-sensitive and the joints are tiny, electronics soldering needs controlled temperature and a fine tip. That is why a temperature-controlled station is the right tool here, see best soldering iron for electronics and how to choose a soldering station.
How a Soldering Iron Works (and What Temperature to Use)
The principle is simple: the heated tip warms both metal parts of the joint, then solder is touched to the joint (not the tip) so it melts, flows around the parts and is drawn into the gap. Remove the heat and within a second or two the solder freezes into a solid, conductive bond.
The flux inside the solder wire is what makes it flow. Flux cleans the metal as it heats so the molten solder can “wet” the surface and stick. This is why you should never sand or scrape a joint, just let the cored flux do the work.
Soldering temperature guide
| Job | Typical tip temperature |
|---|---|
| Heat-sensitive parts, fine SMD | 280 to 320°C |
| General electronics, leaded solder | 330 to 350°C |
| Lead-free solder | 350 to 400°C |
| Large joints, ground planes, thick wire | 380 to 410°C |
Start at the lower end and raise the temperature only if the solder is not flowing. Hotter is not better, excess heat damages parts and wears the tip faster.
What Can You Solder With a Soldering Iron?
Soldering works on metals that the solder can wet and bond to. With standard electronics solder you can join:
- Copper (PCB pads, wires, copper foil), the easiest and most common.
- Tin-plated and pre-tinned metals, component legs, pins and terminals.
- Brass and bronze, common in connectors and some jewellery.
- Steel, with the right flux, though it is harder to wet.
Some metals are difficult or need special solder and flux: aluminium and stainless steel resist normal solder, and you cannot solder to iron, chrome or oily/dirty surfaces without preparation. Soldering also does not join plastics or non-metals.
For a strong joint you need clean metal, the right solder, and enough heat, the three things most beginner problems come down to.
Soldering Iron vs Soldering Gun vs Soldering Station
People often mix these up. They all melt solder, but they suit different jobs:
| Tool | Best for | Notes |
|---|---|---|
| Soldering iron (pencil) | Electronics, hobby, fine work | Light, precise, low power. The everyday choice. |
| Soldering station | Electronics, regular use | An iron plus temperature control and a stand. Best for electronics. |
| Soldering gun | Heavy wires, repairs, occasional use | Pistol shape, high power, heats fast but too hot and clumsy for delicate boards. |
For electronics, a pencil iron or a station is almost always the right answer. A gun is for heavier, occasional jobs. The difference between a plain iron and a temperature-controlled station is covered in soldering station vs soldering iron and how to choose a soldering station.
What You Need to Start Soldering
To put a soldering iron to use you need just a few things:
- A temperature-controlled iron or station. For electronics, a controlled iron such as the YIHUA 937D+ is a popular first choice. See best soldering station for beginners if you are still choosing.
- Solder wire. 0.8mm leaded 63/37 is the easiest to learn on, see soldering wire.
- A clean tip and tip cleaner, plus a stand to park the hot iron safely.
- Basic safety, a ventilated space and ideally a fume extractor, since the flux smoke is an irritant.
From there it is practice. A cheap solder-practice kit is the best way to build clean-joint skills before working on anything that matters.
Watch: What a Soldering Iron Is Used For
A short visual walkthrough of how a soldering iron is used and what a good joint looks like:
Frequently Asked Questions
What is a soldering iron used for?
A soldering iron is used to join metal parts by melting solder around them. Its most common use is attaching and repairing electronic components on circuit boards, but it is also used for wiring, jewellery, stained glass, model making and many other hobby and repair jobs.
What does a soldering iron do?
It heats up to around 300 to 400°C and melts solder, a metal alloy, which flows into a joint and then cools to form a permanent, electrically conductive bond between two parts.
What is the main use of a soldering iron in electronics?
Assembling and repairing circuit boards: soldering components onto a PCB, replacing failed parts, fixing cracked joints, and reattaching connectors such as phone charging ports.
What can you solder with a soldering iron?
Mostly copper, tinned metals, component legs, brass and (with the right flux) steel. Aluminium and stainless steel need special solder, and you cannot solder plastics or non-metals.
Is a soldering iron the same as a soldering gun?
No. A soldering iron is a light, precise pencil-shaped tool for electronics and fine work. A soldering gun is a high-power, pistol-shaped tool better suited to heavy wires and occasional jobs, but too hot and bulky for delicate boards.
Can I use a soldering iron for plumbing?
No. Plumbing pipes need a blowtorch and acid-core plumbing solder. An electronics soldering iron does not get a copper pipe hot enough, and plumbing solder must never be used on electronics because it corrodes the tracks.
What temperature should a soldering iron be?
Around 330 to 350°C for general electronics with leaded solder, 350 to 400°C for lead-free, and 280 to 320°C for very heat-sensitive parts. Start lower and increase only if the solder will not flow.