HOW-TO GUIDE
Soldering Iron Temperature by Metal
By the OhmSavvy Research Team ·
The two variables: solder alloy and thermal mass
"What temperature should my iron be?" actually depends on two separate things. First, the solder alloy itself has a melting point the tip needs to clear with some margin — leaded solders melt lower than lead-free ones. Second, the joint's thermal mass (how much surrounding metal is pulling heat away) determines how much hotter than the melting point the tip needs to run, and how long you need to hold it there, to actually bring the joint itself up to temperature rather than just the solder touching the tip.
Setpoint by solder alloy
Iron temperature needs to clear the solder's melting point with enough margin to melt it quickly rather than slowly — running only a few degrees above the melting point means weak, slow heat transfer into the joint.
See our 60/40 vs 63/37 comparison for the exact melting ranges behind the leaded-solder figures above.
Setpoint by joint or metal type
| Joint / metal type | Typical adjustment | Why |
|---|---|---|
| Fine SMD pads, thin signal wire | Lower end of range, smaller tip | Low thermal mass; too much heat risks lifting a pad or damaging the part |
| Standard through-hole components | Middle of range | Balances reliable melting with component safety margin |
| Ground planes, large copper pours | Higher end of range, or larger tip | High thermal mass draws heat away quickly; needs more heat supplied, faster |
| Thick wire, chassis grounds, connectors | Higher end of range, larger tip, longer dwell | Large metal mass needs sustained heat delivery to come up to temperature |
Base metals: copper, brass, nickel, steel, aluminum
The metal being joined matters too, mainly through how well solder wets it and how fast it conducts heat away. Copper and tinned copper wet easily but conduct heat very well, so heavy copper needs a larger tip rather than a dramatically hotter one. Brass wets well with ordinary rosin flux once it is clean. Nickel-plated battery tabs and connector shells wet more slowly and often need extra flux. Steel conducts heat poorly, so it is easy to heat locally, but plain and stainless steel usually need an aggressive acid-type flux that must never be used on electronics. Aluminum forms a tough oxide layer that ordinary solder and flux won't break through; it needs a dedicated aluminum solder and flux system.
| Base metal | Wettability with rosin flux | Setting approach |
|---|---|---|
| Copper / tinned copper | Excellent | Normal setpoint; size the tip to the copper mass |
| Brass | Good once cleaned | Normal to upper setpoint; brass terminals are often bulky |
| Nickel-plated tabs | Fair; needs extra flux | Upper setpoint with a broad tip and short dwell |
| Plain / stainless steel | Poor; needs acid flux | Not for electronics work; follow the flux maker's guidance |
| Aluminum | Very poor with standard solder | Special aluminum solder and flux only |
Why thermal mass changes the picture
The same tip, at the same setpoint, delivers heat into very different surroundings depending on the joint. A small, isolated pad has almost nowhere for that heat to escape to, so it comes up to temperature quickly. A pad connected to a wide copper pour or ground plane has a huge amount of surrounding metal pulling heat away in every direction, so the same tip at the same temperature takes noticeably longer to bring that specific joint up to melting point.
Why hotter isn't simply better
Signs your temperature setting needs adjusting
Rather than guessing a number, watch for these signs during normal soldering:
| What you're seeing | Likely adjustment |
|---|---|
| Solder takes 3+ seconds to melt on a normal joint | Raise the temperature, or check for a dirty tip first |
| Flux is smoking heavily or scorching dark before solder flows | Lower the temperature |
| Joints cool and solidify oddly slowly after the iron is removed | Temperature may be too high; excess heat soaked into the board |
| Large joints never fully melt despite a high setting | Switch to a larger tip or higher-wattage iron rather than raising temperature further |
Preheating for extreme thermal mass
Quick reference: where to start
- General through-hole electronics, leaded solder: 300–330°C
- Fine SMD work, leaded solder: 280–310°C with a fine tip
- Lead-free solder, general work: 340–370°C
- Large ground planes or thick wire: upper end of range, plus a larger tip and longer dwell
These are reasonable starting points, not fixed rules — adjust based on what you actually see at the joint, as covered above.
1Start at the alloy's typical setpoint
Pick the starting figure from the chart above for your solder: around 300–330°C for leaded alloys and 340–370°C for lead-free. Let the station settle on that number before you judge anything.
2Time a test joint
On a clean, freshly tinned tip, solder one representative joint and count. Wetting within about one to three seconds means the setting suits that joint. Much longer means too little heat is reaching it; much quicker, with flux smoking hard, suggests you can come down.
3Change the tip before the temperature
If a heavy joint is slow, fit a broader tip and retest at the same setting. Raise the temperature in small steps of about 10–20°C only if a bigger tip isn't practical, and drop it back when you return to small joints.
Heat and fume safety
Irons with an adjustable setpoint
Everything on this page assumes you can set and trust a number. A fixed-wattage iron has no setpoint at all, so its tip simply settles wherever heat in balances heat out. These picks from our reviews all offer closed-loop control, and they cover the full range from fine leaded work to heavy lead-free joints.
Temperature-controlled irons from our reviews
50–480°C with five presets per Hakko, so leaded, lead-free and heavy-joint settings can each be saved.
PID station, 200–480°C with ±2°C static stability and a C/F switch, ESD safe.
67W with a 240–540°C dial for thick wire, terminals and other heavy metal; too warm at minimum for fine SMD.
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Frequently asked questions
What temperature should I start at if I'm not sure?
Around 300-330°C (570-630°F) for leaded solder on typical through-hole electronics work is a reasonable, widely-used starting point. Adjust upward if solder is melting slowly or joints are taking more than two to three seconds to wet, and downward if you're seeing scorched flux or damaged components.
Does wire gauge affect the right temperature setting?
It affects how long you need to hold the joint at temperature more than the setpoint itself. Thicker wire has more thermal mass and pulls heat away from the tip faster, so it benefits from either a slightly higher setpoint, a larger tip for better contact area, or simply a touch more dwell time — not a fundamentally different temperature range.
Can I just leave my iron at one temperature for everything?
For a lot of general hobby work, yes — many hobbyists pick one setpoint in the 300-350°C range for leaded solder and rarely change it. Where it matters is at the extremes: very fine SMD work benefits from a slightly lower, more controlled setting, and large ground-plane joints benefit from going higher or switching to a bigger tip rather than fighting a joint that won't heat through.
Is it true that a lower temperature is always gentler on components?
Not quite — a temperature too low for the joint often means holding the iron there much longer to compensate, and that extended dwell time can do more heat damage to a component than a correctly higher setting applied briefly. Matching temperature to the joint, rather than always running cool, usually protects components better.
What temperature is 350°C in Fahrenheit, and which unit should I set?
350°C is 662°F, using °F = °C × 9 ÷ 5 + 32. Likewise 300°C is 572°F and 370°C is 698°F. Use whichever unit your station displays, but stick to one: most solder datasheets and tutorials quote Celsius, so many people switch their station to °C to avoid converting every figure they read.
