Guide · Tips and cartridges
Why solder won't stick to the tip
Solder beading off the tip points to oxide, a lost coat of solder or worn plating. How to tell which, how to recover the tip, and when to replace it.
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Short answer
Solder only sticks to clean, hot metal. If it beads up and rolls off, look first for oxide on the tip: wipe it, then feed fresh flux-cored solder straight onto the working face. If the tip is badly blackened, tip-tinning paste can usually recondition it, according to Adafruit.[1] If the plating is pitted or worn through, replace the tip. Never file or sand it.
Match the symptom to the cause
| What you see | Likely cause | What to do |
|---|---|---|
| The tip looks dull, gray or black, and solder balls up and rolls off | A layer of oxide on the tip | Wipe, then tin at once with flux-cored solder; use tip-tinning paste if that fails |
| Solder sticks at first, then stops after the iron sits idle | The coat of solder burned off while idle | Re-tin before each joint, and leave a coat on before you park the iron |
| Solder melts slowly or stays lumpy on the tip | The setting is too low for the alloy | Check the alloy and the setting (see below) |
| A pit, a crater or a worn-down end, and no amount of tinning helps | The plating is worn through | Replace the tip or cartridge |
| Solder coats the tip but will not flow onto the pad | The joint, not the tip | Add flux and heat the pad and the lead together |
Why tips stop taking solder
Wetting needs bare, clean metal. A hot tip reacts with the air and grows a skin of oxide, and molten solder will not wet that skin. Flux strips oxide away, which is why a feed of fresh flux-cored solder can bring a dull tip back.
A coat of solder protects the working face. A tip left hot and bare has nothing protecting it, and a tip you have just wiped clean stays bare until you tin it again.
Plating is the other half of the story. Soldering tips are plated, and once the plating is scraped or worn through, the tip will not hold solder however you treat it. Adafruit warns that files and abrasives damage the plating and ruin the tip.[1]
How to recover an oxidized tip
- Set a normal working temperature, not the maximum. SparkFun teaches beginners at 325–375 °C.[2]
- Wipe the tip on the station's cleaner, brass wool or a damp sponge.
- Tin it at once. Touch flux-cored solder to the working face. If it wets, add a little more and wipe off the excess, leaving the thin, shiny coat Adafruit describes.[1]
- If solder still beads, work the tip in tip-tinning paste, then tin again. Adafruit says a badly oxidized tip can usually be reconditioned this way.[1]
- Repeat a few times. A tip that takes solder across its whole working face is back in service.
- Replace the tip if no part of the working face will take solder. Do not sand or file it to expose fresh metal.
Is it the temperature?
Sometimes. Lead-free solder needs more heat: SAC305 melts at 217–220 °C, against 183 °C for 63/37 tin-lead.[3] Adafruit suggests about 400 °C for lead-free and 370 °C for 60/40 on a temperature-controlled iron.[1]
More heat is not a general cure, though. Kester recommends about 400 °C (750 °F) for its rosin-flux wires and 315–345 °C (600–650 °F) for its no-clean wires.[4] If the tip still will not tin at your solder maker's recommended setting, look at the tip rather than the dial.
Replacing a cartridge tip
On a cartridge station, the tip is not a separate sleeve. Hakko describes its T12 cartridge as a tip integrated with the heating element and sensor,[5] so a worn T12-format tip means a new cartridge. Replace like with like: the same tip system, and the shape you actually use. The tip shape guide helps if you are unsure which shape to reorder.
Keep it from happening again
- Tin before each joint, as SparkFun recommends, and leave a coat of solder on the tip before you park it.[2]
- Wipe, then tin. Never park a freshly wiped, bare tip.
- Use sleep or standby if your station has it. JBC says the sleep and hibernation modes on its stations extend tip life up to five times.[6] That is the maker's claim about its own equipment, without a published test method.
- Do not run hotter than the job needs. Start from your solder maker's recommendation.
Next
Questions
Should I sand or file a soldering tip that won't tin?
No. Adafruit warns that files and abrasives damage the plating and ruin the tip. Use tip-tinning paste instead, which Adafruit says can usually recondition a badly oxidized tip.[1]
Why did my new soldering tip turn black so quickly?
A tip left hot without a coat of solder has nothing protecting it. Tin a new tip as soon as it first reaches temperature, re-tin before each joint as SparkFun recommends, and never park it freshly wiped and bare.[2]
Will a higher temperature help solder stick to the tip?
Only if the setting is too low for your alloy. Adafruit suggests about 400 °C for lead-free and 370 °C for 60/40. Above your solder maker's recommendation, more heat does not fix an oxidized or worn tip.[1]
How do I know a tip is beyond saving?
When the plating is pitted or worn through and no part of the working face will take solder, even after tip-tinning paste. On a cartridge system you then replace the whole cartridge, since Hakko builds the heater and sensor into its T12 tip.[5]
Solder sticks to my tip but not to the pad. Is the tip the problem?
Probably not. SparkFun recommends heating the pad and the part together, and its fix for heavy joints is a larger tip, more flux and a little more time. See why ground planes are hard to solder.[2][9]