Tip tinning, storage and end-of-day care
Most soldering failures blamed on technique are actually failures of the tip: an oxidised face transfers heat at a fraction of its rated rate, and the operator compensates by pressing harder and holding longer. Tip care is the cheapest quality improvement available.
Procedure
- 1
Wipe the tip on brass wool for two seconds to remove oxide without thermal shock.
- 2
Flood the face with Sn63Pb37 and RMA flux so the alloy covers the whole working area.
- 3
Wipe once more and check the face under 10x; it should be uniformly bright silver.
- 4
Leave a thin solder film on the face, park the tip in the stand, and switch the station off when the session ends.
- 5
Once a week, lower the setpoint to 250 degrees C and run the flux recovery routine on any tip showing dark patches.
Workshop notes
Why an oxidised tip lies to you
A clean, tinned chisel face wets the joint and transfers heat through a liquid metal bridge. An oxidised face - dark grey, matte, or black - has the thermal contact of a dry rough surface, typically 20 to 40% of the heat flow. The station still reads 340 degrees C because the thermocouple is inside the heater, not at the face. This is why the same joint that took two seconds yesterday takes five today.
Daily routine in four steps
Wipe on brass wool for two seconds, never on a wet sponge alone - the thermal shock of a wet sponge cracks the iron plating on plated tips. Re-tin with Sn63Pb37, which wets an oxidised face better than lead-free. Wipe again. Then set the tip down in a stand with a thin coating of solder left on the face, and turn the station off rather than leaving it idle at temperature. Idling at 340 degrees C for an hour oxidises a tip faster than a day of use.
Recovering a badly oxidised tip
If the face is black, do not scrape it with a file or abrasive - that removes the iron plating and the tip is finished. Instead, set the station to 250 degrees C (lower, not higher), flood the face with RMA flux and a large bead of Sn63Pb37, and let it sit for a minute. The activated flux reduces the oxide under the molten alloy. Wipe on brass wool and repeat up to three times. If the face does not turn bright silver, the plating is gone and the tip should be recycled.
Practice drill
Photograph the face of each tip on your bench once a week at 10x and keep the images in a folder. Tip degradation is slow and easy to miss day to day, but obvious across a month. Replace any tip whose face shows more than 30% dark area.
Failure modes
| Symptom | Cause | Treatment |
|---|---|---|
| Joint takes five seconds where it used to take two | Oxide layer on the tip face cutting heat flow to a fraction of rated value | Wipe on brass wool, flood with eutectic alloy and RMA flux, and verify the bright face at 10x before continuing |
| Tip plating flakes off in patches | Repeated wet-sponge thermal shock, or abrasive cleaning with a file or sandpaper | Switch to brass wool, never abrade, and retire the tip once the base metal shows |
| Solder refuses to stay on the face after tinning | Setpoint too high for the standby period, so the thin film oxidises within minutes | Enable sleep or set the station to 150 degrees C between joints, and re-tin after every ten joints rather than every fifty |
Supplies
- Sn63Pb37 solder wire for tinning
- RMA liquid flux
- Brass wool refills
- Distilled water (for the sponge, if used at all)
Tools
- Station with a calibrated setpoint
- 10x loupe
- Brass wool pot with a heavy base
- Spare tip set in each geometry you use
Safety
Brass wool holds fine metal fragments; empty the pot over a bin rather than over the bench, and never blow it out with compressed air. A tip left hot in a stand is the most common cause of a bench fire in a small workshop.
Neighbouring cards
- Dead-bug wiring a TSSOP 300 °C / 0.8 s
- Fixing tombstoned 0603 and 0805 parts 310 °C / 1.0 s
- Hand-placing a 0402 passive 320 °C / 1.0 s
- Two-iron removal of a 0805 chip 330 °C / 1.5 s