Using and maintaining lower end soldering iron tips without destroying them

Question

I bought a low end soldering iron of eBay - it was advertised as a "15 in 1 Soldering Iron Kit", and was advertised as temperature adjustable. It has a dial to adjust the temperature with numbers in degrees Celsius.

I put a new chisel tip from the kit in it, turned it up to 350 degrees Celsius, tinned the iron, and successfully soldered a couple of joints with lead-free electronics flux-core solder. Then I cleaned it on the damp sponge that came with the kit, and waited for it to heat to a temperature where it would melt the solder again. But by the time it reached that temperature, it had already gone black and the solder just balled and rolled off the tip. Wiping it on the sponge again cooled it, and the same problem was there when it heated back up.

I tried adding no-clean electronics flux from a flux pen to some balls of solder, and melted them into a blob, and it stuck to a tiny part of the tip. I tried letting the tip sit in the ball for a little while, and it still kept rolling off and not tinning. I wiped it on the damp sponge again, and repeated the flux treatment a couple of times, but the tip has developed some kind of yellow mineral-like crusty coating that isn't coming off with the sponge or the flux (and I'm wondering if it is possibly even from the sponge) - and now I can also see a reddish colour that I think might be the copper core.

This is a magnified view of what the tip looks like now (it is cool - red is not glowing metal):

I'm assuming that this one day old tip is completely wrecked now? It was a cheap iron / tip, but I'm getting a more expensive soldering station soon, and I want to make sure I don't ruin the tips the same way. I never used the soldering iron above 350 degrees Celsius, I had the tip on the iron while it was on for less than an hour total, I never scratched it on anything or used much pressure, and I don't think it was exposed to any contaminant (unless it was the flux), and I tried to keep it tinned as soon as it reached a temperature where that was possible - what else could I be doing wrong? Or is it just that the cheap iron is reaching temperatures that are higher than my selection (it does only have two wires from the PCB inside it to the element, despite being sold as temperature adjustable - so I assume it doesn't have a true thermostat and only adjusts the power / current / voltage based on the dial)? Or is it a poor quality tip that was always going to fail after a use or two?

Answer 1

The iron you have uses really low quality tips - about like the ones on the cheap irons I had as a kid.

The black stuff is burned flux. Your iron is too hot. 350 C is more than you should need for normal 60/40 tin/lead solder. 270 C should be more than enough.

I think you have a combination of "set the dial too high" and "the dial is horribly inaccurate." You set it too high, then the regulator lets it get even hotter than what you set it to.

• Use 60/40 tin/lead solder that has a rosin core. You shouldn't need extra flux for anything you can reasonably do with that iron.
• Lower the temperature. I'm normally a proponent of "solder hot, work fast," but there's "top end of recommended temperature range" and there's "over the top, too hot, just burning stuff." You are in that second range.
• "Damp sponge" means "damp," not "wet." It shouldn't make the temperature of the iron drop much at all. Soak the sponge so it is wet all the way through. Squeeze it out, wring it until you think it is dry. That's damp enough for use.

The tip as you show it will be difficult to use. You'll have to clean it up and re-tin it.

It originally had a thin coat of iron on it. That is gone, and you can't really replace it.

I never noticed the iron plating do any good on the cheap tips. It's damaged now, and partially gone - the red stuff you see is the copper core of the tip.

• File the tip smooth. Remove the black gunk and the silvery colored iron plating. Clean the tip to about 8mm from the point - you want about 8 to 10 mm of bare copper from the tip.
• Set the temperature to maybe 250 C (270 is what you want, but start low because your iron is probably hotter than the dial says.)
• Once it is hot, take your 60/40 tin/lead solder with rosin core and rub it up and down the bare copper. Get it to melt and flow on the tip. Rotate the iron so you get solder all around the tip.
• Tin the whole area you cleaned up - cover all of the bare copper with solder.

Once you have that done, you can use the iron to solder again.

You'll probably have to repeat that process every few hours. The tip is copper, and it dissolves in the solder. The tip will get pits and holes in it. Clean it up, file it smooth, re-tin it as needed.

• Use only 60/40 tin/lead solder with a rosin core.
• Do not use "no clean flux" on it.
• Do not use plumber's flux or acid core solder.
• Do not use lead free solder on it. Lead free usually requires a higher temperature, and it also "eats" copper faster.

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A trick I learned long ago was to file the tips clean and smooth, then hammer them into shape.

Hammered copper hardens, and lasts longer in the soldering iron. Not "days longer," but hours - which is still better than the plain copper tip.

Alternatively, look into buying a better iron with decent tips. Anything that takes a standard Hakko or Weller tip will be better than the iron you have - and the tips will be better quality.

There are some tips on my blog about how to use a soldering iron. I photographed most of the examples while using an iron not much better than the one you have.

I spent literally years working with a good soldering iron. The blog posts were written at home using a crummy iron because that's what I had at home.

It doesn't take a super duper expensive iron, though you may have to put up with things like making or reforming the tips for a cheap iron.

Answer 2

That is exceptionally bad. It is not normal for a tip to be destroyed after a single use on 350 degC. Even a single use on ~420degC and probably even a bit higher should not immediately damage the tip.

My guess is that the temperature indicator is lying - your tip is much hotter than indicated.

Answer 3

That's a very good photo!

it does only have two wires from the PCB inside it to the element, despite being sold as temperature adjustable - so I assume it doesn't have a true thermostat and only adjusts the power / current / voltage based on the dial

The heater is a resistor that grows in resistance with increased temperature – so, this really is probably at least roughly temperature-controlled. The tip+heater is the thermostat!

It's not going to be phantastically accurate, but it actually is a common control method.

I'm assuming that this one day old tip is completely wrecked now

Seeing that there's plenty of copper (the red metal), nah, this isn't wrecked. It might need some... work.

However, I'm confused where the black slag with the white coat comes from – if this was actually electronics solder, then it wouldn't be doing this to the copper surface. Maybe it's burnt flux, but you wiped of the tip.

You said you needed to wait after wiping off the tip – I mean, sure, that cools down the tip, but the wiping I do usually last for about half a second of tip-sponge contact on each side (I honestly rarely wipe at all). So maybe you really wiped it off for seconds and that led to scale building up?

I'm willing to blame the sponge here, maybe the black stuff is burnt sponge?

No matter what: If the black slag used to be the factory tinning, it's definitely gone. Either way, you'll have to remove that, scrub it carefully until the tip shines in a coppery silver-red (not the dull red of oxidized copper), directly apply flux, heat the tip to much lower temperature (say, 230 °C, the flux shouldn't start to smoke) and carefully start re-tinning the tip.

Try with different, fresh solder, instead of some solder balls + flux. Make sure your flux is really electronics flux with low/no acid content.

Answer 4

In addition to the other comments and answers:

IME, Cleaning it with something abrasive will wear away the plating, causing a good tip to go bad faster. However, after the plating is already gone, then abrasives will actually return a fouled-up tip to a relatively useful condition -- but it will only last a short time.