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Choosing a new soldering iron...
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Re: Choosing a new soldering iron...

by sirket on Thu May 20, 2010 5:11 pm

mojo wrote:PS. Using a brass sponge to clean the tip instead of a wet sponge makes them last 20x as long and perform consistently throughout their lifetime, as well as doing a better job of actually cleaning them. Wet sponges also cool the tip a little.

Wet sponges and brass pads serve different purposes. Brass pads are used to remove excess solder and larger contaminants from your tip. A wet sponge (actually damp- not wet) is used to remove smaller contaminants and chemicals like flux which, especially in the case of an RA flux, can definitely eat up your tip. You should use the wet sponge any time you think the brass pad is not properly cleaning the tip. As soon as you use the wet sponge you should tin your tip. If it is the last cleaning of the day then you should use tip tinner and not solder as it does not contain flux which can corrode a tip.

A wet sponge should not cause any degradation in your tip if you use distilled water (or other source of very clean water). You should wash your sponge from time to time to remove any chemicals like fluxes that can build up.

The temperature drop from using a sponge is negligible for a good iron- the recovery time is so fast that by the time you're a couple of inches from the sponge, the tip has completely recovered. Don't use cold water, or let the sponge get too wet. Doing so can cause the temperature to drop more than necessary, and can even cause thermal shock that damages the tip.
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Re: Choosing a new soldering iron...

by mojo on Thu May 20, 2010 6:50 pm

Interesting argument sirket. I'm not quite following you though - you say use distilled water but that it should not be cold. What are we talking here? Room temperature is still >400C lower than the tip temperature typically is so will still cause thermal shock. Saying that, even at 99C, the absolute maximum, it is still going to fatigue the tip.

I have found my tips last much longer since I switched to brass. I use my iron almost every day and a single tip lasts for years (about 2 years on the current one and it's still as good as it ever was). Occasionally I use a little bit of tip cleaner, but usually I do nothing more than wipe on/in the brass sponge.

A well made tip should last a long time with a bit of basic care I think. You really don't have to spend a lot or do anything special IME.
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Re: Choosing a new soldering iron...

by sirket on Thu May 20, 2010 7:31 pm

mojo wrote:Interesting argument sirket. I'm not quite following you though - you say use distilled water but that it should not be cold. What are we talking here? Room temperature is still >400C lower than the tip temperature typically is so will still cause thermal shock. Saying that, even at 99C, the absolute maximum, it is still going to fatigue the tip.

Thermal shock is caused be a rapid loss of heat. Using the warmest water possible, and keeping the sponge as dry as possible, minimizes the amount of heat that can be removed from the tip and that minimizes shock. Try throwing one tip into a bath of ice water (a very cold, soaking wet sponge)- then lightly brush another against a room temperature, barely wet sponge. Now tell me it has the same thermal effect. It does not.

I have found my tips last much longer since I switched to brass.

Again- different purposes. I always have both brass and a damp sponge on my desk- and they do not clean in the same manner. You don't need both- but there are situations in which both can be helpful. Weller includes sponges with their irons because it is the most effective means of removing chemicals, as well as solder and other contaminants, from the tip.

I use my iron almost every day and a single tip lasts for years (about 2 years on the current one and it's still as good as it ever was). Occasionally I use a little bit of tip cleaner, but usually I do nothing more than wipe on/in the brass sponge.

What kind of flux do you use? My guess would be a water based flux or an RMA flux. If you use stronger fluxes then believe me- you want to clean your tip with a sponge. If you're going to put your tip away for an extended period of time- then believe me, you want to clean your tip with a sponge.

When I bought my rework station I purchased a number of tips along with spares for each one. To this day (4 years later) I'm still using the same tip I started with- only occasionally swapping it out for a more specialized tip when necessary. Using a sponge has done nothing to harm the tip and I also use my iron nearly every day.

In your case you said that your tips last 20 times longer since you stopped using sponges. If your current tip has lasted 2 years then does that mean that you were only getting 1 month out of a tip before?
Last edited by sirket on Thu May 20, 2010 7:52 pm, edited 1 time in total.
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Re: Choosing a new soldering iron...

by sirket on Thu May 20, 2010 7:48 pm

mojo wrote:Interesting argument sirket. I'm not quite following you though - you say use distilled water but that it should not be cold. What are we talking here? Room temperature is still >400C lower than the tip temperature typically is so will still cause thermal shock. Saying that, even at 99C, the absolute maximum, it is still going to fatigue the tip.

In fact, you seem to be suggesting that liquid fluxes would also destroy a tip- as they are essentially water applied directly to the tip. That's obviously not the case though- a lot of people, myself included, use liquid fluxes with no ill effect.
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Re: Choosing a new soldering iron...

by mojo on Thu May 20, 2010 7:58 pm

sirket wrote:Again- different purposes. I always have both brass and a damp sponge on my desk- and they do not clean in the same manner. You don't need either one- but there are situations in which both can be helpful. Weller includes sponges with their irons because it is the most effective means of removing chemicals, as well as solder and other contaminants, from the tip.


What exactly are you doing with your iron that gets all this nasty stuff on it? I only use mine for soldering electronics with various types of lead and lead free solder and only ever use brass or very occasionally tip cleaner on it and there is no build of up anything and no loss of performance. In fact about the only thing that really does have much impact on my tips is a wet sponge, but then again maybe I'm not working with the kind of hazardous stuff you are.

What kind of flux do you use?


Usually none. I use two types of solder which include a small amount of flux.

For small surface mount ICs I use a basic flux pen dispensing "no clean" flux. I tried brush applicators and a couple of different fluxes but the gains didn't seem to outweigh the use of nasty chemicals and the clean-up required. I have banned in my hands anyway so TQFP is about as small as I go the pen is more than adequate for it.

about 2 years on the current one and it's still as good as it ever was
In your case you said that your tips last 20 times longer since you stopped using sponges. If your current tip has lasted 2 years then does that mean that you were only getting 1 month out of a tip before?


No, it means that my current tip is "about 2 years [old] and it's still as good as it ever was". 20x may have been an exaggeration, ask me again in another 38 years.
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Re: Choosing a new soldering iron...

by mojo on Thu May 20, 2010 8:08 pm

sirket wrote:In fact, you seem to be suggesting that liquid fluxes would also destroy a tip- as they are essentially water applied directly to the tip.


Nope, you are mistaken. Try not to assume more than I actually wrote.

You suggested using warm water instead of cold water. My point was that warm water is only a few tens of degrees higher than cold water, which considering that irons typically work at around 480C is pretty much neither here no there. If, as I believe, a damp sponge causes more fatigue to a tip than a brass sponge then the temperature of the water is going to make little difference.

Just think about what you are saying for a moment. The iron touches cold objects all the time - heating them up is its purpose. The key is the type of material of liquid in question, not a few tens of degrees.
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Re: Choosing a new soldering iron...

by sirket on Thu May 20, 2010 8:26 pm

mojo wrote:What exactly are you doing with your iron that gets all this nasty stuff on it? I only use mine for soldering electronics with various types of lead and lead free solder and only ever use brass or very occasionally tip cleaner on it and there is no build of up anything and no loss of performance.

I occasionally do rework on old, dirty, corroded connections- and RA flux helps clean everything up. It also pits your iron if you leave it on the tip. I don't use RA flux often, but it's in my tool box along with RMA and no clean water based fluxes- all from Kester. I also occasionally solder small brass miniatures- but never with my good rework station and those are done with acid fluxes.

In fact about the only thing that really does have much impact on my tips is a wet sponge, but then again maybe I'm not working with the kind of hazardous stuff you are.

You are either using a sponge that's way too wet, or you're getting very poor quality tips, or both. In my personal experience, and seemingly that of most people on the Internet, there is no harm in using a damp sponge. There is also no good scientific reason either- as I said- a liquid flux would likely cause a larger heat drop than a damp sponge and no one complains about them.

Usually none. I use two types of solder which include a small amount of flux. For small surface mount ICs I use a basic flux pen dispensing "no clean" flux. I tried brush applicators and a couple of different fluxes but the gains didn't seem to outweigh the use of nasty chemicals and the clean-up required. I have banned in my hands anyway so TQFP is about as small as I go the pen is more than adequate for it.

You are very lucky. As I said- I sometimes have to do rework on old components and a good strong flux leaves the surface usable. For new work a strong flux is overkill.

No, it means that my current tip is "about 2 years [old] and it's still as good as it ever was". 20x may have been an exaggeration, ask me again in another 38 years.

Fair enough.

In the end there are two methods of cleaning an iron and they serve different but overlapping purposes. They both have their place- but if you had to choose 1- the sponge covers more scenarios.

NASA has always trained people to use a sponge and I'm willing to follow their lead.
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Re: Choosing a new soldering iron...

by sirket on Thu May 20, 2010 8:32 pm

mojo wrote:You suggested using warm water instead of cold water. My point was that warm water is only a few tens of degrees higher than cold water, which considering that irons typically work at around 480C is pretty much neither here no there. If, as I believe, a damp sponge causes more fatigue to a tip than a brass sponge then the temperature of the water is going to make little difference.

In that case feel free to use ice water- be my guest. There is simply _no_ reason to make possible thermal shock worse by using colder water. Using warm water has no down side and could help avoid a problem for a tip that is on the edge already. You seem fixated on a side remark I made about water temperature but have no problem making exaggerated claims about tip life when that suits your argument.

Just think about what you are saying for a moment. The iron touches cold objects all the time - heating them up is its purpose. The key is the type of material of liquid in question, not a few tens of degrees.

So water in a sponge is somehow more fatiguing than water in a flux? I think it's you that need's to stop and think about what you're saying for a moment. How is a water based flux any different than water in a sponge? Hint: It's not.
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Re: Choosing a new soldering iron...

by adafruit_support_bill on Thu May 20, 2010 8:57 pm

Gentlemen:

Let's keep this civilized. There is some good technical information in this thread. It would be a shame to have to lock it.

Arduwino - (Moderator)

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Re: Choosing a new soldering iron...

by sirket on Thu May 20, 2010 9:07 pm

arduwino wrote:Let's keep this civilized. There is some good technical information in this thread. It would be a shame to have to lock it.

Fair enough.

Both brass wool and a damp sponge are excellent ways to clean a soldering iron. I own a Weller WRS7000x (a $4,500 soldering station) and have been using both methods for years. Neither one will hurt your soldering iron.

Brass wool doesn't drop the temperature and is rough enough to remove stubborn surface contaminants in addition to solder. It's an excellent choice for use when doing a lot of solder joints quickly.

A sponge will remove chemicals from your tip, in addition to solder and surface contaminants. It can drop the temperature slightly- but it's a better choice when using activated fluxes (i.e. not "no clean" fluxes) and before putting your iron away for a while.
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Re: Choosing a new soldering iron...

by charliex on Thu May 20, 2010 9:46 pm

I love my metcal and I got a great deal off eBay , dozens of spare tips and a set of talons. Its the older model, but its still fantastic. It heats up so fast, nice auto off feature and i can switch between either two irons or iron and talons in a jiffy. Plus i really like how the tip temperature is set by the bit, no need to worry about it at all.
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Re: Choosing a new soldering iron...

by mojo on Fri May 21, 2010 1:41 pm

sirket wrote:I occasionally do rework on old, dirty, corroded connections- and RA flux helps clean everything up. It also pits your iron if you leave it on the tip. I don't use RA flux often, but it's in my tool box along with RMA and no clean water based fluxes- all from Kester. I also occasionally solder small brass miniatures- but never with my good rework station and those are done with acid fluxes.


Sounds nasty! I have an old 30W iron from a DIY shop that I used a couple of times on old audio gear with really bad corrosion, but all I did was remove the old solder and replace it. We get quite a few PCBs that have had liquid spilt on them at work (Coke is the worst) but we usually clean them up completely with an ultrasonic bath and then IPA before doing any soldering or hot air reworking.

I thought that was bad enough but now I feel lucky I don't have to deal with the nasty stuff you do ;-)

You are very lucky. As I said- I sometimes have to do rework on old components and a good strong flux leaves the surface usable. For new work a strong flux is overkill.


The OP was asking about an iron for hobby use and I can't see most hobbyists needing anything like that. I have worked on old audio gear as well as home and arcade game gear from the late 70s and not needed it. I guess maybe you work on industrial equipment that is exposed to harsh environments or something, although 30 years of tobacco mould build up isn't exactly nice. Again, ultrasonic cleaning is the best thing for that IME. If the pads are still dirty after cleaning with IPA (99% alcohol) then an eraser usually does the trick.

Then again if I had the money I might be tempted to shell out for flux.

NASA has always trained people to use a sponge and I'm willing to follow their lead.


Interesting, do you have a reference for that? I'd love to read it.

At college we always used a sponge but I'm a brass convert now. I find that I can clean excess solder off the tip a lot more quickly and easily with it. I think the reason is that the temperature drop, however limited, makes the solder stick to the tip rather than drop off when using a sponge. It's similar to how if you want to bridge two pads on matrix board and you heat one pad first the solder often will not make the join, but if you heat both at the same time it does it easily. Maybe using an 18W iron exacerbates the problem but I like the low power for other reasons.
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Re: Choosing a new soldering iron...

by mojo on Fri May 21, 2010 1:48 pm

charliex wrote:I love my metcal and I got a great deal off eBay , dozens of spare tips and a set of talons. Its the older model, but its still fantastic. It heats up so fast, nice auto off feature and i can switch between either two irons or iron and talons in a jiffy. Plus i really like how the tip temperature is set by the bit, no need to worry about it at all.


That reminds me of a hack I did at work because one guy kept leaving the iron on after use and the station didn't have an auto-off. Auto-off is definitely a valuable feature in a busy workshop with lots of distractions.

Anyway, I made a little ATtiny13 based beeper that pinged once every 5 minutes. I used parts from a USB charger to make the power supply and wedged the whole lot into a multisocket which ran two irons and hot-air station. That way if it pinged and no-one was using it I would manually turn it off. I thought about using a banned timer or something but the advantage of this hack is that it automatically turns on and off with the rest of the equipment. For safety reasons we always switch off at the mains.

PS. Why are switches on mains sockets not that popular outside the UK? Virtually all sockets here have switches, and it's very unusual to see an unswitched one.
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Re: Choosing a new soldering iron...

by charliex on Fri May 21, 2010 3:01 pm

That i wish i knew, the UK plug is so much better than the one in the USA, they're safer and better to rewire, they fit better and stay put. Fused plug is much more common in the UK too. I remember moving over here and trying to find a blank plug to rewire something, they're just not as common either.

The only common switched one i've seen in the US is the one that is switched via a remote lightswitch.

The auto off is indeed useful, epecially given how fast the metcal heats up. Even at home, UPS turns up with the latest gizmo and you forget all about it.
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Re: Choosing a new soldering iron...

by mojo on Fri May 21, 2010 7:19 pm

I believe that all plugs must now be fused in the UK. I took it for granted until I first went to Europe and then Japan. Japan in particular really surprised me. Probably the most high tech country in the world, a good 10 years ahead of the UK at any rate, and their sockets are terrible. Being energy concious you would think that switched sockets would be a given too. The whole 50/60Hz split is bizarre too.

Still, it's not that uncommon to see lights as spurs off a socket in this country, or a spur off a spur off a spur off next door's spur... When you buy a house it's almost impossible to know if someone has done something stupid like that so having fused plugs is pretty important.
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