Instructables

Desoldering tool

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Picture of Desoldering tool
It is a tool for desoldering (multi leg) electronic components with 3 or more pins.
Theory behind this project is fairly simple. Dissolved solder in heated container heats all contacts of electronic component placed together with PCB on this tool. All you have to do is remove component from PCB with pliers or with tweezers. So with this device you can easily desolder 25 pin LPT conector from 2 sided PCB.

Original article on my site here
 
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Step 1: Can selection

Picture of Can selection
First find some tin can, like this one from the picture.

Step 2: Can preparation

Picture of Can preparation
Then cut the bottom of the can. Later it will be used as container for melted solder. 1-2cm is sufficient height for container.

Step 3: Construction of heater

Picture of Construction of heater
For heater you need heater wire (NiCr). Usualy caled "cekas" od "nichrome". If you don't have any, take some from old heater in blow dryer or heating unit, and wind off 1m of wire. Measure resistance because you will need this information later in construction.
Before calculation you must have 2 more parameters . Power and voltage of heater.
Power of my heater is 100W, recommendation is not to go below that because it takes too long to melt down solder after power up.
Voltage must be adapted to power source that you will use. I have laboratory power source with regulation from 0-35V and I have chosen 30V for voltage of my heater.
Calculation:

U=30 V
P=100 W
rt=28,6 Ohm/m (resistance per one meter)
Rt= ? (resistance of heater)

Rt = U2 / P = 302 / 100 = 900 / 100 = 9 Ohma

Length of heater wire

L = Rt / rt = 9 / 28,6 = 0,3m

If you don't want to calculate parameters and you have a power supply with voltage regulation, just take piece of wire, connect it to power supply and rise voltage until wire (heater) gets to red glow. This method can be used for checking the calculated parameters.

On the picture is my heater. Coiled on 3mm drill borer and extended to desired length.
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i think it's totally awesome you made this. Question though, would just a regular stove burner element and a pan work?

tom3115711 year ago
I know lead is not a good thing to have in your system. Isn't that the most dangerous part? "fumes"
solder is only part lead, you can use lead for this but i wouldn't suggest it. just don't inhale the fumes and you'l be fine (id also recommend you have good ventilation or just go outside).
darman1211 months ago
Sweet idea! This is how PCB circuits are actually soldered. All of the components are placed on the board, then it skims across a bath of solder to quickly solder up all the components.

I like how this concept is made into a way to desolder.
You should use a hot iron, works pretty well.
tom3115711 year ago
I know lead is not a good thing to have in your system. Isn't that the most dangerous part? "fumes"
techno guy2 years ago
Won't the heat kill I.C.'s if you use this to remove them and then plan to reuse them?
a ic that would burn up from soldering temps probably isnt worth reusing.
pfred2 zack2472 years ago
Every semiconductor ever made can be destroyed by heat. The typical rating is 300C for 10 seconds. Notice that the time the heat is applied is a factor. The component would probably be much better off at 400C for 2 seconds too. That is how I work, hot and fast.

Generally I won't heat anything when I am soldering longer than 3 seconds. Once that time has elapsed I stop, wait for what I am doing to cool, and figure out what is going wrong.
My biggest fear with using salvaged parts comes from building them into a circuit and getting either random heat-induced malfunctioning, or death a few weeks after the circuit has been put into service. Most parts ARE degraded to some degree from non-controlled reheating which causes diminished performance or even premature failure.

A more reliable way of doing this is by preheating the board to 120C for 10 minutes or so prior to the solder dip to reduce the thermal shock. But that's not always practical or even possible.

The most reliable and simplest way of doing this is by using hot-air. It is almost instant heat, uses FAR less power, leaves no molten metal around to dump in your lap, and is as easy to handle as a soldering iron. Hot-air will also allow you to do repair work too by varying the temperature, it will let you do reflow soldering when using a solder paste on the pads (just put the part on the paste and the hot-air causes it to automatically solder the part with perfect joints). This also makes it a great heat-shrink tool because there is no flame to degrade the plastic tubing, so this one device can by used for so many things - and they are sold for around $75 online. (Check ebay)

They come in many configurations at a variety of prices. The full-featured one I bought has variable heat and variable airflow - but it also has a variable temp soldering-iron, and even a 1A variable-voltage DC power supply too. These are typically called a "rework station", but for the purpose of recovering parts you would not need such a "fancy" item. Incidentally, the price of it was only around $150 and included several types of soldering tips, several shapes of air nozzles, a solder reel and an soldering-iron holder. Also there is an airflow indicator (vertical tube with floating ball), and six digital LED readout displays for the various functions so you can monitor exactly what is going on.

Originally I bought one of the basic units to transfer SMD parts from my older-design boards into the new version boards, but the tool has been used for at least a dozen other things - I cannot believe I worked without one for so long.
Thank you, did not realize they were so capable and versatile...
Thank you for letting me know about your experiences with your hot air station. I tend to avoid several things you mention, such as, ebay, reflow, and SMT. None of that is congruent with me. As for the rest, I'm managing with equipment I already possess.
Well, I'm afraid that I wasn't directing my comment at you, but rather attaching it to one of the more recent segments of the thread. As you can see, I was careful to add a lot of detail so that other readers could benefit from what I wrote.

Mentioning eBay was not a suggestion to *purchase* from eBay , but rather as a catalogue to see what sorts of items are available, what they're formally called and what brand names to look for. (hence the "check eBay" rather than "buy it off eBay") I rarely buy from eBay, I find that it makes a great catalogue for things you may not know exist, or simply not know the names of. Many people I know use it for that purpose, due in part to the great search engine capabilities.

So yeah, I'm not suggesting that *you* buy anything. I was explaining what worked for ME, and what techniques I found helpful. I'm sure someone out there reading it would have found something to be "congruent" to them, in one way or another.
I'm sorry but you did reply to me. Next time check the top of the page for a comments link if you do not wish to address me.
Oh, don't worry about that...I've certainly learned the lesson of not trying to attach my comment to other relevant comments with similar dates.
Please accept my deepest apologies for such transgressions, I don't know where my lapse of judgment came from but it won't be repeated. GFS
damirvk (author)  techno guy2 years ago
If you quickly remove component heat won't kill her
80% of components desoldered this way are reusable.
pfred2 damirvk2 years ago
My success rate is somewhat higher over 90% The few I do lose I'm probably better off not using anyways.
qualia pfred22 years ago
*flourishing bow*
pfred2 qualia2 years ago
I saw a video recently of component scavenging going on in China and all the guy had was a dished piece of sheet metal over a heat source, with molten lead pooled on it. He was banging away! If I'd seen that before I got my solder pot well, maybe things would be different here today?
You're going to kill a lot more components playing with one lead at a time than if you can pull it out quickly all at once.
ddrdan2 years ago
Just pick up a cheap $15 deep fat fryer at Walmart. Mod the top of the plastic case and file off the 400 degree thermostats limit stop. Takes a while to heat up, but it's "Safe" and effective. You can use pieces of lead to fill the pot and minimize the solder quantity needed.

PS: And you can use the basket strainer that comes with it in a stove top pot if you "want fries with that". LOL
sconner12 years ago
Industrial soldering methods at home. cool. I mean Hot!
I agree this is a severe burn and fire hazard.
One might set this apparatus into a shallow cake pan or deep cookie sheet to catch spills. Attach the legs to the pan with epoxy to avoid tipping it over.
alexanderm3 years ago
Great idea! Thanks for the Ible!

While i'm not keen on the use of this for desoldering SMD components, as it isn't usable on just a single component (it would mess up the solder on other components), could easily overheat the components, and i don't care for the integral instability, it offers inspiration! i think i might use the idea to create a solder pot. For the uninitiated, a solder pot is useful for tinning, amongst other things.

Some suggestions for upgrading: Use a ceramic container, placing the coil with ceramic standoffs in the bottom, and the can on top of the coil. This would waste less heat/energy, and allow for tabletop placement. The supply wires could be run through the side of the ceramic container. The ceramic container could be cut down to size for your use.

For those asking about the volume used, the more solder used, the more constant the heat retention. If the container is insulated, the volume of solder used, could be significantly reduced. This would also reduce spill danger.
Professional pots, one of which I happen to own, are made out of metal. I think you might run into problems with a ceramic container if the rates of expansion varied while heating up. The last thing you want to have happen is to have a large amount of molten solder running all over the place if the vessel you held it in broke!
qualia pfred22 years ago
I believe if he has enough sense to use a ceramic insulator around the steel can he would also have enough sense to allow some space as an expansion joint. i dont think there would be an infinitesimal enough range of sizes of preformed ceramic containers or dishes to actually acheive a press fit for a standard tin can anyway so i believe the average joe would opt to buy/scrounge the next size up.

Are you absolutely sure your solder bath is not sheet metal around some sort of solid ceramic or ceramic fibre insulation with the heating element/s (nichrome, resonant coil) only heating a specific area? If it fails to have a refractory material i think your professional pot may not be so professional, in the economy of energy/resources sense.

Not that i disrespect you and your fancy equipment or anything. It was wise of you to warn others of the dangers of molten metal if anyone else who misread that comment as you did would actually construct a solder bath based on that principle, with no steel liner/crucible and a heating element on the wrong side of the refractory, possibly with the intention of insulating it from the molten solder.. good intentions....
pfred2 qualia2 years ago
I have an esico solder pot. I am absolutely sure it is made out of solid cast iron. The name plate on it is some kind of sheet metal. I should have called it a commercial industrial solder pot I suppose.

What gap is between the solder and the vessel that holds it?

When you have a mass of molten metal, even lead well, I guess you just have to be there I suppose to fully appreciate the kind of hazard it presents. When dealing with non metallic crucibles you're never supposed to heat them up with solidified material in them. It is a common safety procedure I was merely pointing out.
Eisco37.jpg
qualia pfred22 years ago
yeah apologies for that rude comment i left last night, i was pissed off at my probation officer and i was tired and i took it out on the haves. still i'm fairly sure that post wasnt mentioning a non metallic crucible, just a refractory container to maintain heat in the metallic crucible (steel can).
pfred2 qualia2 years ago
I'll accept, just to be gracious, but no harm, so no foul. My solder pot doesn't have any insulation, it just has 800 Watts of heating goodness. It does take it some time to come up to temperature though. I never timed it but I usually think in terms of say 40 minutes? It probably heats up faster than that, but when I plan on using it I plug it in then go do something else for a while. You know what they say, a watched pot never boils!

As far as maintaining heat goes once it goes molten after I shut it down I just leave it where it is until the next day. It takes a lot longer to cool down than it does to heat up.
jpoopdog2 years ago
Has anyone gotten this to work with 24v? or 75v?
I have discovered that old Christmas light transformers are an excellent source of power, many supply between 75-150VA, which can be considered a bit higher than the respective wattage. im currently experimenting though.

Making the bottom airtight, and using less solder in the pots, would make melting time shorter. and the whole thing more energy efficient. also , im not certain, but i do beleive sandwiching the nichrome between two mica sheets is a suitable way insulate electrically, and transfer maximum heat.

Also, ive heard that pushing low frequency audio sounds through the molten solder helps it melt, as well as become more runny.
Anyone heard of this?
SharpyWarpy3 years ago
Hi damirvk and thank you very much for sharing your solder pot build.
I built this using your directions with a couple of differences. I don't have any of the light duty heating element, only some out of an old 220v clothes dryer. I couldn't get the math right -- the old grey head ain't what it used to be -- so I experimented with different voltages starting with 12v. I used an old microwave oven transformer for power. I cut off the secondary winding of said transformer and wound it for 12v, which as those experienced with these transformers know requires 12 windings, one per output volt. I kept adding windings until I had 16v, which got the element nice and red. I used fairly closely wound element inside the ceramic insulators. I didn't bother with converting to DC. I have lots of lead in my junk pile (I love my junk pile) and used some of that and half a spool of old acid core solder. The unit takes the same amount of time as yours to heat up the solder to a liquid state. The liquid is beautiful and fun to watch and play around with. I use an old spoon to skim off dross. I keep the pot well away from the edge of the table so spills are not a big problem.

damirvk (author)  SharpyWarpy3 years ago
Hi
I am very glad that you like my build.
Also you made clever modifications that will help future builders.

BR
Damir
Here are some pics of the solder pot I built using your instructions. Thanks again. I have wanted one of these for a couple of years but never knew quite where to start.
full_rig.jpgtransformer.jpgelement-to-transformer_connection.jpgelement-glowing-red-hot.jpg
wow, that is either very thick wire, or a tiny little pot.

damirvk (author)  SharpyWarpy3 years ago
Nice work.
Quite bigger pot than my.
tnx for pics
Rainh2o2 years ago
Why use this to remove a component? I remove and replace 3-100 pin components regularly with a scope, a fine pointed dental pick and a nice solder iron. The only thing I ever use a solder pot for is tinning large amounts of wire leads or larger legged components. I think you would risk created solder shorts with this. just my opinion. Nice project for making a solder pot or any other pot for heating things though!
pfred2 Rainh2o2 years ago
I use a solder pot to strip parts off scrap circuit boards. It isn't a technique designed for rework. A lot of folks seem to have difficulties realizing that scrapping and reworking are two different things. When I am scrapping a board I could care less about the board itself. It is garbage!
jgosselin2 years ago
would love to know where to get these insulators. they are as far as i can tell non-existent around where i live.
jpoopdog2 years ago
one last thing, your calculation is way off. in the way it is formatted
it should be like this ↓

Rt = U² / P
= 30² / 100
= 900 / 100
= 9 Ohms

the way you have it, it looks like

Rt= U (²/P=30) 2/100 = 900/100 = 9 ohms
saying that it Rt is U to the power of 2 / P which for some reason = 30.
Anyway, it confused me, im sur eit might do so to others.
jpoopdog2 years ago
whoops, sorry to double post, but i thought ide just say that i am going to make an alteration of this design. which uses a small tap (also heated) in order to drain the molten contents out, preferably for smelting/casting lead, and in my case, zinc.

Ill publish an instructable on it, but ill be sure to give full credits for everything ill be copying from here, or rather basing my design from anyway.
jpoopdog2 years ago
The stand is meerly an improvisation, im sure any Regular person who doesnt know what their doing, unlike our friend damirvk here, would understand that they dont know how to do this safely, and would go ahead and build this either just sitting on the ground, or on a peice of sheet metal, or as logic would forgo, a sliced section of the can, and the can lid (or another bottom of the can), which could be linked with the bolt.

This guy obviousy knows the limitations of his creation, and the dangers.
besides, your heating element, if from a hair dryer , wouldnt last that long, since it is very hot, and is exposed to open air, actually litterally sucking in air and blowing it out if you had thermal imaging technologies you could see it better.
It would be best if the whole thing were incased in something, which would not only increase its heat, making it more efficient, but it would also last very long, as it would not oxidize, as much.

Great work though! im gonna build one jsut like this, hopefully able to reach in excess of 500 celcius! as i need to smelt zinc.
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