Desoldering Tool

Intro: 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

STEP 1: Can Selection

First find some tin can, like this one from the picture.

STEP 2: 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

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.

STEP 4: Heater Isolation

Finished heater must be somehow isolated from metal housing. I have used ceramic insulators removed from old baking oven heater. If you don't have insulators buy them in repair shop for kitchen appliances.

STEP 5: Can Attachment

Can from beginning of text somehow must be attached to housing, for that purpose main is drilled through middle and PCB spacer is attached to can with screw. Plain screw with few nuts can be used.

STEP 6: Heater Installation

Heater installed in can slot.

STEP 7: Heater Mounting

Heater is pressed to can with grill from PC fan.

STEP 8: Legs Mounting

Screws with nuts are used for "legs" of device, and ceramic connection block is mounted to hold outlets of heater.

STEP 9: First Run

Desoldering tool connected to power supply, and peaces of solder are melting in can.

STEP 10: Tool in Use

On next pictures desoldering proces is shown step by step.

STEP 11:

Short video samples of device in use:
Video 1 640x480, 18.7MB
Video 2 320x240, 18MB
Video 3 320x240, 19MB

Comments

[Norway1973]

Thanks for a good instructable! :-)

I made this,just took a shortcut and placed the can on top of a small propane burner,skipping your heater part. The can melts the tin,but when I tried it yesterday,I did not manage to get any componentes free even after an extended "dip" in the melted tin. Any clues why?

I placed the part of the bord where the component was on top of and in contact with the molten tin and tried to pull the component off with a plier. No luck even after leaving it there for 10sek ( it was a switch I just tested with,so I didn't care if I killed it..... )

[Power Tools Pro]

Brilliant idea.

[avocadostains]

i think it's totally awesome you made this. Question though, would just a regular stove burner element and a pan work?

[tom311571]

I know lead is not a good thing to have in your system. Isn't that the most dangerous part? "fumes"

[my wookie]

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).

[darman12]

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.

[faacuunndoo]

You should use a hot iron, works pretty well.

[tom311571]

I know lead is not a good thing to have in your system. Isn't that the most dangerous part? "fumes"

[techno guy]

Won't the heat kill I.C.'s if you use this to remove them and then plan to reuse them?

[zack247]

a ic that would burn up from soldering temps probably isnt worth reusing.

[pfred2]

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.

[LaserDave]

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.

[VidDroog]

Thank you, did not realize they were so capable and versatile...

[pfred2]

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.

[LaserDave]

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.

[pfred2]

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.

[LaserDave]

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]

If you quickly remove component heat won't kill her
80% of components desoldered this way are reusable.

[pfred2]

My success rate is somewhat higher over 90% The few I do lose I'm probably better off not using anyways.

[qualia]

*flourishing bow*