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Trying to desolder some electrical components from a board

by res3210
Tags: board, components, desolder, electrical
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res3210
#1
Jun27-13, 06:58 PM
P: 44
I am not sure if I am allowed to post these kinds of questions here (cause I see mostly hypothetical ones, but then again I didn't look too far down the page...) but I just have a quick question for you guys. I am trying to desolder some electrical components from a board but I don't have anything to hold the board steady. Any recommendations on how to make a make shift one or a way to desolder without having to have a third hand? Thanks!
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phinds
#2
Jun27-13, 07:10 PM
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Quote Quote by res3210 View Post
I am not sure if I am allowed to post these kinds of questions here (cause I see mostly hypothetical ones, but then again I didn't look too far down the page...) but I just have a quick question for you guys. I am trying to desolder some electrical components from a board but I don't have anything to hold the board steady. Any recommendations on how to make a make shift one or a way to desolder without having to have a third hand? Thanks!
Get a "solder sucker" then, you don't need to be very steady, just press the button when the solder melts and it'll slurp it right off.
res3210
#3
Jun27-13, 07:13 PM
P: 44
I was afraid something like that would be unavoidable. Thanks again!

Averagesupernova
#4
Jun27-13, 07:31 PM
P: 2,499
Trying to desolder some electrical components from a board

Oh there are thousands of ways of doing stuff like that I am sure. For simple through-hole components like resistors or axial components just heat the connection, maybe add just a tiny bit more solder and using a right angle awl, scribe, pick, whatever you want to call it, lift it out of the hole one end at a time. To hold the board steady just weight it down with something. I have used a pair of needle-nosed pliers with a rubber band wrapped around the handle to grip smaller PC boards before. This will allow the board to sit on edge if you put something heavy across the pliers handles laying flat on the bench. Just be creative while being careful not to damage something.
res3210
#5
Jun27-13, 09:22 PM
P: 44
That is also a great idea! Thanks!!
Simon Bridge
#6
Jun27-13, 09:34 PM
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Blue-tack, putty, clothes pegs, a pair of pliers and a rubber band, two books... lots and lots of ways.
Bobbywhy
#7
Jun27-13, 09:35 PM
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Technicians that remove/replace components on Printed Circuit Boards (PCBs) use a small vise with rubber jaws to hold the board. (Much like Averagesupernova's suggestion above) Once the board is fixed in position, you can use a solder-sucker (Phinds mentioned it above) to "suck" the molten solder from the connection. It is a spring-loaded plunger in a tubular housing with a small opening at the tip of a protruding nozzle. The operator "cocks" the plunger, places it adjacent to the solder joint to be de-soldered, and applies heat with a soldering iron. When the solder melts she releases the plunger and as it snaps upwards it sucks in the molten solder. Of course, it solidifies inside the tube, and builds up after several sucks. This requires the technician to periodically open the sucker and remove the solder "blobs".

Another method that is common and effective is to use "solder wick". This "wick" is made from fine copper wires formed into a flat woven braid. It is readily available and comes in easy-to-use rolls. The technician puts a length of the braid onto the solder joint and holds the hot soldering iron tip against it. When the solder melts it is quickly "wicked" from the joint into the copper braid, leaving a clean empty hole. The component leg is then easily removed. Both methods are approved for use on military-standard electronic assemblies.
NascentOxygen
#8
Jun28-13, 12:44 AM
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Desoldering components is not a lot of fun. I find it's best done in a room where you are free to flick molten solder on the bench and floor. I heat the joint till the blob is molten, and no longer, then bump the board so the solder drops out and hopefully leaves me with the component lead free of most solder. This is practical only where the board is free, not bolted into the equipment. Then use solder wick to clean up any remaining solder.

There is no simple, easy way, especially when you are trying to salvage the component and not damage it in the process by over heating.

Good luck!
Averagesupernova
#9
Jun28-13, 01:01 PM
P: 2,499
What I have had the best luck with when replacing components is how I described, or for DIP ICs I will cut off each lead first. Then I use the iron to pull out each lead one at a time. Have a tray handy to tap the iron on and the lead will fall off the iron. I have gotten good enough at it so that I can pick several pins out of their holes before knocking them off of the iron. In fact, usually the IC lead pulls out without a pair of tweezers, it just sticks to the iron. After this I will set the board on edge and use a solder sucker on one side and the iron on the other side. The solder sucker I use is pneumatic. It runs on compressed air and using a venturi creates suction. So heating one side of the board with the iron and the other side with the solder sucker each hole is desoldered with one continuous sweep of both the iron and the solder sucker. Each side of a 14 pin DIP takes a couple of seconds to get the holes cleaned out. I have damaged far fewer boards using this method than any other way I have found so far. If for some reason I cannot use the solder sucker I will just use solder wick, but only after the leads have been removed from the hole. An empty hole is much much easier to remove solder from than one with a lead in it.
sophiecentaur
#10
Jun28-13, 05:00 PM
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Great advice to accept the loss of the component and to take out one lead at a time. Use a solder sucker and experiment with the soldering iron temperature to get the solder to melt quickly enough (but not too hot) do that you do not to roast the pads. Don't risk being too impatient to wait till you get a sucker - you could regret it.
I remember using a sort of branding iron device that heated all the pads at once and allowed the IC just to drop out. With plated through holes, this would not necessarily be best as you need to get the heat right through the pin to melt the solder in the hole.
Solder wick can be fine but I reckon you must be sure to use 'new stock'. I have had problems with an old length which needed to get very hot before it would work.
res3210
#11
Jun30-13, 09:25 PM
P: 44
Thank you all for your great advice!! Turns out my dad had a solder sucker that heats up! (I'm not sure if they sell ones that don't. If they do, those ones must be much more difficult to use) I managed to desolder a bunch of components effortlessly, that tool is great!
eq1
#12
Jul8-13, 02:40 PM
P: 33
Not the cheapest solution (~$200) but using a heat gun is a quick and easy way to do it. It also (usually) doesn't damage the component. It's pretty much the only solution to desolder a BGA.
http://www.youtube.com/watch?v=kYBxA9zJybE
turbo
#13
Jul8-13, 02:44 PM
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I prefer the solder-wick solution. It is cheap and controllable.
Mordred
#14
Jul8-13, 03:17 PM
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one quick trick no one mentioned if your desoldering a full board ie not worried about other connections use a heat gun or good blow dryer, handy trick to pull off 400+ pin Chips


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