How to remove IC safely from PCB

[Phiredog]

I have an old modem with an LM386 chip on the board. How do I safely remove it? The leads are too short to just cut and I wasn't sure about how well it handles heat from a soldering iron.

Thanks for all of the help. This forum is great!

Bill

[gtrmac]

Well you have to use heat but a solder removing tool would help. Better experiment on some expendable parts first if you really want the IC. They only cost about 50 cents though.

[Peter Snowberg]

The only sure-fire way is to use a desoldering iron with a vacuum pump. You can also use a regular iron and a solder sucker but quite often you will get poor results, shredded boards, and heat damaged components.

I had a 386 amp for several months that was made by just cutting two traces on a 33.6 modem with jacks added for the guitar and speaker. It worked great until I accidentally touched the battey to it in reverse one day. Put a diode in-line to prevent repeating my error. I just cut off the little 1 inch speaker and connected the wires to a headphone jack and then from there to a 10 inch unit. Also try putting a 500 ohm pot in-line for a volume control.

You might be able to just pull out the rest of the stuff around the 386 portion and use the board as-is, or even use tin snips to trim out the 386 and support parts.

Recycle away! (but remember that those chips are really cheap and readily available)
-Peter

[Paul Perry (Frostwave)]

It's pretty hard to get chips out! especially with plated thru holes. I'd agree, use snips to cut away the pcb as much as you can. Honestly, I'm a total scrounger, but getting "ordinary" chips isn't any fun! perhaps for practice! (I've had to do it with rare out of prod. chips)

[smoguzbenjamin]

Speak for yourselves, people  :wink:  it's a pain in the rear-end getting an LM386 where I live, I'll have to mail-order them, which costs me a fortune in postal handling costs... I can only get the 6V version, not the 5-12V  :cry:

So if I found an LM386 chip ANYWHERE i'd rip it off instantly :mrgreen:

[afranks]

Radio Shack sells a decent vacuum bulb desoldering iron that works well for removing ICs.  It has a hollow tip and a rubber bulb you release to suck up the solder.  I think mine was $15.  Once you get all the solder removed, you may still need to touch a soldering iron to the pins as you pry the IC up (lightly) with a jewelers screwdriver or xacto knife.  If you don't want to spring for a cheap desoldering iron, you can try using desolder wick, but you might overheat the IC.  I prefer the desoldering iron myself.

-alan

[drew]

I have scavenged loads of rare parts from broken synths.... both to repair other broken synths or create my own stuff... and I can offer that the best way I've found by now is to use a butane mini-torch on the solder side of the board, aimed so that you can pull up all or most of the pins in one (CAREFUL) yank once the solder is molten!

Otherwise, it's VERY easy to overheat the chip, as working the chip out of the board using a soldering iron will require that you heat EACH PIN several times! Even using a desoldering tool will ensure that you have to heat each pin two or three times, because little bits of solder residue will stick a pin to the side of a hole, or wick inside thru-plated holes. Using a torch eliminates those problems.

The board will most likely make an awful smell, and turn black, but you can get stuff out of it fairly easily this way. What have I scavenged this way? CEM chips out the butt, uA726, voice chips, japanese transistors (hard to find here, those!), matched transistor pairs, and multi-pin headers. All of them worked, except the first couple that I tried to do. (Like soldering, it's not as easy as it looks...)

This is the "trash the board, get the parts" method. If you want the "trash the parts, get the board" method, desoldering is of course preferable... and if you're lazy, I can tell you about the "trash the board, trash the parts" method


drew
toothpastefordinner.com

[Ansil]

i have only burned one chip so far, since i started taking parts off of boards..   the way i do it is fairly easy.

take a jewelers screwdriver..(flathead)  and slide it under the chip.  work it just a little.  concentrate on one side of the chip now with the soldering iron.. i use a 40watt and just tap each leg just a split second to get the solder loose.

now the screwdriver will slip in there easier.

wait let chip cool

do other side.

you are basically turning their machine soldering job into a crappy dry solder joint.  the dry solder joint.  (flat ugly dull gray color, bad for connections)  will permit the chip to wiggle.  then you go back and hit all four pins on ones side at the same time..  

(you can do it with a regualr tip but i used a grinder to make one side of mine flat to aid in this makes it much easier.)  

as soon as the solder starts to melt using your other hand on the screwdriver and just pry it up.


also things to try that help, are to put hemostats on the pins once you can get them under the chip.  they will help disapate the heat.

and once you have half the chip out you no longer need the screwdriver.
just attach the hemos to the other sides pins and apply heat to the bottom and let her fly.


another option, is to use ultra small surgical hemo's and just pull the compnents from the board  you have to get a good bite on them though.

[Ge_Whiz]

Use a hot-air paint stripper (electrical). Mount the PCB tightly in a vice, heat from the solder side until the solder melts on all pins simultaneously, and pull the component out - NOT USING YOUR FINGERS! Use a screwdriver (gently), pliers or forceps. The board will cook but will screen the components from damage. This is absolutely, guaranteed, the best way to strip a PCB of components. I have done it many times and all the components have subsequently worked fine. The best tip I ever got.

[Ansil]

Use a hot-air paint stripper (electrical). Mount the PCB tightly in a vice, heat from the solder side until the solder melts on all pins simultaneously, and pull the component out - NOT USING YOUR FINGERS! Use a screwdriver (gently), pliers or forceps. The board will cook but will screen the components from damage. This is absolutely, guaranteed, the best way to strip a PCB of components. I have done it many times and all the components have subsequently worked fine. The best tip I ever got.

i was wondering about that, i never had the means to try it and wondered if it would work,,    BRAVO!!

[Mark Hammer]

If it's coming off a modem, there is a very good chance you are dealing with a double-sided board.   These are much harder to desolder.  Having salvaged plenty of chips from such boards, however, I would recommend the following:

a) HEATSINK the damn chip so it makes it through the "escape" alive.  If you lack any sort of clip-on heatsink the simplest quick sub is to take a piece of tissue, toilet paper or paper towel, fold it up into a little tablet-size piece and soak it in cold water.  Lay it up against the chip, flip the board over to desolder and not only will you have something to soak up the heat, you'll also have an audible indicator if you are applying too much heat (the hiss of steam being formed).

b) I find that the paltry amount of solder on professional solder joints, especially on digital boards, does not make for very good solder flow, and consequently very poor solder suckage (is that a word?).  If its a double-sided board this is an even bigger problem.  To remedy this, melt a small blob of solder onto each of the chip's pins, making sure to wait a little before putting solder onto the next pin, just to give the thing a chance not to heat up too much.  A good strategy is to apply heat to opposite pins, e.g., pin 1 and 5, or 4 and 8.  Once you have a bit more solder on there, THEN heat it up and suck away.  I think yu'll find you get much more off by adding a little up front.  Think of it like a running start.

c) Even though things can look clear, there ALWAYS seem to be little solder webs here and there that can make your life miserable.  Even though I've successfully unsoldered plenty of components, every now and then you get something that is a little more securely attached to the board than it looked and the chip comes off but one or tweo pins are sadly left behind.  To avoid this, once you THINK you've taken all the solder out of there, grasp the pins with some needle-nose pliers and give each pin a little wiggle to break the last few tiny solder webs and free it.  This is also very helpful when dealing with double-sided boards where you probably can't even see if the chip is still secured by solder on the component side.  If it wiggles freely, you're in the clear.